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jeremybenn |
/**
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* @file
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* Transmission Control Protocol, incoming traffic
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*
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* The input processing functions of the TCP layer.
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*
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* These functions are generally called in the order (ip_input() ->)
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* tcp_input() -> * tcp_process() -> tcp_receive() (-> application).
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*
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*/
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/*
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* Copyright (c) 2001-2004 Swedish Institute of Computer Science.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without modification,
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* are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
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* SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
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* OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
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* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
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* OF SUCH DAMAGE.
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*
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* This file is part of the lwIP TCP/IP stack.
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*
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* Author: Adam Dunkels <adam@sics.se>
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*
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*/
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#include "lwip/opt.h"
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#if LWIP_TCP /* don't build if not configured for use in lwipopts.h */
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#include "lwip/tcp.h"
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#include "lwip/def.h"
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#include "lwip/ip_addr.h"
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#include "lwip/netif.h"
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#include "lwip/mem.h"
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#include "lwip/memp.h"
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#include "lwip/inet.h"
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#include "lwip/inet_chksum.h"
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#include "lwip/stats.h"
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#include "lwip/snmp.h"
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#include "arch/perf.h"
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/* These variables are global to all functions involved in the input
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processing of TCP segments. They are set by the tcp_input()
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function. */
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static struct tcp_seg inseg;
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static struct tcp_hdr *tcphdr;
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static struct ip_hdr *iphdr;
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static u32_t seqno, ackno;
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static u8_t flags;
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static u16_t tcplen;
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static u8_t recv_flags;
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static struct pbuf *recv_data;
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struct tcp_pcb *tcp_input_pcb;
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/* Forward declarations. */
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static err_t tcp_process(struct tcp_pcb *pcb);
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static void tcp_receive(struct tcp_pcb *pcb);
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static void tcp_parseopt(struct tcp_pcb *pcb);
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static err_t tcp_listen_input(struct tcp_pcb_listen *pcb);
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static err_t tcp_timewait_input(struct tcp_pcb *pcb);
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/**
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* The initial input processing of TCP. It verifies the TCP header, demultiplexes
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* the segment between the PCBs and passes it on to tcp_process(), which implements
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* the TCP finite state machine. This function is called by the IP layer (in
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* ip_input()).
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*
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* @param p received TCP segment to process (p->payload pointing to the IP header)
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* @param inp network interface on which this segment was received
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*/
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void
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tcp_input(struct pbuf *p, struct netif *inp)
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{
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struct tcp_pcb *pcb, *prev;
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struct tcp_pcb_listen *lpcb;
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u8_t hdrlen;
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err_t err;
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PERF_START;
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TCP_STATS_INC(tcp.recv);
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snmp_inc_tcpinsegs();
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iphdr = p->payload;
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tcphdr = (struct tcp_hdr *)((u8_t *)p->payload + IPH_HL(iphdr) * 4);
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#if TCP_INPUT_DEBUG
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tcp_debug_print(tcphdr);
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#endif
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/* remove header from payload */
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if (pbuf_header(p, -((s16_t)(IPH_HL(iphdr) * 4))) || (p->tot_len < sizeof(struct tcp_hdr))) {
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/* drop short packets */
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LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: short packet (%"U16_F" bytes) discarded\n", p->tot_len));
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TCP_STATS_INC(tcp.lenerr);
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TCP_STATS_INC(tcp.drop);
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snmp_inc_tcpinerrs();
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pbuf_free(p);
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return;
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}
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/* Don't even process incoming broadcasts/multicasts. */
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if (ip_addr_isbroadcast(&(iphdr->dest), inp) ||
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ip_addr_ismulticast(&(iphdr->dest))) {
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TCP_STATS_INC(tcp.proterr);
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TCP_STATS_INC(tcp.drop);
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snmp_inc_tcpinerrs();
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pbuf_free(p);
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return;
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}
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#if CHECKSUM_CHECK_TCP
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/* Verify TCP checksum. */
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if (inet_chksum_pseudo(p, (struct ip_addr *)&(iphdr->src),
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(struct ip_addr *)&(iphdr->dest),
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IP_PROTO_TCP, p->tot_len) != 0) {
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LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packet discarded due to failing checksum 0x%04"X16_F"\n",
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inet_chksum_pseudo(p, (struct ip_addr *)&(iphdr->src), (struct ip_addr *)&(iphdr->dest),
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IP_PROTO_TCP, p->tot_len)));
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#if TCP_DEBUG
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tcp_debug_print(tcphdr);
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#endif /* TCP_DEBUG */
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TCP_STATS_INC(tcp.chkerr);
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TCP_STATS_INC(tcp.drop);
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snmp_inc_tcpinerrs();
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pbuf_free(p);
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return;
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}
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#endif
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/* Move the payload pointer in the pbuf so that it points to the
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TCP data instead of the TCP header. */
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hdrlen = TCPH_HDRLEN(tcphdr);
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if(pbuf_header(p, -(hdrlen * 4))){
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/* drop short packets */
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LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: short packet\n"));
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TCP_STATS_INC(tcp.lenerr);
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TCP_STATS_INC(tcp.drop);
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snmp_inc_tcpinerrs();
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pbuf_free(p);
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return;
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}
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/* Convert fields in TCP header to host byte order. */
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tcphdr->src = ntohs(tcphdr->src);
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tcphdr->dest = ntohs(tcphdr->dest);
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seqno = tcphdr->seqno = ntohl(tcphdr->seqno);
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ackno = tcphdr->ackno = ntohl(tcphdr->ackno);
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tcphdr->wnd = ntohs(tcphdr->wnd);
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flags = TCPH_FLAGS(tcphdr);
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tcplen = p->tot_len + ((flags & (TCP_FIN | TCP_SYN)) ? 1 : 0);
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/* Demultiplex an incoming segment. First, we check if it is destined
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for an active connection. */
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prev = NULL;
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for(pcb = tcp_active_pcbs; pcb != NULL; pcb = pcb->next) {
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LWIP_ASSERT("tcp_input: active pcb->state != CLOSED", pcb->state != CLOSED);
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LWIP_ASSERT("tcp_input: active pcb->state != TIME-WAIT", pcb->state != TIME_WAIT);
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LWIP_ASSERT("tcp_input: active pcb->state != LISTEN", pcb->state != LISTEN);
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if (pcb->remote_port == tcphdr->src &&
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pcb->local_port == tcphdr->dest &&
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ip_addr_cmp(&(pcb->remote_ip), &(iphdr->src)) &&
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ip_addr_cmp(&(pcb->local_ip), &(iphdr->dest))) {
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/* Move this PCB to the front of the list so that subsequent
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lookups will be faster (we exploit locality in TCP segment
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arrivals). */
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LWIP_ASSERT("tcp_input: pcb->next != pcb (before cache)", pcb->next != pcb);
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if (prev != NULL) {
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prev->next = pcb->next;
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pcb->next = tcp_active_pcbs;
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tcp_active_pcbs = pcb;
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}
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LWIP_ASSERT("tcp_input: pcb->next != pcb (after cache)", pcb->next != pcb);
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break;
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}
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prev = pcb;
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}
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if (pcb == NULL) {
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/* If it did not go to an active connection, we check the connections
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in the TIME-WAIT state. */
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for(pcb = tcp_tw_pcbs; pcb != NULL; pcb = pcb->next) {
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LWIP_ASSERT("tcp_input: TIME-WAIT pcb->state == TIME-WAIT", pcb->state == TIME_WAIT);
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if (pcb->remote_port == tcphdr->src &&
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pcb->local_port == tcphdr->dest &&
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ip_addr_cmp(&(pcb->remote_ip), &(iphdr->src)) &&
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ip_addr_cmp(&(pcb->local_ip), &(iphdr->dest))) {
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/* We don't really care enough to move this PCB to the front
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of the list since we are not very likely to receive that
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many segments for connections in TIME-WAIT. */
