| /** |
| * @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/priv/tcp_priv.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/ip6.h" |
| #include "lwip/ip6_addr.h" |
| #if LWIP_ND6_TCP_REACHABILITY_HINTS |
| #include "lwip/nd6.h" |
| #endif /* LWIP_ND6_TCP_REACHABILITY_HINTS */ |
| |
| /** Initial CWND calculation as defined RFC 2581 */ |
| #define LWIP_TCP_CALC_INITIAL_CWND(mss) LWIP_MIN((4U * (mss)), LWIP_MAX((2U * (mss)), 4380U)); |
| |
| /* 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 u16_t tcphdr_optlen; |
| static u16_t tcphdr_opt1len; |
| static u8_t* tcphdr_opt2; |
| static u16_t tcp_optidx; |
| static u32_t seqno, ackno; |
| static tcpwnd_size_t recv_acked; |
| static u16_t tcplen; |
| static u8_t flags; |
| |
| 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 void tcp_listen_input(struct tcp_pcb_listen *pcb); |
| static void tcp_timewait_input(struct tcp_pcb *pcb); |
| |
| static int tcp_input_delayed_close(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 TCP 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_bytes; |
| err_t err; |
| |
| LWIP_UNUSED_ARG(inp); |
| |
| PERF_START; |
| |
| TCP_STATS_INC(tcp.recv); |
| MIB2_STATS_INC(mib2.tcpinsegs); |
| |
| tcphdr = (struct tcp_hdr *)p->payload; |
| |
| #if TCP_INPUT_DEBUG |
| tcp_debug_print(tcphdr); |
| #endif |
| |
| /* Check that TCP header fits in payload */ |
| if (p->len < TCP_HLEN) { |
| /* 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); |
| goto dropped; |
| } |
| |
| /* Don't even process incoming broadcasts/multicasts. */ |
| if (ip_addr_isbroadcast(ip_current_dest_addr(), ip_current_netif()) || |
| ip_addr_ismulticast(ip_current_dest_addr())) { |
| TCP_STATS_INC(tcp.proterr); |
| goto dropped; |
| } |
| |
| #if CHECKSUM_CHECK_TCP |
| IF__NETIF_CHECKSUM_ENABLED(inp, NETIF_CHECKSUM_CHECK_TCP) { |
| /* Verify TCP checksum. */ |
| u16_t chksum = ip_chksum_pseudo(p, IP_PROTO_TCP, p->tot_len, |
| ip_current_src_addr(), ip_current_dest_addr()); |
| if (chksum != 0) { |
| LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packet discarded due to failing checksum 0x%04"X16_F"\n", |
| chksum)); |
| tcp_debug_print(tcphdr); |
| TCP_STATS_INC(tcp.chkerr); |
| goto dropped; |
| } |
| } |
| #endif /* CHECKSUM_CHECK_TCP */ |
| |
| /* sanity-check header length */ |
| hdrlen_bytes = TCPH_HDRLEN(tcphdr) * 4; |
| if ((hdrlen_bytes < TCP_HLEN) || (hdrlen_bytes > p->tot_len)) { |
| LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: invalid header length (%"U16_F")\n", (u16_t)hdrlen_bytes)); |
| TCP_STATS_INC(tcp.lenerr); |
| goto dropped; |
| } |
| |
| /* Move the payload pointer in the pbuf so that it points to the |
| TCP data instead of the TCP header. */ |
| tcphdr_optlen = hdrlen_bytes - TCP_HLEN; |
| tcphdr_opt2 = NULL; |
| if (p->len >= hdrlen_bytes) { |
| /* all options are in the first pbuf */ |
| tcphdr_opt1len = tcphdr_optlen; |
| pbuf_header(p, -(s16_t)hdrlen_bytes); /* cannot fail */ |
| } else { |
| u16_t opt2len; |
| /* TCP header fits into first pbuf, options don't - data is in the next pbuf */ |
| /* there must be a next pbuf, due to hdrlen_bytes sanity check above */ |
| LWIP_ASSERT("p->next != NULL", p->next != NULL); |
| |
| /* advance over the TCP header (cannot fail) */ |
| pbuf_header(p, -TCP_HLEN); |
| |
| /* determine how long the first and second parts of the options are */ |
| tcphdr_opt1len = p->len; |
| opt2len = tcphdr_optlen - tcphdr_opt1len; |
| |
| /* options continue in the next pbuf: set p to zero length and hide the |
