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 | * There are two distinct ways for TCP segments to get sent:
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8 | * - queued data: these are segments transferring data or segments containing
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9 | * SYN or FIN (which both count as one sequence number). They are created as
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10 | * struct @ref pbuf together with a struct tcp_seg and enqueue to the
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11 | * unsent list of the pcb. They are sent by tcp_output:
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12 | * - @ref tcp_write : creates data segments
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13 | * - @ref tcp_split_unsent_seg : splits a data segment
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14 | * - @ref tcp_enqueue_flags : creates SYN-only or FIN-only segments
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15 | * - @ref tcp_output / tcp_output_segment : finalize the tcp header
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16 | * (e.g. sequence numbers, options, checksum) and output to IP
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17 | * - the various tcp_rexmit functions shuffle around segments between the
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18 | * unsent an unacked lists to retransmit them
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19 | * - tcp_create_segment and tcp_pbuf_prealloc allocate pbuf and
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20 | * segment for these functions
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21 | * - direct send: these segments don't contain data but control the connection
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22 | * behaviour. They are created as pbuf only and sent directly without
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23 | * enqueueing them:
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24 | * - @ref tcp_send_empty_ack sends an ACK-only segment
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25 | * - @ref tcp_rst sends a RST segment
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26 | * - @ref tcp_keepalive sends a keepalive segment
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27 | * - @ref tcp_zero_window_probe sends a window probe segment
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28 | * - tcp_output_alloc_header allocates a header-only pbuf for these functions
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29 | */
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30 |
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31 | /*
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32 | * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
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33 | * All rights reserved.
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34 | *
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35 | * Redistribution and use in source and binary forms, with or without modification,
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36 | * are permitted provided that the following conditions are met:
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37 | *
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38 | * 1. Redistributions of source code must retain the above copyright notice,
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39 | * this list of conditions and the following disclaimer.
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40 | * 2. Redistributions in binary form must reproduce the above copyright notice,
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41 | * this list of conditions and the following disclaimer in the documentation
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42 | * and/or other materials provided with the distribution.
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43 | * 3. The name of the author may not be used to endorse or promote products
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44 | * derived from this software without specific prior written permission.
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45 | *
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46 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
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47 | * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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48 | * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
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49 | * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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50 | * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
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51 | * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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52 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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53 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
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54 | * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
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55 | * OF SUCH DAMAGE.
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56 | *
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57 | * This file is part of the lwIP TCP/IP stack.
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58 | *
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59 | * Author: Adam Dunkels <adam@sics.se>
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60 | *
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61 | */
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62 |
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63 | #include "lwip/opt.h"
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64 |
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65 | #if LWIP_TCP /* don't build if not configured for use in lwipopts.h */
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66 |
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67 | #include "lwip/priv/tcp_priv.h"
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68 | #include "lwip/def.h"
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69 | #include "lwip/mem.h"
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70 | #include "lwip/memp.h"
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71 | #include "lwip/ip_addr.h"
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72 | #include "lwip/netif.h"
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73 | #include "lwip/inet_chksum.h"
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74 | #include "lwip/stats.h"
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75 | #include "lwip/ip6.h"
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76 | #include "lwip/ip6_addr.h"
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77 | #if LWIP_TCP_TIMESTAMPS
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78 | #include "lwip/sys.h"
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79 | #endif
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80 |
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81 | #include <string.h>
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82 |
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83 | #ifdef LWIP_HOOK_FILENAME
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84 | #include LWIP_HOOK_FILENAME
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85 | #endif
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86 |
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87 | /* Allow to add custom TCP header options by defining this hook */
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88 | #ifdef LWIP_HOOK_TCP_OUT_TCPOPT_LENGTH
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89 | #define LWIP_TCP_OPT_LENGTH_SEGMENT(flags, pcb) LWIP_HOOK_TCP_OUT_TCPOPT_LENGTH(pcb, LWIP_TCP_OPT_LENGTH(flags))
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90 | #else
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91 | #define LWIP_TCP_OPT_LENGTH_SEGMENT(flags, pcb) LWIP_TCP_OPT_LENGTH(flags)
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92 | #endif
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93 |
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94 | /* Define some copy-macros for checksum-on-copy so that the code looks
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95 | nicer by preventing too many ifdef's. */
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96 | #if TCP_CHECKSUM_ON_COPY
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97 | #define TCP_DATA_COPY(dst, src, len, seg) do { \
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98 | tcp_seg_add_chksum(LWIP_CHKSUM_COPY(dst, src, len), \
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99 | len, &seg->chksum, &seg->chksum_swapped); \
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100 | seg->flags |= TF_SEG_DATA_CHECKSUMMED; } while(0)
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101 | #define TCP_DATA_COPY2(dst, src, len, chksum, chksum_swapped) \
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102 | tcp_seg_add_chksum(LWIP_CHKSUM_COPY(dst, src, len), len, chksum, chksum_swapped);
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103 | #else /* TCP_CHECKSUM_ON_COPY*/
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104 | #define TCP_DATA_COPY(dst, src, len, seg) MEMCPY(dst, src, len)
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105 | #define TCP_DATA_COPY2(dst, src, len, chksum, chksum_swapped) MEMCPY(dst, src, len)
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106 | #endif /* TCP_CHECKSUM_ON_COPY*/
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107 |
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108 | /** Define this to 1 for an extra check that the output checksum is valid
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109 | * (usefule when the checksum is generated by the application, not the stack) */
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110 | #ifndef TCP_CHECKSUM_ON_COPY_SANITY_CHECK
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111 | #define TCP_CHECKSUM_ON_COPY_SANITY_CHECK 0
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112 | #endif
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113 | /* Allow to override the failure of sanity check from warning to e.g. hard failure */
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114 | #if TCP_CHECKSUM_ON_COPY_SANITY_CHECK
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115 | #ifndef TCP_CHECKSUM_ON_COPY_SANITY_CHECK_FAIL
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116 | #define TCP_CHECKSUM_ON_COPY_SANITY_CHECK_FAIL(msg) LWIP_DEBUGF(TCP_DEBUG | LWIP_DBG_LEVEL_WARNING, msg)
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117 | #endif
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118 | #endif
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119 |
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120 | #if TCP_OVERSIZE
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121 | /** The size of segment pbufs created when TCP_OVERSIZE is enabled */
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122 | #ifndef TCP_OVERSIZE_CALC_LENGTH
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123 | #define TCP_OVERSIZE_CALC_LENGTH(length) ((length) + TCP_OVERSIZE)
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124 | #endif
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125 | #endif
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126 |
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127 | /* Forward declarations.*/
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128 | static err_t tcp_output_segment(struct tcp_seg *seg, struct tcp_pcb *pcb, struct netif *netif);
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129 |
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130 | /* tcp_route: common code that returns a fixed bound netif or calls ip_route */
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131 | static struct netif *
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132 | tcp_route(const struct tcp_pcb *pcb, const ip_addr_t *src, const ip_addr_t *dst)
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133 | {
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134 | LWIP_UNUSED_ARG(src); /* in case IPv4-only and source-based routing is disabled */
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135 |
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136 | if ((pcb != NULL) && (pcb->netif_idx != NETIF_NO_INDEX)) {
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137 | return netif_get_by_index(pcb->netif_idx);
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138 | } else {
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139 | return ip_route(src, dst);
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140 | }
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141 | }
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142 |
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143 | /**
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144 | * Create a TCP segment with prefilled header.
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145 | *
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146 | * Called by @ref tcp_write, @ref tcp_enqueue_flags and @ref tcp_split_unsent_seg
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147 | *
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148 | * @param pcb Protocol control block for the TCP connection.
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149 | * @param p pbuf that is used to hold the TCP header.
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150 | * @param hdrflags TCP flags for header.
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151 | * @param seqno TCP sequence number of this packet
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152 | * @param optflags options to include in TCP header
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153 | * @return a new tcp_seg pointing to p, or NULL.
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154 | * The TCP header is filled in except ackno and wnd.
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155 | * p is freed on failure.
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156 | */
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157 | static struct tcp_seg *
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158 | tcp_create_segment(const struct tcp_pcb *pcb, struct pbuf *p, u8_t hdrflags, u32_t seqno, u8_t optflags)
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159 | {
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160 | struct tcp_seg *seg;
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161 | u8_t optlen;
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162 |
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163 | LWIP_ASSERT("tcp_create_segment: invalid pcb", pcb != NULL);
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164 | LWIP_ASSERT("tcp_create_segment: invalid pbuf", p != NULL);
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165 |
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166 | optlen = LWIP_TCP_OPT_LENGTH_SEGMENT(optflags, pcb);
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167 |
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168 | if ((seg = (struct tcp_seg *)memp_malloc(MEMP_TCP_SEG)) == NULL) {
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169 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("tcp_create_segment: no memory.\n"));
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170 | pbuf_free(p);
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171 | return NULL;
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172 | }
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173 | seg->flags = optflags;
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174 | seg->next = NULL;
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175 | seg->p = p;
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176 | LWIP_ASSERT("p->tot_len >= optlen", p->tot_len >= optlen);
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177 | seg->len = p->tot_len - optlen;
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178 | #if TCP_OVERSIZE_DBGCHECK
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179 | seg->oversize_left = 0;
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180 | #endif /* TCP_OVERSIZE_DBGCHECK */
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181 | #if TCP_CHECKSUM_ON_COPY
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182 | seg->chksum = 0;
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183 | seg->chksum_swapped = 0;
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184 | /* check optflags */
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185 | LWIP_ASSERT("invalid optflags passed: TF_SEG_DATA_CHECKSUMMED",
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186 | (optflags & TF_SEG_DATA_CHECKSUMMED) == 0);
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187 | #endif /* TCP_CHECKSUM_ON_COPY */
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188 |
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189 | /* build TCP header */
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190 | if (pbuf_add_header(p, TCP_HLEN)) {
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191 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("tcp_create_segment: no room for TCP header in pbuf.\n"));
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192 | TCP_STATS_INC(tcp.err);
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193 | tcp_seg_free(seg);
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194 | return NULL;
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195 | }
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196 | seg->tcphdr = (struct tcp_hdr *)seg->p->payload;
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197 | seg->tcphdr->src = lwip_htons(pcb->local_port);
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198 | seg->tcphdr->dest = lwip_htons(pcb->remote_port);
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199 | seg->tcphdr->seqno = lwip_htonl(seqno);
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200 | /* ackno is set in tcp_output */
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201 | TCPH_HDRLEN_FLAGS_SET(seg->tcphdr, (5 + optlen / 4), hdrflags);
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202 | /* wnd and chksum are set in tcp_output */
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203 | seg->tcphdr->urgp = 0;
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204 | return seg;
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205 | }
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206 |
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207 | /**
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208 | * Allocate a PBUF_RAM pbuf, perhaps with extra space at the end.
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209 | *
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210 | * This function is like pbuf_alloc(layer, length, PBUF_RAM) except
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211 | * there may be extra bytes available at the end.
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212 | *
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213 | * Called by @ref tcp_write
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214 | *
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215 | * @param layer flag to define header size.
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216 | * @param length size of the pbuf's payload.
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217 | * @param max_length maximum usable size of payload+oversize.
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218 | * @param oversize pointer to a u16_t that will receive the number of usable tail bytes.
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219 | * @param pcb The TCP connection that will enqueue the pbuf.
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220 | * @param apiflags API flags given to tcp_write.
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221 | * @param first_seg true when this pbuf will be used in the first enqueued segment.
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222 | */
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223 | #if TCP_OVERSIZE
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224 | static struct pbuf *
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225 | tcp_pbuf_prealloc(pbuf_layer layer, u16_t length, u16_t max_length,
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226 | u16_t *oversize, const struct tcp_pcb *pcb, u8_t apiflags,
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227 | u8_t first_seg)
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228 | {
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229 | struct pbuf *p;
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230 | u16_t alloc = length;
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231 |
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232 | LWIP_ASSERT("tcp_pbuf_prealloc: invalid oversize", oversize != NULL);
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233 | LWIP_ASSERT("tcp_pbuf_prealloc: invalid pcb", pcb != NULL);
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234 |
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235 | #if LWIP_NETIF_TX_SINGLE_PBUF
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236 | LWIP_UNUSED_ARG(max_length);
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237 | LWIP_UNUSED_ARG(pcb);
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238 | LWIP_UNUSED_ARG(apiflags);
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239 | LWIP_UNUSED_ARG(first_seg);
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240 | alloc = max_length;
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241 | #else /* LWIP_NETIF_TX_SINGLE_PBUF */
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242 | if (length < max_length) {
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243 | /* Should we allocate an oversized pbuf, or just the minimum
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244 | * length required? If tcp_write is going to be called again
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245 | * before this segment is transmitted, we want the oversized
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246 | * buffer. If the segment will be transmitted immediately, we can
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247 | * save memory by allocating only length. We use a simple
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248 | * heuristic based on the following information:
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249 | *
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250 | * Did the user set TCP_WRITE_FLAG_MORE?
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251 | *
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252 | * Will the Nagle algorithm defer transmission of this segment?
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253 | */
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254 | if ((apiflags & TCP_WRITE_FLAG_MORE) ||
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255 | (!(pcb->flags & TF_NODELAY) &&
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256 | (!first_seg ||
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257 | pcb->unsent != NULL ||
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258 | pcb->unacked != NULL))) {
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259 | alloc = LWIP_MIN(max_length, LWIP_MEM_ALIGN_SIZE(TCP_OVERSIZE_CALC_LENGTH(length)));
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260 | }
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261 | }
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262 | #endif /* LWIP_NETIF_TX_SINGLE_PBUF */
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263 | p = pbuf_alloc(layer, alloc, PBUF_RAM);
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264 | if (p == NULL) {
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265 | return NULL;
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266 | }
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267 | LWIP_ASSERT("need unchained pbuf", p->next == NULL);
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268 | *oversize = p->len - length;
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269 | /* trim p->len to the currently used size */
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270 | p->len = p->tot_len = length;
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271 | return p;
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272 | }
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273 | #else /* TCP_OVERSIZE */
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274 | #define tcp_pbuf_prealloc(layer, length, mx, os, pcb, api, fst) pbuf_alloc((layer), (length), PBUF_RAM)
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275 | #endif /* TCP_OVERSIZE */
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276 |
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277 | #if TCP_CHECKSUM_ON_COPY
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278 | /** Add a checksum of newly added data to the segment.
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279 | *
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280 | * Called by tcp_write and tcp_split_unsent_seg.
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281 | */
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282 | static void
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283 | tcp_seg_add_chksum(u16_t chksum, u16_t len, u16_t *seg_chksum,
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284 | u8_t *seg_chksum_swapped)
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285 | {
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286 | u32_t helper;
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287 | /* add chksum to old chksum and fold to u16_t */
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288 | helper = chksum + *seg_chksum;
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289 | chksum = FOLD_U32T(helper);
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290 | if ((len & 1) != 0) {
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291 | *seg_chksum_swapped = 1 - *seg_chksum_swapped;
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292 | chksum = SWAP_BYTES_IN_WORD(chksum);
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293 | }
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294 | *seg_chksum = chksum;
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295 | }
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296 | #endif /* TCP_CHECKSUM_ON_COPY */
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297 |
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298 | /** Checks if tcp_write is allowed or not (checks state, snd_buf and snd_queuelen).