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LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packed for TIME_WAITing connection.\n"));
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tcp_timewait_input(pcb);
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pbuf_free(p);
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return;
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}
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}
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/* Finally, if we still did not get a match, we check all PCBs that
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are LISTENing for incoming connections. */
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prev = NULL;
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for(lpcb = tcp_listen_pcbs.listen_pcbs; lpcb != NULL; lpcb = lpcb->next) {
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if ((ip_addr_isany(&(lpcb->local_ip)) ||
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ip_addr_cmp(&(lpcb->local_ip), &(iphdr->dest))) &&
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lpcb->local_port == tcphdr->dest) {
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/* Move this PCB to the front of the list so that subsequent
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lookups will be faster (we exploit locality in TCP segment
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arrivals). */
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if (prev != NULL) {
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((struct tcp_pcb_listen *)prev)->next = lpcb->next;
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/* our successor is the remainder of the listening list */
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lpcb->next = tcp_listen_pcbs.listen_pcbs;
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/* put this listening pcb at the head of the listening list */
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tcp_listen_pcbs.listen_pcbs = lpcb;
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}
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LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packed for LISTENing connection.\n"));
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tcp_listen_input(lpcb);
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pbuf_free(p);
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return;
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}
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prev = (struct tcp_pcb *)lpcb;
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}
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}
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#if TCP_INPUT_DEBUG
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LWIP_DEBUGF(TCP_INPUT_DEBUG, ("+-+-+-+-+-+-+-+-+-+-+-+-+-+- tcp_input: flags "));
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tcp_debug_print_flags(TCPH_FLAGS(tcphdr));
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LWIP_DEBUGF(TCP_INPUT_DEBUG, ("-+-+-+-+-+-+-+-+-+-+-+-+-+-+\n"));
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#endif /* TCP_INPUT_DEBUG */
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255 |
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256 |
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if (pcb != NULL) {
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/* The incoming segment belongs to a connection. */
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#if TCP_INPUT_DEBUG
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#if TCP_DEBUG
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tcp_debug_print_state(pcb->state);
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#endif /* TCP_DEBUG */
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#endif /* TCP_INPUT_DEBUG */
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/* Set up a tcp_seg structure. */
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inseg.next = NULL;
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inseg.len = p->tot_len;
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inseg.dataptr = p->payload;
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inseg.p = p;
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inseg.tcphdr = tcphdr;
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271 |
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recv_data = NULL;
|
273 |
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recv_flags = 0;
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274 |
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275 |
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/* If there is data which was previously "refused" by upper layer */
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if (pcb->refused_data != NULL) {
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277 |
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/* Notify again application with data previously received. */
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LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: notify kept packet\n"));
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TCP_EVENT_RECV(pcb, pcb->refused_data, ERR_OK, err);
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280 |
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if (err == ERR_OK) {
|
281 |
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pcb->refused_data = NULL;
|
282 |
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} else {
|
283 |
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/* drop incoming packets, because pcb is "full" */
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284 |
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LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: drop incoming packets, because pcb is \"full\"\n"));
|
285 |
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TCP_STATS_INC(tcp.drop);
|
286 |
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snmp_inc_tcpinerrs();
|
287 |
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pbuf_free(p);
|
288 |
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return;
|
289 |
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}
|
290 |
|
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}
|
291 |
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tcp_input_pcb = pcb;
|
292 |
|
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err = tcp_process(pcb);
|
293 |
|
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/* A return value of ERR_ABRT means that tcp_abort() was called
|
294 |
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and that the pcb has been freed. If so, we don't do anything. */
|
295 |
|
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if (err != ERR_ABRT) {
|
296 |
|
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if (recv_flags & TF_RESET) {
|
297 |
|
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/* TF_RESET means that the connection was reset by the other
|
298 |
|
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end. We then call the error callback to inform the
|
299 |
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application that the connection is dead before we
|
300 |
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deallocate the PCB. */
|
301 |
|
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TCP_EVENT_ERR(pcb->errf, pcb->callback_arg, ERR_RST);
|
302 |
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tcp_pcb_remove(&tcp_active_pcbs, pcb);
|
303 |
|
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memp_free(MEMP_TCP_PCB, pcb);
|
304 |
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} else if (recv_flags & TF_CLOSED) {
|
305 |
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/* The connection has been closed and we will deallocate the
|
306 |
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PCB. */
|
307 |
|
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tcp_pcb_remove(&tcp_active_pcbs, pcb);
|
308 |
|
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memp_free(MEMP_TCP_PCB, pcb);
|
309 |
|
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} else {
|
310 |
|
|
err = ERR_OK;
|
311 |
|
|
/* If the application has registered a "sent" function to be
|
312 |
|
|
called when new send buffer space is available, we call it
|
313 |
|
|
now. */
|
314 |
|
|
if (pcb->acked > 0) {
|
315 |
|
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TCP_EVENT_SENT(pcb, pcb->acked, err);
|
316 |
|
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}
|
317 |
|
|
|
318 |
|
|
if (recv_data != NULL) {
|
319 |
|
|
if(flags & TCP_PSH) {
|
320 |
|
|
recv_data->flags |= PBUF_FLAG_PUSH;
|
321 |
|
|
}
|
322 |
|
|
|
323 |
|
|
/* Notify application that data has been received. */
|
324 |
|
|
TCP_EVENT_RECV(pcb, recv_data, ERR_OK, err);
|
325 |
|
|
|
326 |
|
|
/* If the upper layer can't receive this data, store it */
|
327 |
|
|
if (err != ERR_OK) {
|
328 |
|
|
pcb->refused_data = recv_data;
|
329 |
|
|
LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: keep incoming packet, because pcb is \"full\"\n"));
|
330 |
|
|
}
|
331 |
|
|
}
|
332 |
|
|
|
333 |
|
|
/* If a FIN segment was received, we call the callback
|
334 |
|
|
function with a NULL buffer to indicate EOF. */
|
335 |
|
|
if (recv_flags & TF_GOT_FIN) {
|
336 |
|
|
TCP_EVENT_RECV(pcb, NULL, ERR_OK, err);
|
337 |
|
|
}
|
338 |
|
|
|
339 |
|
|
tcp_input_pcb = NULL;
|
340 |
|
|
/* Try to send something out. */
|
341 |
|
|
tcp_output(pcb);
|
342 |
|
|
#if TCP_INPUT_DEBUG
|
343 |
|
|
#if TCP_DEBUG
|
344 |
|
|
tcp_debug_print_state(pcb->state);
|
345 |
|
|
#endif /* TCP_DEBUG */
|
346 |
|
|
#endif /* TCP_INPUT_DEBUG */
|
347 |
|
|
}
|
348 |
|
|
}
|
349 |
|
|
tcp_input_pcb = NULL;
|
350 |
|
|
|
351 |
|
|
|
352 |
|
|
/* give up our reference to inseg.p */
|
353 |
|
|
if (inseg.p != NULL)
|
354 |
|
|
{
|
355 |
|
|
pbuf_free(inseg.p);
|
356 |
|
|
inseg.p = NULL;
|
357 |
|
|
}
|
358 |
|
|
} else {
|
359 |
|
|
|
360 |
|
|
/* If no matching PCB was found, send a TCP RST (reset) to the
|
361 |
|
|
sender. */
|
362 |
|
|
LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_input: no PCB match found, resetting.\n"));
|
363 |
|
|
if (!(TCPH_FLAGS(tcphdr) & TCP_RST)) {
|
364 |
|
|
TCP_STATS_INC(tcp.proterr);
|
365 |
|
|
TCP_STATS_INC(tcp.drop);
|
366 |
|
|
tcp_rst(ackno, seqno + tcplen,
|
367 |
|
|
&(iphdr->dest), &(iphdr->src),
|
368 |
|
|
tcphdr->dest, tcphdr->src);
|
369 |
|
|
}
|
370 |
|
|
pbuf_free(p);
|
371 |
|
|
}
|
372 |
|
|
|
373 |
|
|
LWIP_ASSERT("tcp_input: tcp_pcbs_sane()", tcp_pcbs_sane());
|
374 |
|
|
PERF_STOP("tcp_input");
|
375 |
|
|
}
|
376 |
|
|
|
377 |
|
|
/**
|
378 |
|
|
* Called by tcp_input() when a segment arrives for a listening
|
379 |
|
|
* connection (from tcp_input()).
|
380 |
|
|
*
|
381 |
|
|
* @param pcb the tcp_pcb_listen for which a segment arrived
|
382 |
|
|
* @return ERR_OK if the segment was processed
|
383 |
|
|
* another err_t on error
|
384 |
|
|
*
|
385 |
|
|
* @note the return value is not (yet?) used in tcp_input()
|
386 |
|
|
* @note the segment which arrived is saved in global variables, therefore only the pcb
|
387 |
|
|
* involved is passed as a parameter to this function
|
388 |
|
|
*/
|
389 |
|
|
static err_t
|
390 |
|
|
tcp_listen_input(struct tcp_pcb_listen *pcb)
|
391 |
|
|
{
|
392 |
|
|
struct tcp_pcb *npcb;
|
393 |
|
|
err_t rc;
|
394 |
|
|
|
395 |
|
|
/* In the LISTEN state, we check for incoming SYN segments,
|
396 |
|
|
creates a new PCB, and responds with a SYN|ACK. */
|
397 |
|
|
if (flags & TCP_ACK) {
|
398 |
|
|
/* For incoming segments with the ACK flag set, respond with a
|
399 |
|
|
RST. */
|
400 |
|
|
LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_listen_input: ACK in LISTEN, sending reset\n"));
|
401 |
|
|
tcp_rst(ackno + 1, seqno + tcplen,
|
402 |
|
|
&(iphdr->dest), &(iphdr->src),
|
403 |
|
|
tcphdr->dest, tcphdr->src);
|
404 |
|
|
} else if (flags & TCP_SYN) {
|
405 |
|
|
LWIP_DEBUGF(TCP_DEBUG, ("TCP connection request %"U16_F" -> %"U16_F".\n", tcphdr->src, tcphdr->dest));
|
406 |
|
|
#if TCP_LISTEN_BACKLOG
|
407 |
|
|
if (pcb->accepts_pending >= pcb->backlog) {
|
408 |
|
|
LWIP_DEBUGF(TCP_DEBUG, ("tcp_listen_input: listen backlog exceeded for port %"U16_F"\n", tcphdr->dest));
|
409 |
|
|
return ERR_ABRT;
|
410 |
|
|
}
|
411 |
|
|
#endif /* TCP_LISTEN_BACKLOG */
|
412 |
|
|
npcb = tcp_alloc(pcb->prio);
|
413 |
|
|
/* If a new PCB could not be created (probably due to lack of memory),
|
414 |
|
|
we don't do anything, but rely on the sender will retransmit the
|
415 |
|
|
SYN at a time when we have more memory available. */
|
416 |
|
|
if (npcb == NULL) {
|
417 |
|
|
LWIP_DEBUGF(TCP_DEBUG, ("tcp_listen_input: could not allocate PCB\n"));
|
418 |
|
|
TCP_STATS_INC(tcp.memerr);
|
419 |
|
|
return ERR_MEM;
|
420 |
|
|
}
|
421 |
|
|
#if TCP_LISTEN_BACKLOG
|
422 |
|
|
pcb->accepts_pending++;
|
423 |
|
|
#endif /* TCP_LISTEN_BACKLOG */
|
424 |
|
|
/* Set up the new PCB. */
|
425 |
|
|
ip_addr_set(&(npcb->local_ip), &(iphdr->dest));
|
426 |
|
|
npcb->local_port = pcb->local_port;
|
427 |
|
|
ip_addr_set(&(npcb->remote_ip), &(iphdr->src));
|
428 |
|
|
npcb->remote_port = tcphdr->src;
|
429 |
|
|
npcb->state = SYN_RCVD;
|
430 |
|
|
npcb->rcv_nxt = seqno + 1;
|
431 |
|
|
npcb->rcv_ann_right_edge = npcb->rcv_nxt;
|
432 |
|
|
npcb->snd_wnd = tcphdr->wnd;
|
433 |
|
|
npcb->ssthresh = npcb->snd_wnd;
|
434 |
|
|
npcb->snd_wl1 = seqno - 1;/* initialise to seqno-1 to force window update */
|
435 |
|
|
npcb->callback_arg = pcb->callback_arg;
|
436 |
|
|
#if LWIP_CALLBACK_API
|
437 |
|
|
npcb->accept = pcb->accept;
|
438 |
|
|
#endif /* LWIP_CALLBACK_API */
|
439 |
|
|
/* inherit socket options */
|
440 |
|
|
npcb->so_options = pcb->so_options & (SOF_DEBUG|SOF_DONTROUTE|SOF_KEEPALIVE|SOF_OOBINLINE|SOF_LINGER);
|
441 |
|
|
/* Register the new PCB so that we can begin receiving segments
|
442 |
|
|
for it. */
|
443 |
|
|
TCP_REG(&tcp_active_pcbs, npcb);
|
444 |
|
|
|
445 |
|
|
/* Parse any options in the SYN. */
|
446 |
|
|
tcp_parseopt(npcb);
|
447 |
|
|
#if TCP_CALCULATE_EFF_SEND_MSS
|
448 |
|
|
npcb->mss = tcp_eff_send_mss(npcb->mss, &(npcb->remote_ip));
|
449 |
|
|
#endif /* TCP_CALCULATE_EFF_SEND_MSS */
|
450 |
|
|
|
451 |
|
|
snmp_inc_tcppassiveopens();
|
452 |
|
|
|
453 |
|
|
/* Send a SYN|ACK together with the MSS option. */
|
454 |
|
|
rc = tcp_enqueue(npcb, NULL, 0, TCP_SYN | TCP_ACK, 0, TF_SEG_OPTS_MSS
|
455 |
|
|
#if LWIP_TCP_TIMESTAMPS
|
456 |
|
|
/* and maybe include the TIMESTAMP option */
|
457 |
|
|
| (npcb->flags & TF_TIMESTAMP ? TF_SEG_OPTS_TS : 0)
|
458 |
|
|
#endif
|
459 |
|
|
);
|
460 |
|
|
if (rc != ERR_OK) {
|
461 |
|
|
tcp_abandon(npcb, 0);
|
462 |
|
|
return rc;
|
463 |
|
|
}
|
464 |
|
|
return tcp_output(npcb);
|
465 |
|
|
}
|
466 |
|
|
return ERR_OK;
|
467 |
|
|
}
|
468 |
|
|
|
469 |
|
|
/**
|
470 |
|
|
* Called by tcp_input() when a segment arrives for a connection in
|
471 |
|
|
* TIME_WAIT.
