[457] | 1 | /**
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| 2 | * @file
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| 3 | * Transmission Control Protocol, incoming traffic
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| 4 | *
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| 5 | * The input processing functions of the TCP layer.
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| 6 | *
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| 7 | * These functions are generally called in the order (ip_input() ->)
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| 8 | * tcp_input() -> * tcp_process() -> tcp_receive() (-> application).
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| 9 | *
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| 10 | */
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| 11 |
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| 12 | /*
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| 13 | * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
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| 14 | * All rights reserved.
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| 15 | *
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| 16 | * Redistribution and use in source and binary forms, with or without modification,
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| 17 | * are permitted provided that the following conditions are met:
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| 18 | *
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| 19 | * 1. Redistributions of source code must retain the above copyright notice,
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| 20 | * this list of conditions and the following disclaimer.
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| 21 | * 2. Redistributions in binary form must reproduce the above copyright notice,
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| 22 | * this list of conditions and the following disclaimer in the documentation
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| 23 | * and/or other materials provided with the distribution.
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| 24 | * 3. The name of the author may not be used to endorse or promote products
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| 25 | * derived from this software without specific prior written permission.
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| 26 | *
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| 27 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
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| 28 | * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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| 29 | * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
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| 30 | * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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| 31 | * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
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| 32 | * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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| 33 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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| 34 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
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| 35 | * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
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| 36 | * OF SUCH DAMAGE.
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| 37 | *
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| 38 | * This file is part of the lwIP TCP/IP stack.
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| 39 | *
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| 40 | * Author: Adam Dunkels <adam@sics.se>
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| 41 | *
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| 42 | */
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| 43 |
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| 44 | #include "lwip/opt.h"
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| 45 |
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| 46 | #if LWIP_TCP /* don't build if not configured for use in lwipopts.h */
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| 47 |
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| 48 | #include "lwip/priv/tcp_priv.h"
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| 49 | #include "lwip/def.h"
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| 50 | #include "lwip/ip_addr.h"
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| 51 | #include "lwip/netif.h"
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| 52 | #include "lwip/mem.h"
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| 53 | #include "lwip/memp.h"
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| 54 | #include "lwip/inet_chksum.h"
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| 55 | #include "lwip/stats.h"
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| 56 | #include "lwip/ip6.h"
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| 57 | #include "lwip/ip6_addr.h"
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| 58 | #if LWIP_ND6_TCP_REACHABILITY_HINTS
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| 59 | #include "lwip/nd6.h"
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| 60 | #endif /* LWIP_ND6_TCP_REACHABILITY_HINTS */
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| 61 |
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| 62 | #include <string.h>
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| 63 |
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| 64 | #ifdef LWIP_HOOK_FILENAME
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| 65 | #include LWIP_HOOK_FILENAME
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| 66 | #endif
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| 67 |
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| 68 | /** Initial CWND calculation as defined RFC 2581 */
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| 69 | #define LWIP_TCP_CALC_INITIAL_CWND(mss) ((tcpwnd_size_t)LWIP_MIN((4U * (mss)), LWIP_MAX((2U * (mss)), 4380U)))
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| 70 |
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| 71 | /* These variables are global to all functions involved in the input
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| 72 | processing of TCP segments. They are set by the tcp_input()
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| 73 | function. */
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| 74 | static struct tcp_seg inseg;
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| 75 | static struct tcp_hdr *tcphdr;
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| 76 | static u16_t tcphdr_optlen;
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| 77 | static u16_t tcphdr_opt1len;
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| 78 | static u8_t *tcphdr_opt2;
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| 79 | static u16_t tcp_optidx;
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| 80 | static u32_t seqno, ackno;
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| 81 | static tcpwnd_size_t recv_acked;
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| 82 | static u16_t tcplen;
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| 83 | static u8_t flags;
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| 84 |
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| 85 | static u8_t recv_flags;
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| 86 | static struct pbuf *recv_data;
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| 87 |
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| 88 | struct tcp_pcb *tcp_input_pcb;
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| 89 |
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| 90 | /* Forward declarations. */
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| 91 | static err_t tcp_process(struct tcp_pcb *pcb);
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| 92 | static void tcp_receive(struct tcp_pcb *pcb);
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| 93 | static void tcp_parseopt(struct tcp_pcb *pcb);
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| 94 |
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| 95 | static void tcp_listen_input(struct tcp_pcb_listen *pcb);
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| 96 | static void tcp_timewait_input(struct tcp_pcb *pcb);
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| 97 |
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| 98 | static int tcp_input_delayed_close(struct tcp_pcb *pcb);
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| 99 |
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| 100 | #if LWIP_TCP_SACK_OUT
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| 101 | static void tcp_add_sack(struct tcp_pcb *pcb, u32_t left, u32_t right);
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| 102 | static void tcp_remove_sacks_lt(struct tcp_pcb *pcb, u32_t seq);
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| 103 | #if defined(TCP_OOSEQ_BYTES_LIMIT) || defined(TCP_OOSEQ_PBUFS_LIMIT)
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| 104 | static void tcp_remove_sacks_gt(struct tcp_pcb *pcb, u32_t seq);
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| 105 | #endif /* TCP_OOSEQ_BYTES_LIMIT || TCP_OOSEQ_PBUFS_LIMIT */
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| 106 | #endif /* LWIP_TCP_SACK_OUT */
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| 107 |
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| 108 | /**
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| 109 | * The initial input processing of TCP. It verifies the TCP header, demultiplexes
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| 110 | * the segment between the PCBs and passes it on to tcp_process(), which implements
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| 111 | * the TCP finite state machine. This function is called by the IP layer (in
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| 112 | * ip_input()).
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| 113 | *
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| 114 | * @param p received TCP segment to process (p->payload pointing to the TCP header)
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| 115 | * @param inp network interface on which this segment was received
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| 116 | */
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| 117 | void
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| 118 | tcp_input(struct pbuf *p, struct netif *inp)
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| 119 | {
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| 120 | struct tcp_pcb *pcb, *prev;
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| 121 | struct tcp_pcb_listen *lpcb;
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| 122 | #if SO_REUSE
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| 123 | struct tcp_pcb *lpcb_prev = NULL;
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| 124 | struct tcp_pcb_listen *lpcb_any = NULL;
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| 125 | #endif /* SO_REUSE */
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| 126 | u8_t hdrlen_bytes;
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| 127 | err_t err;
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| 128 |
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| 129 | LWIP_UNUSED_ARG(inp);
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| 130 | LWIP_ASSERT_CORE_LOCKED();
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| 131 | LWIP_ASSERT("tcp_input: invalid pbuf", p != NULL);
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| 132 |
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| 133 | PERF_START;
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| 134 |
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| 135 | TCP_STATS_INC(tcp.recv);
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| 136 | MIB2_STATS_INC(mib2.tcpinsegs);
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| 137 |
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| 138 | tcphdr = (struct tcp_hdr *)p->payload;
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| 139 |
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| 140 | #if TCP_INPUT_DEBUG
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| 141 | tcp_debug_print(tcphdr);
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| 142 | #endif
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| 143 |
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| 144 | /* Check that TCP header fits in payload */
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| 145 | if (p->len < TCP_HLEN) {
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| 146 | /* drop short packets */
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| 147 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: short packet (%"U16_F" bytes) discarded\n", p->tot_len));
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| 148 | TCP_STATS_INC(tcp.lenerr);
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| 149 | goto dropped;
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| 150 | }
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| 151 |
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| 152 | /* Don't even process incoming broadcasts/multicasts. */
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| 153 | if (ip_addr_isbroadcast(ip_current_dest_addr(), ip_current_netif()) ||
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| 154 | ip_addr_ismulticast(ip_current_dest_addr())) {
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| 155 | TCP_STATS_INC(tcp.proterr);
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| 156 | goto dropped;
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| 157 | }
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| 158 |
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| 159 | #if CHECKSUM_CHECK_TCP
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| 160 | IF__NETIF_CHECKSUM_ENABLED(inp, NETIF_CHECKSUM_CHECK_TCP) {
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| 161 | /* Verify TCP checksum. */
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| 162 | u16_t chksum = ip_chksum_pseudo(p, IP_PROTO_TCP, p->tot_len,
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| 163 | ip_current_src_addr(), ip_current_dest_addr());
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| 164 | if (chksum != 0) {
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| 165 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packet discarded due to failing checksum 0x%04"X16_F"\n",
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| 166 | chksum));
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| 167 | tcp_debug_print(tcphdr);
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| 168 | TCP_STATS_INC(tcp.chkerr);
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| 169 | goto dropped;
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| 170 | }
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| 171 | }
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| 172 | #endif /* CHECKSUM_CHECK_TCP */
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| 173 |
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| 174 | /* sanity-check header length */
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| 175 | hdrlen_bytes = TCPH_HDRLEN_BYTES(tcphdr);
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| 176 | if ((hdrlen_bytes < TCP_HLEN) || (hdrlen_bytes > p->tot_len)) {
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| 177 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: invalid header length (%"U16_F")\n", (u16_t)hdrlen_bytes));
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| 178 | TCP_STATS_INC(tcp.lenerr);
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| 179 | goto dropped;
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| 180 | }
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| 181 |
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| 182 | /* Move the payload pointer in the pbuf so that it points to the
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| 183 | TCP data instead of the TCP header. */
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| 184 | tcphdr_optlen = (u16_t)(hdrlen_bytes - TCP_HLEN);
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| 185 | tcphdr_opt2 = NULL;
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| 186 | if (p->len >= hdrlen_bytes) {
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| 187 | /* all options are in the first pbuf */
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| 188 | tcphdr_opt1len = tcphdr_optlen;
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| 189 | pbuf_remove_header(p, hdrlen_bytes); /* cannot fail */
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| 190 | } else {
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| 191 | u16_t opt2len;
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| 192 | /* TCP header fits into first pbuf, options don't - data is in the next pbuf */
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| 193 | /* there must be a next pbuf, due to hdrlen_bytes sanity check above */
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| 194 | LWIP_ASSERT("p->next != NULL", p->next != NULL);
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| 195 |
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| 196 | /* advance over the TCP header (cannot fail) */
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| 197 | pbuf_remove_header(p, TCP_HLEN);
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| 198 |
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| 199 | /* determine how long the first and second parts of the options are */
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| 200 | tcphdr_opt1len = p->len;
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| 201 | opt2len = (u16_t)(tcphdr_optlen - tcphdr_opt1len);
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| 202 |
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| 203 | /* options continue in the next pbuf: set p to zero length and hide the
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| 204 | options in the next pbuf (adjusting p->tot_len) */
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| 205 | pbuf_remove_header(p, tcphdr_opt1len);
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| 206 |
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| 207 | /* check that the options fit in the second pbuf */
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| 208 | if (opt2len > p->next->len) {
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| 209 | /* drop short packets */
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| 210 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: options overflow second pbuf (%"U16_F" bytes)\n", p->next->len));
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| 211 | TCP_STATS_INC(tcp.lenerr);
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| 212 | goto dropped;
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| 213 | }
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| 214 |
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| 215 | /* remember the pointer to the second part of the options */
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| 216 | tcphdr_opt2 = (u8_t *)p->next->payload;
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| 217 |
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| 218 | /* advance p->next to point after the options, and manually
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| 219 | adjust p->tot_len to keep it consistent with the changed p->next */
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| 220 | pbuf_remove_header(p->next, opt2len);
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| 221 | p->tot_len = (u16_t)(p->tot_len - opt2len);
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| 222 |
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| 223 | LWIP_ASSERT("p->len == 0", p->len == 0);
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| 224 | LWIP_ASSERT("p->tot_len == p->next->tot_len", p->tot_len == p->next->tot_len);
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| 225 | }
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| 226 |
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| 227 | /* Convert fields in TCP header to host byte order. */
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| 228 | tcphdr->src = lwip_ntohs(tcphdr->src);
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| 229 | tcphdr->dest = lwip_ntohs(tcphdr->dest);
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| 230 | seqno = tcphdr->seqno = lwip_ntohl(tcphdr->seqno);
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| 231 | ackno = tcphdr->ackno = lwip_ntohl(tcphdr->ackno);
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| 232 | tcphdr->wnd = lwip_ntohs(tcphdr->wnd);
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| 233 |
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| 234 | flags = TCPH_FLAGS(tcphdr);
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| 235 | tcplen = p->tot_len;
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| 236 | if (flags & (TCP_FIN | TCP_SYN)) {
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| 237 | tcplen++;
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| 238 | if (tcplen < p->tot_len) {
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| 239 | /* u16_t overflow, cannot handle this */
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| 240 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: length u16_t overflow, cannot handle this\n"));
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| 241 | TCP_STATS_INC(tcp.lenerr);
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| 242 | goto dropped;