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299 | *
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300 | * @param pcb the tcp pcb to check for
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301 | * @param len length of data to send (checked agains snd_buf)
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302 | * @return ERR_OK if tcp_write is allowed to proceed, another err_t otherwise
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303 | */
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304 | static err_t
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305 | tcp_write_checks(struct tcp_pcb *pcb, u16_t len)
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306 | {
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307 | LWIP_ASSERT("tcp_write_checks: invalid pcb", pcb != NULL);
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308 |
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309 | /* connection is in invalid state for data transmission? */
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310 | if ((pcb->state != ESTABLISHED) &&
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311 | (pcb->state != CLOSE_WAIT) &&
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312 | (pcb->state != SYN_SENT) &&
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313 | (pcb->state != SYN_RCVD)) {
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314 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_STATE | LWIP_DBG_LEVEL_SEVERE, ("tcp_write() called in invalid state\n"));
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315 | return ERR_CONN;
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316 | } else if (len == 0) {
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317 | return ERR_OK;
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318 | }
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319 |
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320 | /* fail on too much data */
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321 | if (len > pcb->snd_buf) {
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322 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_LEVEL_SEVERE, ("tcp_write: too much data (len=%"U16_F" > snd_buf=%"TCPWNDSIZE_F")\n",
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323 | len, pcb->snd_buf));
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324 | tcp_set_flags(pcb, TF_NAGLEMEMERR);
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325 | return ERR_MEM;
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326 | }
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327 |
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328 | LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_write: queuelen: %"TCPWNDSIZE_F"\n", (tcpwnd_size_t)pcb->snd_queuelen));
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329 |
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330 | /* If total number of pbufs on the unsent/unacked queues exceeds the
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331 | * configured maximum, return an error */
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332 | /* check for configured max queuelen and possible overflow */
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333 | if (pcb->snd_queuelen >= LWIP_MIN(TCP_SND_QUEUELEN, (TCP_SNDQUEUELEN_OVERFLOW + 1))) {
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334 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_LEVEL_SEVERE, ("tcp_write: too long queue %"U16_F" (max %"U16_F")\n",
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335 | pcb->snd_queuelen, (u16_t)TCP_SND_QUEUELEN));
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336 | TCP_STATS_INC(tcp.memerr);
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337 | tcp_set_flags(pcb, TF_NAGLEMEMERR);
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338 | return ERR_MEM;
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339 | }
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340 | if (pcb->snd_queuelen != 0) {
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341 | LWIP_ASSERT("tcp_write: pbufs on queue => at least one queue non-empty",
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342 | pcb->unacked != NULL || pcb->unsent != NULL);
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343 | } else {
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344 | LWIP_ASSERT("tcp_write: no pbufs on queue => both queues empty",
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345 | pcb->unacked == NULL && pcb->unsent == NULL);
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346 | }
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347 | return ERR_OK;
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348 | }
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349 |
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350 | /**
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351 | * @ingroup tcp_raw
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352 | * Write data for sending (but does not send it immediately).
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353 | *
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354 | * It waits in the expectation of more data being sent soon (as
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355 | * it can send them more efficiently by combining them together).
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356 | * To prompt the system to send data now, call tcp_output() after
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357 | * calling tcp_write().
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358 | *
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359 | * This function enqueues the data pointed to by the argument dataptr. The length of
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360 | * the data is passed as the len parameter. The apiflags can be one or more of:
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361 | * - TCP_WRITE_FLAG_COPY: indicates whether the new memory should be allocated
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362 | * for the data to be copied into. If this flag is not given, no new memory
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363 | * should be allocated and the data should only be referenced by pointer. This
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364 | * also means that the memory behind dataptr must not change until the data is
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365 | * ACKed by the remote host
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366 | * - TCP_WRITE_FLAG_MORE: indicates that more data follows. If this is omitted,
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367 | * the PSH flag is set in the last segment created by this call to tcp_write.
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368 | * If this flag is given, the PSH flag is not set.
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369 | *
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370 | * The tcp_write() function will fail and return ERR_MEM if the length
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371 | * of the data exceeds the current send buffer size or if the length of
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372 | * the queue of outgoing segment is larger than the upper limit defined
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373 | * in lwipopts.h. The number of bytes available in the output queue can
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374 | * be retrieved with the tcp_sndbuf() function.
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375 | *
|
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376 | * The proper way to use this function is to call the function with at
|
---|
377 | * most tcp_sndbuf() bytes of data. If the function returns ERR_MEM,
|
---|
378 | * the application should wait until some of the currently enqueued
|
---|
379 | * data has been successfully received by the other host and try again.
|
---|
380 | *
|
---|
381 | * @param pcb Protocol control block for the TCP connection to enqueue data for.
|
---|
382 | * @param arg Pointer to the data to be enqueued for sending.
|
---|
383 | * @param len Data length in bytes
|
---|
384 | * @param apiflags combination of following flags :
|
---|
385 | * - TCP_WRITE_FLAG_COPY (0x01) data will be copied into memory belonging to the stack
|
---|
386 | * - TCP_WRITE_FLAG_MORE (0x02) for TCP connection, PSH flag will not be set on last segment sent,
|
---|
387 | * @return ERR_OK if enqueued, another err_t on error
|
---|
388 | */
|
---|
389 | err_t
|
---|
390 | tcp_write(struct tcp_pcb *pcb, const void *arg, u16_t len, u8_t apiflags)
|
---|
391 | {
|
---|
392 | struct pbuf *concat_p = NULL;
|
---|
393 | struct tcp_seg *last_unsent = NULL, *seg = NULL, *prev_seg = NULL, *queue = NULL;
|
---|
394 | u16_t pos = 0; /* position in 'arg' data */
|
---|
395 | u16_t queuelen;
|
---|
396 | u8_t optlen;
|
---|
397 | u8_t optflags = 0;
|
---|
398 | #if TCP_OVERSIZE
|
---|
399 | u16_t oversize = 0;
|
---|
400 | u16_t oversize_used = 0;
|
---|
401 | #if TCP_OVERSIZE_DBGCHECK
|
---|
402 | u16_t oversize_add = 0;
|
---|
403 | #endif /* TCP_OVERSIZE_DBGCHECK*/
|
---|
404 | #endif /* TCP_OVERSIZE */
|
---|
405 | u16_t extendlen = 0;
|
---|
406 | #if TCP_CHECKSUM_ON_COPY
|
---|
407 | u16_t concat_chksum = 0;
|
---|
408 | u8_t concat_chksum_swapped = 0;
|
---|
409 | u16_t concat_chksummed = 0;
|
---|
410 | #endif /* TCP_CHECKSUM_ON_COPY */
|
---|
411 | err_t err;
|
---|
412 | u16_t mss_local;
|
---|
413 |
|
---|
414 | LWIP_ERROR("tcp_write: invalid pcb", pcb != NULL, return ERR_ARG);
|
---|
415 |
|
---|
416 | /* don't allocate segments bigger than half the maximum window we ever received */
|
---|
417 | mss_local = LWIP_MIN(pcb->mss, TCPWND_MIN16(pcb->snd_wnd_max / 2));
|
---|
418 | mss_local = mss_local ? mss_local : pcb->mss;
|
---|
419 |
|
---|
420 | LWIP_ASSERT_CORE_LOCKED();
|
---|
421 |
|
---|
422 | #if LWIP_NETIF_TX_SINGLE_PBUF
|
---|
423 | /* Always copy to try to create single pbufs for TX */
|
---|
424 | apiflags |= TCP_WRITE_FLAG_COPY;
|
---|
425 | #endif /* LWIP_NETIF_TX_SINGLE_PBUF */
|
---|
426 |
|
---|
427 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_write(pcb=%p, data=%p, len=%"U16_F", apiflags=%"U16_F")\n",
|
---|
428 | (void *)pcb, arg, len, (u16_t)apiflags));
|
---|
429 | LWIP_ERROR("tcp_write: arg == NULL (programmer violates API)",
|
---|
430 | arg != NULL, return ERR_ARG;);
|
---|
431 |
|
---|
432 | err = tcp_write_checks(pcb, len);
|
---|
433 | if (err != ERR_OK) {
|
---|
434 | return err;
|
---|
435 | }
|
---|
436 | queuelen = pcb->snd_queuelen;
|
---|
437 |
|
---|
438 | #if LWIP_TCP_TIMESTAMPS
|
---|
439 | if ((pcb->flags & TF_TIMESTAMP)) {
|
---|
440 | /* Make sure the timestamp option is only included in data segments if we
|
---|
441 | agreed about it with the remote host. */
|
---|
442 | optflags = TF_SEG_OPTS_TS;
|
---|
443 | optlen = LWIP_TCP_OPT_LENGTH_SEGMENT(TF_SEG_OPTS_TS, pcb);
|
---|
444 | /* ensure that segments can hold at least one data byte... */
|
---|
445 | mss_local = LWIP_MAX(mss_local, LWIP_TCP_OPT_LEN_TS + 1);
|
---|
446 | } else
|
---|
447 | #endif /* LWIP_TCP_TIMESTAMPS */
|
---|
448 | {
|
---|
449 | optlen = LWIP_TCP_OPT_LENGTH_SEGMENT(0, pcb);
|
---|
450 | }
|
---|
451 |
|
---|
452 |
|
---|
453 | /*
|
---|
454 | * TCP segmentation is done in three phases with increasing complexity:
|
---|
455 | *
|
---|
456 | * 1. Copy data directly into an oversized pbuf.
|
---|
457 | * 2. Chain a new pbuf to the end of pcb->unsent.
|
---|
458 | * 3. Create new segments.
|
---|
459 | *
|
---|
460 | * We may run out of memory at any point. In that case we must
|
---|
461 | * return ERR_MEM and not change anything in pcb. Therefore, all
|
---|
462 | * changes are recorded in local variables and committed at the end
|
---|
463 | * of the function. Some pcb fields are maintained in local copies:
|
---|
464 | *
|
---|
465 | * queuelen = pcb->snd_queuelen
|
---|
466 | * oversize = pcb->unsent_oversize
|
---|
467 | *
|
---|
468 | * These variables are set consistently by the phases:
|
---|
469 | *
|
---|
470 | * seg points to the last segment tampered with.
|
---|
471 | *
|
---|
472 | * pos records progress as data is segmented.
|
---|
473 | */
|
---|
474 |
|
---|
475 | /* Find the tail of the unsent queue. */
|
---|
476 | if (pcb->unsent != NULL) {
|
---|
477 | u16_t space;
|
---|
478 | u16_t unsent_optlen;
|
---|
479 |
|
---|
480 | /* @todo: this could be sped up by keeping last_unsent in the pcb */
|
---|
481 | for (last_unsent = pcb->unsent; last_unsent->next != NULL;
|
---|
482 | last_unsent = last_unsent->next);
|
---|
483 |
|
---|
484 | /* Usable space at the end of the last unsent segment */
|
---|
485 | unsent_optlen = LWIP_TCP_OPT_LENGTH_SEGMENT(last_unsent->flags, pcb);
|
---|
486 | LWIP_ASSERT("mss_local is too small", mss_local >= last_unsent->len + unsent_optlen);
|
---|
487 | space = mss_local - (last_unsent->len + unsent_optlen);
|
---|
488 |
|
---|
489 | /*
|
---|
490 | * Phase 1: Copy data directly into an oversized pbuf.
|
---|
491 | *
|
---|
492 | * The number of bytes copied is recorded in the oversize_used
|
---|
493 | * variable. The actual copying is done at the bottom of the
|
---|
494 | * function.
|
---|
495 | */
|
---|
496 | #if TCP_OVERSIZE
|
---|
497 | #if TCP_OVERSIZE_DBGCHECK
|
---|
498 | /* check that pcb->unsent_oversize matches last_unsent->oversize_left */
|
---|
499 | LWIP_ASSERT("unsent_oversize mismatch (pcb vs. last_unsent)",
|
---|
500 | pcb->unsent_oversize == last_unsent->oversize_left);
|
---|
501 | #endif /* TCP_OVERSIZE_DBGCHECK */
|
---|
502 | oversize = pcb->unsent_oversize;
|
---|
503 | if (oversize > 0) {
|
---|
504 | LWIP_ASSERT("inconsistent oversize vs. space", oversize <= space);
|
---|
505 | seg = last_unsent;
|
---|
506 | oversize_used = LWIP_MIN(space, LWIP_MIN(oversize, len));
|
---|
507 | pos += oversize_used;
|
---|
508 | oversize -= oversize_used;
|
---|
509 | space -= oversize_used;
|
---|
510 | }
|
---|
511 | /* now we are either finished or oversize is zero */
|
---|
512 | LWIP_ASSERT("inconsistent oversize vs. len", (oversize == 0) || (pos == len));
|
---|
513 | #endif /* TCP_OVERSIZE */
|
---|
514 |
|
---|
515 | #if !LWIP_NETIF_TX_SINGLE_PBUF
|
---|
516 | /*
|
---|
517 | * Phase 2: Chain a new pbuf to the end of pcb->unsent.
|
---|
518 | *
|
---|
519 | * As an exception when NOT copying the data, if the given data buffer
|
---|
520 | * directly follows the last unsent data buffer in memory, extend the last
|
---|
521 | * ROM pbuf reference to the buffer, thus saving a ROM pbuf allocation.
|
---|
522 | *
|
---|
523 | * We don't extend segments containing SYN/FIN flags or options
|
---|
524 | * (len==0). The new pbuf is kept in concat_p and pbuf_cat'ed at
|
---|
525 | * the end.
|
---|
526 | *
|
---|
527 | * This phase is skipped for LWIP_NETIF_TX_SINGLE_PBUF as we could only execute
|
---|
528 | * it after rexmit puts a segment from unacked to unsent and at this point,
|
---|
529 | * oversize info is lost.
|
---|
530 | */
|
---|
531 | if ((pos < len) && (space > 0) && (last_unsent->len > 0)) {
|
---|
532 | u16_t seglen = LWIP_MIN(space, len - pos);
|
---|
533 | seg = last_unsent;
|
---|
534 |
|
---|
535 | /* Create a pbuf with a copy or reference to seglen bytes. We
|
---|
536 | * can use PBUF_RAW here since the data appears in the middle of
|
---|
537 | * a segment. A header will never be prepended. */
|
---|
538 | if (apiflags & TCP_WRITE_FLAG_COPY) {
|
---|
539 | /* Data is copied */
|
---|
540 | if ((concat_p = tcp_pbuf_prealloc(PBUF_RAW, seglen, space, &oversize, pcb, apiflags, 1)) == NULL) {
|
---|
541 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_LEVEL_SERIOUS,
|
---|
542 | ("tcp_write : could not allocate memory for pbuf copy size %"U16_F"\n",
|
---|
543 | seglen));
|
---|
544 | goto memerr;
|
---|
545 | }
|
---|
546 | #if TCP_OVERSIZE_DBGCHECK
|
---|
547 | oversize_add = oversize;
|
---|
548 | #endif /* TCP_OVERSIZE_DBGCHECK */
|
---|
549 | TCP_DATA_COPY2(concat_p->payload, (const u8_t *)arg + pos, seglen, &concat_chksum, &concat_chksum_swapped);
|
---|
550 | #if TCP_CHECKSUM_ON_COPY
|
---|
551 | concat_chksummed += seglen;
|
---|
552 | #endif /* TCP_CHECKSUM_ON_COPY */
|
---|
553 | queuelen += pbuf_clen(concat_p);
|
---|
554 | } else {
|
---|
555 | /* Data is not copied */
|
---|
556 | /* If the last unsent pbuf is of type PBUF_ROM, try to extend it. */
|
---|
557 | struct pbuf *p;
|
---|
558 | for (p = last_unsent->p; p->next != NULL; p = p->next);
|
---|
559 | if (((p->type_internal & (PBUF_TYPE_FLAG_STRUCT_DATA_CONTIGUOUS | PBUF_TYPE_FLAG_DATA_VOLATILE)) == 0) &&
|
---|
560 | (const u8_t *)p->payload + p->len == (const u8_t *)arg) {
|
---|
561 | LWIP_ASSERT("tcp_write: ROM pbufs cannot be oversized", pos == 0);
|
---|
562 | extendlen = seglen;
|
---|
563 | } else {
|
---|
564 | if ((concat_p = pbuf_alloc(PBUF_RAW, seglen, PBUF_ROM)) == NULL) {
|
---|
565 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_LEVEL_SERIOUS,
|
---|
566 | ("tcp_write: could not allocate memory for zero-copy pbuf\n"));
|
---|
567 | goto memerr;
|
---|
568 | }
|
---|
569 | /* reference the non-volatile payload data */
|
---|
570 | ((struct pbuf_rom *)concat_p)->payload = (const u8_t *)arg + pos;
|
---|
571 | queuelen += pbuf_clen(concat_p);
|
---|
572 | }
|
---|
573 | #if TCP_CHECKSUM_ON_COPY
|
---|
574 | /* calculate the checksum of nocopy-data */
|
---|
575 | tcp_seg_add_chksum(~inet_chksum((const u8_t *)arg + pos, seglen), seglen,
|
---|
576 | &concat_chksum, &concat_chksum_swapped);
|
---|
577 | concat_chksummed += seglen;
|
---|
578 | #endif /* TCP_CHECKSUM_ON_COPY */
|
---|
579 | }
|
---|
580 |
|
---|
581 | pos += seglen;
|
---|
582 | }
|
---|
583 | #endif /* !LWIP_NETIF_TX_SINGLE_PBUF */
|
---|
584 | } else {
|
---|
585 | #if TCP_OVERSIZE
|
---|
586 | LWIP_ASSERT("unsent_oversize mismatch (pcb->unsent is NULL)",
|
---|
587 | pcb->unsent_oversize == 0);
|
---|
588 | #endif /* TCP_OVERSIZE */
|
---|
589 | }
|
---|
590 |
|
---|
591 | /*
|
---|
592 | * Phase 3: Create new segments.
