| /** |
| * @file |
| * Transmission Control Protocol, outgoing traffic |
| * |
| * The output functions of TCP. |
| * |
| */ |
| |
| /* |
| * Copyright (c) 2001-2004 Swedish Institute of Computer Science. |
| * All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without modification, |
| * are permitted provided that the following conditions are met: |
| * |
| * 1. Redistributions of source code must retain the above copyright notice, |
| * this list of conditions and the following disclaimer. |
| * 2. Redistributions in binary form must reproduce the above copyright notice, |
| * this list of conditions and the following disclaimer in the documentation |
| * and/or other materials provided with the distribution. |
| * 3. The name of the author may not be used to endorse or promote products |
| * derived from this software without specific prior written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED |
| * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF |
| * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT |
| * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, |
| * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT |
| * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
| * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
| * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING |
| * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY |
| * OF SUCH DAMAGE. |
| * |
| * This file is part of the lwIP TCP/IP stack. |
| * |
| * Author: Adam Dunkels <adam@sics.se> |
| * |
| */ |
| |
| #include "lwip/opt.h" |
| |
| #if LWIP_TCP /* don't build if not configured for use in lwipopts.h */ |
| |
| #include "lwip/tcp.h" |
| #include "lwip/def.h" |
| #include "lwip/mem.h" |
| #include "lwip/memp.h" |
| #include "lwip/sys.h" |
| #include "lwip/ip_addr.h" |
| #include "lwip/netif.h" |
| #include "lwip/inet.h" |
| #include "lwip/inet_chksum.h" |
| #include "lwip/stats.h" |
| #include "lwip/snmp.h" |
| |
| #include <string.h> |
| |
| /* Forward declarations.*/ |
| static void tcp_output_segment(struct tcp_seg *seg, struct tcp_pcb *pcb); |
| |
| static struct tcp_hdr * |
| tcp_output_set_header(struct tcp_pcb *pcb, struct pbuf *p, int optlen, |
| u32_t seqno_be /* already in network byte order */) |
| { |
| struct tcp_hdr *tcphdr = p->payload; |
| tcphdr->src = htons(pcb->local_port); |
| tcphdr->dest = htons(pcb->remote_port); |
| tcphdr->seqno = seqno_be; |
| tcphdr->ackno = htonl(pcb->rcv_nxt); |
| TCPH_FLAGS_SET(tcphdr, TCP_ACK); |
| tcphdr->wnd = htons(pcb->rcv_ann_wnd); |
| tcphdr->urgp = 0; |
| TCPH_HDRLEN_SET(tcphdr, (5 + optlen / 4)); |
| tcphdr->chksum = 0; |
| |
| /* If we're sending a packet, update the announced right window edge */ |
| pcb->rcv_ann_right_edge = pcb->rcv_nxt + pcb->rcv_ann_wnd; |
| |
| return tcphdr; |
| } |
| |
| /** |
| * Called by tcp_close() to send a segment including flags but not data. |
| * |
| * @param pcb the tcp_pcb over which to send a segment |
| * @param flags the flags to set in the segment header |
| * @return ERR_OK if sent, another err_t otherwise |
| */ |
| err_t |
| tcp_send_ctrl(struct tcp_pcb *pcb, u8_t flags) |
| { |
| /* no data, no length, flags, copy=1, no optdata */ |
| return tcp_enqueue(pcb, NULL, 0, flags, TCP_WRITE_FLAG_COPY, 0); |
| } |
| |
| /** |
| * Write data for sending (but does not send it immediately). |
| * |
| * It waits in the expectation of more data being sent soon (as |
| * it can send them more efficiently by combining them together). |
| * To prompt the system to send data now, call tcp_output() after |
| * calling tcp_write(). |
| * |
| * @param pcb Protocol control block of the TCP connection to enqueue data for. |
| * @param data pointer to the data to send |
| * @param len length (in bytes) of the data to send |
| * @param apiflags combination of following flags : |
| * - TCP_WRITE_FLAG_COPY (0x01) data will be copied into memory belonging to the stack |
| * - TCP_WRITE_FLAG_MORE (0x02) for TCP connection, PSH flag will be set on last segment sent, |
| * @return ERR_OK if enqueued, another err_t on error |
| * |
| * @see tcp_write() |
| */ |
| err_t |
| tcp_write(struct tcp_pcb *pcb, const void *data, u16_t len, u8_t apiflags) |
| { |
| LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_write(pcb=%p, data=%p, len=%"U16_F", apiflags=%"U16_F")\n", (void *)pcb, |
| data, len, (u16_t)apiflags)); |
| /* connection is in valid state for data transmission? */ |
| if (pcb->state == ESTABLISHED || |
