1 | /**
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2 | * @file
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3 | * Transmission Control Protocol, outgoing traffic
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4 | *
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5 | * The output functions of TCP.
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6 | *
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7 | */
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8 |
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9 | /*
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10 | * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
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11 | * All rights reserved.
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12 | *
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13 | * Redistribution and use in source and binary forms, with or without modification,
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14 | * are permitted provided that the following conditions are met:
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15 | *
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16 | * 1. Redistributions of source code must retain the above copyright notice,
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17 | * this list of conditions and the following disclaimer.
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18 | * 2. Redistributions in binary form must reproduce the above copyright notice,
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19 | * this list of conditions and the following disclaimer in the documentation
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20 | * and/or other materials provided with the distribution.
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21 | * 3. The name of the author may not be used to endorse or promote products
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22 | * derived from this software without specific prior written permission.
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23 | *
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24 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
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25 | * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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26 | * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
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27 | * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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28 | * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
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29 | * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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30 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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31 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
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32 | * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
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33 | * OF SUCH DAMAGE.
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34 | *
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35 | * This file is part of the lwIP TCP/IP stack.
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36 | *
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37 | * Author: Adam Dunkels <adam@sics.se>
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38 | *
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39 | */
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40 |
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41 | #include "lwip/opt.h"
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42 |
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43 | #if LWIP_TCP /* don't build if not configured for use in lwipopts.h */
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44 |
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45 | #include "lwip/tcp_impl.h"
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46 | #include "lwip/def.h"
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47 | #include "lwip/mem.h"
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48 | #include "lwip/memp.h"
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49 | #include "lwip/ip_addr.h"
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50 | #include "lwip/netif.h"
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51 | #include "lwip/inet_chksum.h"
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52 | #include "lwip/stats.h"
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53 | #include "lwip/snmp.h"
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54 | #if LWIP_TCP_TIMESTAMPS
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55 | #include "lwip/sys.h"
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56 | #endif
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57 |
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58 | #include <string.h>
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59 |
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60 | /* Define some copy-macros for checksum-on-copy so that the code looks
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61 | nicer by preventing too many ifdef's. */
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62 | #if TCP_CHECKSUM_ON_COPY
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63 | #define TCP_DATA_COPY(dst, src, len, seg) do { \
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64 | tcp_seg_add_chksum(LWIP_CHKSUM_COPY(dst, src, len), \
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65 | len, &seg->chksum, &seg->chksum_swapped); \
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66 | seg->flags |= TF_SEG_DATA_CHECKSUMMED; } while(0)
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67 | #define TCP_DATA_COPY2(dst, src, len, chksum, chksum_swapped) \
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68 | tcp_seg_add_chksum(LWIP_CHKSUM_COPY(dst, src, len), len, chksum, chksum_swapped);
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69 | #else /* TCP_CHECKSUM_ON_COPY*/
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70 | #define TCP_DATA_COPY(dst, src, len, seg) MEMCPY(dst, src, len)
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71 | #define TCP_DATA_COPY2(dst, src, len, chksum, chksum_swapped) MEMCPY(dst, src, len)
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72 | #endif /* TCP_CHECKSUM_ON_COPY*/
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73 |
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74 | /** Define this to 1 for an extra check that the output checksum is valid
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75 | * (usefule when the checksum is generated by the application, not the stack) */
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76 | #ifndef TCP_CHECKSUM_ON_COPY_SANITY_CHECK
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77 | #define TCP_CHECKSUM_ON_COPY_SANITY_CHECK 0
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78 | #endif
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79 |
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80 | /* Forward declarations.*/
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81 | static void tcp_output_segment(struct tcp_seg *seg, struct tcp_pcb *pcb);
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82 |
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83 | /** Allocate a pbuf and create a tcphdr at p->payload, used for output
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84 | * functions other than the default tcp_output -> tcp_output_segment
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85 | * (e.g. tcp_send_empty_ack, etc.)
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86 | *
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87 | * @param pcb tcp pcb for which to send a packet (used to initialize tcp_hdr)
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88 | * @param optlen length of header-options
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89 | * @param datalen length of tcp data to reserve in pbuf
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90 | * @param seqno_be seqno in network byte order (big-endian)
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91 | * @return pbuf with p->payload being the tcp_hdr
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92 | */
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93 | static struct pbuf *
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94 | tcp_output_alloc_header(struct tcp_pcb *pcb, u16_t optlen, u16_t datalen,
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95 | u32_t seqno_be /* already in network byte order */)
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96 | {
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97 | struct tcp_hdr *tcphdr;
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98 | struct pbuf *p = pbuf_alloc(PBUF_IP, TCP_HLEN + optlen + datalen, PBUF_RAM);
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99 | if (p != NULL) {
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100 | LWIP_ASSERT("check that first pbuf can hold struct tcp_hdr",
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101 | (p->len >= TCP_HLEN + optlen));
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102 | tcphdr = (struct tcp_hdr *)p->payload;
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103 | tcphdr->src = htons(pcb->local_port);
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104 | tcphdr->dest = htons(pcb->remote_port);
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105 | tcphdr->seqno = seqno_be;
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106 | tcphdr->ackno = htonl(pcb->rcv_nxt);
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107 | TCPH_HDRLEN_FLAGS_SET(tcphdr, (5 + optlen / 4), TCP_ACK);
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108 | tcphdr->wnd = htons(pcb->rcv_ann_wnd);
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109 | tcphdr->chksum = 0;
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110 | tcphdr->urgp = 0;
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111 |
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112 | /* If we're sending a packet, update the announced right window edge */
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113 | pcb->rcv_ann_right_edge = pcb->rcv_nxt + pcb->rcv_ann_wnd;
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114 | }
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115 | return p;
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116 | }
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117 |
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118 | /**
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119 | * Called by tcp_close() to send a segment including FIN flag but not data.
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120 | *
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121 | * @param pcb the tcp_pcb over which to send a segment
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122 | * @return ERR_OK if sent, another err_t otherwise
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123 | */
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124 | err_t
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125 | tcp_send_fin(struct tcp_pcb *pcb)
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126 | {
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127 | /* first, try to add the fin to the last unsent segment */
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128 | if (pcb->unsent != NULL) {
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129 | struct tcp_seg *last_unsent;
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130 | for (last_unsent = pcb->unsent; last_unsent->next != NULL;
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131 | last_unsent = last_unsent->next);
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132 |
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133 | if ((TCPH_FLAGS(last_unsent->tcphdr) & (TCP_SYN | TCP_FIN | TCP_RST)) == 0) {
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134 | /* no SYN/FIN/RST flag in the header, we can add the FIN flag */
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135 | TCPH_SET_FLAG(last_unsent->tcphdr, TCP_FIN);
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136 | pcb->flags |= TF_FIN;
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137 | return ERR_OK;
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138 | }
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139 | }
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140 | /* no data, no length, flags, copy=1, no optdata */
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141 | return tcp_enqueue_flags(pcb, TCP_FIN);
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142 | }
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143 |
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144 | /**
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145 | * Create a TCP segment with prefilled header.
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146 | *
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147 | * Called by tcp_write and tcp_enqueue_flags.
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148 | *
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149 | * @param pcb Protocol control block for the TCP connection.
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150 | * @param p pbuf that is used to hold the TCP header.
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151 | * @param flags TCP flags for header.
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152 | * @param seqno TCP sequence number of this packet
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153 | * @param optflags options to include in TCP header
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154 | * @return a new tcp_seg pointing to p, or NULL.
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155 | * The TCP header is filled in except ackno and wnd.
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156 | * p is freed on failure.
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157 | */
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158 | static struct tcp_seg *
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159 | tcp_create_segment(struct tcp_pcb *pcb, struct pbuf *p, u8_t flags, u32_t seqno, u8_t optflags)
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160 | {
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161 | struct tcp_seg *seg;
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162 | u8_t optlen = LWIP_TCP_OPT_LENGTH(optflags);
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163 |
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164 | if ((seg = (struct tcp_seg *)memp_malloc(MEMP_TCP_SEG)) == NULL) {
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165 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_create_segment: no memory.\n"));
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166 | pbuf_free(p);
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167 | return NULL;
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168 | }
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169 | seg->flags = optflags;
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170 | seg->next = NULL;
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171 | seg->p = p;
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172 | seg->len = p->tot_len - optlen;
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173 | #if TCP_OVERSIZE_DBGCHECK
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174 | seg->oversize_left = 0;
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175 | #endif /* TCP_OVERSIZE_DBGCHECK */
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176 | #if TCP_CHECKSUM_ON_COPY
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177 | seg->chksum = 0;
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178 | seg->chksum_swapped = 0;
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179 | /* check optflags */
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180 | LWIP_ASSERT("invalid optflags passed: TF_SEG_DATA_CHECKSUMMED",
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181 | (optflags & TF_SEG_DATA_CHECKSUMMED) == 0);
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182 | #endif /* TCP_CHECKSUM_ON_COPY */
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183 |
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184 | /* build TCP header */
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185 | if (pbuf_header(p, TCP_HLEN)) {
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186 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_create_segment: no room for TCP header in pbuf.\n"));
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187 | TCP_STATS_INC(tcp.err);
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188 | tcp_seg_free(seg);
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189 | return NULL;
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190 | }
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191 | seg->tcphdr = (struct tcp_hdr *)seg->p->payload;
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192 | seg->tcphdr->src = htons(pcb->local_port);
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193 | seg->tcphdr->dest = htons(pcb->remote_port);
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194 | seg->tcphdr->seqno = htonl(seqno);
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195 | /* ackno is set in tcp_output */
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196 | TCPH_HDRLEN_FLAGS_SET(seg->tcphdr, (5 + optlen / 4), flags);
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197 | /* wnd and chksum are set in tcp_output */
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198 | seg->tcphdr->urgp = 0;
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199 | return seg;
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200 | }
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201 |
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202 | /**
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203 | * Allocate a PBUF_RAM pbuf, perhaps with extra space at the end.
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204 | *
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205 | * This function is like pbuf_alloc(layer, length, PBUF_RAM) except
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206 | * there may be extra bytes available at the end.
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207 | *
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208 | * @param layer flag to define header size.
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209 | * @param length size of the pbuf's payload.
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210 | * @param max_length maximum usable size of payload+oversize.
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211 | * @param oversize pointer to a u16_t that will receive the number of usable tail bytes.
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212 | * @param pcb The TCP connection that willo enqueue the pbuf.
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213 | * @param apiflags API flags given to tcp_write.
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214 | * @param first_seg true when this pbuf will be used in the first enqueued segment.
