Hendrik Lipka
Stripped down version of Segundos NetService library (http://mbed.org/users/segundo/libraries/NetServices ). I have removed all NetServices, and all functions which had been disabled. Use this version when you need only pure TCP or UDP functions - this library compiles faster.
Dependents: christmasLights device_server pop3demo device_server_udp ... more
Diff: lwip/core/tcp_in.c
- Revision:
- 1:9d93f4dc2f46
- Parent:
- 0:8b387bed54c2
--- a/lwip/core/tcp_in.c Mon Jan 10 21:03:11 2011 +0000
+++ /dev/null Thu Jan 01 00:00:00 1970 +0000
@@ -1,1569 +0,0 @@
-/**
- * @file
- * Transmission Control Protocol, incoming traffic
- *
- * The input processing functions of the TCP layer.
- *
- * These functions are generally called in the order (ip_input() ->)
- * tcp_input() -> * tcp_process() -> tcp_receive() (-> application).
- *
- */
-
-/*
- * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without modification,
- * are permitted provided that the following conditions are met:
- *
- * 1. Redistributions of source code must retain the above copyright notice,
- * this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright notice,
- * this list of conditions and the following disclaimer in the documentation
- * and/or other materials provided with the distribution.
- * 3. The name of the author may not be used to endorse or promote products
- * derived from this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
- * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
- * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
- * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
- * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
- * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
- * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
- * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
- * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
- * OF SUCH DAMAGE.
- *
- * This file is part of the lwIP TCP/IP stack.
- *
- * Author: Adam Dunkels <adam@sics.se>
- *
- */
-
-#include "lwip/opt.h"
-
-#if LWIP_TCP /* don't build if not configured for use in lwipopts.h */
-
-#include "lwip/tcp_impl.h"
-#include "lwip/def.h"
-#include "lwip/ip_addr.h"
-#include "lwip/netif.h"
-#include "lwip/mem.h"
-#include "lwip/memp.h"
-#include "lwip/inet_chksum.h"
-#include "lwip/stats.h"
-#include "lwip/snmp.h"
-#include "arch/perf.h"
-
-/* These variables are global to all functions involved in the input
- processing of TCP segments. They are set by the tcp_input()
- function. */
-static struct tcp_seg inseg;
-static struct tcp_hdr *tcphdr;
-static struct ip_hdr *iphdr;
-static u32_t seqno, ackno;
-static u8_t flags;
-static u16_t tcplen;
-
-static u8_t recv_flags;
-static struct pbuf *recv_data;
-
-struct tcp_pcb *tcp_input_pcb;
-
-/* Forward declarations. */
-static err_t tcp_process(struct tcp_pcb *pcb);
-static void tcp_receive(struct tcp_pcb *pcb);
-static void tcp_parseopt(struct tcp_pcb *pcb);
-
-static err_t tcp_listen_input(struct tcp_pcb_listen *pcb);
-static err_t tcp_timewait_input(struct tcp_pcb *pcb);
-
-/**
- * The initial input processing of TCP. It verifies the TCP header, demultiplexes
- * the segment between the PCBs and passes it on to tcp_process(), which implements
- * the TCP finite state machine. This function is called by the IP layer (in
- * ip_input()).
- *
- * @param p received TCP segment to process (p->payload pointing to the IP header)
- * @param inp network interface on which this segment was received
- */
-void
-tcp_input(struct pbuf *p, struct netif *inp)
-{
- struct tcp_pcb *pcb, *prev;
- struct tcp_pcb_listen *lpcb;
-#if SO_REUSE
- struct tcp_pcb *lpcb_prev = NULL;
- struct tcp_pcb_listen *lpcb_any = NULL;
-#endif /* SO_REUSE */
- u8_t hdrlen;
- err_t err;
-
- PERF_START;
-
- TCP_STATS_INC(tcp.recv);
- snmp_inc_tcpinsegs();
-
- iphdr = (struct ip_hdr *)p->payload;
- tcphdr = (struct tcp_hdr *)((u8_t *)p->payload + IPH_HL(iphdr) * 4);
-
-#if TCP_INPUT_DEBUG
- tcp_debug_print(tcphdr);
-#endif
-
- /* remove header from payload */
- if (pbuf_header(p, -((s16_t)(IPH_HL(iphdr) * 4))) || (p->tot_len < sizeof(struct tcp_hdr))) {
- /* drop short packets */
- LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: short packet (%"U16_F" bytes) discarded\n", p->tot_len));
- TCP_STATS_INC(tcp.lenerr);
- TCP_STATS_INC(tcp.drop);
- snmp_inc_tcpinerrs();
- pbuf_free(p);
- return;
- }
-
- /* Don't even process incoming broadcasts/multicasts. */
- if (ip_addr_isbroadcast(¤t_iphdr_dest, inp) ||
- ip_addr_ismulticast(¤t_iphdr_dest)) {
- TCP_STATS_INC(tcp.proterr);
- TCP_STATS_INC(tcp.drop);
- snmp_inc_tcpinerrs();
- pbuf_free(p);
- return;
- }
-
-#if CHECKSUM_CHECK_TCP
- /* Verify TCP checksum. */
- if (inet_chksum_pseudo(p, ip_current_src_addr(), ip_current_dest_addr(),
- IP_PROTO_TCP, p->tot_len) != 0) {
- LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packet discarded due to failing checksum 0x%04"X16_F"\n",
- inet_chksum_pseudo(p, ip_current_src_addr(), ip_current_dest_addr(),
- IP_PROTO_TCP, p->tot_len)));
-#if TCP_DEBUG
- tcp_debug_print(tcphdr);
-#endif /* TCP_DEBUG */
- TCP_STATS_INC(tcp.chkerr);
- TCP_STATS_INC(tcp.drop);
- snmp_inc_tcpinerrs();
- pbuf_free(p);
- return;
- }
-#endif
-
- /* Move the payload pointer in the pbuf so that it points to the
- TCP data instead of the TCP header. */
- hdrlen = TCPH_HDRLEN(tcphdr);
- if(pbuf_header(p, -(hdrlen * 4))){
- /* drop short packets */
- LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: short packet\n"));
- TCP_STATS_INC(tcp.lenerr);
- TCP_STATS_INC(tcp.drop);
- snmp_inc_tcpinerrs();
- pbuf_free(p);
- return;
- }
-
- /* Convert fields in TCP header to host byte order. */
- tcphdr->src = ntohs(tcphdr->src);
- tcphdr->dest = ntohs(tcphdr->dest);
- seqno = tcphdr->seqno = ntohl(tcphdr->seqno);
- ackno = tcphdr->ackno = ntohl(tcphdr->ackno);
- tcphdr->wnd = ntohs(tcphdr->wnd);
-
- flags = TCPH_FLAGS(tcphdr);
- tcplen = p->tot_len + ((flags & (TCP_FIN | TCP_SYN)) ? 1 : 0);
-
- /* Demultiplex an incoming segment. First, we check if it is destined
- for an active connection. */
- prev = NULL;
-
-
- for(pcb = tcp_active_pcbs; pcb != NULL; pcb = pcb->next) {
- LWIP_ASSERT("tcp_input: active pcb->state != CLOSED", pcb->state != CLOSED);
- LWIP_ASSERT("tcp_input: active pcb->state != TIME-WAIT", pcb->state != TIME_WAIT);
- LWIP_ASSERT("tcp_input: active pcb->state != LISTEN", pcb->state != LISTEN);
- if (pcb->remote_port == tcphdr->src &&
- pcb->local_port == tcphdr->dest &&
- ip_addr_cmp(&(pcb->remote_ip), ¤t_iphdr_src) &&