|
---|
593 | *
|
---|
594 | * The new segments are chained together in the local 'queue'
|
---|
595 | * variable, ready to be appended to pcb->unsent.
|
---|
596 | */
|
---|
597 | while (pos < len) {
|
---|
598 | struct pbuf *p;
|
---|
599 | u16_t left = len - pos;
|
---|
600 | u16_t max_len = mss_local - optlen;
|
---|
601 | u16_t seglen = LWIP_MIN(left, max_len);
|
---|
602 | #if TCP_CHECKSUM_ON_COPY
|
---|
603 | u16_t chksum = 0;
|
---|
604 | u8_t chksum_swapped = 0;
|
---|
605 | #endif /* TCP_CHECKSUM_ON_COPY */
|
---|
606 |
|
---|
607 | if (apiflags & TCP_WRITE_FLAG_COPY) {
|
---|
608 | /* If copy is set, memory should be allocated and data copied
|
---|
609 | * into pbuf */
|
---|
610 | if ((p = tcp_pbuf_prealloc(PBUF_TRANSPORT, seglen + optlen, mss_local, &oversize, pcb, apiflags, queue == NULL)) == NULL) {
|
---|
611 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("tcp_write : could not allocate memory for pbuf copy size %"U16_F"\n", seglen));
|
---|
612 | goto memerr;
|
---|
613 | }
|
---|
614 | LWIP_ASSERT("tcp_write: check that first pbuf can hold the complete seglen",
|
---|
615 | (p->len >= seglen));
|
---|
616 | TCP_DATA_COPY2((char *)p->payload + optlen, (const u8_t *)arg + pos, seglen, &chksum, &chksum_swapped);
|
---|
617 | } else {
|
---|
618 | /* Copy is not set: First allocate a pbuf for holding the data.
|
---|
619 | * Since the referenced data is available at least until it is
|
---|
620 | * sent out on the link (as it has to be ACKed by the remote
|
---|
621 | * party) we can safely use PBUF_ROM instead of PBUF_REF here.
|
---|
622 | */
|
---|
623 | struct pbuf *p2;
|
---|
624 | #if TCP_OVERSIZE
|
---|
625 | LWIP_ASSERT("oversize == 0", oversize == 0);
|
---|
626 | #endif /* TCP_OVERSIZE */
|
---|
627 | if ((p2 = pbuf_alloc(PBUF_TRANSPORT, seglen, PBUF_ROM)) == NULL) {
|
---|
628 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("tcp_write: could not allocate memory for zero-copy pbuf\n"));
|
---|
629 | goto memerr;
|
---|
630 | }
|
---|
631 | #if TCP_CHECKSUM_ON_COPY
|
---|
632 | /* calculate the checksum of nocopy-data */
|
---|
633 | chksum = ~inet_chksum((const u8_t *)arg + pos, seglen);
|
---|
634 | if (seglen & 1) {
|
---|
635 | chksum_swapped = 1;
|
---|
636 | chksum = SWAP_BYTES_IN_WORD(chksum);
|
---|
637 | }
|
---|
638 | #endif /* TCP_CHECKSUM_ON_COPY */
|
---|
639 | /* reference the non-volatile payload data */
|
---|
640 | ((struct pbuf_rom *)p2)->payload = (const u8_t *)arg + pos;
|
---|
641 |
|
---|
642 | /* Second, allocate a pbuf for the headers. */
|
---|
643 | if ((p = pbuf_alloc(PBUF_TRANSPORT, optlen, PBUF_RAM)) == NULL) {
|
---|
644 | /* If allocation fails, we have to deallocate the data pbuf as
|
---|
645 | * well. */
|
---|
646 | pbuf_free(p2);
|
---|
647 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("tcp_write: could not allocate memory for header pbuf\n"));
|
---|
648 | goto memerr;
|
---|
649 | }
|
---|
650 | /* Concatenate the headers and data pbufs together. */
|
---|
651 | pbuf_cat(p/*header*/, p2/*data*/);
|
---|
652 | }
|
---|
653 |
|
---|
654 | queuelen += pbuf_clen(p);
|
---|
655 |
|
---|
656 | /* Now that there are more segments queued, we check again if the
|
---|
657 | * length of the queue exceeds the configured maximum or
|
---|
658 | * overflows. */
|
---|
659 | if (queuelen > LWIP_MIN(TCP_SND_QUEUELEN, TCP_SNDQUEUELEN_OVERFLOW)) {
|
---|
660 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("tcp_write: queue too long %"U16_F" (%d)\n",
|
---|
661 | queuelen, (int)TCP_SND_QUEUELEN));
|
---|
662 | pbuf_free(p);
|
---|
663 | goto memerr;
|
---|
664 | }
|
---|
665 |
|
---|
666 | if ((seg = tcp_create_segment(pcb, p, 0, pcb->snd_lbb + pos, optflags)) == NULL) {
|
---|
667 | goto memerr;
|
---|
668 | }
|
---|
669 | #if TCP_OVERSIZE_DBGCHECK
|
---|
670 | seg->oversize_left = oversize;
|
---|
671 | #endif /* TCP_OVERSIZE_DBGCHECK */
|
---|
672 | #if TCP_CHECKSUM_ON_COPY
|
---|
673 | seg->chksum = chksum;
|
---|
674 | seg->chksum_swapped = chksum_swapped;
|
---|
675 | seg->flags |= TF_SEG_DATA_CHECKSUMMED;
|
---|
676 | #endif /* TCP_CHECKSUM_ON_COPY */
|
---|
677 |
|
---|
678 | /* first segment of to-be-queued data? */
|
---|
679 | if (queue == NULL) {
|
---|
680 | queue = seg;
|
---|
681 | } else {
|
---|
682 | /* Attach the segment to the end of the queued segments */
|
---|
683 | LWIP_ASSERT("prev_seg != NULL", prev_seg != NULL);
|
---|
684 | prev_seg->next = seg;
|
---|
685 | }
|
---|
686 | /* remember last segment of to-be-queued data for next iteration */
|
---|
687 | prev_seg = seg;
|
---|
688 |
|
---|
689 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_TRACE, ("tcp_write: queueing %"U32_F":%"U32_F"\n",
|
---|
690 | lwip_ntohl(seg->tcphdr->seqno),
|
---|
691 | lwip_ntohl(seg->tcphdr->seqno) + TCP_TCPLEN(seg)));
|
---|
692 |
|
---|
693 | pos += seglen;
|
---|
694 | }
|
---|
695 |
|
---|
696 | /*
|
---|
697 | * All three segmentation phases were successful. We can commit the
|
---|
698 | * transaction.
|
---|
699 | */
|
---|
700 | #if TCP_OVERSIZE_DBGCHECK
|
---|
701 | if ((last_unsent != NULL) && (oversize_add != 0)) {
|
---|
702 | last_unsent->oversize_left += oversize_add;
|
---|
703 | }
|
---|
704 | #endif /* TCP_OVERSIZE_DBGCHECK */
|
---|
705 |
|
---|
706 | /*
|
---|
707 | * Phase 1: If data has been added to the preallocated tail of
|
---|
708 | * last_unsent, we update the length fields of the pbuf chain.
|
---|
709 | */
|
---|
710 | #if TCP_OVERSIZE
|
---|
711 | if (oversize_used > 0) {
|
---|
712 | struct pbuf *p;
|
---|
713 | /* Bump tot_len of whole chain, len of tail */
|
---|
714 | for (p = last_unsent->p; p; p = p->next) {
|
---|
715 | p->tot_len += oversize_used;
|
---|
716 | if (p->next == NULL) {
|
---|
717 | TCP_DATA_COPY((char *)p->payload + p->len, arg, oversize_used, last_unsent);
|
---|
718 | p->len += oversize_used;
|
---|
719 | }
|
---|
720 | }
|
---|
721 | last_unsent->len += oversize_used;
|
---|
722 | #if TCP_OVERSIZE_DBGCHECK
|
---|
723 | LWIP_ASSERT("last_unsent->oversize_left >= oversize_used",
|
---|
724 | last_unsent->oversize_left >= oversize_used);
|
---|
725 | last_unsent->oversize_left -= oversize_used;
|
---|
726 | #endif /* TCP_OVERSIZE_DBGCHECK */
|
---|
727 | }
|
---|
728 | pcb->unsent_oversize = oversize;
|
---|
729 | #endif /* TCP_OVERSIZE */
|
---|
730 |
|
---|
731 | /*
|
---|
732 | * Phase 2: concat_p can be concatenated onto last_unsent->p, unless we
|
---|
733 | * determined that the last ROM pbuf can be extended to include the new data.
|
---|
734 | */
|
---|
735 | if (concat_p != NULL) {
|
---|
736 | LWIP_ASSERT("tcp_write: cannot concatenate when pcb->unsent is empty",
|
---|
737 | (last_unsent != NULL));
|
---|
738 | pbuf_cat(last_unsent->p, concat_p);
|
---|
739 | last_unsent->len += concat_p->tot_len;
|
---|
740 | } else if (extendlen > 0) {
|
---|
741 | struct pbuf *p;
|
---|
742 | LWIP_ASSERT("tcp_write: extension of reference requires reference",
|
---|
743 | last_unsent != NULL && last_unsent->p != NULL);
|
---|
744 | for (p = last_unsent->p; p->next != NULL; p = p->next) {
|
---|
745 | p->tot_len += extendlen;
|
---|
746 | }
|
---|
747 | p->tot_len += extendlen;
|
---|
748 | p->len += extendlen;
|
---|
749 | last_unsent->len += extendlen;
|
---|
750 | }
|
---|
751 |
|
---|
752 | #if TCP_CHECKSUM_ON_COPY
|
---|
753 | if (concat_chksummed) {
|
---|
754 | LWIP_ASSERT("tcp_write: concat checksum needs concatenated data",
|
---|
755 | concat_p != NULL || extendlen > 0);
|
---|
756 | /*if concat checksumm swapped - swap it back */
|
---|
757 | if (concat_chksum_swapped) {
|
---|
758 | concat_chksum = SWAP_BYTES_IN_WORD(concat_chksum);
|
---|
759 | }
|
---|
760 | tcp_seg_add_chksum(concat_chksum, concat_chksummed, &last_unsent->chksum,
|
---|
761 | &last_unsent->chksum_swapped);
|
---|
762 | last_unsent->flags |= TF_SEG_DATA_CHECKSUMMED;
|
---|
763 | }
|
---|
764 | #endif /* TCP_CHECKSUM_ON_COPY */
|
---|
765 |
|
---|
766 | /*
|
---|
767 | * Phase 3: Append queue to pcb->unsent. Queue may be NULL, but that
|
---|
768 | * is harmless
|
---|
769 | */
|
---|
770 | if (last_unsent == NULL) {
|
---|
771 | pcb->unsent = queue;
|
---|
772 | } else {
|
---|
773 | last_unsent->next = queue;
|
---|
774 | }
|
---|
775 |
|
---|
776 | /*
|
---|
777 | * Finally update the pcb state.
|
---|
778 | */
|
---|
779 | pcb->snd_lbb += len;
|
---|
780 | pcb->snd_buf -= len;
|
---|
781 | pcb->snd_queuelen = queuelen;
|
---|
782 |
|
---|
783 | LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_write: %"S16_F" (after enqueued)\n",
|
---|
784 | pcb->snd_queuelen));
|
---|
785 | if (pcb->snd_queuelen != 0) {
|
---|
786 | LWIP_ASSERT("tcp_write: valid queue length",
|
---|
787 | pcb->unacked != NULL || pcb->unsent != NULL);
|
---|
788 | }
|
---|
789 |
|
---|
790 | /* Set the PSH flag in the last segment that we enqueued. */
|
---|
791 | if (seg != NULL && seg->tcphdr != NULL && ((apiflags & TCP_WRITE_FLAG_MORE) == 0)) {
|
---|
792 | TCPH_SET_FLAG(seg->tcphdr, TCP_PSH);
|
---|
793 | }
|
---|
794 |
|
---|
795 | return ERR_OK;
|
---|
796 | memerr:
|
---|
797 | tcp_set_flags(pcb, TF_NAGLEMEMERR);
|
---|
798 | TCP_STATS_INC(tcp.memerr);
|
---|
799 |
|
---|
800 | if (concat_p != NULL) {
|
---|
801 | pbuf_free(concat_p);
|
---|
802 | }
|
---|
803 | if (queue != NULL) {
|
---|
804 | tcp_segs_free(queue);
|
---|
805 | }
|
---|
806 | if (pcb->snd_queuelen != 0) {
|
---|
807 | LWIP_ASSERT("tcp_write: valid queue length", pcb->unacked != NULL ||
|
---|
808 | pcb->unsent != NULL);
|
---|
809 | }
|
---|
810 | LWIP_DEBUGF(TCP_QLEN_DEBUG | LWIP_DBG_STATE, ("tcp_write: %"S16_F" (with mem err)\n", pcb->snd_queuelen));
|
---|
811 | return ERR_MEM;
|
---|
812 | }
|
---|
813 |
|
---|
814 | /**
|
---|
815 | * Split segment on the head of the unsent queue. If return is not
|
---|
816 | * ERR_OK, existing head remains intact
|
---|
817 | *
|
---|
818 | * The split is accomplished by creating a new TCP segment and pbuf
|
---|
819 | * which holds the remainder payload after the split. The original
|
---|
820 | * pbuf is trimmed to new length. This allows splitting of read-only
|
---|
821 | * pbufs
|
---|
822 | *
|
---|
823 | * @param pcb the tcp_pcb for which to split the unsent head
|
---|
824 | * @param split the amount of payload to remain in the head
|
---|
825 | */
|
---|
826 | err_t
|
---|
827 | tcp_split_unsent_seg(struct tcp_pcb *pcb, u16_t split)
|
---|
828 | {
|
---|
829 | struct tcp_seg *seg = NULL, *useg = NULL;
|
---|
830 | struct pbuf *p = NULL;
|
---|
831 | u8_t optlen;
|
---|
832 | u8_t optflags;
|
---|
833 | u8_t split_flags;
|
---|
834 | u8_t remainder_flags;
|
---|
835 | u16_t remainder;
|
---|
836 | u16_t offset;
|
---|
837 | #if TCP_CHECKSUM_ON_COPY
|
---|
838 | u16_t chksum = 0;
|
---|
839 | u8_t chksum_swapped = 0;
|
---|
840 | struct pbuf *q;
|
---|
841 | #endif /* TCP_CHECKSUM_ON_COPY */
|
---|
842 |
|
---|
843 | LWIP_ASSERT("tcp_split_unsent_seg: invalid pcb", pcb != NULL);
|
---|
844 |
|
---|
845 | useg = pcb->unsent;
|
---|
846 | if (useg == NULL) {
|
---|
847 | return ERR_MEM;
|
---|
848 | }
|
---|
849 |
|
---|
850 | if (split == 0) {
|
---|
851 | LWIP_ASSERT("Can't split segment into length 0", 0);
|
---|
852 | return ERR_VAL;
|
---|
853 | }
|
---|
854 |
|
---|
855 | if (useg->len <= split) {
|
---|
856 | return ERR_OK;
|
---|
857 | }
|
---|
858 |
|
---|
859 | LWIP_ASSERT("split <= mss", split <= pcb->mss);
|
---|
860 | LWIP_ASSERT("useg->len > 0", useg->len > 0);
|
---|
861 |
|
---|
862 | /* We should check that we don't exceed TCP_SND_QUEUELEN but we need
|
---|
863 | * to split this packet so we may actually exceed the max value by
|
---|
864 | * one!