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215 | * @param
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216 | */
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217 | #if TCP_OVERSIZE
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218 | static struct pbuf *
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219 | tcp_pbuf_prealloc(pbuf_layer layer, u16_t length, u16_t max_length,
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220 | u16_t *oversize, struct tcp_pcb *pcb, u8_t apiflags,
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221 | u8_t first_seg)
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222 | {
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223 | struct pbuf *p;
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224 | u16_t alloc = length;
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225 |
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226 | #if LWIP_NETIF_TX_SINGLE_PBUF
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227 | LWIP_UNUSED_ARG(max_length);
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228 | LWIP_UNUSED_ARG(pcb);
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229 | LWIP_UNUSED_ARG(apiflags);
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230 | LWIP_UNUSED_ARG(first_seg);
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231 | /* always create MSS-sized pbufs */
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232 | alloc = max_length;
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233 | #else /* LWIP_NETIF_TX_SINGLE_PBUF */
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234 | if (length < max_length) {
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235 | /* Should we allocate an oversized pbuf, or just the minimum
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236 | * length required? If tcp_write is going to be called again
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237 | * before this segment is transmitted, we want the oversized
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238 | * buffer. If the segment will be transmitted immediately, we can
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239 | * save memory by allocating only length. We use a simple
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240 | * heuristic based on the following information:
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241 | *
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242 | * Did the user set TCP_WRITE_FLAG_MORE?
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243 | *
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244 | * Will the Nagle algorithm defer transmission of this segment?
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245 | */
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246 | if ((apiflags & TCP_WRITE_FLAG_MORE) ||
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247 | (!(pcb->flags & TF_NODELAY) &&
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248 | (!first_seg ||
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249 | pcb->unsent != NULL ||
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250 | pcb->unacked != NULL))) {
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251 | alloc = LWIP_MIN(max_length, LWIP_MEM_ALIGN_SIZE(length + TCP_OVERSIZE));
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252 | }
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253 | }
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254 | #endif /* LWIP_NETIF_TX_SINGLE_PBUF */
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255 | p = pbuf_alloc(layer, alloc, PBUF_RAM);
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256 | if (p == NULL) {
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257 | return NULL;
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258 | }
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259 | LWIP_ASSERT("need unchained pbuf", p->next == NULL);
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260 | *oversize = p->len - length;
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261 | /* trim p->len to the currently used size */
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262 | p->len = p->tot_len = length;
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263 | return p;
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264 | }
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265 | #else /* TCP_OVERSIZE */
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266 | #define tcp_pbuf_prealloc(layer, length, mx, os, pcb, api, fst) pbuf_alloc((layer), (length), PBUF_RAM)
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267 | #endif /* TCP_OVERSIZE */
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268 |
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269 | #if TCP_CHECKSUM_ON_COPY
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270 | /** Add a checksum of newly added data to the segment */
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271 | static void
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272 | tcp_seg_add_chksum(u16_t chksum, u16_t len, u16_t *seg_chksum,
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273 | u8_t *seg_chksum_swapped)
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274 | {
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275 | u32_t helper;
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276 | /* add chksum to old chksum and fold to u16_t */
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277 | helper = chksum + *seg_chksum;
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278 | chksum = FOLD_U32T(helper);
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279 | if ((len & 1) != 0) {
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280 | *seg_chksum_swapped = 1 - *seg_chksum_swapped;
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281 | chksum = SWAP_BYTES_IN_WORD(chksum);
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282 | }
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283 | *seg_chksum = chksum;
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284 | }
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285 | #endif /* TCP_CHECKSUM_ON_COPY */
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286 |
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287 | /** Checks if tcp_write is allowed or not (checks state, snd_buf and snd_queuelen).
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288 | *
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289 | * @param pcb the tcp pcb to check for
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290 | * @param len length of data to send (checked agains snd_buf)
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291 | * @return ERR_OK if tcp_write is allowed to proceed, another err_t otherwise
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292 | */
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293 | static err_t
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294 | tcp_write_checks(struct tcp_pcb *pcb, u16_t len)
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295 | {
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296 | /* connection is in invalid state for data transmission? */
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297 | if ((pcb->state != ESTABLISHED) &&
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298 | (pcb->state != CLOSE_WAIT) &&
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299 | (pcb->state != SYN_SENT) &&
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300 | (pcb->state != SYN_RCVD)) {
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301 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_STATE | LWIP_DBG_LEVEL_SEVERE, ("tcp_write() called in invalid state\n"));
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302 | return ERR_CONN;
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303 | } else if (len == 0) {
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304 | return ERR_OK;
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305 | }
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306 |
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307 | /* fail on too much data */
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308 | if (len > pcb->snd_buf) {
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309 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 3, ("tcp_write: too much data (len=%"U16_F" > snd_buf=%"U16_F")\n",
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310 | len, pcb->snd_buf));
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311 | pcb->flags |= TF_NAGLEMEMERR;
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312 | return ERR_MEM;
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313 | }
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314 |
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315 | LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_write: queuelen: %"U16_F"\n", (u16_t)pcb->snd_queuelen));
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316 |
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317 | /* If total number of pbufs on the unsent/unacked queues exceeds the
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318 | * configured maximum, return an error */
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319 | /* check for configured max queuelen and possible overflow */
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320 | if ((pcb->snd_queuelen >= TCP_SND_QUEUELEN) || (pcb->snd_queuelen > TCP_SNDQUEUELEN_OVERFLOW)) {
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321 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 3, ("tcp_write: too long queue %"U16_F" (max %"U16_F")\n",
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322 | pcb->snd_queuelen, TCP_SND_QUEUELEN));
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323 | TCP_STATS_INC(tcp.memerr);
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324 | pcb->flags |= TF_NAGLEMEMERR;
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325 | return ERR_MEM;
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326 | }
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327 | if (pcb->snd_queuelen != 0) {
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328 | LWIP_ASSERT("tcp_write: pbufs on queue => at least one queue non-empty",
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329 | pcb->unacked != NULL || pcb->unsent != NULL);
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330 | } else {
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331 | LWIP_ASSERT("tcp_write: no pbufs on queue => both queues empty",
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332 | pcb->unacked == NULL && pcb->unsent == NULL);
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333 | }
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334 | return ERR_OK;
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335 | }
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336 |
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337 | /**
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338 | * Write data for sending (but does not send it immediately).
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339 | *
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340 | * It waits in the expectation of more data being sent soon (as
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341 | * it can send them more efficiently by combining them together).
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342 | * To prompt the system to send data now, call tcp_output() after
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343 | * calling tcp_write().
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344 | *
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345 | * @param pcb Protocol control block for the TCP connection to enqueue data for.
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346 | * @param arg Pointer to the data to be enqueued for sending.
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347 | * @param len Data length in bytes
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348 | * @param apiflags combination of following flags :
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349 | * - TCP_WRITE_FLAG_COPY (0x01) data will be copied into memory belonging to the stack
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350 | * - TCP_WRITE_FLAG_MORE (0x02) for TCP connection, PSH flag will be set on last segment sent,
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351 | * @return ERR_OK if enqueued, another err_t on error
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352 | */
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353 | err_t
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354 | tcp_write(struct tcp_pcb *pcb, const void *arg, u16_t len, u8_t apiflags)
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355 | {
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356 | struct pbuf *concat_p = NULL;
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357 | struct tcp_seg *last_unsent = NULL, *seg = NULL, *prev_seg = NULL, *queue = NULL;
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358 | u16_t pos = 0; /* position in 'arg' data */
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359 | u16_t queuelen;
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360 | u8_t optlen = 0;
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361 | u8_t optflags = 0;
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362 | #if TCP_OVERSIZE
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363 | u16_t oversize = 0;
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364 | u16_t oversize_used = 0;
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365 | #endif /* TCP_OVERSIZE */
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366 | #if TCP_CHECKSUM_ON_COPY
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367 | u16_t concat_chksum = 0;
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368 | u8_t concat_chksum_swapped = 0;
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369 | u16_t concat_chksummed = 0;
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370 | #endif /* TCP_CHECKSUM_ON_COPY */
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371 | err_t err;
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372 | /* don't allocate segments bigger than half the maximum window we ever received */
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373 | u16_t mss_local = LWIP_MIN(pcb->mss, pcb->snd_wnd_max/2);
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374 |
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375 | #if LWIP_NETIF_TX_SINGLE_PBUF
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376 | /* Always copy to try to create single pbufs for TX */
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377 | apiflags |= TCP_WRITE_FLAG_COPY;
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378 | #endif /* LWIP_NETIF_TX_SINGLE_PBUF */
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379 |
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380 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_write(pcb=%p, data=%p, len=%"U16_F", apiflags=%"U16_F")\n",
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381 | (void *)pcb, arg, len, (u16_t)apiflags));
|
---|
382 | LWIP_ERROR("tcp_write: arg == NULL (programmer violates API)",
|
---|
383 | arg != NULL, return ERR_ARG;);
|
---|
384 |
|
---|
385 | err = tcp_write_checks(pcb, len);
|
---|
386 | if (err != ERR_OK) {
|
---|
387 | return err;
|
---|
388 | }
|
---|
389 | queuelen = pcb->snd_queuelen;
|
---|
390 |
|
---|
391 | #if LWIP_TCP_TIMESTAMPS
|
---|
392 | if ((pcb->flags & TF_TIMESTAMP)) {
|
---|
393 | optflags = TF_SEG_OPTS_TS;
|
---|
394 | optlen = LWIP_TCP_OPT_LENGTH(TF_SEG_OPTS_TS);
|
---|
395 | }
|
---|
396 | #endif /* LWIP_TCP_TIMESTAMPS */
|
---|
397 |
|
---|
398 |
|
---|
399 | /*
|
---|
400 | * TCP segmentation is done in three phases with increasing complexity:
|
---|
401 | *
|
---|
402 | * 1. Copy data directly into an oversized pbuf.
|
---|
403 | * 2. Chain a new pbuf to the end of pcb->unsent.
|
---|
404 | * 3. Create new segments.
|
---|
405 | *
|
---|
406 | * We may run out of memory at any point. In that case we must
|
---|
407 | * return ERR_MEM and not change anything in pcb. Therefore, all
|
---|
408 | * changes are recorded in local variables and committed at the end
|
---|
409 | * of the function. Some pcb fields are maintained in local copies:
|
---|
410 | *
|
---|
411 | * queuelen = pcb->snd_queuelen
|
---|
412 | * oversize = pcb->unsent_oversize
|
---|
413 | *
|
---|
414 | * These variables are set consistently by the phases:
|
---|
415 | *
|
---|
416 | * seg points to the last segment tampered with.
|
---|
417 | *
|
---|
418 | * pos records progress as data is segmented.