- ip_addr_cmp(&(pcb->local_ip), ¤t_iphdr_dest)) {
-
- /* Move this PCB to the front of the list so that subsequent
- lookups will be faster (we exploit locality in TCP segment
- arrivals). */
- LWIP_ASSERT("tcp_input: pcb->next != pcb (before cache)", pcb->next != pcb);
- if (prev != NULL) {
- prev->next = pcb->next;
- pcb->next = tcp_active_pcbs;
- tcp_active_pcbs = pcb;
- }
- LWIP_ASSERT("tcp_input: pcb->next != pcb (after cache)", pcb->next != pcb);
- break;
- }
- prev = pcb;
- }
-
- if (pcb == NULL) {
- /* If it did not go to an active connection, we check the connections
- in the TIME-WAIT state. */
- for(pcb = tcp_tw_pcbs; pcb != NULL; pcb = pcb->next) {
- LWIP_ASSERT("tcp_input: TIME-WAIT pcb->state == TIME-WAIT", pcb->state == TIME_WAIT);
- if (pcb->remote_port == tcphdr->src &&
- pcb->local_port == tcphdr->dest &&
- ip_addr_cmp(&(pcb->remote_ip), ¤t_iphdr_src) &&
- ip_addr_cmp(&(pcb->local_ip), ¤t_iphdr_dest)) {
- /* We don't really care enough to move this PCB to the front
- of the list since we are not very likely to receive that
- many segments for connections in TIME-WAIT. */
- LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packed for TIME_WAITing connection.\n"));
- tcp_timewait_input(pcb);
- pbuf_free(p);
- return;
- }
- }
-
- /* Finally, if we still did not get a match, we check all PCBs that
- are LISTENing for incoming connections. */
- prev = NULL;
- for(lpcb = tcp_listen_pcbs.listen_pcbs; lpcb != NULL; lpcb = lpcb->next) {
- if (lpcb->local_port == tcphdr->dest) {
-#if SO_REUSE
- if (ip_addr_cmp(&(lpcb->local_ip), ¤t_iphdr_dest)) {
- /* found an exact match */
- break;
- } else if(ip_addr_isany(&(lpcb->local_ip))) {
- /* found an ANY-match */
- lpcb_any = lpcb;
- lpcb_prev = prev;
- }
-#else /* SO_REUSE */
- if (ip_addr_cmp(&(lpcb->local_ip), ¤t_iphdr_dest) ||
- ip_addr_isany(&(lpcb->local_ip))) {
- /* found a match */
- break;
- }
-#endif /* SO_REUSE */
- }
- prev = (struct tcp_pcb *)lpcb;
- }
-#if SO_REUSE
- /* first try specific local IP */
- if (lpcb == NULL) {
- /* only pass to ANY if no specific local IP has been found */
- lpcb = lpcb_any;
- prev = lpcb_prev;
- }
-#endif /* SO_REUSE */
- if (lpcb != NULL) {
- /* Move this PCB to the front of the list so that subsequent
- lookups will be faster (we exploit locality in TCP segment
- arrivals). */
- if (prev != NULL) {
- ((struct tcp_pcb_listen *)prev)->next = lpcb->next;
- /* our successor is the remainder of the listening list */
- lpcb->next = tcp_listen_pcbs.listen_pcbs;
- /* put this listening pcb at the head of the listening list */
- tcp_listen_pcbs.listen_pcbs = lpcb;
- }
-
- LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packed for LISTENing connection.\n"));
- tcp_listen_input(lpcb);
- pbuf_free(p);
- return;
- }
- }
-
-#if TCP_INPUT_DEBUG
- LWIP_DEBUGF(TCP_INPUT_DEBUG, ("+-+-+-+-+-+-+-+-+-+-+-+-+-+- tcp_input: flags "));
- tcp_debug_print_flags(TCPH_FLAGS(tcphdr));
- LWIP_DEBUGF(TCP_INPUT_DEBUG, ("-+-+-+-+-+-+-+-+-+-+-+-+-+-+\n"));
-#endif /* TCP_INPUT_DEBUG */
-
-
- if (pcb != NULL) {
- /* The incoming segment belongs to a connection. */
-#if TCP_INPUT_DEBUG
-#if TCP_DEBUG
- tcp_debug_print_state(pcb->state);
-#endif /* TCP_DEBUG */
-#endif /* TCP_INPUT_DEBUG */
-
- /* Set up a tcp_seg structure. */
- inseg.next = NULL;
- inseg.len = p->tot_len;
- inseg.dataptr = p->payload;
- inseg.p = p;
- inseg.tcphdr = tcphdr;
-
- recv_data = NULL;
- recv_flags = 0;
-
- /* If there is data which was previously "refused" by upper layer */
- if (pcb->refused_data != NULL) {
- /* Notify again application with data previously received. */
- LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: notify kept packet\n"));
- TCP_EVENT_RECV(pcb, pcb->refused_data, ERR_OK, err);
- if (err == ERR_OK) {
- pcb->refused_data = NULL;
- } else {
- /* if err == ERR_ABRT, 'pcb' is already deallocated */
- /* drop incoming packets, because pcb is "full" */
- LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: drop incoming packets, because pcb is \"full\"\n"));
- TCP_STATS_INC(tcp.drop);
- snmp_inc_tcpinerrs();
- pbuf_free(p);
- return;
- }
- }
- tcp_input_pcb = pcb;
- err = tcp_process(pcb);
- /* A return value of ERR_ABRT means that tcp_abort() was called
- and that the pcb has been freed. If so, we don't do anything. */
- if (err != ERR_ABRT) {
- if (recv_flags & TF_RESET) {
- /* TF_RESET means that the connection was reset by the other
- end. We then call the error callback to inform the
- application that the connection is dead before we
- deallocate the PCB. */
- TCP_EVENT_ERR(pcb->errf, pcb->callback_arg, ERR_RST);
- tcp_pcb_remove(&tcp_active_pcbs, pcb);
- memp_free(MEMP_TCP_PCB, pcb);
- } else if (recv_flags & TF_CLOSED) {
- /* The connection has been closed and we will deallocate the
- PCB. */
- tcp_pcb_remove(&tcp_active_pcbs, pcb);
- memp_free(MEMP_TCP_PCB, pcb);
- } else {
- err = ERR_OK;
- /* If the application has registered a "sent" function to be
- called when new send buffer space is available, we call it
- now. */
- if (pcb->acked > 0) {
- TCP_EVENT_SENT(pcb, pcb->acked, err);
- if (err == ERR_ABRT) {
- goto aborted;
- }
- }
-
- if (recv_data != NULL) {
- if (pcb->flags & TF_RXCLOSED) {
- /* received data although already closed -> abort (send RST) to
- notify the remote host that not all data has been processed */
- pbuf_free(recv_data);
- tcp_abort(pcb);
- goto aborted;
- }
- if (flags & TCP_PSH) {
- recv_data->flags |= PBUF_FLAG_PUSH;
- }
-
- /* Notify application that data has been received. */
- TCP_EVENT_RECV(pcb, recv_data, ERR_OK, err);
- if (err == ERR_ABRT) {
- goto aborted;
- }
-
- /* If the upper layer can't receive this data, store it */
- if (err != ERR_OK) {
- pcb->refused_data = recv_data;
- LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: keep incoming packet, because pcb is \"full\"\n"));
- }
- }
-
- /* If a FIN segment was received, we call the callback
- function with a NULL buffer to indicate EOF. */
- if (recv_flags & TF_GOT_FIN) {
- /* correct rcv_wnd as the application won't call tcp_recved()
- for the FIN's seqno */
- if (pcb->rcv_wnd != TCP_WND) {
- pcb->rcv_wnd++;
- }
- TCP_EVENT_CLOSED(pcb, err);
- if (err == ERR_ABRT) {
- goto aborted;
- }
- }
-
- tcp_input_pcb = NULL;
- /* Try to send something out. */
- tcp_output(pcb);
-#if TCP_INPUT_DEBUG
-#if TCP_DEBUG
- tcp_debug_print_state(pcb->state);
-#endif /* TCP_DEBUG */
-#endif /* TCP_INPUT_DEBUG */
- }
- }
- /* Jump target if pcb has been aborted in a callback (by calling tcp_abort()).