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| 243 | }
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| 244 | }
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| 245 |
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| 246 | /* Demultiplex an incoming segment. First, we check if it is destined
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| 247 | for an active connection. */
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| 248 | prev = NULL;
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| 249 |
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| 250 | for (pcb = tcp_active_pcbs; pcb != NULL; pcb = pcb->next) {
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| 251 | LWIP_ASSERT("tcp_input: active pcb->state != CLOSED", pcb->state != CLOSED);
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| 252 | LWIP_ASSERT("tcp_input: active pcb->state != TIME-WAIT", pcb->state != TIME_WAIT);
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| 253 | LWIP_ASSERT("tcp_input: active pcb->state != LISTEN", pcb->state != LISTEN);
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| 254 |
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| 255 | /* check if PCB is bound to specific netif */
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| 256 | if ((pcb->netif_idx != NETIF_NO_INDEX) &&
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| 257 | (pcb->netif_idx != netif_get_index(ip_data.current_input_netif))) {
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| 258 | prev = pcb;
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| 259 | continue;
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| 260 | }
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| 261 |
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| 262 | if (pcb->remote_port == tcphdr->src &&
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| 263 | pcb->local_port == tcphdr->dest &&
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| 264 | ip_addr_cmp(&pcb->remote_ip, ip_current_src_addr()) &&
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| 265 | ip_addr_cmp(&pcb->local_ip, ip_current_dest_addr())) {
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| 266 | /* Move this PCB to the front of the list so that subsequent
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| 267 | lookups will be faster (we exploit locality in TCP segment
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| 268 | arrivals). */
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| 269 | LWIP_ASSERT("tcp_input: pcb->next != pcb (before cache)", pcb->next != pcb);
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| 270 | if (prev != NULL) {
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| 271 | prev->next = pcb->next;
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| 272 | pcb->next = tcp_active_pcbs;
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| 273 | tcp_active_pcbs = pcb;
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| 274 | } else {
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| 275 | TCP_STATS_INC(tcp.cachehit);
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| 276 | }
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| 277 | LWIP_ASSERT("tcp_input: pcb->next != pcb (after cache)", pcb->next != pcb);
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| 278 | break;
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| 279 | }
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| 280 | prev = pcb;
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| 281 | }
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| 282 |
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| 283 | if (pcb == NULL) {
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| 284 | /* If it did not go to an active connection, we check the connections
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| 285 | in the TIME-WAIT state. */
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| 286 | for (pcb = tcp_tw_pcbs; pcb != NULL; pcb = pcb->next) {
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| 287 | LWIP_ASSERT("tcp_input: TIME-WAIT pcb->state == TIME-WAIT", pcb->state == TIME_WAIT);
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| 288 |
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| 289 | /* check if PCB is bound to specific netif */
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| 290 | if ((pcb->netif_idx != NETIF_NO_INDEX) &&
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| 291 | (pcb->netif_idx != netif_get_index(ip_data.current_input_netif))) {
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| 292 | continue;
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| 293 | }
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| 294 |
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| 295 | if (pcb->remote_port == tcphdr->src &&
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| 296 | pcb->local_port == tcphdr->dest &&
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| 297 | ip_addr_cmp(&pcb->remote_ip, ip_current_src_addr()) &&
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| 298 | ip_addr_cmp(&pcb->local_ip, ip_current_dest_addr())) {
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| 299 | /* We don't really care enough to move this PCB to the front
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| 300 | of the list since we are not very likely to receive that
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| 301 | many segments for connections in TIME-WAIT. */
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| 302 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packed for TIME_WAITing connection.\n"));
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| 303 | #ifdef LWIP_HOOK_TCP_INPACKET_PCB
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| 304 | if (LWIP_HOOK_TCP_INPACKET_PCB(pcb, tcphdr, tcphdr_optlen, tcphdr_opt1len,
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| 305 | tcphdr_opt2, p) == ERR_OK)
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| 306 | #endif
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| 307 | {
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| 308 | tcp_timewait_input(pcb);
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| 309 | }
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| 310 | pbuf_free(p);
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| 311 | return;
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| 312 | }
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| 313 | }
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| 314 |
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| 315 | /* Finally, if we still did not get a match, we check all PCBs that
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| 316 | are LISTENing for incoming connections. */
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| 317 | prev = NULL;
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| 318 | for (lpcb = tcp_listen_pcbs.listen_pcbs; lpcb != NULL; lpcb = lpcb->next) {
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| 319 | /* check if PCB is bound to specific netif */
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| 320 | if ((lpcb->netif_idx != NETIF_NO_INDEX) &&
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| 321 | (lpcb->netif_idx != netif_get_index(ip_data.current_input_netif))) {
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| 322 | prev = (struct tcp_pcb *)lpcb;
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| 323 | continue;
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| 324 | }
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| 325 |
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| 326 | if (lpcb->local_port == tcphdr->dest) {
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| 327 | if (IP_IS_ANY_TYPE_VAL(lpcb->local_ip)) {
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| 328 | /* found an ANY TYPE (IPv4/IPv6) match */
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| 329 | #if SO_REUSE
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| 330 | lpcb_any = lpcb;
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| 331 | lpcb_prev = prev;
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| 332 | #else /* SO_REUSE */
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| 333 | break;
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| 334 | #endif /* SO_REUSE */
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| 335 | } else if (IP_ADDR_PCB_VERSION_MATCH_EXACT(lpcb, ip_current_dest_addr())) {
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| 336 | if (ip_addr_cmp(&lpcb->local_ip, ip_current_dest_addr())) {
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| 337 | /* found an exact match */
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| 338 | break;
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| 339 | } else if (ip_addr_isany(&lpcb->local_ip)) {
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| 340 | /* found an ANY-match */
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| 341 | #if SO_REUSE
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| 342 | lpcb_any = lpcb;
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| 343 | lpcb_prev = prev;
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| 344 | #else /* SO_REUSE */
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| 345 | break;
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| 346 | #endif /* SO_REUSE */
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| 347 | }
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| 348 | }
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| 349 | }
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| 350 | prev = (struct tcp_pcb *)lpcb;
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| 351 | }
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| 352 | #if SO_REUSE
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| 353 | /* first try specific local IP */
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| 354 | if (lpcb == NULL) {
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| 355 | /* only pass to ANY if no specific local IP has been found */
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| 356 | lpcb = lpcb_any;
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| 357 | prev = lpcb_prev;
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| 358 | }
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| 359 | #endif /* SO_REUSE */
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| 360 | if (lpcb != NULL) {
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| 361 | /* Move this PCB to the front of the list so that subsequent
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| 362 | lookups will be faster (we exploit locality in TCP segment
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| 363 | arrivals). */
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| 364 | if (prev != NULL) {
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| 365 | ((struct tcp_pcb_listen *)prev)->next = lpcb->next;
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| 366 | /* our successor is the remainder of the listening list */
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| 367 | lpcb->next = tcp_listen_pcbs.listen_pcbs;
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| 368 | /* put this listening pcb at the head of the listening list */
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| 369 | tcp_listen_pcbs.listen_pcbs = lpcb;
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| 370 | } else {
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| 371 | TCP_STATS_INC(tcp.cachehit);
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| 372 | }
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| 373 |
|
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| 374 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packed for LISTENing connection.\n"));
|
---|
| 375 | #ifdef LWIP_HOOK_TCP_INPACKET_PCB
|
---|
| 376 | if (LWIP_HOOK_TCP_INPACKET_PCB((struct tcp_pcb *)lpcb, tcphdr, tcphdr_optlen,
|
---|
| 377 | tcphdr_opt1len, tcphdr_opt2, p) == ERR_OK)
|
---|
| 378 | #endif
|
---|
| 379 | {
|
---|
| 380 | tcp_listen_input(lpcb);
|
---|
| 381 | }
|
---|
| 382 | pbuf_free(p);
|
---|
| 383 | return;
|
---|
| 384 | }
|
---|
| 385 | }
|
---|
| 386 |
|
---|
| 387 | #if TCP_INPUT_DEBUG
|
---|
| 388 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("+-+-+-+-+-+-+-+-+-+-+-+-+-+- tcp_input: flags "));
|
---|
| 389 | tcp_debug_print_flags(TCPH_FLAGS(tcphdr));
|
---|
| 390 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("-+-+-+-+-+-+-+-+-+-+-+-+-+-+\n"));
|
---|
| 391 | #endif /* TCP_INPUT_DEBUG */
|
---|
| 392 |
|
---|
| 393 |
|
---|
| 394 | #ifdef LWIP_HOOK_TCP_INPACKET_PCB
|
---|
| 395 | if ((pcb != NULL) && LWIP_HOOK_TCP_INPACKET_PCB(pcb, tcphdr, tcphdr_optlen,
|
---|
| 396 | tcphdr_opt1len, tcphdr_opt2, p) != ERR_OK) {
|
---|
| 397 | pbuf_free(p);
|
---|
| 398 | return;
|
---|
| 399 | }
|
---|
| 400 | #endif
|
---|
| 401 | if (pcb != NULL) {
|
---|
| 402 | /* The incoming segment belongs to a connection. */
|
---|
| 403 | #if TCP_INPUT_DEBUG
|
---|
| 404 | tcp_debug_print_state(pcb->state);
|
---|
| 405 | #endif /* TCP_INPUT_DEBUG */
|
---|
| 406 |
|
---|
| 407 | /* Set up a tcp_seg structure. */
|
---|
| 408 | inseg.next = NULL;
|
---|
| 409 | inseg.len = p->tot_len;
|
---|
| 410 | inseg.p = p;
|
---|
| 411 | inseg.tcphdr = tcphdr;
|
---|
| 412 |
|
---|
| 413 | recv_data = NULL;
|
---|
| 414 | recv_flags = 0;
|
---|
| 415 | recv_acked = 0;
|
---|
| 416 |
|
---|
| 417 | if (flags & TCP_PSH) {
|
---|
| 418 | p->flags |= PBUF_FLAG_PUSH;
|
---|
| 419 | }
|
---|
| 420 |
|
---|
| 421 | /* If there is data which was previously "refused" by upper layer */
|
---|
| 422 | if (pcb->refused_data != NULL) {
|
---|
| 423 | if ((tcp_process_refused_data(pcb) == ERR_ABRT) ||
|
---|
| 424 | ((pcb->refused_data != NULL) && (tcplen > 0))) {
|
---|
| 425 | /* pcb has been aborted or refused data is still refused and the new
|
---|
| 426 | segment contains data */
|
---|
| 427 | if (pcb->rcv_ann_wnd == 0) {
|
---|
| 428 | /* this is a zero-window probe, we respond to it with current RCV.NXT
|
---|
| 429 | and drop the data segment */
|
---|
| 430 | tcp_send_empty_ack(pcb);
|
---|
| 431 | }
|
---|
| 432 | TCP_STATS_INC(tcp.drop);
|
---|
| 433 | MIB2_STATS_INC(mib2.tcpinerrs);
|
---|
| 434 | goto aborted;
|
---|
| 435 | }
|
---|
| 436 | }
|
---|
| 437 | tcp_input_pcb = pcb;
|
---|
| 438 | err = tcp_process(pcb);
|
---|
| 439 | /* A return value of ERR_ABRT means that tcp_abort() was called
|
---|
| 440 | and that the pcb has been freed. If so, we don't do anything. */
|
---|
| 441 | if (err != ERR_ABRT) {
|
---|
| 442 | if (recv_flags & TF_RESET) {
|
---|
| 443 | /* TF_RESET means that the connection was reset by the other
|
---|
| 444 | end. We then call the error callback to inform the
|
---|
| 445 | application that the connection is dead before we
|
---|
| 446 | deallocate the PCB. */
|
---|
| 447 | TCP_EVENT_ERR(pcb->state, pcb->errf, pcb->callback_arg, ERR_RST);
|
---|
| 448 | tcp_pcb_remove(&tcp_active_pcbs, pcb);
|
---|
| 449 | tcp_free(pcb);
|
---|
| 450 | } else {
|
---|
| 451 | err = ERR_OK;
|
---|
| 452 | /* If the application has registered a "sent" function to be
|
---|
| 453 | called when new send buffer space is available, we call it
|
---|
| 454 | now. */
|
---|
| 455 | if (recv_acked > 0) {
|
---|
| 456 | u16_t acked16;
|
---|
| 457 | #if LWIP_WND_SCALE
|
---|
| 458 | /* recv_acked is u32_t but the sent callback only takes a u16_t,
|
---|
| 459 | so we might have to call it multiple times. */
|
---|
| 460 | u32_t acked = recv_acked;
|
---|
| 461 | while (acked > 0) {
|
---|
| 462 | acked16 = (u16_t)LWIP_MIN(acked, 0xffffu);
|
---|
| 463 | acked -= acked16;
|
---|
| 464 | #else
|
---|
| 465 | {
|
---|
| 466 | acked16 = recv_acked;
|
---|
| 467 | #endif
|
---|
| 468 | TCP_EVENT_SENT(pcb, (u16_t)acked16, err);
|
---|
| 469 | if (err == ERR_ABRT) {
|
---|
| 470 | goto aborted;
|
---|
| 471 | }
|
---|
| 472 | }
|
---|
| 473 | recv_acked = 0;
|
---|
| 474 | }
|
---|
| 475 | if (tcp_input_delayed_close(pcb)) {
|
---|
| 476 | goto aborted;
|
---|
| 477 | }
|
---|
| 478 | #if TCP_QUEUE_OOSEQ && LWIP_WND_SCALE
|
---|
| 479 | while (recv_data != NULL) {
|
---|
| 480 | struct pbuf *rest = NULL;
|
---|
| 481 | pbuf_split_64k(recv_data, &rest);
|
---|
| 482 | #else /* TCP_QUEUE_OOSEQ && LWIP_WND_SCALE */
|
---|
| 483 | if (recv_data != NULL) {
|
---|
| 484 | #endif /* TCP_QUEUE_OOSEQ && LWIP_WND_SCALE */
|
---|
| 485 |
|
---|
| 486 | LWIP_ASSERT("pcb->refused_data == NULL", pcb->refused_data == NULL);
|
---|
| 487 | if (pcb->flags & TF_RXCLOSED) {
|
---|
| 488 | /* received data although already closed -> abort (send RST) to
|
---|
| 489 | notify the remote host that not all data has been processed */
|
---|
| 490 | pbuf_free(recv_data);
|
---|
| 491 | #if TCP_QUEUE_OOSEQ && LWIP_WND_SCALE
|
---|
| 492 | if (rest != NULL) {
|
---|
| 493 | pbuf_free(rest);
|
---|
| 494 | }
|
---|
| 495 | #endif /* TCP_QUEUE_OOSEQ && LWIP_WND_SCALE */
|
---|
| 496 | tcp_abort(pcb);
|
---|
| 497 | goto aborted;
|
---|
| 498 | }
|
---|
| 499 |
|
---|
| 500 | /* Notify application that data has been received. */
|
---|
| 501 | TCP_EVENT_RECV(pcb, recv_data, ERR_OK, err);
|
---|
| 502 | if (err == ERR_ABRT) {
|
---|
| 503 | #if TCP_QUEUE_OOSEQ && LWIP_WND_SCALE
|
---|
| 504 | if (rest != NULL) {
|
---|
| 505 | pbuf_free(rest);
|
---|
| 506 | }
|
---|
| 507 | #endif /* TCP_QUEUE_OOSEQ && LWIP_WND_SCALE */
|
---|
| 508 | goto aborted;
|
---|
| 509 | }
|
---|
| 510 |
|
---|
| 511 | /* If the upper layer can't receive this data, store it */
|
---|
| 512 | if (err != ERR_OK) {
|
---|
| 513 | #if TCP_QUEUE_OOSEQ && LWIP_WND_SCALE
|
---|
| 514 | if (rest != NULL) {
|
---|
| 515 | pbuf_cat(recv_data, rest);
|
---|
| 516 | }
|
---|
| 517 | #endif /* TCP_QUEUE_OOSEQ && LWIP_WND_SCALE */
|
---|
| 518 | pcb->refused_data = recv_data;
|
---|
| 519 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: keep incoming packet, because pcb is \"full\"\n"));
|
---|
| 520 | #if TCP_QUEUE_OOSEQ && LWIP_WND_SCALE
|
---|
| 521 | break;
|
---|
| 522 | } else {
|
---|
| 523 | /* Upper layer received the data, go on with the rest if > 64K */
|
---|
| 524 | recv_data = rest;
|
---|
| 525 | #endif /* TCP_QUEUE_OOSEQ && LWIP_WND_SCALE */
|
---|
| 526 | }
|
---|
| 527 | }
|
---|
| 528 |
|
---|
| 529 | /* If a FIN segment was received, we call the callback
|
---|
| 530 | function with a NULL buffer to indicate EOF. */
|
---|
| 531 | if (recv_flags & TF_GOT_FIN) {
|
---|
| 532 | if (pcb->refused_data != NULL) {
|
---|
| 533 | /* Delay this if we have refused data. */
|
---|
| 534 | pcb->refused_data->flags |= PBUF_FLAG_TCP_FIN;
|
---|
| 535 | } else {
|
---|
| 536 | /* correct rcv_wnd as the application won't call tcp_recved()
|
---|
| 537 | for the FIN's seqno */
|
---|
| 538 | if (pcb->rcv_wnd != TCP_WND_MAX(pcb)) {
|
---|
| 539 | pcb->rcv_wnd++;
|
---|
| 540 | }
|
---|
| 541 | TCP_EVENT_CLOSED(pcb, err);
|
---|
| 542 | if (err == ERR_ABRT) {
|
---|
| 543 | goto aborted;
|
---|
| 544 | }
|
---|
| 545 | }
|
---|
| 546 | }
|
---|
| 547 |
|
---|
| 548 | tcp_input_pcb = NULL;
|
---|
| 549 | if (tcp_input_delayed_close(pcb)) {
|
---|
| 550 | goto aborted;
|
---|
| 551 | }
|
---|
| 552 | /* Try to send something out. */
|
---|
| 553 | tcp_output(pcb);
|
---|
| 554 | #if TCP_INPUT_DEBUG
|
---|
| 555 | #if TCP_DEBUG
|
---|
| 556 | tcp_debug_print_state(pcb->state);
|
---|
| 557 | #endif /* TCP_DEBUG */
|
---|
| 558 | #endif /* TCP_INPUT_DEBUG */
|
---|
| 559 | }
|
---|
| 560 | }
|
---|
| 561 | /* Jump target if pcb has been aborted in a callback (by calling tcp_abort()).
|
---|
| 562 | Below this line, 'pcb' may not be dereferenced! */
|
---|
| 563 | aborted:
|
---|
| 564 | tcp_input_pcb = NULL;
|
---|
| 565 | recv_data = NULL;
|
---|
| 566 |
|
---|
| 567 | /* give up our reference to inseg.p */
|
---|
| 568 | if (inseg.p != NULL) {
|
---|
| 569 | pbuf_free(inseg.p);
|
---|
| 570 | inseg.p = NULL;
|
---|
| 571 | }
|
---|
| 572 | } else {
|
---|
| 573 | /* If no matching PCB was found, send a TCP RST (reset) to the
|
---|
| 574 | sender. */
|
---|
| 575 | LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_input: no PCB match found, resetting.\n"));
|
---|
| 576 | if (!(TCPH_FLAGS(tcphdr) & TCP_RST)) {
|
---|
| 577 | TCP_STATS_INC(tcp.proterr);
|
---|
| 578 | TCP_STATS_INC(tcp.drop);
|
---|
| 579 | tcp_rst(NULL, ackno, seqno + tcplen, ip_current_dest_addr(),
|
---|
| 580 | ip_current_src_addr(), tcphdr->dest, tcphdr->src);
|
---|
| 581 | }
|
---|
| 582 | pbuf_free(p);
|
---|
| 583 | }
|
---|
| 584 |
|
---|
| 585 | LWIP_ASSERT("tcp_input: tcp_pcbs_sane()", tcp_pcbs_sane());
|
---|
| 586 | PERF_STOP("tcp_input");
|
---|
| 587 | return;
|
---|
| 588 | dropped:
|
---|
| 589 | TCP_STATS_INC(tcp.drop);
|
---|
| 590 | MIB2_STATS_INC(mib2.tcpinerrs);
|
---|
| 591 | pbuf_free(p);
|
---|
| 592 | }
|
---|
| 593 |
|
---|
| 594 | /** Called from tcp_input to check for TF_CLOSED flag. This results in closing
|
---|
| 595 | * and deallocating a pcb at the correct place to ensure noone references it
|
---|
| 596 | * any more.
|
---|
| 597 | * @returns 1 if the pcb has been closed and deallocated, 0 otherwise
|
---|
| 598 | */
|
---|
| 599 | static int
|
---|
| 600 | tcp_input_delayed_close(struct tcp_pcb *pcb)
|
---|
| 601 | {
|
---|
| 602 | LWIP_ASSERT("tcp_input_delayed_close: invalid pcb", pcb != NULL);
|
---|
| 603 |
|
---|
| 604 | if (recv_flags & TF_CLOSED) {
|
---|
| 605 | /* The connection has been closed and we will deallocate the
|
---|
| 606 | PCB. */
|
---|
| 607 | if (!(pcb->flags & TF_RXCLOSED)) {
|
---|
| 608 | /* Connection closed although the application has only shut down the
|
---|
| 609 | tx side: call the PCB's err callback and indicate the closure to
|
---|
| 610 | ensure the application doesn't continue using the PCB. */
|
---|
| 611 | TCP_EVENT_ERR(pcb->state, pcb->errf, pcb->callback_arg, ERR_CLSD);
|
---|
| 612 | }
|
---|
| 613 | tcp_pcb_remove(&tcp_active_pcbs, pcb);
|
---|
| 614 | tcp_free(pcb);
|
---|
| 615 | return 1;
|
---|
| 616 | }
|
---|
| 617 | return 0;
|
---|
| 618 | }
|
---|
| 619 |
|
---|
| 620 | /**
|
---|
| 621 | * Called by tcp_input() when a segment arrives for a listening
|
---|
| 622 | * connection (from tcp_input()).