|
---|
419 | */
|
---|
420 |
|
---|
421 | /* Find the tail of the unsent queue. */
|
---|
422 | if (pcb->unsent != NULL) {
|
---|
423 | u16_t space;
|
---|
424 | u16_t unsent_optlen;
|
---|
425 |
|
---|
426 | /* @todo: this could be sped up by keeping last_unsent in the pcb */
|
---|
427 | for (last_unsent = pcb->unsent; last_unsent->next != NULL;
|
---|
428 | last_unsent = last_unsent->next);
|
---|
429 |
|
---|
430 | /* Usable space at the end of the last unsent segment */
|
---|
431 | unsent_optlen = LWIP_TCP_OPT_LENGTH(last_unsent->flags);
|
---|
432 | space = mss_local - (last_unsent->len + unsent_optlen);
|
---|
433 |
|
---|
434 | /*
|
---|
435 | * Phase 1: Copy data directly into an oversized pbuf.
|
---|
436 | *
|
---|
437 | * The number of bytes copied is recorded in the oversize_used
|
---|
438 | * variable. The actual copying is done at the bottom of the
|
---|
439 | * function.
|
---|
440 | */
|
---|
441 | #if TCP_OVERSIZE
|
---|
442 | #if TCP_OVERSIZE_DBGCHECK
|
---|
443 | /* check that pcb->unsent_oversize matches last_unsent->unsent_oversize */
|
---|
444 | LWIP_ASSERT("unsent_oversize mismatch (pcb vs. last_unsent)",
|
---|
445 | pcb->unsent_oversize == last_unsent->oversize_left);
|
---|
446 | #endif /* TCP_OVERSIZE_DBGCHECK */
|
---|
447 | oversize = pcb->unsent_oversize;
|
---|
448 | if (oversize > 0) {
|
---|
449 | LWIP_ASSERT("inconsistent oversize vs. space", oversize_used <= space);
|
---|
450 | seg = last_unsent;
|
---|
451 | oversize_used = oversize < len ? oversize : len;
|
---|
452 | pos += oversize_used;
|
---|
453 | oversize -= oversize_used;
|
---|
454 | space -= oversize_used;
|
---|
455 | }
|
---|
456 | /* now we are either finished or oversize is zero */
|
---|
457 | LWIP_ASSERT("inconsistend oversize vs. len", (oversize == 0) || (pos == len));
|
---|
458 | #endif /* TCP_OVERSIZE */
|
---|
459 |
|
---|
460 | /*
|
---|
461 | * Phase 2: Chain a new pbuf to the end of pcb->unsent.
|
---|
462 | *
|
---|
463 | * We don't extend segments containing SYN/FIN flags or options
|
---|
464 | * (len==0). The new pbuf is kept in concat_p and pbuf_cat'ed at
|
---|
465 | * the end.
|
---|
466 | */
|
---|
467 | if ((pos < len) && (space > 0) && (last_unsent->len > 0)) {
|
---|
468 | u16_t seglen = space < len - pos ? space : len - pos;
|
---|
469 | seg = last_unsent;
|
---|
470 |
|
---|
471 | /* Create a pbuf with a copy or reference to seglen bytes. We
|
---|
472 | * can use PBUF_RAW here since the data appears in the middle of
|
---|
473 | * a segment. A header will never be prepended. */
|
---|
474 | if (apiflags & TCP_WRITE_FLAG_COPY) {
|
---|
475 | /* Data is copied */
|
---|
476 | if ((concat_p = tcp_pbuf_prealloc(PBUF_RAW, seglen, space, &oversize, pcb, apiflags, 1)) == NULL) {
|
---|
477 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2,
|
---|
478 | ("tcp_write : could not allocate memory for pbuf copy size %"U16_F"\n",
|
---|
479 | seglen));
|
---|
480 | goto memerr;
|
---|
481 | }
|
---|
482 | #if TCP_OVERSIZE_DBGCHECK
|
---|
483 | last_unsent->oversize_left += oversize;
|
---|
484 | #endif /* TCP_OVERSIZE_DBGCHECK */
|
---|
485 | TCP_DATA_COPY2(concat_p->payload, (u8_t*)arg + pos, seglen, &concat_chksum, &concat_chksum_swapped);
|
---|
486 | #if TCP_CHECKSUM_ON_COPY
|
---|
487 | concat_chksummed += seglen;
|
---|
488 | #endif /* TCP_CHECKSUM_ON_COPY */
|
---|
489 | } else {
|
---|
490 | /* Data is not copied */
|
---|
491 | if ((concat_p = pbuf_alloc(PBUF_RAW, seglen, PBUF_ROM)) == NULL) {
|
---|
492 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2,
|
---|
493 | ("tcp_write: could not allocate memory for zero-copy pbuf\n"));
|
---|
494 | goto memerr;
|
---|
495 | }
|
---|
496 | #if TCP_CHECKSUM_ON_COPY
|
---|
497 | /* calculate the checksum of nocopy-data */
|
---|
498 | tcp_seg_add_chksum(~inet_chksum((u8_t*)arg + pos, seglen), seglen,
|
---|
499 | &concat_chksum, &concat_chksum_swapped);
|
---|
500 | concat_chksummed += seglen;
|
---|
501 | #endif /* TCP_CHECKSUM_ON_COPY */
|
---|
502 | /* reference the non-volatile payload data */
|
---|
503 | concat_p->payload = (u8_t*)arg + pos;
|
---|
504 | }
|
---|
505 |
|
---|
506 | pos += seglen;
|
---|
507 | queuelen += pbuf_clen(concat_p);
|
---|
508 | }
|
---|
509 | } else {
|
---|
510 | #if TCP_OVERSIZE
|
---|
511 | LWIP_ASSERT("unsent_oversize mismatch (pcb->unsent is NULL)",
|
---|
512 | pcb->unsent_oversize == 0);
|
---|
513 | #endif /* TCP_OVERSIZE */
|
---|
514 | }
|
---|
515 |
|
---|
516 | /*
|
---|
517 | * Phase 3: Create new segments.
|
---|
518 | *
|
---|
519 | * The new segments are chained together in the local 'queue'
|
---|
520 | * variable, ready to be appended to pcb->unsent.
|
---|
521 | */
|
---|
522 | while (pos < len) {
|
---|
523 | struct pbuf *p;
|
---|
524 | u16_t left = len - pos;
|
---|
525 | u16_t max_len = mss_local - optlen;
|
---|
526 | u16_t seglen = left > max_len ? max_len : left;
|
---|
527 | #if TCP_CHECKSUM_ON_COPY
|
---|
528 | u16_t chksum = 0;
|
---|
529 | u8_t chksum_swapped = 0;
|
---|
530 | #endif /* TCP_CHECKSUM_ON_COPY */
|
---|
531 |
|
---|
532 | if (apiflags & TCP_WRITE_FLAG_COPY) {
|
---|
533 | /* If copy is set, memory should be allocated and data copied
|
---|
534 | * into pbuf */
|
---|
535 | if ((p = tcp_pbuf_prealloc(PBUF_TRANSPORT, seglen + optlen, mss_local, &oversize, pcb, apiflags, queue == NULL)) == NULL) {
|
---|
536 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_write : could not allocate memory for pbuf copy size %"U16_F"\n", seglen));
|
---|
537 | goto memerr;
|
---|
538 | }
|
---|
539 | LWIP_ASSERT("tcp_write: check that first pbuf can hold the complete seglen",
|
---|
540 | (p->len >= seglen));
|
---|
541 | TCP_DATA_COPY2((char *)p->payload + optlen, (u8_t*)arg + pos, seglen, &chksum, &chksum_swapped);
|
---|
542 | } else {
|
---|
543 | /* Copy is not set: First allocate a pbuf for holding the data.
|
---|
544 | * Since the referenced data is available at least until it is
|
---|
545 | * sent out on the link (as it has to be ACKed by the remote
|
---|
546 | * party) we can safely use PBUF_ROM instead of PBUF_REF here.
|
---|
547 | */
|
---|
548 | struct pbuf *p2;
|
---|
549 | #if TCP_OVERSIZE
|
---|
550 | LWIP_ASSERT("oversize == 0", oversize == 0);
|
---|
551 | #endif /* TCP_OVERSIZE */
|
---|
552 | if ((p2 = pbuf_alloc(PBUF_TRANSPORT, seglen, PBUF_ROM)) == NULL) {
|
---|
553 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_write: could not allocate memory for zero-copy pbuf\n"));
|
---|
554 | goto memerr;
|
---|
555 | }
|
---|
556 | #if TCP_CHECKSUM_ON_COPY
|
---|
557 | /* calculate the checksum of nocopy-data */
|
---|
558 | chksum = ~inet_chksum((u8_t*)arg + pos, seglen);
|
---|
559 | #endif /* TCP_CHECKSUM_ON_COPY */
|
---|
560 | /* reference the non-volatile payload data */
|
---|
561 | p2->payload = (u8_t*)arg + pos;
|
---|
562 |
|
---|
563 | /* Second, allocate a pbuf for the headers. */
|
---|
564 | if ((p = pbuf_alloc(PBUF_TRANSPORT, optlen, PBUF_RAM)) == NULL) {
|
---|
565 | /* If allocation fails, we have to deallocate the data pbuf as
|
---|
566 | * well. */
|
---|
567 | pbuf_free(p2);
|
---|
568 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_write: could not allocate memory for header pbuf\n"));
|
---|
569 | goto memerr;
|
---|
570 | }
|
---|
571 | /* Concatenate the headers and data pbufs together. */
|
---|
572 | pbuf_cat(p/*header*/, p2/*data*/);
|
---|
573 | }
|
---|
574 |
|
---|
575 | queuelen += pbuf_clen(p);
|
---|
576 |
|
---|
577 | /* Now that there are more segments queued, we check again if the
|
---|
578 | * length of the queue exceeds the configured maximum or
|
---|
579 | * overflows. */
|
---|
580 | if ((queuelen > TCP_SND_QUEUELEN) || (queuelen > TCP_SNDQUEUELEN_OVERFLOW)) {
|
---|
581 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_write: queue too long %"U16_F" (%"U16_F")\n", queuelen, TCP_SND_QUEUELEN));
|
---|
582 | pbuf_free(p);
|
---|
583 | goto memerr;
|
---|
584 | }
|
---|
585 |
|
---|
586 | if ((seg = tcp_create_segment(pcb, p, 0, pcb->snd_lbb + pos, optflags)) == NULL) {
|
---|
587 | goto memerr;
|
---|
588 | }
|
---|
589 | #if TCP_OVERSIZE_DBGCHECK
|
---|
590 | seg->oversize_left = oversize;
|
---|
591 | #endif /* TCP_OVERSIZE_DBGCHECK */
|
---|
592 | #if TCP_CHECKSUM_ON_COPY
|
---|
593 | seg->chksum = chksum;
|
---|
594 | seg->chksum_swapped = chksum_swapped;
|
---|
595 | seg->flags |= TF_SEG_DATA_CHECKSUMMED;
|
---|
596 | #endif /* TCP_CHECKSUM_ON_COPY */
|
---|
597 |
|
---|
598 | /* first segment of to-be-queued data? */
|
---|
599 | if (queue == NULL) {
|
---|
600 | queue = seg;
|
---|
601 | } else {
|
---|
602 | /* Attach the segment to the end of the queued segments */
|
---|
603 | LWIP_ASSERT("prev_seg != NULL", prev_seg != NULL);
|
---|
604 | prev_seg->next = seg;
|
---|
605 | }
|
---|
606 | /* remember last segment of to-be-queued data for next iteration */
|
---|
607 | prev_seg = seg;
|
---|
608 |
|
---|
609 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_TRACE, ("tcp_write: queueing %"U32_F":%"U32_F"\n",
|
---|
610 | ntohl(seg->tcphdr->seqno),
|
---|
611 | ntohl(seg->tcphdr->seqno) + TCP_TCPLEN(seg)));
|
---|
612 |
|
---|
613 | pos += seglen;
|
---|
614 | }
|
---|
615 |
|
---|
616 | /*
|
---|
617 | * All three segmentation phases were successful. We can commit the
|
---|
618 | * transaction.