|
---|
865 | */
|
---|
866 | LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_enqueue: split_unsent_seg: %u\n", (unsigned int)pcb->snd_queuelen));
|
---|
867 |
|
---|
868 | optflags = useg->flags;
|
---|
869 | #if TCP_CHECKSUM_ON_COPY
|
---|
870 | /* Remove since checksum is not stored until after tcp_create_segment() */
|
---|
871 | optflags &= ~TF_SEG_DATA_CHECKSUMMED;
|
---|
872 | #endif /* TCP_CHECKSUM_ON_COPY */
|
---|
873 | optlen = LWIP_TCP_OPT_LENGTH(optflags);
|
---|
874 | remainder = useg->len - split;
|
---|
875 |
|
---|
876 | /* Create new pbuf for the remainder of the split */
|
---|
877 | p = pbuf_alloc(PBUF_TRANSPORT, remainder + optlen, PBUF_RAM);
|
---|
878 | if (p == NULL) {
|
---|
879 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_LEVEL_SERIOUS,
|
---|
880 | ("tcp_split_unsent_seg: could not allocate memory for pbuf remainder %u\n", remainder));
|
---|
881 | goto memerr;
|
---|
882 | }
|
---|
883 |
|
---|
884 | /* Offset into the original pbuf is past TCP/IP headers, options, and split amount */
|
---|
885 | offset = useg->p->tot_len - useg->len + split;
|
---|
886 | /* Copy remainder into new pbuf, headers and options will not be filled out */
|
---|
887 | if (pbuf_copy_partial(useg->p, (u8_t *)p->payload + optlen, remainder, offset ) != remainder) {
|
---|
888 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_LEVEL_SERIOUS,
|
---|
889 | ("tcp_split_unsent_seg: could not copy pbuf remainder %u\n", remainder));
|
---|
890 | goto memerr;
|
---|
891 | }
|
---|
892 | #if TCP_CHECKSUM_ON_COPY
|
---|
893 | /* calculate the checksum on remainder data */
|
---|
894 | tcp_seg_add_chksum(~inet_chksum((const u8_t *)p->payload + optlen, remainder), remainder,
|
---|
895 | &chksum, &chksum_swapped);
|
---|
896 | #endif /* TCP_CHECKSUM_ON_COPY */
|
---|
897 |
|
---|
898 | /* Options are created when calling tcp_output() */
|
---|
899 |
|
---|
900 | /* Migrate flags from original segment */
|
---|
901 | split_flags = TCPH_FLAGS(useg->tcphdr);
|
---|
902 | remainder_flags = 0; /* ACK added in tcp_output() */
|
---|
903 |
|
---|
904 | if (split_flags & TCP_PSH) {
|
---|
905 | split_flags &= ~TCP_PSH;
|
---|
906 | remainder_flags |= TCP_PSH;
|
---|
907 | }
|
---|
908 | if (split_flags & TCP_FIN) {
|
---|
909 | split_flags &= ~TCP_FIN;
|
---|
910 | remainder_flags |= TCP_FIN;
|
---|
911 | }
|
---|
912 | /* SYN should be left on split, RST should not be present with data */
|
---|
913 |
|
---|
914 | seg = tcp_create_segment(pcb, p, remainder_flags, lwip_ntohl(useg->tcphdr->seqno) + split, optflags);
|
---|
915 | if (seg == NULL) {
|
---|
916 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_LEVEL_SERIOUS,
|
---|
917 | ("tcp_split_unsent_seg: could not create new TCP segment\n"));
|
---|
918 | goto memerr;
|
---|
919 | }
|
---|
920 |
|
---|
921 | #if TCP_CHECKSUM_ON_COPY
|
---|
922 | seg->chksum = chksum;
|
---|
923 | seg->chksum_swapped = chksum_swapped;
|
---|
924 | seg->flags |= TF_SEG_DATA_CHECKSUMMED;
|
---|
925 | #endif /* TCP_CHECKSUM_ON_COPY */
|
---|
926 |
|
---|
927 | /* Remove this segment from the queue since trimming it may free pbufs */
|
---|
928 | pcb->snd_queuelen -= pbuf_clen(useg->p);
|
---|
929 |
|
---|
930 | /* Trim the original pbuf into our split size. At this point our remainder segment must be setup
|
---|
931 | successfully because we are modifying the original segment */
|
---|
932 | pbuf_realloc(useg->p, useg->p->tot_len - remainder);
|
---|
933 | useg->len -= remainder;
|
---|
934 | TCPH_SET_FLAG(useg->tcphdr, split_flags);
|
---|
935 | #if TCP_OVERSIZE_DBGCHECK
|
---|
936 | /* By trimming, realloc may have actually shrunk the pbuf, so clear oversize_left */
|
---|
937 | useg->oversize_left = 0;
|
---|
938 | #endif /* TCP_OVERSIZE_DBGCHECK */
|
---|
939 |
|
---|
940 | /* Add back to the queue with new trimmed pbuf */
|
---|
941 | pcb->snd_queuelen += pbuf_clen(useg->p);
|
---|
942 |
|
---|
943 | #if TCP_CHECKSUM_ON_COPY
|
---|
944 | /* The checksum on the split segment is now incorrect. We need to re-run it over the split */
|
---|
945 | useg->chksum = 0;
|
---|
946 | useg->chksum_swapped = 0;
|
---|
947 | q = useg->p;
|
---|
948 | offset = q->tot_len - useg->len; /* Offset due to exposed headers */
|
---|
949 |
|
---|
950 | /* Advance to the pbuf where the offset ends */
|
---|
951 | while (q != NULL && offset > q->len) {
|
---|
952 | offset -= q->len;
|
---|
953 | q = q->next;
|
---|
954 | }
|
---|
955 | LWIP_ASSERT("Found start of payload pbuf", q != NULL);
|
---|
956 | /* Checksum the first payload pbuf accounting for offset, then other pbufs are all payload */
|
---|
957 | for (; q != NULL; offset = 0, q = q->next) {
|
---|
958 | tcp_seg_add_chksum(~inet_chksum((const u8_t *)q->payload + offset, q->len - offset), q->len - offset,
|
---|
959 | &useg->chksum, &useg->chksum_swapped);
|
---|
960 | }
|
---|
961 | #endif /* TCP_CHECKSUM_ON_COPY */
|
---|
962 |
|
---|
963 | /* Update number of segments on the queues. Note that length now may
|
---|
964 | * exceed TCP_SND_QUEUELEN! We don't have to touch pcb->snd_buf
|
---|
965 | * because the total amount of data is constant when packet is split */
|
---|
966 | pcb->snd_queuelen += pbuf_clen(seg->p);
|
---|
967 |
|
---|
968 | /* Finally insert remainder into queue after split (which stays head) */
|
---|
969 | seg->next = useg->next;
|
---|
970 | useg->next = seg;
|
---|
971 |
|
---|
972 | #if TCP_OVERSIZE
|
---|
973 | /* If remainder is last segment on the unsent, ensure we clear the oversize amount
|
---|
974 | * because the remainder is always sized to the exact remaining amount */
|
---|
975 | if (seg->next == NULL) {
|
---|
976 | pcb->unsent_oversize = 0;
|
---|
977 | }
|
---|
978 | #endif /* TCP_OVERSIZE */
|
---|
979 |
|
---|
980 | return ERR_OK;
|
---|
981 | memerr:
|
---|
982 | TCP_STATS_INC(tcp.memerr);
|
---|
983 |
|
---|
984 | LWIP_ASSERT("seg == NULL", seg == NULL);
|
---|
985 | if (p != NULL) {
|
---|
986 | pbuf_free(p);
|
---|
987 | }
|
---|
988 |
|
---|
989 | return ERR_MEM;
|
---|
990 | }
|
---|
991 |
|
---|
992 | /**
|
---|
993 | * Called by tcp_close() to send a segment including FIN flag but not data.
|
---|
994 | * This FIN may be added to an existing segment or a new, otherwise empty
|
---|
995 | * segment is enqueued.
|
---|
996 | *
|
---|
997 | * @param pcb the tcp_pcb over which to send a segment
|
---|
998 | * @return ERR_OK if sent, another err_t otherwise
|
---|
999 | */
|
---|
1000 | err_t
|
---|
1001 | tcp_send_fin(struct tcp_pcb *pcb)
|
---|
1002 | {
|
---|
1003 | LWIP_ASSERT("tcp_send_fin: invalid pcb", pcb != NULL);
|
---|
1004 |
|
---|
1005 | /* first, try to add the fin to the last unsent segment */
|
---|
1006 | if (pcb->unsent != NULL) {
|
---|
1007 | struct tcp_seg *last_unsent;
|
---|
1008 | for (last_unsent = pcb->unsent; last_unsent->next != NULL;
|
---|
1009 | last_unsent = last_unsent->next);
|
---|
1010 |
|
---|
1011 | if ((TCPH_FLAGS(last_unsent->tcphdr) & (TCP_SYN | TCP_FIN | TCP_RST)) == 0) {
|
---|
1012 | /* no SYN/FIN/RST flag in the header, we can add the FIN flag */
|
---|
1013 | TCPH_SET_FLAG(last_unsent->tcphdr, TCP_FIN);
|
---|
1014 | tcp_set_flags(pcb, TF_FIN);
|
---|
1015 | return ERR_OK;
|
---|
1016 | }
|
---|
1017 | }
|
---|
1018 | /* no data, no length, flags, copy=1, no optdata */
|
---|
1019 | return tcp_enqueue_flags(pcb, TCP_FIN);
|
---|
1020 | }
|
---|
1021 |
|
---|
1022 | /**
|
---|
1023 | * Enqueue SYN or FIN for transmission.
|
---|
1024 | *
|
---|
1025 | * Called by @ref tcp_connect, tcp_listen_input, and @ref tcp_close
|
---|
1026 | * (via @ref tcp_send_fin)
|
---|
1027 | *
|
---|
1028 | * @param pcb Protocol control block for the TCP connection.
|
---|
1029 | * @param flags TCP header flags to set in the outgoing segment.
|
---|
1030 | */
|
---|
1031 | err_t
|
---|
1032 | tcp_enqueue_flags(struct tcp_pcb *pcb, u8_t flags)
|
---|
1033 | {
|
---|
1034 | struct pbuf *p;
|
---|
1035 | struct tcp_seg *seg;
|
---|
1036 | u8_t optflags = 0;
|
---|
1037 | u8_t optlen = 0;
|
---|
1038 |
|
---|
1039 | LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_enqueue_flags: queuelen: %"U16_F"\n", (u16_t)pcb->snd_queuelen));
|
---|
1040 |
|
---|
1041 | LWIP_ASSERT("tcp_enqueue_flags: need either TCP_SYN or TCP_FIN in flags (programmer violates API)",
|
---|
1042 | (flags & (TCP_SYN | TCP_FIN)) != 0);
|
---|
1043 | LWIP_ASSERT("tcp_enqueue_flags: invalid pcb", pcb != NULL);
|
---|
1044 |
|
---|
1045 | /* No need to check pcb->snd_queuelen if only SYN or FIN are allowed! */
|
---|
1046 |
|
---|
1047 | /* Get options for this segment. This is a special case since this is the
|
---|
1048 | only place where a SYN can be sent. */
|
---|
1049 | if (flags & TCP_SYN) {
|
---|
1050 | optflags = TF_SEG_OPTS_MSS;
|
---|
1051 | #if LWIP_WND_SCALE
|
---|
1052 | if ((pcb->state != SYN_RCVD) || (pcb->flags & TF_WND_SCALE)) {
|
---|
1053 | /* In a <SYN,ACK> (sent in state SYN_RCVD), the window scale option may only
|
---|
1054 | be sent if we received a window scale option from the remote host. */
|
---|
1055 | optflags |= TF_SEG_OPTS_WND_SCALE;
|
---|
1056 | }
|
---|
1057 | #endif /* LWIP_WND_SCALE */
|
---|
1058 | #if LWIP_TCP_SACK_OUT
|
---|
1059 | if ((pcb->state != SYN_RCVD) || (pcb->flags & TF_SACK)) {
|
---|
1060 | /* In a <SYN,ACK> (sent in state SYN_RCVD), the SACK_PERM option may only
|
---|
1061 | be sent if we received a SACK_PERM option from the remote host. */
|
---|
1062 | optflags |= TF_SEG_OPTS_SACK_PERM;
|
---|
1063 | }
|
---|
1064 | #endif /* LWIP_TCP_SACK_OUT */
|
---|
1065 | }
|
---|
1066 | #if LWIP_TCP_TIMESTAMPS
|
---|
1067 | if ((pcb->flags & TF_TIMESTAMP) || ((flags & TCP_SYN) && (pcb->state != SYN_RCVD))) {
|
---|
1068 | /* Make sure the timestamp option is only included in data segments if we
|
---|
1069 | agreed about it with the remote host (and in active open SYN segments). */
|
---|
1070 | optflags |= TF_SEG_OPTS_TS;
|
---|
1071 | }
|
---|
1072 | #endif /* LWIP_TCP_TIMESTAMPS */
|
---|
1073 | optlen = LWIP_TCP_OPT_LENGTH_SEGMENT(optflags, pcb);
|
---|
1074 |
|
---|
1075 | /* Allocate pbuf with room for TCP header + options */
|
---|
1076 | if ((p = pbuf_alloc(PBUF_TRANSPORT, optlen, PBUF_RAM)) == NULL) {
|
---|
1077 | tcp_set_flags(pcb, TF_NAGLEMEMERR);
|
---|
1078 | TCP_STATS_INC(tcp.memerr);
|
---|
1079 | return ERR_MEM;
|
---|
1080 | }
|
---|
1081 | LWIP_ASSERT("tcp_enqueue_flags: check that first pbuf can hold optlen",
|
---|
1082 | (p->len >= optlen));
|
---|
1083 |
|
---|
1084 | /* Allocate memory for tcp_seg, and fill in fields. */
|
---|
1085 | if ((seg = tcp_create_segment(pcb, p, flags, pcb->snd_lbb, optflags)) == NULL) {
|
---|
1086 | tcp_set_flags(pcb, TF_NAGLEMEMERR);
|
---|
1087 | TCP_STATS_INC(tcp.memerr);
|
---|
1088 | return ERR_MEM;
|
---|
1089 | }
|
---|
1090 | LWIP_ASSERT("seg->tcphdr not aligned", ((mem_ptr_t)seg->tcphdr % LWIP_MIN(MEM_ALIGNMENT, 4)) == 0);
|
---|
1091 | LWIP_ASSERT("tcp_enqueue_flags: invalid segment length", seg->len == 0);
|
---|
1092 |
|
---|
1093 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_TRACE,
|
---|
1094 | ("tcp_enqueue_flags: queueing %"U32_F":%"U32_F" (0x%"X16_F")\n",
|
---|
1095 | lwip_ntohl(seg->tcphdr->seqno),
|
---|
1096 | lwip_ntohl(seg->tcphdr->seqno) + TCP_TCPLEN(seg),
|
---|
1097 | (u16_t)flags));
|
---|
1098 |
|
---|
1099 | /* Now append seg to pcb->unsent queue */
|
---|
1100 | if (pcb->unsent == NULL) {
|
---|
1101 | pcb->unsent = seg;
|
---|
1102 | } else {
|
---|
1103 | struct tcp_seg *useg;
|
---|
1104 | for (useg = pcb->unsent; useg->next != NULL; useg = useg->next);
|
---|
1105 | useg->next = seg;
|
---|
1106 | }
|
---|
1107 | #if TCP_OVERSIZE
|
---|
1108 | /* The new unsent tail has no space */
|
---|
1109 | pcb->unsent_oversize = 0;
|
---|
1110 | #endif /* TCP_OVERSIZE */
|
---|
1111 |
|
---|
1112 | /* SYN and FIN bump the sequence number */
|
---|
1113 | if ((flags & TCP_SYN) || (flags & TCP_FIN)) {
|
---|
1114 | pcb->snd_lbb++;
|
---|
1115 | /* optlen does not influence snd_buf */
|
---|
1116 | }
|
---|
1117 | if (flags & TCP_FIN) {
|
---|
1118 | tcp_set_flags(pcb, TF_FIN);
|
---|
1119 | }
|
---|
1120 |
|
---|
1121 | /* update number of segments on the queues */
|
---|
1122 | pcb->snd_queuelen += pbuf_clen(seg->p);
|
---|
1123 | LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_enqueue_flags: %"S16_F" (after enqueued)\n", pcb->snd_queuelen));
|
---|
1124 | if (pcb->snd_queuelen != 0) {
|
---|
1125 | LWIP_ASSERT("tcp_enqueue_flags: invalid queue length",
|
---|
1126 | pcb->unacked != NULL || pcb->unsent != NULL);
|
---|
1127 | }
|
---|
1128 |
|
---|
1129 | return ERR_OK;
|
---|
1130 | }
|
---|
1131 |
|
---|
1132 | #if LWIP_TCP_TIMESTAMPS
|
---|
1133 | /* Build a timestamp option (12 bytes long) at the specified options pointer)
|
---|
1134 | *
|
---|
1135 | * @param pcb tcp_pcb
|
---|
1136 | * @param opts option pointer where to store the timestamp option
|
---|
1137 | */
|
---|
1138 | static void
|
---|
1139 | tcp_build_timestamp_option(const struct tcp_pcb *pcb, u32_t *opts)
|
---|
1140 | {
|
---|
1141 | LWIP_ASSERT("tcp_build_timestamp_option: invalid pcb", pcb != NULL);
|
---|
1142 |
|
---|
1143 | /* Pad with two NOP options to make everything nicely aligned */
|
---|
1144 | opts[0] = PP_HTONL(0x0101080A);
|
---|
1145 | opts[1] = lwip_htonl(sys_now());
|
---|
1146 | opts[2] = lwip_htonl(pcb->ts_recent);
|
---|
1147 | }
|
---|
1148 | #endif
|
---|
1149 |
|
---|
1150 | #if LWIP_TCP_SACK_OUT
|
---|
1151 | /**
|
---|
1152 | * Calculates the number of SACK entries that should be generated.