| pcb->state == CLOSE_WAIT || |
| pcb->state == SYN_SENT || |
| pcb->state == SYN_RCVD) { |
| if (len > 0) { |
| #if LWIP_TCP_TIMESTAMPS |
| return tcp_enqueue(pcb, (void *)data, len, 0, apiflags, |
| pcb->flags & TF_TIMESTAMP ? TF_SEG_OPTS_TS : 0); |
| #else |
| return tcp_enqueue(pcb, (void *)data, len, 0, apiflags, 0); |
| #endif |
| } |
| return ERR_OK; |
| } else { |
| LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_STATE | LWIP_DBG_LEVEL_SEVERE, ("tcp_write() called in invalid state\n")); |
| return ERR_CONN; |
| } |
| } |
| |
| /** |
| * Enqueue data and/or TCP options for transmission |
| * |
| * Called by tcp_connect(), tcp_listen_input(), tcp_send_ctrl() and tcp_write(). |
| * |
| * @param pcb Protocol control block for the TCP connection to enqueue data for. |
| * @param arg Pointer to the data to be enqueued for sending. |
| * @param len Data length in bytes |
| * @param flags tcp header flags to set in the outgoing segment |
| * @param apiflags combination of following flags : |
| * - TCP_WRITE_FLAG_COPY (0x01) data will be copied into memory belonging to the stack |
| * - TCP_WRITE_FLAG_MORE (0x02) for TCP connection, PSH flag will be set on last segment sent, |
| * @param optflags options to include in segment later on (see definition of struct tcp_seg) |
| */ |
| err_t |
| tcp_enqueue(struct tcp_pcb *pcb, void *arg, u16_t len, |
| u8_t flags, u8_t apiflags, u8_t optflags) |
| { |
| struct pbuf *p; |
| struct tcp_seg *seg, *useg, *queue; |
| u32_t seqno; |
| u16_t left, seglen; |
| void *ptr; |
| u16_t queuelen; |
| u8_t optlen; |
| |
| LWIP_DEBUGF(TCP_OUTPUT_DEBUG, |
| ("tcp_enqueue(pcb=%p, arg=%p, len=%"U16_F", flags=%"X16_F", apiflags=%"U16_F")\n", |
| (void *)pcb, arg, len, (u16_t)flags, (u16_t)apiflags)); |
| LWIP_ERROR("tcp_enqueue: packet needs payload, options, or SYN/FIN (programmer violates API)", |
| ((len != 0) || (optflags != 0) || ((flags & (TCP_SYN | TCP_FIN)) != 0)), |
| return ERR_ARG;); |
| LWIP_ERROR("tcp_enqueue: len != 0 || arg == NULL (programmer violates API)", |
| ((len != 0) || (arg == NULL)), return ERR_ARG;); |
| |
| /* fail on too much data */ |
| if (len > pcb->snd_buf) { |
| LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_LEVEL_WARNING, |
| ("tcp_enqueue: too much data (len=%"U16_F" > snd_buf=%"U16_F")\n", len, pcb->snd_buf)); |
| pcb->flags |= TF_NAGLEMEMERR; |
| return ERR_MEM; |
| } |
| left = len; |
| ptr = arg; |
| |
| optlen = LWIP_TCP_OPT_LENGTH(optflags); |
| |
| /* seqno will be the sequence number of the first segment enqueued |
| * by the call to this function. */ |
| seqno = pcb->snd_lbb; |
| |
| LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_enqueue: queuelen: %"U16_F"\n", (u16_t)pcb->snd_queuelen)); |
| |
| /* If total number of pbufs on the unsent/unacked queues exceeds the |
| * configured maximum, return an error */ |
| queuelen = pcb->snd_queuelen; |
| /* check for configured max queuelen and possible overflow */ |
| if ((queuelen >= TCP_SND_QUEUELEN) || (queuelen > TCP_SNDQUEUELEN_OVERFLOW)) { |
| LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_LEVEL_WARNING, |
| ("tcp_enqueue: too long queue %"U16_F" (max %"U16_F")\n", queuelen, TCP_SND_QUEUELEN)); |
| TCP_STATS_INC(tcp.memerr); |
| pcb->flags |= TF_NAGLEMEMERR; |
| return ERR_MEM; |
| } |
| if (queuelen != 0) { |
| LWIP_ASSERT("tcp_enqueue: pbufs on queue => at least one queue non-empty", |
| pcb->unacked != NULL || pcb->unsent != NULL); |
| } else { |
| LWIP_ASSERT("tcp_enqueue: no pbufs on queue => both queues empty", |
| pcb->unacked == NULL && pcb->unsent == NULL); |
| } |
| |
| /* First, break up the data into segments and tuck them together in |
| * the local "queue" variable. */ |
| useg = queue = seg = NULL; |
| seglen = 0; |
| while (queue == NULL || left > 0) { |
| /* The segment length (including options) should be at most the MSS */ |
| seglen = left > (pcb->mss - optlen) ? (pcb->mss - optlen) : left; |
| |
| /* Allocate memory for tcp_seg, and fill in fields. */ |
| seg = memp_malloc(MEMP_TCP_SEG); |
| if (seg == NULL) { |
| LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_LEVEL_SERIOUS, |
| ("tcp_enqueue: could not allocate memory for tcp_seg\n")); |
| goto memerr; |
| } |
| seg->next = NULL; |
| seg->p = NULL; |
| |
| /* first segment of to-be-queued data? */ |
| if (queue == NULL) { |
| queue = seg; |
| } |
| /* subsequent segments of to-be-queued data */ |
| else { |
| /* Attach the segment to the end of the queued segments */ |
