/** | |
* @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.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.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 u8_t 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; | |
u8_t hdrlen; | |
err_t err; | |
PERF_START; | |
TCP_STATS_INC(tcp.recv); | |
snmp_inc_tcpinsegs(); | |
iphdr = 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(&(iphdr->dest), inp) || | |
ip_addr_ismulticast(&(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, (struct ip_addr *)&(iphdr->src), | |
(struct ip_addr *)&(iphdr->dest), | |
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, (struct ip_addr *)&(iphdr->src), (struct ip_addr *)&(iphdr->dest), | |
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) & TCP_FLAGS; | |
tcplen = p->tot_len + ((flags & TCP_FIN || flags & 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), &(iphdr->src)) && | |
ip_addr_cmp(&(pcb->local_ip), &(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), &(iphdr->src)) && | |
ip_addr_cmp(&(pcb->local_ip), &(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 ((ip_addr_isany(&(lpcb->local_ip)) || | |
ip_addr_cmp(&(lpcb->local_ip), &(iphdr->dest))) && | |
lpcb->local_port == tcphdr->dest) { | |
/* 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; | |
} | |
prev = (struct tcp_pcb *)lpcb; | |
} | |
} | |
#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 { | |
/* 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); | |
tcp_input_pcb = NULL; | |
/* 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 (recv_data != NULL) { | |
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 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) { | |
TCP_EVENT_RECV(pcb, NULL, ERR_OK, err); | |
} | |
/* If there were no errors, we try to send something out. */ | |
if (err == ERR_OK) { | |
tcp_output(pcb); | |
} | |
} | |
} | |
/* give up our reference to inseg.p */ | |
if (inseg.p != NULL) | |
{ | |
pbuf_free(inseg.p); | |
inseg.p = NULL; | |
} | |
#if TCP_INPUT_DEBUG | |
#if TCP_DEBUG | |
tcp_debug_print_state(pcb->state); | |
#endif /* TCP_DEBUG */ | |
#endif /* TCP_INPUT_DEBUG */ | |
} 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, | |
&(iphdr->dest), &(iphdr->src), | |
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; | |
u32_t optdata; | |
/* 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, | |
&(iphdr->dest), &(iphdr->src), | |
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) { | |
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_set(&(npcb->local_ip), &(iphdr->dest)); | |
npcb->local_port = pcb->local_port; | |
ip_addr_set(&(npcb->remote_ip), &(iphdr->src)); | |
npcb->remote_port = tcphdr->src; | |
npcb->state = SYN_RCVD; | |
npcb->rcv_nxt = seqno + 1; | |
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_DEBUG|SOF_DONTROUTE|SOF_KEEPALIVE|SOF_OOBINLINE|SOF_LINGER); | |
/* 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(); | |
/* Build an MSS option. */ | |
optdata = TCP_BUILD_MSS_OPTION(); | |
/* Send a SYN|ACK together with the MSS option. */ | |
tcp_enqueue(npcb, NULL, 0, TCP_SYN | TCP_ACK, 0, (u8_t *)&optdata, 4); | |
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) | |
{ | |
if (TCP_SEQ_GT(seqno + tcplen, pcb->rcv_nxt)) { | |
pcb->rcv_nxt = seqno + tcplen; | |
} | |
if (tcplen > 0) { | |
tcp_ack_now(pcb); | |