|
---|
1153 | * It takes into account whether TF_SACK flag is set,
|
---|
1154 | * the number of SACK entries in tcp_pcb that are valid,
|
---|
1155 | * as well as the available options size.
|
---|
1156 | *
|
---|
1157 | * @param pcb tcp_pcb
|
---|
1158 | * @param optlen the length of other TCP options (in bytes)
|
---|
1159 | * @return the number of SACK ranges that can be used
|
---|
1160 | */
|
---|
1161 | static u8_t
|
---|
1162 | tcp_get_num_sacks(const struct tcp_pcb *pcb, u8_t optlen)
|
---|
1163 | {
|
---|
1164 | u8_t num_sacks = 0;
|
---|
1165 |
|
---|
1166 | LWIP_ASSERT("tcp_get_num_sacks: invalid pcb", pcb != NULL);
|
---|
1167 |
|
---|
1168 | if (pcb->flags & TF_SACK) {
|
---|
1169 | u8_t i;
|
---|
1170 |
|
---|
1171 | /* The first SACK takes up 12 bytes (it includes SACK header and two NOP options),
|
---|
1172 | each additional one - 8 bytes. */
|
---|
1173 | optlen += 12;
|
---|
1174 |
|
---|
1175 | /* Max options size = 40, number of SACK array entries = LWIP_TCP_MAX_SACK_NUM */
|
---|
1176 | for (i = 0; (i < LWIP_TCP_MAX_SACK_NUM) && (optlen <= TCP_MAX_OPTION_BYTES) &&
|
---|
1177 | LWIP_TCP_SACK_VALID(pcb, i); ++i) {
|
---|
1178 | ++num_sacks;
|
---|
1179 | optlen += 8;
|
---|
1180 | }
|
---|
1181 | }
|
---|
1182 |
|
---|
1183 | return num_sacks;
|
---|
1184 | }
|
---|
1185 |
|
---|
1186 | /** Build a SACK option (12 or more bytes long) at the specified options pointer)
|
---|
1187 | *
|
---|
1188 | * @param pcb tcp_pcb
|
---|
1189 | * @param opts option pointer where to store the SACK option
|
---|
1190 | * @param num_sacks the number of SACKs to store
|
---|
1191 | */
|
---|
1192 | static void
|
---|
1193 | tcp_build_sack_option(const struct tcp_pcb *pcb, u32_t *opts, u8_t num_sacks)
|
---|
1194 | {
|
---|
1195 | u8_t i;
|
---|
1196 |
|
---|
1197 | LWIP_ASSERT("tcp_build_sack_option: invalid pcb", pcb != NULL);
|
---|
1198 | LWIP_ASSERT("tcp_build_sack_option: invalid opts", opts != NULL);
|
---|
1199 |
|
---|
1200 | /* Pad with two NOP options to make everything nicely aligned.
|
---|
1201 | We add the length (of just the SACK option, not the NOPs in front of it),
|
---|
1202 | which is 2B of header, plus 8B for each SACK. */
|
---|
1203 | *(opts++) = PP_HTONL(0x01010500 + 2 + num_sacks * 8);
|
---|
1204 |
|
---|
1205 | for (i = 0; i < num_sacks; ++i) {
|
---|
1206 | *(opts++) = lwip_htonl(pcb->rcv_sacks[i].left);
|
---|
1207 | *(opts++) = lwip_htonl(pcb->rcv_sacks[i].right);
|
---|
1208 | }
|
---|
1209 | }
|
---|
1210 |
|
---|
1211 | #endif
|
---|
1212 |
|
---|
1213 | #if LWIP_WND_SCALE
|
---|
1214 | /** Build a window scale option (3 bytes long) at the specified options pointer)
|
---|
1215 | *
|
---|
1216 | * @param opts option pointer where to store the window scale option
|
---|
1217 | */
|
---|
1218 | static void
|
---|
1219 | tcp_build_wnd_scale_option(u32_t *opts)
|
---|
1220 | {
|
---|
1221 | LWIP_ASSERT("tcp_build_wnd_scale_option: invalid opts", opts != NULL);
|
---|
1222 |
|
---|
1223 | /* Pad with one NOP option to make everything nicely aligned */
|
---|
1224 | opts[0] = PP_HTONL(0x01030300 | TCP_RCV_SCALE);
|
---|
1225 | }
|
---|
1226 | #endif
|
---|
1227 |
|
---|
1228 | /**
|
---|
1229 | * @ingroup tcp_raw
|
---|
1230 | * Find out what we can send and send it
|
---|
1231 | *
|
---|
1232 | * @param pcb Protocol control block for the TCP connection to send data
|
---|
1233 | * @return ERR_OK if data has been sent or nothing to send
|
---|
1234 | * another err_t on error
|
---|
1235 | */
|
---|
1236 | err_t
|
---|
1237 | tcp_output(struct tcp_pcb *pcb)
|
---|
1238 | {
|
---|
1239 | struct tcp_seg *seg, *useg;
|
---|
1240 | u32_t wnd, snd_nxt;
|
---|
1241 | err_t err;
|
---|
1242 | struct netif *netif;
|
---|
1243 | #if TCP_CWND_DEBUG
|
---|
1244 | s16_t i = 0;
|
---|
1245 | #endif /* TCP_CWND_DEBUG */
|
---|
1246 |
|
---|
1247 | LWIP_ASSERT_CORE_LOCKED();
|
---|
1248 |
|
---|
1249 | LWIP_ASSERT("tcp_output: invalid pcb", pcb != NULL);
|
---|
1250 | /* pcb->state LISTEN not allowed here */
|
---|
1251 | LWIP_ASSERT("don't call tcp_output for listen-pcbs",
|
---|
1252 | pcb->state != LISTEN);
|
---|
1253 |
|
---|
1254 | /* First, check if we are invoked by the TCP input processing
|
---|
1255 | code. If so, we do not output anything. Instead, we rely on the
|
---|
1256 | input processing code to call us when input processing is done
|
---|
1257 | with. */
|
---|
1258 | if (tcp_input_pcb == pcb) {
|
---|
1259 | return ERR_OK;
|
---|
1260 | }
|
---|
1261 |
|
---|
1262 | wnd = LWIP_MIN(pcb->snd_wnd, pcb->cwnd);
|
---|
1263 |
|
---|
1264 | seg = pcb->unsent;
|
---|
1265 |
|
---|
1266 | if (seg == NULL) {
|
---|
1267 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output: nothing to send (%p)\n",
|
---|
1268 | (void *)pcb->unsent));
|
---|
1269 | LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_output: snd_wnd %"TCPWNDSIZE_F
|
---|
1270 | ", cwnd %"TCPWNDSIZE_F", wnd %"U32_F
|
---|
1271 | ", seg == NULL, ack %"U32_F"\n",
|
---|
1272 | pcb->snd_wnd, pcb->cwnd, wnd, pcb->lastack));
|
---|
1273 |
|
---|
1274 | /* If the TF_ACK_NOW flag is set and the ->unsent queue is empty, construct
|
---|
1275 | * an empty ACK segment and send it. */
|
---|
1276 | if (pcb->flags & TF_ACK_NOW) {
|
---|
1277 | return tcp_send_empty_ack(pcb);
|
---|
1278 | }
|
---|
1279 | /* nothing to send: shortcut out of here */
|
---|
1280 | goto output_done;
|
---|
1281 | } else {
|
---|
1282 | LWIP_DEBUGF(TCP_CWND_DEBUG,
|
---|
1283 | ("tcp_output: snd_wnd %"TCPWNDSIZE_F", cwnd %"TCPWNDSIZE_F", wnd %"U32_F
|
---|
1284 | ", effwnd %"U32_F", seq %"U32_F", ack %"U32_F"\n",
|
---|
1285 | pcb->snd_wnd, pcb->cwnd, wnd,
|
---|
1286 | lwip_ntohl(seg->tcphdr->seqno) - pcb->lastack + seg->len,
|
---|
1287 | lwip_ntohl(seg->tcphdr->seqno), pcb->lastack));
|
---|
1288 | }
|
---|
1289 |
|
---|
1290 | netif = tcp_route(pcb, &pcb->local_ip, &pcb->remote_ip);
|
---|
1291 | if (netif == NULL) {
|
---|
1292 | return ERR_RTE;
|
---|
1293 | }
|
---|
1294 |
|
---|
1295 | /* If we don't have a local IP address, we get one from netif */
|
---|
1296 | if (ip_addr_isany(&pcb->local_ip)) {
|
---|
1297 | const ip_addr_t *local_ip = ip_netif_get_local_ip(netif, &pcb->remote_ip);
|
---|
1298 | if (local_ip == NULL) {
|
---|
1299 | return ERR_RTE;
|
---|
1300 | }
|
---|
1301 | ip_addr_copy(pcb->local_ip, *local_ip);
|
---|
1302 | }
|
---|
1303 |
|
---|
1304 | /* Handle the current segment not fitting within the window */
|
---|
1305 | if (lwip_ntohl(seg->tcphdr->seqno) - pcb->lastack + seg->len > wnd) {
|
---|
1306 | /* We need to start the persistent timer when the next unsent segment does not fit
|
---|
1307 | * within the remaining (could be 0) send window and RTO timer is not running (we
|
---|
1308 | * have no in-flight data). If window is still too small after persist timer fires,
|
---|
1309 | * then we split the segment. We don't consider the congestion window since a cwnd
|
---|
1310 | * smaller than 1 SMSS implies in-flight data
|
---|
1311 | */
|
---|
1312 | if (wnd == pcb->snd_wnd && pcb->unacked == NULL && pcb->persist_backoff == 0) {
|
---|
1313 | pcb->persist_cnt = 0;
|
---|
1314 | pcb->persist_backoff = 1;
|
---|
1315 | pcb->persist_probe = 0;
|
---|
1316 | }
|
---|
1317 | /* We need an ACK, but can't send data now, so send an empty ACK */
|
---|
1318 | if (pcb->flags & TF_ACK_NOW) {
|
---|
1319 | return tcp_send_empty_ack(pcb);
|
---|
1320 | }
|
---|
1321 | goto output_done;
|
---|
1322 | }
|
---|
1323 | /* Stop persist timer, above conditions are not active */
|
---|
1324 | pcb->persist_backoff = 0;
|
---|
1325 |
|
---|
1326 | /* useg should point to last segment on unacked queue */
|
---|
1327 | useg = pcb->unacked;
|
---|
1328 | if (useg != NULL) {
|
---|
1329 | for (; useg->next != NULL; useg = useg->next);
|
---|
1330 | }
|
---|
1331 | /* data available and window allows it to be sent? */
|
---|
1332 | while (seg != NULL &&
|
---|
1333 | lwip_ntohl(seg->tcphdr->seqno) - pcb->lastack + seg->len <= wnd) {
|
---|
1334 | LWIP_ASSERT("RST not expected here!",
|
---|
1335 | (TCPH_FLAGS(seg->tcphdr) & TCP_RST) == 0);
|
---|
1336 | /* Stop sending if the nagle algorithm would prevent it
|
---|
1337 | * Don't stop:
|
---|
1338 | * - if tcp_write had a memory error before (prevent delayed ACK timeout) or
|
---|
1339 | * - if FIN was already enqueued for this PCB (SYN is always alone in a segment -
|
---|
1340 | * either seg->next != NULL or pcb->unacked == NULL;
|
---|
1341 | * RST is no sent using tcp_write/tcp_output.
|
---|
1342 | */
|
---|
1343 | if ((tcp_do_output_nagle(pcb) == 0) &&
|
---|
1344 | ((pcb->flags & (TF_NAGLEMEMERR | TF_FIN)) == 0)) {
|
---|
1345 | break;
|
---|
1346 | }
|
---|
1347 | #if TCP_CWND_DEBUG
|
---|
1348 | LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_output: snd_wnd %"TCPWNDSIZE_F", cwnd %"TCPWNDSIZE_F", wnd %"U32_F", effwnd %"U32_F", seq %"U32_F", ack %"U32_F", i %"S16_F"\n",
|
---|
1349 | pcb->snd_wnd, pcb->cwnd, wnd,
|
---|
1350 | lwip_ntohl(seg->tcphdr->seqno) + seg->len -
|
---|
1351 | pcb->lastack,
|
---|
1352 | lwip_ntohl(seg->tcphdr->seqno), pcb->lastack, i));
|
---|
1353 | ++i;
|
---|
1354 | #endif /* TCP_CWND_DEBUG */
|
---|
1355 |
|
---|
1356 | if (pcb->state != SYN_SENT) {
|
---|
1357 | TCPH_SET_FLAG(seg->tcphdr, TCP_ACK);
|
---|
1358 | }
|
---|
1359 |
|
---|
1360 | err = tcp_output_segment(seg, pcb, netif);
|
---|
1361 | if (err != ERR_OK) {
|
---|
1362 | /* segment could not be sent, for whatever reason */
|
---|
1363 | tcp_set_flags(pcb, TF_NAGLEMEMERR);
|
---|
1364 | return err;
|
---|
1365 | }
|
---|
1366 | #if TCP_OVERSIZE_DBGCHECK
|
---|
1367 | seg->oversize_left = 0;
|
---|
1368 | #endif /* TCP_OVERSIZE_DBGCHECK */
|
---|
1369 | pcb->unsent = seg->next;
|
---|
1370 | if (pcb->state != SYN_SENT) {
|
---|
1371 | tcp_clear_flags(pcb, TF_ACK_DELAY | TF_ACK_NOW);
|
---|
1372 | }
|
---|
1373 | snd_nxt = lwip_ntohl(seg->tcphdr->seqno) + TCP_TCPLEN(seg);
|
---|
1374 | if (TCP_SEQ_LT(pcb->snd_nxt, snd_nxt)) {
|
---|
1375 | pcb->snd_nxt = snd_nxt;
|
---|
1376 | }
|
---|
1377 | /* put segment on unacknowledged list if length > 0 */
|
---|
1378 | if (TCP_TCPLEN(seg) > 0) {
|
---|
1379 | seg->next = NULL;
|
---|
1380 | /* unacked list is empty? */
|
---|
1381 | if (pcb->unacked == NULL) {
|
---|
1382 | pcb->unacked = seg;
|
---|
1383 | useg = seg;
|
---|
1384 | /* unacked list is not empty? */
|
---|
1385 | } else {
|
---|
1386 | /* In the case of fast retransmit, the packet should not go to the tail
|
---|
1387 | * of the unacked queue, but rather somewhere before it. We need to check for
|
---|
1388 | * this case. -STJ Jul 27, 2004 */
|
---|
1389 | if (TCP_SEQ_LT(lwip_ntohl(seg->tcphdr->seqno), lwip_ntohl(useg->tcphdr->seqno))) {
|
---|
1390 | /* add segment to before tail of unacked list, keeping the list sorted */
|
---|
1391 | struct tcp_seg **cur_seg = &(pcb->unacked);
|
---|
1392 | while (*cur_seg &&
|
---|
1393 | TCP_SEQ_LT(lwip_ntohl((*cur_seg)->tcphdr->seqno), lwip_ntohl(seg->tcphdr->seqno))) {
|
---|
1394 | cur_seg = &((*cur_seg)->next );
|
---|
1395 | }
|
---|
1396 | seg->next = (*cur_seg);
|
---|
1397 | (*cur_seg) = seg;
|
---|
1398 | } else {
|
---|
1399 | /* add segment to tail of unacked list */
|
---|
1400 | useg->next = seg;
|
---|
1401 | useg = useg->next;
|
---|
1402 | }
|
---|
1403 | }
|
---|
1404 | /* do not queue empty segments on the unacked list */
|
---|
1405 | } else {
|
---|
1406 | tcp_seg_free(seg);
|
---|
1407 | }
|
---|
1408 | seg = pcb->unsent;
|
---|
1409 | }
|
---|
1410 | #if TCP_OVERSIZE
|
---|
1411 | if (pcb->unsent == NULL) {
|
---|
1412 | /* last unsent has been removed, reset unsent_oversize */
|
---|
1413 | pcb->unsent_oversize = 0;
|
---|
1414 | }
|
---|
1415 | #endif /* TCP_OVERSIZE */
|
---|
1416 |
|
---|
1417 | output_done:
|
---|
1418 | tcp_clear_flags(pcb, TF_NAGLEMEMERR);
|
---|
1419 | return ERR_OK;
|
---|
1420 | }
|
---|
1421 |
|
---|
1422 | /** Check if a segment's pbufs are used by someone else than TCP.