| LWIP_ASSERT("useg != NULL", useg != NULL); |
| useg->next = seg; |
| } |
| /* remember last segment of to-be-queued data for next iteration */ |
| useg = seg; |
| |
| /* If copy is set, memory should be allocated |
| * and data copied into pbuf, otherwise data comes from |
| * ROM or other static memory, and need not be copied. */ |
| if (apiflags & TCP_WRITE_FLAG_COPY) { |
| if ((seg->p = pbuf_alloc(PBUF_TRANSPORT, seglen + optlen, PBUF_RAM)) == NULL) { |
| LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_LEVEL_SERIOUS, |
| ("tcp_enqueue : could not allocate memory for pbuf copy size %"U16_F"\n", seglen)); |
| goto memerr; |
| } |
| LWIP_ASSERT("check that first pbuf can hold the complete seglen", |
| (seg->p->len >= seglen + optlen)); |
| queuelen += pbuf_clen(seg->p); |
| if (arg != NULL) { |
| MEMCPY((char *)seg->p->payload + optlen, ptr, seglen); |
| } |
| seg->dataptr = seg->p->payload; |
| } |
| /* do not copy data */ |
| else { |
| /* First, allocate a pbuf for the headers. */ |
| if ((seg->p = pbuf_alloc(PBUF_TRANSPORT, optlen, PBUF_RAM)) == NULL) { |
| LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_LEVEL_SERIOUS, |
| ("tcp_enqueue: could not allocate memory for header pbuf\n")); |
| goto memerr; |
| } |
| queuelen += pbuf_clen(seg->p); |
| |
| /* Second, allocate a pbuf for holding the data. |
| * since the referenced data is available at least until it is sent out on the |
| * link (as it has to be ACKed by the remote party) we can safely use PBUF_ROM |
| * instead of PBUF_REF here. |
| */ |
| if (left > 0) { |
| if ((p = pbuf_alloc(PBUF_RAW, seglen, PBUF_ROM)) == NULL) { |
| /* If allocation fails, we have to deallocate the header pbuf as well. */ |
| pbuf_free(seg->p); |
| seg->p = NULL; |
| LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_LEVEL_SERIOUS, |
| ("tcp_enqueue: could not allocate memory for zero-copy pbuf\n")); |
| goto memerr; |
| } |
| ++queuelen; |
| /* reference the non-volatile payload data */ |
| p->payload = ptr; |
| seg->dataptr = ptr; |
| |
| /* Concatenate the headers and data pbufs together. */ |
| pbuf_cat(seg->p/*header*/, p/*data*/); |
| p = NULL; |
| } |
| } |
| |
| /* Now that there are more segments queued, we check again if the |
| length of the queue exceeds the configured maximum or overflows. */ |
| if ((queuelen > TCP_SND_QUEUELEN) || (queuelen > TCP_SNDQUEUELEN_OVERFLOW)) { |
| LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_LEVEL_SERIOUS, |
| ("tcp_enqueue: queue too long %"U16_F" (%"U16_F")\n", queuelen, TCP_SND_QUEUELEN)); |
| goto memerr; |
| } |
| |
| seg->len = seglen; |
| |
| /* build TCP header */ |
| if (pbuf_header(seg->p, TCP_HLEN)) { |
| LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("tcp_enqueue: no room for TCP header in pbuf.\n")); |
| TCP_STATS_INC(tcp.err); |
| goto memerr; |
| } |
| seg->tcphdr = seg->p->payload; |
| seg->tcphdr->src = htons(pcb->local_port); |
| seg->tcphdr->dest = htons(pcb->remote_port); |
| seg->tcphdr->seqno = htonl(seqno); |
| seg->tcphdr->urgp = 0; |
| TCPH_FLAGS_SET(seg->tcphdr, flags); |
| /* don't fill in tcphdr->ackno and tcphdr->wnd until later */ |
| |
| seg->flags = optflags; |
| |
| /* Set the length of the header */ |
| TCPH_HDRLEN_SET(seg->tcphdr, (5 + optlen / 4)); |
| LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_TRACE, ("tcp_enqueue: queueing %"U32_F":%"U32_F" (0x%"X16_F")\n", |
| ntohl(seg->tcphdr->seqno), |
| ntohl(seg->tcphdr->seqno) + TCP_TCPLEN(seg), |
| (u16_t)flags)); |
| |
| left -= seglen; |
| seqno += seglen; |
| ptr = (void *)((u8_t *)ptr + seglen); |
| } |
| |
| /* Now that the data to be enqueued has been broken up into TCP |
| segments in the queue variable, we add them to the end of the |
| pcb->unsent queue. */ |
| if (pcb->unsent == NULL) { |
| useg = NULL; |
| } |
| else { |
| for (useg = pcb->unsent; useg->next != NULL; useg = useg->next); |
| } |
| /* { useg is last segment on the unsent queue, NULL if list is empty } */ |
| |
| /* If there is room in the last pbuf on the unsent queue, |
| chain the first pbuf on the queue together with that. */ |
| if (useg != NULL && |
| TCP_TCPLEN(useg) != 0 && |
| !(TCPH_FLAGS(useg->tcphdr) & (TCP_SYN | TCP_FIN)) && |
| (!(flags & (TCP_SYN | TCP_FIN)) || (flags == TCP_FIN)) && |
| /* fit within max seg size */ |
| (useg->len + queue->len <= pcb->mss) && |
| /* only concatenate segments with the same options */ |
| (useg->flags == queue->flags) && |
| /* segments are consecutive */ |