|
472 |
|
|
*
|
473 |
|
|
* @param pcb the tcp_pcb for which a segment arrived
|
474 |
|
|
*
|
475 |
|
|
* @note the segment which arrived is saved in global variables, therefore only the pcb
|
476 |
|
|
* involved is passed as a parameter to this function
|
477 |
|
|
*/
|
478 |
|
|
static err_t
|
479 |
|
|
tcp_timewait_input(struct tcp_pcb *pcb)
|
480 |
|
|
{
|
481 |
|
|
/* RFC 1337: in TIME_WAIT, ignore RST and ACK FINs + any 'acceptable' segments */
|
482 |
|
|
/* RFC 793 3.9 Event Processing - Segment Arrives:
|
483 |
|
|
* - first check sequence number - we skip that one in TIME_WAIT (always
|
484 |
|
|
* acceptable since we only send ACKs)
|
485 |
|
|
* - second check the RST bit (... return) */
|
486 |
|
|
if (flags & TCP_RST) {
|
487 |
|
|
return ERR_OK;
|
488 |
|
|
}
|
489 |
|
|
/* - fourth, check the SYN bit, */
|
490 |
|
|
if (flags & TCP_SYN) {
|
491 |
|
|
/* If an incoming segment is not acceptable, an acknowledgment
|
492 |
|
|
should be sent in reply */
|
493 |
|
|
if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt, pcb->rcv_nxt+pcb->rcv_wnd)) {
|
494 |
|
|
/* If the SYN is in the window it is an error, send a reset */
|
495 |
|
|
tcp_rst(ackno, seqno + tcplen, &(iphdr->dest), &(iphdr->src),
|
496 |
|
|
tcphdr->dest, tcphdr->src);
|
497 |
|
|
return ERR_OK;
|
498 |
|
|
}
|
499 |
|
|
} else if (flags & TCP_FIN) {
|
500 |
|
|
/* - eighth, check the FIN bit: Remain in the TIME-WAIT state.
|
501 |
|
|
Restart the 2 MSL time-wait timeout.*/
|
502 |
|
|
pcb->tmr = tcp_ticks;
|
503 |
|
|
}
|
504 |
|
|
|
505 |
|
|
if ((tcplen > 0)) {
|
506 |
|
|
/* Acknowledge data, FIN or out-of-window SYN */
|
507 |
|
|
pcb->flags |= TF_ACK_NOW;
|
508 |
|
|
return tcp_output(pcb);
|
509 |
|
|
}
|
510 |
|
|
return ERR_OK;
|
511 |
|
|
}
|
512 |
|
|
|
513 |
|
|
/**
|
514 |
|
|
* Implements the TCP state machine. Called by tcp_input. In some
|
515 |
|
|
* states tcp_receive() is called to receive data. The tcp_seg
|
516 |
|
|
* argument will be freed by the caller (tcp_input()) unless the
|
517 |
|
|
* recv_data pointer in the pcb is set.
|
518 |
|
|
*
|
519 |
|
|
* @param pcb the tcp_pcb for which a segment arrived
|
520 |
|
|
*
|
521 |
|
|
* @note the segment which arrived is saved in global variables, therefore only the pcb
|
522 |
|
|
* involved is passed as a parameter to this function
|
523 |
|
|
*/
|
524 |
|
|
static err_t
|
525 |
|
|
tcp_process(struct tcp_pcb *pcb)
|
526 |
|
|
{
|
527 |
|
|
struct tcp_seg *rseg;
|
528 |
|
|
u8_t acceptable = 0;
|
529 |
|
|
err_t err;
|
530 |
|
|
|
531 |
|
|
err = ERR_OK;
|
532 |
|
|
|
533 |
|
|
/* Process incoming RST segments. */
|
534 |
|
|
if (flags & TCP_RST) {
|
535 |
|
|
/* First, determine if the reset is acceptable. */
|
536 |
|
|
if (pcb->state == SYN_SENT) {
|
537 |
|
|
if (ackno == pcb->snd_nxt) {
|
538 |
|
|
acceptable = 1;
|
539 |
|
|
}
|
540 |
|
|
} else {
|
541 |
|
|
if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt,
|
542 |
|
|
pcb->rcv_nxt+pcb->rcv_wnd)) {
|
543 |
|
|
acceptable = 1;
|
544 |
|
|
}
|
545 |
|
|
}
|
546 |
|
|
|
547 |
|
|
if (acceptable) {
|
548 |
|
|
LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_process: Connection RESET\n"));
|
549 |
|
|
LWIP_ASSERT("tcp_input: pcb->state != CLOSED", pcb->state != CLOSED);
|
550 |
|
|
recv_flags |= TF_RESET;
|
551 |
|
|
pcb->flags &= ~TF_ACK_DELAY;
|
552 |
|
|
return ERR_RST;
|
553 |
|
|
} else {
|
554 |
|
|
LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_process: unacceptable reset seqno %"U32_F" rcv_nxt %"U32_F"\n",
|
555 |
|
|
seqno, pcb->rcv_nxt));
|
556 |
|
|
LWIP_DEBUGF(TCP_DEBUG, ("tcp_process: unacceptable reset seqno %"U32_F" rcv_nxt %"U32_F"\n",
|
557 |
|
|
seqno, pcb->rcv_nxt));
|
558 |
|
|
return ERR_OK;
|
559 |
|
|
}
|
560 |
|
|
}
|
561 |
|
|
|
562 |
|
|
if ((flags & TCP_SYN) && (pcb->state != SYN_SENT && pcb->state != SYN_RCVD)) {
|
563 |
|
|
/* Cope with new connection attempt after remote end crashed */
|
564 |
|
|
tcp_ack_now(pcb);
|
565 |
|
|
return ERR_OK;
|
566 |
|
|
}
|
567 |
|
|
|
568 |
|
|
/* Update the PCB (in)activity timer. */
|
569 |
|
|
pcb->tmr = tcp_ticks;
|
570 |
|
|
pcb->keep_cnt_sent = 0;
|
571 |
|
|
|
572 |
|
|
tcp_parseopt(pcb);
|
573 |
|
|
|
574 |
|
|
/* Do different things depending on the TCP state. */
|
575 |
|
|
switch (pcb->state) {
|
576 |
|
|
case SYN_SENT:
|
577 |
|
|
LWIP_DEBUGF(TCP_INPUT_DEBUG, ("SYN-SENT: ackno %"U32_F" pcb->snd_nxt %"U32_F" unacked %"U32_F"\n", ackno,
|
578 |
|
|
pcb->snd_nxt, ntohl(pcb->unacked->tcphdr->seqno)));
|
579 |
|
|
/* received SYN ACK with expected sequence number? */
|
580 |
|
|
if ((flags & TCP_ACK) && (flags & TCP_SYN)
|
581 |
|
|
&& ackno == ntohl(pcb->unacked->tcphdr->seqno) + 1) {
|
582 |
|
|
pcb->snd_buf++;
|
583 |
|
|
pcb->rcv_nxt = seqno + 1;
|
584 |
|
|
pcb->rcv_ann_right_edge = pcb->rcv_nxt;
|
585 |
|
|
pcb->lastack = ackno;
|
586 |
|
|
pcb->snd_wnd = tcphdr->wnd;
|
587 |
|
|
pcb->snd_wl1 = seqno - 1; /* initialise to seqno - 1 to force window update */
|
588 |
|
|
pcb->state = ESTABLISHED;
|
589 |
|
|
|
590 |
|
|
#if TCP_CALCULATE_EFF_SEND_MSS
|
591 |
|
|
pcb->mss = tcp_eff_send_mss(pcb->mss, &(pcb->remote_ip));
|
592 |
|
|
#endif /* TCP_CALCULATE_EFF_SEND_MSS */
|
593 |
|
|
|
594 |
|
|
/* Set ssthresh again after changing pcb->mss (already set in tcp_connect
|
595 |
|
|
* but for the default value of pcb->mss) */
|
596 |
|
|
pcb->ssthresh = pcb->mss * 10;
|
597 |
|
|
|
598 |
|
|
pcb->cwnd = ((pcb->cwnd == 1) ? (pcb->mss * 2) : pcb->mss);
|
599 |
|
|
LWIP_ASSERT("pcb->snd_queuelen > 0", (pcb->snd_queuelen > 0));
|
600 |
|
|
--pcb->snd_queuelen;
|
601 |
|
|
LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_process: SYN-SENT --queuelen %"U16_F"\n", (u16_t)pcb->snd_queuelen));
|
602 |
|
|
rseg = pcb->unacked;
|
603 |
|
|
pcb->unacked = rseg->next;
|
604 |
|
|
|
605 |
|
|
/* If there's nothing left to acknowledge, stop the retransmit
|
606 |
|
|
timer, otherwise reset it to start again */
|
607 |
|
|
if(pcb->unacked == NULL)
|
608 |
|
|
pcb->rtime = -1;
|
609 |
|
|
else {
|
610 |
|
|
pcb->rtime = 0;
|
611 |
|
|
pcb->nrtx = 0;
|
612 |
|
|
}
|
613 |
|
|
|
614 |
|
|
tcp_seg_free(rseg);
|
615 |
|
|
|
616 |
|
|
/* Call the user specified function to call when sucessfully
|
617 |
|
|
* connected. */
|
618 |
|
|
TCP_EVENT_CONNECTED(pcb, ERR_OK, err);
|
619 |
|
|
tcp_ack_now(pcb);
|
620 |
|
|
}
|
621 |
|
|
/* received ACK? possibly a half-open connection */
|
622 |
|
|
else if (flags & TCP_ACK) {
|
623 |
|
|
/* send a RST to bring the other side in a non-synchronized state. */