|
---|
| 623 | *
|
---|
| 624 | * @param pcb the tcp_pcb_listen for which a segment arrived
|
---|
| 625 | *
|
---|
| 626 | * @note the segment which arrived is saved in global variables, therefore only the pcb
|
---|
| 627 | * involved is passed as a parameter to this function
|
---|
| 628 | */
|
---|
| 629 | static void
|
---|
| 630 | tcp_listen_input(struct tcp_pcb_listen *pcb)
|
---|
| 631 | {
|
---|
| 632 | struct tcp_pcb *npcb;
|
---|
| 633 | u32_t iss;
|
---|
| 634 | err_t rc;
|
---|
| 635 |
|
---|
| 636 | if (flags & TCP_RST) {
|
---|
| 637 | /* An incoming RST should be ignored. Return. */
|
---|
| 638 | return;
|
---|
| 639 | }
|
---|
| 640 |
|
---|
| 641 | LWIP_ASSERT("tcp_listen_input: invalid pcb", pcb != NULL);
|
---|
| 642 |
|
---|
| 643 | /* In the LISTEN state, we check for incoming SYN segments,
|
---|
| 644 | creates a new PCB, and responds with a SYN|ACK. */
|
---|
| 645 | if (flags & TCP_ACK) {
|
---|
| 646 | /* For incoming segments with the ACK flag set, respond with a
|
---|
| 647 | RST. */
|
---|
| 648 | LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_listen_input: ACK in LISTEN, sending reset\n"));
|
---|
| 649 | tcp_rst((const struct tcp_pcb *)pcb, ackno, seqno + tcplen, ip_current_dest_addr(),
|
---|
| 650 | ip_current_src_addr(), tcphdr->dest, tcphdr->src);
|
---|
| 651 | } else if (flags & TCP_SYN) {
|
---|
| 652 | LWIP_DEBUGF(TCP_DEBUG, ("TCP connection request %"U16_F" -> %"U16_F".\n", tcphdr->src, tcphdr->dest));
|
---|
| 653 | #if TCP_LISTEN_BACKLOG
|
---|
| 654 | if (pcb->accepts_pending >= pcb->backlog) {
|
---|
| 655 | LWIP_DEBUGF(TCP_DEBUG, ("tcp_listen_input: listen backlog exceeded for port %"U16_F"\n", tcphdr->dest));
|
---|
| 656 | return;
|
---|
| 657 | }
|
---|
| 658 | #endif /* TCP_LISTEN_BACKLOG */
|
---|
| 659 | npcb = tcp_alloc(pcb->prio);
|
---|
| 660 | /* If a new PCB could not be created (probably due to lack of memory),
|
---|
| 661 | we don't do anything, but rely on the sender will retransmit the
|
---|
| 662 | SYN at a time when we have more memory available. */
|
---|
| 663 | if (npcb == NULL) {
|
---|
| 664 | err_t err;
|
---|
| 665 | LWIP_DEBUGF(TCP_DEBUG, ("tcp_listen_input: could not allocate PCB\n"));
|
---|
| 666 | TCP_STATS_INC(tcp.memerr);
|
---|
| 667 | TCP_EVENT_ACCEPT(pcb, NULL, pcb->callback_arg, ERR_MEM, err);
|
---|
| 668 | LWIP_UNUSED_ARG(err); /* err not useful here */
|
---|
| 669 | return;
|
---|
| 670 | }
|
---|
| 671 | #if TCP_LISTEN_BACKLOG
|
---|
| 672 | pcb->accepts_pending++;
|
---|
| 673 | tcp_set_flags(npcb, TF_BACKLOGPEND);
|
---|
| 674 | #endif /* TCP_LISTEN_BACKLOG */
|
---|
| 675 | /* Set up the new PCB. */
|
---|
| 676 | ip_addr_copy(npcb->local_ip, *ip_current_dest_addr());
|
---|
| 677 | ip_addr_copy(npcb->remote_ip, *ip_current_src_addr());
|
---|
| 678 | npcb->local_port = pcb->local_port;
|
---|
| 679 | npcb->remote_port = tcphdr->src;
|
---|
| 680 | npcb->state = SYN_RCVD;
|
---|
| 681 | npcb->rcv_nxt = seqno + 1;
|
---|
| 682 | npcb->rcv_ann_right_edge = npcb->rcv_nxt;
|
---|
| 683 | iss = tcp_next_iss(npcb);
|
---|
| 684 | npcb->snd_wl2 = iss;
|
---|
| 685 | npcb->snd_nxt = iss;
|
---|
| 686 | npcb->lastack = iss;
|
---|
| 687 | npcb->snd_lbb = iss;
|
---|
| 688 | npcb->snd_wl1 = seqno - 1;/* initialise to seqno-1 to force window update */
|
---|
| 689 | npcb->callback_arg = pcb->callback_arg;
|
---|
| 690 | #if LWIP_CALLBACK_API || TCP_LISTEN_BACKLOG
|
---|
| 691 | npcb->listener = pcb;
|
---|
| 692 | #endif /* LWIP_CALLBACK_API || TCP_LISTEN_BACKLOG */
|
---|
| 693 | /* inherit socket options */
|
---|
| 694 | npcb->so_options = pcb->so_options & SOF_INHERITED;
|
---|
| 695 | npcb->netif_idx = pcb->netif_idx;
|
---|
| 696 | /* Register the new PCB so that we can begin receiving segments
|
---|
| 697 | for it. */
|
---|
| 698 | TCP_REG_ACTIVE(npcb);
|
---|
| 699 |
|
---|
| 700 | /* Parse any options in the SYN. */
|
---|
| 701 | tcp_parseopt(npcb);
|
---|
| 702 | npcb->snd_wnd = tcphdr->wnd;
|
---|
| 703 | npcb->snd_wnd_max = npcb->snd_wnd;
|
---|
| 704 |
|
---|
| 705 | #if TCP_CALCULATE_EFF_SEND_MSS
|
---|
| 706 | npcb->mss = tcp_eff_send_mss(npcb->mss, &npcb->local_ip, &npcb->remote_ip);
|
---|
| 707 | #endif /* TCP_CALCULATE_EFF_SEND_MSS */
|
---|
| 708 |
|
---|
| 709 | MIB2_STATS_INC(mib2.tcppassiveopens);
|
---|
| 710 |
|
---|
| 711 | #if LWIP_TCP_PCB_NUM_EXT_ARGS
|
---|
| 712 | if (tcp_ext_arg_invoke_callbacks_passive_open(pcb, npcb) != ERR_OK) {
|
---|
| 713 | tcp_abandon(npcb, 0);
|
---|
| 714 | return;
|
---|
| 715 | }
|
---|
| 716 | #endif
|
---|
| 717 |
|
---|
| 718 | /* Send a SYN|ACK together with the MSS option. */
|
---|
| 719 | rc = tcp_enqueue_flags(npcb, TCP_SYN | TCP_ACK);
|
---|
| 720 | if (rc != ERR_OK) {
|
---|
| 721 | tcp_abandon(npcb, 0);
|
---|
| 722 | return;
|
---|
| 723 | }
|
---|
| 724 | tcp_output(npcb);
|
---|
| 725 | }
|
---|
| 726 | return;
|
---|
| 727 | }
|
---|
| 728 |
|
---|
| 729 | /**
|
---|
| 730 | * Called by tcp_input() when a segment arrives for a connection in
|
---|
| 731 | * TIME_WAIT.
|
---|
| 732 | *
|
---|
| 733 | * @param pcb the tcp_pcb for which a segment arrived
|
---|
| 734 | *
|
---|
| 735 | * @note the segment which arrived is saved in global variables, therefore only the pcb
|
---|
| 736 | * involved is passed as a parameter to this function
|
---|
| 737 | */
|
---|
| 738 | static void
|
---|
| 739 | tcp_timewait_input(struct tcp_pcb *pcb)
|
---|
| 740 | {
|
---|
| 741 | /* RFC 1337: in TIME_WAIT, ignore RST and ACK FINs + any 'acceptable' segments */
|
---|
| 742 | /* RFC 793 3.9 Event Processing - Segment Arrives:
|
---|
| 743 | * - first check sequence number - we skip that one in TIME_WAIT (always
|
---|
| 744 | * acceptable since we only send ACKs)
|
---|
| 745 | * - second check the RST bit (... return) */
|
---|
| 746 | if (flags & TCP_RST) {
|
---|
| 747 | return;
|
---|
| 748 | }
|
---|
| 749 |
|
---|
| 750 | LWIP_ASSERT("tcp_timewait_input: invalid pcb", pcb != NULL);
|
---|
| 751 |
|
---|
| 752 | /* - fourth, check the SYN bit, */
|
---|
| 753 | if (flags & TCP_SYN) {
|
---|
| 754 | /* If an incoming segment is not acceptable, an acknowledgment
|
---|
| 755 | should be sent in reply */
|
---|
| 756 | if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt, pcb->rcv_nxt + pcb->rcv_wnd)) {
|
---|
| 757 | /* If the SYN is in the window it is an error, send a reset */
|
---|
| 758 | tcp_rst(pcb, ackno, seqno + tcplen, ip_current_dest_addr(),
|
---|
| 759 | ip_current_src_addr(), tcphdr->dest, tcphdr->src);
|
---|
| 760 | return;
|
---|
| 761 | }
|
---|
| 762 | } else if (flags & TCP_FIN) {
|
---|
| 763 | /* - eighth, check the FIN bit: Remain in the TIME-WAIT state.
|
---|
| 764 | Restart the 2 MSL time-wait timeout.*/
|
---|
| 765 | pcb->tmr = tcp_ticks;
|
---|
| 766 | }
|
---|
| 767 |
|
---|
| 768 | if ((tcplen > 0)) {
|
---|
| 769 | /* Acknowledge data, FIN or out-of-window SYN */
|
---|
| 770 | tcp_ack_now(pcb);
|
---|
| 771 | tcp_output(pcb);
|
---|
| 772 | }
|
---|
| 773 | return;
|
---|
| 774 | }
|
---|
| 775 |
|
---|
| 776 | /**
|
---|
| 777 | * Implements the TCP state machine. Called by tcp_input. In some
|
---|
| 778 | * states tcp_receive() is called to receive data. The tcp_seg
|
---|
| 779 | * argument will be freed by the caller (tcp_input()) unless the
|
---|
| 780 | * recv_data pointer in the pcb is set.
|
---|
| 781 | *
|
---|
| 782 | * @param pcb the tcp_pcb for which a segment arrived
|
---|
| 783 | *
|
---|
| 784 | * @note the segment which arrived is saved in global variables, therefore only the pcb
|
---|
| 785 | * involved is passed as a parameter to this function
|
---|
| 786 | */
|
---|
| 787 | static err_t
|
---|
| 788 | tcp_process(struct tcp_pcb *pcb)
|
---|
| 789 | {
|
---|
| 790 | struct tcp_seg *rseg;
|
---|
| 791 | u8_t acceptable = 0;
|
---|
| 792 | err_t err;
|
---|
| 793 |
|
---|
| 794 | err = ERR_OK;
|
---|
| 795 |
|
---|
| 796 | LWIP_ASSERT("tcp_process: invalid pcb", pcb != NULL);
|
---|
| 797 |
|
---|
| 798 | /* Process incoming RST segments. */
|
---|
| 799 | if (flags & TCP_RST) {
|
---|
| 800 | /* First, determine if the reset is acceptable. */
|
---|
| 801 | if (pcb->state == SYN_SENT) {
|
---|
| 802 | /* "In the SYN-SENT state (a RST received in response to an initial SYN),
|
---|
| 803 | the RST is acceptable if the ACK field acknowledges the SYN." */
|
---|
| 804 | if (ackno == pcb->snd_nxt) {
|
---|
| 805 | acceptable = 1;
|
---|
| 806 | }
|
---|
| 807 | } else {
|
---|
| 808 | /* "In all states except SYN-SENT, all reset (RST) segments are validated
|
---|
| 809 | by checking their SEQ-fields." */
|
---|
| 810 | if (seqno == pcb->rcv_nxt) {
|
---|
| 811 | acceptable = 1;
|
---|
| 812 | } else if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt,
|
---|
| 813 | pcb->rcv_nxt + pcb->rcv_wnd)) {
|
---|
| 814 | /* If the sequence number is inside the window, we send a challenge ACK
|
---|
| 815 | and wait for a re-send with matching sequence number.