| options in the next pbuf (adjusting p->tot_len) */ |
| pbuf_header(p, -(s16_t)tcphdr_opt1len); |
| |
| /* check that the options fit in the second pbuf */ |
| if (opt2len > p->next->len) { |
| /* drop short packets */ |
| LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: options overflow second pbuf (%"U16_F" bytes)\n", p->next->len)); |
| TCP_STATS_INC(tcp.lenerr); |
| goto dropped; |
| } |
| |
| /* remember the pointer to the second part of the options */ |
| tcphdr_opt2 = (u8_t*)p->next->payload; |
| |
| /* advance p->next to point after the options, and manually |
| adjust p->tot_len to keep it consistent with the changed p->next */ |
| pbuf_header(p->next, -(s16_t)opt2len); |
| p->tot_len -= opt2len; |
| |
| LWIP_ASSERT("p->len == 0", p->len == 0); |
| LWIP_ASSERT("p->tot_len == p->next->tot_len", p->tot_len == p->next->tot_len); |
| } |
| |
| /* Convert fields in TCP header to host byte order. */ |
| tcphdr->src = lwip_ntohs(tcphdr->src); |
| tcphdr->dest = lwip_ntohs(tcphdr->dest); |
| seqno = tcphdr->seqno = lwip_ntohl(tcphdr->seqno); |
| ackno = tcphdr->ackno = lwip_ntohl(tcphdr->ackno); |
| tcphdr->wnd = lwip_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, ip_current_src_addr()) && |
| ip_addr_cmp(&pcb->local_ip, ip_current_dest_addr())) { |
| /* 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; |
| } else { |
| TCP_STATS_INC(tcp.cachehit); |
| } |
| 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, ip_current_src_addr()) && |
| ip_addr_cmp(&pcb->local_ip, ip_current_dest_addr())) { |
| /* 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 (IP_IS_ANY_TYPE_VAL(lpcb->local_ip)) { |
| /* found an ANY TYPE (IPv4/IPv6) match */ |
| #if SO_REUSE |
| lpcb_any = lpcb; |
| lpcb_prev = prev; |
| #else /* SO_REUSE */ |
| break; |
| #endif /* SO_REUSE */ |
| } else if (IP_ADDR_PCB_VERSION_MATCH_EXACT(lpcb, ip_current_dest_addr())) { |
| if (ip_addr_cmp(&lpcb->local_ip, ip_current_dest_addr())) { |
| /* found an exact match */ |
| break; |
| } else if (ip_addr_isany(&lpcb->local_ip)) { |
| /* found an ANY-match */ |
| #if SO_REUSE |
| lpcb_any = lpcb; |
| lpcb_prev = prev; |
| #else /* SO_REUSE */ |
| 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; |
| } else { |
| TCP_STATS_INC(tcp.cachehit); |
| } |
| |
| 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 |
| tcp_debug_print_state(pcb->state); |
| #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; |
| recv_acked = 0; |
| |
| if (flags & TCP_PSH) { |
| p->flags |= PBUF_FLAG_PUSH; |
| } |
| |
| /* If there is data which was previously "refused" by upper layer */ |
| if (pcb->refused_data != NULL) { |
| if ((tcp_process_refused_data(pcb) == ERR_ABRT) || |
| ((pcb->refused_data != NULL) && (tcplen > 0))) { |
| /* pcb has been aborted or refused data is still refused and the new |
| segment contains data */ |
| if (pcb->rcv_ann_wnd == 0) { |
| /* this is a zero-window probe, we respond to it with current RCV.NXT |
| and drop the data segment */ |
| tcp_send_empty_ack(pcb); |
| } |
| TCP_STATS_INC(tcp.drop); |
| MIB2_STATS_INC(mib2.tcpinerrs); |
| goto aborted; |
| } |
| } |
| 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->state, pcb->errf, pcb->callback_arg, ERR_RST); |
| 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 (recv_acked > 0) { |
| u16_t acked16; |
| #if LWIP_WND_SCALE |
| /* recv_acked is u32_t but the sent callback only takes a u16_t, |
| so we might have to call it multiple times. */ |
| u32_t acked = recv_acked; |
| while (acked > 0) { |
| acked16 = (u16_t)LWIP_MIN(acked, 0xffffu); |