|
624 |
|
|
tcp_rst(ackno, seqno + tcplen, &(iphdr->dest), &(iphdr->src),
|
625 |
|
|
tcphdr->dest, tcphdr->src);
|
626 |
|
|
}
|
627 |
|
|
break;
|
628 |
|
|
case SYN_RCVD:
|
629 |
|
|
if (flags & TCP_ACK) {
|
630 |
|
|
/* expected ACK number? */
|
631 |
|
|
if (TCP_SEQ_BETWEEN(ackno, pcb->lastack+1, pcb->snd_nxt)) {
|
632 |
|
|
u16_t old_cwnd;
|
633 |
|
|
pcb->state = ESTABLISHED;
|
634 |
|
|
LWIP_DEBUGF(TCP_DEBUG, ("TCP connection established %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
|
635 |
|
|
#if LWIP_CALLBACK_API
|
636 |
|
|
LWIP_ASSERT("pcb->accept != NULL", pcb->accept != NULL);
|
637 |
|
|
#endif
|
638 |
|
|
/* Call the accept function. */
|
639 |
|
|
TCP_EVENT_ACCEPT(pcb, ERR_OK, err);
|
640 |
|
|
if (err != ERR_OK) {
|
641 |
|
|
/* If the accept function returns with an error, we abort
|
642 |
|
|
* the connection. */
|
643 |
|
|
tcp_abort(pcb);
|
644 |
|
|
return ERR_ABRT;
|
645 |
|
|
}
|
646 |
|
|
old_cwnd = pcb->cwnd;
|
647 |
|
|
/* If there was any data contained within this ACK,
|
648 |
|
|
* we'd better pass it on to the application as well. */
|
649 |
|
|
tcp_receive(pcb);
|
650 |
|
|
|
651 |
|
|
/* Prevent ACK for SYN to generate a sent event */
|
652 |
|
|
if (pcb->acked != 0) {
|
653 |
|
|
pcb->acked--;
|
654 |
|
|
}
|
655 |
|
|
|
656 |
|
|
pcb->cwnd = ((old_cwnd == 1) ? (pcb->mss * 2) : pcb->mss);
|
657 |
|
|
|
658 |
|
|
if (recv_flags & TF_GOT_FIN) {
|
659 |
|
|
tcp_ack_now(pcb);
|
660 |
|
|
pcb->state = CLOSE_WAIT;
|
661 |
|
|
}
|
662 |
|
|
}
|
663 |
|
|
/* incorrect ACK number */
|
664 |
|
|
else {
|
665 |
|
|
/* send RST */
|
666 |
|
|
tcp_rst(ackno, seqno + tcplen, &(iphdr->dest), &(iphdr->src),
|
667 |
|
|
tcphdr->dest, tcphdr->src);
|
668 |
|
|
}
|
669 |
|
|
} else if ((flags & TCP_SYN) && (seqno == pcb->rcv_nxt - 1)) {
|
670 |
|
|
/* Looks like another copy of the SYN - retransmit our SYN-ACK */
|
671 |
|
|
tcp_rexmit(pcb);
|
672 |
|
|
}
|
673 |
|
|
break;
|
674 |
|
|
case CLOSE_WAIT:
|
675 |
|
|
/* FALLTHROUGH */
|
676 |
|
|
case ESTABLISHED:
|
677 |
|
|
tcp_receive(pcb);
|
678 |
|
|
if (recv_flags & TF_GOT_FIN) { /* passive close */
|
679 |
|
|
tcp_ack_now(pcb);
|
680 |
|
|
pcb->state = CLOSE_WAIT;
|
681 |
|
|
}
|
682 |
|
|
break;
|
683 |
|
|
case FIN_WAIT_1:
|
684 |
|
|
tcp_receive(pcb);
|
685 |
|
|
if (recv_flags & TF_GOT_FIN) {
|
686 |
|
|
if ((flags & TCP_ACK) && (ackno == pcb->snd_nxt)) {
|
687 |
|
|
LWIP_DEBUGF(TCP_DEBUG,
|
688 |
|
|
("TCP connection closed: FIN_WAIT_1 %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
|
689 |
|
|
tcp_ack_now(pcb);
|
690 |
|
|
tcp_pcb_purge(pcb);
|
691 |
|
|
TCP_RMV(&tcp_active_pcbs, pcb);
|
692 |
|
|
pcb->state = TIME_WAIT;
|
693 |
|
|
TCP_REG(&tcp_tw_pcbs, pcb);
|
694 |
|
|
} else {
|
695 |
|
|
tcp_ack_now(pcb);
|
696 |
|
|
pcb->state = CLOSING;
|
697 |
|
|
}
|
698 |
|
|
} else if ((flags & TCP_ACK) && (ackno == pcb->snd_nxt)) {
|
699 |
|
|
pcb->state = FIN_WAIT_2;
|
700 |
|
|
}
|
701 |
|
|
break;
|
702 |
|
|
case FIN_WAIT_2:
|
703 |
|
|
tcp_receive(pcb);
|
704 |
|
|
if (recv_flags & TF_GOT_FIN) {
|
705 |
|
|
LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: FIN_WAIT_2 %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
|
706 |
|
|
tcp_ack_now(pcb);
|
707 |
|
|
tcp_pcb_purge(pcb);
|
708 |
|
|
TCP_RMV(&tcp_active_pcbs, pcb);
|
709 |
|
|
pcb->state = TIME_WAIT;
|
710 |
|
|
TCP_REG(&tcp_tw_pcbs, pcb);
|
711 |
|
|
}
|
712 |
|
|
break;
|
713 |
|
|
case CLOSING:
|
714 |
|
|
tcp_receive(pcb);
|
715 |
|
|
if (flags & TCP_ACK && ackno == pcb->snd_nxt) {
|
716 |
|
|
LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: CLOSING %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
|
717 |
|
|
tcp_pcb_purge(pcb);
|
718 |
|
|
TCP_RMV(&tcp_active_pcbs, pcb);
|
719 |
|
|
pcb->state = TIME_WAIT;
|
720 |
|
|
TCP_REG(&tcp_tw_pcbs, pcb);
|
721 |
|
|
}
|
722 |
|
|
break;
|
723 |
|
|
case LAST_ACK:
|
724 |
|
|
tcp_receive(pcb);
|
725 |
|
|
if (flags & TCP_ACK && ackno == pcb->snd_nxt) {
|
726 |
|
|
LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: LAST_ACK %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
|
727 |
|
|
/* bugfix #21699: don't set pcb->state to CLOSED here or we risk leaking segments */
|
728 |
|
|
recv_flags |= TF_CLOSED;
|
729 |
|
|
}
|
730 |
|
|
break;
|
731 |
|
|
default:
|
732 |
|
|
break;
|
733 |
|
|
}
|
734 |
|
|
return ERR_OK;
|
735 |
|
|
}
|
736 |
|
|
|
737 |
|
|
#if TCP_QUEUE_OOSEQ
|
738 |
|
|
/**
|
739 |
|
|
* Insert segment into the list (segments covered with new one will be deleted)
|
740 |
|
|
*
|
741 |
|
|
* Called from tcp_receive()
|
742 |
|
|
*/
|
743 |
|
|
static void
|
744 |
|
|
tcp_oos_insert_segment(struct tcp_seg *cseg, struct tcp_seg *next)
|
745 |
|
|
{
|
746 |
|
|
struct tcp_seg *old_seg;
|
747 |
|
|
|
748 |
|
|
if (TCPH_FLAGS(cseg->tcphdr) & TCP_FIN) {
|
749 |
|
|
/* received segment overlaps all following segments */
|
750 |
|
|
tcp_segs_free(next);
|
751 |
|
|
next = NULL;
|
752 |
|
|
}
|
753 |
|
|
else {
|
754 |
|
|
/* delete some following segments
|
755 |
|
|
oos queue may have segments with FIN flag */
|
756 |
|
|
while (next &&
|
757 |
|
|
TCP_SEQ_GEQ((seqno + cseg->len),
|
758 |
|
|
(next->tcphdr->seqno + next->len))) {
|
759 |
|
|
/* cseg with FIN already processed */
|
760 |
|
|
if (TCPH_FLAGS(next->tcphdr) & TCP_FIN) {
|
761 |
|
|
TCPH_FLAGS_SET(cseg->tcphdr, TCPH_FLAGS(cseg->tcphdr) | TCP_FIN);
|
762 |
|
|
}
|
763 |
|
|
old_seg = next;
|
764 |
|
|
next = next->next;
|
765 |
|
|
tcp_seg_free(old_seg);
|
766 |
|
|
}
|
767 |
|
|
if (next &&
|
768 |
|
|
TCP_SEQ_GT(seqno + cseg->len, next->tcphdr->seqno)) {
|
769 |
|
|
/* We need to trim the incoming segment. */
|
770 |
|
|
cseg->len = (u16_t)(next->tcphdr->seqno - seqno);
|
771 |
|
|
pbuf_realloc(cseg->p, cseg->len);
|
772 |
|
|
}
|
773 |
|
|
}
|
774 |
|
|
cseg->next = next;
|
775 |
|
|
}
|
776 |
|
|
#endif
|
777 |
|
|
|
778 |
|
|
/**
|
779 |
|
|
* Called by tcp_process. Checks if the given segment is an ACK for outstanding
|
780 |
|
|
* data, and if so frees the memory of the buffered data. Next, is places the
|
781 |
|
|
* segment on any of the receive queues (pcb->recved or pcb->ooseq). If the segment
|
782 |
|
|
* is buffered, the pbuf is referenced by pbuf_ref so that it will not be freed until
|
783 |
|
|
* i it has been removed from the buffer.
|
784 |
|
|
*
|
785 |
|
|
* If the incoming segment constitutes an ACK for a segment that was used for RTT
|
786 |
|
|
* estimation, the RTT is estimated here as well.
|
787 |
|
|
*
|
788 |
|
|
* Called from tcp_process().