|
---|
| 816 | This follows RFC 5961 section 3.2 and addresses CVE-2004-0230
|
---|
| 817 | (RST spoofing attack), which is present in RFC 793 RST handling. */
|
---|
| 818 | tcp_ack_now(pcb);
|
---|
| 819 | }
|
---|
| 820 | }
|
---|
| 821 |
|
---|
| 822 | if (acceptable) {
|
---|
| 823 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_process: Connection RESET\n"));
|
---|
| 824 | LWIP_ASSERT("tcp_input: pcb->state != CLOSED", pcb->state != CLOSED);
|
---|
| 825 | recv_flags |= TF_RESET;
|
---|
| 826 | tcp_clear_flags(pcb, TF_ACK_DELAY);
|
---|
| 827 | return ERR_RST;
|
---|
| 828 | } else {
|
---|
| 829 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_process: unacceptable reset seqno %"U32_F" rcv_nxt %"U32_F"\n",
|
---|
| 830 | seqno, pcb->rcv_nxt));
|
---|
| 831 | LWIP_DEBUGF(TCP_DEBUG, ("tcp_process: unacceptable reset seqno %"U32_F" rcv_nxt %"U32_F"\n",
|
---|
| 832 | seqno, pcb->rcv_nxt));
|
---|
| 833 | return ERR_OK;
|
---|
| 834 | }
|
---|
| 835 | }
|
---|
| 836 |
|
---|
| 837 | if ((flags & TCP_SYN) && (pcb->state != SYN_SENT && pcb->state != SYN_RCVD)) {
|
---|
| 838 | /* Cope with new connection attempt after remote end crashed */
|
---|
| 839 | tcp_ack_now(pcb);
|
---|
| 840 | return ERR_OK;
|
---|
| 841 | }
|
---|
| 842 |
|
---|
| 843 | if ((pcb->flags & TF_RXCLOSED) == 0) {
|
---|
| 844 | /* Update the PCB (in)activity timer unless rx is closed (see tcp_shutdown) */
|
---|
| 845 | pcb->tmr = tcp_ticks;
|
---|
| 846 | }
|
---|
| 847 | pcb->keep_cnt_sent = 0;
|
---|
| 848 | pcb->persist_probe = 0;
|
---|
| 849 |
|
---|
| 850 | tcp_parseopt(pcb);
|
---|
| 851 |
|
---|
| 852 | /* Do different things depending on the TCP state. */
|
---|
| 853 | switch (pcb->state) {
|
---|
| 854 | case SYN_SENT:
|
---|
| 855 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("SYN-SENT: ackno %"U32_F" pcb->snd_nxt %"U32_F" unacked %"U32_F"\n", ackno,
|
---|
| 856 | pcb->snd_nxt, lwip_ntohl(pcb->unacked->tcphdr->seqno)));
|
---|
| 857 | /* received SYN ACK with expected sequence number? */
|
---|
| 858 | if ((flags & TCP_ACK) && (flags & TCP_SYN)
|
---|
| 859 | && (ackno == pcb->lastack + 1)) {
|
---|
| 860 | pcb->rcv_nxt = seqno + 1;
|
---|
| 861 | pcb->rcv_ann_right_edge = pcb->rcv_nxt;
|
---|
| 862 | pcb->lastack = ackno;
|
---|
| 863 | pcb->snd_wnd = tcphdr->wnd;
|
---|
| 864 | pcb->snd_wnd_max = pcb->snd_wnd;
|
---|
| 865 | pcb->snd_wl1 = seqno - 1; /* initialise to seqno - 1 to force window update */
|
---|
| 866 | pcb->state = ESTABLISHED;
|
---|
| 867 |
|
---|
| 868 | #if TCP_CALCULATE_EFF_SEND_MSS
|
---|
| 869 | pcb->mss = tcp_eff_send_mss(pcb->mss, &pcb->local_ip, &pcb->remote_ip);
|
---|
| 870 | #endif /* TCP_CALCULATE_EFF_SEND_MSS */
|
---|
| 871 |
|
---|
| 872 | pcb->cwnd = LWIP_TCP_CALC_INITIAL_CWND(pcb->mss);
|
---|
| 873 | LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_process (SENT): cwnd %"TCPWNDSIZE_F
|
---|
| 874 | " ssthresh %"TCPWNDSIZE_F"\n",
|
---|
| 875 | pcb->cwnd, pcb->ssthresh));
|
---|
| 876 | LWIP_ASSERT("pcb->snd_queuelen > 0", (pcb->snd_queuelen > 0));
|
---|
| 877 | --pcb->snd_queuelen;
|
---|
| 878 | LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_process: SYN-SENT --queuelen %"TCPWNDSIZE_F"\n", (tcpwnd_size_t)pcb->snd_queuelen));
|
---|
| 879 | rseg = pcb->unacked;
|
---|
| 880 | if (rseg == NULL) {
|
---|
| 881 | /* might happen if tcp_output fails in tcp_rexmit_rto()
|
---|
| 882 | in which case the segment is on the unsent list */
|
---|
| 883 | rseg = pcb->unsent;
|
---|
| 884 | LWIP_ASSERT("no segment to free", rseg != NULL);
|
---|
| 885 | pcb->unsent = rseg->next;
|
---|
| 886 | } else {
|
---|
| 887 | pcb->unacked = rseg->next;
|
---|
| 888 | }
|
---|
| 889 | tcp_seg_free(rseg);
|
---|
| 890 |
|
---|
| 891 | /* If there's nothing left to acknowledge, stop the retransmit
|
---|
| 892 | timer, otherwise reset it to start again */
|
---|
| 893 | if (pcb->unacked == NULL) {
|
---|
| 894 | pcb->rtime = -1;
|
---|
| 895 | } else {
|
---|
| 896 | pcb->rtime = 0;
|
---|
| 897 | pcb->nrtx = 0;
|
---|
| 898 | }
|
---|
| 899 |
|
---|
| 900 | /* Call the user specified function to call when successfully
|
---|
| 901 | * connected. */
|
---|
| 902 | TCP_EVENT_CONNECTED(pcb, ERR_OK, err);
|
---|
| 903 | if (err == ERR_ABRT) {
|
---|
| 904 | return ERR_ABRT;
|
---|
| 905 | }
|
---|
| 906 | tcp_ack_now(pcb);
|
---|
| 907 | }
|
---|
| 908 | /* received ACK? possibly a half-open connection */
|
---|
| 909 | else if (flags & TCP_ACK) {
|
---|
| 910 | /* send a RST to bring the other side in a non-synchronized state. */
|
---|
| 911 | tcp_rst(pcb, ackno, seqno + tcplen, ip_current_dest_addr(),
|
---|
| 912 | ip_current_src_addr(), tcphdr->dest, tcphdr->src);
|
---|
| 913 | /* Resend SYN immediately (don't wait for rto timeout) to establish
|
---|
| 914 | connection faster, but do not send more SYNs than we otherwise would
|
---|
| 915 | have, or we might get caught in a loop on loopback interfaces. */
|
---|
| 916 | if (pcb->nrtx < TCP_SYNMAXRTX) {
|
---|
| 917 | pcb->rtime = 0;
|
---|
| 918 | tcp_rexmit_rto(pcb);
|
---|
| 919 | }
|
---|
| 920 | }
|
---|
| 921 | break;
|
---|
| 922 | case SYN_RCVD:
|
---|
| 923 | if (flags & TCP_ACK) {
|
---|
| 924 | /* expected ACK number? */
|
---|
| 925 | if (TCP_SEQ_BETWEEN(ackno, pcb->lastack + 1, pcb->snd_nxt)) {
|
---|
| 926 | pcb->state = ESTABLISHED;
|
---|
| 927 | LWIP_DEBUGF(TCP_DEBUG, ("TCP connection established %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
|
---|
| 928 | #if LWIP_CALLBACK_API || TCP_LISTEN_BACKLOG
|
---|
| 929 | if (pcb->listener == NULL) {
|
---|
| 930 | /* listen pcb might be closed by now */
|
---|
| 931 | err = ERR_VAL;
|
---|
| 932 | } else
|
---|
| 933 | #endif /* LWIP_CALLBACK_API || TCP_LISTEN_BACKLOG */
|
---|
| 934 | {
|
---|
| 935 | #if LWIP_CALLBACK_API
|
---|
| 936 | LWIP_ASSERT("pcb->listener->accept != NULL", pcb->listener->accept != NULL);
|
---|
| 937 | #endif
|
---|
| 938 | tcp_backlog_accepted(pcb);
|
---|
| 939 | /* Call the accept function. */
|
---|
| 940 | TCP_EVENT_ACCEPT(pcb->listener, pcb, pcb->callback_arg, ERR_OK, err);
|
---|
| 941 | }
|
---|
| 942 | if (err != ERR_OK) {
|
---|
| 943 | /* If the accept function returns with an error, we abort
|
---|
| 944 | * the connection. */
|
---|
| 945 | /* Already aborted? */
|
---|
| 946 | if (err != ERR_ABRT) {
|
---|
| 947 | tcp_abort(pcb);
|
---|
| 948 | }
|
---|
| 949 | return ERR_ABRT;
|
---|
| 950 | }
|
---|
| 951 | /* If there was any data contained within this ACK,
|
---|
| 952 | * we'd better pass it on to the application as well. */
|
---|
| 953 | tcp_receive(pcb);
|
---|
| 954 |
|
---|
| 955 | /* Prevent ACK for SYN to generate a sent event */
|
---|
| 956 | if (recv_acked != 0) {
|
---|
| 957 | recv_acked--;
|
---|
| 958 | }
|
---|
| 959 |
|
---|
| 960 | pcb->cwnd = LWIP_TCP_CALC_INITIAL_CWND(pcb->mss);
|
---|
| 961 | LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_process (SYN_RCVD): cwnd %"TCPWNDSIZE_F
|
---|
| 962 | " ssthresh %"TCPWNDSIZE_F"\n",
|
---|
| 963 | pcb->cwnd, pcb->ssthresh));
|
---|
| 964 |
|
---|
| 965 | if (recv_flags & TF_GOT_FIN) {
|
---|
| 966 | tcp_ack_now(pcb);
|
---|
| 967 | pcb->state = CLOSE_WAIT;
|
---|
| 968 | }
|
---|
| 969 | } else {
|
---|
| 970 | /* incorrect ACK number, send RST */
|
---|
| 971 | tcp_rst(pcb, ackno, seqno + tcplen, ip_current_dest_addr(),
|
---|
| 972 | ip_current_src_addr(), tcphdr->dest, tcphdr->src);
|
---|
| 973 | }
|
---|
| 974 | } else if ((flags & TCP_SYN) && (seqno == pcb->rcv_nxt - 1)) {
|
---|
| 975 | /* Looks like another copy of the SYN - retransmit our SYN-ACK */
|
---|
| 976 | tcp_rexmit(pcb);
|
---|
| 977 | }
|
---|
| 978 | break;
|
---|
| 979 | case CLOSE_WAIT:
|
---|
| 980 | /* FALLTHROUGH */
|
---|
| 981 | case ESTABLISHED:
|
---|
| 982 | tcp_receive(pcb);
|
---|
| 983 | if (recv_flags & TF_GOT_FIN) { /* passive close */
|
---|
| 984 | tcp_ack_now(pcb);
|
---|
| 985 | pcb->state = CLOSE_WAIT;
|
---|
| 986 | }
|
---|
| 987 | break;
|
---|
| 988 | case FIN_WAIT_1:
|
---|
| 989 | tcp_receive(pcb);
|
---|
| 990 | if (recv_flags & TF_GOT_FIN) {
|
---|
| 991 | if ((flags & TCP_ACK) && (ackno == pcb->snd_nxt) &&
|
---|
| 992 | pcb->unsent == NULL) {
|
---|
| 993 | LWIP_DEBUGF(TCP_DEBUG,
|
---|
| 994 | ("TCP connection closed: FIN_WAIT_1 %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
|
---|
| 995 | tcp_ack_now(pcb);
|
---|
| 996 | tcp_pcb_purge(pcb);
|
---|
| 997 | TCP_RMV_ACTIVE(pcb);
|
---|
| 998 | pcb->state = TIME_WAIT;
|
---|
| 999 | TCP_REG(&tcp_tw_pcbs, pcb);
|
---|
| 1000 | } else {
|
---|
| 1001 | tcp_ack_now(pcb);
|
---|
| 1002 | pcb->state = CLOSING;
|
---|
| 1003 | }
|
---|
| 1004 | } else if ((flags & TCP_ACK) && (ackno == pcb->snd_nxt) &&
|
---|
| 1005 | pcb->unsent == NULL) {
|
---|
| 1006 | pcb->state = FIN_WAIT_2;
|
---|
| 1007 | }
|
---|
| 1008 | break;
|
---|
| 1009 | case FIN_WAIT_2:
|
---|
| 1010 | tcp_receive(pcb);
|
---|
| 1011 | if (recv_flags & TF_GOT_FIN) {
|
---|
| 1012 | LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: FIN_WAIT_2 %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
|
---|
| 1013 | tcp_ack_now(pcb);
|
---|
| 1014 | tcp_pcb_purge(pcb);
|
---|
| 1015 | TCP_RMV_ACTIVE(pcb);
|
---|
| 1016 | pcb->state = TIME_WAIT;
|
---|
| 1017 | TCP_REG(&tcp_tw_pcbs, pcb);
|
---|
| 1018 | }
|
---|
| 1019 | break;
|
---|
| 1020 | case CLOSING:
|
---|
| 1021 | tcp_receive(pcb);
|
---|
| 1022 | if ((flags & TCP_ACK) && ackno == pcb->snd_nxt && pcb->unsent == NULL) {
|
---|
| 1023 | LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: CLOSING %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
|
---|
| 1024 | tcp_pcb_purge(pcb);
|
---|
| 1025 | TCP_RMV_ACTIVE(pcb);
|
---|
| 1026 | pcb->state = TIME_WAIT;
|
---|
| 1027 | TCP_REG(&tcp_tw_pcbs, pcb);
|
---|
| 1028 | }
|
---|
| 1029 | break;
|
---|
| 1030 | case LAST_ACK:
|
---|
| 1031 | tcp_receive(pcb);
|
---|
| 1032 | if ((flags & TCP_ACK) && ackno == pcb->snd_nxt && pcb->unsent == NULL) {
|
---|
| 1033 | LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: LAST_ACK %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
|
---|
| 1034 | /* bugfix #21699: don't set pcb->state to CLOSED here or we risk leaking segments */
|
---|
| 1035 | recv_flags |= TF_CLOSED;
|
---|
| 1036 | }
|
---|
| 1037 | break;
|
---|
| 1038 | default:
|
---|
| 1039 | break;
|
---|
| 1040 | }
|
---|
| 1041 | return ERR_OK;
|
---|
| 1042 | }
|
---|
| 1043 |
|
---|
| 1044 | #if TCP_QUEUE_OOSEQ
|
---|
| 1045 | /**
|
---|
| 1046 | * Insert segment into the list (segments covered with new one will be deleted)
|
---|
| 1047 | *
|
---|
| 1048 | * Called from tcp_receive()
|
---|
| 1049 | */
|
---|
| 1050 | static void
|
---|
| 1051 | tcp_oos_insert_segment(struct tcp_seg *cseg, struct tcp_seg *next)
|
---|
| 1052 | {
|
---|
| 1053 | struct tcp_seg *old_seg;
|
---|
| 1054 |
|
---|
| 1055 | LWIP_ASSERT("tcp_oos_insert_segment: invalid cseg", cseg != NULL);
|
---|
| 1056 |
|
---|
| 1057 | if (TCPH_FLAGS(cseg->tcphdr) & TCP_FIN) {
|
---|
| 1058 | /* received segment overlaps all following segments */
|
---|
| 1059 | tcp_segs_free(next);
|
---|
| 1060 | next = NULL;
|
---|
| 1061 | } else {
|
---|
| 1062 | /* delete some following segments
|
---|
| 1063 | oos queue may have segments with FIN flag */
|
---|
| 1064 | while (next &&
|
---|
| 1065 | TCP_SEQ_GEQ((seqno + cseg->len),
|
---|
| 1066 | (next->tcphdr->seqno + next->len))) {
|
---|
| 1067 | /* cseg with FIN already processed */
|
---|
| 1068 | if (TCPH_FLAGS(next->tcphdr) & TCP_FIN) {
|
---|
| 1069 | TCPH_SET_FLAG(cseg->tcphdr, TCP_FIN);
|
---|
| 1070 | }
|
---|
| 1071 | old_seg = next;
|
---|
| 1072 | next = next->next;
|
---|
| 1073 | tcp_seg_free(old_seg);
|
---|
| 1074 | }
|
---|
| 1075 | if (next &&
|
---|
| 1076 | TCP_SEQ_GT(seqno + cseg->len, next->tcphdr->seqno)) {
|
---|
| 1077 | /* We need to trim the incoming segment. */
|
---|
| 1078 | cseg->len = (u16_t)(next->tcphdr->seqno - seqno);
|
---|
| 1079 | pbuf_realloc(cseg->p, cseg->len);
|
---|
| 1080 | }
|
---|
| 1081 | }
|
---|
| 1082 | cseg->next = next;
|
---|
| 1083 | }
|
---|
| 1084 | #endif /* TCP_QUEUE_OOSEQ */
|
---|
| 1085 |
|
---|
| 1086 | /** Remove segments from a list if the incoming ACK acknowledges them */
|
---|
| 1087 | static struct tcp_seg *
|
---|
| 1088 | tcp_free_acked_segments(struct tcp_pcb *pcb, struct tcp_seg *seg_list, const char *dbg_list_name,
|
---|
| 1089 | struct tcp_seg *dbg_other_seg_list)
|
---|
| 1090 | {
|
---|
| 1091 | struct tcp_seg *next;
|
---|
| 1092 | u16_t clen;
|
---|
| 1093 |
|
---|
| 1094 | LWIP_UNUSED_ARG(dbg_list_name);
|
---|
| 1095 | LWIP_UNUSED_ARG(dbg_other_seg_list);
|
---|
| 1096 |
|
---|
| 1097 | while (seg_list != NULL &&
|
---|
| 1098 | TCP_SEQ_LEQ(lwip_ntohl(seg_list->tcphdr->seqno) +
|
---|
| 1099 | TCP_TCPLEN(seg_list), ackno)) {
|
---|
| 1100 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: removing %"U32_F":%"U32_F" from pcb->%s\n",
|
---|
| 1101 | lwip_ntohl(seg_list->tcphdr->seqno),
|
---|
| 1102 | lwip_ntohl(seg_list->tcphdr->seqno) + TCP_TCPLEN(seg_list),
|
---|
| 1103 | dbg_list_name));
|
---|
| 1104 |
|
---|
| 1105 | next = seg_list;
|
---|
| 1106 | seg_list = seg_list->next;
|
---|
| 1107 |
|
---|
| 1108 | clen = pbuf_clen(next->p);
|
---|
| 1109 | LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_receive: queuelen %"TCPWNDSIZE_F" ... ",
|
---|
| 1110 | (tcpwnd_size_t)pcb->snd_queuelen));
|
---|
| 1111 | LWIP_ASSERT("pcb->snd_queuelen >= pbuf_clen(next->p)", (pcb->snd_queuelen >= clen));
|
---|
| 1112 |
|
---|
| 1113 | pcb->snd_queuelen = (u16_t)(pcb->snd_queuelen - clen);
|
---|
| 1114 | recv_acked = (tcpwnd_size_t)(recv_acked + next->len);
|
---|
| 1115 | tcp_seg_free(next);
|
---|
| 1116 |
|
---|
| 1117 | LWIP_DEBUGF(TCP_QLEN_DEBUG, ("%"TCPWNDSIZE_F" (after freeing %s)\n",
|
---|
| 1118 | (tcpwnd_size_t)pcb->snd_queuelen,
|
---|
| 1119 | dbg_list_name));
|
---|
| 1120 | if (pcb->snd_queuelen != 0) {
|
---|
| 1121 | LWIP_ASSERT("tcp_receive: valid queue length",
|
---|
| 1122 | seg_list != NULL || dbg_other_seg_list != NULL);
|
---|
| 1123 | }
|
---|
| 1124 | }
|
---|
| 1125 | return seg_list;
|
---|
| 1126 | }
|
---|
| 1127 |
|
---|
| 1128 | /**
|
---|
| 1129 | * Called by tcp_process. Checks if the given segment is an ACK for outstanding
|
---|
| 1130 | * data, and if so frees the memory of the buffered data. Next, it places the
|
---|
| 1131 | * segment on any of the receive queues (pcb->recved or pcb->ooseq). If the segment
|
---|
| 1132 | * is buffered, the pbuf is referenced by pbuf_ref so that it will not be freed until
|
---|
| 1133 | * it has been removed from the buffer.
|
---|
| 1134 | *
|
---|
| 1135 | * If the incoming segment constitutes an ACK for a segment that was used for RTT
|
---|
| 1136 | * estimation, the RTT is estimated here as well.
|
---|
| 1137 | *
|
---|
| 1138 | * Called from tcp_process().