| acked -= acked16; |
| #else |
| { |
| acked16 = recv_acked; |
| #endif |
| TCP_EVENT_SENT(pcb, (u16_t)acked16, err); |
| if (err == ERR_ABRT) { |
| goto aborted; |
| } |
| } |
| recv_acked = 0; |
| } |
| if (tcp_input_delayed_close(pcb)) { |
| goto aborted; |
| } |
| #if TCP_QUEUE_OOSEQ && LWIP_WND_SCALE |
| while (recv_data != NULL) { |
| struct pbuf *rest = NULL; |
| pbuf_split_64k(recv_data, &rest); |
| #else /* TCP_QUEUE_OOSEQ && LWIP_WND_SCALE */ |
| if (recv_data != NULL) { |
| #endif /* TCP_QUEUE_OOSEQ && LWIP_WND_SCALE */ |
| |
| 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); |
| #if TCP_QUEUE_OOSEQ && LWIP_WND_SCALE |
| if (rest != NULL) { |
| pbuf_free(rest); |
| } |
| #endif /* TCP_QUEUE_OOSEQ && LWIP_WND_SCALE */ |
| tcp_abort(pcb); |
| goto aborted; |
| } |
| |
| /* Notify application that data has been received. */ |
| TCP_EVENT_RECV(pcb, recv_data, ERR_OK, err); |
| if (err == ERR_ABRT) { |
| #if TCP_QUEUE_OOSEQ && LWIP_WND_SCALE |
| if (rest != NULL) { |
| pbuf_free(rest); |
| } |
| #endif /* TCP_QUEUE_OOSEQ && LWIP_WND_SCALE */ |
| goto aborted; |
| } |
| |
| /* If the upper layer can't receive this data, store it */ |
| if (err != ERR_OK) { |
| #if TCP_QUEUE_OOSEQ && LWIP_WND_SCALE |
| if (rest != NULL) { |
| pbuf_cat(recv_data, rest); |
| } |
| #endif /* TCP_QUEUE_OOSEQ && LWIP_WND_SCALE */ |
| pcb->refused_data = recv_data; |
| LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: keep incoming packet, because pcb is \"full\"\n")); |
| #if TCP_QUEUE_OOSEQ && LWIP_WND_SCALE |
| break; |
| } else { |
| /* Upper layer received the data, go on with the rest if > 64K */ |
| recv_data = rest; |
| #endif /* TCP_QUEUE_OOSEQ && LWIP_WND_SCALE */ |
| } |
| } |
| |
| /* If a FIN segment was received, we call the callback |
| function with a NULL buffer to indicate EOF. */ |
| if (recv_flags & TF_GOT_FIN) { |
| if (pcb->refused_data != NULL) { |
| /* Delay this if we have refused data. */ |
| pcb->refused_data->flags |= PBUF_FLAG_TCP_FIN; |
| } else { |
| /* correct rcv_wnd as the application won't call tcp_recved() |
| for the FIN's seqno */ |
| if (pcb->rcv_wnd != TCP_WND_MAX(pcb)) { |
| pcb->rcv_wnd++; |
| } |
| TCP_EVENT_CLOSED(pcb, err); |
| if (err == ERR_ABRT) { |
| goto aborted; |
| } |
| } |
| } |
| |
| tcp_input_pcb = NULL; |
| if (tcp_input_delayed_close(pcb)) { |
| goto aborted; |
| } |
| /* 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"); |
| return; |
| dropped: |
| TCP_STATS_INC(tcp.drop); |
| MIB2_STATS_INC(mib2.tcpinerrs); |
| pbuf_free(p); |
| } |
| |
| /** Called from tcp_input to check for TF_CLOSED flag. This results in closing |
| * and deallocating a pcb at the correct place to ensure noone references it |
| * any more. |
| * @returns 1 if the pcb has been closed and deallocated, 0 otherwise |
| */ |
| static int |
| tcp_input_delayed_close(struct tcp_pcb *pcb) |
| { |
| if (recv_flags & TF_CLOSED) { |
| /* The connection has been closed and we will deallocate the |
| PCB. */ |
| if (!(pcb->flags & TF_RXCLOSED)) { |
| /* Connection closed although the application has only shut down the |
| tx side: call the PCB's err callback and indicate the closure to |
| ensure the application doesn't continue using the PCB. */ |
| TCP_EVENT_ERR(pcb->state, pcb->errf, pcb->callback_arg, ERR_CLSD); |
| } |
| tcp_pcb_remove(&tcp_active_pcbs, pcb); |
| memp_free(MEMP_TCP_PCB, pcb); |
| return 1; |
| } |
| return 0; |
| } |
| |
| /** |
| * 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 |
| * |