- Below this line, 'pcb' may not be dereferenced! */
-aborted:
- tcp_input_pcb = NULL;
- recv_data = NULL;
-
- /* give up our reference to inseg.p */
- if (inseg.p != NULL)
- {
- pbuf_free(inseg.p);
- inseg.p = NULL;
- }
- } else {
-
- /* If no matching PCB was found, send a TCP RST (reset) to the
- sender. */
- LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_input: no PCB match found, resetting.\n"));
- if (!(TCPH_FLAGS(tcphdr) & TCP_RST)) {
- TCP_STATS_INC(tcp.proterr);
- TCP_STATS_INC(tcp.drop);
- tcp_rst(ackno, seqno + tcplen,
- ip_current_dest_addr(), ip_current_src_addr(),
- tcphdr->dest, tcphdr->src);
- }
- pbuf_free(p);
- }
-
- LWIP_ASSERT("tcp_input: tcp_pcbs_sane()", tcp_pcbs_sane());
- PERF_STOP("tcp_input");
-}
-
-/**
- * Called by tcp_input() when a segment arrives for a listening
- * connection (from tcp_input()).
- *
- * @param pcb the tcp_pcb_listen for which a segment arrived
- * @return ERR_OK if the segment was processed
- * another err_t on error
- *
- * @note the return value is not (yet?) used in tcp_input()
- * @note the segment which arrived is saved in global variables, therefore only the pcb
- * involved is passed as a parameter to this function
- */
-static err_t
-tcp_listen_input(struct tcp_pcb_listen *pcb)
-{
- struct tcp_pcb *npcb;
- err_t rc;
-
- /* In the LISTEN state, we check for incoming SYN segments,
- creates a new PCB, and responds with a SYN|ACK. */
- if (flags & TCP_ACK) {
- /* For incoming segments with the ACK flag set, respond with a
- RST. */
- LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_listen_input: ACK in LISTEN, sending reset\n"));
- tcp_rst(ackno + 1, seqno + tcplen,
- ip_current_dest_addr(), ip_current_src_addr(),
- tcphdr->dest, tcphdr->src);
- } else if (flags & TCP_SYN) {
- LWIP_DEBUGF(TCP_DEBUG, ("TCP connection request %"U16_F" -> %"U16_F".\n", tcphdr->src, tcphdr->dest));
-#if TCP_LISTEN_BACKLOG
- if (pcb->accepts_pending >= pcb->backlog) {
- LWIP_DEBUGF(TCP_DEBUG, ("tcp_listen_input: listen backlog exceeded for port %"U16_F"\n", tcphdr->dest));
- return ERR_ABRT;
- }
-#endif /* TCP_LISTEN_BACKLOG */
- npcb = tcp_alloc(pcb->prio);
- /* If a new PCB could not be created (probably due to lack of memory),
- we don't do anything, but rely on the sender will retransmit the
- SYN at a time when we have more memory available. */
- if (npcb == NULL) {
- LWIP_DEBUGF(TCP_DEBUG, ("tcp_listen_input: could not allocate PCB\n"));
- TCP_STATS_INC(tcp.memerr);
- return ERR_MEM;
- }
-#if TCP_LISTEN_BACKLOG
- pcb->accepts_pending++;
-#endif /* TCP_LISTEN_BACKLOG */
- /* Set up the new PCB. */
- ip_addr_copy(npcb->local_ip, current_iphdr_dest);
- npcb->local_port = pcb->local_port;
- ip_addr_copy(npcb->remote_ip, current_iphdr_src);
- npcb->remote_port = tcphdr->src;
- npcb->state = SYN_RCVD;
- npcb->rcv_nxt = seqno + 1;
- npcb->rcv_ann_right_edge = npcb->rcv_nxt;
- npcb->snd_wnd = tcphdr->wnd;
- npcb->ssthresh = npcb->snd_wnd;
- npcb->snd_wl1 = seqno - 1;/* initialise to seqno-1 to force window update */
- npcb->callback_arg = pcb->callback_arg;
-#if LWIP_CALLBACK_API
- npcb->accept = pcb->accept;
-#endif /* LWIP_CALLBACK_API */
- /* inherit socket options */
- npcb->so_options = pcb->so_options & SOF_INHERITED;
- /* Register the new PCB so that we can begin receiving segments
- for it. */
- TCP_REG(&tcp_active_pcbs, npcb);
-
- /* Parse any options in the SYN. */
- tcp_parseopt(npcb);
-#if TCP_CALCULATE_EFF_SEND_MSS
- npcb->mss = tcp_eff_send_mss(npcb->mss, &(npcb->remote_ip));
-#endif /* TCP_CALCULATE_EFF_SEND_MSS */
-
- snmp_inc_tcppassiveopens();
-
- /* Send a SYN|ACK together with the MSS option. */
- rc = tcp_enqueue_flags(npcb, TCP_SYN | TCP_ACK);
- if (rc != ERR_OK) {
- tcp_abandon(npcb, 0);
- return rc;
- }
- return tcp_output(npcb);
- }
- return ERR_OK;
-}
-
-/**
- * Called by tcp_input() when a segment arrives for a connection in
- * TIME_WAIT.
- *
- * @param pcb the tcp_pcb for which a segment arrived
- *
- * @note the segment which arrived is saved in global variables, therefore only the pcb
- * involved is passed as a parameter to this function
- */
-static err_t
-tcp_timewait_input(struct tcp_pcb *pcb)
-{
- /* RFC 1337: in TIME_WAIT, ignore RST and ACK FINs + any 'acceptable' segments */
- /* RFC 793 3.9 Event Processing - Segment Arrives:
- * - first check sequence number - we skip that one in TIME_WAIT (always
- * acceptable since we only send ACKs)
- * - second check the RST bit (... return) */
- if (flags & TCP_RST) {
- return ERR_OK;
- }
- /* - fourth, check the SYN bit, */
- if (flags & TCP_SYN) {
- /* If an incoming segment is not acceptable, an acknowledgment
- should be sent in reply */
- if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt, pcb->rcv_nxt+pcb->rcv_wnd)) {
- /* If the SYN is in the window it is an error, send a reset */
- tcp_rst(ackno, seqno + tcplen, ip_current_dest_addr(), ip_current_src_addr(),
- tcphdr->dest, tcphdr->src);
- return ERR_OK;
- }
- } else if (flags & TCP_FIN) {
- /* - eighth, check the FIN bit: Remain in the TIME-WAIT state.
- Restart the 2 MSL time-wait timeout.*/
- pcb->tmr = tcp_ticks;
- }
-
- if ((tcplen > 0)) {
- /* Acknowledge data, FIN or out-of-window SYN */
- pcb->flags |= TF_ACK_NOW;
- return tcp_output(pcb);
- }
- return ERR_OK;
-}
-
-/**
- * Implements the TCP state machine. Called by tcp_input. In some
- * states tcp_receive() is called to receive data. The tcp_seg
- * argument will be freed by the caller (tcp_input()) unless the
- * recv_data pointer in the pcb is set.