|
---|
1423 | * This can happen on retransmission if the pbuf of this segment is still
|
---|
1424 | * referenced by the netif driver due to deferred transmission.
|
---|
1425 | * This is the case (only!) if someone down the TX call path called
|
---|
1426 | * pbuf_ref() on one of the pbufs!
|
---|
1427 | *
|
---|
1428 | * @arg seg the tcp segment to check
|
---|
1429 | * @return 1 if ref != 1, 0 if ref == 1
|
---|
1430 | */
|
---|
1431 | static int
|
---|
1432 | tcp_output_segment_busy(const struct tcp_seg *seg)
|
---|
1433 | {
|
---|
1434 | LWIP_ASSERT("tcp_output_segment_busy: invalid seg", seg != NULL);
|
---|
1435 |
|
---|
1436 | /* We only need to check the first pbuf here:
|
---|
1437 | If a pbuf is queued for transmission, a driver calls pbuf_ref(),
|
---|
1438 | which only changes the ref count of the first pbuf */
|
---|
1439 | if (seg->p->ref != 1) {
|
---|
1440 | /* other reference found */
|
---|
1441 | return 1;
|
---|
1442 | }
|
---|
1443 | /* no other references found */
|
---|
1444 | return 0;
|
---|
1445 | }
|
---|
1446 |
|
---|
1447 | /**
|
---|
1448 | * Called by tcp_output() to actually send a TCP segment over IP.
|
---|
1449 | *
|
---|
1450 | * @param seg the tcp_seg to send
|
---|
1451 | * @param pcb the tcp_pcb for the TCP connection used to send the segment
|
---|
1452 | * @param netif the netif used to send the segment
|
---|
1453 | */
|
---|
1454 | static err_t
|
---|
1455 | tcp_output_segment(struct tcp_seg *seg, struct tcp_pcb *pcb, struct netif *netif)
|
---|
1456 | {
|
---|
1457 | err_t err;
|
---|
1458 | u16_t len;
|
---|
1459 | u32_t *opts;
|
---|
1460 | #if TCP_CHECKSUM_ON_COPY
|
---|
1461 | int seg_chksum_was_swapped = 0;
|
---|
1462 | #endif
|
---|
1463 |
|
---|
1464 | LWIP_ASSERT("tcp_output_segment: invalid seg", seg != NULL);
|
---|
1465 | LWIP_ASSERT("tcp_output_segment: invalid pcb", pcb != NULL);
|
---|
1466 | LWIP_ASSERT("tcp_output_segment: invalid netif", netif != NULL);
|
---|
1467 |
|
---|
1468 | if (tcp_output_segment_busy(seg)) {
|
---|
1469 | /* This should not happen: rexmit functions should have checked this.
|
---|
1470 | However, since this function modifies p->len, we must not continue in this case. */
|
---|
1471 | LWIP_DEBUGF(TCP_RTO_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("tcp_output_segment: segment busy\n"));
|
---|
1472 | return ERR_OK;
|
---|
1473 | }
|
---|
1474 |
|
---|
1475 | /* The TCP header has already been constructed, but the ackno and
|
---|
1476 | wnd fields remain. */
|
---|
1477 | seg->tcphdr->ackno = lwip_htonl(pcb->rcv_nxt);
|
---|
1478 |
|
---|
1479 | /* advertise our receive window size in this TCP segment */
|
---|
1480 | #if LWIP_WND_SCALE
|
---|
1481 | if (seg->flags & TF_SEG_OPTS_WND_SCALE) {
|
---|
1482 | /* The Window field in a SYN segment itself (the only type where we send
|
---|
1483 | the window scale option) is never scaled. */
|
---|
1484 | seg->tcphdr->wnd = lwip_htons(TCPWND_MIN16(pcb->rcv_ann_wnd));
|
---|
1485 | } else
|
---|
1486 | #endif /* LWIP_WND_SCALE */
|
---|
1487 | {
|
---|
1488 | seg->tcphdr->wnd = lwip_htons(TCPWND_MIN16(RCV_WND_SCALE(pcb, pcb->rcv_ann_wnd)));
|
---|
1489 | }
|
---|
1490 |
|
---|
1491 | pcb->rcv_ann_right_edge = pcb->rcv_nxt + pcb->rcv_ann_wnd;
|
---|
1492 |
|
---|
1493 | /* Add any requested options. NB MSS option is only set on SYN
|
---|
1494 | packets, so ignore it here */
|
---|
1495 | /* cast through void* to get rid of alignment warnings */
|
---|
1496 | opts = (u32_t *)(void *)(seg->tcphdr + 1);
|
---|
1497 | if (seg->flags & TF_SEG_OPTS_MSS) {
|
---|
1498 | u16_t mss;
|
---|
1499 | #if TCP_CALCULATE_EFF_SEND_MSS
|
---|
1500 | mss = tcp_eff_send_mss_netif(TCP_MSS, netif, &pcb->remote_ip);
|
---|
1501 | #else /* TCP_CALCULATE_EFF_SEND_MSS */
|
---|
1502 | mss = TCP_MSS;
|
---|
1503 | #endif /* TCP_CALCULATE_EFF_SEND_MSS */
|
---|
1504 | *opts = TCP_BUILD_MSS_OPTION(mss);
|
---|
1505 | opts += 1;
|
---|
1506 | }
|
---|
1507 | #if LWIP_TCP_TIMESTAMPS
|
---|
1508 | pcb->ts_lastacksent = pcb->rcv_nxt;
|
---|
1509 |
|
---|
1510 | if (seg->flags & TF_SEG_OPTS_TS) {
|
---|
1511 | tcp_build_timestamp_option(pcb, opts);
|
---|
1512 | opts += 3;
|
---|
1513 | }
|
---|
1514 | #endif
|
---|
1515 | #if LWIP_WND_SCALE
|
---|
1516 | if (seg->flags & TF_SEG_OPTS_WND_SCALE) {
|
---|
1517 | tcp_build_wnd_scale_option(opts);
|
---|
1518 | opts += 1;
|
---|
1519 | }
|
---|
1520 | #endif
|
---|
1521 | #if LWIP_TCP_SACK_OUT
|
---|
1522 | if (seg->flags & TF_SEG_OPTS_SACK_PERM) {
|
---|
1523 | /* Pad with two NOP options to make everything nicely aligned
|
---|
1524 | * NOTE: When we send both timestamp and SACK_PERM options,
|
---|
1525 | * we could use the first two NOPs before the timestamp to store SACK_PERM option,
|
---|
1526 | * but that would complicate the code.
|
---|
1527 | */
|
---|
1528 | *(opts++) = PP_HTONL(0x01010402);
|
---|
1529 | }
|
---|
1530 | #endif
|
---|
1531 |
|
---|
1532 | /* Set retransmission timer running if it is not currently enabled
|
---|
1533 | This must be set before checking the route. */
|
---|
1534 | if (pcb->rtime < 0) {
|
---|
1535 | pcb->rtime = 0;
|
---|
1536 | }
|
---|
1537 |
|
---|
1538 | if (pcb->rttest == 0) {
|
---|
1539 | pcb->rttest = tcp_ticks;
|
---|
1540 | pcb->rtseq = lwip_ntohl(seg->tcphdr->seqno);
|
---|
1541 |
|
---|
1542 | LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_output_segment: rtseq %"U32_F"\n", pcb->rtseq));
|
---|
1543 | }
|
---|
1544 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output_segment: %"U32_F":%"U32_F"\n",
|
---|
1545 | lwip_htonl(seg->tcphdr->seqno), lwip_htonl(seg->tcphdr->seqno) +
|
---|
1546 | seg->len));
|
---|
1547 |
|
---|
1548 | len = (u16_t)((u8_t *)seg->tcphdr - (u8_t *)seg->p->payload);
|
---|
1549 | if (len == 0) {
|
---|
1550 | /** Exclude retransmitted segments from this count. */
|
---|
1551 | MIB2_STATS_INC(mib2.tcpoutsegs);
|
---|
1552 | }
|
---|
1553 |
|
---|
1554 | seg->p->len -= len;
|
---|
1555 | seg->p->tot_len -= len;
|
---|
1556 |
|
---|
1557 | seg->p->payload = seg->tcphdr;
|
---|
1558 |
|
---|
1559 | seg->tcphdr->chksum = 0;
|
---|
1560 |
|
---|
1561 | #ifdef LWIP_HOOK_TCP_OUT_ADD_TCPOPTS
|
---|
1562 | opts = LWIP_HOOK_TCP_OUT_ADD_TCPOPTS(seg->p, seg->tcphdr, pcb, opts);
|
---|
1563 | #endif
|
---|
1564 | LWIP_ASSERT("options not filled", (u8_t *)opts == ((u8_t *)(seg->tcphdr + 1)) + LWIP_TCP_OPT_LENGTH_SEGMENT(seg->flags, pcb));
|
---|
1565 |
|
---|
1566 | #if CHECKSUM_GEN_TCP
|
---|
1567 | IF__NETIF_CHECKSUM_ENABLED(netif, NETIF_CHECKSUM_GEN_TCP) {
|
---|
1568 | #if TCP_CHECKSUM_ON_COPY
|
---|
1569 | u32_t acc;
|
---|
1570 | #if TCP_CHECKSUM_ON_COPY_SANITY_CHECK
|
---|
1571 | u16_t chksum_slow = ip_chksum_pseudo(seg->p, IP_PROTO_TCP,
|
---|
1572 | seg->p->tot_len, &pcb->local_ip, &pcb->remote_ip);
|
---|
1573 | #endif /* TCP_CHECKSUM_ON_COPY_SANITY_CHECK */
|
---|
1574 | if ((seg->flags & TF_SEG_DATA_CHECKSUMMED) == 0) {
|
---|
1575 | LWIP_ASSERT("data included but not checksummed",
|
---|
1576 | seg->p->tot_len == TCPH_HDRLEN_BYTES(seg->tcphdr));
|
---|
1577 | }
|
---|
1578 |
|
---|
1579 | /* rebuild TCP header checksum (TCP header changes for retransmissions!) */
|
---|
1580 | acc = ip_chksum_pseudo_partial(seg->p, IP_PROTO_TCP,
|
---|
1581 | seg->p->tot_len, TCPH_HDRLEN_BYTES(seg->tcphdr), &pcb->local_ip, &pcb->remote_ip);
|
---|
1582 | /* add payload checksum */
|
---|
1583 | if (seg->chksum_swapped) {
|
---|
1584 | seg_chksum_was_swapped = 1;
|
---|
1585 | seg->chksum = SWAP_BYTES_IN_WORD(seg->chksum);
|
---|
1586 | seg->chksum_swapped = 0;
|
---|
1587 | }
|
---|
1588 | acc = (u16_t)~acc + seg->chksum;
|
---|
1589 | seg->tcphdr->chksum = (u16_t)~FOLD_U32T(acc);
|
---|
1590 | #if TCP_CHECKSUM_ON_COPY_SANITY_CHECK
|
---|
1591 | if (chksum_slow != seg->tcphdr->chksum) {
|
---|
1592 | TCP_CHECKSUM_ON_COPY_SANITY_CHECK_FAIL(
|
---|
1593 | ("tcp_output_segment: calculated checksum is %"X16_F" instead of %"X16_F"\n",
|
---|
1594 | seg->tcphdr->chksum, chksum_slow));
|
---|
1595 | seg->tcphdr->chksum = chksum_slow;
|
---|
1596 | }
|
---|
1597 | #endif /* TCP_CHECKSUM_ON_COPY_SANITY_CHECK */
|
---|
1598 | #else /* TCP_CHECKSUM_ON_COPY */
|
---|
1599 | seg->tcphdr->chksum = ip_chksum_pseudo(seg->p, IP_PROTO_TCP,
|
---|
1600 | seg->p->tot_len, &pcb->local_ip, &pcb->remote_ip);
|
---|
1601 | #endif /* TCP_CHECKSUM_ON_COPY */
|
---|
1602 | }
|
---|
1603 | #endif /* CHECKSUM_GEN_TCP */
|
---|
1604 | TCP_STATS_INC(tcp.xmit);
|
---|
1605 |
|
---|
1606 | NETIF_SET_HINTS(netif, &(pcb->netif_hints));
|
---|
1607 | err = ip_output_if(seg->p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl,
|
---|
1608 | pcb->tos, IP_PROTO_TCP, netif);
|
---|
1609 | NETIF_RESET_HINTS(netif);
|
---|
1610 |
|
---|
1611 | #if TCP_CHECKSUM_ON_COPY
|
---|
1612 | if (seg_chksum_was_swapped) {
|
---|
1613 | /* if data is added to this segment later, chksum needs to be swapped,
|
---|
1614 | so restore this now */
|
---|
1615 | seg->chksum = SWAP_BYTES_IN_WORD(seg->chksum);
|
---|
1616 | seg->chksum_swapped = 1;
|
---|
1617 | }
|
---|
1618 | #endif
|
---|
1619 |
|
---|
1620 | return err;
|
---|
1621 | }
|
---|
1622 |
|
---|
1623 | /**
|
---|
1624 | * Requeue all unacked segments for retransmission
|
---|
1625 | *
|
---|
1626 | * Called by tcp_slowtmr() for slow retransmission.
|
---|
1627 | *
|
---|
1628 | * @param pcb the tcp_pcb for which to re-enqueue all unacked segments
|
---|
1629 | */
|
---|
1630 | err_t
|
---|
1631 | tcp_rexmit_rto_prepare(struct tcp_pcb *pcb)
|
---|
1632 | {
|
---|
1633 | struct tcp_seg *seg;
|
---|
1634 |
|
---|
1635 | LWIP_ASSERT("tcp_rexmit_rto_prepare: invalid pcb", pcb != NULL);
|
---|
1636 |
|
---|
1637 | if (pcb->unacked == NULL) {
|
---|
1638 | return ERR_VAL;
|
---|
1639 | }
|
---|
1640 |
|
---|
1641 | /* Move all unacked segments to the head of the unsent queue.
