| /** |
| * @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_impl.h" |
| #include "lwip/def.h" |
| #include "lwip/mem.h" |
| #include "lwip/memp.h" |
| #include "lwip/ip_addr.h" |
| #include "lwip/netif.h" |
| #include "lwip/inet_chksum.h" |
| #include "lwip/stats.h" |
| #include "lwip/snmp.h" |
| #include "lwip/ip6.h" |
| #include "lwip/ip6_addr.h" |
| #include "lwip/inet_chksum.h" |
| #if LWIP_TCP_TIMESTAMPS |
| #include "lwip/sys.h" |
| #endif |
| |
| #include <string.h> |
| |
| /* Define some copy-macros for checksum-on-copy so that the code looks |
| nicer by preventing too many ifdef's. */ |
| #if TCP_CHECKSUM_ON_COPY |
| #define TCP_DATA_COPY(dst, src, len, seg) do { \ |
| tcp_seg_add_chksum(LWIP_CHKSUM_COPY(dst, src, len), \ |
| len, &seg->chksum, &seg->chksum_swapped); \ |
| seg->flags |= TF_SEG_DATA_CHECKSUMMED; } while(0) |
| #define TCP_DATA_COPY2(dst, src, len, chksum, chksum_swapped) \ |
| tcp_seg_add_chksum(LWIP_CHKSUM_COPY(dst, src, len), len, chksum, chksum_swapped); |
| #else /* TCP_CHECKSUM_ON_COPY*/ |
| #define TCP_DATA_COPY(dst, src, len, seg) MEMCPY(dst, src, len) |
| #define TCP_DATA_COPY2(dst, src, len, chksum, chksum_swapped) MEMCPY(dst, src, len) |
| #endif /* TCP_CHECKSUM_ON_COPY*/ |
| |
| /** Define this to 1 for an extra check that the output checksum is valid |
| * (usefule when the checksum is generated by the application, not the stack) */ |
| #ifndef TCP_CHECKSUM_ON_COPY_SANITY_CHECK |
| #define TCP_CHECKSUM_ON_COPY_SANITY_CHECK 0 |
| #endif |
| |
| /* Forward declarations.*/ |
| static void tcp_output_segment(struct tcp_seg *seg, struct tcp_pcb *pcb); |
| |
| /** Allocate a pbuf and create a tcphdr at p->payload, used for output |
| * functions other than the default tcp_output -> tcp_output_segment |
| * (e.g. tcp_send_empty_ack, etc.) |
| * |
| * @param pcb tcp pcb for which to send a packet (used to initialize tcp_hdr) |
| * @param optlen length of header-options |
| * @param datalen length of tcp data to reserve in pbuf |
| * @param seqno_be seqno in network byte order (big-endian) |
| * @return pbuf with p->payload being the tcp_hdr |
| */ |
| static struct pbuf * |
| tcp_output_alloc_header(struct tcp_pcb *pcb, u16_t optlen, u16_t datalen, |
| u32_t seqno_be /* already in network byte order */) |
| { |
| struct tcp_hdr *tcphdr; |
| struct pbuf *p = pbuf_alloc(PBUF_IP, TCP_HLEN + optlen + datalen, PBUF_RAM); |
| if (p != NULL) { |
| LWIP_ASSERT("check that first pbuf can hold struct tcp_hdr", |
| (p->len >= TCP_HLEN + optlen)); |
| tcphdr = (struct tcp_hdr *)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_HDRLEN_FLAGS_SET(tcphdr, (5 + optlen / 4), TCP_ACK); |
| tcphdr->wnd = htons(pcb->rcv_ann_wnd); |
| tcphdr->chksum = 0; |
| tcphdr->urgp = 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 p; |
| } |
| |
| /** |
| * Called by tcp_close() to send a segment including FIN flag but not data. |
| * |
| * @param pcb the tcp_pcb over which to send a segment |
| * @return ERR_OK if sent, another err_t otherwise |
| */ |
| err_t |
| tcp_send_fin(struct tcp_pcb *pcb) |
| { |
| /* first, try to add the fin to the last unsent segment */ |
| if (pcb->unsent != NULL) { |
| struct tcp_seg *last_unsent; |
| for (last_unsent = pcb->unsent; last_unsent->next != NULL; |
| last_unsent = last_unsent->next); |
| |
| if ((TCPH_FLAGS(last_unsent->tcphdr) & (TCP_SYN | TCP_FIN | TCP_RST)) == 0) { |
| /* no SYN/FIN/RST flag in the header, we can add the FIN flag */ |
| TCPH_SET_FLAG(last_unsent->tcphdr, TCP_FIN); |
| pcb->flags |= TF_FIN; |
| return ERR_OK; |
| } |
| } |
| /* no data, no length, flags, copy=1, no optdata */ |
| return tcp_enqueue_flags(pcb, TCP_FIN); |
| } |
| |
| /** |
| * Create a TCP segment with prefilled header. |
| * |
| * Called by tcp_write and tcp_enqueue_flags. |
| * |
| * @param pcb Protocol control block for the TCP connection. |
| * @param p pbuf that is used to hold the TCP header. |
| * @param flags TCP flags for header. |
| * @param seqno TCP sequence number of this packet |
| * @param optflags options to include in TCP header |
| * @return a new tcp_seg pointing to p, or NULL. |
| * The TCP header is filled in except ackno and wnd. |
| * p is freed on failure. |
| */ |
| static struct tcp_seg * |
| tcp_create_segment(struct tcp_pcb *pcb, struct pbuf *p, u8_t flags, u32_t seqno, u8_t optflags) |
| { |
| struct tcp_seg *seg; |