|
789 |
|
|
*/
|
790 |
|
|
static void
|
791 |
|
|
tcp_receive(struct tcp_pcb *pcb)
|
792 |
|
|
{
|
793 |
|
|
struct tcp_seg *next;
|
794 |
|
|
#if TCP_QUEUE_OOSEQ
|
795 |
|
|
struct tcp_seg *prev, *cseg;
|
796 |
|
|
#endif
|
797 |
|
|
struct pbuf *p;
|
798 |
|
|
s32_t off;
|
799 |
|
|
s16_t m;
|
800 |
|
|
u32_t right_wnd_edge;
|
801 |
|
|
u16_t new_tot_len;
|
802 |
|
|
int found_dupack = 0;
|
803 |
|
|
|
804 |
|
|
if (flags & TCP_ACK) {
|
805 |
|
|
right_wnd_edge = pcb->snd_wnd + pcb->snd_wl2;
|
806 |
|
|
|
807 |
|
|
/* Update window. */
|
808 |
|
|
if (TCP_SEQ_LT(pcb->snd_wl1, seqno) ||
|
809 |
|
|
(pcb->snd_wl1 == seqno && TCP_SEQ_LT(pcb->snd_wl2, ackno)) ||
|
810 |
|
|
(pcb->snd_wl2 == ackno && tcphdr->wnd > pcb->snd_wnd)) {
|
811 |
|
|
pcb->snd_wnd = tcphdr->wnd;
|
812 |
|
|
pcb->snd_wl1 = seqno;
|
813 |
|
|
pcb->snd_wl2 = ackno;
|
814 |
|
|
if (pcb->snd_wnd > 0 && pcb->persist_backoff > 0) {
|
815 |
|
|
pcb->persist_backoff = 0;
|
816 |
|
|
}
|
817 |
|
|
LWIP_DEBUGF(TCP_WND_DEBUG, ("tcp_receive: window update %"U16_F"\n", pcb->snd_wnd));
|
818 |
|
|
#if TCP_WND_DEBUG
|
819 |
|
|
} else {
|
820 |
|
|
if (pcb->snd_wnd != tcphdr->wnd) {
|
821 |
|
|
LWIP_DEBUGF(TCP_WND_DEBUG,
|
822 |
|
|
("tcp_receive: no window update lastack %"U32_F" ackno %"
|
823 |
|
|
U32_F" wl1 %"U32_F" seqno %"U32_F" wl2 %"U32_F"\n",
|
824 |
|
|
pcb->lastack, ackno, pcb->snd_wl1, seqno, pcb->snd_wl2));
|
825 |
|
|
}
|
826 |
|
|
#endif /* TCP_WND_DEBUG */
|
827 |
|
|
}
|
828 |
|
|
|
829 |
|
|
/* (From Stevens TCP/IP Illustrated Vol II, p970.) Its only a
|
830 |
|
|
* duplicate ack if:
|
831 |
|
|
* 1) It doesn't ACK new data
|
832 |
|
|
* 2) length of received packet is zero (i.e. no payload)
|
833 |
|
|
* 3) the advertised window hasn't changed
|
834 |
|
|
* 4) There is outstanding unacknowledged data (retransmission timer running)
|
835 |
|
|
* 5) The ACK is == biggest ACK sequence number so far seen (snd_una)
|
836 |
|
|
*
|
837 |
|
|
* If it passes all five, should process as a dupack:
|
838 |
|
|
* a) dupacks < 3: do nothing
|
839 |
|
|
* b) dupacks == 3: fast retransmit
|
840 |
|
|
* c) dupacks > 3: increase cwnd
|
841 |
|
|
*
|
842 |
|
|
* If it only passes 1-3, should reset dupack counter (and add to
|
843 |
|
|
* stats, which we don't do in lwIP)
|
844 |
|
|
*
|
845 |
|
|
* If it only passes 1, should reset dupack counter
|
846 |
|
|
*
|
847 |
|
|
*/
|
848 |
|
|
|
849 |
|
|
/* Clause 1 */
|
850 |
|
|
if (TCP_SEQ_LEQ(ackno, pcb->lastack)) {
|
851 |
|
|
pcb->acked = 0;
|
852 |
|
|
/* Clause 2 */
|
853 |
|
|
if (tcplen == 0) {
|
854 |
|
|
/* Clause 3 */
|
855 |
|
|
if (pcb->snd_wl2 + pcb->snd_wnd == right_wnd_edge){
|
856 |
|
|
/* Clause 4 */
|
857 |
|
|
if (pcb->rtime >= 0) {
|
858 |
|
|
/* Clause 5 */
|
859 |
|
|
if (pcb->lastack == ackno) {
|
860 |
|
|
found_dupack = 1;
|
861 |
|
|
if (pcb->dupacks + 1 > pcb->dupacks)
|
862 |
|
|
++pcb->dupacks;
|
863 |
|
|
if (pcb->dupacks > 3) {
|
864 |
|
|
/* Inflate the congestion window, but not if it means that
|
865 |
|
|
the value overflows. */
|
866 |
|
|
if ((u16_t)(pcb->cwnd + pcb->mss) > pcb->cwnd) {
|
867 |
|
|
pcb->cwnd += pcb->mss;
|
868 |
|
|
}
|
869 |
|
|
} else if (pcb->dupacks == 3) {
|
870 |
|
|
/* Do fast retransmit */
|
871 |
|
|
tcp_rexmit_fast(pcb);
|
872 |
|
|
}
|
873 |
|
|
}
|
874 |
|
|
}
|
875 |
|
|
}
|
876 |
|
|
}
|
877 |
|
|
/* If Clause (1) or more is true, but not a duplicate ack, reset
|
878 |
|
|
* count of consecutive duplicate acks */
|
879 |
|
|
if (!found_dupack) {
|
880 |
|
|
pcb->dupacks = 0;
|
881 |
|
|
}
|
882 |
|
|
} else if (TCP_SEQ_BETWEEN(ackno, pcb->lastack+1, pcb->snd_nxt)){
|
883 |
|
|
/* We come here when the ACK acknowledges new data. */
|
884 |
|
|
|
885 |
|
|
/* Reset the "IN Fast Retransmit" flag, since we are no longer
|
886 |
|
|
in fast retransmit. Also reset the congestion window to the
|
887 |
|
|
slow start threshold. */
|
888 |
|
|
if (pcb->flags & TF_INFR) {
|
889 |
|
|
pcb->flags &= ~TF_INFR;
|
890 |
|
|
pcb->cwnd = pcb->ssthresh;
|
891 |
|
|
}
|
892 |
|
|
|
893 |
|
|
/* Reset the number of retransmissions. */
|
894 |
|
|
pcb->nrtx = 0;
|
895 |
|
|
|
896 |
|
|
/* Reset the retransmission time-out. */
|
897 |
|
|
pcb->rto = (pcb->sa >> 3) + pcb->sv;
|
898 |
|
|
|
899 |
|
|
/* Update the send buffer space. Diff between the two can never exceed 64K? */
|
900 |
|
|
pcb->acked = (u16_t)(ackno - pcb->lastack);
|
901 |
|
|
|
902 |
|
|
pcb->snd_buf += pcb->acked;
|
903 |
|
|
|
904 |
|
|
/* Reset the fast retransmit variables. */
|
905 |
|
|
pcb->dupacks = 0;
|
906 |
|
|
pcb->lastack = ackno;
|
907 |
|
|
|
908 |
|
|
/* Update the congestion control variables (cwnd and
|
909 |
|
|
ssthresh). */
|
910 |
|
|
if (pcb->state >= ESTABLISHED) {
|
911 |
|
|
if (pcb->cwnd < pcb->ssthresh) {
|
912 |
|
|
if ((u16_t)(pcb->cwnd + pcb->mss) > pcb->cwnd) {
|
913 |
|
|
pcb->cwnd += pcb->mss;
|
914 |
|
|
}
|
915 |
|
|
LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_receive: slow start cwnd %"U16_F"\n", pcb->cwnd));
|
916 |
|
|
} else {
|
917 |
|
|
u16_t new_cwnd = (pcb->cwnd + pcb->mss * pcb->mss / pcb->cwnd);
|
918 |
|
|
if (new_cwnd > pcb->cwnd) {
|
919 |
|
|
pcb->cwnd = new_cwnd;
|
920 |
|
|
}
|
921 |
|
|
LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_receive: congestion avoidance cwnd %"U16_F"\n", pcb->cwnd));
|
922 |
|
|
}
|
923 |
|
|
}
|
924 |
|
|
LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: ACK for %"U32_F", unacked->seqno %"U32_F":%"U32_F"\n",
|
925 |
|
|
ackno,
|
926 |
|
|
pcb->unacked != NULL?
|
927 |
|
|
ntohl(pcb->unacked->tcphdr->seqno): 0,
|
928 |
|
|
pcb->unacked != NULL?
|
929 |
|
|
ntohl(pcb->unacked->tcphdr->seqno) + TCP_TCPLEN(pcb->unacked): 0));
|
930 |
|
|
|
931 |
|
|
/* Remove segment from the unacknowledged list if the incoming
|
932 |
|
|
ACK acknowlegdes them. */
|
933 |
|
|
while (pcb->unacked != NULL &&
|
934 |
|
|
TCP_SEQ_LEQ(ntohl(pcb->unacked->tcphdr->seqno) +
|
935 |
|
|
TCP_TCPLEN(pcb->unacked), ackno)) {
|
936 |
|
|
LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: removing %"U32_F":%"U32_F" from pcb->unacked\n",
|
937 |
|
|
ntohl(pcb->unacked->tcphdr->seqno),
|
938 |
|
|
ntohl(pcb->unacked->tcphdr->seqno) +
|
939 |
|
|
TCP_TCPLEN(pcb->unacked)));
|
940 |
|
|
|
941 |
|
|
next = pcb->unacked;
|
942 |
|
|
pcb->unacked = pcb->unacked->next;
|
943 |
|
|
|
944 |
|
|
LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_receive: queuelen %"U16_F" ... ", (u16_t)pcb->snd_queuelen));
|
945 |
|
|
LWIP_ASSERT("pcb->snd_queuelen >= pbuf_clen(next->p)", (pcb->snd_queuelen >= pbuf_clen(next->p)));
|
946 |
|
|
/* Prevent ACK for FIN to generate a sent event */
|
947 |
|
|
if ((pcb->acked != 0) && ((TCPH_FLAGS(next->tcphdr) & TCP_FIN) != 0)) {
|
948 |
|
|
pcb->acked--;
|
949 |
|
|
}
|
950 |
|
|
|
951 |
|
|
pcb->snd_queuelen -= pbuf_clen(next->p);
|
952 |
|
|
tcp_seg_free(next);
|
953 |
|
|
|
954 |
|
|
LWIP_DEBUGF(TCP_QLEN_DEBUG, ("%"U16_F" (after freeing unacked)\n", (u16_t)pcb->snd_queuelen));
|
955 |
|
|
if (pcb->snd_queuelen != 0) {
|
956 |
|
|
LWIP_ASSERT("tcp_receive: valid queue length", pcb->unacked != NULL ||
|
957 |
|
|
pcb->unsent != NULL);
|
958 |
|
|
}
|
959 |
|
|
}
|
960 |
|
|
|
961 |
|
|
/* If there's nothing left to acknowledge, stop the retransmit
|
962 |
|
|
timer, otherwise reset it to start again */
|
963 |
|
|
if(pcb->unacked == NULL)
|
964 |
|
|
pcb->rtime = -1;
|
965 |
|
|
else
|
966 |
|
|
pcb->rtime = 0;
|
967 |
|
|
|
968 |
|
|
pcb->polltmr = 0;
|
969 |
|
|
} else {
|
970 |
|
|
/* Fix bug bug #21582: out of sequence ACK, didn't really ack anything */
|
971 |
|
|
pcb->acked = 0;
|
972 |
|
|
}
|
973 |
|
|
|
974 |
|
|
/* We go through the ->unsent list to see if any of the segments
|
975 |
|
|
on the list are acknowledged by the ACK. This may seem
|
976 |
|
|
strange since an "unsent" segment shouldn't be acked. The
|
977 |
|
|