| (ntohl(useg->tcphdr->seqno) + useg->len == ntohl(queue->tcphdr->seqno)) ) { |
| /* Remove TCP header from first segment of our to-be-queued list */ |
| if(pbuf_header(queue->p, -(TCP_HLEN + optlen))) { |
| /* Can we cope with this failing? Just assert for now */ |
| LWIP_ASSERT("pbuf_header failed\n", 0); |
| TCP_STATS_INC(tcp.err); |
| goto memerr; |
| } |
| if (queue->p->len == 0) { |
| /* free the first (header-only) pbuf if it is now empty (contained only headers) */ |
| struct pbuf *old_q = queue->p; |
| queue->p = queue->p->next; |
| old_q->next = NULL; |
| queuelen--; |
| pbuf_free(old_q); |
| } |
| if (flags & TCP_FIN) { |
| /* the new segment contains only FIN, no data -> put the FIN into the last segment */ |
| LWIP_ASSERT("FIN enqueued together with data", queue->p == NULL && queue->len == 0); |
| TCPH_SET_FLAG(useg->tcphdr, TCP_FIN); |
| } else { |
| LWIP_ASSERT("zero-length pbuf", (queue->p != NULL) && (queue->p->len > 0)); |
| pbuf_cat(useg->p, queue->p); |
| useg->len += queue->len; |
| useg->next = queue->next; |
| } |
| |
| LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("tcp_enqueue: chaining segments, new len %"U16_F"\n", useg->len)); |
| if (seg == queue) { |
| seg = useg; |
| seglen = useg->len; |
| } |
| memp_free(MEMP_TCP_SEG, queue); |
| } |
| else { |
| /* empty list */ |
| if (useg == NULL) { |
| /* initialize list with this segment */ |
| pcb->unsent = queue; |
| } |
| /* enqueue segment */ |
| else { |
| useg->next = queue; |
| } |
| } |
| if ((flags & TCP_SYN) || (flags & TCP_FIN)) { |
| ++len; |
| } |
| if (flags & TCP_FIN) { |
| pcb->flags |= TF_FIN; |
| } |
| pcb->snd_lbb += len; |
| |
| pcb->snd_buf -= len; |
| |
| /* update number of segments on the queues */ |
| pcb->snd_queuelen = queuelen; |
| LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_enqueue: %"S16_F" (after enqueued)\n", pcb->snd_queuelen)); |
| if (pcb->snd_queuelen != 0) { |
| LWIP_ASSERT("tcp_enqueue: valid queue length", |
| pcb->unacked != NULL || pcb->unsent != NULL); |
| } |
| |
| /* Set the PSH flag in the last segment that we enqueued, but only |
| if the segment has data (indicated by seglen > 0). */ |
| if (seg != NULL && seglen > 0 && seg->tcphdr != NULL && ((apiflags & TCP_WRITE_FLAG_MORE)==0)) { |
| TCPH_SET_FLAG(seg->tcphdr, TCP_PSH); |
| } |
| |
| return ERR_OK; |
| memerr: |
| pcb->flags |= TF_NAGLEMEMERR; |
| TCP_STATS_INC(tcp.memerr); |
| |
| if (queue != NULL) { |
| tcp_segs_free(queue); |
| } |
| if (pcb->snd_queuelen != 0) { |
| LWIP_ASSERT("tcp_enqueue: valid queue length", pcb->unacked != NULL || |
| pcb->unsent != NULL); |
| } |
| LWIP_DEBUGF(TCP_QLEN_DEBUG | LWIP_DBG_STATE, ("tcp_enqueue: %"S16_F" (with mem err)\n", pcb->snd_queuelen)); |
| return ERR_MEM; |
| } |
| |
| |
| #if LWIP_TCP_TIMESTAMPS |
| /* Build a timestamp option (12 bytes long) at the specified options pointer) |
| * |
| * @param pcb tcp_pcb |
| * @param opts option pointer where to store the timestamp option |
| */ |
| static void |
| tcp_build_timestamp_option(struct tcp_pcb *pcb, u32_t *opts) |
| { |
| /* Pad with two NOP options to make everything nicely aligned */ |
| opts[0] = htonl(0x0101080A); |
| opts[1] = htonl(sys_now()); |
| opts[2] = htonl(pcb->ts_recent); |
| } |
| #endif |
| |
| /** Send an ACK without data. |
| * |
| * @param pcb Protocol control block for the TCP connection to send the ACK |
| */ |
| err_t |
| tcp_send_empty_ack(struct tcp_pcb *pcb) |
| { |
| struct pbuf *p; |
| struct tcp_hdr *tcphdr; |
| u8_t optlen = 0; |
| |
| #if LWIP_TCP_TIMESTAMPS |
| if (pcb->flags & TF_TIMESTAMP) { |
| optlen = LWIP_TCP_OPT_LENGTH(TF_SEG_OPTS_TS); |
| } |
| #endif |
| p = pbuf_alloc(PBUF_IP, TCP_HLEN + optlen, PBUF_RAM); |
| if (p == NULL) { |
| LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output: (ACK) could not allocate pbuf\n")); |
| return ERR_BUF; |
| } |
| LWIP_DEBUGF(TCP_OUTPUT_DEBUG, |
| ("tcp_output: sending ACK for %"U32_F"\n", pcb->rcv_nxt)); |
| /* remove ACK flags from the PCB, as we send an empty ACK now */ |
| pcb->flags &= ~(TF_ACK_DELAY | TF_ACK_NOW); |
| |
| tcphdr = tcp_output_set_header(pcb, p, optlen, htonl(pcb->snd_nxt)); |
| |
| /* NB. MSS option is only sent on SYNs, so ignore it here */ |
| #if LWIP_TCP_TIMESTAMPS |
| pcb->ts_lastacksent = pcb->rcv_nxt; |
| |
| if (pcb->flags & TF_TIMESTAMP) { |
| tcp_build_timestamp_option(pcb, (u32_t *)(tcphdr + 1)); |
| } |
| #endif |
| |
| #if CHECKSUM_GEN_TCP |
| tcphdr->chksum = inet_chksum_pseudo(p, &(pcb->local_ip), &(pcb->remote_ip), |