- *
- * @param pcb the tcp_pcb for which a segment arrived
- *
- * @note the segment which arrived is saved in global variables, therefore only the pcb
- * involved is passed as a parameter to this function
- */
-static err_t
-tcp_process(struct tcp_pcb *pcb)
-{
- struct tcp_seg *rseg;
- u8_t acceptable = 0;
- err_t err;
-
- err = ERR_OK;
-
- /* Process incoming RST segments. */
- if (flags & TCP_RST) {
- /* First, determine if the reset is acceptable. */
- if (pcb->state == SYN_SENT) {
- if (ackno == pcb->snd_nxt) {
- acceptable = 1;
- }
- } else {
- if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt,
- pcb->rcv_nxt+pcb->rcv_wnd)) {
- acceptable = 1;
- }
- }
-
- if (acceptable) {
- LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_process: Connection RESET\n"));
- LWIP_ASSERT("tcp_input: pcb->state != CLOSED", pcb->state != CLOSED);
- recv_flags |= TF_RESET;
- pcb->flags &= ~TF_ACK_DELAY;
- return ERR_RST;
- } else {
- LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_process: unacceptable reset seqno %"U32_F" rcv_nxt %"U32_F"\n",
- seqno, pcb->rcv_nxt));
- LWIP_DEBUGF(TCP_DEBUG, ("tcp_process: unacceptable reset seqno %"U32_F" rcv_nxt %"U32_F"\n",
- seqno, pcb->rcv_nxt));
- return ERR_OK;
- }
- }
-
- if ((flags & TCP_SYN) && (pcb->state != SYN_SENT && pcb->state != SYN_RCVD)) {
- /* Cope with new connection attempt after remote end crashed */
- tcp_ack_now(pcb);
- return ERR_OK;
- }
-
- if ((pcb->flags & TF_RXCLOSED) == 0) {
- /* Update the PCB (in)activity timer unless rx is closed (see tcp_shutdown) */
- pcb->tmr = tcp_ticks;
- }
- pcb->keep_cnt_sent = 0;
-
- tcp_parseopt(pcb);
-
- /* Do different things depending on the TCP state. */
- switch (pcb->state) {
- case SYN_SENT:
- LWIP_DEBUGF(TCP_INPUT_DEBUG, ("SYN-SENT: ackno %"U32_F" pcb->snd_nxt %"U32_F" unacked %"U32_F"\n", ackno,
- pcb->snd_nxt, ntohl(pcb->unacked->tcphdr->seqno)));
- /* received SYN ACK with expected sequence number? */
- if ((flags & TCP_ACK) && (flags & TCP_SYN)
- && ackno == ntohl(pcb->unacked->tcphdr->seqno) + 1) {
- pcb->snd_buf++;
- pcb->rcv_nxt = seqno + 1;
- pcb->rcv_ann_right_edge = pcb->rcv_nxt;
- pcb->lastack = ackno;
- pcb->snd_wnd = tcphdr->wnd;
- pcb->snd_wl1 = seqno - 1; /* initialise to seqno - 1 to force window update */
- pcb->state = ESTABLISHED;
-
-#if TCP_CALCULATE_EFF_SEND_MSS
- pcb->mss = tcp_eff_send_mss(pcb->mss, &(pcb->remote_ip));
-#endif /* TCP_CALCULATE_EFF_SEND_MSS */
-
- /* Set ssthresh again after changing pcb->mss (already set in tcp_connect
- * but for the default value of pcb->mss) */
- pcb->ssthresh = pcb->mss * 10;
-
- pcb->cwnd = ((pcb->cwnd == 1) ? (pcb->mss * 2) : pcb->mss);
- LWIP_ASSERT("pcb->snd_queuelen > 0", (pcb->snd_queuelen > 0));
- --pcb->snd_queuelen;
- LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_process: SYN-SENT --queuelen %"U16_F"\n", (u16_t)pcb->snd_queuelen));
- rseg = pcb->unacked;
- pcb->unacked = rseg->next;
-
- /* If there's nothing left to acknowledge, stop the retransmit
- timer, otherwise reset it to start again */
- if(pcb->unacked == NULL)
- pcb->rtime = -1;
- else {
- pcb->rtime = 0;
- pcb->nrtx = 0;
- }
-
- tcp_seg_free(rseg);
-
- /* Call the user specified function to call when sucessfully
- * connected. */
- TCP_EVENT_CONNECTED(pcb, ERR_OK, err);
- if (err == ERR_ABRT) {
- return ERR_ABRT;
- }
- tcp_ack_now(pcb);
- }
- /* received ACK? possibly a half-open connection */
- else if (flags & TCP_ACK) {
- /* send a RST to bring the other side in a non-synchronized state. */
- tcp_rst(ackno, seqno + tcplen, ip_current_dest_addr(), ip_current_src_addr(),
- tcphdr->dest, tcphdr->src);
- }
- break;
- case SYN_RCVD:
- if (flags & TCP_ACK) {
- /* expected ACK number? */
- if (TCP_SEQ_BETWEEN(ackno, pcb->lastack+1, pcb->snd_nxt)) {
- u16_t old_cwnd;
- pcb->state = ESTABLISHED;
- LWIP_DEBUGF(TCP_DEBUG, ("TCP connection established %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
-#if LWIP_CALLBACK_API
- LWIP_ASSERT("pcb->accept != NULL", pcb->accept != NULL);
-#endif
- /* Call the accept function. */
- TCP_EVENT_ACCEPT(pcb, ERR_OK, err);
- if (err != ERR_OK) {
- /* If the accept function returns with an error, we abort
- * the connection. */
- /* Already aborted? */
- if (err != ERR_ABRT) {
- tcp_abort(pcb);
- }
- return ERR_ABRT;
- }
- old_cwnd = pcb->cwnd;
- /* If there was any data contained within this ACK,
- * we'd better pass it on to the application as well. */
- tcp_receive(pcb);
-
- /* Prevent ACK for SYN to generate a sent event */
- if (pcb->acked != 0) {
- pcb->acked--;
- }
-
- pcb->cwnd = ((old_cwnd == 1) ? (pcb->mss * 2) : pcb->mss);
-
- if (recv_flags & TF_GOT_FIN) {
- tcp_ack_now(pcb);
- pcb->state = CLOSE_WAIT;
- }
- } else {
- /* incorrect ACK number, send RST */
- tcp_rst(ackno, seqno + tcplen, ip_current_dest_addr(), ip_current_src_addr(),
- tcphdr->dest, tcphdr->src);
- }
- } else if ((flags & TCP_SYN) && (seqno == pcb->rcv_nxt - 1)) {
- /* Looks like another copy of the SYN - retransmit our SYN-ACK */
- tcp_rexmit(pcb);
- }
- break;
- case CLOSE_WAIT:
- /* FALLTHROUGH */
- case ESTABLISHED:
- tcp_receive(pcb);
- if (recv_flags & TF_GOT_FIN) { /* passive close */
- tcp_ack_now(pcb);
- pcb->state = CLOSE_WAIT;
- }
- break;
- case FIN_WAIT_1:
- tcp_receive(pcb);
- if (recv_flags & TF_GOT_FIN) {
- if ((flags & TCP_ACK) && (ackno == pcb->snd_nxt)) {
- LWIP_DEBUGF(TCP_DEBUG,
- ("TCP connection closed: FIN_WAIT_1 %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
- tcp_ack_now(pcb);
- tcp_pcb_purge(pcb);
- TCP_RMV(&tcp_active_pcbs, pcb);
- pcb->state = TIME_WAIT;
- TCP_REG(&tcp_tw_pcbs, pcb);
- } else {
- tcp_ack_now(pcb);
- pcb->state = CLOSING;
- }
- } else if ((flags & TCP_ACK) && (ackno == pcb->snd_nxt)) {
- pcb->state = FIN_WAIT_2;
- }
- break;
- case FIN_WAIT_2:
- tcp_receive(pcb);
- if (recv_flags & TF_GOT_FIN) {
- LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: FIN_WAIT_2 %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
- tcp_ack_now(pcb);
- tcp_pcb_purge(pcb);
- TCP_RMV(&tcp_active_pcbs, pcb);
- pcb->state = TIME_WAIT;
- TCP_REG(&tcp_tw_pcbs, pcb);
- }
- break;
- case CLOSING:
- tcp_receive(pcb);
- if (flags & TCP_ACK && ackno == pcb->snd_nxt) {
- LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: CLOSING %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
- tcp_pcb_purge(pcb);
- TCP_RMV(&tcp_active_pcbs, pcb);
- pcb->state = TIME_WAIT;
- TCP_REG(&tcp_tw_pcbs, pcb);
- }
- break;
- case LAST_ACK:
- tcp_receive(pcb);
- if (flags & TCP_ACK && ackno == pcb->snd_nxt) {
- LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: LAST_ACK %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
- /* bugfix #21699: don't set pcb->state to CLOSED here or we risk leaking segments */
- recv_flags |= TF_CLOSED;
- }
- break;
- default:
- break;
- }
- return ERR_OK;
-}
-
-#if TCP_QUEUE_OOSEQ
-/**
- * Insert segment into the list (segments covered with new one will be deleted)
- *
- * Called from tcp_receive()
- */
-static void
-tcp_oos_insert_segment(struct tcp_seg *cseg, struct tcp_seg *next)
-{
- struct tcp_seg *old_seg;
-
- if (TCPH_FLAGS(cseg->tcphdr) & TCP_FIN) {
- /* received segment overlaps all following segments */
- tcp_segs_free(next);
- next = NULL;
- }
- else {
- /* delete some following segments
- oos queue may have segments with FIN flag */
- while (next &&
- TCP_SEQ_GEQ((seqno + cseg->len),
- (next->tcphdr->seqno + next->len))) {
- /* cseg with FIN already processed */
- if (TCPH_FLAGS(next->tcphdr) & TCP_FIN) {
- TCPH_SET_FLAG(cseg->tcphdr, TCP_FIN);
- }
- old_seg = next;
- next = next->next;
- tcp_seg_free(old_seg);
- }
- if (next &&
- TCP_SEQ_GT(seqno + cseg->len, next->tcphdr->seqno)) {
- /* We need to trim the incoming segment. */
- cseg->len = (u16_t)(next->tcphdr->seqno - seqno);
- pbuf_realloc(cseg->p, cseg->len);
- }
- }
- cseg->next = next;
-}
-#endif /* TCP_QUEUE_OOSEQ */
-
-/**
- * Called by tcp_process. Checks if the given segment is an ACK for outstanding
- * data, and if so frees the memory of the buffered data. Next, is places the
- * segment on any of the receive queues (pcb->recved or pcb->ooseq). If the segment
- * is buffered, the pbuf is referenced by pbuf_ref so that it will not be freed until
- * i it has been removed from the buffer.