| * @note the segment which arrived is saved in global variables, therefore only the pcb |
| * involved is passed as a parameter to this function |
| */ |
| static void |
| tcp_listen_input(struct tcp_pcb_listen *pcb) |
| { |
| struct tcp_pcb *npcb; |
| u32_t iss; |
| err_t rc; |
| |
| if (flags & TCP_RST) { |
| /* An incoming RST should be ignored. Return. */ |
| return; |
| } |
| |
| /* 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, 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; |
| } |
| #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) { |
| err_t err; |
| LWIP_DEBUGF(TCP_DEBUG, ("tcp_listen_input: could not allocate PCB\n")); |
| TCP_STATS_INC(tcp.memerr); |
| TCP_EVENT_ACCEPT(pcb, NULL, pcb->callback_arg, ERR_MEM, err); |
| LWIP_UNUSED_ARG(err); /* err not useful here */ |
| return; |
| } |
| #if TCP_LISTEN_BACKLOG |
| pcb->accepts_pending++; |
| npcb->flags |= TF_BACKLOGPEND; |
| #endif /* TCP_LISTEN_BACKLOG */ |
| /* Set up the new PCB. */ |
| ip_addr_copy(npcb->local_ip, *ip_current_dest_addr()); |
| ip_addr_copy(npcb->remote_ip, *ip_current_src_addr()); |
| npcb->local_port = pcb->local_port; |
| npcb->remote_port = tcphdr->src; |
| npcb->state = SYN_RCVD; |
| npcb->rcv_nxt = seqno + 1; |
| npcb->rcv_ann_right_edge = npcb->rcv_nxt; |
| iss = tcp_next_iss(npcb); |
| npcb->snd_wl2 = iss; |
| npcb->snd_nxt = iss; |
| npcb->lastack = iss; |
| npcb->snd_lbb = iss; |
| npcb->snd_wl1 = seqno - 1;/* initialise to seqno-1 to force window update */ |
| npcb->callback_arg = pcb->callback_arg; |
| #if LWIP_CALLBACK_API || TCP_LISTEN_BACKLOG |
| npcb->listener = pcb; |
| #endif /* LWIP_CALLBACK_API || TCP_LISTEN_BACKLOG */ |
| /* 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_ACTIVE(npcb); |
| |
| /* Parse any options in the SYN. */ |
| tcp_parseopt(npcb); |
| npcb->snd_wnd = tcphdr->wnd; |
| npcb->snd_wnd_max = npcb->snd_wnd; |
| |
| #if TCP_CALCULATE_EFF_SEND_MSS |
| npcb->mss = tcp_eff_send_mss(npcb->mss, &npcb->local_ip, &npcb->remote_ip); |
| #endif /* TCP_CALCULATE_EFF_SEND_MSS */ |
| |
| MIB2_STATS_INC(mib2.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; |
| } |
| tcp_output(npcb); |
| } |
| return; |
| } |
| |
| /** |
| * 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 void |
| 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; |
| } |
| /* - 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; |
| } |
| } 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; |
| tcp_output(pcb); |
| } |
| return; |
| } |
| |
| /** |
| * 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) { |
| /* "In the SYN-SENT state (a RST received in response to an initial SYN), |
| the RST is acceptable if the ACK field acknowledges the SYN." */ |
| if (ackno == pcb->snd_nxt) { |
| acceptable = 1; |
| } |
| } else { |
| /* "In all states except SYN-SENT, all reset (RST) segments are validated |
| by checking their SEQ-fields." */ |
| if (seqno == pcb->rcv_nxt) { |
| acceptable = 1; |
| } else if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt, |
| pcb->rcv_nxt + pcb->rcv_wnd)) { |
| /* If the sequence number is inside the window, we only send an ACK |
| and wait for a re-send with matching sequence number. |
| This violates RFC 793, but is required to protection against |
| CVE-2004-0230 (RST spoofing attack). */ |
| tcp_ack_now(pcb); |
| } |
| } |
| |
| 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, lwip_ntohl(pcb->unacked->tcphdr->seqno))); |
| /* received SYN ACK with expected sequence number? */ |
| if ((flags & TCP_ACK) && (flags & TCP_SYN) |