|
---|
| 1139 | */
|
---|
| 1140 | static void
|
---|
| 1141 | tcp_receive(struct tcp_pcb *pcb)
|
---|
| 1142 | {
|
---|
| 1143 | s16_t m;
|
---|
| 1144 | u32_t right_wnd_edge;
|
---|
| 1145 | int found_dupack = 0;
|
---|
| 1146 |
|
---|
| 1147 | LWIP_ASSERT("tcp_receive: invalid pcb", pcb != NULL);
|
---|
| 1148 | LWIP_ASSERT("tcp_receive: wrong state", pcb->state >= ESTABLISHED);
|
---|
| 1149 |
|
---|
| 1150 | if (flags & TCP_ACK) {
|
---|
| 1151 | right_wnd_edge = pcb->snd_wnd + pcb->snd_wl2;
|
---|
| 1152 |
|
---|
| 1153 | /* Update window. */
|
---|
| 1154 | if (TCP_SEQ_LT(pcb->snd_wl1, seqno) ||
|
---|
| 1155 | (pcb->snd_wl1 == seqno && TCP_SEQ_LT(pcb->snd_wl2, ackno)) ||
|
---|
| 1156 | (pcb->snd_wl2 == ackno && (u32_t)SND_WND_SCALE(pcb, tcphdr->wnd) > pcb->snd_wnd)) {
|
---|
| 1157 | pcb->snd_wnd = SND_WND_SCALE(pcb, tcphdr->wnd);
|
---|
| 1158 | /* keep track of the biggest window announced by the remote host to calculate
|
---|
| 1159 | the maximum segment size */
|
---|
| 1160 | if (pcb->snd_wnd_max < pcb->snd_wnd) {
|
---|
| 1161 | pcb->snd_wnd_max = pcb->snd_wnd;
|
---|
| 1162 | }
|
---|
| 1163 | pcb->snd_wl1 = seqno;
|
---|
| 1164 | pcb->snd_wl2 = ackno;
|
---|
| 1165 | LWIP_DEBUGF(TCP_WND_DEBUG, ("tcp_receive: window update %"TCPWNDSIZE_F"\n", pcb->snd_wnd));
|
---|
| 1166 | #if TCP_WND_DEBUG
|
---|
| 1167 | } else {
|
---|
| 1168 | if (pcb->snd_wnd != (tcpwnd_size_t)SND_WND_SCALE(pcb, tcphdr->wnd)) {
|
---|
| 1169 | LWIP_DEBUGF(TCP_WND_DEBUG,
|
---|
| 1170 | ("tcp_receive: no window update lastack %"U32_F" ackno %"
|
---|
| 1171 | U32_F" wl1 %"U32_F" seqno %"U32_F" wl2 %"U32_F"\n",
|
---|
| 1172 | pcb->lastack, ackno, pcb->snd_wl1, seqno, pcb->snd_wl2));
|
---|
| 1173 | }
|
---|
| 1174 | #endif /* TCP_WND_DEBUG */
|
---|
| 1175 | }
|
---|
| 1176 |
|
---|
| 1177 | /* (From Stevens TCP/IP Illustrated Vol II, p970.) Its only a
|
---|
| 1178 | * duplicate ack if:
|
---|
| 1179 | * 1) It doesn't ACK new data
|
---|
| 1180 | * 2) length of received packet is zero (i.e. no payload)
|
---|
| 1181 | * 3) the advertised window hasn't changed
|
---|
| 1182 | * 4) There is outstanding unacknowledged data (retransmission timer running)
|
---|
| 1183 | * 5) The ACK is == biggest ACK sequence number so far seen (snd_una)
|
---|
| 1184 | *
|
---|
| 1185 | * If it passes all five, should process as a dupack:
|
---|
| 1186 | * a) dupacks < 3: do nothing
|
---|
| 1187 | * b) dupacks == 3: fast retransmit
|
---|
| 1188 | * c) dupacks > 3: increase cwnd
|
---|
| 1189 | *
|
---|
| 1190 | * If it only passes 1-3, should reset dupack counter (and add to
|
---|
| 1191 | * stats, which we don't do in lwIP)
|
---|
| 1192 | *
|
---|
| 1193 | * If it only passes 1, should reset dupack counter
|
---|
| 1194 | *
|
---|
| 1195 | */
|
---|
| 1196 |
|
---|
| 1197 | /* Clause 1 */
|
---|
| 1198 | if (TCP_SEQ_LEQ(ackno, pcb->lastack)) {
|
---|
| 1199 | /* Clause 2 */
|
---|
| 1200 | if (tcplen == 0) {
|
---|
| 1201 | /* Clause 3 */
|
---|
| 1202 | if (pcb->snd_wl2 + pcb->snd_wnd == right_wnd_edge) {
|
---|
| 1203 | /* Clause 4 */
|
---|
| 1204 | if (pcb->rtime >= 0) {
|
---|
| 1205 | /* Clause 5 */
|
---|
| 1206 | if (pcb->lastack == ackno) {
|
---|
| 1207 | found_dupack = 1;
|
---|
| 1208 | if ((u8_t)(pcb->dupacks + 1) > pcb->dupacks) {
|
---|
| 1209 | ++pcb->dupacks;
|
---|
| 1210 | }
|
---|
| 1211 | if (pcb->dupacks > 3) {
|
---|
| 1212 | /* Inflate the congestion window */
|
---|
| 1213 | TCP_WND_INC(pcb->cwnd, pcb->mss);
|
---|
| 1214 | }
|
---|
| 1215 | if (pcb->dupacks >= 3) {
|
---|
| 1216 | /* Do fast retransmit (checked via TF_INFR, not via dupacks count) */
|
---|
| 1217 | tcp_rexmit_fast(pcb);
|
---|
| 1218 | }
|
---|
| 1219 | }
|
---|
| 1220 | }
|
---|
| 1221 | }
|
---|
| 1222 | }
|
---|
| 1223 | /* If Clause (1) or more is true, but not a duplicate ack, reset
|
---|
| 1224 | * count of consecutive duplicate acks */
|
---|
| 1225 | if (!found_dupack) {
|
---|
| 1226 | pcb->dupacks = 0;
|
---|
| 1227 | }
|
---|
| 1228 | } else if (TCP_SEQ_BETWEEN(ackno, pcb->lastack + 1, pcb->snd_nxt)) {
|
---|
| 1229 | /* We come here when the ACK acknowledges new data. */
|
---|
| 1230 | tcpwnd_size_t acked;
|
---|
| 1231 |
|
---|
| 1232 | /* Reset the "IN Fast Retransmit" flag, since we are no longer
|
---|
| 1233 | in fast retransmit. Also reset the congestion window to the
|
---|
| 1234 | slow start threshold. */
|
---|
| 1235 | if (pcb->flags & TF_INFR) {
|
---|
| 1236 | tcp_clear_flags(pcb, TF_INFR);
|
---|
| 1237 | pcb->cwnd = pcb->ssthresh;
|
---|
| 1238 | pcb->bytes_acked = 0;
|
---|
| 1239 | }
|
---|
| 1240 |
|
---|
| 1241 | /* Reset the number of retransmissions. */
|
---|
| 1242 | pcb->nrtx = 0;
|
---|
| 1243 |
|
---|
| 1244 | /* Reset the retransmission time-out. */
|
---|
| 1245 | pcb->rto = (s16_t)((pcb->sa >> 3) + pcb->sv);
|
---|
| 1246 |
|
---|
| 1247 | /* Record how much data this ACK acks */
|
---|
| 1248 | acked = (tcpwnd_size_t)(ackno - pcb->lastack);
|
---|
| 1249 |
|
---|
| 1250 | /* Reset the fast retransmit variables. */
|
---|
| 1251 | pcb->dupacks = 0;
|
---|
| 1252 | pcb->lastack = ackno;
|
---|
| 1253 |
|
---|
| 1254 | /* Update the congestion control variables (cwnd and
|
---|
| 1255 | ssthresh). */
|
---|
| 1256 | if (pcb->state >= ESTABLISHED) {
|
---|
| 1257 | if (pcb->cwnd < pcb->ssthresh) {
|
---|
| 1258 | tcpwnd_size_t increase;
|
---|
| 1259 | /* limit to 1 SMSS segment during period following RTO */
|
---|
| 1260 | u8_t num_seg = (pcb->flags & TF_RTO) ? 1 : 2;
|
---|
| 1261 | /* RFC 3465, section 2.2 Slow Start */
|
---|
| 1262 | increase = LWIP_MIN(acked, (tcpwnd_size_t)(num_seg * pcb->mss));
|
---|
| 1263 | TCP_WND_INC(pcb->cwnd, increase);
|
---|
| 1264 | LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_receive: slow start cwnd %"TCPWNDSIZE_F"\n", pcb->cwnd));
|
---|
| 1265 | } else {
|
---|
| 1266 | /* RFC 3465, section 2.1 Congestion Avoidance */
|
---|
| 1267 | TCP_WND_INC(pcb->bytes_acked, acked);
|
---|
| 1268 | if (pcb->bytes_acked >= pcb->cwnd) {
|
---|
| 1269 | pcb->bytes_acked = (tcpwnd_size_t)(pcb->bytes_acked - pcb->cwnd);
|
---|
| 1270 | TCP_WND_INC(pcb->cwnd, pcb->mss);
|
---|
| 1271 | }
|
---|
| 1272 | LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_receive: congestion avoidance cwnd %"TCPWNDSIZE_F"\n", pcb->cwnd));
|
---|
| 1273 | }
|
---|
| 1274 | }
|
---|
| 1275 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: ACK for %"U32_F", unacked->seqno %"U32_F":%"U32_F"\n",
|
---|
| 1276 | ackno,
|
---|
| 1277 | pcb->unacked != NULL ?
|
---|
| 1278 | lwip_ntohl(pcb->unacked->tcphdr->seqno) : 0,
|
---|
| 1279 | pcb->unacked != NULL ?
|
---|
| 1280 | lwip_ntohl(pcb->unacked->tcphdr->seqno) + TCP_TCPLEN(pcb->unacked) : 0));
|
---|
| 1281 |
|
---|
| 1282 | /* Remove segment from the unacknowledged list if the incoming
|
---|
| 1283 | ACK acknowledges them. */
|
---|
| 1284 | pcb->unacked = tcp_free_acked_segments(pcb, pcb->unacked, "unacked", pcb->unsent);
|
---|
| 1285 | /* We go through the ->unsent list to see if any of the segments
|
---|
| 1286 | on the list are acknowledged by the ACK. This may seem
|
---|
| 1287 | strange since an "unsent" segment shouldn't be acked. The
|
---|
| 1288 | rationale is that lwIP puts all outstanding segments on the
|
---|
| 1289 | ->unsent list after a retransmission, so these segments may
|
---|
| 1290 | in fact have been sent once. */
|
---|
| 1291 | pcb->unsent = tcp_free_acked_segments(pcb, pcb->unsent, "unsent", pcb->unacked);
|
---|
| 1292 |
|
---|
| 1293 | /* If there's nothing left to acknowledge, stop the retransmit
|
---|
| 1294 | timer, otherwise reset it to start again */
|
---|
| 1295 | if (pcb->unacked == NULL) {
|
---|
| 1296 | pcb->rtime = -1;
|
---|
| 1297 | } else {
|
---|
| 1298 | pcb->rtime = 0;
|
---|
| 1299 | }
|
---|
| 1300 |
|
---|
| 1301 | pcb->polltmr = 0;
|
---|
| 1302 |
|
---|
| 1303 | #if TCP_OVERSIZE
|
---|
| 1304 | if (pcb->unsent == NULL) {
|
---|
| 1305 | pcb->unsent_oversize = 0;
|
---|
| 1306 | }
|
---|
| 1307 | #endif /* TCP_OVERSIZE */
|
---|
| 1308 |
|
---|
| 1309 | #if LWIP_IPV6 && LWIP_ND6_TCP_REACHABILITY_HINTS
|
---|
| 1310 | if (ip_current_is_v6()) {
|
---|
| 1311 | /* Inform neighbor reachability of forward progress. */
|
---|
| 1312 | nd6_reachability_hint(ip6_current_src_addr());
|
---|
| 1313 | }
|
---|
| 1314 | #endif /* LWIP_IPV6 && LWIP_ND6_TCP_REACHABILITY_HINTS*/
|
---|
| 1315 |
|
---|
| 1316 | pcb->snd_buf = (tcpwnd_size_t)(pcb->snd_buf + recv_acked);
|
---|
| 1317 | /* check if this ACK ends our retransmission of in-flight data */
|
---|
| 1318 | if (pcb->flags & TF_RTO) {
|
---|
| 1319 | /* RTO is done if
|
---|
| 1320 | 1) both queues are empty or
|
---|
| 1321 | 2) unacked is empty and unsent head contains data not part of RTO or
|
---|
| 1322 | 3) unacked head contains data not part of RTO */
|
---|
| 1323 | if (pcb->unacked == NULL) {
|
---|
| 1324 | if ((pcb->unsent == NULL) ||
|
---|
| 1325 | (TCP_SEQ_LEQ(pcb->rto_end, lwip_ntohl(pcb->unsent->tcphdr->seqno)))) {
|
---|
| 1326 | tcp_clear_flags(pcb, TF_RTO);
|
---|
| 1327 | }
|
---|
| 1328 | } else if (TCP_SEQ_LEQ(pcb->rto_end, lwip_ntohl(pcb->unacked->tcphdr->seqno))) {
|
---|
| 1329 | tcp_clear_flags(pcb, TF_RTO);
|
---|
| 1330 | }
|
---|
| 1331 | }
|
---|
| 1332 | /* End of ACK for new data processing. */
|
---|
| 1333 | } else {
|
---|
| 1334 | /* Out of sequence ACK, didn't really ack anything */
|
---|
| 1335 | tcp_send_empty_ack(pcb);
|
---|
| 1336 | }
|
---|
| 1337 |
|
---|
| 1338 | LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: pcb->rttest %"U32_F" rtseq %"U32_F" ackno %"U32_F"\n",
|
---|
| 1339 | pcb->rttest, pcb->rtseq, ackno));
|
---|
| 1340 |
|
---|
| 1341 | /* RTT estimation calculations. This is done by checking if the
|
---|
| 1342 | incoming segment acknowledges the segment we use to take a
|
---|
| 1343 | round-trip time measurement. */
|
---|
| 1344 | if (pcb->rttest && TCP_SEQ_LT(pcb->rtseq, ackno)) {
|
---|
| 1345 | /* diff between this shouldn't exceed 32K since this are tcp timer ticks
|
---|
| 1346 | and a round-trip shouldn't be that long... */
|
---|
| 1347 | m = (s16_t)(tcp_ticks - pcb->rttest);
|
---|
| 1348 |
|
---|
| 1349 | LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: experienced rtt %"U16_F" ticks (%"U16_F" msec).\n",
|
---|
| 1350 | m, (u16_t)(m * TCP_SLOW_INTERVAL)));
|
---|
| 1351 |
|
---|
| 1352 | /* This is taken directly from VJs original code in his paper */
|
---|
| 1353 | m = (s16_t)(m - (pcb->sa >> 3));
|
---|
| 1354 | pcb->sa = (s16_t)(pcb->sa + m);
|
---|
| 1355 | if (m < 0) {
|
---|
| 1356 | m = (s16_t) - m;
|
---|
| 1357 | }
|
---|
| 1358 | m = (s16_t)(m - (pcb->sv >> 2));
|
---|
| 1359 | pcb->sv = (s16_t)(pcb->sv + m);
|
---|
| 1360 | pcb->rto = (s16_t)((pcb->sa >> 3) + pcb->sv);
|
---|
| 1361 |
|
---|
| 1362 | LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: RTO %"U16_F" (%"U16_F" milliseconds)\n",
|
---|
| 1363 | pcb->rto, (u16_t)(pcb->rto * TCP_SLOW_INTERVAL)));
|
---|
| 1364 |
|
---|
| 1365 | pcb->rttest = 0;
|
---|
| 1366 | }
|
---|
| 1367 | }
|
---|
| 1368 |
|
---|
| 1369 | /* If the incoming segment contains data, we must process it
|
---|
| 1370 | further unless the pcb already received a FIN.
|
---|
| 1371 | (RFC 793, chapter 3.9, "SEGMENT ARRIVES" in states CLOSE-WAIT, CLOSING,
|
---|
| 1372 | LAST-ACK and TIME-WAIT: "Ignore the segment text.") */
|
---|
| 1373 | if ((tcplen > 0) && (pcb->state < CLOSE_WAIT)) {
|
---|
| 1374 | /* This code basically does three things:
|
---|
| 1375 |
|
---|
| 1376 | +) If the incoming segment contains data that is the next
|
---|
| 1377 | in-sequence data, this data is passed to the application. This
|
---|
| 1378 | might involve trimming the first edge of the data. The rcv_nxt
|
---|
| 1379 | variable and the advertised window are adjusted.
|
---|
| 1380 |
|
---|
| 1381 | +) If the incoming segment has data that is above the next
|
---|
| 1382 | sequence number expected (->rcv_nxt), the segment is placed on
|
---|
| 1383 | the ->ooseq queue. This is done by finding the appropriate
|
---|
| 1384 | place in the ->ooseq queue (which is ordered by sequence
|
---|
| 1385 | number) and trim the segment in both ends if needed. An
|
---|
| 1386 | immediate ACK is sent to indicate that we received an
|
---|
| 1387 | out-of-sequence segment.
|
---|
| 1388 |
|
---|
| 1389 | +) Finally, we check if the first segment on the ->ooseq queue
|
---|
| 1390 | now is in sequence (i.e., if rcv_nxt >= ooseq->seqno). If
|
---|
| 1391 | rcv_nxt > ooseq->seqno, we must trim the first edge of the
|
---|
| 1392 | segment on ->ooseq before we adjust rcv_nxt. The data in the
|
---|
| 1393 | segments that are now on sequence are chained onto the
|
---|
| 1394 | incoming segment so that we only need to call the application
|
---|
| 1395 | once.
