diff options
Diffstat (limited to 'core/lwip/src/core/tcp_in.c')
| -rw-r--r-- | core/lwip/src/core/tcp_in.c | 1567 |
1 files changed, 1567 insertions, 0 deletions
diff --git a/core/lwip/src/core/tcp_in.c b/core/lwip/src/core/tcp_in.c new file mode 100644 index 00000000..90952648 --- /dev/null +++ b/core/lwip/src/core/tcp_in.c @@ -0,0 +1,1567 @@ +/** + * @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.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) || (tcplen > 0)) { + /* if err == ERR_ABRT, 'pcb' is already deallocated */ + /* Drop incoming packets because pcb is "full" (only if the incoming + segment contains data). */ + 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) { + LWIP_ASSERT("pcb->refused_data == NULL", pcb->refused_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); + } + } + 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 */ |