| && (ackno == pcb->lastack + 1)) { |
| pcb->rcv_nxt = seqno + 1; |
| pcb->rcv_ann_right_edge = pcb->rcv_nxt; |
| pcb->lastack = ackno; |
| pcb->snd_wnd = tcphdr->wnd; |
| pcb->snd_wnd_max = pcb->snd_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->local_ip, &pcb->remote_ip); |
| #endif /* TCP_CALCULATE_EFF_SEND_MSS */ |
| |
| pcb->cwnd = LWIP_TCP_CALC_INITIAL_CWND(pcb->mss); |
| LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_process (SENT): cwnd %"TCPWNDSIZE_F |
| " ssthresh %"TCPWNDSIZE_F"\n", |
| pcb->cwnd, pcb->ssthresh)); |
| LWIP_ASSERT("pcb->snd_queuelen > 0", (pcb->snd_queuelen > 0)); |
| --pcb->snd_queuelen; |
| LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_process: SYN-SENT --queuelen %"TCPWNDSIZE_F"\n", (tcpwnd_size_t)pcb->snd_queuelen)); |
| rseg = pcb->unacked; |
| if (rseg == NULL) { |
| /* might happen if tcp_output fails in tcp_rexmit_rto() |
| in which case the segment is on the unsent list */ |
| rseg = pcb->unsent; |
| LWIP_ASSERT("no segment to free", rseg != NULL); |
| pcb->unsent = rseg->next; |
| } else { |
| pcb->unacked = rseg->next; |
| } |
| tcp_seg_free(rseg); |
| |
| /* 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; |
| } |
| |
| /* Call the user specified function to call when successfully |
| * 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); |
| /* Resend SYN immediately (don't wait for rto timeout) to establish |
| connection faster, but do not send more SYNs than we otherwise would |
| have, or we might get caught in a loop on loopback interfaces. */ |
| if (pcb->nrtx < TCP_SYNMAXRTX) { |
| pcb->rtime = 0; |
| tcp_rexmit_rto(pcb); |
| } |
| } |
| break; |
| case SYN_RCVD: |
| if (flags & TCP_ACK) { |
| /* 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 || TCP_LISTEN_BACKLOG |
| #if LWIP_CALLBACK_API |
| LWIP_ASSERT("pcb->listener->accept != NULL", |
| (pcb->listener == NULL) || (pcb->listener->accept != NULL)); |
| #endif |
| if (pcb->listener == NULL) { |
| /* listen pcb might be closed by now */ |
| err = ERR_VAL; |
| } else |
| #endif /* LWIP_CALLBACK_API || TCP_LISTEN_BACKLOG */ |
| { |
| tcp_backlog_accepted(pcb); |
| /* Call the accept function. */ |
| TCP_EVENT_ACCEPT(pcb->listener, pcb, pcb->callback_arg, 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; |
| } |
| /* 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 (recv_acked != 0) { |
| recv_acked--; |
| } |
| |
| pcb->cwnd = LWIP_TCP_CALC_INITIAL_CWND(pcb->mss); |
| LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_process (SYN_RCVD): cwnd %"TCPWNDSIZE_F |
| " ssthresh %"TCPWNDSIZE_F"\n", |
| pcb->cwnd, pcb->ssthresh)); |
| |
| 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) && |
| pcb->unsent == NULL) { |
| 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_ACTIVE(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->unsent == NULL) { |
| 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_ACTIVE(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 && pcb->unsent == NULL) { |
| 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_ACTIVE(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 && pcb->unsent == NULL) { |
| 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, it 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 |
| * 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 */ |
| s32_t off; |
| s16_t m; |
| u32_t right_wnd_edge; |
| u16_t new_tot_len; |
| int found_dupack = 0; |
| #if TCP_OOSEQ_MAX_BYTES || TCP_OOSEQ_MAX_PBUFS |
| u32_t ooseq_blen; |
| u16_t ooseq_qlen; |