- *
- * If the incoming segment constitutes an ACK for a segment that was used for RTT
- * estimation, the RTT is estimated here as well.
- *
- * Called from tcp_process().
- */
-static void
-tcp_receive(struct tcp_pcb *pcb)
-{
- struct tcp_seg *next;
-#if TCP_QUEUE_OOSEQ
- struct tcp_seg *prev, *cseg;
-#endif /* TCP_QUEUE_OOSEQ */
- struct pbuf *p;
- s32_t off;
- s16_t m;
- u32_t right_wnd_edge;
- u16_t new_tot_len;
- int found_dupack = 0;
-
- if (flags & TCP_ACK) {
- right_wnd_edge = pcb->snd_wnd + pcb->snd_wl2;
-
- /* Update window. */
- if (TCP_SEQ_LT(pcb->snd_wl1, seqno) ||
- (pcb->snd_wl1 == seqno && TCP_SEQ_LT(pcb->snd_wl2, ackno)) ||
- (pcb->snd_wl2 == ackno && tcphdr->wnd > pcb->snd_wnd)) {
- pcb->snd_wnd = tcphdr->wnd;
- pcb->snd_wl1 = seqno;
- pcb->snd_wl2 = ackno;
- if (pcb->snd_wnd > 0 && pcb->persist_backoff > 0) {
- pcb->persist_backoff = 0;
- }
- LWIP_DEBUGF(TCP_WND_DEBUG, ("tcp_receive: window update %"U16_F"\n", pcb->snd_wnd));
-#if TCP_WND_DEBUG
- } else {
- if (pcb->snd_wnd != tcphdr->wnd) {
- LWIP_DEBUGF(TCP_WND_DEBUG,
- ("tcp_receive: no window update lastack %"U32_F" ackno %"
- U32_F" wl1 %"U32_F" seqno %"U32_F" wl2 %"U32_F"\n",
- pcb->lastack, ackno, pcb->snd_wl1, seqno, pcb->snd_wl2));
- }
-#endif /* TCP_WND_DEBUG */
- }
-
- /* (From Stevens TCP/IP Illustrated Vol II, p970.) Its only a
- * duplicate ack if:
- * 1) It doesn't ACK new data
- * 2) length of received packet is zero (i.e. no payload)
- * 3) the advertised window hasn't changed
- * 4) There is outstanding unacknowledged data (retransmission timer running)
- * 5) The ACK is == biggest ACK sequence number so far seen (snd_una)
- *
- * If it passes all five, should process as a dupack:
- * a) dupacks < 3: do nothing
- * b) dupacks == 3: fast retransmit
- * c) dupacks > 3: increase cwnd
- *
- * If it only passes 1-3, should reset dupack counter (and add to
- * stats, which we don't do in lwIP)
- *
- * If it only passes 1, should reset dupack counter
- *
- */
-
- /* Clause 1 */
- if (TCP_SEQ_LEQ(ackno, pcb->lastack)) {
- pcb->acked = 0;
- /* Clause 2 */
- if (tcplen == 0) {
- /* Clause 3 */
- if (pcb->snd_wl2 + pcb->snd_wnd == right_wnd_edge){
- /* Clause 4 */
- if (pcb->rtime >= 0) {
- /* Clause 5 */
- if (pcb->lastack == ackno) {
- found_dupack = 1;
- if (pcb->dupacks + 1 > pcb->dupacks)
- ++pcb->dupacks;
- if (pcb->dupacks > 3) {
- /* Inflate the congestion window, but not if it means that
- the value overflows. */
- if ((u16_t)(pcb->cwnd + pcb->mss) > pcb->cwnd) {
- pcb->cwnd += pcb->mss;
- }
- } else if (pcb->dupacks == 3) {
- /* Do fast retransmit */
- tcp_rexmit_fast(pcb);
- }
- }
- }
- }
- }
- /* If Clause (1) or more is true, but not a duplicate ack, reset
- * count of consecutive duplicate acks */
- if (!found_dupack) {
- pcb->dupacks = 0;
- }
- } else if (TCP_SEQ_BETWEEN(ackno, pcb->lastack+1, pcb->snd_nxt)){
- /* We come here when the ACK acknowledges new data. */
-
- /* Reset the "IN Fast Retransmit" flag, since we are no longer
- in fast retransmit. Also reset the congestion window to the
- slow start threshold. */
- if (pcb->flags & TF_INFR) {
- pcb->flags &= ~TF_INFR;
- pcb->cwnd = pcb->ssthresh;
- }
-
- /* Reset the number of retransmissions. */
- pcb->nrtx = 0;
-
- /* Reset the retransmission time-out. */
- pcb->rto = (pcb->sa >> 3) + pcb->sv;
-
- /* Update the send buffer space. Diff between the two can never exceed 64K? */
- pcb->acked = (u16_t)(ackno - pcb->lastack);
-
- pcb->snd_buf += pcb->acked;
-
- /* Reset the fast retransmit variables. */
- pcb->dupacks = 0;
- pcb->lastack = ackno;
-
- /* Update the congestion control variables (cwnd and
- ssthresh). */
- if (pcb->state >= ESTABLISHED) {
- if (pcb->cwnd < pcb->ssthresh) {
- if ((u16_t)(pcb->cwnd + pcb->mss) > pcb->cwnd) {
- pcb->cwnd += pcb->mss;
- }
- LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_receive: slow start cwnd %"U16_F"\n", pcb->cwnd));
- } else {
- u16_t new_cwnd = (pcb->cwnd + pcb->mss * pcb->mss / pcb->cwnd);
- if (new_cwnd > pcb->cwnd) {
- pcb->cwnd = new_cwnd;
- }
- LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_receive: congestion avoidance cwnd %"U16_F"\n", pcb->cwnd));
- }
- }
- LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: ACK for %"U32_F", unacked->seqno %"U32_F":%"U32_F"\n",
- ackno,
- pcb->unacked != NULL?
- ntohl(pcb->unacked->tcphdr->seqno): 0,
- pcb->unacked != NULL?