| u8_t optlen = LWIP_TCP_OPT_LENGTH(optflags); |
| |
| if ((seg = (struct tcp_seg *)memp_malloc(MEMP_TCP_SEG)) == NULL) { |
| LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_create_segment: no memory.\n")); |
| pbuf_free(p); |
| return NULL; |
| } |
| seg->flags = optflags; |
| seg->next = NULL; |
| seg->p = p; |
| seg->len = p->tot_len - optlen; |
| #if TCP_OVERSIZE_DBGCHECK |
| seg->oversize_left = 0; |
| #endif /* TCP_OVERSIZE_DBGCHECK */ |
| #if TCP_CHECKSUM_ON_COPY |
| seg->chksum = 0; |
| seg->chksum_swapped = 0; |
| /* check optflags */ |
| LWIP_ASSERT("invalid optflags passed: TF_SEG_DATA_CHECKSUMMED", |
| (optflags & TF_SEG_DATA_CHECKSUMMED) == 0); |
| #endif /* TCP_CHECKSUM_ON_COPY */ |
| |
| /* build TCP header */ |
| if (pbuf_header(p, TCP_HLEN)) { |
| LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_create_segment: no room for TCP header in pbuf.\n")); |
| TCP_STATS_INC(tcp.err); |
| tcp_seg_free(seg); |
| return NULL; |
| } |
| seg->tcphdr = (struct tcp_hdr *)seg->p->payload; |
| seg->tcphdr->src = htons(pcb->local_port); |
| seg->tcphdr->dest = htons(pcb->remote_port); |
| seg->tcphdr->seqno = htonl(seqno); |
| /* ackno is set in tcp_output */ |
| TCPH_HDRLEN_FLAGS_SET(seg->tcphdr, (5 + optlen / 4), flags); |
| /* wnd and chksum are set in tcp_output */ |
| seg->tcphdr->urgp = 0; |
| return seg; |
| } |
| |
| /** |
| * Allocate a PBUF_RAM pbuf, perhaps with extra space at the end. |
| * |
| * This function is like pbuf_alloc(layer, length, PBUF_RAM) except |
| * there may be extra bytes available at the end. |
| * |
| * @param layer flag to define header size. |
| * @param length size of the pbuf's payload. |
| * @param max_length maximum usable size of payload+oversize. |
| * @param oversize pointer to a u16_t that will receive the number of usable tail bytes. |
| * @param pcb The TCP connection that willo enqueue the pbuf. |
| * @param apiflags API flags given to tcp_write. |
| * @param first_seg true when this pbuf will be used in the first enqueued segment. |
| * @param |
| */ |
| #if TCP_OVERSIZE |
| static struct pbuf * |
| tcp_pbuf_prealloc(pbuf_layer layer, u16_t length, u16_t max_length, |
| u16_t *oversize, struct tcp_pcb *pcb, u8_t apiflags, |
| u8_t first_seg) |
| { |
| struct pbuf *p; |
| u16_t alloc = length; |
| |
| #if LWIP_NETIF_TX_SINGLE_PBUF |
| LWIP_UNUSED_ARG(max_length); |
| LWIP_UNUSED_ARG(pcb); |
| LWIP_UNUSED_ARG(apiflags); |
| LWIP_UNUSED_ARG(first_seg); |
| /* always create MSS-sized pbufs */ |
| alloc = max_length; |
| #else /* LWIP_NETIF_TX_SINGLE_PBUF */ |
| if (length < max_length) { |
| /* Should we allocate an oversized pbuf, or just the minimum |
| * length required? If tcp_write is going to be called again |
| * before this segment is transmitted, we want the oversized |
| * buffer. If the segment will be transmitted immediately, we can |
| * save memory by allocating only length. We use a simple |
| * heuristic based on the following information: |
| * |
| * Did the user set TCP_WRITE_FLAG_MORE? |
| * |
| * Will the Nagle algorithm defer transmission of this segment? |
| */ |
| if ((apiflags & TCP_WRITE_FLAG_MORE) || |
| (!(pcb->flags & TF_NODELAY) && |
| (!first_seg || |
| pcb->unsent != NULL || |
| pcb->unacked != NULL))) { |
| alloc = LWIP_MIN(max_length, LWIP_MEM_ALIGN_SIZE(length + TCP_OVERSIZE)); |
| } |
| } |
| #endif /* LWIP_NETIF_TX_SINGLE_PBUF */ |
| p = pbuf_alloc(layer, alloc, PBUF_RAM); |
| if (p == NULL) { |
| return NULL; |
| } |
| LWIP_ASSERT("need unchained pbuf", p->next == NULL); |
| *oversize = p->len - length; |
| /* trim p->len to the currently used size */ |
| p->len = p->tot_len = length; |
| return p; |
| } |
| #else /* TCP_OVERSIZE */ |
| #define tcp_pbuf_prealloc(layer, length, mx, os, pcb, api, fst) pbuf_alloc((layer), (length), PBUF_RAM) |
| #endif /* TCP_OVERSIZE */ |
| |
| #if TCP_CHECKSUM_ON_COPY |
| /** Add a checksum of newly added data to the segment */ |
| static void |
| tcp_seg_add_chksum(u16_t chksum, u16_t len, u16_t *seg_chksum, |
| u8_t *seg_chksum_swapped) |
| { |
| u32_t helper; |
| /* add chksum to old chksum and fold to u16_t */ |
| helper = chksum + *seg_chksum; |
| chksum = FOLD_U32T(helper); |
| if ((len & 1) != 0) { |
| *seg_chksum_swapped = 1 - *seg_chksum_swapped; |
| chksum = SWAP_BYTES_IN_WORD(chksum); |
| } |
| *seg_chksum = chksum; |
| } |
| #endif /* TCP_CHECKSUM_ON_COPY */ |
| |