rationale is that lwIP puts all outstanding segments on the
|
978 |
|
|
->unsent list after a retransmission, so these segments may
|
979 |
|
|
in fact have been sent once. */
|
980 |
|
|
while (pcb->unsent != NULL &&
|
981 |
|
|
TCP_SEQ_BETWEEN(ackno, ntohl(pcb->unsent->tcphdr->seqno) +
|
982 |
|
|
TCP_TCPLEN(pcb->unsent), pcb->snd_nxt)) {
|
983 |
|
|
LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: removing %"U32_F":%"U32_F" from pcb->unsent\n",
|
984 |
|
|
ntohl(pcb->unsent->tcphdr->seqno), ntohl(pcb->unsent->tcphdr->seqno) +
|
985 |
|
|
TCP_TCPLEN(pcb->unsent)));
|
986 |
|
|
|
987 |
|
|
next = pcb->unsent;
|
988 |
|
|
pcb->unsent = pcb->unsent->next;
|
989 |
|
|
LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_receive: queuelen %"U16_F" ... ", (u16_t)pcb->snd_queuelen));
|
990 |
|
|
LWIP_ASSERT("pcb->snd_queuelen >= pbuf_clen(next->p)", (pcb->snd_queuelen >= pbuf_clen(next->p)));
|
991 |
|
|
/* Prevent ACK for FIN to generate a sent event */
|
992 |
|
|
if ((pcb->acked != 0) && ((TCPH_FLAGS(next->tcphdr) & TCP_FIN) != 0)) {
|
993 |
|
|
pcb->acked--;
|
994 |
|
|
}
|
995 |
|
|
pcb->snd_queuelen -= pbuf_clen(next->p);
|
996 |
|
|
tcp_seg_free(next);
|
997 |
|
|
LWIP_DEBUGF(TCP_QLEN_DEBUG, ("%"U16_F" (after freeing unsent)\n", (u16_t)pcb->snd_queuelen));
|
998 |
|
|
if (pcb->snd_queuelen != 0) {
|
999 |
|
|
LWIP_ASSERT("tcp_receive: valid queue length",
|
1000 |
|
|
pcb->unacked != NULL || pcb->unsent != NULL);
|
1001 |
|
|
}
|
1002 |
|
|
}
|
1003 |
|
|
/* End of ACK for new data processing. */
|
1004 |
|
|
|
1005 |
|
|
LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: pcb->rttest %"U32_F" rtseq %"U32_F" ackno %"U32_F"\n",
|
1006 |
|
|
pcb->rttest, pcb->rtseq, ackno));
|
1007 |
|
|
|
1008 |
|
|
/* RTT estimation calculations. This is done by checking if the
|
1009 |
|
|
incoming segment acknowledges the segment we use to take a
|
1010 |
|
|
round-trip time measurement. */
|
1011 |
|
|
if (pcb->rttest && TCP_SEQ_LT(pcb->rtseq, ackno)) {
|
1012 |
|
|
/* diff between this shouldn't exceed 32K since this are tcp timer ticks
|
1013 |
|
|
and a round-trip shouldn't be that long... */
|
1014 |
|
|
m = (s16_t)(tcp_ticks - pcb->rttest);
|
1015 |
|
|
|
1016 |
|
|
LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: experienced rtt %"U16_F" ticks (%"U16_F" msec).\n",
|
1017 |
|
|
m, m * TCP_SLOW_INTERVAL));
|
1018 |
|
|
|
1019 |
|
|
/* This is taken directly from VJs original code in his paper */
|
1020 |
|
|
m = m - (pcb->sa >> 3);
|
1021 |
|
|
pcb->sa += m;
|
1022 |
|
|
if (m < 0) {
|
1023 |
|
|
m = -m;
|
1024 |
|
|
}
|
1025 |
|
|
m = m - (pcb->sv >> 2);
|
1026 |
|
|
pcb->sv += m;
|
1027 |
|
|
pcb->rto = (pcb->sa >> 3) + pcb->sv;
|
1028 |
|
|
|
1029 |
|
|
LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: RTO %"U16_F" (%"U16_F" milliseconds)\n",
|
1030 |
|
|
pcb->rto, pcb->rto * TCP_SLOW_INTERVAL));
|
1031 |
|
|
|
1032 |
|
|
pcb->rttest = 0;
|
1033 |
|
|
}
|
1034 |
|
|
}
|
1035 |
|
|
|
1036 |
|
|
/* If the incoming segment contains data, we must process it
|
1037 |
|
|
further. */
|
1038 |
|
|
if (tcplen > 0) {
|
1039 |
|
|
/* This code basically does three things:
|
1040 |
|
|
|
1041 |
|
|
+) If the incoming segment contains data that is the next
|
1042 |
|
|
in-sequence data, this data is passed to the application. This
|
1043 |
|
|
might involve trimming the first edge of the data. The rcv_nxt
|
1044 |
|
|
variable and the advertised window are adjusted.
|
1045 |
|
|
|
1046 |
|
|
+) If the incoming segment has data that is above the next
|
1047 |
|
|
sequence number expected (->rcv_nxt), the segment is placed on
|
1048 |
|
|
the ->ooseq queue. This is done by finding the appropriate
|
1049 |
|
|
place in the ->ooseq queue (which is ordered by sequence
|
1050 |
|
|
number) and trim the segment in both ends if needed. An
|
1051 |
|
|
immediate ACK is sent to indicate that we received an
|
1052 |
|
|
out-of-sequence segment.
|
1053 |
|
|
|
1054 |
|
|
+) Finally, we check if the first segment on the ->ooseq queue
|
1055 |
|
|
now is in sequence (i.e., if rcv_nxt >= ooseq->seqno). If
|
1056 |
|
|
rcv_nxt > ooseq->seqno, we must trim the first edge of the
|
1057 |
|
|
segment on ->ooseq before we adjust rcv_nxt. The data in the
|
1058 |
|
|
segments that are now on sequence are chained onto the
|
1059 |
|
|
incoming segment so that we only need to call the application
|
1060 |
|
|
once.
|
1061 |
|
|
*/
|
1062 |
|
|
|
1063 |
|
|
/* First, we check if we must trim the first edge. We have to do
|
1064 |
|
|
this if the sequence number of the incoming segment is less
|
1065 |
|
|
than rcv_nxt, and the sequence number plus the length of the
|
1066 |
|
|
segment is larger than rcv_nxt. */
|
1067 |
|
|
/* if (TCP_SEQ_LT(seqno, pcb->rcv_nxt)){
|
1068 |
|
|
if (TCP_SEQ_LT(pcb->rcv_nxt, seqno + tcplen)) {*/
|
1069 |
|
|
if (TCP_SEQ_BETWEEN(pcb->rcv_nxt, seqno + 1, seqno + tcplen - 1)){
|
1070 |
|
|
/* Trimming the first edge is done by pushing the payload
|
1071 |
|
|
pointer in the pbuf downwards. This is somewhat tricky since
|
1072 |
|
|
we do not want to discard the full contents of the pbuf up to
|
1073 |
|
|
the new starting point of the data since we have to keep the
|
1074 |
|
|
TCP header which is present in the first pbuf in the chain.
|
1075 |
|
|
|
1076 |
|
|
What is done is really quite a nasty hack: the first pbuf in
|
1077 |
|
|
the pbuf chain is pointed to by inseg.p. Since we need to be
|
1078 |
|
|
able to deallocate the whole pbuf, we cannot change this
|
1079 |
|
|
inseg.p pointer to point to any of the later pbufs in the
|
1080 |
|
|
chain. Instead, we point the ->payload pointer in the first
|
1081 |
|
|
pbuf to data in one of the later pbufs. We also set the
|
1082 |
|
|
inseg.data pointer to point to the right place. This way, the
|
1083 |
|
|
->p pointer will still point to the first pbuf, but the
|
1084 |
|
|
->p->payload pointer will point to data in another pbuf.
|
1085 |
|
|
|
1086 |
|
|
After we are done with adjusting the pbuf pointers we must
|
1087 |
|
|
adjust the ->data pointer in the seg and the segment
|
1088 |
|
|
length.*/
|
1089 |
|
|
|
1090 |
|
|
off = pcb->rcv_nxt - seqno;
|
1091 |
|
|
p = inseg.p;
|
1092 |
|
|
LWIP_ASSERT("inseg.p != NULL", inseg.p);
|
1093 |
|
|
LWIP_ASSERT("insane offset!", (off < 0x7fff));
|
1094 |
|
|
if (inseg.p->len < off) {
|
1095 |
|
|
LWIP_ASSERT("pbuf too short!", (((s32_t)inseg.p->tot_len) >= off));
|
1096 |
|
|
new_tot_len = (u16_t)(inseg.p->tot_len - off);
|
1097 |
|
|
while (p->len < off) {
|
1098 |
|
|
off -= p->len;
|
1099 |
|
|
/* KJM following line changed (with addition of new_tot_len var)
|
1100 |
|
|
to fix bug #9076
|
1101 |
|
|
inseg.p->tot_len -= p->len; */
|
1102 |
|
|
p->tot_len = new_tot_len;
|
1103 |
|
|
p->len = 0;
|
1104 |
|
|
p = p->next;
|
1105 |
|
|
}
|
1106 |
|
|
if(pbuf_header(p, (s16_t)-off)) {
|
1107 |
|
|
/* Do we need to cope with this failing? Assert for now */
|
1108 |
|
|
LWIP_ASSERT("pbuf_header failed", 0);
|
1109 |
|
|
}
|
1110 |
|
|
} else {
|
1111 |
|
|
if(pbuf_header(inseg.p, (s16_t)-off)) {
|
1112 |
|
|
/* Do we need to cope with this failing? Assert for now */
|
1113 |
|
|
LWIP_ASSERT("pbuf_header failed", 0);
|
1114 |
|
|
}
|
1115 |
|
|
}
|
1116 |
|
|
/* KJM following line changed to use p->payload rather than inseg->p->payload
|
1117 |
|
|
to fix bug #9076 */
|
1118 |
|
|
inseg.dataptr = p->payload;
|
1119 |
|
|
inseg.len -= (u16_t)(pcb->rcv_nxt - seqno);
|
1120 |
|
|
inseg.tcphdr->seqno = seqno = pcb->rcv_nxt;
|
1121 |
|
|
}
|
1122 |
|
|
else {
|
1123 |
|
|
if (TCP_SEQ_LT(seqno, pcb->rcv_nxt)){
|
1124 |
|
|
/* the whole segment is < rcv_nxt */
|
1125 |
|
|
/* must be a duplicate of a packet that has already been correctly handled */
|
1126 |
|
|
|
1127 |
|
|
LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: duplicate seqno %"U32_F"\n", seqno));
|
1128 |
|
|