|
---|
| 1396 | */
|
---|
| 1397 |
|
---|
| 1398 | /* First, we check if we must trim the first edge. We have to do
|
---|
| 1399 | this if the sequence number of the incoming segment is less
|
---|
| 1400 | than rcv_nxt, and the sequence number plus the length of the
|
---|
| 1401 | segment is larger than rcv_nxt. */
|
---|
| 1402 | /* if (TCP_SEQ_LT(seqno, pcb->rcv_nxt)) {
|
---|
| 1403 | if (TCP_SEQ_LT(pcb->rcv_nxt, seqno + tcplen)) {*/
|
---|
| 1404 | if (TCP_SEQ_BETWEEN(pcb->rcv_nxt, seqno + 1, seqno + tcplen - 1)) {
|
---|
| 1405 | /* Trimming the first edge is done by pushing the payload
|
---|
| 1406 | pointer in the pbuf downwards. This is somewhat tricky since
|
---|
| 1407 | we do not want to discard the full contents of the pbuf up to
|
---|
| 1408 | the new starting point of the data since we have to keep the
|
---|
| 1409 | TCP header which is present in the first pbuf in the chain.
|
---|
| 1410 |
|
---|
| 1411 | What is done is really quite a nasty hack: the first pbuf in
|
---|
| 1412 | the pbuf chain is pointed to by inseg.p. Since we need to be
|
---|
| 1413 | able to deallocate the whole pbuf, we cannot change this
|
---|
| 1414 | inseg.p pointer to point to any of the later pbufs in the
|
---|
| 1415 | chain. Instead, we point the ->payload pointer in the first
|
---|
| 1416 | pbuf to data in one of the later pbufs. We also set the
|
---|
| 1417 | inseg.data pointer to point to the right place. This way, the
|
---|
| 1418 | ->p pointer will still point to the first pbuf, but the
|
---|
| 1419 | ->p->payload pointer will point to data in another pbuf.
|
---|
| 1420 |
|
---|
| 1421 | After we are done with adjusting the pbuf pointers we must
|
---|
| 1422 | adjust the ->data pointer in the seg and the segment
|
---|
| 1423 | length.*/
|
---|
| 1424 |
|
---|
| 1425 | struct pbuf *p = inseg.p;
|
---|
| 1426 | u32_t off32 = pcb->rcv_nxt - seqno;
|
---|
| 1427 | u16_t new_tot_len, off;
|
---|
| 1428 | LWIP_ASSERT("inseg.p != NULL", inseg.p);
|
---|
| 1429 | LWIP_ASSERT("insane offset!", (off32 < 0xffff));
|
---|
| 1430 | off = (u16_t)off32;
|
---|
| 1431 | LWIP_ASSERT("pbuf too short!", (((s32_t)inseg.p->tot_len) >= off));
|
---|
| 1432 | inseg.len -= off;
|
---|
| 1433 | new_tot_len = (u16_t)(inseg.p->tot_len - off);
|
---|
| 1434 | while (p->len < off) {
|
---|
| 1435 | off -= p->len;
|
---|
| 1436 | /* all pbufs up to and including this one have len==0, so tot_len is equal */
|
---|
| 1437 | p->tot_len = new_tot_len;
|
---|
| 1438 | p->len = 0;
|
---|
| 1439 | p = p->next;
|
---|
| 1440 | }
|
---|
| 1441 | /* cannot fail... */
|
---|
| 1442 | pbuf_remove_header(p, off);
|
---|
| 1443 | inseg.tcphdr->seqno = seqno = pcb->rcv_nxt;
|
---|
| 1444 | } else {
|
---|
| 1445 | if (TCP_SEQ_LT(seqno, pcb->rcv_nxt)) {
|
---|
| 1446 | /* the whole segment is < rcv_nxt */
|
---|
| 1447 | /* must be a duplicate of a packet that has already been correctly handled */
|
---|
| 1448 |
|
---|
| 1449 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: duplicate seqno %"U32_F"\n", seqno));
|
---|
| 1450 | tcp_ack_now(pcb);
|
---|
| 1451 | }
|
---|
| 1452 | }
|
---|
| 1453 |
|
---|
| 1454 | /* The sequence number must be within the window (above rcv_nxt
|
---|
| 1455 | and below rcv_nxt + rcv_wnd) in order to be further
|
---|
| 1456 | processed. */
|
---|
| 1457 | if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt,
|
---|
| 1458 | pcb->rcv_nxt + pcb->rcv_wnd - 1)) {
|
---|
| 1459 | if (pcb->rcv_nxt == seqno) {
|
---|
| 1460 | /* The incoming segment is the next in sequence. We check if
|
---|
| 1461 | we have to trim the end of the segment and update rcv_nxt
|
---|
| 1462 | and pass the data to the application. */
|
---|
| 1463 | tcplen = TCP_TCPLEN(&inseg);
|
---|
| 1464 |
|
---|
| 1465 | if (tcplen > pcb->rcv_wnd) {
|
---|
| 1466 | LWIP_DEBUGF(TCP_INPUT_DEBUG,
|
---|
| 1467 | ("tcp_receive: other end overran receive window"
|
---|
| 1468 | "seqno %"U32_F" len %"U16_F" right edge %"U32_F"\n",
|
---|
| 1469 | seqno, tcplen, pcb->rcv_nxt + pcb->rcv_wnd));
|
---|
| 1470 | if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
|
---|
| 1471 | /* Must remove the FIN from the header as we're trimming
|
---|
| 1472 | * that byte of sequence-space from the packet */
|
---|
| 1473 | TCPH_FLAGS_SET(inseg.tcphdr, TCPH_FLAGS(inseg.tcphdr) & ~(unsigned int)TCP_FIN);
|
---|
| 1474 | }
|
---|
| 1475 | /* Adjust length of segment to fit in the window. */
|
---|
| 1476 | TCPWND_CHECK16(pcb->rcv_wnd);
|
---|
| 1477 | inseg.len = (u16_t)pcb->rcv_wnd;
|
---|
| 1478 | if (TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) {
|
---|
| 1479 | inseg.len -= 1;
|
---|
| 1480 | }
|
---|
| 1481 | pbuf_realloc(inseg.p, inseg.len);
|
---|
| 1482 | tcplen = TCP_TCPLEN(&inseg);
|
---|
| 1483 | LWIP_ASSERT("tcp_receive: segment not trimmed correctly to rcv_wnd\n",
|
---|
| 1484 | (seqno + tcplen) == (pcb->rcv_nxt + pcb->rcv_wnd));
|
---|
| 1485 | }
|
---|
| 1486 | #if TCP_QUEUE_OOSEQ
|
---|
| 1487 | /* Received in-sequence data, adjust ooseq data if:
|
---|
| 1488 | - FIN has been received or
|
---|
| 1489 | - inseq overlaps with ooseq */
|
---|
| 1490 | if (pcb->ooseq != NULL) {
|
---|
| 1491 | if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
|
---|
| 1492 | LWIP_DEBUGF(TCP_INPUT_DEBUG,
|
---|
| 1493 | ("tcp_receive: received in-order FIN, binning ooseq queue\n"));
|
---|
| 1494 | /* Received in-order FIN means anything that was received
|
---|
| 1495 | * out of order must now have been received in-order, so
|
---|
| 1496 | * bin the ooseq queue */
|
---|
| 1497 | while (pcb->ooseq != NULL) {
|
---|
| 1498 | struct tcp_seg *old_ooseq = pcb->ooseq;
|
---|
| 1499 | pcb->ooseq = pcb->ooseq->next;
|
---|
| 1500 | tcp_seg_free(old_ooseq);
|
---|
| 1501 | }
|
---|
| 1502 | } else {
|
---|
| 1503 | struct tcp_seg *next = pcb->ooseq;
|
---|
| 1504 | /* Remove all segments on ooseq that are covered by inseg already.
|
---|
| 1505 | * FIN is copied from ooseq to inseg if present. */
|
---|
| 1506 | while (next &&
|
---|
| 1507 | TCP_SEQ_GEQ(seqno + tcplen,
|
---|
| 1508 | next->tcphdr->seqno + next->len)) {
|
---|
| 1509 | struct tcp_seg *tmp;
|
---|
| 1510 | /* inseg cannot have FIN here (already processed above) */
|
---|
| 1511 | if ((TCPH_FLAGS(next->tcphdr) & TCP_FIN) != 0 &&
|
---|
| 1512 | (TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) == 0) {
|
---|
| 1513 | TCPH_SET_FLAG(inseg.tcphdr, TCP_FIN);
|
---|
| 1514 | tcplen = TCP_TCPLEN(&inseg);
|
---|
| 1515 | }
|
---|
| 1516 | tmp = next;
|
---|
| 1517 | next = next->next;
|
---|
| 1518 | tcp_seg_free(tmp);
|
---|
| 1519 | }
|
---|
| 1520 | /* Now trim right side of inseg if it overlaps with the first
|
---|
| 1521 | * segment on ooseq */
|
---|
| 1522 | if (next &&
|
---|
| 1523 | TCP_SEQ_GT(seqno + tcplen,
|
---|
| 1524 | next->tcphdr->seqno)) {
|
---|
| 1525 | /* inseg cannot have FIN here (already processed above) */
|
---|
| 1526 | inseg.len = (u16_t)(next->tcphdr->seqno - seqno);
|
---|
| 1527 | if (TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) {
|
---|
| 1528 | inseg.len -= 1;
|
---|
| 1529 | }
|
---|
| 1530 | pbuf_realloc(inseg.p, inseg.len);
|
---|
| 1531 | tcplen = TCP_TCPLEN(&inseg);
|
---|
| 1532 | LWIP_ASSERT("tcp_receive: segment not trimmed correctly to ooseq queue\n",
|
---|
| 1533 | (seqno + tcplen) == next->tcphdr->seqno);
|
---|
| 1534 | }
|
---|
| 1535 | pcb->ooseq = next;
|
---|
| 1536 | }
|
---|
| 1537 | }
|
---|
| 1538 | #endif /* TCP_QUEUE_OOSEQ */
|
---|
| 1539 |
|
---|
| 1540 | pcb->rcv_nxt = seqno + tcplen;
|
---|
| 1541 |
|
---|
| 1542 | /* Update the receiver's (our) window. */
|
---|
| 1543 | LWIP_ASSERT("tcp_receive: tcplen > rcv_wnd\n", pcb->rcv_wnd >= tcplen);
|
---|
| 1544 | pcb->rcv_wnd -= tcplen;
|
---|
| 1545 |
|
---|
| 1546 | tcp_update_rcv_ann_wnd(pcb);
|
---|
| 1547 |
|
---|
| 1548 | /* If there is data in the segment, we make preparations to
|
---|
| 1549 | pass this up to the application. The ->recv_data variable
|
---|
| 1550 | is used for holding the pbuf that goes to the
|
---|
| 1551 | application. The code for reassembling out-of-sequence data
|
---|
| 1552 | chains its data on this pbuf as well.
|
---|
| 1553 |
|
---|
| 1554 | If the segment was a FIN, we set the TF_GOT_FIN flag that will
|
---|
| 1555 | be used to indicate to the application that the remote side has
|
---|
| 1556 | closed its end of the connection. */
|
---|
| 1557 | if (inseg.p->tot_len > 0) {
|
---|
| 1558 | recv_data = inseg.p;
|
---|
| 1559 | /* Since this pbuf now is the responsibility of the
|
---|
| 1560 | application, we delete our reference to it so that we won't
|
---|
| 1561 | (mistakingly) deallocate it. */
|
---|
| 1562 | inseg.p = NULL;
|
---|
| 1563 | }
|
---|
| 1564 | if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
|
---|
| 1565 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: received FIN.\n"));
|
---|
| 1566 | recv_flags |= TF_GOT_FIN;
|
---|
| 1567 | }
|
---|
| 1568 |
|
---|
| 1569 | #if TCP_QUEUE_OOSEQ
|
---|
| 1570 | /* We now check if we have segments on the ->ooseq queue that
|
---|
| 1571 | are now in sequence. */
|
---|
| 1572 | while (pcb->ooseq != NULL &&
|
---|
| 1573 | pcb->ooseq->tcphdr->seqno == pcb->rcv_nxt) {
|
---|
| 1574 |
|
---|
| 1575 | struct tcp_seg *cseg = pcb->ooseq;
|
---|
| 1576 | seqno = pcb->ooseq->tcphdr->seqno;
|
---|
| 1577 |
|
---|
| 1578 | pcb->rcv_nxt += TCP_TCPLEN(cseg);
|
---|
| 1579 | LWIP_ASSERT("tcp_receive: ooseq tcplen > rcv_wnd\n",
|
---|
| 1580 | pcb->rcv_wnd >= TCP_TCPLEN(cseg));
|
---|
| 1581 | pcb->rcv_wnd -= TCP_TCPLEN(cseg);
|
---|
| 1582 |
|
---|
| 1583 | tcp_update_rcv_ann_wnd(pcb);
|
---|
| 1584 |
|
---|
| 1585 | if (cseg->p->tot_len > 0) {
|
---|
| 1586 | /* Chain this pbuf onto the pbuf that we will pass to
|
---|
| 1587 | the application. */
|
---|
| 1588 | /* With window scaling, this can overflow recv_data->tot_len, but
|
---|
| 1589 | that's not a problem since we explicitly fix that before passing
|
---|
| 1590 | recv_data to the application. */
|
---|
| 1591 | if (recv_data) {
|
---|
| 1592 | pbuf_cat(recv_data, cseg->p);
|
---|
| 1593 | } else {
|
---|
| 1594 | recv_data = cseg->p;
|
---|
| 1595 | }
|
---|
| 1596 | cseg->p = NULL;
|
---|
| 1597 | }
|
---|
| 1598 | if (TCPH_FLAGS(cseg->tcphdr) & TCP_FIN) {
|
---|
| 1599 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: dequeued FIN.\n"));
|
---|
| 1600 | recv_flags |= TF_GOT_FIN;
|
---|
| 1601 | if (pcb->state == ESTABLISHED) { /* force passive close or we can move to active close */
|
---|
| 1602 | pcb->state = CLOSE_WAIT;
|
---|
| 1603 | }
|
---|
| 1604 | }
|
---|
| 1605 |
|
---|
| 1606 | pcb->ooseq = cseg->next;
|
---|
| 1607 | tcp_seg_free(cseg);
|
---|
| 1608 | }
|
---|
| 1609 | #if LWIP_TCP_SACK_OUT
|
---|
| 1610 | if (pcb->flags & TF_SACK) {
|
---|
| 1611 | if (pcb->ooseq != NULL) {
|
---|
| 1612 | /* Some segments may have been removed from ooseq, let's remove all SACKs that
|
---|
| 1613 | describe anything before the new beginning of that list. */
|
---|
| 1614 | tcp_remove_sacks_lt(pcb, pcb->ooseq->tcphdr->seqno);
|
---|
| 1615 | } else if (LWIP_TCP_SACK_VALID(pcb, 0)) {
|
---|
| 1616 | /* ooseq has been cleared. Nothing to SACK */
|
---|
| 1617 | memset(pcb->rcv_sacks, 0, sizeof(pcb->rcv_sacks));
|
---|
| 1618 | }
|
---|
| 1619 | }
|
---|
| 1620 | #endif /* LWIP_TCP_SACK_OUT */
|
---|
| 1621 | #endif /* TCP_QUEUE_OOSEQ */
|
---|
| 1622 |
|
---|
| 1623 |
|
---|
| 1624 | /* Acknowledge the segment(s). */
|
---|
| 1625 | tcp_ack(pcb);
|
---|
| 1626 |
|
---|
| 1627 | #if LWIP_TCP_SACK_OUT
|
---|
| 1628 | if (LWIP_TCP_SACK_VALID(pcb, 0)) {
|
---|
| 1629 | /* Normally the ACK for the data received could be piggy-backed on a data packet,
|
---|
| 1630 | but lwIP currently does not support including SACKs in data packets. So we force
|
---|
| 1631 | it to respond with an empty ACK packet (only if there is at least one SACK to be sent).
|
---|
| 1632 | NOTE: tcp_send_empty_ack() on success clears the ACK flags (set by tcp_ack()) */
|
---|
| 1633 | tcp_send_empty_ack(pcb);
|
---|
| 1634 | }
|
---|
| 1635 | #endif /* LWIP_TCP_SACK_OUT */
|
---|
| 1636 |
|
---|
| 1637 | #if LWIP_IPV6 && LWIP_ND6_TCP_REACHABILITY_HINTS
|
---|
| 1638 | if (ip_current_is_v6()) {
|
---|
| 1639 | /* Inform neighbor reachability of forward progress. */
|
---|
| 1640 | nd6_reachability_hint(ip6_current_src_addr());
|
---|
| 1641 | }
|
---|
| 1642 | #endif /* LWIP_IPV6 && LWIP_ND6_TCP_REACHABILITY_HINTS*/
|
---|
| 1643 |
|
---|
| 1644 | } else {
|
---|
| 1645 | /* We get here if the incoming segment is out-of-sequence. */
|
---|
| 1646 |
|
---|
| 1647 | #if TCP_QUEUE_OOSEQ
|
---|
| 1648 | /* We queue the segment on the ->ooseq queue. */
|
---|
| 1649 | if (pcb->ooseq == NULL) {
|
---|
| 1650 | pcb->ooseq = tcp_seg_copy(&inseg);
|
---|
| 1651 | #if LWIP_TCP_SACK_OUT
|
---|
| 1652 | if (pcb->flags & TF_SACK) {
|
---|
| 1653 | /* All the SACKs should be invalid, so we can simply store the most recent one: */
|
---|
| 1654 | pcb->rcv_sacks[0].left = seqno;
|
---|
| 1655 | pcb->rcv_sacks[0].right = seqno + inseg.len;
|
---|
| 1656 | }
|
---|
| 1657 | #endif /* LWIP_TCP_SACK_OUT */
|
---|
| 1658 | } else {
|
---|
| 1659 | /* If the queue is not empty, we walk through the queue and
|
---|
| 1660 | try to find a place where the sequence number of the
|
---|
| 1661 | incoming segment is between the sequence numbers of the
|
---|
| 1662 | previous and the next segment on the ->ooseq queue. That is
|
---|
| 1663 | the place where we put the incoming segment. If needed, we
|
---|
| 1664 | trim the second edges of the previous and the incoming
|
---|
| 1665 | segment so that it will fit into the sequence.