|
---|
619 | */
|
---|
620 |
|
---|
621 | /*
|
---|
622 | * Phase 1: If data has been added to the preallocated tail of
|
---|
623 | * last_unsent, we update the length fields of the pbuf chain.
|
---|
624 | */
|
---|
625 | #if TCP_OVERSIZE
|
---|
626 | if (oversize_used > 0) {
|
---|
627 | struct pbuf *p;
|
---|
628 | /* Bump tot_len of whole chain, len of tail */
|
---|
629 | for (p = last_unsent->p; p; p = p->next) {
|
---|
630 | p->tot_len += oversize_used;
|
---|
631 | if (p->next == NULL) {
|
---|
632 | TCP_DATA_COPY((char *)p->payload + p->len, arg, oversize_used, last_unsent);
|
---|
633 | p->len += oversize_used;
|
---|
634 | }
|
---|
635 | }
|
---|
636 | last_unsent->len += oversize_used;
|
---|
637 | #if TCP_OVERSIZE_DBGCHECK
|
---|
638 | LWIP_ASSERT("last_unsent->oversize_left >= oversize_used",
|
---|
639 | last_unsent->oversize_left >= oversize_used);
|
---|
640 | last_unsent->oversize_left -= oversize_used;
|
---|
641 | #endif /* TCP_OVERSIZE_DBGCHECK */
|
---|
642 | }
|
---|
643 | pcb->unsent_oversize = oversize;
|
---|
644 | #endif /* TCP_OVERSIZE */
|
---|
645 |
|
---|
646 | /*
|
---|
647 | * Phase 2: concat_p can be concatenated onto last_unsent->p
|
---|
648 | */
|
---|
649 | if (concat_p != NULL) {
|
---|
650 | LWIP_ASSERT("tcp_write: cannot concatenate when pcb->unsent is empty",
|
---|
651 | (last_unsent != NULL));
|
---|
652 | pbuf_cat(last_unsent->p, concat_p);
|
---|
653 | last_unsent->len += concat_p->tot_len;
|
---|
654 | #if TCP_CHECKSUM_ON_COPY
|
---|
655 | if (concat_chksummed) {
|
---|
656 | tcp_seg_add_chksum(concat_chksum, concat_chksummed, &last_unsent->chksum,
|
---|
657 | &last_unsent->chksum_swapped);
|
---|
658 | last_unsent->flags |= TF_SEG_DATA_CHECKSUMMED;
|
---|
659 | }
|
---|
660 | #endif /* TCP_CHECKSUM_ON_COPY */
|
---|
661 | }
|
---|
662 |
|
---|
663 | /*
|
---|
664 | * Phase 3: Append queue to pcb->unsent. Queue may be NULL, but that
|
---|
665 | * is harmless
|
---|
666 | */
|
---|
667 | if (last_unsent == NULL) {
|
---|
668 | pcb->unsent = queue;
|
---|
669 | } else {
|
---|
670 | last_unsent->next = queue;
|
---|
671 | }
|
---|
672 |
|
---|
673 | /*
|
---|
674 | * Finally update the pcb state.
|
---|
675 | */
|
---|
676 | pcb->snd_lbb += len;
|
---|
677 | pcb->snd_buf -= len;
|
---|
678 | pcb->snd_queuelen = queuelen;
|
---|
679 |
|
---|
680 | LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_write: %"S16_F" (after enqueued)\n",
|
---|
681 | pcb->snd_queuelen));
|
---|
682 | if (pcb->snd_queuelen != 0) {
|
---|
683 | LWIP_ASSERT("tcp_write: valid queue length",
|
---|
684 | pcb->unacked != NULL || pcb->unsent != NULL);
|
---|
685 | }
|
---|
686 |
|
---|
687 | /* Set the PSH flag in the last segment that we enqueued. */
|
---|
688 | if (seg != NULL && seg->tcphdr != NULL && ((apiflags & TCP_WRITE_FLAG_MORE)==0)) {
|
---|
689 | TCPH_SET_FLAG(seg->tcphdr, TCP_PSH);
|
---|
690 | }
|
---|
691 |
|
---|
692 | return ERR_OK;
|
---|
693 | memerr:
|
---|
694 | pcb->flags |= TF_NAGLEMEMERR;
|
---|
695 | TCP_STATS_INC(tcp.memerr);
|
---|
696 |
|
---|
697 | if (concat_p != NULL) {
|
---|
698 | pbuf_free(concat_p);
|
---|
699 | }
|
---|
700 | if (queue != NULL) {
|
---|
701 | tcp_segs_free(queue);
|
---|
702 | }
|
---|
703 | if (pcb->snd_queuelen != 0) {
|
---|
704 | LWIP_ASSERT("tcp_write: valid queue length", pcb->unacked != NULL ||
|
---|
705 | pcb->unsent != NULL);
|
---|
706 | }
|
---|
707 | LWIP_DEBUGF(TCP_QLEN_DEBUG | LWIP_DBG_STATE, ("tcp_write: %"S16_F" (with mem err)\n", pcb->snd_queuelen));
|
---|
708 | return ERR_MEM;
|
---|
709 | }
|
---|
710 |
|
---|
711 | /**
|
---|
712 | * Enqueue TCP options for transmission.
|
---|
713 | *
|
---|
714 | * Called by tcp_connect(), tcp_listen_input(), and tcp_send_ctrl().
|
---|
715 | *
|
---|
716 | * @param pcb Protocol control block for the TCP connection.
|
---|
717 | * @param flags TCP header flags to set in the outgoing segment.
|
---|
718 | * @param optdata pointer to TCP options, or NULL.
|
---|
719 | * @param optlen length of TCP options in bytes.
|
---|
720 | */
|
---|
721 | err_t
|
---|
722 | tcp_enqueue_flags(struct tcp_pcb *pcb, u8_t flags)
|
---|
723 | {
|
---|
724 | struct pbuf *p;
|
---|
725 | struct tcp_seg *seg;
|
---|
726 | u8_t optflags = 0;
|
---|
727 | u8_t optlen = 0;
|
---|
728 |
|
---|
729 | LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_enqueue_flags: queuelen: %"U16_F"\n", (u16_t)pcb->snd_queuelen));
|
---|
730 |
|
---|
731 | LWIP_ASSERT("tcp_enqueue_flags: need either TCP_SYN or TCP_FIN in flags (programmer violates API)",
|
---|
732 | (flags & (TCP_SYN | TCP_FIN)) != 0);
|
---|
733 |
|
---|
734 | /* check for configured max queuelen and possible overflow */
|
---|
735 | if ((pcb->snd_queuelen >= TCP_SND_QUEUELEN) || (pcb->snd_queuelen > TCP_SNDQUEUELEN_OVERFLOW)) {
|
---|
736 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 3, ("tcp_enqueue_flags: too long queue %"U16_F" (max %"U16_F")\n",
|
---|
737 | pcb->snd_queuelen, TCP_SND_QUEUELEN));
|
---|
738 | TCP_STATS_INC(tcp.memerr);
|
---|
739 | pcb->flags |= TF_NAGLEMEMERR;
|
---|
740 | return ERR_MEM;
|
---|
741 | }
|
---|
742 |
|
---|
743 | if (flags & TCP_SYN) {
|
---|
744 | optflags = TF_SEG_OPTS_MSS;
|
---|
745 | }
|
---|
746 | #if LWIP_TCP_TIMESTAMPS
|
---|
747 | if ((pcb->flags & TF_TIMESTAMP)) {
|
---|
748 | optflags |= TF_SEG_OPTS_TS;
|
---|
749 | }
|
---|
750 | #endif /* LWIP_TCP_TIMESTAMPS */
|
---|
751 | optlen = LWIP_TCP_OPT_LENGTH(optflags);
|
---|
752 |
|
---|
753 | /* tcp_enqueue_flags is always called with either SYN or FIN in flags.
|
---|
754 | * We need one available snd_buf byte to do that.