| /** Checks if tcp_write is allowed or not (checks state, snd_buf and snd_queuelen). |
| * |
| * @param pcb the tcp pcb to check for |
| * @param len length of data to send (checked agains snd_buf) |
| * @return ERR_OK if tcp_write is allowed to proceed, another err_t otherwise |
| */ |
| static err_t |
| tcp_write_checks(struct tcp_pcb *pcb, u16_t len) |
| { |
| /* connection is in invalid state for data transmission? */ |
| if ((pcb->state != ESTABLISHED) && |
| (pcb->state != CLOSE_WAIT) && |
| (pcb->state != SYN_SENT) && |
| (pcb->state != SYN_RCVD)) { |
| LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_STATE | LWIP_DBG_LEVEL_SEVERE, ("tcp_write() called in invalid state\n")); |
| return ERR_CONN; |
| } else if (len == 0) { |
| return ERR_OK; |
| } |
| |
| /* fail on too much data */ |
| if (len > pcb->snd_buf) { |
| LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 3, ("tcp_write: too much data (len=%"U16_F" > snd_buf=%"U16_F")\n", |
| len, pcb->snd_buf)); |
| pcb->flags |= TF_NAGLEMEMERR; |
| return ERR_MEM; |
| } |
| |
| LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_write: 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 */ |
| /* check for configured max queuelen and possible overflow */ |
| if ((pcb->snd_queuelen >= TCP_SND_QUEUELEN) || (pcb->snd_queuelen > TCP_SNDQUEUELEN_OVERFLOW)) { |
| LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 3, ("tcp_write: too long queue %"U16_F" (max %"U16_F")\n", |
| pcb->snd_queuelen, TCP_SND_QUEUELEN)); |
| TCP_STATS_INC(tcp.memerr); |
| pcb->flags |= TF_NAGLEMEMERR; |
| return ERR_MEM; |
| } |
| if (pcb->snd_queuelen != 0) { |
| LWIP_ASSERT("tcp_write: pbufs on queue => at least one queue non-empty", |
| pcb->unacked != NULL || pcb->unsent != NULL); |
| } else { |
| LWIP_ASSERT("tcp_write: no pbufs on queue => both queues empty", |
| pcb->unacked == NULL && pcb->unsent == NULL); |
| } |
| return ERR_OK; |
| } |
| |
| /** |
| * 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 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 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 |
| */ |
| err_t |
| tcp_write(struct tcp_pcb *pcb, const void *arg, u16_t len, u8_t apiflags) |
| { |
| struct pbuf *concat_p = NULL; |
| struct tcp_seg *last_unsent = NULL, *seg = NULL, *prev_seg = NULL, *queue = NULL; |
| u16_t pos = 0; /* position in 'arg' data */ |
| u16_t queuelen; |
| u8_t optlen = 0; |
| u8_t optflags = 0; |
| #if TCP_OVERSIZE |
| u16_t oversize = 0; |
| u16_t oversize_used = 0; |
| #endif /* TCP_OVERSIZE */ |
| #if TCP_CHECKSUM_ON_COPY |
| u16_t concat_chksum = 0; |
| u8_t concat_chksum_swapped = 0; |
| u16_t concat_chksummed = 0; |
| #endif /* TCP_CHECKSUM_ON_COPY */ |
| err_t err; |
| /* don't allocate segments bigger than half the maximum window we ever received */ |
| u16_t mss_local = LWIP_MIN(pcb->mss, pcb->snd_wnd_max/2); |
| |
| #if LWIP_NETIF_TX_SINGLE_PBUF |
| /* Always copy to try to create single pbufs for TX */ |
| apiflags |= TCP_WRITE_FLAG_COPY; |
| #endif /* LWIP_NETIF_TX_SINGLE_PBUF */ |
| |
| LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_write(pcb=%p, data=%p, len=%"U16_F", apiflags=%"U16_F")\n", |
| (void *)pcb, arg, len, (u16_t)apiflags)); |
| LWIP_ERROR("tcp_write: arg == NULL (programmer violates API)", |
| arg != NULL, return ERR_ARG;); |
| |
| err = tcp_write_checks(pcb, len); |
| if (err != ERR_OK) { |
| return err; |
| } |
| queuelen = pcb->snd_queuelen; |
| |
| #if LWIP_TCP_TIMESTAMPS |
| if ((pcb->flags & TF_TIMESTAMP)) { |
| optflags = TF_SEG_OPTS_TS; |
| optlen = LWIP_TCP_OPT_LENGTH(TF_SEG_OPTS_TS); |
| } |
| #endif /* LWIP_TCP_TIMESTAMPS */ |
| |
| |
| /* |
| * TCP segmentation is done in three phases with increasing complexity: |
| * |
| * 1. Copy data directly into an oversized pbuf. |
| * 2. Chain a new pbuf to the end of pcb->unsent. |
| * 3. Create new segments. |
| * |
| * We may run out of memory at any point. In that case we must |
| * return ERR_MEM and not change anything in pcb. Therefore, all |
| * changes are recorded in local variables and committed at the end |
| * of the function. Some pcb fields are maintained in local copies: |
| * |
| * queuelen = pcb->snd_queuelen |
| * oversize = pcb->unsent_oversize |
| * |
| * These variables are set consistently by the phases: |
| * |
| * seg points to the last segment tampered with. |
| * |
