| /** |
| * @file |
| * |
| * Transmission Control Protocol, incoming traffic |
| * |
| * The input processing functions of TCP. |
| * |
| * 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/def.h" |
| #include "lwip/opt.h" |
| |
| #include "lwip/ip_addr.h" |
| #include "lwip/netif.h" |
| #include "lwip/mem.h" |
| #include "lwip/memp.h" |
| |
| #include "lwip/inet.h" |
| #include "lwip/tcp.h" |
| |
| #include "lwip/stats.h" |
| |
| #include "arch/perf.h" |
| #if LWIP_TCP |
| /* 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); |
| |
| |
| /* tcp_input: |
| * |
| * 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()). |
| */ |
| |
| 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); |
| |
| 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); |
| pbuf_free(p); |
| return; |
| } |
| |
| /* Don't even process incoming broadcasts/multicasts. */ |
| if (ip_addr_isbroadcast(&(iphdr->dest), inp) || |
| ip_addr_ismulticast(&(iphdr->dest))) { |
| 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); |
| |
| 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); |
| pbuf_header(p, -(hdrlen * 4)); |
| |
| /* 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; |
| |
| 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) { |
| /* Notify application that data has been received. */ |
| TCP_EVENT_RECV(pcb, recv_data, ERR_OK, err); |
| } |
| |
| /* 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); |
| } |
| } |
| } |
| |
| |
| /* We deallocate the incoming pbuf. If it was buffered by the |
| application, the application should have called pbuf_ref() to |
| increase the reference counter in the pbuf. If so, the buffer |
| isn't actually deallocated by the call to pbuf_free(), only the |
| reference count is decreased. */ |
| if (inseg.p != NULL) pbuf_free(inseg.p); |
| #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"); |
| } |
| |
| /* tcp_listen_input(): |
| * |
| * Called by tcp_input() when a segment arrives for a listening |
| * connection. |
| */ |
| |
| 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)); |
| 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; |
| } |
| /* 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); |
| |
| /* Build an MSS option. */ |
| optdata = htonl(((u32_t)2 << 24) | |
| ((u32_t)4 << 16) | |
| (((u32_t)npcb->mss / 256) << 8) | |
| (npcb->mss & 255)); |
| /* 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; |
| } |
| |
| /* tcp_timewait_input(): |
| * |
| * Called by tcp_input() when a segment arrives for a connection in |
| * TIME_WAIT. |
| */ |
| |
| 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); |
| } |
| |
| /* tcp_process |
| * |
| * 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. |
| */ |
| |
| 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_GEQ(seqno, pcb->rcv_nxt) && |
| TCP_SEQ_LEQ(seqno, pcb->rcv_nxt + pcb->rcv_wnd)) { |
| */ |
| 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; |
| } |
| } |
| |
| /* Update the PCB (in)activity timer. */ |
| pcb->tmr = tcp_ticks; |
| pcb->keep_cnt = 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; |
| pcb->cwnd = pcb->mss; |
| --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; |
| tcp_seg_free(rseg); |
| |
| /* Parse any options in the SYNACK. */ |
| tcp_parseopt(pcb); |
| |
| /* Call the user specified function to call when sucessfully |
| * connected. */ |
| TCP_EVENT_CONNECTED(pcb, ERR_OK, err); |
| tcp_ack(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)) { |
| 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; |
| } |
| /* If there was any data contained within this ACK, |
| * we'd better pass it on to the application as well. */ |
| tcp_receive(pcb); |
| pcb->cwnd = pcb->mss; |
| } |
| /* 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: |
| tcp_receive(pcb); |
| if (flags & TCP_FIN) { |
| 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)); |
| pcb->state = CLOSED; |
| recv_flags = TF_CLOSED; |
| } |
| break; |
| default: |
| break; |
| } |
| return ERR_OK; |
| } |
| |
| /* tcp_receive: |
| * |
| * 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. |
| */ |
| |
| static void |
| 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; |
| |
| |
| 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; |
| LWIP_DEBUGF(TCP_WND_DEBUG, ("tcp_receive: window update %"U32_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 currenct cwnd and the advertised window */ |
| if(pcb->cwnd > pcb->snd_wnd) |
| pcb->ssthresh = pcb->snd_wnd / 2; |
| else |
| pcb->ssthresh = pcb->cwnd / 2; |
| |
| 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_LT(pcb->lastack, ackno) && |
| TCP_SEQ_LEQ(ackno, pcb->snd_max)) { */ |
| 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. */ |
| pcb->acked = 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)); |
| 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); |
| } |
| } |
| pcb->polltmr = 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)); |
| 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)) { |
| m = 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" miliseconds)\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; |
| if (inseg.p->len < off) { |
| new_tot_len = 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; |
| } |
| pbuf_header(p, -off); |
| } else { |
| pbuf_header(inseg.p, -off); |
| } |
| /* KJM following line changed to use p->payload rather than inseg->p->payload |
| to fix bug #9076 */ |
| inseg.dataptr = p->payload; |
| inseg.len -= 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_GEQ(seqno, pcb->rcv_nxt) && |
| TCP_SEQ_LT(seqno, pcb->rcv_nxt + pcb->rcv_wnd)) {*/ |
| 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. */ |
| #if TCP_QUEUE_OOSEQ |
| if (pcb->ooseq != NULL && |
| TCP_SEQ_LEQ(pcb->ooseq->tcphdr->seqno, seqno + inseg.len)) { |
| /* We have to trim the second edge of the incoming |
| segment. */ |
| inseg.len = pcb->ooseq->tcphdr->seqno - seqno; |
| pbuf_realloc(inseg.p, inseg.len); |
| } |
| #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 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 (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; |
| } |
| |
| |
| 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; |
| } |
| } |
| 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 = 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 = 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 = 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 = seqno - next->tcphdr->seqno; |
| pbuf_realloc(next->p, next->len); |
| } |
| } |
| break; |
| } |
| } |
| prev = next; |
| } |
| } |
| #endif /* TCP_QUEUE_OOSEQ */ |
| |
| } |
| } else { |
| /*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); |
| } |
| } |
| } 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); |
| } |
| } |
| } |
| |
| /* |
| * tcp_parseopt: |
| * |
| * Parses the options contained in the incoming segment. (Code taken |
| * from uIP with only small changes.) |
| * |
| */ |
| |
| 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 */ |
| |
| |