tcp_ack_now(pcb);
|
1129 |
|
|
}
|
1130 |
|
|
}
|
1131 |
|
|
|
1132 |
|
|
/* The sequence number must be within the window (above rcv_nxt
|
1133 |
|
|
and below rcv_nxt + rcv_wnd) in order to be further
|
1134 |
|
|
processed. */
|
1135 |
|
|
if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt,
|
1136 |
|
|
pcb->rcv_nxt + pcb->rcv_wnd - 1)){
|
1137 |
|
|
if (pcb->rcv_nxt == seqno) {
|
1138 |
|
|
/* The incoming segment is the next in sequence. We check if
|
1139 |
|
|
we have to trim the end of the segment and update rcv_nxt
|
1140 |
|
|
and pass the data to the application. */
|
1141 |
|
|
tcplen = TCP_TCPLEN(&inseg);
|
1142 |
|
|
|
1143 |
|
|
if (tcplen > pcb->rcv_wnd) {
|
1144 |
|
|
LWIP_DEBUGF(TCP_INPUT_DEBUG,
|
1145 |
|
|
("tcp_receive: other end overran receive window"
|
1146 |
|
|
"seqno %"U32_F" len %"U32_F" right edge %"U32_F"\n",
|
1147 |
|
|
seqno, tcplen, pcb->rcv_nxt + pcb->rcv_wnd));
|
1148 |
|
|
if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
|
1149 |
|
|
/* Must remove the FIN from the header as we're trimming
|
1150 |
|
|
* that byte of sequence-space from the packet */
|
1151 |
|
|
TCPH_FLAGS_SET(inseg.tcphdr, TCPH_FLAGS(inseg.tcphdr) &~ TCP_FIN);
|
1152 |
|
|
}
|
1153 |
|
|
/* Adjust length of segment to fit in the window. */
|
1154 |
|
|
inseg.len = pcb->rcv_wnd;
|
1155 |
|
|
if (TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) {
|
1156 |
|
|
inseg.len -= 1;
|
1157 |
|
|
}
|
1158 |
|
|
pbuf_realloc(inseg.p, inseg.len);
|
1159 |
|
|
tcplen = TCP_TCPLEN(&inseg);
|
1160 |
|
|
LWIP_ASSERT("tcp_receive: segment not trimmed correctly to rcv_wnd\n",
|
1161 |
|
|
(seqno + tcplen) == (pcb->rcv_nxt + pcb->rcv_wnd));
|
1162 |
|
|
}
|
1163 |
|
|
#if TCP_QUEUE_OOSEQ
|
1164 |
|
|
if (pcb->ooseq != NULL) {
|
1165 |
|
|
if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
|
1166 |
|
|
LWIP_DEBUGF(TCP_INPUT_DEBUG,
|
1167 |
|
|
("tcp_receive: received in-order FIN, binning ooseq queue\n"));
|
1168 |
|
|
/* Received in-order FIN means anything that was received
|
1169 |
|
|
* out of order must now have been received in-order, so
|
1170 |
|
|
* bin the ooseq queue
|
1171 |
|
|
* rcv_nxt
|
1172 |
|
|
* . |--ooseq--|
|
1173 |
|
|
* .==seg============|FIN
|
1174 |
|
|
*/
|
1175 |
|
|
while (pcb->ooseq != NULL) {
|
1176 |
|
|
struct tcp_seg *old_ooseq = pcb->ooseq;
|
1177 |
|
|
pcb->ooseq = pcb->ooseq->next;
|
1178 |
|
|
tcp_seg_free(old_ooseq);
|
1179 |
|
|
}
|
1180 |
|
|
}
|
1181 |
|
|
else {
|
1182 |
|
|
struct tcp_seg* next = pcb->ooseq;
|
1183 |
|
|
struct tcp_seg *old_seg;
|
1184 |
|
|
/* rcv_nxt
|
1185 |
|
|
* . |--ooseq--|
|
1186 |
|
|
* .==seg============|
|
1187 |
|
|
*/
|
1188 |
|
|
while (next &&
|
1189 |
|
|
TCP_SEQ_GEQ(seqno + tcplen,
|
1190 |
|
|
next->tcphdr->seqno + next->len)) {
|
1191 |
|
|
/* inseg doesn't have FIN (already processed) */
|
1192 |
|
|
if (TCPH_FLAGS(next->tcphdr) & TCP_FIN &&
|
1193 |
|
|
(TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) == 0) {
|
1194 |
|
|
TCPH_FLAGS_SET(inseg.tcphdr,
|
1195 |
|
|
TCPH_FLAGS(inseg.tcphdr) | TCP_FIN);
|
1196 |
|
|
tcplen = TCP_TCPLEN(&inseg);
|
1197 |
|
|
}
|
1198 |
|
|
old_seg = next;
|
1199 |
|
|
next = next->next;
|
1200 |
|
|
tcp_seg_free(old_seg);
|
1201 |
|
|
}
|
1202 |
|
|
/* rcv_nxt
|
1203 |
|
|
* . |--ooseq--|
|
1204 |
|
|
* .==seg============|
|
1205 |
|
|
*/
|
1206 |
|
|
if (next &&
|
1207 |
|
|
TCP_SEQ_GT(seqno + tcplen,
|
1208 |
|
|
next->tcphdr->seqno)) {
|
1209 |
|
|
/* FIN in inseg already handled by dropping whole ooseq queue */
|
1210 |
|
|
inseg.len = (u16_t)(pcb->ooseq->tcphdr->seqno - seqno);
|
1211 |
|
|
if (TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) {
|
1212 |
|
|
inseg.len -= 1;
|
1213 |
|
|
}
|
1214 |
|
|
pbuf_realloc(inseg.p, inseg.len);
|
1215 |
|
|
tcplen = TCP_TCPLEN(&inseg);
|
1216 |
|
|
LWIP_ASSERT("tcp_receive: segment not trimmed correctly to ooseq queue\n",
|
1217 |
|
|
(seqno + tcplen) == pcb->ooseq->tcphdr->seqno);
|
1218 |
|
|
}
|
1219 |
|
|
pcb->ooseq = next;
|
1220 |
|
|
}
|
1221 |
|
|
}
|
1222 |
|
|
#endif /* TCP_QUEUE_OOSEQ */
|
1223 |
|
|
|
1224 |
|
|
pcb->rcv_nxt = seqno + tcplen;
|
1225 |
|
|
|
1226 |
|
|
/* Update the receiver's (our) window. */
|
1227 |
|
|
LWIP_ASSERT("tcp_receive: tcplen > rcv_wnd\n", pcb->rcv_wnd >= tcplen);
|
1228 |
|
|
pcb->rcv_wnd -= tcplen;
|
1229 |
|
|
|
1230 |
|
|
tcp_update_rcv_ann_wnd(pcb);
|
1231 |
|
|
|
1232 |
|
|
/* If there is data in the segment, we make preparations to
|
1233 |
|
|
pass this up to the application. The ->recv_data variable
|
1234 |
|
|
is used for holding the pbuf that goes to the
|
1235 |
|
|
application. The code for reassembling out-of-sequence data
|
1236 |
|
|
chains its data on this pbuf as well.
|
1237 |
|
|
|
1238 |
|
|
If the segment was a FIN, we set the TF_GOT_FIN flag that will
|
1239 |
|
|
be used to indicate to the application that the remote side has
|
1240 |
|
|
closed its end of the connection. */
|
1241 |
|
|
if (inseg.p->tot_len > 0) {
|
1242 |
|
|
recv_data = inseg.p;
|
1243 |
|
|
/* Since this pbuf now is the responsibility of the
|
1244 |
|
|
application, we delete our reference to it so that we won't
|
1245 |
|
|
(mistakingly) deallocate it. */
|
1246 |
|
|
inseg.p = NULL;
|
1247 |
|
|
}
|
1248 |
|
|
if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
|
1249 |
|
|
LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: received FIN.\n"));
|
1250 |
|
|
recv_flags |= TF_GOT_FIN;
|
1251 |
|
|
}
|
1252 |
|
|
|
1253 |
|
|
#if TCP_QUEUE_OOSEQ
|
1254 |
|
|
/* We now check if we have segments on the ->ooseq queue that
|
1255 |
|
|
is now in sequence. */
|
1256 |
|
|
while (pcb->ooseq != NULL &&
|
1257 |
|
|
pcb->ooseq->tcphdr->seqno == pcb->rcv_nxt) {
|
1258 |
|
|
|
1259 |
|
|
cseg = pcb->ooseq;
|
1260 |
|
|
seqno = pcb->ooseq->tcphdr->seqno;
|
1261 |
|
|
|
1262 |
|
|
pcb->rcv_nxt += TCP_TCPLEN(cseg);
|
1263 |
|
|
LWIP_ASSERT("tcp_receive: ooseq tcplen > rcv_wnd\n",
|
1264 |
|
|
pcb->rcv_wnd >= TCP_TCPLEN(cseg));
|
1265 |
|
|
pcb->rcv_wnd -= TCP_TCPLEN(cseg);
|
1266 |
|
|
|
1267 |
|
|
tcp_update_rcv_ann_wnd(pcb);
|
1268 |
|
|
|
1269 |
|
|
if (cseg->p->tot_len > 0) {
|
1270 |
|
|
/* Chain this pbuf onto the pbuf that we will pass to
|
1271 |
|
|
the application. */
|
1272 |
|
|
if (recv_data) {
|
1273 |
|
|
pbuf_cat(recv_data, cseg->p);
|
1274 |
|
|
} else {
|
1275 |
|
|
recv_data = cseg->p;
|
1276 |
|
|
}
|
1277 |
|
|
cseg->p = NULL;
|
1278 |
|
|
}
|
1279 |
|
|
if (TCPH_FLAGS(cseg->tcphdr) & TCP_FIN) {
|
1280 |
|
|
LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: dequeued FIN.\n"));
|
1281 |
|
|
recv_flags |= TF_GOT_FIN;
|
1282 |
|
|
if (pcb->state == ESTABLISHED) { /* force passive close or we can move to active close */
|
1283 |
|
|
pcb->state = CLOSE_WAIT;
|
1284 |
|
|
}
|
1285 |
|
|
}
|
1286 |
|
|
|
1287 |
|
|
pcb->ooseq = cseg->next;
|
1288 |
|
|
tcp_seg_free(cseg);
|
1289 |
|
|
}
|
1290 |
|
|
#endif /* TCP_QUEUE_OOSEQ */
|
1291 |
|
|
|
1292 |
|
|
|
1293 |
|
|
/* Acknowledge the segment(s). */
|
1294 |
|
|
tcp_ack(pcb);
|
1295 |
|
|
|
1296 |
|
|
} else {
|
1297 |
|
|
/* We get here if the incoming segment is out-of-sequence. */
|
1298 |
|
|
tcp_send_empty_ack(pcb);
|
1299 |
|
|
#if TCP_QUEUE_OOSEQ
|
1300 |
|
|
/* We queue the segment on the ->ooseq queue. */
|
1301 |
|
|
if (pcb->ooseq == NULL) {
|
1302 |
|
|
pcb->ooseq = tcp_seg_copy(&inseg);
|
1303 |
|
|
} else {
|
1304 |
|
|
/* If the queue is not empty, we walk through the queue and
|
1305 |
|
|
try to find a place where the sequence number of the
|
1306 |
|
|
incoming segment is between the sequence numbers of the
|
1307 |
|
|
previous and the next segment on the ->ooseq queue. That is
|
1308 |
|
|
the place where we put the incoming segment. If needed, we
|
1309 |
|
|
trim the second edges of the previous and the incoming
|
1310 |
|
|
segment so that it will fit into the sequence.