| #endif /* TCP_OOSEQ_MAX_BYTES || TCP_OOSEQ_MAX_PBUFS */ |
| |
| LWIP_ASSERT("tcp_receive: wrong state", pcb->state >= ESTABLISHED); |
| |
| 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 && (u32_t)SND_WND_SCALE(pcb, tcphdr->wnd) > pcb->snd_wnd)) { |
| pcb->snd_wnd = SND_WND_SCALE(pcb, tcphdr->wnd); |
| /* keep track of the biggest window announced by the remote host to calculate |
| the maximum segment size */ |
| if (pcb->snd_wnd_max < pcb->snd_wnd) { |
| pcb->snd_wnd_max = pcb->snd_wnd; |
| } |
| pcb->snd_wl1 = seqno; |
| pcb->snd_wl2 = ackno; |
| if (pcb->snd_wnd == 0) { |
| if (pcb->persist_backoff == 0) { |
| /* start persist timer */ |
| pcb->persist_cnt = 0; |
| pcb->persist_backoff = 1; |
| } |
| } else if (pcb->persist_backoff > 0) { |
| /* stop persist timer */ |
| pcb->persist_backoff = 0; |
| } |
| LWIP_DEBUGF(TCP_WND_DEBUG, ("tcp_receive: window update %"TCPWNDSIZE_F"\n", pcb->snd_wnd)); |
| #if TCP_WND_DEBUG |
| } else { |
| if (pcb->snd_wnd != (tcpwnd_size_t)SND_WND_SCALE(pcb, 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)) { |
| /* 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 ((u8_t)(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 ((tcpwnd_size_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; |
| |
| /* 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 ((tcpwnd_size_t)(pcb->cwnd + pcb->mss) > pcb->cwnd) { |
| pcb->cwnd += pcb->mss; |
| } |
| LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_receive: slow start cwnd %"TCPWNDSIZE_F"\n", pcb->cwnd)); |
| } else { |
| tcpwnd_size_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 %"TCPWNDSIZE_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? |
| lwip_ntohl(pcb->unacked->tcphdr->seqno): 0, |
| pcb->unacked != NULL? |
| lwip_ntohl(pcb->unacked->tcphdr->seqno) + TCP_TCPLEN(pcb->unacked): 0)); |
| |
| /* Remove segment from the unacknowledged list if the incoming |
| ACK acknowledges them. */ |
| while (pcb->unacked != NULL && |
| TCP_SEQ_LEQ(lwip_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", |
| lwip_ntohl(pcb->unacked->tcphdr->seqno), |
| lwip_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 %"TCPWNDSIZE_F" ... ", (tcpwnd_size_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); |
| recv_acked += next->len; |
| tcp_seg_free(next); |
| |
| LWIP_DEBUGF(TCP_QLEN_DEBUG, ("%"TCPWNDSIZE_F" (after freeing unacked)\n", (tcpwnd_size_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; |
| |
| #if LWIP_IPV6 && LWIP_ND6_TCP_REACHABILITY_HINTS |
| if (ip_current_is_v6()) { |
| /* Inform neighbor reachability of forward progress. */ |
| nd6_reachability_hint(ip6_current_src_addr()); |
| } |
| #endif /* LWIP_IPV6 && LWIP_ND6_TCP_REACHABILITY_HINTS*/ |
| } else { |
| /* Out of sequence ACK, didn't really ack anything */ |
| tcp_send_empty_ack(pcb); |
| } |
| |
| /* 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, lwip_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", |
| lwip_ntohl(pcb->unsent->tcphdr->seqno), lwip_ntohl(pcb->unsent->tcphdr->seqno) + |
| TCP_TCPLEN(pcb->unsent))); |
| |
| next = pcb->unsent; |
| pcb->unsent = pcb->unsent->next; |
| #if TCP_OVERSIZE |
| if (pcb->unsent == NULL) { |
| pcb->unsent_oversize = 0; |
| } |
| #endif /* TCP_OVERSIZE */ |
| LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_receive: queuelen %"TCPWNDSIZE_F" ... ", (tcpwnd_size_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 */ |
| pcb->snd_queuelen -= pbuf_clen(next->p); |
| recv_acked += next->len; |
| tcp_seg_free(next); |