|
---|
1642 | However, give up if any of the unsent pbufs are still referenced by the
|
---|
1643 | netif driver due to deferred transmission. No point loading the link further
|
---|
1644 | if it is struggling to flush its buffered writes. */
|
---|
1645 | for (seg = pcb->unacked; seg->next != NULL; seg = seg->next) {
|
---|
1646 | if (tcp_output_segment_busy(seg)) {
|
---|
1647 | LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_rexmit_rto: segment busy\n"));
|
---|
1648 | return ERR_VAL;
|
---|
1649 | }
|
---|
1650 | }
|
---|
1651 | if (tcp_output_segment_busy(seg)) {
|
---|
1652 | LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_rexmit_rto: segment busy\n"));
|
---|
1653 | return ERR_VAL;
|
---|
1654 | }
|
---|
1655 | /* concatenate unsent queue after unacked queue */
|
---|
1656 | seg->next = pcb->unsent;
|
---|
1657 | #if TCP_OVERSIZE_DBGCHECK
|
---|
1658 | /* if last unsent changed, we need to update unsent_oversize */
|
---|
1659 | if (pcb->unsent == NULL) {
|
---|
1660 | pcb->unsent_oversize = seg->oversize_left;
|
---|
1661 | }
|
---|
1662 | #endif /* TCP_OVERSIZE_DBGCHECK */
|
---|
1663 | /* unsent queue is the concatenated queue (of unacked, unsent) */
|
---|
1664 | pcb->unsent = pcb->unacked;
|
---|
1665 | /* unacked queue is now empty */
|
---|
1666 | pcb->unacked = NULL;
|
---|
1667 |
|
---|
1668 | /* Mark RTO in-progress */
|
---|
1669 | tcp_set_flags(pcb, TF_RTO);
|
---|
1670 | /* Record the next byte following retransmit */
|
---|
1671 | pcb->rto_end = lwip_ntohl(seg->tcphdr->seqno) + TCP_TCPLEN(seg);
|
---|
1672 | /* Don't take any RTT measurements after retransmitting. */
|
---|
1673 | pcb->rttest = 0;
|
---|
1674 |
|
---|
1675 | return ERR_OK;
|
---|
1676 | }
|
---|
1677 |
|
---|
1678 | /**
|
---|
1679 | * Requeue all unacked segments for retransmission
|
---|
1680 | *
|
---|
1681 | * Called by tcp_slowtmr() for slow retransmission.
|
---|
1682 | *
|
---|
1683 | * @param pcb the tcp_pcb for which to re-enqueue all unacked segments
|
---|
1684 | */
|
---|
1685 | void
|
---|
1686 | tcp_rexmit_rto_commit(struct tcp_pcb *pcb)
|
---|
1687 | {
|
---|
1688 | LWIP_ASSERT("tcp_rexmit_rto_commit: invalid pcb", pcb != NULL);
|
---|
1689 |
|
---|
1690 | /* increment number of retransmissions */
|
---|
1691 | if (pcb->nrtx < 0xFF) {
|
---|
1692 | ++pcb->nrtx;
|
---|
1693 | }
|
---|
1694 | /* Do the actual retransmission */
|
---|
1695 | tcp_output(pcb);
|
---|
1696 | }
|
---|
1697 |
|
---|
1698 | /**
|
---|
1699 | * Requeue all unacked segments for retransmission
|
---|
1700 | *
|
---|
1701 | * Called by tcp_process() only, tcp_slowtmr() needs to do some things between
|
---|
1702 | * "prepare" and "commit".
|
---|
1703 | *
|
---|
1704 | * @param pcb the tcp_pcb for which to re-enqueue all unacked segments
|
---|
1705 | */
|
---|
1706 | void
|
---|
1707 | tcp_rexmit_rto(struct tcp_pcb *pcb)
|
---|
1708 | {
|
---|
1709 | LWIP_ASSERT("tcp_rexmit_rto: invalid pcb", pcb != NULL);
|
---|
1710 |
|
---|
1711 | if (tcp_rexmit_rto_prepare(pcb) == ERR_OK) {
|
---|
1712 | tcp_rexmit_rto_commit(pcb);
|
---|
1713 | }
|
---|
1714 | }
|
---|
1715 |
|
---|
1716 | /**
|
---|
1717 | * Requeue the first unacked segment for retransmission
|
---|
1718 | *
|
---|
1719 | * Called by tcp_receive() for fast retransmit.
|
---|
1720 | *
|
---|
1721 | * @param pcb the tcp_pcb for which to retransmit the first unacked segment
|
---|
1722 | */
|
---|
1723 | err_t
|
---|
1724 | tcp_rexmit(struct tcp_pcb *pcb)
|
---|
1725 | {
|
---|
1726 | struct tcp_seg *seg;
|
---|
1727 | struct tcp_seg **cur_seg;
|
---|
1728 |
|
---|
1729 | LWIP_ASSERT("tcp_rexmit: invalid pcb", pcb != NULL);
|
---|
1730 |
|
---|
1731 | if (pcb->unacked == NULL) {
|
---|
1732 | return ERR_VAL;
|
---|
1733 | }
|
---|
1734 |
|
---|
1735 | seg = pcb->unacked;
|
---|
1736 |
|
---|
1737 | /* Give up if the segment is still referenced by the netif driver
|
---|
1738 | due to deferred transmission. */
|
---|
1739 | if (tcp_output_segment_busy(seg)) {
|
---|
1740 | LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_rexmit busy\n"));
|
---|
1741 | return ERR_VAL;
|
---|
1742 | }
|
---|
1743 |
|
---|
1744 | /* Move the first unacked segment to the unsent queue */
|
---|
1745 | /* Keep the unsent queue sorted. */
|
---|
1746 | pcb->unacked = seg->next;
|
---|
1747 |
|
---|
1748 | cur_seg = &(pcb->unsent);
|
---|
1749 | while (*cur_seg &&
|
---|
1750 | TCP_SEQ_LT(lwip_ntohl((*cur_seg)->tcphdr->seqno), lwip_ntohl(seg->tcphdr->seqno))) {
|
---|
1751 | cur_seg = &((*cur_seg)->next );
|
---|
1752 | }
|
---|
1753 | seg->next = *cur_seg;
|
---|
1754 | *cur_seg = seg;
|
---|
1755 | #if TCP_OVERSIZE
|
---|
1756 | if (seg->next == NULL) {
|
---|
1757 | /* the retransmitted segment is last in unsent, so reset unsent_oversize */
|
---|
1758 | pcb->unsent_oversize = 0;
|
---|
1759 | }
|
---|
1760 | #endif /* TCP_OVERSIZE */
|
---|
1761 |
|
---|
1762 | if (pcb->nrtx < 0xFF) {
|
---|
1763 | ++pcb->nrtx;
|
---|
1764 | }
|
---|
1765 |
|
---|
1766 | /* Don't take any rtt measurements after retransmitting. */
|
---|
1767 | pcb->rttest = 0;
|
---|
1768 |
|
---|
1769 | /* Do the actual retransmission. */
|
---|
1770 | MIB2_STATS_INC(mib2.tcpretranssegs);
|
---|
1771 | /* No need to call tcp_output: we are always called from tcp_input()
|
---|
1772 | and thus tcp_output directly returns. */
|
---|
1773 | return ERR_OK;
|
---|
1774 | }
|
---|
1775 |
|
---|
1776 |
|
---|
1777 | /**
|
---|
1778 | * Handle retransmission after three dupacks received
|
---|
1779 | *
|
---|
1780 | * @param pcb the tcp_pcb for which to retransmit the first unacked segment
|
---|
1781 | */
|
---|
1782 | void
|
---|
1783 | tcp_rexmit_fast(struct tcp_pcb *pcb)
|
---|
1784 | {
|
---|
1785 | LWIP_ASSERT("tcp_rexmit_fast: invalid pcb", pcb != NULL);
|
---|
1786 |
|
---|
1787 | if (pcb->unacked != NULL && !(pcb->flags & TF_INFR)) {
|
---|
1788 | /* This is fast retransmit. Retransmit the first unacked segment. */
|
---|
1789 | LWIP_DEBUGF(TCP_FR_DEBUG,
|
---|
1790 | ("tcp_receive: dupacks %"U16_F" (%"U32_F
|
---|
1791 | "), fast retransmit %"U32_F"\n",
|
---|
1792 | (u16_t)pcb->dupacks, pcb->lastack,
|
---|
1793 | lwip_ntohl(pcb->unacked->tcphdr->seqno)));
|
---|
1794 | if (tcp_rexmit(pcb) == ERR_OK) {
|
---|
1795 | /* Set ssthresh to half of the minimum of the current
|
---|
1796 | * cwnd and the advertised window */
|
---|
1797 | pcb->ssthresh = LWIP_MIN(pcb->cwnd, pcb->snd_wnd) / 2;
|
---|
1798 |
|
---|
1799 | /* The minimum value for ssthresh should be 2 MSS */
|
---|
1800 | if (pcb->ssthresh < (2U * pcb->mss)) {
|
---|
1801 | LWIP_DEBUGF(TCP_FR_DEBUG,
|
---|
1802 | ("tcp_receive: The minimum value for ssthresh %"TCPWNDSIZE_F
|
---|
1803 | " should be min 2 mss %"U16_F"...\n",
|
---|
1804 | pcb->ssthresh, (u16_t)(2 * pcb->mss)));
|
---|
1805 | pcb->ssthresh = 2 * pcb->mss;
|
---|
1806 | }
|
---|
1807 |
|
---|
1808 | pcb->cwnd = pcb->ssthresh + 3 * pcb->mss;
|
---|
1809 | tcp_set_flags(pcb, TF_INFR);
|
---|
1810 |
|
---|
1811 | /* Reset the retransmission timer to prevent immediate rto retransmissions */
|
---|
1812 | pcb->rtime = 0;
|
---|
1813 | }
|
---|
1814 | }
|
---|
1815 | }
|
---|
1816 |
|
---|
1817 | static struct pbuf *
|
---|
1818 | tcp_output_alloc_header_common(u32_t ackno, u16_t optlen, u16_t datalen,
|
---|
1819 | u32_t seqno_be /* already in network byte order */,
|
---|
1820 | u16_t src_port, u16_t dst_port, u8_t flags, u16_t wnd)
|
---|
1821 | {
|
---|
1822 | struct tcp_hdr *tcphdr;
|
---|
1823 | struct pbuf *p;
|
---|
1824 |
|
---|
1825 | p = pbuf_alloc(PBUF_IP, TCP_HLEN + optlen + datalen, PBUF_RAM);
|
---|
1826 | if (p != NULL) {
|
---|
1827 | LWIP_ASSERT("check that first pbuf can hold struct tcp_hdr",
|
---|
1828 | (p->len >= TCP_HLEN + optlen));
|
---|
1829 | tcphdr = (struct tcp_hdr *)p->payload;
|
---|
1830 | tcphdr->src = lwip_htons(src_port);
|
---|
1831 | tcphdr->dest = lwip_htons(dst_port);
|
---|
1832 | tcphdr->seqno = seqno_be;
|
---|
1833 | tcphdr->ackno = lwip_htonl(ackno);
|
---|
1834 | TCPH_HDRLEN_FLAGS_SET(tcphdr, (5 + optlen / 4), flags);
|
---|
1835 | tcphdr->wnd = lwip_htons(wnd);
|
---|
1836 | tcphdr->chksum = 0;
|
---|
1837 | tcphdr->urgp = 0;
|
---|
1838 | }
|
---|
1839 | return p;
|
---|
1840 | }
|
---|
1841 |
|
---|
1842 | /** Allocate a pbuf and create a tcphdr at p->payload, used for output
|
---|
1843 | * functions other than the default tcp_output -> tcp_output_segment
|
---|
1844 | * (e.g. tcp_send_empty_ack, etc.)
|
---|
1845 | *
|
---|
1846 | * @param pcb tcp pcb for which to send a packet (used to initialize tcp_hdr)
|
---|
1847 | * @param optlen length of header-options
|
---|
1848 | * @param datalen length of tcp data to reserve in pbuf
|
---|
1849 | * @param seqno_be seqno in network byte order (big-endian)
|
---|
1850 | * @return pbuf with p->payload being the tcp_hdr
|
---|
1851 | */
|
---|
1852 | static struct pbuf *
|
---|
1853 | tcp_output_alloc_header(struct tcp_pcb *pcb, u16_t optlen, u16_t datalen,
|
---|
1854 | u32_t seqno_be /* already in network byte order */)
|
---|
1855 | {
|
---|
1856 | struct pbuf *p;
|
---|
1857 |
|
---|
1858 | LWIP_ASSERT("tcp_output_alloc_header: invalid pcb", pcb != NULL);
|
---|
1859 |
|
---|
1860 | p = tcp_output_alloc_header_common(pcb->rcv_nxt, optlen, datalen,
|
---|
1861 | seqno_be, pcb->local_port, pcb->remote_port, TCP_ACK,
|
---|
1862 | TCPWND_MIN16(RCV_WND_SCALE(pcb, pcb->rcv_ann_wnd)));
|
---|
1863 | if (p != NULL) {
|
---|
1864 | /* If we're sending a packet, update the announced right window edge */
|
---|
1865 | pcb->rcv_ann_right_edge = pcb->rcv_nxt + pcb->rcv_ann_wnd;
|
---|
1866 | }
|
---|
1867 | return p;
|
---|
1868 | }
|
---|
1869 |
|
---|
1870 | /* Fill in options for control segments */
|
---|
1871 | static void
|
---|
1872 | tcp_output_fill_options(const struct tcp_pcb *pcb, struct pbuf *p, u8_t optflags, u8_t num_sacks)
|
---|
1873 | {
|
---|
1874 | struct tcp_hdr *tcphdr;
|
---|
1875 | u32_t *opts;
|
---|
1876 | u16_t sacks_len = 0;
|
---|
1877 |
|
---|
1878 | LWIP_ASSERT("tcp_output_fill_options: invalid pbuf", p != NULL);
|
---|
1879 |
|
---|
1880 | tcphdr = (struct tcp_hdr *)p->payload;
|
---|
1881 | opts = (u32_t *)(void *)(tcphdr + 1);
|
---|
1882 |
|
---|
1883 | /* NB. MSS and window scale options are only sent on SYNs, so ignore them here */
|
---|
1884 |
|
---|
1885 | #if LWIP_TCP_TIMESTAMPS
|
---|
1886 | if (optflags & TF_SEG_OPTS_TS) {
|
---|
1887 | tcp_build_timestamp_option(pcb, opts);
|
---|
1888 | opts += 3;
|
---|
1889 | }
|
---|
1890 | #endif
|
---|
1891 |
|
---|
1892 | #if LWIP_TCP_SACK_OUT
|
---|
1893 | if (pcb && (num_sacks > 0)) {
|
---|
1894 | tcp_build_sack_option(pcb, opts, num_sacks);
|
---|
1895 | /* 1 word for SACKs header (including 2xNOP), and 2 words for each SACK */
|
---|
1896 | sacks_len = 1 + num_sacks * 2;
|
---|
1897 | opts += sacks_len;
|
---|
1898 | }
|
---|
1899 | #else
|
---|
1900 | LWIP_UNUSED_ARG(num_sacks);
|
---|
1901 | #endif
|
---|
1902 |
|
---|
1903 | #ifdef LWIP_HOOK_TCP_OUT_ADD_TCPOPTS
|
---|
1904 | opts = LWIP_HOOK_TCP_OUT_ADD_TCPOPTS(p, tcphdr, pcb, opts);
|
---|
1905 | #endif
|
---|
1906 |
|
---|
1907 | LWIP_UNUSED_ARG(pcb);
|
---|
1908 | LWIP_UNUSED_ARG(sacks_len);
|
---|
1909 | LWIP_ASSERT("options not filled", (u8_t *)opts == ((u8_t *)(tcphdr + 1)) + sacks_len * 4 + LWIP_TCP_OPT_LENGTH_SEGMENT(optflags, pcb));
|
---|
1910 | LWIP_UNUSED_ARG(optflags); /* for LWIP_NOASSERT */
|
---|
1911 | LWIP_UNUSED_ARG(opts); /* for LWIP_NOASSERT */
|
---|
1912 | }
|
---|
1913 |
|
---|
1914 | /** Output a control segment pbuf to IP.
|
---|
1915 | *
|
---|
1916 | * Called from tcp_rst, tcp_send_empty_ack, tcp_keepalive and tcp_zero_window_probe,
|
---|
1917 | * this function combines selecting a netif for transmission, generating the tcp
|
---|
1918 | * header checksum and calling ip_output_if while handling netif hints and stats.