|
---|
| 1666 |
|
---|
| 1667 | If the incoming segment has the same sequence number as a
|
---|
| 1668 | segment on the ->ooseq queue, we discard the segment that
|
---|
| 1669 | contains less data. */
|
---|
| 1670 |
|
---|
| 1671 | #if LWIP_TCP_SACK_OUT
|
---|
| 1672 | /* This is the left edge of the lowest possible SACK range.
|
---|
| 1673 | It may start before the newly received segment (possibly adjusted below). */
|
---|
| 1674 | u32_t sackbeg = TCP_SEQ_LT(seqno, pcb->ooseq->tcphdr->seqno) ? seqno : pcb->ooseq->tcphdr->seqno;
|
---|
| 1675 | #endif /* LWIP_TCP_SACK_OUT */
|
---|
| 1676 | struct tcp_seg *next, *prev = NULL;
|
---|
| 1677 | for (next = pcb->ooseq; next != NULL; next = next->next) {
|
---|
| 1678 | if (seqno == next->tcphdr->seqno) {
|
---|
| 1679 | /* The sequence number of the incoming segment is the
|
---|
| 1680 | same as the sequence number of the segment on
|
---|
| 1681 | ->ooseq. We check the lengths to see which one to
|
---|
| 1682 | discard. */
|
---|
| 1683 | if (inseg.len > next->len) {
|
---|
| 1684 | /* The incoming segment is larger than the old
|
---|
| 1685 | segment. We replace some segments with the new
|
---|
| 1686 | one. */
|
---|
| 1687 | struct tcp_seg *cseg = tcp_seg_copy(&inseg);
|
---|
| 1688 | if (cseg != NULL) {
|
---|
| 1689 | if (prev != NULL) {
|
---|
| 1690 | prev->next = cseg;
|
---|
| 1691 | } else {
|
---|
| 1692 | pcb->ooseq = cseg;
|
---|
| 1693 | }
|
---|
| 1694 | tcp_oos_insert_segment(cseg, next);
|
---|
| 1695 | }
|
---|
| 1696 | break;
|
---|
| 1697 | } else {
|
---|
| 1698 | /* Either the lengths are the same or the incoming
|
---|
| 1699 | segment was smaller than the old one; in either
|
---|
| 1700 | case, we ditch the incoming segment. */
|
---|
| 1701 | break;
|
---|
| 1702 | }
|
---|
| 1703 | } else {
|
---|
| 1704 | if (prev == NULL) {
|
---|
| 1705 | if (TCP_SEQ_LT(seqno, next->tcphdr->seqno)) {
|
---|
| 1706 | /* The sequence number of the incoming segment is lower
|
---|
| 1707 | than the sequence number of the first segment on the
|
---|
| 1708 | queue. We put the incoming segment first on the
|
---|
| 1709 | queue. */
|
---|
| 1710 | struct tcp_seg *cseg = tcp_seg_copy(&inseg);
|
---|
| 1711 | if (cseg != NULL) {
|
---|
| 1712 | pcb->ooseq = cseg;
|
---|
| 1713 | tcp_oos_insert_segment(cseg, next);
|
---|
| 1714 | }
|
---|
| 1715 | break;
|
---|
| 1716 | }
|
---|
| 1717 | } else {
|
---|
| 1718 | /*if (TCP_SEQ_LT(prev->tcphdr->seqno, seqno) &&
|
---|
| 1719 | TCP_SEQ_LT(seqno, next->tcphdr->seqno)) {*/
|
---|
| 1720 | if (TCP_SEQ_BETWEEN(seqno, prev->tcphdr->seqno + 1, next->tcphdr->seqno - 1)) {
|
---|
| 1721 | /* The sequence number of the incoming segment is in
|
---|
| 1722 | between the sequence numbers of the previous and
|
---|
| 1723 | the next segment on ->ooseq. We trim trim the previous
|
---|
| 1724 | segment, delete next segments that included in received segment
|
---|
| 1725 | and trim received, if needed. */
|
---|
| 1726 | struct tcp_seg *cseg = tcp_seg_copy(&inseg);
|
---|
| 1727 | if (cseg != NULL) {
|
---|
| 1728 | if (TCP_SEQ_GT(prev->tcphdr->seqno + prev->len, seqno)) {
|
---|
| 1729 | /* We need to trim the prev segment. */
|
---|
| 1730 | prev->len = (u16_t)(seqno - prev->tcphdr->seqno);
|
---|
| 1731 | pbuf_realloc(prev->p, prev->len);
|
---|
| 1732 | }
|
---|
| 1733 | prev->next = cseg;
|
---|
| 1734 | tcp_oos_insert_segment(cseg, next);
|
---|
| 1735 | }
|
---|
| 1736 | break;
|
---|
| 1737 | }
|
---|
| 1738 | }
|
---|
| 1739 |
|
---|
| 1740 | #if LWIP_TCP_SACK_OUT
|
---|
| 1741 | /* The new segment goes after the 'next' one. If there is a "hole" in sequence numbers
|
---|
| 1742 | between 'prev' and the beginning of 'next', we want to move sackbeg. */
|
---|
| 1743 | if (prev != NULL && prev->tcphdr->seqno + prev->len != next->tcphdr->seqno) {
|
---|
| 1744 | sackbeg = next->tcphdr->seqno;
|
---|
| 1745 | }
|
---|
| 1746 | #endif /* LWIP_TCP_SACK_OUT */
|
---|
| 1747 |
|
---|
| 1748 | /* We don't use 'prev' below, so let's set it to current 'next'.
|
---|
| 1749 | This way even if we break the loop below, 'prev' will be pointing
|
---|
| 1750 | at the segment right in front of the newly added one. */
|
---|
| 1751 | prev = next;
|
---|
| 1752 |
|
---|
| 1753 | /* If the "next" segment is the last segment on the
|
---|
| 1754 | ooseq queue, we add the incoming segment to the end
|
---|
| 1755 | of the list. */
|
---|
| 1756 | if (next->next == NULL &&
|
---|
| 1757 | TCP_SEQ_GT(seqno, next->tcphdr->seqno)) {
|
---|
| 1758 | if (TCPH_FLAGS(next->tcphdr) & TCP_FIN) {
|
---|
| 1759 | /* segment "next" already contains all data */
|
---|
| 1760 | break;
|
---|
| 1761 | }
|
---|
| 1762 | next->next = tcp_seg_copy(&inseg);
|
---|
| 1763 | if (next->next != NULL) {
|
---|
| 1764 | if (TCP_SEQ_GT(next->tcphdr->seqno + next->len, seqno)) {
|
---|
| 1765 | /* We need to trim the last segment. */
|
---|
| 1766 | next->len = (u16_t)(seqno - next->tcphdr->seqno);
|
---|
| 1767 | pbuf_realloc(next->p, next->len);
|
---|
| 1768 | }
|
---|
| 1769 | /* check if the remote side overruns our receive window */
|
---|
| 1770 | if (TCP_SEQ_GT((u32_t)tcplen + seqno, pcb->rcv_nxt + (u32_t)pcb->rcv_wnd)) {
|
---|
| 1771 | LWIP_DEBUGF(TCP_INPUT_DEBUG,
|
---|
| 1772 | ("tcp_receive: other end overran receive window"
|
---|
| 1773 | "seqno %"U32_F" len %"U16_F" right edge %"U32_F"\n",
|
---|
| 1774 | seqno, tcplen, pcb->rcv_nxt + pcb->rcv_wnd));
|
---|
| 1775 | if (TCPH_FLAGS(next->next->tcphdr) & TCP_FIN) {
|
---|
| 1776 | /* Must remove the FIN from the header as we're trimming
|
---|
| 1777 | * that byte of sequence-space from the packet */
|
---|
| 1778 | TCPH_FLAGS_SET(next->next->tcphdr, TCPH_FLAGS(next->next->tcphdr) & ~TCP_FIN);
|
---|
| 1779 | }
|
---|
| 1780 | /* Adjust length of segment to fit in the window. */
|
---|
| 1781 | next->next->len = (u16_t)(pcb->rcv_nxt + pcb->rcv_wnd - seqno);
|
---|
| 1782 | pbuf_realloc(next->next->p, next->next->len);
|
---|
| 1783 | tcplen = TCP_TCPLEN(next->next);
|
---|
| 1784 | LWIP_ASSERT("tcp_receive: segment not trimmed correctly to rcv_wnd\n",
|
---|
| 1785 | (seqno + tcplen) == (pcb->rcv_nxt + pcb->rcv_wnd));
|
---|
| 1786 | }
|
---|
| 1787 | }
|
---|
| 1788 | break;
|
---|
| 1789 | }
|
---|
| 1790 | }
|
---|
| 1791 | }
|
---|
| 1792 |
|
---|
| 1793 | #if LWIP_TCP_SACK_OUT
|
---|
| 1794 | if (pcb->flags & TF_SACK) {
|
---|
| 1795 | if (prev == NULL) {
|
---|
| 1796 | /* The new segment is at the beginning. sackbeg should already be set properly.
|
---|
| 1797 | We need to find the right edge. */
|
---|
| 1798 | next = pcb->ooseq;
|
---|
| 1799 | } else if (prev->next != NULL) {
|
---|
| 1800 | /* The new segment was added after 'prev'. If there is a "hole" between 'prev' and 'prev->next',
|
---|
| 1801 | we need to move sackbeg. After that we should find the right edge. */
|
---|
| 1802 | next = prev->next;
|
---|
| 1803 | if (prev->tcphdr->seqno + prev->len != next->tcphdr->seqno) {
|
---|
| 1804 | sackbeg = next->tcphdr->seqno;
|
---|
| 1805 | }
|
---|
| 1806 | } else {
|
---|
| 1807 | next = NULL;
|
---|
| 1808 | }
|
---|
| 1809 | if (next != NULL) {
|
---|
| 1810 | u32_t sackend = next->tcphdr->seqno;
|
---|
| 1811 | for ( ; (next != NULL) && (sackend == next->tcphdr->seqno); next = next->next) {
|
---|
| 1812 | sackend += next->len;
|
---|
| 1813 | }
|
---|
| 1814 | tcp_add_sack(pcb, sackbeg, sackend);
|
---|
| 1815 | }
|
---|
| 1816 | }
|
---|
| 1817 | #endif /* LWIP_TCP_SACK_OUT */
|
---|
| 1818 | }
|
---|
| 1819 | #if defined(TCP_OOSEQ_BYTES_LIMIT) || defined(TCP_OOSEQ_PBUFS_LIMIT)
|
---|
| 1820 | {
|
---|
| 1821 | /* Check that the data on ooseq doesn't exceed one of the limits
|
---|
| 1822 | and throw away everything above that limit. */
|
---|
| 1823 | #ifdef TCP_OOSEQ_BYTES_LIMIT
|
---|
| 1824 | const u32_t ooseq_max_blen = TCP_OOSEQ_BYTES_LIMIT(pcb);
|
---|
| 1825 | u32_t ooseq_blen = 0;
|
---|
| 1826 | #endif
|
---|
| 1827 | #ifdef TCP_OOSEQ_PBUFS_LIMIT
|
---|
| 1828 | const u16_t ooseq_max_qlen = TCP_OOSEQ_PBUFS_LIMIT(pcb);
|
---|
| 1829 | u16_t ooseq_qlen = 0;
|
---|
| 1830 | #endif
|
---|
| 1831 | struct tcp_seg *next, *prev = NULL;
|
---|
| 1832 | for (next = pcb->ooseq; next != NULL; prev = next, next = next->next) {
|
---|
| 1833 | struct pbuf *p = next->p;
|
---|
| 1834 | int stop_here = 0;
|
---|
| 1835 | #ifdef TCP_OOSEQ_BYTES_LIMIT
|
---|
| 1836 | ooseq_blen += p->tot_len;
|
---|
| 1837 | if (ooseq_blen > ooseq_max_blen) {
|
---|
| 1838 | stop_here = 1;
|
---|
| 1839 | }
|
---|
| 1840 | #endif
|
---|
| 1841 | #ifdef TCP_OOSEQ_PBUFS_LIMIT
|
---|
| 1842 | ooseq_qlen += pbuf_clen(p);
|
---|
| 1843 | if (ooseq_qlen > ooseq_max_qlen) {
|
---|
| 1844 | stop_here = 1;
|
---|
| 1845 | }
|
---|
| 1846 | #endif
|
---|
| 1847 | if (stop_here) {
|
---|
| 1848 | #if LWIP_TCP_SACK_OUT
|
---|
| 1849 | if (pcb->flags & TF_SACK) {
|
---|
| 1850 | /* Let's remove all SACKs from next's seqno up. */
|
---|
| 1851 | tcp_remove_sacks_gt(pcb, next->tcphdr->seqno);
|
---|
| 1852 | }
|
---|
| 1853 | #endif /* LWIP_TCP_SACK_OUT */
|
---|
| 1854 | /* too much ooseq data, dump this and everything after it */
|
---|
| 1855 | tcp_segs_free(next);
|
---|
| 1856 | if (prev == NULL) {
|
---|
| 1857 | /* first ooseq segment is too much, dump the whole queue */
|
---|
| 1858 | pcb->ooseq = NULL;
|
---|
| 1859 | } else {
|
---|
| 1860 | /* just dump 'next' and everything after it */
|
---|
| 1861 | prev->next = NULL;
|
---|
| 1862 | }
|
---|
| 1863 | break;
|
---|
| 1864 | }
|
---|
| 1865 | }
|
---|
| 1866 | }
|
---|
| 1867 | #endif /* TCP_OOSEQ_BYTES_LIMIT || TCP_OOSEQ_PBUFS_LIMIT */
|
---|
| 1868 | #endif /* TCP_QUEUE_OOSEQ */
|
---|
| 1869 |
|
---|
| 1870 | /* We send the ACK packet after we've (potentially) dealt with SACKs,
|
---|
| 1871 | so they can be included in the acknowledgment. */
|
---|
| 1872 | tcp_send_empty_ack(pcb);
|
---|
| 1873 | }
|
---|
| 1874 | } else {
|
---|
| 1875 | /* The incoming segment is not within the window. */
|
---|
| 1876 | tcp_send_empty_ack(pcb);
|
---|
| 1877 | }
|
---|
| 1878 | } else {
|
---|
| 1879 | /* Segments with length 0 is taken care of here. Segments that
|
---|
| 1880 | fall out of the window are ACKed. */
|
---|
| 1881 | if (!TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt, pcb->rcv_nxt + pcb->rcv_wnd - 1)) {
|
---|
| 1882 | tcp_ack_now(pcb);
|
---|
| 1883 | }
|
---|
| 1884 | }
|
---|
| 1885 | }
|
---|
| 1886 |
|
---|
| 1887 | static u8_t
|
---|
| 1888 | tcp_get_next_optbyte(void)
|
---|
| 1889 | {
|
---|
| 1890 | u16_t optidx = tcp_optidx++;
|
---|
| 1891 | if ((tcphdr_opt2 == NULL) || (optidx < tcphdr_opt1len)) {
|
---|
| 1892 | u8_t *opts = (u8_t *)tcphdr + TCP_HLEN;
|
---|
| 1893 | return opts[optidx];
|
---|
| 1894 | } else {
|
---|
| 1895 | u8_t idx = (u8_t)(optidx - tcphdr_opt1len);
|
---|
| 1896 | return tcphdr_opt2[idx];
|
---|
| 1897 | }
|
---|
| 1898 | }
|
---|
| 1899 |
|
---|
| 1900 | /**
|
---|
| 1901 | * Parses the options contained in the incoming segment.
|
---|
| 1902 | *
|
---|
| 1903 | * Called from tcp_listen_input() and tcp_process().
|
---|
| 1904 | * Currently, only the MSS option is supported!