- ntohl(pcb->unacked->tcphdr->seqno) + TCP_TCPLEN(pcb->unacked): 0));
-
- /* Remove segment from the unacknowledged list if the incoming
- ACK acknowlegdes them. */
- while (pcb->unacked != NULL &&
- TCP_SEQ_LEQ(ntohl(pcb->unacked->tcphdr->seqno) +
- TCP_TCPLEN(pcb->unacked), ackno)) {
- LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: removing %"U32_F":%"U32_F" from pcb->unacked\n",
- ntohl(pcb->unacked->tcphdr->seqno),
- ntohl(pcb->unacked->tcphdr->seqno) +
- TCP_TCPLEN(pcb->unacked)));
-
- next = pcb->unacked;
- pcb->unacked = pcb->unacked->next;
-
- LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_receive: queuelen %"U16_F" ... ", (u16_t)pcb->snd_queuelen));
- LWIP_ASSERT("pcb->snd_queuelen >= pbuf_clen(next->p)", (pcb->snd_queuelen >= pbuf_clen(next->p)));
- /* Prevent ACK for FIN to generate a sent event */
- if ((pcb->acked != 0) && ((TCPH_FLAGS(next->tcphdr) & TCP_FIN) != 0)) {
- pcb->acked--;
- }
-
- pcb->snd_queuelen -= pbuf_clen(next->p);
- tcp_seg_free(next);
-
- LWIP_DEBUGF(TCP_QLEN_DEBUG, ("%"U16_F" (after freeing unacked)\n", (u16_t)pcb->snd_queuelen));
- if (pcb->snd_queuelen != 0) {
- LWIP_ASSERT("tcp_receive: valid queue length", pcb->unacked != NULL ||
- pcb->unsent != NULL);
- }
- }
-
- /* If there's nothing left to acknowledge, stop the retransmit
- timer, otherwise reset it to start again */
- if(pcb->unacked == NULL)
- pcb->rtime = -1;
- else
- pcb->rtime = 0;
-
- pcb->polltmr = 0;
- } else {
- /* Fix bug bug #21582: out of sequence ACK, didn't really ack anything */
- pcb->acked = 0;
- }
-
- /* We go through the ->unsent list to see if any of the segments
- on the list are acknowledged by the ACK. This may seem
- strange since an "unsent" segment shouldn't be acked. The
- rationale is that lwIP puts all outstanding segments on the
- ->unsent list after a retransmission, so these segments may
- in fact have been sent once. */
- while (pcb->unsent != NULL &&
- TCP_SEQ_BETWEEN(ackno, ntohl(pcb->unsent->tcphdr->seqno) +
- TCP_TCPLEN(pcb->unsent), pcb->snd_nxt)) {
- LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: removing %"U32_F":%"U32_F" from pcb->unsent\n",
- ntohl(pcb->unsent->tcphdr->seqno), ntohl(pcb->unsent->tcphdr->seqno) +
- TCP_TCPLEN(pcb->unsent)));
-
- next = pcb->unsent;
- pcb->unsent = pcb->unsent->next;
- LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_receive: queuelen %"U16_F" ... ", (u16_t)pcb->snd_queuelen));
- LWIP_ASSERT("pcb->snd_queuelen >= pbuf_clen(next->p)", (pcb->snd_queuelen >= pbuf_clen(next->p)));
- /* Prevent ACK for FIN to generate a sent event */
- if ((pcb->acked != 0) && ((TCPH_FLAGS(next->tcphdr) & TCP_FIN) != 0)) {
- pcb->acked--;
- }
- pcb->snd_queuelen -= pbuf_clen(next->p);
- tcp_seg_free(next);
- LWIP_DEBUGF(TCP_QLEN_DEBUG, ("%"U16_F" (after freeing unsent)\n", (u16_t)pcb->snd_queuelen));
- if (pcb->snd_queuelen != 0) {
- LWIP_ASSERT("tcp_receive: valid queue length",
- pcb->unacked != NULL || pcb->unsent != NULL);
- }
- }
- /* End of ACK for new data processing. */
-
- LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: pcb->rttest %"U32_F" rtseq %"U32_F" ackno %"U32_F"\n",
- pcb->rttest, pcb->rtseq, ackno));
-
- /* RTT estimation calculations. This is done by checking if the
- incoming segment acknowledges the segment we use to take a
- round-trip time measurement. */
- if (pcb->rttest && TCP_SEQ_LT(pcb->rtseq, ackno)) {
- /* diff between this shouldn't exceed 32K since this are tcp timer ticks
- and a round-trip shouldn't be that long... */
- m = (s16_t)(tcp_ticks - pcb->rttest);
-
- LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: experienced rtt %"U16_F" ticks (%"U16_F" msec).\n",
- m, m * TCP_SLOW_INTERVAL));
-
- /* This is taken directly from VJs original code in his paper */
- m = m - (pcb->sa >> 3);
- pcb->sa += m;
- if (m < 0) {
- m = -m;
- }
- m = m - (pcb->sv >> 2);
- pcb->sv += m;
- pcb->rto = (pcb->sa >> 3) + pcb->sv;
-
- LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_receive: RTO %"U16_F" (%"U16_F" milliseconds)\n",
- pcb->rto, pcb->rto * TCP_SLOW_INTERVAL));
-
- pcb->rttest = 0;
- }
- }
-
- /* If the incoming segment contains data, we must process it
- further. */
- if (tcplen > 0) {
- /* This code basically does three things:
-
- +) If the incoming segment contains data that is the next
- in-sequence data, this data is passed to the application. This
- might involve trimming the first edge of the data. The rcv_nxt
- variable and the advertised window are adjusted.
-
- +) If the incoming segment has data that is above the next
- sequence number expected (->rcv_nxt), the segment is placed on
- the ->ooseq queue. This is done by finding the appropriate
- place in the ->ooseq queue (which is ordered by sequence
- number) and trim the segment in both ends if needed. An
- immediate ACK is sent to indicate that we received an
- out-of-sequence segment.
-
- +) Finally, we check if the first segment on the ->ooseq queue
- now is in sequence (i.e., if rcv_nxt >= ooseq->seqno). If
- rcv_nxt > ooseq->seqno, we must trim the first edge of the
- segment on ->ooseq before we adjust rcv_nxt. The data in the
- segments that are now on sequence are chained onto the
- incoming segment so that we only need to call the application
- once.
- */
-
- /* First, we check if we must trim the first edge. We have to do
- this if the sequence number of the incoming segment is less
- than rcv_nxt, and the sequence number plus the length of the
- segment is larger than rcv_nxt. */
- /* if (TCP_SEQ_LT(seqno, pcb->rcv_nxt)){
- if (TCP_SEQ_LT(pcb->rcv_nxt, seqno + tcplen)) {*/
- if (TCP_SEQ_BETWEEN(pcb->rcv_nxt, seqno + 1, seqno + tcplen - 1)){
- /* Trimming the first edge is done by pushing the payload
- pointer in the pbuf downwards. This is somewhat tricky since
- we do not want to discard the full contents of the pbuf up to
- the new starting point of the data since we have to keep the
- TCP header which is present in the first pbuf in the chain.
-
- What is done is really quite a nasty hack: the first pbuf in
- the pbuf chain is pointed to by inseg.p. Since we need to be
- able to deallocate the whole pbuf, we cannot change this
- inseg.p pointer to point to any of the later pbufs in the
- chain. Instead, we point the ->payload pointer in the first
- pbuf to data in one of the later pbufs. We also set the
- inseg.data pointer to point to the right place. This way, the
- ->p pointer will still point to the first pbuf, but the
- ->p->payload pointer will point to data in another pbuf.