| IP_PROTO_TCP, p->tot_len); |
| #endif |
| #if LWIP_NETIF_HWADDRHINT |
| ip_output_hinted(p, &(pcb->local_ip), &(pcb->remote_ip), pcb->ttl, pcb->tos, |
| IP_PROTO_TCP, &(pcb->addr_hint)); |
| #else /* LWIP_NETIF_HWADDRHINT*/ |
| ip_output(p, &(pcb->local_ip), &(pcb->remote_ip), pcb->ttl, pcb->tos, |
| IP_PROTO_TCP); |
| #endif /* LWIP_NETIF_HWADDRHINT*/ |
| pbuf_free(p); |
| |
| return ERR_OK; |
| } |
| |
| /** |
| * Find out what we can send and send it |
| * |
| * @param pcb Protocol control block for the TCP connection to send data |
| * @return ERR_OK if data has been sent or nothing to send |
| * another err_t on error |
| */ |
| err_t |
| tcp_output(struct tcp_pcb *pcb) |
| { |
| struct tcp_seg *seg, *useg; |
| u32_t wnd, snd_nxt; |
| #if TCP_CWND_DEBUG |
| s16_t i = 0; |
| #endif /* TCP_CWND_DEBUG */ |
| |
| /* First, check if we are invoked by the TCP input processing |
| code. If so, we do not output anything. Instead, we rely on the |
| input processing code to call us when input processing is done |
| with. */ |
| if (tcp_input_pcb == pcb) { |
| return ERR_OK; |
| } |
| |
| wnd = LWIP_MIN(pcb->snd_wnd, pcb->cwnd); |
| |
| seg = pcb->unsent; |
| |
| /* If the TF_ACK_NOW flag is set and no data will be sent (either |
| * because the ->unsent queue is empty or because the window does |
| * not allow it), construct an empty ACK segment and send it. |
| * |
| * If data is to be sent, we will just piggyback the ACK (see below). |
| */ |
| if (pcb->flags & TF_ACK_NOW && |
| (seg == NULL || |
| ntohl(seg->tcphdr->seqno) - pcb->lastack + seg->len > wnd)) { |
| return tcp_send_empty_ack(pcb); |
| } |
| |
| /* useg should point to last segment on unacked queue */ |
| useg = pcb->unacked; |
| if (useg != NULL) { |
| for (; useg->next != NULL; useg = useg->next); |
| } |
| |
| #if TCP_OUTPUT_DEBUG |
| if (seg == NULL) { |
| LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output: nothing to send (%p)\n", |
| (void*)pcb->unsent)); |
| } |
| #endif /* TCP_OUTPUT_DEBUG */ |
| #if TCP_CWND_DEBUG |
| if (seg == NULL) { |
| LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_output: snd_wnd %"U16_F |
| ", cwnd %"U16_F", wnd %"U32_F |
| ", seg == NULL, ack %"U32_F"\n", |
| pcb->snd_wnd, pcb->cwnd, wnd, pcb->lastack)); |
| } else { |
| LWIP_DEBUGF(TCP_CWND_DEBUG, |
| ("tcp_output: snd_wnd %"U16_F", cwnd %"U16_F", wnd %"U32_F |
| ", effwnd %"U32_F", seq %"U32_F", ack %"U32_F"\n", |
| pcb->snd_wnd, pcb->cwnd, wnd, |
| ntohl(seg->tcphdr->seqno) - pcb->lastack + seg->len, |
| ntohl(seg->tcphdr->seqno), pcb->lastack)); |
| } |
| #endif /* TCP_CWND_DEBUG */ |
| /* data available and window allows it to be sent? */ |
| while (seg != NULL && |
| ntohl(seg->tcphdr->seqno) - pcb->lastack + seg->len <= wnd) { |
| LWIP_ASSERT("RST not expected here!", |
| (TCPH_FLAGS(seg->tcphdr) & TCP_RST) == 0); |
| /* Stop sending if the nagle algorithm would prevent it |
| * Don't stop: |
| * - if tcp_enqueue had a memory error before (prevent delayed ACK timeout) or |
| * - if FIN was already enqueued for this PCB (SYN is always alone in a segment - |
| * either seg->next != NULL or pcb->unacked == NULL; |
| * RST is no sent using tcp_enqueue/tcp_output. |
| */ |
| if((tcp_do_output_nagle(pcb) == 0) && |
| ((pcb->flags & (TF_NAGLEMEMERR | TF_FIN)) == 0)){ |
| break; |
| } |
| #if TCP_CWND_DEBUG |
| LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_output: snd_wnd %"U16_F", cwnd %"U16_F", wnd %"U32_F", effwnd %"U32_F", seq %"U32_F", ack %"U32_F", i %"S16_F"\n", |
| pcb->snd_wnd, pcb->cwnd, wnd, |
| ntohl(seg->tcphdr->seqno) + seg->len - |
| pcb->lastack, |
| ntohl(seg->tcphdr->seqno), pcb->lastack, i)); |
| ++i; |
| #endif /* TCP_CWND_DEBUG */ |
| |
| pcb->unsent = seg->next; |
| |
| if (pcb->state != SYN_SENT) { |
| TCPH_SET_FLAG(seg->tcphdr, TCP_ACK); |
| pcb->flags &= ~(TF_ACK_DELAY | TF_ACK_NOW); |
| } |
| |
| tcp_output_segment(seg, pcb); |
| snd_nxt = ntohl(seg->tcphdr->seqno) + TCP_TCPLEN(seg); |
| if (TCP_SEQ_LT(pcb->snd_nxt, snd_nxt)) { |
| pcb->snd_nxt = snd_nxt; |
| } |
| /* put segment on unacknowledged list if length > 0 */ |
| if (TCP_TCPLEN(seg) > 0) { |
| seg->next = NULL; |
| /* unacked list is empty? */ |
| if (pcb->unacked == NULL) { |
| pcb->unacked = seg; |
| useg = seg; |
| /* unacked list is not empty? */ |
| } else { |
| /* In the case of fast retransmit, the packet should not go to the tail |
| * of the unacked queue, but rather somewhere before it. We need to check for |