|
---|
755 | * This means we can't send FIN while snd_buf==0. A better fix would be to
|
---|
756 | * not include SYN and FIN sequence numbers in the snd_buf count. */
|
---|
757 | if (pcb->snd_buf == 0) {
|
---|
758 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 3, ("tcp_enqueue_flags: no send buffer available\n"));
|
---|
759 | TCP_STATS_INC(tcp.memerr);
|
---|
760 | return ERR_MEM;
|
---|
761 | }
|
---|
762 |
|
---|
763 | /* Allocate pbuf with room for TCP header + options */
|
---|
764 | if ((p = pbuf_alloc(PBUF_TRANSPORT, optlen, PBUF_RAM)) == NULL) {
|
---|
765 | pcb->flags |= TF_NAGLEMEMERR;
|
---|
766 | TCP_STATS_INC(tcp.memerr);
|
---|
767 | return ERR_MEM;
|
---|
768 | }
|
---|
769 | LWIP_ASSERT("tcp_enqueue_flags: check that first pbuf can hold optlen",
|
---|
770 | (p->len >= optlen));
|
---|
771 |
|
---|
772 | /* Allocate memory for tcp_seg, and fill in fields. */
|
---|
773 | if ((seg = tcp_create_segment(pcb, p, flags, pcb->snd_lbb, optflags)) == NULL) {
|
---|
774 | pcb->flags |= TF_NAGLEMEMERR;
|
---|
775 | TCP_STATS_INC(tcp.memerr);
|
---|
776 | return ERR_MEM;
|
---|
777 | }
|
---|
778 | LWIP_ASSERT("seg->tcphdr not aligned", ((mem_ptr_t)seg->tcphdr % MEM_ALIGNMENT) == 0);
|
---|
779 | LWIP_ASSERT("tcp_enqueue_flags: invalid segment length", seg->len == 0);
|
---|
780 |
|
---|
781 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_TRACE,
|
---|
782 | ("tcp_enqueue_flags: queueing %"U32_F":%"U32_F" (0x%"X16_F")\n",
|
---|
783 | ntohl(seg->tcphdr->seqno),
|
---|
784 | ntohl(seg->tcphdr->seqno) + TCP_TCPLEN(seg),
|
---|
785 | (u16_t)flags));
|
---|
786 |
|
---|
787 | /* Now append seg to pcb->unsent queue */
|
---|
788 | if (pcb->unsent == NULL) {
|
---|
789 | pcb->unsent = seg;
|
---|
790 | } else {
|
---|
791 | struct tcp_seg *useg;
|
---|
792 | for (useg = pcb->unsent; useg->next != NULL; useg = useg->next);
|
---|
793 | useg->next = seg;
|
---|
794 | }
|
---|
795 | #if TCP_OVERSIZE
|
---|
796 | /* The new unsent tail has no space */
|
---|
797 | pcb->unsent_oversize = 0;
|
---|
798 | #endif /* TCP_OVERSIZE */
|
---|
799 |
|
---|
800 | /* SYN and FIN bump the sequence number */
|
---|
801 | if ((flags & TCP_SYN) || (flags & TCP_FIN)) {
|
---|
802 | pcb->snd_lbb++;
|
---|
803 | /* optlen does not influence snd_buf */
|
---|
804 | pcb->snd_buf--;
|
---|
805 | }
|
---|
806 | if (flags & TCP_FIN) {
|
---|
807 | pcb->flags |= TF_FIN;
|
---|
808 | }
|
---|
809 |
|
---|
810 | /* update number of segments on the queues */
|
---|
811 | pcb->snd_queuelen += pbuf_clen(seg->p);
|
---|
812 | LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_enqueue_flags: %"S16_F" (after enqueued)\n", pcb->snd_queuelen));
|
---|
813 | if (pcb->snd_queuelen != 0) {
|
---|
814 | LWIP_ASSERT("tcp_enqueue_flags: invalid queue length",
|
---|
815 | pcb->unacked != NULL || pcb->unsent != NULL);
|
---|
816 | }
|
---|
817 |
|
---|
818 | return ERR_OK;
|
---|
819 | }
|
---|
820 |
|
---|
821 | #if LWIP_TCP_TIMESTAMPS
|
---|
822 | /* Build a timestamp option (12 bytes long) at the specified options pointer)
|
---|
823 | *
|
---|
824 | * @param pcb tcp_pcb
|
---|
825 | * @param opts option pointer where to store the timestamp option
|
---|
826 | */
|
---|
827 | static void
|
---|
828 | tcp_build_timestamp_option(struct tcp_pcb *pcb, u32_t *opts)
|
---|
829 | {
|
---|
830 | /* Pad with two NOP options to make everything nicely aligned */
|
---|
831 | opts[0] = PP_HTONL(0x0101080A);
|
---|
832 | opts[1] = htonl(sys_now());
|
---|
833 | opts[2] = htonl(pcb->ts_recent);
|
---|
834 | }
|
---|
835 | #endif
|
---|
836 |
|
---|
837 | /** Send an ACK without data.
|
---|
838 | *
|
---|
839 | * @param pcb Protocol control block for the TCP connection to send the ACK
|
---|
840 | */
|
---|
841 | err_t
|
---|
842 | tcp_send_empty_ack(struct tcp_pcb *pcb)
|
---|
843 | {
|
---|
844 | struct pbuf *p;
|
---|
845 | struct tcp_hdr *tcphdr;
|
---|
846 | u8_t optlen = 0;
|
---|
847 |
|
---|
848 | #if LWIP_TCP_TIMESTAMPS
|
---|
849 | if (pcb->flags & TF_TIMESTAMP) {
|
---|
850 | optlen = LWIP_TCP_OPT_LENGTH(TF_SEG_OPTS_TS);
|
---|
851 | }
|
---|
852 | #endif
|
---|
853 |
|
---|
854 | p = tcp_output_alloc_header(pcb, optlen, 0, htonl(pcb->snd_nxt));
|
---|
855 | if (p == NULL) {
|
---|
856 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output: (ACK) could not allocate pbuf\n"));
|
---|
857 | return ERR_BUF;
|
---|
858 | }
|
---|
859 | tcphdr = (struct tcp_hdr *)p->payload;
|
---|
860 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG,
|
---|
861 | ("tcp_output: sending ACK for %"U32_F"\n", pcb->rcv_nxt));
|
---|
862 | /* remove ACK flags from the PCB, as we send an empty ACK now */
|
---|
863 | pcb->flags &= ~(TF_ACK_DELAY | TF_ACK_NOW);
|
---|
864 |
|
---|
865 | /* NB. MSS option is only sent on SYNs, so ignore it here */
|
---|
866 | #if LWIP_TCP_TIMESTAMPS
|
---|
867 | pcb->ts_lastacksent = pcb->rcv_nxt;
|
---|
868 |
|
---|
869 | if (pcb->flags & TF_TIMESTAMP) {
|
---|
870 | tcp_build_timestamp_option(pcb, (u32_t *)(tcphdr + 1));
|
---|
871 | }
|
---|
872 | #endif
|
---|
873 |
|
---|
874 | #if CHECKSUM_GEN_TCP
|
---|
875 | tcphdr->chksum = inet_chksum_pseudo(p, &(pcb->local_ip), &(pcb->remote_ip),
|
---|
876 | IP_PROTO_TCP, p->tot_len);
|
---|
877 | #endif
|
---|
878 | #if LWIP_NETIF_HWADDRHINT
|
---|
879 | ip_output_hinted(p, &(pcb->local_ip), &(pcb->remote_ip), pcb->ttl, pcb->tos,
|
---|
880 | IP_PROTO_TCP, &(pcb->addr_hint));
|
---|
881 | #else /* LWIP_NETIF_HWADDRHINT*/
|
---|
882 | ip_output(p, &(pcb->local_ip), &(pcb->remote_ip), pcb->ttl, pcb->tos,
|
---|
883 | IP_PROTO_TCP);
|
---|
884 | #endif /* LWIP_NETIF_HWADDRHINT*/
|
---|
885 | pbuf_free(p);
|
---|
886 |
|
---|
887 | return ERR_OK;
|
---|
888 | }
|
---|
889 |
|
---|
890 | /**
|
---|
891 | * Find out what we can send and send it
|
---|
892 | *
|
---|
893 | * @param pcb Protocol control block for the TCP connection to send data
|
---|
894 | * @return ERR_OK if data has been sent or nothing to send
|
---|
895 | * another err_t on error
|
---|
896 | */
|
---|
897 | err_t
|
---|
898 | tcp_output(struct tcp_pcb *pcb)
|
---|
899 | {
|
---|
900 | struct tcp_seg *seg, *useg;
|
---|
901 | u32_t wnd, snd_nxt;
|
---|
902 | #if TCP_CWND_DEBUG
|
---|
903 | s16_t i = 0;
|
---|
904 | #endif /* TCP_CWND_DEBUG */
|
---|
905 |
|
---|
906 | /* pcb->state LISTEN not allowed here */
|
---|
907 | LWIP_ASSERT("don't call tcp_output for listen-pcbs",
|
---|
908 | pcb->state != LISTEN);
|
---|
909 |
|
---|
910 | /* First, check if we are invoked by the TCP input processing
|
---|
911 | code. If so, we do not output anything. Instead, we rely on the
|
---|
912 | input processing code to call us when input processing is done
|
---|
913 | with. */
|
---|
914 | if (tcp_input_pcb == pcb) {
|
---|
915 | return ERR_OK;
|
---|
916 | }
|
---|
917 |
|
---|
918 | wnd = LWIP_MIN(pcb->snd_wnd, pcb->cwnd);
|
---|
919 |
|
---|
920 | seg = pcb->unsent;
|
---|
921 |
|
---|
922 | /* If the TF_ACK_NOW flag is set and no data will be sent (either
|
---|
923 | * because the ->unsent queue is empty or because the window does
|
---|
924 | * not allow it), construct an empty ACK segment and send it.
|
---|
925 | *
|
---|
926 | * If data is to be sent, we will just piggyback the ACK (see below).
|
---|
927 | */
|
---|
928 | if (pcb->flags & TF_ACK_NOW &&
|
---|
929 | (seg == NULL ||
|
---|
930 | ntohl(seg->tcphdr->seqno) - pcb->lastack + seg->len > wnd)) {
|
---|
931 | return tcp_send_empty_ack(pcb);
|
---|
932 | }
|
---|
933 |
|
---|
934 | /* useg should point to last segment on unacked queue */
|
---|
935 | useg = pcb->unacked;
|
---|
936 | if (useg != NULL) {
|
---|
937 | for (; useg->next != NULL; useg = useg->next);
|
---|
938 | }
|
---|
939 |
|
---|
940 | #if TCP_OUTPUT_DEBUG
|
---|
941 | if (seg == NULL) {
|
---|
942 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output: nothing to send (%p)\n",
|
---|
943 | (void*)pcb->unsent));
|
---|
944 | }
|
---|
945 | #endif /* TCP_OUTPUT_DEBUG */
|
---|
946 | #if TCP_CWND_DEBUG
|
---|
947 | if (seg == NULL) {
|
---|
948 | LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_output: snd_wnd %"U16_F
|
---|
949 | ", cwnd %"U16_F", wnd %"U32_F
|
---|
950 | ", seg == NULL, ack %"U32_F"\n",
|
---|
951 | pcb->snd_wnd, pcb->cwnd, wnd, pcb->lastack));
|
---|
952 | } else {
|
---|
953 | LWIP_DEBUGF(TCP_CWND_DEBUG,
|
---|
954 | ("tcp_output: snd_wnd %"U16_F", cwnd %"U16_F", wnd %"U32_F
|
---|
955 | ", effwnd %"U32_F", seq %"U32_F", ack %"U32_F"\n",
|
---|
956 | pcb->snd_wnd, pcb->cwnd, wnd,
|
---|
957 | ntohl(seg->tcphdr->seqno) - pcb->lastack + seg->len,
|
---|
958 | ntohl(seg->tcphdr->seqno), pcb->lastack));
|
---|
959 | }
|
---|
960 | #endif /* TCP_CWND_DEBUG */
|
---|
961 | /* data available and window allows it to be sent? */
|
---|
962 | while (seg != NULL &&
|
---|
963 | ntohl(seg->tcphdr->seqno) - pcb->lastack + seg->len <= wnd) {
|
---|
964 | LWIP_ASSERT("RST not expected here!",
|
---|
965 | (TCPH_FLAGS(seg->tcphdr) & TCP_RST) == 0);
|
---|
966 | /* Stop sending if the nagle algorithm would prevent it
|
---|
967 | * Don't stop:
|
---|
968 | * - if tcp_write had a memory error before (prevent delayed ACK timeout) or
|
---|
969 | * - if FIN was already enqueued for this PCB (SYN is always alone in a segment -
|
---|
970 | * either seg->next != NULL or pcb->unacked == NULL;
|
---|
971 | * RST is no sent using tcp_write/tcp_output.