-
- After we are done with adjusting the pbuf pointers we must
- adjust the ->data pointer in the seg and the segment
- length.*/
-
- off = pcb->rcv_nxt - seqno;
- p = inseg.p;
- LWIP_ASSERT("inseg.p != NULL", inseg.p);
- LWIP_ASSERT("insane offset!", (off < 0x7fff));
- if (inseg.p->len < off) {
- LWIP_ASSERT("pbuf too short!", (((s32_t)inseg.p->tot_len) >= off));
- new_tot_len = (u16_t)(inseg.p->tot_len - off);
- while (p->len < off) {
- off -= p->len;
- /* KJM following line changed (with addition of new_tot_len var)
- to fix bug #9076
- inseg.p->tot_len -= p->len; */
- p->tot_len = new_tot_len;
- p->len = 0;
- p = p->next;
- }
- if(pbuf_header(p, (s16_t)-off)) {
- /* Do we need to cope with this failing? Assert for now */
- LWIP_ASSERT("pbuf_header failed", 0);
- }
- } else {
- if(pbuf_header(inseg.p, (s16_t)-off)) {
- /* Do we need to cope with this failing? Assert for now */
- LWIP_ASSERT("pbuf_header failed", 0);
- }
- }
- /* KJM following line changed to use p->payload rather than inseg->p->payload
- to fix bug #9076 */
- inseg.dataptr = p->payload;
- inseg.len -= (u16_t)(pcb->rcv_nxt - seqno);
- inseg.tcphdr->seqno = seqno = pcb->rcv_nxt;
- }
- else {
- if (TCP_SEQ_LT(seqno, pcb->rcv_nxt)){
- /* the whole segment is < rcv_nxt */
- /* must be a duplicate of a packet that has already been correctly handled */
-
- LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: duplicate seqno %"U32_F"\n", seqno));
- tcp_ack_now(pcb);
- }
- }
-
- /* The sequence number must be within the window (above rcv_nxt
- and below rcv_nxt + rcv_wnd) in order to be further
- processed. */
- if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt,
- pcb->rcv_nxt + pcb->rcv_wnd - 1)){
- if (pcb->rcv_nxt == seqno) {
- /* The incoming segment is the next in sequence. We check if
- we have to trim the end of the segment and update rcv_nxt
- and pass the data to the application. */
- tcplen = TCP_TCPLEN(&inseg);
-
- if (tcplen > pcb->rcv_wnd) {
- LWIP_DEBUGF(TCP_INPUT_DEBUG,
- ("tcp_receive: other end overran receive window"
- "seqno %"U32_F" len %"U16_F" right edge %"U32_F"\n",
- seqno, tcplen, pcb->rcv_nxt + pcb->rcv_wnd));
- if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
- /* Must remove the FIN from the header as we're trimming
- * that byte of sequence-space from the packet */
- TCPH_FLAGS_SET(inseg.tcphdr, TCPH_FLAGS(inseg.tcphdr) &~ TCP_FIN);
- }
- /* Adjust length of segment to fit in the window. */
- inseg.len = pcb->rcv_wnd;
- if (TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) {
- inseg.len -= 1;
- }
- pbuf_realloc(inseg.p, inseg.len);
- tcplen = TCP_TCPLEN(&inseg);
- LWIP_ASSERT("tcp_receive: segment not trimmed correctly to rcv_wnd\n",
- (seqno + tcplen) == (pcb->rcv_nxt + pcb->rcv_wnd));
- }
-#if TCP_QUEUE_OOSEQ
- /* Received in-sequence data, adjust ooseq data if:
- - FIN has been received or
- - inseq overlaps with ooseq */
- if (pcb->ooseq != NULL) {
- if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
- LWIP_DEBUGF(TCP_INPUT_DEBUG,
- ("tcp_receive: received in-order FIN, binning ooseq queue\n"));
- /* Received in-order FIN means anything that was received
- * out of order must now have been received in-order, so
- * bin the ooseq queue */
- while (pcb->ooseq != NULL) {
- struct tcp_seg *old_ooseq = pcb->ooseq;
- pcb->ooseq = pcb->ooseq->next;
- tcp_seg_free(old_ooseq);
- }
- }
- else {
- next = pcb->ooseq;
- /* Remove all segments on ooseq that are covered by inseg already.
- * FIN is copied from ooseq to inseg if present. */
- while (next &&
- TCP_SEQ_GEQ(seqno + tcplen,
- next->tcphdr->seqno + next->len)) {
- /* inseg cannot have FIN here (already processed above) */
- if (TCPH_FLAGS(next->tcphdr) & TCP_FIN &&
- (TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) == 0) {
- TCPH_SET_FLAG(inseg.tcphdr, TCP_FIN);
- tcplen = TCP_TCPLEN(&inseg);
- }
- prev = next;
- next = next->next;
- tcp_seg_free(prev);
- }
- /* Now trim right side of inseg if it overlaps with the first
- * segment on ooseq */
- if (next &&
- TCP_SEQ_GT(seqno + tcplen,
- next->tcphdr->seqno)) {
- /* inseg cannot have FIN here (already processed above) */
- inseg.len = (u16_t)(next->tcphdr->seqno - seqno);
- if (TCPH_FLAGS(inseg.tcphdr) & TCP_SYN) {
- inseg.len -= 1;
- }
- pbuf_realloc(inseg.p, inseg.len);
- tcplen = TCP_TCPLEN(&inseg);
- LWIP_ASSERT("tcp_receive: segment not trimmed correctly to ooseq queue\n",
- (seqno + tcplen) == next->tcphdr->seqno);
- }
- pcb->ooseq = next;
- }
- }
-#endif /* TCP_QUEUE_OOSEQ */
-
- pcb->rcv_nxt = seqno + tcplen;
-
- /* Update the receiver's (our) window. */
- LWIP_ASSERT("tcp_receive: tcplen > rcv_wnd\n", pcb->rcv_wnd >= tcplen);
- pcb->rcv_wnd -= tcplen;
-
- tcp_update_rcv_ann_wnd(pcb);
-
- /* If there is data in the segment, we make preparations to
- pass this up to the application. The ->recv_data variable
- is used for holding the pbuf that goes to the
- application. The code for reassembling out-of-sequence data
- chains its data on this pbuf as well.
-
- If the segment was a FIN, we set the TF_GOT_FIN flag that will
- be used to indicate to the application that the remote side has
- closed its end of the connection. */
- if (inseg.p->tot_len > 0) {
- recv_data = inseg.p;
- /* Since this pbuf now is the responsibility of the
- application, we delete our reference to it so that we won't
- (mistakingly) deallocate it. */
- inseg.p = NULL;
- }
- if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
- LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: received FIN.\n"));
- recv_flags |= TF_GOT_FIN;
- }
-
-#if TCP_QUEUE_OOSEQ
- /* We now check if we have segments on the ->ooseq queue that
- are now in sequence. */
- while (pcb->ooseq != NULL &&
- pcb->ooseq->tcphdr->seqno == pcb->rcv_nxt) {
-
- cseg = pcb->ooseq;
- seqno = pcb->ooseq->tcphdr->seqno;
-
- pcb->rcv_nxt += TCP_TCPLEN(cseg);
- LWIP_ASSERT("tcp_receive: ooseq tcplen > rcv_wnd\n",
- pcb->rcv_wnd >= TCP_TCPLEN(cseg));
- pcb->rcv_wnd -= TCP_TCPLEN(cseg);
-
- tcp_update_rcv_ann_wnd(pcb);
-
- if (cseg->p->tot_len > 0) {
- /* Chain this pbuf onto the pbuf that we will pass to
- the application. */
- if (recv_data) {
- pbuf_cat(recv_data, cseg->p);
- } else {
- recv_data = cseg->p;
- }
- cseg->p = NULL;
- }
- if (TCPH_FLAGS(cseg->tcphdr) & TCP_FIN) {
- LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: dequeued FIN.\n"));
- recv_flags |= TF_GOT_FIN;
- if (pcb->state == ESTABLISHED) { /* force passive close or we can move to active close */
- pcb->state = CLOSE_WAIT;
- }
- }
-
- pcb->ooseq = cseg->next;
- tcp_seg_free(cseg);
- }
-#endif /* TCP_QUEUE_OOSEQ */
-
-
- /* Acknowledge the segment(s). */
- tcp_ack(pcb);
-
- } else {
- /* We get here if the incoming segment is out-of-sequence. */
- tcp_send_empty_ack(pcb);
-#if TCP_QUEUE_OOSEQ
- /* We queue the segment on the ->ooseq queue. */
- if (pcb->ooseq == NULL) {
- pcb->ooseq = tcp_seg_copy(&inseg);
- } else {
- /* If the queue is not empty, we walk through the queue and
- try to find a place where the sequence number of the
- incoming segment is between the sequence numbers of the
- previous and the next segment on the ->ooseq queue. That is
- the place where we put the incoming segment. If needed, we
- trim the second edges of the previous and the incoming
- segment so that it will fit into the sequence.