} | |
return tcp_output(pcb); | |
} | |
/** | |
* 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; | |
u8_t accepted_inseq; | |
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_ann_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; | |
} | |
} | |
/* Update the PCB (in)activity timer. */ | |
pcb->tmr = tcp_ticks; | |
pcb->keep_cnt_sent = 0; | |
/* 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->lastack = ackno; | |
pcb->snd_wnd = tcphdr->wnd; | |
pcb->snd_wl1 = seqno - 1; /* initialise to seqno - 1 to force window update */ | |
pcb->state = ESTABLISHED; | |
/* Parse any options in the SYNACK before using pcb->mss since that | |
* can be changed by the received options! */ | |
tcp_parseopt(pcb); | |
#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); | |
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, &(iphdr->dest), &(iphdr->src), | |
tcphdr->dest, tcphdr->src); | |
} | |
break; | |
case SYN_RCVD: | |
if (flags & TCP_ACK && | |
!(flags & TCP_RST)) { | |
/* 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. */ | |
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. */ | |
accepted_inseq = tcp_receive(pcb); | |
pcb->cwnd = ((old_cwnd == 1) ? (pcb->mss * 2) : pcb->mss); | |
if ((flags & TCP_FIN) && accepted_inseq) { | |
tcp_ack_now(pcb); | |
pcb->state = CLOSE_WAIT; | |
} | |
} | |
/* incorrect ACK number */ | |
else { | |
/* send RST */ | |
tcp_rst(ackno, seqno + tcplen, &(iphdr->dest), &(iphdr->src), | |
tcphdr->dest, tcphdr->src); | |
} | |
} | |
break; | |
case CLOSE_WAIT: | |
/* FALLTHROUGH */ | |
case ESTABLISHED: | |
accepted_inseq = tcp_receive(pcb); | |
if ((flags & TCP_FIN) && accepted_inseq) { /* passive close */ | |
tcp_ack_now(pcb); | |
pcb->state = CLOSE_WAIT; | |
} | |
break; | |
case FIN_WAIT_1: | |
tcp_receive(pcb); | |
if (flags & TCP_FIN) { | |
if (flags & TCP_ACK && ackno == pcb->snd_nxt) { | |
LWIP_DEBUGF(TCP_DEBUG, | |
("TCP connection closed %"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 (flags & TCP_FIN) { | |
LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed %"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 %"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 LAST_ACK: | |
tcp_receive(pcb); | |
if (flags & TCP_ACK && ackno == pcb->snd_nxt) { | |
LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed %"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; | |
} | |
/** | |
* 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(). | |
* | |
* @return 1 if the incoming segment is the next in sequence, 0 if not | |
*/ | |
static u8_t | |
tcp_receive(struct tcp_pcb *pcb) | |
{ | |
struct tcp_seg *next; | |
#if TCP_QUEUE_OOSEQ | |
struct tcp_seg *prev, *cseg; | |
#endif | |
struct pbuf *p; | |
s32_t off; | |
s16_t m; | |
u32_t right_wnd_edge; | |
u16_t new_tot_len; | |
u8_t accepted_inseq = 0; | |
if (flags & TCP_ACK) { | |
right_wnd_edge = pcb->snd_wnd + pcb->snd_wl1; | |
/* 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" snd_max %"U32_F" ackno %"U32_F" wl1 %"U32_F" seqno %"U32_F" wl2 %"U32_F"\n", | |
pcb->lastack, pcb->snd_max, ackno, pcb->snd_wl1, seqno, pcb->snd_wl2)); | |
} | |
#endif /* TCP_WND_DEBUG */ | |
} | |
if (pcb->lastack == ackno) { | |
pcb->acked = 0; | |
if (pcb->snd_wl1 + pcb->snd_wnd == right_wnd_edge){ | |
++pcb->dupacks; | |
if (pcb->dupacks >= 3 && pcb->unacked != NULL) { | |