| LWIP_DEBUGF(TCP_QLEN_DEBUG, ("%"TCPWNDSIZE_F" (after freeing unsent)\n", (tcpwnd_size_t)pcb->snd_queuelen)); |
| if (pcb->snd_queuelen != 0) { |
| LWIP_ASSERT("tcp_receive: valid queue length", |
| pcb->unacked != NULL || pcb->unsent != NULL); |
| } |
| } |
| pcb->snd_buf += recv_acked; |
| /* 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, (u16_t)(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, (u16_t)(pcb->rto * TCP_SLOW_INTERVAL))); |
| |
| pcb->rttest = 0; |
| } |
| } |
| |
| /* If the incoming segment contains data, we must process it |
| further unless the pcb already received a FIN. |
| (RFC 793, chapter 3.9, "SEGMENT ARRIVES" in states CLOSE-WAIT, CLOSING, |
| LAST-ACK and TIME-WAIT: "Ignore the segment text.") */ |
| if ((tcplen > 0) && (pcb->state < CLOSE_WAIT)) { |
| /* 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.*/ |
| |
| struct pbuf *p = inseg.p; |
| off = pcb->rcv_nxt - seqno; |
| 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) & ~(unsigned int)TCP_FIN); |
| } |
| /* Adjust length of segment to fit in the window. */ |
| TCPWND_CHECK16(pcb->rcv_wnd); |
| inseg.len = (u16_t)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) != 0 && |
| (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. */ |
| /* With window scaling, this can overflow recv_data->tot_len, but |
| that's not a problem since we explicitly fix that before passing |
| recv_data 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); |
| |
| #if LWIP_IPV6 && LWIP_ND6_TCP_REACHABILITY_HINTS |
| if (ip_current_is_v6()) { |
| /* Inform neighbor reachability of forward progress. */ |
| nd6_reachability_hint(ip6_current_src_addr()); |
| } |
| #endif /* LWIP_IPV6 && LWIP_ND6_TCP_REACHABILITY_HINTS*/ |
| |
| } 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 lengths 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 (TCP_SEQ_GT((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 = (u16_t)(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; |
| } |
| } |
| #if TCP_OOSEQ_MAX_BYTES || TCP_OOSEQ_MAX_PBUFS |
| /* Check that the data on ooseq doesn't exceed one of the limits |
| and throw away everything above that limit. */ |
| ooseq_blen = 0; |
| ooseq_qlen = 0; |
| prev = NULL; |
| for (next = pcb->ooseq; next != NULL; prev = next, next = next->next) { |
| struct pbuf *p = next->p; |
| ooseq_blen += p->tot_len; |
| ooseq_qlen += pbuf_clen(p); |
| if ((ooseq_blen > TCP_OOSEQ_MAX_BYTES) || |
| (ooseq_qlen > TCP_OOSEQ_MAX_PBUFS)) { |
| /* too much ooseq data, dump this and everything after it */ |
| tcp_segs_free(next); |
| if (prev == NULL) { |
| /* first ooseq segment is too much, dump the whole queue */ |
| pcb->ooseq = NULL; |
| } else { |
| /* just dump 'next' and everything after it */ |
| prev->next = NULL; |
| } |
| break; |
| } |
| } |
| #endif /* TCP_OOSEQ_MAX_BYTES || TCP_OOSEQ_MAX_PBUFS */ |
| #endif /* TCP_QUEUE_OOSEQ */ |
| } |
| } else { |
| /* The incoming segment is not within 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_BETWEEN(seqno, pcb->rcv_nxt, pcb->rcv_nxt + pcb->rcv_wnd - 1)) { |
| tcp_ack_now(pcb); |
| } |
| } |
| } |
| |
| static u8_t |
| tcp_getoptbyte(void) |
| { |
| if ((tcphdr_opt2 == NULL) || (tcp_optidx < tcphdr_opt1len)) { |
| u8_t* opts = (u8_t *)tcphdr + TCP_HLEN; |
| return opts[tcp_optidx++]; |
| } else { |
| u8_t idx = (u8_t)(tcp_optidx++ - tcphdr_opt1len); |
| return tcphdr_opt2[idx]; |
| } |
| } |
| |
| /** |
| * 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) |
| { |
| u8_t data; |
| u16_t mss; |