| * this case. -STJ Jul 27, 2004 */ |
| if (TCP_SEQ_LT(ntohl(seg->tcphdr->seqno), ntohl(useg->tcphdr->seqno))){ |
| /* add segment to before tail of unacked list, keeping the list sorted */ |
| struct tcp_seg **cur_seg = &(pcb->unacked); |
| while (*cur_seg && |
| TCP_SEQ_LT(ntohl((*cur_seg)->tcphdr->seqno), ntohl(seg->tcphdr->seqno))) { |
| cur_seg = &((*cur_seg)->next ); |
| } |
| seg->next = (*cur_seg); |
| (*cur_seg) = seg; |
| } else { |
| /* add segment to tail of unacked list */ |
| useg->next = seg; |
| useg = useg->next; |
| } |
| } |
| /* do not queue empty segments on the unacked list */ |
| } else { |
| tcp_seg_free(seg); |
| } |
| seg = pcb->unsent; |
| } |
| |
| if (seg != NULL && pcb->persist_backoff == 0 && |
| ntohl(seg->tcphdr->seqno) - pcb->lastack + seg->len > pcb->snd_wnd) { |
| /* prepare for persist timer */ |
| pcb->persist_cnt = 0; |
| pcb->persist_backoff = 1; |
| } |
| |
| pcb->flags &= ~TF_NAGLEMEMERR; |
| return ERR_OK; |
| } |
| |
| /** |
| * Called by tcp_output() to actually send a TCP segment over IP. |
| * |
| * @param seg the tcp_seg to send |
| * @param pcb the tcp_pcb for the TCP connection used to send the segment |
| */ |
| static void |
| tcp_output_segment(struct tcp_seg *seg, struct tcp_pcb *pcb) |
| { |
| u16_t len; |
| struct netif *netif; |
| u32_t *opts; |
| |
| /** @bug Exclude retransmitted segments from this count. */ |
| snmp_inc_tcpoutsegs(); |
| |
| /* The TCP header has already been constructed, but the ackno and |
| wnd fields remain. */ |
| seg->tcphdr->ackno = htonl(pcb->rcv_nxt); |
| |
| /* advertise our receive window size in this TCP segment */ |
| seg->tcphdr->wnd = htons(pcb->rcv_ann_wnd); |
| |
| pcb->rcv_ann_right_edge = pcb->rcv_nxt + pcb->rcv_ann_wnd; |
| |
| /* Add any requested options. NB MSS option is only set on SYN |
| packets, so ignore it here */ |
| opts = (u32_t *)(seg->tcphdr + 1); |
| if (seg->flags & TF_SEG_OPTS_MSS) { |
| TCP_BUILD_MSS_OPTION(*opts); |
| opts += 1; |
| } |
| #if LWIP_TCP_TIMESTAMPS |
| pcb->ts_lastacksent = pcb->rcv_nxt; |
| |
| if (seg->flags & TF_SEG_OPTS_TS) { |
| tcp_build_timestamp_option(pcb, opts); |
| opts += 3; |
| } |
| #endif |
| |
| /* If we don't have a local IP address, we get one by |
| calling ip_route(). */ |
| if (ip_addr_isany(&(pcb->local_ip))) { |
| netif = ip_route(&(pcb->remote_ip)); |
| if (netif == NULL) { |
| return; |
| } |
| ip_addr_set(&(pcb->local_ip), &(netif->ip_addr)); |
| } |
| |
| /* Set retransmission timer running if it is not currently enabled */ |
| if(pcb->rtime == -1) |
| pcb->rtime = 0; |
| |
| if (pcb->rttest == 0) { |
| pcb->rttest = tcp_ticks; |
| pcb->rtseq = ntohl(seg->tcphdr->seqno); |
| |
| LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_output_segment: rtseq %"U32_F"\n", pcb->rtseq)); |
| } |
| LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output_segment: %"U32_F":%"U32_F"\n", |
| htonl(seg->tcphdr->seqno), htonl(seg->tcphdr->seqno) + |
| seg->len)); |
| |
| len = (u16_t)((u8_t *)seg->tcphdr - (u8_t *)seg->p->payload); |
| |
| seg->p->len -= len; |
| seg->p->tot_len -= len; |
| |
| seg->p->payload = seg->tcphdr; |
| |
| seg->tcphdr->chksum = 0; |
| #if CHECKSUM_GEN_TCP |
| seg->tcphdr->chksum = inet_chksum_pseudo(seg->p, |
| &(pcb->local_ip), |
| &(pcb->remote_ip), |
| IP_PROTO_TCP, seg->p->tot_len); |
| #endif |
| TCP_STATS_INC(tcp.xmit); |
| |
| #if LWIP_NETIF_HWADDRHINT |
| ip_output_hinted(seg->p, &(pcb->local_ip), &(pcb->remote_ip), pcb->ttl, pcb->tos, |
| IP_PROTO_TCP, &(pcb->addr_hint)); |
| #else /* LWIP_NETIF_HWADDRHINT*/ |
| ip_output(seg->p, &(pcb->local_ip), &(pcb->remote_ip), pcb->ttl, pcb->tos, |
| IP_PROTO_TCP); |
| #endif /* LWIP_NETIF_HWADDRHINT*/ |
| } |
| |
| /** |
| * Send a TCP RESET packet (empty segment with RST flag set) either to |
| * abort a connection or to show that there is no matching local connection |
| * for a received segment. |
| * |
| * Called by tcp_abort() (to abort a local connection), tcp_input() (if no |
| * matching local pcb was found), tcp_listen_input() (if incoming segment |
| * has ACK flag set) and tcp_process() (received segment in the wrong state) |
| * |
| * Since a RST segment is in most cases not sent for an active connection, |
| * tcp_rst() has a number of arguments that are taken from a tcp_pcb for |
| * most other segment output functions. |
| * |
| * @param seqno the sequence number to use for the outgoing segment |
| * @param ackno the acknowledge number to use for the outgoing segment |