|
---|
| 1905 | *
|
---|
| 1906 | * @param pcb the tcp_pcb for which a segment arrived
|
---|
| 1907 | */
|
---|
| 1908 | static void
|
---|
| 1909 | tcp_parseopt(struct tcp_pcb *pcb)
|
---|
| 1910 | {
|
---|
| 1911 | u8_t data;
|
---|
| 1912 | u16_t mss;
|
---|
| 1913 | #if LWIP_TCP_TIMESTAMPS
|
---|
| 1914 | u32_t tsval;
|
---|
| 1915 | #endif
|
---|
| 1916 |
|
---|
| 1917 | LWIP_ASSERT("tcp_parseopt: invalid pcb", pcb != NULL);
|
---|
| 1918 |
|
---|
| 1919 | /* Parse the TCP MSS option, if present. */
|
---|
| 1920 | if (tcphdr_optlen != 0) {
|
---|
| 1921 | for (tcp_optidx = 0; tcp_optidx < tcphdr_optlen; ) {
|
---|
| 1922 | u8_t opt = tcp_get_next_optbyte();
|
---|
| 1923 | switch (opt) {
|
---|
| 1924 | case LWIP_TCP_OPT_EOL:
|
---|
| 1925 | /* End of options. */
|
---|
| 1926 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: EOL\n"));
|
---|
| 1927 | return;
|
---|
| 1928 | case LWIP_TCP_OPT_NOP:
|
---|
| 1929 | /* NOP option. */
|
---|
| 1930 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: NOP\n"));
|
---|
| 1931 | break;
|
---|
| 1932 | case LWIP_TCP_OPT_MSS:
|
---|
| 1933 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: MSS\n"));
|
---|
| 1934 | if (tcp_get_next_optbyte() != LWIP_TCP_OPT_LEN_MSS || (tcp_optidx - 2 + LWIP_TCP_OPT_LEN_MSS) > tcphdr_optlen) {
|
---|
| 1935 | /* Bad length */
|
---|
| 1936 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
|
---|
| 1937 | return;
|
---|
| 1938 | }
|
---|
| 1939 | /* An MSS option with the right option length. */
|
---|
| 1940 | mss = (u16_t)(tcp_get_next_optbyte() << 8);
|
---|
| 1941 | mss |= tcp_get_next_optbyte();
|
---|
| 1942 | /* Limit the mss to the configured TCP_MSS and prevent division by zero */
|
---|
| 1943 | pcb->mss = ((mss > TCP_MSS) || (mss == 0)) ? TCP_MSS : mss;
|
---|
| 1944 | break;
|
---|
| 1945 | #if LWIP_WND_SCALE
|
---|
| 1946 | case LWIP_TCP_OPT_WS:
|
---|
| 1947 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: WND_SCALE\n"));
|
---|
| 1948 | if (tcp_get_next_optbyte() != LWIP_TCP_OPT_LEN_WS || (tcp_optidx - 2 + LWIP_TCP_OPT_LEN_WS) > tcphdr_optlen) {
|
---|
| 1949 | /* Bad length */
|
---|
| 1950 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
|
---|
| 1951 | return;
|
---|
| 1952 | }
|
---|
| 1953 | /* An WND_SCALE option with the right option length. */
|
---|
| 1954 | data = tcp_get_next_optbyte();
|
---|
| 1955 | /* If syn was received with wnd scale option,
|
---|
| 1956 | activate wnd scale opt, but only if this is not a retransmission */
|
---|
| 1957 | if ((flags & TCP_SYN) && !(pcb->flags & TF_WND_SCALE)) {
|
---|
| 1958 | pcb->snd_scale = data;
|
---|
| 1959 | if (pcb->snd_scale > 14U) {
|
---|
| 1960 | pcb->snd_scale = 14U;
|
---|
| 1961 | }
|
---|
| 1962 | pcb->rcv_scale = TCP_RCV_SCALE;
|
---|
| 1963 | tcp_set_flags(pcb, TF_WND_SCALE);
|
---|
| 1964 | /* window scaling is enabled, we can use the full receive window */
|
---|
| 1965 | LWIP_ASSERT("window not at default value", pcb->rcv_wnd == TCPWND_MIN16(TCP_WND));
|
---|
| 1966 | LWIP_ASSERT("window not at default value", pcb->rcv_ann_wnd == TCPWND_MIN16(TCP_WND));
|
---|
| 1967 | pcb->rcv_wnd = pcb->rcv_ann_wnd = TCP_WND;
|
---|
| 1968 | }
|
---|
| 1969 | break;
|
---|
| 1970 | #endif /* LWIP_WND_SCALE */
|
---|
| 1971 | #if LWIP_TCP_TIMESTAMPS
|
---|
| 1972 | case LWIP_TCP_OPT_TS:
|
---|
| 1973 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: TS\n"));
|
---|
| 1974 | if (tcp_get_next_optbyte() != LWIP_TCP_OPT_LEN_TS || (tcp_optidx - 2 + LWIP_TCP_OPT_LEN_TS) > tcphdr_optlen) {
|
---|
| 1975 | /* Bad length */
|
---|
| 1976 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
|
---|
| 1977 | return;
|
---|
| 1978 | }
|
---|
| 1979 | /* TCP timestamp option with valid length */
|
---|
| 1980 | tsval = tcp_get_next_optbyte();
|
---|
| 1981 | tsval |= (tcp_get_next_optbyte() << 8);
|
---|
| 1982 | tsval |= (tcp_get_next_optbyte() << 16);
|
---|
| 1983 | tsval |= (tcp_get_next_optbyte() << 24);
|
---|
| 1984 | if (flags & TCP_SYN) {
|
---|
| 1985 | pcb->ts_recent = lwip_ntohl(tsval);
|
---|
| 1986 | /* Enable sending timestamps in every segment now that we know
|
---|
| 1987 | the remote host supports it. */
|
---|
| 1988 | tcp_set_flags(pcb, TF_TIMESTAMP);
|
---|
| 1989 | } else if (TCP_SEQ_BETWEEN(pcb->ts_lastacksent, seqno, seqno + tcplen)) {
|
---|
| 1990 | pcb->ts_recent = lwip_ntohl(tsval);
|
---|
| 1991 | }
|
---|
| 1992 | /* Advance to next option (6 bytes already read) */
|
---|
| 1993 | tcp_optidx += LWIP_TCP_OPT_LEN_TS - 6;
|
---|
| 1994 | break;
|
---|
| 1995 | #endif /* LWIP_TCP_TIMESTAMPS */
|
---|
| 1996 | #if LWIP_TCP_SACK_OUT
|
---|
| 1997 | case LWIP_TCP_OPT_SACK_PERM:
|
---|
| 1998 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: SACK_PERM\n"));
|
---|
| 1999 | if (tcp_get_next_optbyte() != LWIP_TCP_OPT_LEN_SACK_PERM || (tcp_optidx - 2 + LWIP_TCP_OPT_LEN_SACK_PERM) > tcphdr_optlen) {
|
---|
| 2000 | /* Bad length */
|
---|
| 2001 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
|
---|
| 2002 | return;
|
---|
| 2003 | }
|
---|
| 2004 | /* TCP SACK_PERM option with valid length */
|
---|
| 2005 | if (flags & TCP_SYN) {
|
---|
| 2006 | /* We only set it if we receive it in a SYN (or SYN+ACK) packet */
|
---|
| 2007 | tcp_set_flags(pcb, TF_SACK);
|
---|
| 2008 | }
|
---|
| 2009 | break;
|
---|
| 2010 | #endif /* LWIP_TCP_SACK_OUT */
|
---|
| 2011 | default:
|
---|
| 2012 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: other\n"));
|
---|
| 2013 | data = tcp_get_next_optbyte();
|
---|
| 2014 | if (data < 2) {
|
---|
| 2015 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
|
---|
| 2016 | /* If the length field is zero, the options are malformed
|
---|
| 2017 | and we don't process them further. */
|
---|
| 2018 | return;
|
---|
| 2019 | }
|
---|
| 2020 | /* All other options have a length field, so that we easily
|
---|
| 2021 | can skip past them. */
|
---|
| 2022 | tcp_optidx += data - 2;
|
---|
| 2023 | }
|
---|
| 2024 | }
|
---|
| 2025 | }
|
---|
| 2026 | }
|
---|
| 2027 |
|
---|
| 2028 | void
|
---|
| 2029 | tcp_trigger_input_pcb_close(void)
|
---|
| 2030 | {
|
---|
| 2031 | recv_flags |= TF_CLOSED;
|
---|
| 2032 | }
|
---|
| 2033 |
|
---|
| 2034 | #if LWIP_TCP_SACK_OUT
|
---|
| 2035 | /**
|
---|
| 2036 | * Called by tcp_receive() to add new SACK entry.
|
---|
| 2037 | *
|
---|
| 2038 | * The new SACK entry will be placed at the beginning of rcv_sacks[], as the newest one.
|
---|
| 2039 | * Existing SACK entries will be "pushed back", to preserve their order.
|
---|
| 2040 | * This is the behavior described in RFC 2018, section 4.
|
---|
| 2041 | *
|
---|
| 2042 | * @param pcb the tcp_pcb for which a segment arrived
|
---|
| 2043 | * @param left the left side of the SACK (the first sequence number)
|
---|
| 2044 | * @param right the right side of the SACK (the first sequence number past this SACK)
|
---|
| 2045 | */
|
---|
| 2046 | static void
|
---|
| 2047 | tcp_add_sack(struct tcp_pcb *pcb, u32_t left, u32_t right)
|
---|
| 2048 | {
|
---|
| 2049 | u8_t i;
|
---|
| 2050 | u8_t unused_idx;
|
---|
| 2051 |
|
---|
| 2052 | if ((pcb->flags & TF_SACK) == 0 || !TCP_SEQ_LT(left, right)) {
|
---|
| 2053 | return;
|
---|
| 2054 | }
|
---|
| 2055 |
|
---|
| 2056 | /* First, let's remove all SACKs that are no longer needed (because they overlap with the newest one),
|
---|
| 2057 | while moving all other SACKs forward.
|
---|
| 2058 | We run this loop for all entries, until we find the first invalid one.
|
---|
| 2059 | There is no point checking after that. */
|
---|
| 2060 | for (i = unused_idx = 0; (i < LWIP_TCP_MAX_SACK_NUM) && LWIP_TCP_SACK_VALID(pcb, i); ++i) {
|
---|
| 2061 | /* We only want to use SACK at [i] if it doesn't overlap with left:right range.
|
---|
| 2062 | It does not overlap if its right side is before the newly added SACK,
|
---|
| 2063 | or if its left side is after the newly added SACK.
|
---|
| 2064 | NOTE: The equality should not really happen, but it doesn't hurt. */
|
---|
| 2065 | if (TCP_SEQ_LEQ(pcb->rcv_sacks[i].right, left) || TCP_SEQ_LEQ(right, pcb->rcv_sacks[i].left)) {
|
---|
| 2066 | if (unused_idx != i) {
|
---|
| 2067 | /* We don't need to copy if it's already in the right spot */
|
---|
| 2068 | pcb->rcv_sacks[unused_idx] = pcb->rcv_sacks[i];
|
---|
| 2069 | }
|
---|
| 2070 | ++unused_idx;
|
---|
| 2071 | }
|
---|
| 2072 | }
|
---|
| 2073 |
|
---|
| 2074 | /* Now 'unused_idx' is the index of the first invalid SACK entry,
|
---|
| 2075 | anywhere between 0 (no valid entries) and LWIP_TCP_MAX_SACK_NUM (all entries are valid).
|
---|
| 2076 | We want to clear this and all following SACKs.
|
---|
| 2077 | However, we will be adding another one in the front (and shifting everything else back).
|
---|
| 2078 | So let's just iterate from the back, and set each entry to the one to the left if it's valid,
|
---|
| 2079 | or to 0 if it is not. */
|
---|
| 2080 | for (i = LWIP_TCP_MAX_SACK_NUM - 1; i > 0; --i) {
|
---|
| 2081 | /* [i] is the index we are setting, and the value should be at index [i-1],
|
---|
| 2082 | or 0 if that index is unused (>= unused_idx). */
|
---|
| 2083 | if (i - 1 >= unused_idx) {
|
---|
| 2084 | /* [i-1] is unused. Let's clear [i]. */
|
---|
| 2085 | pcb->rcv_sacks[i].left = pcb->rcv_sacks[i].right = 0;
|
---|
| 2086 | } else {
|
---|
| 2087 | pcb->rcv_sacks[i] = pcb->rcv_sacks[i - 1];
|
---|
| 2088 | }
|
---|
| 2089 | }
|
---|
| 2090 |
|
---|
| 2091 | /* And now we can store the newest SACK */
|
---|
| 2092 | pcb->rcv_sacks[0].left = left;
|
---|
| 2093 | pcb->rcv_sacks[0].right = right;
|
---|
| 2094 | }
|
---|
| 2095 |
|
---|
| 2096 | /**
|
---|
| 2097 | * Called to remove a range of SACKs.
|
---|
| 2098 | *
|
---|
| 2099 | * SACK entries will be removed or adjusted to not acknowledge any sequence
|
---|
| 2100 | * numbers that are less than 'seq' passed. It not only invalidates entries,
|
---|
| 2101 | * but also moves all entries that are still valid to the beginning.
|
---|
| 2102 | *
|
---|
| 2103 | * @param pcb the tcp_pcb to modify
|
---|
| 2104 | * @param seq the lowest sequence number to keep in SACK entries
|
---|
| 2105 | */
|
---|
| 2106 | static void
|
---|
| 2107 | tcp_remove_sacks_lt(struct tcp_pcb *pcb, u32_t seq)
|
---|
| 2108 | {
|
---|
| 2109 | u8_t i;
|
---|
| 2110 | u8_t unused_idx;
|
---|
| 2111 |
|
---|
| 2112 | /* We run this loop for all entries, until we find the first invalid one.
|
---|
| 2113 | There is no point checking after that. */
|
---|
| 2114 | for (i = unused_idx = 0; (i < LWIP_TCP_MAX_SACK_NUM) && LWIP_TCP_SACK_VALID(pcb, i); ++i) {
|
---|
| 2115 | /* We only want to use SACK at index [i] if its right side is > 'seq'. */
|
---|
| 2116 | if (TCP_SEQ_GT(pcb->rcv_sacks[i].right, seq)) {
|
---|
| 2117 | if (unused_idx != i) {
|
---|
| 2118 | /* We only copy it if it's not in the right spot already. */
|
---|
| 2119 | pcb->rcv_sacks[unused_idx] = pcb->rcv_sacks[i];
|
---|
| 2120 | }
|
---|
| 2121 | /* NOTE: It is possible that its left side is < 'seq', in which case we should adjust it. */
|
---|
| 2122 | if (TCP_SEQ_LT(pcb->rcv_sacks[unused_idx].left, seq)) {
|
---|
| 2123 | pcb->rcv_sacks[unused_idx].left = seq;
|
---|
| 2124 | }
|
---|
| 2125 | ++unused_idx;
|
---|
| 2126 | }
|
---|
| 2127 | }
|
---|
| 2128 |
|
---|
| 2129 | /* We also need to invalidate everything from 'unused_idx' till the end */
|
---|
| 2130 | for (i = unused_idx; i < LWIP_TCP_MAX_SACK_NUM; ++i) {
|
---|
| 2131 | pcb->rcv_sacks[i].left = pcb->rcv_sacks[i].right = 0;
|
---|
| 2132 | }
|
---|
| 2133 | }
|
---|
| 2134 |
|
---|
| 2135 | #if defined(TCP_OOSEQ_BYTES_LIMIT) || defined(TCP_OOSEQ_PBUFS_LIMIT)
|
---|
| 2136 | /**
|
---|
| 2137 | * Called to remove a range of SACKs.
|
---|
| 2138 | *
|
---|
| 2139 | * SACK entries will be removed or adjusted to not acknowledge any sequence
|
---|
| 2140 | * numbers that are greater than (or equal to) 'seq' passed. It not only invalidates entries,
|
---|
| 2141 | * but also moves all entries that are still valid to the beginning.
|
---|
| 2142 | *
|
---|
| 2143 | * @param pcb the tcp_pcb to modify
|
---|
| 2144 | * @param seq the highest sequence number to keep in SACK entries
|
---|
| 2145 | */
|
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| 2146 | static void
|
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| 2147 | tcp_remove_sacks_gt(struct tcp_pcb *pcb, u32_t seq)
|
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| 2148 | {
|
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| 2149 | u8_t i;
|
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| 2150 | u8_t unused_idx;
|
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| 2151 |
|
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| 2152 | /* We run this loop for all entries, until we find the first invalid one.
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| 2153 | There is no point checking after that. */
|
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| 2154 | for (i = unused_idx = 0; (i < LWIP_TCP_MAX_SACK_NUM) && LWIP_TCP_SACK_VALID(pcb, i); ++i) {
|
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| 2155 | /* We only want to use SACK at index [i] if its left side is < 'seq'. */
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| 2156 | if (TCP_SEQ_LT(pcb->rcv_sacks[i].left, seq)) {
|
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| 2157 | if (unused_idx != i) {
|
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| 2158 | /* We only copy it if it's not in the right spot already. */
|
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| 2159 | pcb->rcv_sacks[unused_idx] = pcb->rcv_sacks[i];
|
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| 2160 | }
|
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| 2161 | /* NOTE: It is possible that its right side is > 'seq', in which case we should adjust it. */
|
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| 2162 | if (TCP_SEQ_GT(pcb->rcv_sacks[unused_idx].right, seq)) {
|
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| 2163 | pcb->rcv_sacks[unused_idx].right = seq;
|
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| 2164 | }
|
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| 2165 | ++unused_idx;
|
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| 2166 | }
|
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| 2167 | }
|
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| 2168 |
|
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| 2169 | /* We also need to invalidate everything from 'unused_idx' till the end */
|
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| 2170 | for (i = unused_idx; i < LWIP_TCP_MAX_SACK_NUM; ++i) {
|
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| 2171 | pcb->rcv_sacks[i].left = pcb->rcv_sacks[i].right = 0;
|
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| 2172 | }
|
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| 2173 | }
|
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| 2174 | #endif /* TCP_OOSEQ_BYTES_LIMIT || TCP_OOSEQ_PBUFS_LIMIT */
|
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| 2175 |
|
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| 2176 | #endif /* LWIP_TCP_SACK_OUT */
|
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| 2177 |
|
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| 2178 | #endif /* LWIP_TCP */
|
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