|
1311 |
|
|
|
1312 |
|
|
If the incoming segment has the same sequence number as a
|
1313 |
|
|
segment on the ->ooseq queue, we discard the segment that
|
1314 |
|
|
contains less data. */
|
1315 |
|
|
|
1316 |
|
|
prev = NULL;
|
1317 |
|
|
for(next = pcb->ooseq; next != NULL; next = next->next) {
|
1318 |
|
|
if (seqno == next->tcphdr->seqno) {
|
1319 |
|
|
/* The sequence number of the incoming segment is the
|
1320 |
|
|
same as the sequence number of the segment on
|
1321 |
|
|
->ooseq. We check the lengths to see which one to
|
1322 |
|
|
discard. */
|
1323 |
|
|
if (inseg.len > next->len) {
|
1324 |
|
|
/* The incoming segment is larger than the old
|
1325 |
|
|
segment. We replace some segments with the new
|
1326 |
|
|
one. */
|
1327 |
|
|
cseg = tcp_seg_copy(&inseg);
|
1328 |
|
|
if (cseg != NULL) {
|
1329 |
|
|
if (prev != NULL) {
|
1330 |
|
|
prev->next = cseg;
|
1331 |
|
|
} else {
|
1332 |
|
|
pcb->ooseq = cseg;
|
1333 |
|
|
}
|
1334 |
|
|
tcp_oos_insert_segment(cseg, next);
|
1335 |
|
|
}
|
1336 |
|
|
break;
|
1337 |
|
|
} else {
|
1338 |
|
|
/* Either the lenghts are the same or the incoming
|
1339 |
|
|
segment was smaller than the old one; in either
|
1340 |
|
|
case, we ditch the incoming segment. */
|
1341 |
|
|
break;
|
1342 |
|
|
}
|
1343 |
|
|
} else {
|
1344 |
|
|
if (prev == NULL) {
|
1345 |
|
|
if (TCP_SEQ_LT(seqno, next->tcphdr->seqno)) {
|
1346 |
|
|
/* The sequence number of the incoming segment is lower
|
1347 |
|
|
than the sequence number of the first segment on the
|
1348 |
|
|
queue. We put the incoming segment first on the
|
1349 |
|
|
queue. */
|
1350 |
|
|
cseg = tcp_seg_copy(&inseg);
|
1351 |
|
|
if (cseg != NULL) {
|
1352 |
|
|
pcb->ooseq = cseg;
|
1353 |
|
|
tcp_oos_insert_segment(cseg, next);
|
1354 |
|
|
}
|
1355 |
|
|
break;
|
1356 |
|
|
}
|
1357 |
|
|
} else {
|
1358 |
|
|
/*if (TCP_SEQ_LT(prev->tcphdr->seqno, seqno) &&
|
1359 |
|
|
TCP_SEQ_LT(seqno, next->tcphdr->seqno)) {*/
|
1360 |
|
|
if (TCP_SEQ_BETWEEN(seqno, prev->tcphdr->seqno+1, next->tcphdr->seqno-1)) {
|
1361 |
|
|
/* The sequence number of the incoming segment is in
|
1362 |
|
|
between the sequence numbers of the previous and
|
1363 |
|
|
the next segment on ->ooseq. We trim trim the previous
|
1364 |
|
|
segment, delete next segments that included in received segment
|
1365 |
|
|
and trim received, if needed. */
|
1366 |
|
|
cseg = tcp_seg_copy(&inseg);
|
1367 |
|
|
if (cseg != NULL) {
|
1368 |
|
|
if (TCP_SEQ_GT(prev->tcphdr->seqno + prev->len, seqno)) {
|
1369 |
|
|
/* We need to trim the prev segment. */
|
1370 |
|
|
prev->len = (u16_t)(seqno - prev->tcphdr->seqno);
|
1371 |
|
|
pbuf_realloc(prev->p, prev->len);
|
1372 |
|
|
}
|
1373 |
|
|
prev->next = cseg;
|
1374 |
|
|
tcp_oos_insert_segment(cseg, next);
|
1375 |
|
|
}
|
1376 |
|
|
break;
|
1377 |
|
|
}
|
1378 |
|
|
}
|
1379 |
|
|
/* If the "next" segment is the last segment on the
|
1380 |
|
|
ooseq queue, we add the incoming segment to the end
|
1381 |
|
|
of the list. */
|
1382 |
|
|
if (next->next == NULL &&
|
1383 |
|
|
TCP_SEQ_GT(seqno, next->tcphdr->seqno)) {
|
1384 |
|
|
if (TCPH_FLAGS(next->tcphdr) & TCP_FIN) {
|
1385 |
|
|
/* segment "next" already contains all data */
|
1386 |
|
|
break;
|
1387 |
|
|
}
|
1388 |
|
|
next->next = tcp_seg_copy(&inseg);
|
1389 |
|
|
if (next->next != NULL) {
|
1390 |
|
|
if (TCP_SEQ_GT(next->tcphdr->seqno + next->len, seqno)) {
|
1391 |
|
|
/* We need to trim the last segment. */
|
1392 |
|
|
next->len = (u16_t)(seqno - next->tcphdr->seqno);
|
1393 |
|
|
pbuf_realloc(next->p, next->len);
|
1394 |
|
|
}
|
1395 |
|
|
}
|
1396 |
|
|
break;
|
1397 |
|
|
}
|
1398 |
|
|
}
|
1399 |
|
|
prev = next;
|
1400 |
|
|
}
|
1401 |
|
|
}
|
1402 |
|
|
#endif /* TCP_QUEUE_OOSEQ */
|
1403 |
|
|
|
1404 |
|
|
}
|
1405 |
|
|
} else {
|
1406 |
|
|
/* The incoming segment is not withing the window. */
|
1407 |
|
|
tcp_send_empty_ack(pcb);
|
1408 |
|
|
}
|
1409 |
|
|
} else {
|
1410 |
|
|
/* Segments with length 0 is taken care of here. Segments that
|
1411 |
|
|
fall out of the window are ACKed. */
|
1412 |
|
|
/*if (TCP_SEQ_GT(pcb->rcv_nxt, seqno) ||
|
1413 |
|
|
TCP_SEQ_GEQ(seqno, pcb->rcv_nxt + pcb->rcv_wnd)) {*/
|
1414 |
|
|
if(!TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt, pcb->rcv_nxt + pcb->rcv_wnd-1)){
|
1415 |
|
|
tcp_ack_now(pcb);
|
1416 |
|
|
}
|
1417 |
|
|
}
|
1418 |
|
|
}
|
1419 |
|
|
|
1420 |
|
|
/**
|
1421 |
|
|
* Parses the options contained in the incoming segment.
|
1422 |
|
|
*
|
1423 |
|
|
* Called from tcp_listen_input() and tcp_process().
|
1424 |
|
|
* Currently, only the MSS option is supported!
|
1425 |
|
|
*
|
1426 |
|
|
* @param pcb the tcp_pcb for which a segment arrived
|
1427 |
|
|
*/
|
1428 |
|
|
static void
|
1429 |
|
|
tcp_parseopt(struct tcp_pcb *pcb)
|
1430 |
|
|
{
|
1431 |
|
|
u16_t c, max_c;
|
1432 |
|
|
u16_t mss;
|
1433 |
|
|
u8_t *opts, opt;
|
1434 |
|
|
#if LWIP_TCP_TIMESTAMPS
|
1435 |
|
|
u32_t tsval;
|
1436 |
|
|
#endif
|
1437 |
|
|
|
1438 |
|
|
opts = (u8_t *)tcphdr + TCP_HLEN;
|
1439 |
|
|
|
1440 |
|
|
/* Parse the TCP MSS option, if present. */
|
1441 |
|
|
if(TCPH_HDRLEN(tcphdr) > 0x5) {
|
1442 |
|
|
max_c = (TCPH_HDRLEN(tcphdr) - 5) << 2;
|
1443 |
|
|
for (c = 0; c < max_c; ) {
|
1444 |
|
|
opt = opts[c];
|
1445 |
|
|
switch (opt) {
|
1446 |
|
|
case 0x00:
|
1447 |
|
|
/* End of options. */
|
1448 |
|
|
LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: EOL\n"));
|
1449 |
|
|
return;
|
1450 |
|
|
case 0x01:
|
1451 |
|
|
/* NOP option. */
|
1452 |
|
|
++c;
|
1453 |
|
|
LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: NOP\n"));
|
1454 |
|
|
break;
|
1455 |
|
|
case 0x02:
|
1456 |
|
|
LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: MSS\n"));
|
1457 |
|
|
if (opts[c + 1] != 0x04 || c + 0x04 > max_c) {
|
1458 |
|
|
/* Bad length */
|
1459 |
|
|
LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
|
1460 |
|
|
return;
|
1461 |
|
|
}
|
1462 |
|
|
/* An MSS option with the right option length. */
|
1463 |
|
|
mss = (opts[c + 2] << 8) | opts[c + 3];
|
1464 |
|
|
/* Limit the mss to the configured TCP_MSS and prevent division by zero */
|
1465 |
|
|
pcb->mss = ((mss > TCP_MSS) || (mss == 0)) ? TCP_MSS : mss;
|
1466 |
|
|
/* Advance to next option */
|
1467 |
|
|
c += 0x04;
|
1468 |
|
|
break;
|
1469 |
|
|
#if LWIP_TCP_TIMESTAMPS
|
1470 |
|
|
case 0x08:
|
1471 |
|
|
LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: TS\n"));
|
1472 |
|
|
if (opts[c + 1] != 0x0A || c + 0x0A > max_c) {
|
1473 |
|
|
/* Bad length */
|
1474 |
|
|
LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
|
1475 |
|
|
return;
|
1476 |
|
|
}
|
1477 |
|
|
/* TCP timestamp option with valid length */
|
1478 |
|
|
tsval = (opts[c+2]) | (opts[c+3] << 8) |
|
1479 |
|
|
(opts[c+4] << 16) | (opts[c+5] << 24);
|
1480 |
|
|
if (flags & TCP_SYN) {
|
1481 |
|
|
pcb->ts_recent = ntohl(tsval);
|
1482 |
|
|
pcb->flags |= TF_TIMESTAMP;
|
1483 |
|
|
} else if (TCP_SEQ_BETWEEN(pcb->ts_lastacksent, seqno, seqno+tcplen)) {
|
1484 |
|
|
pcb->ts_recent = ntohl(tsval);
|
1485 |
|
|
}
|
1486 |
|
|
/* Advance to next option */
|
1487 |
|
|
c += 0x0A;
|
1488 |
|
|
break;
|
1489 |
|
|
#endif
|
1490 |
|
|
default:
|
1491 |
|
|
LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: other\n"));
|
1492 |
|
|
if (opts[c + 1] == 0) {
|
1493 |
|
|
LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
|
1494 |
|
|
/* If the length field is zero, the options are malformed
|
1495 |
|
|
and we don't process them further. */
|
1496 |
|
|
return;
|
1497 |
|
|
}
|
1498 |
|
|
/* All other options have a length field, so that we easily
|
1499 |
|
|
can skip past them. */
|
1500 |
|
|
c += opts[c + 1];
|
1501 |
|
|
}
|
1502 |
|
|
}
|
1503 |
|
|
}
|
1504 |
|
|
}
|
1505 |
|
|
|
1506 |
|
|
#endif /* LWIP_TCP */
|