| * pos records progress as data is segmented. |
| */ |
| |
| /* Find the tail of the unsent queue. */ |
| if (pcb->unsent != NULL) { |
| u16_t space; |
| u16_t unsent_optlen; |
| |
| /* @todo: this could be sped up by keeping last_unsent in the pcb */ |
| for (last_unsent = pcb->unsent; last_unsent->next != NULL; |
| last_unsent = last_unsent->next); |
| |
| /* Usable space at the end of the last unsent segment */ |
| unsent_optlen = LWIP_TCP_OPT_LENGTH(last_unsent->flags); |
| space = mss_local - (last_unsent->len + unsent_optlen); |
| |
| /* |
| * Phase 1: Copy data directly into an oversized pbuf. |
| * |
| * The number of bytes copied is recorded in the oversize_used |
| * variable. The actual copying is done at the bottom of the |
| * function. |
| */ |
| #if TCP_OVERSIZE |
| #if TCP_OVERSIZE_DBGCHECK |
| /* check that pcb->unsent_oversize matches last_unsent->unsent_oversize */ |
| LWIP_ASSERT("unsent_oversize mismatch (pcb vs. last_unsent)", |
| pcb->unsent_oversize == last_unsent->oversize_left); |
| #endif /* TCP_OVERSIZE_DBGCHECK */ |
| oversize = pcb->unsent_oversize; |
| if (oversize > 0) { |
| LWIP_ASSERT("inconsistent oversize vs. space", oversize_used <= space); |
| seg = last_unsent; |
| oversize_used = oversize < len ? oversize : len; |
| pos += oversize_used; |
| oversize -= oversize_used; |
| space -= oversize_used; |
| } |
| /* now we are either finished or oversize is zero */ |
| LWIP_ASSERT("inconsistend oversize vs. len", (oversize == 0) || (pos == len)); |
| #endif /* TCP_OVERSIZE */ |
| |
| /* |
| * Phase 2: Chain a new pbuf to the end of pcb->unsent. |
| * |
| * We don't extend segments containing SYN/FIN flags or options |
| * (len==0). The new pbuf is kept in concat_p and pbuf_cat'ed at |
| * the end. |
| */ |
| if ((pos < len) && (space > 0) && (last_unsent->len > 0)) { |
| u16_t seglen = space < len - pos ? space : len - pos; |
| seg = last_unsent; |
| |
| /* Create a pbuf with a copy or reference to seglen bytes. We |
| * can use PBUF_RAW here since the data appears in the middle of |
| * a segment. A header will never be prepended. */ |
| if (apiflags & TCP_WRITE_FLAG_COPY) { |
| /* Data is copied */ |
| if ((concat_p = tcp_pbuf_prealloc(PBUF_RAW, seglen, space, &oversize, pcb, apiflags, 1)) == NULL) { |
| LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, |
| ("tcp_write : could not allocate memory for pbuf copy size %"U16_F"\n", |
| seglen)); |
| goto memerr; |
| } |
| #if TCP_OVERSIZE_DBGCHECK |
| last_unsent->oversize_left += oversize; |
| #endif /* TCP_OVERSIZE_DBGCHECK */ |
| TCP_DATA_COPY2(concat_p->payload, (u8_t*)arg + pos, seglen, &concat_chksum, &concat_chksum_swapped); |
| #if TCP_CHECKSUM_ON_COPY |
| concat_chksummed += seglen; |
| #endif /* TCP_CHECKSUM_ON_COPY */ |
| } else { |
| /* Data is not copied */ |
| if ((concat_p = pbuf_alloc(PBUF_RAW, seglen, PBUF_ROM)) == NULL) { |
| LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, |
| ("tcp_write: could not allocate memory for zero-copy pbuf\n")); |
| goto memerr; |
| } |
| #if TCP_CHECKSUM_ON_COPY |
| /* calculate the checksum of nocopy-data */ |
| tcp_seg_add_chksum(~inet_chksum((u8_t*)arg + pos, seglen), seglen, |
| &concat_chksum, &concat_chksum_swapped); |
| concat_chksummed += seglen; |
| #endif /* TCP_CHECKSUM_ON_COPY */ |
| /* reference the non-volatile payload data */ |
| concat_p->payload = (u8_t*)arg + pos; |
| } |
| |
| pos += seglen; |
| queuelen += pbuf_clen(concat_p); |
| } |
| } else { |
| #if TCP_OVERSIZE |
| LWIP_ASSERT("unsent_oversize mismatch (pcb->unsent is NULL)", |
| pcb->unsent_oversize == 0); |
| #endif /* TCP_OVERSIZE */ |
| } |
| |
| /* |
| * Phase 3: Create new segments. |
| * |
| * The new segments are chained together in the local 'queue' |
| * variable, ready to be appended to pcb->unsent. |
| */ |
| while (pos < len) { |
| struct pbuf *p; |
| u16_t left = len - pos; |
| u16_t max_len = mss_local - optlen; |
| u16_t seglen = left > max_len ? max_len : left; |
| #if TCP_CHECKSUM_ON_COPY |
| u16_t chksum = 0; |
| u8_t chksum_swapped = 0; |
| #endif /* TCP_CHECKSUM_ON_COPY */ |
| |
| if (apiflags & TCP_WRITE_FLAG_COPY) { |
| /* If copy is set, memory should be allocated and data copied |
| * into pbuf */ |
| if ((p = tcp_pbuf_prealloc(PBUF_TRANSPORT, seglen + optlen, mss_local, &oversize, pcb, apiflags, queue == NULL)) == NULL) { |
| LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_write : could not allocate memory for pbuf copy size %"U16_F"\n", seglen)); |
| goto memerr; |
| } |
| LWIP_ASSERT("tcp_write: check that first pbuf can hold the complete seglen", |
| (p->len >= seglen)); |
| TCP_DATA_COPY2((char *)p->payload + optlen, (u8_t*)arg + pos, seglen, &chksum, &chksum_swapped); |
| } else { |
| /* Copy is not set: First 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. |
| */ |
| struct pbuf *p2; |
| #if TCP_OVERSIZE |
| LWIP_ASSERT("oversize == 0", oversize == 0); |
| #endif /* TCP_OVERSIZE */ |
| if ((p2 = pbuf_alloc(PBUF_TRANSPORT, seglen, PBUF_ROM)) == NULL) { |
| LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_write: could not allocate memory for zero-copy pbuf\n")); |
| goto memerr; |
| } |
| #if TCP_CHECKSUM_ON_COPY |
| /* calculate the checksum of nocopy-data */ |
| chksum = ~inet_chksum((u8_t*)arg + pos, seglen); |
| #endif /* TCP_CHECKSUM_ON_COPY */ |
| /* reference the non-volatile payload data */ |
| p2->payload = (u8_t*)arg + pos; |
| |
| /* Second, allocate a pbuf for the headers. */ |
| if ((p = pbuf_alloc(PBUF_TRANSPORT, optlen, PBUF_RAM)) == NULL) { |
| /* If allocation fails, we have to deallocate the data pbuf as |
| * well. */ |
| pbuf_free(p2); |
| LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_write: could not allocate memory for header pbuf\n")); |
| goto memerr; |
| } |
| /* Concatenate the headers and data pbufs together. */ |
| pbuf_cat(p/*header*/, p2/*data*/); |
| } |
| |
| queuelen += pbuf_clen(p); |
| |
| /* 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 | 2, ("tcp_write: queue too long %"U16_F" (%"U16_F")\n", queuelen, TCP_SND_QUEUELEN)); |
| pbuf_free(p); |
| goto memerr; |
| } |
| |
| if ((seg = tcp_create_segment(pcb, p, 0, pcb->snd_lbb + pos, optflags)) == NULL) { |
| goto memerr; |
| } |
| #if TCP_OVERSIZE_DBGCHECK |
| seg->oversize_left = oversize; |
| #endif /* TCP_OVERSIZE_DBGCHECK */ |
| #if TCP_CHECKSUM_ON_COPY |
| seg->chksum = chksum; |
| seg->chksum_swapped = chksum_swapped; |
| seg->flags |= TF_SEG_DATA_CHECKSUMMED; |
| #endif /* TCP_CHECKSUM_ON_COPY */ |
| |
| /* first segment of to-be-queued data? */ |
| if (queue == NULL) { |
| queue = seg; |
| } else { |
| /* Attach the segment to the end of the queued segments */ |
| LWIP_ASSERT("prev_seg != NULL", prev_seg != NULL); |
| prev_seg->next = seg; |
| } |
| /* remember last segment of to-be-queued data for next iteration */ |
| prev_seg = seg; |
| |
| LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_TRACE, ("tcp_write: queueing %"U32_F":%"U32_F"\n", |
| ntohl(seg->tcphdr->seqno), |
| ntohl(seg->tcphdr->seqno) + TCP_TCPLEN(seg))); |
| |
| pos += seglen; |
| } |
| |
| /* |
| * All three segmentation phases were successful. We can commit the |
| * transaction. |
| */ |
| |
| /* |
| * Phase 1: If data has been added to the preallocated tail of |
| * last_unsent, we update the length fields of the pbuf chain. |
| */ |
| #if TCP_OVERSIZE |
| if (oversize_used > 0) { |
| struct pbuf *p; |
| /* Bump tot_len of whole chain, len of tail */ |
| for (p = last_unsent->p; p; p = p->next) { |
| p->tot_len += oversize_used; |
| if (p->next == NULL) { |
| TCP_DATA_COPY((char *)p->payload + p->len, arg, oversize_used, last_unsent); |
| p->len += oversize_used; |
| } |
| } |
| last_unsent->len += oversize_used; |
| #if TCP_OVERSIZE_DBGCHECK |
| LWIP_ASSERT("last_unsent->oversize_left >= oversize_used", |
| last_unsent->oversize_left >= oversize_used); |
| last_unsent->oversize_left -= oversize_used; |
| #endif /* TCP_OVERSIZE_DBGCHECK */ |
| } |
| pcb->unsent_oversize = oversize; |
| #endif /* TCP_OVERSIZE */ |
| |
| /* |
| * Phase 2: concat_p can be concatenated onto last_unsent->p |
| */ |
| if (concat_p != NULL) { |
| LWIP_ASSERT("tcp_write: cannot concatenate when pcb->unsent is empty", |
| (last_unsent != NULL)); |
| pbuf_cat(last_unsent->p, concat_p); |
| last_unsent->len += concat_p->tot_len; |
| #if TCP_CHECKSUM_ON_COPY |
| if (concat_chksummed) { |
| tcp_seg_add_chksum(concat_chksum, concat_chksummed, &last_unsent->chksum, |
| &last_unsent->chksum_swapped); |
| last_unsent->flags |= TF_SEG_DATA_CHECKSUMMED; |
| } |
| #endif /* TCP_CHECKSUM_ON_COPY */ |
| } |
| |
| /* |
| * Phase 3: Append queue to pcb->unsent. Queue may be NULL, but that |
| * is harmless |
| */ |
| if (last_unsent == NULL) { |
| pcb->unsent = queue; |
| } else { |