| #if LWIP_TCP_TIMESTAMPS |
| u32_t tsval; |
| #endif |
| |
| /* Parse the TCP MSS option, if present. */ |
| if (tcphdr_optlen != 0) { |
| for (tcp_optidx = 0; tcp_optidx < tcphdr_optlen; ) { |
| u8_t opt = tcp_getoptbyte(); |
| switch (opt) { |
| case LWIP_TCP_OPT_EOL: |
| /* End of options. */ |
| LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: EOL\n")); |
| return; |
| case LWIP_TCP_OPT_NOP: |
| /* NOP option. */ |
| LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: NOP\n")); |
| break; |
| case LWIP_TCP_OPT_MSS: |
| LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: MSS\n")); |
| if (tcp_getoptbyte() != LWIP_TCP_OPT_LEN_MSS || (tcp_optidx - 2 + LWIP_TCP_OPT_LEN_MSS) > tcphdr_optlen) { |
| /* Bad length */ |
| LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n")); |
| return; |
| } |
| /* An MSS option with the right option length. */ |
| mss = (tcp_getoptbyte() << 8); |
| mss |= tcp_getoptbyte(); |
| /* Limit the mss to the configured TCP_MSS and prevent division by zero */ |
| pcb->mss = ((mss > TCP_MSS) || (mss == 0)) ? TCP_MSS : mss; |
| break; |
| #if LWIP_WND_SCALE |
| case LWIP_TCP_OPT_WS: |
| LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: WND_SCALE\n")); |
| if (tcp_getoptbyte() != LWIP_TCP_OPT_LEN_WS || (tcp_optidx - 2 + LWIP_TCP_OPT_LEN_WS) > tcphdr_optlen) { |
| /* Bad length */ |
| LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n")); |
| return; |
| } |
| /* An WND_SCALE option with the right option length. */ |
| data = tcp_getoptbyte(); |
| /* If syn was received with wnd scale option, |
| activate wnd scale opt, but only if this is not a retransmission */ |
| if ((flags & TCP_SYN) && !(pcb->flags & TF_WND_SCALE)) { |
| pcb->snd_scale = data; |
| if (pcb->snd_scale > 14U) { |
| pcb->snd_scale = 14U; |
| } |
| pcb->rcv_scale = TCP_RCV_SCALE; |
| pcb->flags |= TF_WND_SCALE; |
| /* window scaling is enabled, we can use the full receive window */ |
| LWIP_ASSERT("window not at default value", pcb->rcv_wnd == TCPWND_MIN16(TCP_WND)); |
| LWIP_ASSERT("window not at default value", pcb->rcv_ann_wnd == TCPWND_MIN16(TCP_WND)); |
| pcb->rcv_wnd = pcb->rcv_ann_wnd = TCP_WND; |
| } |
| break; |
| #endif |
| #if LWIP_TCP_TIMESTAMPS |
| case LWIP_TCP_OPT_TS: |
| LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: TS\n")); |
| if (tcp_getoptbyte() != LWIP_TCP_OPT_LEN_TS || (tcp_optidx - 2 + LWIP_TCP_OPT_LEN_TS) > tcphdr_optlen) { |
| /* Bad length */ |
| LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n")); |
| return; |
| } |
| /* TCP timestamp option with valid length */ |
| tsval = tcp_getoptbyte(); |
| tsval |= (tcp_getoptbyte() << 8); |
| tsval |= (tcp_getoptbyte() << 16); |
| tsval |= (tcp_getoptbyte() << 24); |
| if (flags & TCP_SYN) { |
| pcb->ts_recent = lwip_ntohl(tsval); |
| /* Enable sending timestamps in every segment now that we know |
| the remote host supports it. */ |
| pcb->flags |= TF_TIMESTAMP; |
| } else if (TCP_SEQ_BETWEEN(pcb->ts_lastacksent, seqno, seqno+tcplen)) { |
| pcb->ts_recent = lwip_ntohl(tsval); |
| } |
| /* Advance to next option (6 bytes already read) */ |
| tcp_optidx += LWIP_TCP_OPT_LEN_TS - 6; |
| break; |
| #endif |
| default: |
| LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: other\n")); |
| data = tcp_getoptbyte(); |
| if (data < 2) { |
| 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. */ |
| tcp_optidx += data - 2; |
| } |
| } |
| } |
| } |
| |
| void |
| tcp_trigger_input_pcb_close(void) |
| { |
| recv_flags |= TF_CLOSED; |
| } |
| |
| #endif /* LWIP_TCP */ |