if (!(pcb->flags & TF_INFR)) { | |
/* This is fast retransmit. Retransmit the first unacked segment. */ | |
LWIP_DEBUGF(TCP_FR_DEBUG, ("tcp_receive: dupacks %"U16_F" (%"U32_F"), fast retransmit %"U32_F"\n", | |
(u16_t)pcb->dupacks, pcb->lastack, | |
ntohl(pcb->unacked->tcphdr->seqno))); | |
tcp_rexmit(pcb); | |
/* Set ssthresh to max (FlightSize / 2, 2*SMSS) */ | |
/*pcb->ssthresh = LWIP_MAX((pcb->snd_max - | |
pcb->lastack) / 2, | |
2 * pcb->mss);*/ | |
/* Set ssthresh to half of the minimum of the current cwnd and the advertised window */ | |
if (pcb->cwnd > pcb->snd_wnd) | |
pcb->ssthresh = pcb->snd_wnd / 2; | |
else | |
pcb->ssthresh = pcb->cwnd / 2; | |
/* The minimum value for ssthresh should be 2 MSS */ | |
if (pcb->ssthresh < 2*pcb->mss) { | |
LWIP_DEBUGF(TCP_FR_DEBUG, ("tcp_receive: The minimum value for ssthresh %"U16_F" should be min 2 mss %"U16_F"...\n", pcb->ssthresh, 2*pcb->mss)); | |
pcb->ssthresh = 2*pcb->mss; | |
} | |
pcb->cwnd = pcb->ssthresh + 3 * pcb->mss; | |
pcb->flags |= TF_INFR; | |
} else { | |
/* 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 { | |
LWIP_DEBUGF(TCP_FR_DEBUG, ("tcp_receive: dupack averted %"U32_F" %"U32_F"\n", | |
pcb->snd_wl1 + pcb->snd_wnd, right_wnd_edge)); | |
} | |
} else if (TCP_SEQ_BETWEEN(ackno, pcb->lastack+1, pcb->snd_max)){ | |
/* 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))); | |
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_LEQ(ntohl(pcb->unsent->tcphdr->seqno) + TCP_TCPLEN(pcb->unsent), ackno) && | |
TCP_SEQ_LEQ(ackno, pcb->snd_max)*/ | |
TCP_SEQ_BETWEEN(ackno, ntohl(pcb->unsent->tcphdr->seqno) + TCP_TCPLEN(pcb->unsent), pcb->snd_max) | |
) { | |
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))); | |
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); | |
} | |
if (pcb->unsent != NULL) { | |
pcb->snd_nxt = htonl(pcb->unsent->tcphdr->seqno); | |
} | |
} | |
/* 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_ann_wnd - 1)){ | |
if (pcb->rcv_nxt == seqno) { | |
accepted_inseq = 1; | |
/* 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. */ | |
#if TCP_QUEUE_OOSEQ | |
if (pcb->ooseq != NULL && | |
TCP_SEQ_LEQ(pcb->ooseq->tcphdr->seqno, seqno + inseg.len)) { | |
if (pcb->ooseq->len > 0) { | |
/* We have to trim the second edge of the incoming | |
segment. */ | |
inseg.len = (u16_t)(pcb->ooseq->tcphdr->seqno - seqno); | |
pbuf_realloc(inseg.p, inseg.len); | |
} else { | |
/* does the ooseq segment contain only flags that are in inseg also? */ | |
if ((TCPH_FLAGS(inseg.tcphdr) & (TCP_FIN|TCP_SYN)) == | |
(TCPH_FLAGS(pcb->ooseq->tcphdr) & (TCP_FIN|TCP_SYN))) { | |
struct tcp_seg *old_ooseq = pcb->ooseq; | |
pcb->ooseq = pcb->ooseq->next; | |
memp_free(MEMP_TCP_SEG, old_ooseq); | |
} | |
} | |
} | |
#endif /* TCP_QUEUE_OOSEQ */ | |
tcplen = TCP_TCPLEN(&inseg); | |
/* First received FIN will be ACKed +1, on any successive (duplicate) | |
* FINs we are already in CLOSE_WAIT and have already done +1. | |
*/ | |
if (pcb->state != CLOSE_WAIT) { | |
pcb->rcv_nxt += tcplen; | |
} | |
/* Update the receiver's (our) window. */ | |
if (pcb->rcv_wnd < tcplen) { | |
pcb->rcv_wnd = 0; | |
} else { | |
pcb->rcv_wnd -= tcplen; | |
} | |
if (pcb->rcv_ann_wnd < tcplen) { | |
pcb->rcv_ann_wnd = 0; | |
} else { | |
pcb->rcv_ann_wnd -= tcplen; | |
} | |
/* 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 | |