|
---|
972 | */
|
---|
973 | if((tcp_do_output_nagle(pcb) == 0) &&
|
---|
974 | ((pcb->flags & (TF_NAGLEMEMERR | TF_FIN)) == 0)){
|
---|
975 | break;
|
---|
976 | }
|
---|
977 | #if TCP_CWND_DEBUG
|
---|
978 | LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_output: snd_wnd %"U16_F", cwnd %"U16_F", wnd %"U32_F", effwnd %"U32_F", seq %"U32_F", ack %"U32_F", i %"S16_F"\n",
|
---|
979 | pcb->snd_wnd, pcb->cwnd, wnd,
|
---|
980 | ntohl(seg->tcphdr->seqno) + seg->len -
|
---|
981 | pcb->lastack,
|
---|
982 | ntohl(seg->tcphdr->seqno), pcb->lastack, i));
|
---|
983 | ++i;
|
---|
984 | #endif /* TCP_CWND_DEBUG */
|
---|
985 |
|
---|
986 | pcb->unsent = seg->next;
|
---|
987 |
|
---|
988 | if (pcb->state != SYN_SENT) {
|
---|
989 | TCPH_SET_FLAG(seg->tcphdr, TCP_ACK);
|
---|
990 | pcb->flags &= ~(TF_ACK_DELAY | TF_ACK_NOW);
|
---|
991 | }
|
---|
992 |
|
---|
993 | tcp_output_segment(seg, pcb);
|
---|
994 | snd_nxt = ntohl(seg->tcphdr->seqno) + TCP_TCPLEN(seg);
|
---|
995 | if (TCP_SEQ_LT(pcb->snd_nxt, snd_nxt)) {
|
---|
996 | pcb->snd_nxt = snd_nxt;
|
---|
997 | }
|
---|
998 | /* put segment on unacknowledged list if length > 0 */
|
---|
999 | if (TCP_TCPLEN(seg) > 0) {
|
---|
1000 | seg->next = NULL;
|
---|
1001 | /* unacked list is empty? */
|
---|
1002 | if (pcb->unacked == NULL) {
|
---|
1003 | pcb->unacked = seg;
|
---|
1004 | useg = seg;
|
---|
1005 | /* unacked list is not empty? */
|
---|
1006 | } else {
|
---|
1007 | /* In the case of fast retransmit, the packet should not go to the tail
|
---|
1008 | * of the unacked queue, but rather somewhere before it. We need to check for
|
---|
1009 | * this case. -STJ Jul 27, 2004 */
|
---|
1010 | if (TCP_SEQ_LT(ntohl(seg->tcphdr->seqno), ntohl(useg->tcphdr->seqno))) {
|
---|
1011 | /* add segment to before tail of unacked list, keeping the list sorted */
|
---|
1012 | struct tcp_seg **cur_seg = &(pcb->unacked);
|
---|
1013 | while (*cur_seg &&
|
---|
1014 | TCP_SEQ_LT(ntohl((*cur_seg)->tcphdr->seqno), ntohl(seg->tcphdr->seqno))) {
|
---|
1015 | cur_seg = &((*cur_seg)->next );
|
---|
1016 | }
|
---|
1017 | seg->next = (*cur_seg);
|
---|
1018 | (*cur_seg) = seg;
|
---|
1019 | } else {
|
---|
1020 | /* add segment to tail of unacked list */
|
---|
1021 | useg->next = seg;
|
---|
1022 | useg = useg->next;
|
---|
1023 | }
|
---|
1024 | }
|
---|
1025 | /* do not queue empty segments on the unacked list */
|
---|
1026 | } else {
|
---|
1027 | tcp_seg_free(seg);
|
---|
1028 | }
|
---|
1029 | seg = pcb->unsent;
|
---|
1030 | }
|
---|
1031 | #if TCP_OVERSIZE
|
---|
1032 | if (pcb->unsent == NULL) {
|
---|
1033 | /* last unsent has been removed, reset unsent_oversize */
|
---|
1034 | pcb->unsent_oversize = 0;
|
---|
1035 | }
|
---|
1036 | #endif /* TCP_OVERSIZE */
|
---|
1037 |
|
---|
1038 | pcb->flags &= ~TF_NAGLEMEMERR;
|
---|
1039 | return ERR_OK;
|
---|
1040 | }
|
---|
1041 |
|
---|
1042 | /**
|
---|
1043 | * Called by tcp_output() to actually send a TCP segment over IP.
|
---|
1044 | *
|
---|
1045 | * @param seg the tcp_seg to send
|
---|
1046 | * @param pcb the tcp_pcb for the TCP connection used to send the segment
|
---|
1047 | */
|
---|
1048 | static void
|
---|
1049 | tcp_output_segment(struct tcp_seg *seg, struct tcp_pcb *pcb)
|
---|
1050 | {
|
---|
1051 | u16_t len;
|
---|
1052 | struct netif *netif;
|
---|
1053 | u32_t *opts;
|
---|
1054 |
|
---|
1055 | /** @bug Exclude retransmitted segments from this count. */
|
---|
1056 | snmp_inc_tcpoutsegs();
|
---|
1057 |
|
---|
1058 | /* The TCP header has already been constructed, but the ackno and
|
---|
1059 | wnd fields remain. */
|
---|
1060 | seg->tcphdr->ackno = htonl(pcb->rcv_nxt);
|
---|
1061 |
|
---|
1062 | /* advertise our receive window size in this TCP segment */
|
---|
1063 | seg->tcphdr->wnd = htons(pcb->rcv_ann_wnd);
|
---|
1064 |
|
---|
1065 | pcb->rcv_ann_right_edge = pcb->rcv_nxt + pcb->rcv_ann_wnd;
|
---|
1066 |
|
---|
1067 | /* Add any requested options. NB MSS option is only set on SYN
|
---|
1068 | packets, so ignore it here */
|
---|
1069 | opts = (u32_t *)(void *)(seg->tcphdr + 1);
|
---|
1070 | if (seg->flags & TF_SEG_OPTS_MSS) {
|
---|
1071 | u16_t mss;
|
---|
1072 | #if TCP_CALCULATE_EFF_SEND_MSS
|
---|
1073 | mss = tcp_eff_send_mss(TCP_MSS, &pcb->remote_ip);
|
---|
1074 | #else /* TCP_CALCULATE_EFF_SEND_MSS */
|
---|
1075 | mss = TCP_MSS;
|
---|
1076 | #endif /* TCP_CALCULATE_EFF_SEND_MSS */
|
---|
1077 | *opts = TCP_BUILD_MSS_OPTION(mss);
|
---|
1078 | opts += 1;
|
---|
1079 | }
|
---|
1080 | #if LWIP_TCP_TIMESTAMPS
|
---|
1081 | pcb->ts_lastacksent = pcb->rcv_nxt;
|
---|
1082 |
|
---|
1083 | if (seg->flags & TF_SEG_OPTS_TS) {
|
---|
1084 | tcp_build_timestamp_option(pcb, opts);
|
---|
1085 | opts += 3;
|
---|
1086 | }
|
---|
1087 | #endif
|
---|
1088 |
|
---|
1089 | /* Set retransmission timer running if it is not currently enabled
|
---|
1090 | This must be set before checking the route. */
|
---|
1091 | if (pcb->rtime == -1) {
|
---|
1092 | pcb->rtime = 0;
|
---|
1093 | }
|
---|
1094 |
|
---|
1095 | /* If we don't have a local IP address, we get one by
|
---|
1096 | calling ip_route(). */
|
---|
1097 | if (ip_addr_isany(&(pcb->local_ip))) {
|
---|
1098 | netif = ip_route(&(pcb->remote_ip));
|
---|
1099 | if (netif == NULL) {
|
---|
1100 | return;
|
---|
1101 | }
|
---|
1102 | ip_addr_copy(pcb->local_ip, netif->ip_addr);
|
---|
1103 | }
|
---|
1104 |
|
---|
1105 | if (pcb->rttest == 0) {
|
---|
1106 | pcb->rttest = tcp_ticks;
|
---|
1107 | pcb->rtseq = ntohl(seg->tcphdr->seqno);
|
---|
1108 |
|
---|
1109 | LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_output_segment: rtseq %"U32_F"\n", pcb->rtseq));
|
---|
1110 | }
|
---|
1111 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output_segment: %"U32_F":%"U32_F"\n",
|
---|
1112 | htonl(seg->tcphdr->seqno), htonl(seg->tcphdr->seqno) +
|
---|
1113 | seg->len));
|
---|
1114 |
|
---|
1115 | len = (u16_t)((u8_t *)seg->tcphdr - (u8_t *)seg->p->payload);
|
---|
1116 |
|
---|
1117 | seg->p->len -= len;
|
---|
1118 | seg->p->tot_len -= len;
|
---|
1119 |
|
---|
1120 | seg->p->payload = seg->tcphdr;
|
---|
1121 |
|
---|
1122 | seg->tcphdr->chksum = 0;
|
---|
1123 | #if CHECKSUM_GEN_TCP
|
---|
1124 | #if TCP_CHECKSUM_ON_COPY
|
---|
1125 | {
|
---|
1126 | u32_t acc;
|
---|
1127 | #if TCP_CHECKSUM_ON_COPY_SANITY_CHECK
|
---|
1128 | u16_t chksum_slow = inet_chksum_pseudo(seg->p, &(pcb->local_ip),
|
---|
1129 | &(pcb->remote_ip),
|
---|
1130 | IP_PROTO_TCP, seg->p->tot_len);
|
---|
1131 | #endif /* TCP_CHECKSUM_ON_COPY_SANITY_CHECK */
|
---|
1132 | if ((seg->flags & TF_SEG_DATA_CHECKSUMMED) == 0) {
|
---|
1133 | LWIP_ASSERT("data included but not checksummed",
|
---|
1134 | seg->p->tot_len == (TCPH_HDRLEN(seg->tcphdr) * 4));
|
---|
1135 | }
|
---|
1136 |
|
---|
1137 | /* rebuild TCP header checksum (TCP header changes for retransmissions!) */
|
---|
1138 | acc = inet_chksum_pseudo_partial(seg->p, &(pcb->local_ip),
|
---|
1139 | &(pcb->remote_ip),
|
---|
1140 | IP_PROTO_TCP, seg->p->tot_len, TCPH_HDRLEN(seg->tcphdr) * 4);
|
---|
1141 | /* add payload checksum */
|
---|
1142 | if (seg->chksum_swapped) {
|
---|
1143 | seg->chksum = SWAP_BYTES_IN_WORD(seg->chksum);
|
---|
1144 | seg->chksum_swapped = 0;
|
---|
1145 | }
|
---|
1146 | acc += (u16_t)~(seg->chksum);
|
---|
1147 | seg->tcphdr->chksum = FOLD_U32T(acc);
|
---|
1148 | #if TCP_CHECKSUM_ON_COPY_SANITY_CHECK
|
---|
1149 | if (chksum_slow != seg->tcphdr->chksum) {
|
---|
1150 | LWIP_DEBUGF(TCP_DEBUG | LWIP_DBG_LEVEL_WARNING,
|
---|
1151 | ("tcp_output_segment: calculated checksum is %"X16_F" instead of %"X16_F"\n",
|
---|
1152 | seg->tcphdr->chksum, chksum_slow));
|
---|
1153 | seg->tcphdr->chksum = chksum_slow;
|
---|
1154 | }
|
---|
1155 | #endif /* TCP_CHECKSUM_ON_COPY_SANITY_CHECK */
|
---|
1156 | }
|
---|
1157 | #else /* TCP_CHECKSUM_ON_COPY */
|
---|
1158 | seg->tcphdr->chksum = inet_chksum_pseudo(seg->p, &(pcb->local_ip),
|
---|
1159 | &(pcb->remote_ip),
|
---|
1160 | IP_PROTO_TCP, seg->p->tot_len);
|
---|
1161 | #endif /* TCP_CHECKSUM_ON_COPY */
|
---|
1162 | #endif /* CHECKSUM_GEN_TCP */
|
---|
1163 | TCP_STATS_INC(tcp.xmit);
|
---|
1164 |
|
---|
1165 | #if LWIP_NETIF_HWADDRHINT
|
---|
1166 | ip_output_hinted(seg->p, &(pcb->local_ip), &(pcb->remote_ip), pcb->ttl, pcb->tos,
|
---|
1167 | IP_PROTO_TCP, &(pcb->addr_hint));
|
---|
1168 | #else /* LWIP_NETIF_HWADDRHINT*/
|
---|
1169 | ip_output(seg->p, &(pcb->local_ip), &(pcb->remote_ip), pcb->ttl, pcb->tos,
|
---|
1170 | IP_PROTO_TCP);
|
---|
1171 | #endif /* LWIP_NETIF_HWADDRHINT*/
|
---|
1172 | }
|
---|
1173 |
|
---|
1174 | /**
|
---|
1175 | * Send a TCP RESET packet (empty segment with RST flag set) either to
|
---|
1176 | * abort a connection or to show that there is no matching local connection
|
---|
1177 | * for a received segment.