| * @param local_ip the local IP address to send the segment from |
| * @param remote_ip the remote IP address to send the segment to |
| * @param local_port the local TCP port to send the segment from |
| * @param remote_port the remote TCP port to send the segment to |
| */ |
| void |
| tcp_rst(u32_t seqno, u32_t ackno, |
| struct ip_addr *local_ip, struct ip_addr *remote_ip, |
| u16_t local_port, u16_t remote_port) |
| { |
| struct pbuf *p; |
| struct tcp_hdr *tcphdr; |
| p = pbuf_alloc(PBUF_IP, TCP_HLEN, PBUF_RAM); |
| if (p == NULL) { |
| LWIP_DEBUGF(TCP_DEBUG, ("tcp_rst: could not allocate memory for pbuf\n")); |
| return; |
| } |
| LWIP_ASSERT("check that first pbuf can hold struct tcp_hdr", |
| (p->len >= sizeof(struct tcp_hdr))); |
| |
| tcphdr = p->payload; |
| tcphdr->src = htons(local_port); |
| tcphdr->dest = htons(remote_port); |
| tcphdr->seqno = htonl(seqno); |
| tcphdr->ackno = htonl(ackno); |
| TCPH_FLAGS_SET(tcphdr, TCP_RST | TCP_ACK); |
| tcphdr->wnd = htons(TCP_WND); |
| tcphdr->urgp = 0; |
| TCPH_HDRLEN_SET(tcphdr, 5); |
| |
| tcphdr->chksum = 0; |
| #if CHECKSUM_GEN_TCP |
| tcphdr->chksum = inet_chksum_pseudo(p, local_ip, remote_ip, |
| IP_PROTO_TCP, p->tot_len); |
| #endif |
| TCP_STATS_INC(tcp.xmit); |
| snmp_inc_tcpoutrsts(); |
| /* Send output with hardcoded TTL since we have no access to the pcb */ |
| ip_output(p, local_ip, remote_ip, TCP_TTL, 0, IP_PROTO_TCP); |
| pbuf_free(p); |
| LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_rst: seqno %"U32_F" ackno %"U32_F".\n", seqno, ackno)); |
| } |
| |
| /** |
| * Requeue all unacked segments for retransmission |
| * |
| * Called by tcp_slowtmr() for slow retransmission. |
| * |
| * @param pcb the tcp_pcb for which to re-enqueue all unacked segments |
| */ |
| void |
| tcp_rexmit_rto(struct tcp_pcb *pcb) |
| { |
| struct tcp_seg *seg; |
| |
| if (pcb->unacked == NULL) { |
| return; |
| } |
| |
| /* Move all unacked segments to the head of the unsent queue */ |
| for (seg = pcb->unacked; seg->next != NULL; seg = seg->next); |
| /* concatenate unsent queue after unacked queue */ |
| seg->next = pcb->unsent; |
| /* unsent queue is the concatenated queue (of unacked, unsent) */ |
| pcb->unsent = pcb->unacked; |
| /* unacked queue is now empty */ |
| pcb->unacked = NULL; |
| |
| /* increment number of retransmissions */ |
| ++pcb->nrtx; |
| |
| /* Don't take any RTT measurements after retransmitting. */ |
| pcb->rttest = 0; |
| |
| /* Do the actual retransmission */ |
| tcp_output(pcb); |
| } |
| |
| /** |
| * Requeue the first unacked segment for retransmission |
| * |
| * Called by tcp_receive() for fast retramsmit. |
| * |
| * @param pcb the tcp_pcb for which to retransmit the first unacked segment |
| */ |
| void |
| tcp_rexmit(struct tcp_pcb *pcb) |
| { |
| struct tcp_seg *seg; |
| struct tcp_seg **cur_seg; |
| |
| if (pcb->unacked == NULL) { |
| return; |
| } |
| |
| /* Move the first unacked segment to the unsent queue */ |
| /* Keep the unsent queue sorted. */ |
| seg = pcb->unacked; |
| pcb->unacked = seg->next; |
| |
| cur_seg = &(pcb->unsent); |
| while (*cur_seg && |
| TCP_SEQ_LT(ntohl((*cur_seg)->tcphdr->seqno), ntohl(seg->tcphdr->seqno))) { |
| cur_seg = &((*cur_seg)->next ); |
| } |
| seg->next = *cur_seg; |
| *cur_seg = seg; |
| |
| ++pcb->nrtx; |
| |
| /* Don't take any rtt measurements after retransmitting. */ |
| pcb->rttest = 0; |
| |
| /* Do the actual retransmission. */ |
| snmp_inc_tcpretranssegs(); |
| /* No need to call tcp_output: we are always called from tcp_input() |
| and thus tcp_output directly returns. */ |
| } |
| |
| |
| /** |
| * Handle retransmission after three dupacks received |
| * |
| * @param pcb the tcp_pcb for which to retransmit the first unacked segment |
| */ |
| void |
| tcp_rexmit_fast(struct tcp_pcb *pcb) |
| { |
| if (pcb->unacked != NULL && !(pcb->flags & TF_INFR)) { |
| /* This is fast retransmit. Retransmit the first unacked segment. */ |
| LWIP_DEBUGF(TCP_FR_DEBUG, |
| ("tcp_receive: dupacks %"U16_F" (%"U32_F |
| "), fast retransmit %"U32_F"\n", |
| (u16_t)pcb->dupacks, pcb->lastack, |
| ntohl(pcb->unacked->tcphdr->seqno))); |
| tcp_rexmit(pcb); |
| |
| /* Set ssthresh to half of the minimum of the current |
| * cwnd and the advertised window */ |
| if (pcb->cwnd > pcb->snd_wnd) |
| pcb->ssthresh = pcb->snd_wnd / 2; |
| else |
| pcb->ssthresh = pcb->cwnd / 2; |
| |
| /* The minimum value for ssthresh should be 2 MSS */ |
| if (pcb->ssthresh < 2*pcb->mss) { |