-
- If the incoming segment has the same sequence number as a
- segment on the ->ooseq queue, we discard the segment that
- contains less data. */
-
- prev = NULL;
- for(next = pcb->ooseq; next != NULL; next = next->next) {
- if (seqno == next->tcphdr->seqno) {
- /* The sequence number of the incoming segment is the
- same as the sequence number of the segment on
- ->ooseq. We check the lengths to see which one to
- discard. */
- if (inseg.len > next->len) {
- /* The incoming segment is larger than the old
- segment. We replace some segments with the new
- one. */
- cseg = tcp_seg_copy(&inseg);
- if (cseg != NULL) {
- if (prev != NULL) {
- prev->next = cseg;
- } else {
- pcb->ooseq = cseg;
- }
- tcp_oos_insert_segment(cseg, next);
- }
- break;
- } else {
- /* Either the lenghts are the same or the incoming
- segment was smaller than the old one; in either
- case, we ditch the incoming segment. */
- break;
- }
- } else {
- if (prev == NULL) {
- if (TCP_SEQ_LT(seqno, next->tcphdr->seqno)) {
- /* The sequence number of the incoming segment is lower
- than the sequence number of the first segment on the
- queue. We put the incoming segment first on the
- queue. */
- cseg = tcp_seg_copy(&inseg);
- if (cseg != NULL) {
- pcb->ooseq = cseg;
- tcp_oos_insert_segment(cseg, next);
- }
- break;
- }
- } else {
- /*if (TCP_SEQ_LT(prev->tcphdr->seqno, seqno) &&
- TCP_SEQ_LT(seqno, next->tcphdr->seqno)) {*/
- if (TCP_SEQ_BETWEEN(seqno, prev->tcphdr->seqno+1, next->tcphdr->seqno-1)) {
- /* The sequence number of the incoming segment is in
- between the sequence numbers of the previous and
- the next segment on ->ooseq. We trim trim the previous
- segment, delete next segments that included in received segment
- and trim received, if needed. */
- cseg = tcp_seg_copy(&inseg);
- if (cseg != NULL) {
- if (TCP_SEQ_GT(prev->tcphdr->seqno + prev->len, seqno)) {
- /* We need to trim the prev segment. */
- prev->len = (u16_t)(seqno - prev->tcphdr->seqno);
- pbuf_realloc(prev->p, prev->len);
- }
- prev->next = cseg;
- tcp_oos_insert_segment(cseg, next);
- }
- break;
- }
- }
- /* If the "next" segment is the last segment on the
- ooseq queue, we add the incoming segment to the end
- of the list. */
- if (next->next == NULL &&
- TCP_SEQ_GT(seqno, next->tcphdr->seqno)) {
- if (TCPH_FLAGS(next->tcphdr) & TCP_FIN) {
- /* segment "next" already contains all data */
- break;
- }
- next->next = tcp_seg_copy(&inseg);
- if (next->next != NULL) {
- if (TCP_SEQ_GT(next->tcphdr->seqno + next->len, seqno)) {
- /* We need to trim the last segment. */
- next->len = (u16_t)(seqno - next->tcphdr->seqno);
- pbuf_realloc(next->p, next->len);
- }
- /* check if the remote side overruns our receive window */
- if ((u32_t)tcplen + seqno > pcb->rcv_nxt + (u32_t)pcb->rcv_wnd) {
- LWIP_DEBUGF(TCP_INPUT_DEBUG,
- ("tcp_receive: other end overran receive window"
- "seqno %"U32_F" len %"U16_F" right edge %"U32_F"\n",
- seqno, tcplen, pcb->rcv_nxt + pcb->rcv_wnd));
- if (TCPH_FLAGS(next->next->tcphdr) & TCP_FIN) {
- /* Must remove the FIN from the header as we're trimming
- * that byte of sequence-space from the packet */
- TCPH_FLAGS_SET(next->next->tcphdr, TCPH_FLAGS(next->next->tcphdr) &~ TCP_FIN);
- }
- /* Adjust length of segment to fit in the window. */
- next->next->len = pcb->rcv_nxt + pcb->rcv_wnd - seqno;
- pbuf_realloc(next->next->p, next->next->len);
- tcplen = TCP_TCPLEN(next->next);
- LWIP_ASSERT("tcp_receive: segment not trimmed correctly to rcv_wnd\n",
- (seqno + tcplen) == (pcb->rcv_nxt + pcb->rcv_wnd));
- }
- }
- break;
- }
- }
- prev = next;
- }
- }
-#endif /* TCP_QUEUE_OOSEQ */
-
- }
- } else {
- /* The incoming segment is not withing the window. */
- tcp_send_empty_ack(pcb);
- }
- } else {
- /* Segments with length 0 is taken care of here. Segments that
- fall out of the window are ACKed. */
- /*if (TCP_SEQ_GT(pcb->rcv_nxt, seqno) ||
- TCP_SEQ_GEQ(seqno, pcb->rcv_nxt + pcb->rcv_wnd)) {*/
- if(!TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt, pcb->rcv_nxt + pcb->rcv_wnd-1)){
- tcp_ack_now(pcb);
- }
- }
-}
-
-/**
- * Parses the options contained in the incoming segment.
- *
- * Called from tcp_listen_input() and tcp_process().
- * Currently, only the MSS option is supported!
- *
- * @param pcb the tcp_pcb for which a segment arrived
- */
-static void
-tcp_parseopt(struct tcp_pcb *pcb)
-{
- u16_t c, max_c;
- u16_t mss;
- u8_t *opts, opt;
-#if LWIP_TCP_TIMESTAMPS
- u32_t tsval;
-#endif
-
- opts = (u8_t *)tcphdr + TCP_HLEN;
-
- /* Parse the TCP MSS option, if present. */
- if(TCPH_HDRLEN(tcphdr) > 0x5) {
- max_c = (TCPH_HDRLEN(tcphdr) - 5) << 2;
- for (c = 0; c < max_c; ) {
- opt = opts[c];
- switch (opt) {
- case 0x00:
- /* End of options. */
- LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: EOL\n"));
- return;
- case 0x01:
- /* NOP option. */
- ++c;
- LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: NOP\n"));
- break;
- case 0x02:
- LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: MSS\n"));
- if (opts[c + 1] != 0x04 || c + 0x04 > max_c) {
- /* Bad length */
- LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
- return;
- }
- /* An MSS option with the right option length. */
- mss = (opts[c + 2] << 8) | opts[c + 3];
- /* Limit the mss to the configured TCP_MSS and prevent division by zero */
- pcb->mss = ((mss > TCP_MSS) || (mss == 0)) ? TCP_MSS : mss;
- /* Advance to next option */
- c += 0x04;
- break;
-#if LWIP_TCP_TIMESTAMPS
- case 0x08:
- LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: TS\n"));
- if (opts[c + 1] != 0x0A || c + 0x0A > max_c) {
- /* Bad length */
- LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
- return;
- }
- /* TCP timestamp option with valid length */
- tsval = (opts[c+2]) | (opts[c+3] << 8) |
- (opts[c+4] << 16) | (opts[c+5] << 24);
- if (flags & TCP_SYN) {
- pcb->ts_recent = ntohl(tsval);
- pcb->flags |= TF_TIMESTAMP;
- } else if (TCP_SEQ_BETWEEN(pcb->ts_lastacksent, seqno, seqno+tcplen)) {
- pcb->ts_recent = ntohl(tsval);
- }
- /* Advance to next option */
- c += 0x0A;
- break;
-#endif
- default:
- LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: other\n"));
- if (opts[c + 1] == 0) {
- LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
- /* If the length field is zero, the options are malformed
- and we don't process them further. */
- return;
- }
- /* All other options have a length field, so that we easily
- can skip past them. */
- c += opts[c + 1];
- }
- }
- }
-}
-
-#endif /* LWIP_TCP */