| last_unsent->next = queue; |
| } |
| |
| /* |
| * Finally update the pcb state. |
| */ |
| pcb->snd_lbb += len; |
| pcb->snd_buf -= len; |
| pcb->snd_queuelen = queuelen; |
| |
| LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_write: %"S16_F" (after enqueued)\n", |
| pcb->snd_queuelen)); |
| if (pcb->snd_queuelen != 0) { |
| LWIP_ASSERT("tcp_write: valid queue length", |
| pcb->unacked != NULL || pcb->unsent != NULL); |
| } |
| |
| /* Set the PSH flag in the last segment that we enqueued. */ |
| if (seg != NULL && 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 (concat_p != NULL) { |
| pbuf_free(concat_p); |
| } |
| if (queue != NULL) { |
| tcp_segs_free(queue); |
| } |
| if (pcb->snd_queuelen != 0) { |
| LWIP_ASSERT("tcp_write: valid queue length", pcb->unacked != NULL || |
| pcb->unsent != NULL); |
| } |
| LWIP_DEBUGF(TCP_QLEN_DEBUG | LWIP_DBG_STATE, ("tcp_write: %"S16_F" (with mem err)\n", pcb->snd_queuelen)); |
| return ERR_MEM; |
| } |
| |
| /** |
| * Enqueue TCP options for transmission. |
| * |
| * Called by tcp_connect(), tcp_listen_input(), and tcp_send_ctrl(). |
| * |
| * @param pcb Protocol control block for the TCP connection. |
| * @param flags TCP header flags to set in the outgoing segment. |
| * @param optdata pointer to TCP options, or NULL. |
| * @param optlen length of TCP options in bytes. |
| */ |
| err_t |
| tcp_enqueue_flags(struct tcp_pcb *pcb, u8_t flags) |
| { |
| struct pbuf *p; |
| struct tcp_seg *seg; |
| u8_t optflags = 0; |
| u8_t optlen = 0; |
| |
| LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_enqueue_flags: queuelen: %"U16_F"\n", (u16_t)pcb->snd_queuelen)); |
| |
| LWIP_ASSERT("tcp_enqueue_flags: need either TCP_SYN or TCP_FIN in flags (programmer violates API)", |
| (flags & (TCP_SYN | TCP_FIN)) != 0); |
| |
| /* check for configured max queuelen and possible overflow */ |
| if ((pcb->snd_queuelen >= TCP_SND_QUEUELEN) || (pcb->snd_queuelen > TCP_SNDQUEUELEN_OVERFLOW)) { |
| LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 3, ("tcp_enqueue_flags: too long queue %"U16_F" (max %"U16_F")\n", |
| pcb->snd_queuelen, TCP_SND_QUEUELEN)); |
| TCP_STATS_INC(tcp.memerr); |
| pcb->flags |= TF_NAGLEMEMERR; |
| return ERR_MEM; |
| } |
| |
| if (flags & TCP_SYN) { |
| optflags = TF_SEG_OPTS_MSS; |
| } |
| #if LWIP_TCP_TIMESTAMPS |
| if ((pcb->flags & TF_TIMESTAMP)) { |
| optflags |= TF_SEG_OPTS_TS; |
| } |
| #endif /* LWIP_TCP_TIMESTAMPS */ |
| optlen = LWIP_TCP_OPT_LENGTH(optflags); |
| |
| /* tcp_enqueue_flags is always called with either SYN or FIN in flags. |
| * We need one available snd_buf byte to do that. |
| * This means we can't send FIN while snd_buf==0. A better fix would be to |
| * not include SYN and FIN sequence numbers in the snd_buf count. */ |
| if (pcb->snd_buf == 0) { |
| LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 3, ("tcp_enqueue_flags: no send buffer available\n")); |
| TCP_STATS_INC(tcp.memerr); |
| return ERR_MEM; |
| } |
| |
| /* Allocate pbuf with room for TCP header + options */ |
| if ((p = pbuf_alloc(PBUF_TRANSPORT, optlen, PBUF_RAM)) == NULL) { |
| pcb->flags |= TF_NAGLEMEMERR; |
| TCP_STATS_INC(tcp.memerr); |
| return ERR_MEM; |
| } |
| LWIP_ASSERT("tcp_enqueue_flags: check that first pbuf can hold optlen", |
| (p->len >= optlen)); |
| |
| /* Allocate memory for tcp_seg, and fill in fields. */ |
| if ((seg = tcp_create_segment(pcb, p, flags, pcb->snd_lbb, optflags)) == NULL) { |
| pcb->flags |= TF_NAGLEMEMERR; |
| TCP_STATS_INC(tcp.memerr); |
| return ERR_MEM; |
| } |
| LWIP_ASSERT("seg->tcphdr not aligned", ((mem_ptr_t)seg->tcphdr % MEM_ALIGNMENT) == 0); |
| LWIP_ASSERT("tcp_enqueue_flags: invalid segment length", seg->len == 0); |
| |
| LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_TRACE, |
| ("tcp_enqueue_flags: queueing %"U32_F":%"U32_F" (0x%"X16_F")\n", |
| ntohl(seg->tcphdr->seqno), |
| ntohl(seg->tcphdr->seqno) + TCP_TCPLEN(seg), |
| (u16_t)flags)); |
| |
| /* Now append seg to pcb->unsent queue */ |
| if (pcb->unsent == NULL) { |
| pcb->unsent = seg; |
| } else { |
| struct tcp_seg *useg; |
| for (useg = pcb->unsent; useg->next != NULL; useg = useg->next); |
| useg->next = seg; |
| } |
| #if TCP_OVERSIZE |
| /* The new unsent tail has no space */ |
| pcb->unsent_oversize = 0; |
| #endif /* TCP_OVERSIZE */ |
| |
| /* SYN and FIN bump the sequence number */ |
| if ((flags & TCP_SYN) || (flags & TCP_FIN)) { |