|
---|
1178 | *
|
---|
1179 | * Called by tcp_abort() (to abort a local connection), tcp_input() (if no
|
---|
1180 | * matching local pcb was found), tcp_listen_input() (if incoming segment
|
---|
1181 | * has ACK flag set) and tcp_process() (received segment in the wrong state)
|
---|
1182 | *
|
---|
1183 | * Since a RST segment is in most cases not sent for an active connection,
|
---|
1184 | * tcp_rst() has a number of arguments that are taken from a tcp_pcb for
|
---|
1185 | * most other segment output functions.
|
---|
1186 | *
|
---|
1187 | * @param seqno the sequence number to use for the outgoing segment
|
---|
1188 | * @param ackno the acknowledge number to use for the outgoing segment
|
---|
1189 | * @param local_ip the local IP address to send the segment from
|
---|
1190 | * @param remote_ip the remote IP address to send the segment to
|
---|
1191 | * @param local_port the local TCP port to send the segment from
|
---|
1192 | * @param remote_port the remote TCP port to send the segment to
|
---|
1193 | */
|
---|
1194 | void
|
---|
1195 | tcp_rst(u32_t seqno, u32_t ackno,
|
---|
1196 | ip_addr_t *local_ip, ip_addr_t *remote_ip,
|
---|
1197 | u16_t local_port, u16_t remote_port)
|
---|
1198 | {
|
---|
1199 | struct pbuf *p;
|
---|
1200 | struct tcp_hdr *tcphdr;
|
---|
1201 | p = pbuf_alloc(PBUF_IP, TCP_HLEN, PBUF_RAM);
|
---|
1202 | if (p == NULL) {
|
---|
1203 | LWIP_DEBUGF(TCP_DEBUG, ("tcp_rst: could not allocate memory for pbuf\n"));
|
---|
1204 | return;
|
---|
1205 | }
|
---|
1206 | LWIP_ASSERT("check that first pbuf can hold struct tcp_hdr",
|
---|
1207 | (p->len >= sizeof(struct tcp_hdr)));
|
---|
1208 |
|
---|
1209 | tcphdr = (struct tcp_hdr *)p->payload;
|
---|
1210 | tcphdr->src = htons(local_port);
|
---|
1211 | tcphdr->dest = htons(remote_port);
|
---|
1212 | tcphdr->seqno = htonl(seqno);
|
---|
1213 | tcphdr->ackno = htonl(ackno);
|
---|
1214 | TCPH_HDRLEN_FLAGS_SET(tcphdr, TCP_HLEN/4, TCP_RST | TCP_ACK);
|
---|
1215 | tcphdr->wnd = PP_HTONS(TCP_WND);
|
---|
1216 | tcphdr->chksum = 0;
|
---|
1217 | tcphdr->urgp = 0;
|
---|
1218 |
|
---|
1219 | #if CHECKSUM_GEN_TCP
|
---|
1220 | tcphdr->chksum = inet_chksum_pseudo(p, local_ip, remote_ip,
|
---|
1221 | IP_PROTO_TCP, p->tot_len);
|
---|
1222 | #endif
|
---|
1223 | TCP_STATS_INC(tcp.xmit);
|
---|
1224 | snmp_inc_tcpoutrsts();
|
---|
1225 | /* Send output with hardcoded TTL since we have no access to the pcb */
|
---|
1226 | ip_output(p, local_ip, remote_ip, TCP_TTL, 0, IP_PROTO_TCP);
|
---|
1227 | pbuf_free(p);
|
---|
1228 | LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_rst: seqno %"U32_F" ackno %"U32_F".\n", seqno, ackno));
|
---|
1229 | }
|
---|
1230 |
|
---|
1231 | /**
|
---|
1232 | * Requeue all unacked segments for retransmission
|
---|
1233 | *
|
---|
1234 | * Called by tcp_slowtmr() for slow retransmission.
|
---|
1235 | *
|
---|
1236 | * @param pcb the tcp_pcb for which to re-enqueue all unacked segments
|
---|
1237 | */
|
---|
1238 | void
|
---|
1239 | tcp_rexmit_rto(struct tcp_pcb *pcb)
|
---|
1240 | {
|
---|
1241 | struct tcp_seg *seg;
|
---|
1242 |
|
---|
1243 | if (pcb->unacked == NULL) {
|
---|
1244 | return;
|
---|
1245 | }
|
---|
1246 |
|
---|
1247 | /* Move all unacked segments to the head of the unsent queue */
|
---|
1248 | for (seg = pcb->unacked; seg->next != NULL; seg = seg->next);
|
---|
1249 | /* concatenate unsent queue after unacked queue */
|
---|
1250 | seg->next = pcb->unsent;
|
---|
1251 | /* unsent queue is the concatenated queue (of unacked, unsent) */
|
---|
1252 | pcb->unsent = pcb->unacked;
|
---|
1253 | /* unacked queue is now empty */
|
---|
1254 | pcb->unacked = NULL;
|
---|
1255 | /* last unsent hasn't changed, no need to reset unsent_oversize */
|
---|
1256 |
|
---|
1257 | /* increment number of retransmissions */
|
---|
1258 | ++pcb->nrtx;
|
---|
1259 |
|
---|
1260 | /* Don't take any RTT measurements after retransmitting. */
|
---|
1261 | pcb->rttest = 0;
|
---|
1262 |
|
---|
1263 | /* Do the actual retransmission */
|
---|
1264 | tcp_output(pcb);
|
---|
1265 | }
|
---|
1266 |
|
---|
1267 | /**
|
---|
1268 | * Requeue the first unacked segment for retransmission
|
---|
1269 | *
|
---|
1270 | * Called by tcp_receive() for fast retramsmit.