|
---|
1919 | */
|
---|
1920 | static err_t
|
---|
1921 | tcp_output_control_segment(const struct tcp_pcb *pcb, struct pbuf *p,
|
---|
1922 | const ip_addr_t *src, const ip_addr_t *dst)
|
---|
1923 | {
|
---|
1924 | err_t err;
|
---|
1925 | struct netif *netif;
|
---|
1926 |
|
---|
1927 | LWIP_ASSERT("tcp_output_control_segment: invalid pbuf", p != NULL);
|
---|
1928 |
|
---|
1929 | netif = tcp_route(pcb, src, dst);
|
---|
1930 | if (netif == NULL) {
|
---|
1931 | err = ERR_RTE;
|
---|
1932 | } else {
|
---|
1933 | u8_t ttl, tos;
|
---|
1934 | #if CHECKSUM_GEN_TCP
|
---|
1935 | IF__NETIF_CHECKSUM_ENABLED(netif, NETIF_CHECKSUM_GEN_TCP) {
|
---|
1936 | struct tcp_hdr *tcphdr = (struct tcp_hdr *)p->payload;
|
---|
1937 | tcphdr->chksum = ip_chksum_pseudo(p, IP_PROTO_TCP, p->tot_len,
|
---|
1938 | src, dst);
|
---|
1939 | }
|
---|
1940 | #endif
|
---|
1941 | if (pcb != NULL) {
|
---|
1942 | NETIF_SET_HINTS(netif, LWIP_CONST_CAST(struct netif_hint*, &(pcb->netif_hints)));
|
---|
1943 | ttl = pcb->ttl;
|
---|
1944 | tos = pcb->tos;
|
---|
1945 | } else {
|
---|
1946 | /* Send output with hardcoded TTL/HL since we have no access to the pcb */
|
---|
1947 | ttl = TCP_TTL;
|
---|
1948 | tos = 0;
|
---|
1949 | }
|
---|
1950 | TCP_STATS_INC(tcp.xmit);
|
---|
1951 | err = ip_output_if(p, src, dst, ttl, tos, IP_PROTO_TCP, netif);
|
---|
1952 | NETIF_RESET_HINTS(netif);
|
---|
1953 | }
|
---|
1954 | pbuf_free(p);
|
---|
1955 | return err;
|
---|
1956 | }
|
---|
1957 |
|
---|
1958 | /**
|
---|
1959 | * Send a TCP RESET packet (empty segment with RST flag set) either to
|
---|
1960 | * abort a connection or to show that there is no matching local connection
|
---|
1961 | * for a received segment.
|
---|
1962 | *
|
---|
1963 | * Called by tcp_abort() (to abort a local connection), tcp_input() (if no
|
---|
1964 | * matching local pcb was found), tcp_listen_input() (if incoming segment
|
---|
1965 | * has ACK flag set) and tcp_process() (received segment in the wrong state)
|
---|
1966 | *
|
---|
1967 | * Since a RST segment is in most cases not sent for an active connection,
|
---|
1968 | * tcp_rst() has a number of arguments that are taken from a tcp_pcb for
|
---|
1969 | * most other segment output functions.
|
---|
1970 | *
|
---|
1971 | * @param pcb TCP pcb (may be NULL if no pcb is available)
|
---|
1972 | * @param seqno the sequence number to use for the outgoing segment
|
---|
1973 | * @param ackno the acknowledge number to use for the outgoing segment
|
---|
1974 | * @param local_ip the local IP address to send the segment from
|
---|
1975 | * @param remote_ip the remote IP address to send the segment to
|
---|
1976 | * @param local_port the local TCP port to send the segment from
|
---|
1977 | * @param remote_port the remote TCP port to send the segment to
|
---|
1978 | */
|
---|
1979 | void
|
---|
1980 | tcp_rst(const struct tcp_pcb *pcb, u32_t seqno, u32_t ackno,
|
---|
1981 | const ip_addr_t *local_ip, const ip_addr_t *remote_ip,
|
---|
1982 | u16_t local_port, u16_t remote_port)
|
---|
1983 | {
|
---|
1984 | struct pbuf *p;
|
---|
1985 | u16_t wnd;
|
---|
1986 | u8_t optlen;
|
---|
1987 |
|
---|
1988 | LWIP_ASSERT("tcp_rst: invalid local_ip", local_ip != NULL);
|
---|
1989 | LWIP_ASSERT("tcp_rst: invalid remote_ip", remote_ip != NULL);
|
---|
1990 |
|
---|
1991 | optlen = LWIP_TCP_OPT_LENGTH_SEGMENT(0, pcb);
|
---|
1992 |
|
---|
1993 | #if LWIP_WND_SCALE
|
---|
1994 | wnd = PP_HTONS(((TCP_WND >> TCP_RCV_SCALE) & 0xFFFF));
|
---|
1995 | #else
|
---|
1996 | wnd = PP_HTONS(TCP_WND);
|
---|
1997 | #endif
|
---|
1998 |
|
---|
1999 | p = tcp_output_alloc_header_common(ackno, optlen, 0, lwip_htonl(seqno), local_port,
|
---|
2000 | remote_port, TCP_RST | TCP_ACK, wnd);
|
---|
2001 | if (p == NULL) {
|
---|
2002 | LWIP_DEBUGF(TCP_DEBUG, ("tcp_rst: could not allocate memory for pbuf\n"));
|
---|
2003 | return;
|
---|
2004 | }
|
---|
2005 | tcp_output_fill_options(pcb, p, 0, optlen);
|
---|
2006 |
|
---|
2007 | MIB2_STATS_INC(mib2.tcpoutrsts);
|
---|
2008 |
|
---|
2009 | tcp_output_control_segment(pcb, p, local_ip, remote_ip);
|
---|
2010 | LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_rst: seqno %"U32_F" ackno %"U32_F".\n", seqno, ackno));
|
---|
2011 | }
|
---|
2012 |
|
---|
2013 | /**
|
---|
2014 | * Send an ACK without data.
|
---|
2015 | *
|
---|
2016 | * @param pcb Protocol control block for the TCP connection to send the ACK
|
---|
2017 | */
|
---|
2018 | err_t
|
---|
2019 | tcp_send_empty_ack(struct tcp_pcb *pcb)
|
---|
2020 | {
|
---|
2021 | err_t err;
|
---|
2022 | struct pbuf *p;
|
---|
2023 | u8_t optlen, optflags = 0;
|
---|
2024 | u8_t num_sacks = 0;
|
---|
2025 |
|
---|
2026 | LWIP_ASSERT("tcp_send_empty_ack: invalid pcb", pcb != NULL);
|
---|
2027 |
|
---|
2028 | #if LWIP_TCP_TIMESTAMPS
|
---|
2029 | if (pcb->flags & TF_TIMESTAMP) {
|
---|
2030 | optflags = TF_SEG_OPTS_TS;
|
---|
2031 | }
|
---|
2032 | #endif
|
---|
2033 | optlen = LWIP_TCP_OPT_LENGTH_SEGMENT(optflags, pcb);
|
---|
2034 |
|
---|
2035 | #if LWIP_TCP_SACK_OUT
|
---|
2036 | /* For now, SACKs are only sent with empty ACKs */
|
---|
2037 | if ((num_sacks = tcp_get_num_sacks(pcb, optlen)) > 0) {
|
---|
2038 | optlen += 4 + num_sacks * 8; /* 4 bytes for header (including 2*NOP), plus 8B for each SACK */
|
---|
2039 | }
|
---|
2040 | #endif
|
---|
2041 |
|
---|
2042 | p = tcp_output_alloc_header(pcb, optlen, 0, lwip_htonl(pcb->snd_nxt));
|
---|
2043 | if (p == NULL) {
|
---|
2044 | /* let tcp_fasttmr retry sending this ACK */
|
---|
2045 | tcp_set_flags(pcb, TF_ACK_DELAY | TF_ACK_NOW);
|
---|
2046 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output: (ACK) could not allocate pbuf\n"));
|
---|
2047 | return ERR_BUF;
|
---|
2048 | }
|
---|
2049 | tcp_output_fill_options(pcb, p, optflags, num_sacks);
|
---|
2050 |
|
---|
2051 | #if LWIP_TCP_TIMESTAMPS
|
---|
2052 | pcb->ts_lastacksent = pcb->rcv_nxt;
|
---|
2053 | #endif
|
---|
2054 |
|
---|
2055 | LWIP_DEBUGF(TCP_OUTPUT_DEBUG,
|
---|
2056 | ("tcp_output: sending ACK for %"U32_F"\n", pcb->rcv_nxt));
|
---|
2057 | err = tcp_output_control_segment(pcb, p, &pcb->local_ip, &pcb->remote_ip);
|
---|
2058 | if (err != ERR_OK) {
|
---|
2059 | /* let tcp_fasttmr retry sending this ACK */
|
---|
2060 | tcp_set_flags(pcb, TF_ACK_DELAY | TF_ACK_NOW);
|
---|
2061 | } else {
|
---|
2062 | /* remove ACK flags from the PCB, as we sent an empty ACK now */
|
---|
2063 | tcp_clear_flags(pcb, TF_ACK_DELAY | TF_ACK_NOW);
|
---|
2064 | }
|
---|
2065 |
|
---|
2066 | return err;
|
---|
2067 | }
|
---|
2068 |
|
---|
2069 | /**
|
---|
2070 | * Send keepalive packets to keep a connection active although
|
---|
2071 | * no data is sent over it.
|
---|
2072 | *
|
---|
2073 | * Called by tcp_slowtmr()
|
---|
2074 | *
|
---|
2075 | * @param pcb the tcp_pcb for which to send a keepalive packet
|
---|
2076 | */
|
---|
2077 | err_t
|
---|
2078 | tcp_keepalive(struct tcp_pcb *pcb)
|
---|
2079 | {
|
---|
2080 | err_t err;
|
---|
2081 | struct pbuf *p;
|
---|
2082 | u8_t optlen = LWIP_TCP_OPT_LENGTH_SEGMENT(0, pcb);
|
---|
2083 |
|
---|
2084 | LWIP_ASSERT("tcp_keepalive: invalid pcb", pcb != NULL);
|
---|
2085 |
|
---|
2086 | LWIP_DEBUGF(TCP_DEBUG, ("tcp_keepalive: sending KEEPALIVE probe to "));
|
---|
2087 | ip_addr_debug_print_val(TCP_DEBUG, pcb->remote_ip);
|
---|
2088 | LWIP_DEBUGF(TCP_DEBUG, ("\n"));
|
---|
2089 |
|
---|
2090 | LWIP_DEBUGF(TCP_DEBUG, ("tcp_keepalive: tcp_ticks %"U32_F" pcb->tmr %"U32_F" pcb->keep_cnt_sent %"U16_F"\n",
|
---|
2091 | tcp_ticks, pcb->tmr, (u16_t)pcb->keep_cnt_sent));
|
---|
2092 |
|
---|
2093 | p = tcp_output_alloc_header(pcb, optlen, 0, lwip_htonl(pcb->snd_nxt - 1));
|
---|
2094 | if (p == NULL) {
|
---|
2095 | LWIP_DEBUGF(TCP_DEBUG,
|
---|
2096 | ("tcp_keepalive: could not allocate memory for pbuf\n"));
|
---|
2097 | return ERR_MEM;
|
---|
2098 | }
|
---|
2099 | tcp_output_fill_options(pcb, p, 0, optlen);
|
---|
2100 | err = tcp_output_control_segment(pcb, p, &pcb->local_ip, &pcb->remote_ip);
|
---|
2101 |
|
---|
2102 | LWIP_DEBUGF(TCP_DEBUG, ("tcp_keepalive: seqno %"U32_F" ackno %"U32_F" err %d.\n",
|
---|
2103 | pcb->snd_nxt - 1, pcb->rcv_nxt, (int)err));
|
---|
2104 | return err;
|
---|
2105 | }
|
---|
2106 |
|
---|
2107 | /**
|
---|
2108 | * Send persist timer zero-window probes to keep a connection active
|
---|
2109 | * when a window update is lost.
|
---|
2110 | *
|
---|
2111 | * Called by tcp_slowtmr()
|
---|
2112 | *
|
---|
2113 | * @param pcb the tcp_pcb for which to send a zero-window probe packet
|
---|
2114 | */
|
---|
2115 | err_t
|
---|
2116 | tcp_zero_window_probe(struct tcp_pcb *pcb)
|
---|
2117 | {
|
---|
2118 | err_t err;
|
---|
2119 | struct pbuf *p;
|
---|
2120 | struct tcp_hdr *tcphdr;
|
---|
2121 | struct tcp_seg *seg;
|
---|
2122 | u16_t len;
|
---|
2123 | u8_t is_fin;
|
---|
2124 | u32_t snd_nxt;
|
---|
2125 | u8_t optlen = LWIP_TCP_OPT_LENGTH_SEGMENT(0, pcb);
|
---|
2126 |
|
---|
2127 | LWIP_ASSERT("tcp_zero_window_probe: invalid pcb", pcb != NULL);
|
---|
2128 |
|
---|
2129 | LWIP_DEBUGF(TCP_DEBUG, ("tcp_zero_window_probe: sending ZERO WINDOW probe to "));
|
---|
2130 | ip_addr_debug_print_val(TCP_DEBUG, pcb->remote_ip);
|
---|
2131 | LWIP_DEBUGF(TCP_DEBUG, ("\n"));
|
---|
2132 |
|
---|
2133 | LWIP_DEBUGF(TCP_DEBUG,
|
---|
2134 | ("tcp_zero_window_probe: tcp_ticks %"U32_F
|
---|
2135 | " pcb->tmr %"U32_F" pcb->keep_cnt_sent %"U16_F"\n",
|
---|
2136 | tcp_ticks, pcb->tmr, (u16_t)pcb->keep_cnt_sent));
|
---|
2137 |
|
---|
2138 | /* Only consider unsent, persist timer should be off when there is data in-flight */
|
---|
2139 | seg = pcb->unsent;
|
---|
2140 | if (seg == NULL) {
|
---|
2141 | /* Not expected, persist timer should be off when the send buffer is empty */
|
---|
2142 | return ERR_OK;
|
---|
2143 | }
|
---|
2144 |
|
---|
2145 | /* increment probe count. NOTE: we record probe even if it fails
|
---|
2146 | to actually transmit due to an error. This ensures memory exhaustion/
|
---|
2147 | routing problem doesn't leave a zero-window pcb as an indefinite zombie.
|
---|
2148 | RTO mechanism has similar behavior, see pcb->nrtx */
|
---|
2149 | if (pcb->persist_probe < 0xFF) {
|
---|
2150 | ++pcb->persist_probe;
|
---|
2151 | }
|
---|
2152 |
|
---|
2153 | is_fin = ((TCPH_FLAGS(seg->tcphdr) & TCP_FIN) != 0) && (seg->len == 0);
|
---|
2154 | /* we want to send one seqno: either FIN or data (no options) */
|
---|
2155 | len = is_fin ? 0 : 1;
|
---|
2156 |
|
---|
2157 | p = tcp_output_alloc_header(pcb, optlen, len, seg->tcphdr->seqno);
|
---|
2158 | if (p == NULL) {
|
---|
2159 | LWIP_DEBUGF(TCP_DEBUG, ("tcp_zero_window_probe: no memory for pbuf\n"));
|
---|
2160 | return ERR_MEM;
|
---|
2161 | }
|
---|
2162 | tcphdr = (struct tcp_hdr *)p->payload;
|
---|
2163 |
|
---|
2164 | if (is_fin) {
|
---|
2165 | /* FIN segment, no data */
|
---|
2166 | TCPH_FLAGS_SET(tcphdr, TCP_ACK | TCP_FIN);
|
---|
2167 | } else {
|
---|
2168 | /* Data segment, copy in one byte from the head of the unacked queue */
|
---|
2169 | char *d = ((char *)p->payload + TCP_HLEN);
|
---|
2170 | /* Depending on whether the segment has already been sent (unacked) or not
|
---|
2171 | (unsent), seg->p->payload points to the IP header or TCP header.
|
---|
2172 | Ensure we copy the first TCP data byte: */
|
---|
2173 | pbuf_copy_partial(seg->p, d, 1, seg->p->tot_len - seg->len);
|
---|
2174 | }
|
---|
2175 |
|
---|
2176 | /* The byte may be acknowledged without the window being opened. */
|
---|
2177 | snd_nxt = lwip_ntohl(seg->tcphdr->seqno) + 1;
|
---|
2178 | if (TCP_SEQ_LT(pcb->snd_nxt, snd_nxt)) {
|
---|
2179 | pcb->snd_nxt = snd_nxt;
|
---|
2180 | }
|
---|
2181 | tcp_output_fill_options(pcb, p, 0, optlen);
|
---|
2182 |
|
---|
2183 | err = tcp_output_control_segment(pcb, p, &pcb->local_ip, &pcb->remote_ip);
|
---|
2184 |
|
---|
2185 | LWIP_DEBUGF(TCP_DEBUG, ("tcp_zero_window_probe: seqno %"U32_F
|
---|
2186 | " ackno %"U32_F" err %d.\n",
|
---|
2187 | pcb->snd_nxt - 1, pcb->rcv_nxt, (int)err));
|
---|
2188 | return err;
|
---|
2189 | }
|
---|
2190 | #endif /* LWIP_TCP */
|
---|