| pcb->snd_lbb++; |
| /* optlen does not influence snd_buf */ |
| pcb->snd_buf--; |
| } |
| if (flags & TCP_FIN) { |
| pcb->flags |= TF_FIN; |
| } |
| |
| /* update number of segments on the queues */ |
| pcb->snd_queuelen += pbuf_clen(seg->p); |
| LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_enqueue_flags: %"S16_F" (after enqueued)\n", pcb->snd_queuelen)); |
| if (pcb->snd_queuelen != 0) { |
| LWIP_ASSERT("tcp_enqueue_flags: invalid queue length", |
| pcb->unacked != NULL || pcb->unsent != NULL); |
| } |
| |
| return ERR_OK; |
| } |
| |
| #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] = PP_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 = tcp_output_alloc_header(pcb, optlen, 0, htonl(pcb->snd_nxt)); |
| if (p == NULL) { |
| LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output: (ACK) could not allocate pbuf\n")); |
| return ERR_BUF; |
| } |
| tcphdr = (struct tcp_hdr *)p->payload; |
| 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); |
| |
| /* 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 = ipX_chksum_pseudo(PCB_ISIPV6(pcb), p, IP_PROTO_TCP, p->tot_len, |
| &pcb->local_ip, &pcb->remote_ip); |
| #endif |
| ipX_output(PCB_ISIPV6(pcb), p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl, pcb->tos, |
| IP_PROTO_TCP, (struct ip_pcb *)pcb); |
| 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 */ |
| |
| /* pcb->state LISTEN not allowed here */ |
| LWIP_ASSERT("don't call tcp_output for listen-pcbs", |
| pcb->state != LISTEN); |
| |
| /* 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_write 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_write/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); |
| } |
| |
| #if TCP_OVERSIZE_DBGCHECK |
| seg->oversize_left = 0; |
| #endif /* TCP_OVERSIZE_DBGCHECK */ |
| 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 TCP_OVERSIZE |
| if (pcb->unsent == NULL) { |
| /* last unsent has been removed, reset unsent_oversize */ |
| pcb->unsent_oversize = 0; |
| } |
| #endif /* TCP_OVERSIZE */ |
| |
| 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; |
| 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 *)(void *)(seg->tcphdr + 1); |
| if (seg->flags & TF_SEG_OPTS_MSS) { |
| u16_t mss; |
| #if TCP_CALCULATE_EFF_SEND_MSS |
| mss = tcp_eff_send_mss(TCP_MSS, &pcb->local_ip, &pcb->remote_ip, PCB_ISIPV6(pcb)); |
| #else /* TCP_CALCULATE_EFF_SEND_MSS */ |
| mss = TCP_MSS; |
| #endif /* TCP_CALCULATE_EFF_SEND_MSS */ |
| *opts = TCP_BUILD_MSS_OPTION(mss); |
| 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 |
| |
| /* Set retransmission timer running if it is not currently enabled |
| This must be set before checking the route. */ |
| if (pcb->rtime == -1) { |
| pcb->rtime = 0; |
| } |
| |
| /* If we don't have a local IP address, we get one by |
| calling ip_route(). */ |
| if (ipX_addr_isany(PCB_ISIPV6(pcb), &pcb->local_ip)) { |
| struct netif *netif; |
| ipX_addr_t *local_ip; |
| ipX_route_get_local_ipX(PCB_ISIPV6(pcb), &pcb->local_ip, &pcb->remote_ip, netif, local_ip); |
| if ((netif == NULL) || (local_ip == NULL)) { |
| return; |
| } |
| ipX_addr_copy(PCB_ISIPV6(pcb), pcb->local_ip, *local_ip); |
| } |
| |
| 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 TCP_CHECKSUM_ON_COPY |
| { |
| u32_t acc; |
| #if TCP_CHECKSUM_ON_COPY_SANITY_CHECK |
| u16_t chksum_slow = ipX_chksum_pseudo(PCB_ISIPV6(pcb), seg->p, IP_PROTO_TCP, |
| seg->p->tot_len, &pcb->local_ip, &pcb->remote_ip); |
| #endif /* TCP_CHECKSUM_ON_COPY_SANITY_CHECK */ |
| if ((seg->flags & TF_SEG_DATA_CHECKSUMMED) == 0) { |
| LWIP_ASSERT("data included but not checksummed", |
| seg->p->tot_len == (TCPH_HDRLEN(seg->tcphdr) * 4)); |
| } |
| |
| /* rebuild TCP header checksum (TCP header changes for retransmissions!) */ |
| acc = ipX_chksum_pseudo_partial(PCB_ISIPV6(pcb), seg->p, IP_PROTO_TCP, |
| seg->p->tot_len, TCPH_HDRLEN(seg->tcphdr) * 4, &pcb->local_ip, &pcb->remote_ip); |
| /* add payload checksum */ |
| if (seg->chksum_swapped) { |
| seg->chksum = SWAP_BYTES_IN_WORD(seg->chksum); |
| seg->chksum_swapped = 0; |
| } |
| acc += (u16_t)~(seg->chksum); |
| seg->tcphdr->chksum = FOLD_U32T(acc); |
| #if TCP_CHECKSUM_ON_COPY_SANITY_CHECK |
| if (chksum_slow != seg->tcphdr->chksum) { |
| LWIP_DEBUGF(TCP_DEBUG | LWIP_DBG_LEVEL_WARNING, |
| ("tcp_output_segment: calculated checksum is %"X16_F" instead of %"X16_F"\n", |