|
---|
1271 | *
|
---|
1272 | * @param pcb the tcp_pcb for which to retransmit the first unacked segment
|
---|
1273 | */
|
---|
1274 | void
|
---|
1275 | tcp_rexmit(struct tcp_pcb *pcb)
|
---|
1276 | {
|
---|
1277 | struct tcp_seg *seg;
|
---|
1278 | struct tcp_seg **cur_seg;
|
---|
1279 |
|
---|
1280 | if (pcb->unacked == NULL) {
|
---|
1281 | return;
|
---|
1282 | }
|
---|
1283 |
|
---|
1284 | /* Move the first unacked segment to the unsent queue */
|
---|
1285 | /* Keep the unsent queue sorted. */
|
---|
1286 | seg = pcb->unacked;
|
---|
1287 | pcb->unacked = seg->next;
|
---|
1288 |
|
---|
1289 | cur_seg = &(pcb->unsent);
|
---|
1290 | while (*cur_seg &&
|
---|
1291 | TCP_SEQ_LT(ntohl((*cur_seg)->tcphdr->seqno), ntohl(seg->tcphdr->seqno))) {
|
---|
1292 | cur_seg = &((*cur_seg)->next );
|
---|
1293 | }
|
---|
1294 | seg->next = *cur_seg;
|
---|
1295 | *cur_seg = seg;
|
---|
1296 | #if TCP_OVERSIZE
|
---|
1297 | if (seg->next == NULL) {
|
---|
1298 | /* the retransmitted segment is last in unsent, so reset unsent_oversize */
|
---|
1299 | pcb->unsent_oversize = 0;
|
---|
1300 | }
|
---|
1301 | #endif /* TCP_OVERSIZE */
|
---|
1302 |
|
---|
1303 | ++pcb->nrtx;
|
---|
1304 |
|
---|
1305 | /* Don't take any rtt measurements after retransmitting. */
|
---|
1306 | pcb->rttest = 0;
|
---|
1307 |
|
---|
1308 | /* Do the actual retransmission. */
|
---|
1309 | snmp_inc_tcpretranssegs();
|
---|
1310 | /* No need to call tcp_output: we are always called from tcp_input()
|
---|
1311 | and thus tcp_output directly returns. */
|
---|
1312 | }
|
---|
1313 |
|
---|
1314 |
|
---|
1315 | /**
|
---|
1316 | * Handle retransmission after three dupacks received
|
---|
1317 | *
|
---|
1318 | * @param pcb the tcp_pcb for which to retransmit the first unacked segment
|
---|
1319 | */
|
---|
1320 | void
|
---|
1321 | tcp_rexmit_fast(struct tcp_pcb *pcb)
|
---|
1322 | {
|
---|
1323 | if (pcb->unacked != NULL && !(pcb->flags & TF_INFR)) {
|
---|
1324 | /* This is fast retransmit. Retransmit the first unacked segment. */
|
---|
1325 | LWIP_DEBUGF(TCP_FR_DEBUG,
|
---|
1326 | ("tcp_receive: dupacks %"U16_F" (%"U32_F
|
---|
1327 | "), fast retransmit %"U32_F"\n",
|
---|
1328 | (u16_t)pcb->dupacks, pcb->lastack,
|
---|
1329 | ntohl(pcb->unacked->tcphdr->seqno)));
|
---|
1330 | tcp_rexmit(pcb);
|
---|
1331 |
|
---|
1332 | /* Set ssthresh to half of the minimum of the current
|
---|
1333 | * cwnd and the advertised window */
|
---|
1334 | if (pcb->cwnd > pcb->snd_wnd) {
|
---|
1335 | pcb->ssthresh = pcb->snd_wnd / 2;
|
---|
1336 | } else {
|
---|
1337 | pcb->ssthresh = pcb->cwnd / 2;
|
---|
1338 | }
|
---|
1339 |
|
---|
1340 | /* The minimum value for ssthresh should be 2 MSS */
|
---|
1341 | if (pcb->ssthresh < 2*pcb->mss) {
|
---|
1342 | LWIP_DEBUGF(TCP_FR_DEBUG,
|
---|
1343 | ("tcp_receive: The minimum value for ssthresh %"U16_F
|
---|
1344 | " should be min 2 mss %"U16_F"...\n",
|
---|
1345 | pcb->ssthresh, 2*pcb->mss));
|
---|
1346 | pcb->ssthresh = 2*pcb->mss;
|
---|
1347 | }
|
---|
1348 |
|
---|
1349 | pcb->cwnd = pcb->ssthresh + 3 * pcb->mss;
|
---|
1350 | pcb->flags |= TF_INFR;
|
---|
1351 | }
|
---|
1352 | }
|
---|
1353 |
|
---|
1354 |
|
---|
1355 | /**
|
---|
1356 | * Send keepalive packets to keep a connection active although
|
---|
1357 | * no data is sent over it.
|
---|
1358 | *
|
---|
1359 | * Called by tcp_slowtmr()
|
---|
1360 | *
|
---|
1361 | * @param pcb the tcp_pcb for which to send a keepalive packet
|
---|
1362 | */
|
---|
1363 | void
|
---|
1364 | tcp_keepalive(struct tcp_pcb *pcb)
|
---|
1365 | {
|
---|
1366 | struct pbuf *p;
|
---|
1367 | struct tcp_hdr *tcphdr;
|
---|
1368 |
|
---|
1369 | LWIP_DEBUGF(TCP_DEBUG, ("tcp_keepalive: sending KEEPALIVE probe to %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
|
---|
1370 | ip4_addr1_16(&pcb->remote_ip), ip4_addr2_16(&pcb->remote_ip),
|
---|
1371 | ip4_addr3_16(&pcb->remote_ip), ip4_addr4_16(&pcb->remote_ip)));
|
---|
1372 |
|
---|
1373 | LWIP_DEBUGF(TCP_DEBUG, ("tcp_keepalive: tcp_ticks %"U32_F" pcb->tmr %"U32_F" pcb->keep_cnt_sent %"U16_F"\n",
|
---|
1374 | tcp_ticks, pcb->tmr, pcb->keep_cnt_sent));
|
---|
1375 |
|
---|
1376 | p = tcp_output_alloc_header(pcb, 0, 0, htonl(pcb->snd_nxt - 1));
|
---|
1377 | if(p == NULL) {
|
---|
1378 | LWIP_DEBUGF(TCP_DEBUG,
|
---|
1379 | ("tcp_keepalive: could not allocate memory for pbuf\n"));
|
---|
1380 | return;
|
---|
1381 | }
|
---|
1382 | tcphdr = (struct tcp_hdr *)p->payload;
|
---|
1383 |
|
---|
1384 | #if CHECKSUM_GEN_TCP
|
---|
1385 | tcphdr->chksum = inet_chksum_pseudo(p, &pcb->local_ip, &pcb->remote_ip,
|
---|
1386 | IP_PROTO_TCP, p->tot_len);
|
---|
1387 | #endif
|
---|
1388 | TCP_STATS_INC(tcp.xmit);
|
---|
1389 |
|
---|
1390 | /* Send output to IP */
|
---|
1391 | #if LWIP_NETIF_HWADDRHINT
|
---|
1392 | ip_output_hinted(p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl, 0, IP_PROTO_TCP,
|
---|
1393 | &(pcb->addr_hint));
|
---|
1394 | #else /* LWIP_NETIF_HWADDRHINT*/
|
---|
1395 | ip_output(p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl, 0, IP_PROTO_TCP);
|
---|
1396 | #endif /* LWIP_NETIF_HWADDRHINT*/
|
---|
1397 |
|
---|
1398 | pbuf_free(p);
|
---|
1399 |
|
---|
1400 | LWIP_DEBUGF(TCP_DEBUG, ("tcp_keepalive: seqno %"U32_F" ackno %"U32_F".\n",
|
---|
1401 | pcb->snd_nxt - 1, pcb->rcv_nxt));
|
---|
1402 | }
|
---|
1403 |
|
---|
1404 |
|
---|
1405 | /**
|
---|
1406 | * Send persist timer zero-window probes to keep a connection active
|
---|
1407 | * when a window update is lost.
|
---|
1408 | *
|
---|
1409 | * Called by tcp_slowtmr()
|
---|
1410 | *
|
---|
1411 | * @param pcb the tcp_pcb for which to send a zero-window probe packet
|
---|
1412 | */
|
---|
1413 | void
|
---|
1414 | tcp_zero_window_probe(struct tcp_pcb *pcb)
|
---|
1415 | {
|
---|
1416 | struct pbuf *p;
|
---|
1417 | struct tcp_hdr *tcphdr;
|
---|
1418 | struct tcp_seg *seg;
|
---|
1419 | u16_t len;
|
---|
1420 | u8_t is_fin;
|
---|
1421 |
|
---|
1422 | LWIP_DEBUGF(TCP_DEBUG,
|
---|
1423 | ("tcp_zero_window_probe: sending ZERO WINDOW probe to %"
|
---|
1424 | U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
|
---|
1425 | ip4_addr1_16(&pcb->remote_ip), ip4_addr2_16(&pcb->remote_ip),
|
---|
1426 | ip4_addr3_16(&pcb->remote_ip), ip4_addr4_16(&pcb->remote_ip)));
|
---|
1427 |
|
---|
1428 | LWIP_DEBUGF(TCP_DEBUG,
|
---|
1429 | ("tcp_zero_window_probe: tcp_ticks %"U32_F
|
---|
1430 | " pcb->tmr %"U32_F" pcb->keep_cnt_sent %"U16_F"\n",
|
---|
1431 | tcp_ticks, pcb->tmr, pcb->keep_cnt_sent));
|
---|
1432 |
|
---|
1433 | seg = pcb->unacked;
|
---|
1434 |
|
---|
1435 | if(seg == NULL) {
|
---|
1436 | seg = pcb->unsent;
|
---|
1437 | }
|
---|
1438 | if(seg == NULL) {
|
---|
1439 | return;
|
---|
1440 | }
|
---|
1441 |
|
---|
1442 | is_fin = ((TCPH_FLAGS(seg->tcphdr) & TCP_FIN) != 0) && (seg->len == 0);
|
---|
1443 | /* we want to send one seqno: either FIN or data (no options) */
|
---|
1444 | len = is_fin ? 0 : 1;
|
---|
1445 |
|
---|
1446 | p = tcp_output_alloc_header(pcb, 0, len, seg->tcphdr->seqno);
|
---|
1447 | if(p == NULL) {
|
---|
1448 | LWIP_DEBUGF(TCP_DEBUG, ("tcp_zero_window_probe: no memory for pbuf\n"));
|
---|
1449 | return;
|
---|
1450 | }
|
---|
1451 | tcphdr = (struct tcp_hdr *)p->payload;
|
---|
1452 |
|
---|
1453 | if (is_fin) {
|
---|
1454 | /* FIN segment, no data */
|
---|
1455 | TCPH_FLAGS_SET(tcphdr, TCP_ACK | TCP_FIN);
|
---|
1456 | } else {
|
---|
1457 | /* Data segment, copy in one byte from the head of the unacked queue */
|
---|
1458 | char *d = ((char *)p->payload + TCP_HLEN);
|
---|
1459 | /* Depending on whether the segment has already been sent (unacked) or not
|
---|
1460 | (unsent), seg->p->payload points to the IP header or TCP header.
|
---|
1461 | Ensure we copy the first TCP data byte: */
|
---|
1462 | pbuf_copy_partial(seg->p, d, 1, seg->p->tot_len - seg->len);
|
---|
1463 | }
|
---|
1464 |
|
---|
1465 | #if CHECKSUM_GEN_TCP
|
---|
1466 | tcphdr->chksum = inet_chksum_pseudo(p, &pcb->local_ip, &pcb->remote_ip,
|
---|
1467 | IP_PROTO_TCP, p->tot_len);
|
---|
1468 | #endif
|
---|
1469 | TCP_STATS_INC(tcp.xmit);
|
---|
1470 |
|
---|
1471 | /* Send output to IP */
|
---|
1472 | #if LWIP_NETIF_HWADDRHINT
|
---|
1473 | ip_output_hinted(p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl, 0, IP_PROTO_TCP,
|
---|
1474 | &(pcb->addr_hint));
|
---|
1475 | #else /* LWIP_NETIF_HWADDRHINT*/
|
---|
1476 | ip_output(p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl, 0, IP_PROTO_TCP);
|
---|
1477 | #endif /* LWIP_NETIF_HWADDRHINT*/
|
---|
1478 |
|
---|
1479 | pbuf_free(p);
|
---|
1480 |
|
---|
1481 | LWIP_DEBUGF(TCP_DEBUG, ("tcp_zero_window_probe: seqno %"U32_F
|
---|
1482 | " ackno %"U32_F".\n",
|
---|
1483 | pcb->snd_nxt - 1, pcb->rcv_nxt));
|
---|
1484 | }
|
---|
1485 | #endif /* LWIP_TCP */
|
---|