is 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); | |
if (pcb->rcv_wnd < TCP_TCPLEN(cseg)) { | |
pcb->rcv_wnd = 0; | |
} else { | |
pcb->rcv_wnd -= TCP_TCPLEN(cseg); | |
} | |
if (pcb->rcv_ann_wnd < TCP_TCPLEN(cseg)) { | |
pcb->rcv_ann_wnd = 0; | |
} else { | |
pcb->rcv_ann_wnd -= TCP_TCPLEN(cseg); | |
} | |
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_ack_now(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 the old segment with the new | |
one. */ | |
cseg = tcp_seg_copy(&inseg); | |
if (cseg != NULL) { | |
cseg->next = next->next; | |
if (prev != NULL) { | |
prev->next = cseg; | |
} else { | |
pcb->ooseq = cseg; | |
} | |
} | |
tcp_seg_free(next); | |
if (cseg->next != NULL) { | |
next = cseg->next; | |
if (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); | |
} | |
} | |
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. */ | |
if (TCP_SEQ_GT(seqno + inseg.len, next->tcphdr->seqno)) { | |
/* We need to trim the incoming segment. */ | |
inseg.len = (u16_t)(next->tcphdr->seqno - seqno); | |
pbuf_realloc(inseg.p, inseg.len); | |
} | |
cseg = tcp_seg_copy(&inseg); | |
if (cseg != NULL) { | |
cseg->next = next; | |
pcb->ooseq = cseg; | |
} | |
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 and insert the | |
incoming segment and trim the previous segment, if | |
needed. */ | |
if (TCP_SEQ_GT(seqno + inseg.len, next->tcphdr->seqno)) { | |
/* We need to trim the incoming segment. */ | |
inseg.len = (u16_t)(next->tcphdr->seqno - seqno); | |
pbuf_realloc(inseg.p, inseg.len); | |
} | |
cseg = tcp_seg_copy(&inseg); | |
if (cseg != NULL) { | |
cseg->next = next; | |
prev->next = cseg; | |
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); | |
} | |
} | |
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)) { | |
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); | |
} | |
} | |
break; | |
} | |
} | |
prev = next; | |
} | |
} | |
#endif /* TCP_QUEUE_OOSEQ */ | |
} | |
} else { | |
if(!TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt, | |
pcb->rcv_nxt + pcb->rcv_ann_wnd-1)){ | |
tcp_ack_now(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); | |
} | |
} | |
return accepted_inseq; | |
} | |
/** | |
* Parses the options contained in the incoming segment. (Code taken | |
* from uIP with only small changes.) | |
* | |
* 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) | |
{ | |
u8_t c; | |
u8_t *opts, opt; | |
u16_t mss; | |
opts = (u8_t *)tcphdr + TCP_HLEN; | |
/* Parse the TCP MSS option, if present. */ | |
if(TCPH_HDRLEN(tcphdr) > 0x5) { | |
for(c = 0; c < (TCPH_HDRLEN(tcphdr) - 5) << 2 ;) { | |
opt = opts[c]; | |
if (opt == 0x00) { | |
/* End of options. */ | |
break; | |
} else if (opt == 0x01) { | |
++c; | |
/* NOP option. */ | |
} else if (opt == 0x02 && | |
opts[c + 1] == 0x04) { | |
/* An MSS option with the right option length. */ | |
mss = (opts[c + 2] << 8) | opts[c + 3]; | |
pcb->mss = mss > TCP_MSS? TCP_MSS: mss; | |
/* And we are done processing options. */ | |
break; | |
} else { | |
if (opts[c + 1] == 0) { | |
/* If the length field is zero, the options are malformed | |
and we don't process them further. */ | |
break; | |
} | |
/* All other options have a length field, so that we easily | |
can skip past them. */ | |
c += opts[c + 1]; | |
} | |
} | |
} | |
} | |
#endif /* LWIP_TCP */ |