| seg->tcphdr->chksum, chksum_slow)); |
| seg->tcphdr->chksum = chksum_slow; |
| } |
| #endif /* TCP_CHECKSUM_ON_COPY_SANITY_CHECK */ |
| } |
| #else /* TCP_CHECKSUM_ON_COPY */ |
| #if CHECKSUM_GEN_TCP |
| seg->tcphdr->chksum = ipX_chksum_pseudo(PCB_ISIPV6(pcb), seg->p, IP_PROTO_TCP, |
| seg->p->tot_len, &pcb->local_ip, &pcb->remote_ip); |
| #endif /* CHECKSUM_GEN_TCP */ |
| #endif /* TCP_CHECKSUM_ON_COPY */ |
| TCP_STATS_INC(tcp.xmit); |
| |
| #if TCP_OUTPUT_DEBUG |
| #if LWIP_IP_DEBUG_TARGET |
| if (debug_target_match(PCB_ISIPV6(pcb), &pcb->local_ip, &pcb->remote_ip)) |
| { |
| #endif |
| tcp_debug_print(seg->tcphdr); |
| #if LWIP_IP_DEBUG_TARGET |
| } |
| #endif |
| #endif |
| |
| ipX_output(PCB_ISIPV6(pcb), seg->p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl, |
| pcb->tos, IP_PROTO_TCP, (struct ip_pcb *)pcb); |
| } |
| |
| /** |
| * 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_impl(u32_t seqno, u32_t ackno, |
| ipX_addr_t *local_ip, ipX_addr_t *remote_ip, |
| u16_t local_port, u16_t remote_port |
| #if LWIP_IPV6 |
| , u8_t isipv6 |
| #endif /* LWIP_IPV6 */ |
| ) |
| { |
| 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 = (struct tcp_hdr *)p->payload; |
| tcphdr->src = htons(local_port); |
| tcphdr->dest = htons(remote_port); |
| tcphdr->seqno = htonl(seqno); |
| tcphdr->ackno = htonl(ackno); |
| TCPH_HDRLEN_FLAGS_SET(tcphdr, TCP_HLEN/4, TCP_RST | TCP_ACK); |
| tcphdr->wnd = PP_HTONS(TCP_WND); |
| tcphdr->chksum = 0; |
| tcphdr->urgp = 0; |
| |
| TCP_STATS_INC(tcp.xmit); |
| snmp_inc_tcpoutrsts(); |
| |
| #if CHECKSUM_GEN_TCP |
| tcphdr->chksum = ipX_chksum_pseudo(isipv6, p, IP_PROTO_TCP, p->tot_len, |
| local_ip, remote_ip); |
| #endif |
| /* Send output with hardcoded TTL/HL since we have no access to the pcb */ |
| ipX_output(isipv6, p, local_ip, remote_ip, TCP_TTL, 0, IP_PROTO_TCP, NULL); |
| 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; |
| /* last unsent hasn't changed, no need to reset unsent_oversize */ |
| |
| /* 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; |
| #if TCP_OVERSIZE |
| if (seg->next == NULL) { |
| /* the retransmitted segment is last in unsent, so reset unsent_oversize */ |
| pcb->unsent_oversize = 0; |
| } |
| #endif /* TCP_OVERSIZE */ |
| |
| ++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 ")); |
| ipX_addr_debug_print(PCB_ISIPV6(pcb), TCP_DEBUG, &pcb->remote_ip); |
| LWIP_DEBUGF(TCP_DEBUG, ("\n")); |
| |
| 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 = tcp_output_alloc_header(pcb, 0, 0, htonl(pcb->snd_nxt - 1)); |
| if(p == NULL) { |
| LWIP_DEBUGF(TCP_DEBUG, |
| ("tcp_keepalive: could not allocate memory for pbuf\n")); |
| return; |
| } |
| tcphdr = (struct tcp_hdr *)p->payload; |
| |
| tcphdr->chksum = ipX_chksum_pseudo(PCB_ISIPV6(pcb), p, IP_PROTO_TCP, p->tot_len, |
| &pcb->local_ip, &pcb->remote_ip); |
| TCP_STATS_INC(tcp.xmit); |
| |
| /* Send output to IP */ |
| ipX_output(PCB_ISIPV6(pcb), p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl, |
| 0, IP_PROTO_TCP, (struct ip_pcb *)pcb); |
| |
| 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 ")); |
| ipX_addr_debug_print(PCB_ISIPV6(pcb), TCP_DEBUG, &pcb->remote_ip); |
| LWIP_DEBUGF(TCP_DEBUG, ("\n")); |
| |
| 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); |
| /* we want to send one seqno: either FIN or data (no options) */ |
| len = is_fin ? 0 : 1; |
| |
| p = tcp_output_alloc_header(pcb, 0, len, seg->tcphdr->seqno); |
| if(p == NULL) { |
| LWIP_DEBUGF(TCP_DEBUG, ("tcp_zero_window_probe: no memory for pbuf\n")); |
| return; |
| } |
| tcphdr = (struct tcp_hdr *)p->payload; |
| |
| 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 *d = ((char *)p->payload + TCP_HLEN); |
| /* Depending on whether the segment has already been sent (unacked) or not |
| (unsent), seg->p->payload points to the IP header or TCP header. |
| Ensure we copy the first TCP data byte: */ |
| pbuf_copy_partial(seg->p, d, 1, seg->p->tot_len - seg->len); |
| } |
| |
| #if CHECKSUM_GEN_TCP |
| tcphdr->chksum = ipX_chksum_pseudo(PCB_ISIPV6(pcb), p, IP_PROTO_TCP, p->tot_len, |
| &pcb->local_ip, &pcb->remote_ip); |
| #endif |
| TCP_STATS_INC(tcp.xmit); |
| |
| /* Send output to IP */ |
| ipX_output(PCB_ISIPV6(pcb), p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl, 0, IP_PROTO_TCP, (struct ip_pcb *)pcb); |
| |
| 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 */ |