| LWIP_DEBUGF(TCP_FR_DEBUG, |
| ("tcp_receive: The minimum value for ssthresh %"U16_F |
| " should be min 2 mss %"U16_F"...\n", |
| pcb->ssthresh, 2*pcb->mss)); |
| pcb->ssthresh = 2*pcb->mss; |
| } |
| |
| pcb->cwnd = pcb->ssthresh + 3 * pcb->mss; |
| pcb->flags |= TF_INFR; |
| } |
| } |
| |
| |
| /** |
| * Send keepalive packets to keep a connection active although |
| * no data is sent over it. |
| * |
| * Called by tcp_slowtmr() |
| * |
| * @param pcb the tcp_pcb for which to send a keepalive packet |
| */ |
| void |
| tcp_keepalive(struct tcp_pcb *pcb) |
| { |
| struct pbuf *p; |
| struct tcp_hdr *tcphdr; |
| |
| LWIP_DEBUGF(TCP_DEBUG, ("tcp_keepalive: sending KEEPALIVE probe to %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n", |
| ip4_addr1(&pcb->remote_ip), ip4_addr2(&pcb->remote_ip), |
| ip4_addr3(&pcb->remote_ip), ip4_addr4(&pcb->remote_ip))); |
| |
| LWIP_DEBUGF(TCP_DEBUG, ("tcp_keepalive: tcp_ticks %"U32_F" pcb->tmr %"U32_F" pcb->keep_cnt_sent %"U16_F"\n", |
| tcp_ticks, pcb->tmr, pcb->keep_cnt_sent)); |
| |
| p = pbuf_alloc(PBUF_IP, TCP_HLEN, PBUF_RAM); |
| |
| if(p == NULL) { |
| LWIP_DEBUGF(TCP_DEBUG, |
| ("tcp_keepalive: could not allocate memory for pbuf\n")); |
| return; |
| } |
| LWIP_ASSERT("check that first pbuf can hold struct tcp_hdr", |
| (p->len >= sizeof(struct tcp_hdr))); |
| |
| tcphdr = tcp_output_set_header(pcb, p, 0, htonl(pcb->snd_nxt - 1)); |
| |
| #if CHECKSUM_GEN_TCP |
| tcphdr->chksum = inet_chksum_pseudo(p, &pcb->local_ip, &pcb->remote_ip, |
| IP_PROTO_TCP, p->tot_len); |
| #endif |
| TCP_STATS_INC(tcp.xmit); |
| |
| /* Send output to IP */ |
| #if LWIP_NETIF_HWADDRHINT |
| ip_output_hinted(p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl, 0, IP_PROTO_TCP, |
| &(pcb->addr_hint)); |
| #else /* LWIP_NETIF_HWADDRHINT*/ |
| ip_output(p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl, 0, IP_PROTO_TCP); |
| #endif /* LWIP_NETIF_HWADDRHINT*/ |
| |
| pbuf_free(p); |
| |
| LWIP_DEBUGF(TCP_DEBUG, ("tcp_keepalive: seqno %"U32_F" ackno %"U32_F".\n", |
| pcb->snd_nxt - 1, pcb->rcv_nxt)); |
| } |
| |
| |
| /** |
| * Send persist timer zero-window probes to keep a connection active |
| * when a window update is lost. |
| * |
| * Called by tcp_slowtmr() |
| * |
| * @param pcb the tcp_pcb for which to send a zero-window probe packet |
| */ |
| void |
| tcp_zero_window_probe(struct tcp_pcb *pcb) |
| { |
| struct pbuf *p; |
| struct tcp_hdr *tcphdr; |
| struct tcp_seg *seg; |
| u16_t len; |
| u8_t is_fin; |
| |
| LWIP_DEBUGF(TCP_DEBUG, |
| ("tcp_zero_window_probe: sending ZERO WINDOW probe to %" |
| U16_F".%"U16_F".%"U16_F".%"U16_F"\n", |
| ip4_addr1(&pcb->remote_ip), ip4_addr2(&pcb->remote_ip), |
| ip4_addr3(&pcb->remote_ip), ip4_addr4(&pcb->remote_ip))); |
| |
| LWIP_DEBUGF(TCP_DEBUG, |
| ("tcp_zero_window_probe: tcp_ticks %"U32_F |
| " pcb->tmr %"U32_F" pcb->keep_cnt_sent %"U16_F"\n", |
| tcp_ticks, pcb->tmr, pcb->keep_cnt_sent)); |
| |
| seg = pcb->unacked; |
| |
| if(seg == NULL) |
| seg = pcb->unsent; |
| |
| if(seg == NULL) |
| return; |
| |
| is_fin = ((TCPH_FLAGS(seg->tcphdr) & TCP_FIN) != 0) && (seg->len == 0); |
| len = is_fin ? TCP_HLEN : TCP_HLEN + 1; |
| |
| p = pbuf_alloc(PBUF_IP, len, PBUF_RAM); |
| if(p == NULL) { |
| LWIP_DEBUGF(TCP_DEBUG, ("tcp_zero_window_probe: no memory for pbuf\n")); |
| return; |
| } |
| LWIP_ASSERT("check that first pbuf can hold struct tcp_hdr", |
| (p->len >= sizeof(struct tcp_hdr))); |
| |
| tcphdr = tcp_output_set_header(pcb, p, 0, seg->tcphdr->seqno); |
| |
| if (is_fin) { |
| /* FIN segment, no data */ |
| TCPH_FLAGS_SET(tcphdr, TCP_ACK | TCP_FIN); |
| } else { |
| /* Data segment, copy in one byte from the head of the unacked queue */ |
| *((char *)p->payload + sizeof(struct tcp_hdr)) = *(char *)seg->dataptr; |
| } |
| |
| #if CHECKSUM_GEN_TCP |
| tcphdr->chksum = inet_chksum_pseudo(p, &pcb->local_ip, &pcb->remote_ip, |
| IP_PROTO_TCP, p->tot_len); |
| #endif |
| TCP_STATS_INC(tcp.xmit); |
| |
| /* Send output to IP */ |
| #if LWIP_NETIF_HWADDRHINT |
| ip_output_hinted(p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl, 0, IP_PROTO_TCP, |
| &(pcb->addr_hint)); |
| #else /* LWIP_NETIF_HWADDRHINT*/ |
| ip_output(p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl, 0, IP_PROTO_TCP); |
| #endif /* LWIP_NETIF_HWADDRHINT*/ |
| |
| pbuf_free(p); |
| |
| LWIP_DEBUGF(TCP_DEBUG, ("tcp_zero_window_probe: seqno %"U32_F |
| " ackno %"U32_F".\n", |
| pcb->snd_nxt - 1, pcb->rcv_nxt)); |
| } |
| #endif /* LWIP_TCP */ |