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tcp_out: move around functions to group them together
This file has been a mess regarding the order of the functions. By moving them around, they can be grouped into functions taking part in normal data transmission (via unsent/unacked) and control segments (which are allocated, directly sent and freed). Signed-off-by: goldsimon <goldsimon@gmx.de>
This commit is contained in:
goldsimon
parent
dd6c43ecbd
commit
fdbc9f9b32
@ -14,13 +14,18 @@
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* - @ref tcp_enqueue_flags : creates SYN-only or FIN-only segments
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* - @ref tcp_output / tcp_output_segment : finalize the tcp header
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* (e.g. sequence numbers, options, checksum) and output to IP
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* - the various tcp_rexmit functions shuffle around segments between the
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* unsent an unacked lists to retransmit them
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* - tcp_create_segment and tcp_pbuf_prealloc allocate pbuf and
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* segment for these functions
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* - direct send: these segments don't contain data but control the connection
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* behaviour. They are created as pbuf only and sent directly without
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* enqueueing them:
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* - @ref tcp_send_empty_ack
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* - @ref tcp_rst
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* - @ref tcp_keepalive
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* - @ref tcp_zero_window_probe
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* - @ref tcp_send_empty_ack sends an ACK-only segment
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* - @ref tcp_rst sends a RST segment
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* - @ref tcp_keepalive sends a keepalive segment
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* - @ref tcp_zero_window_probe sends a window probe segment
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* - tcp_output_alloc_header allocates a header-only pbuf for these functions
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*/
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/*
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@ -124,69 +129,6 @@ tcp_route(const struct tcp_pcb *pcb, const ip_addr_t *src, const ip_addr_t *dst)
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}
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}
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/** Allocate a pbuf and create a tcphdr at p->payload, used for output
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* functions other than the default tcp_output -> tcp_output_segment
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* (e.g. tcp_send_empty_ack, etc.)
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*
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* @param pcb tcp pcb for which to send a packet (used to initialize tcp_hdr)
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* @param optlen length of header-options
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* @param datalen length of tcp data to reserve in pbuf
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* @param seqno_be seqno in network byte order (big-endian)
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* @return pbuf with p->payload being the tcp_hdr
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*/
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static struct pbuf *
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tcp_output_alloc_header(struct tcp_pcb *pcb, u16_t optlen, u16_t datalen,
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u32_t seqno_be /* already in network byte order */)
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{
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struct tcp_hdr *tcphdr;
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struct pbuf *p = pbuf_alloc(PBUF_IP, TCP_HLEN + optlen + datalen, PBUF_RAM);
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if (p != NULL) {
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LWIP_ASSERT("check that first pbuf can hold struct tcp_hdr",
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(p->len >= TCP_HLEN + optlen));
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tcphdr = (struct tcp_hdr *)p->payload;
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tcphdr->src = lwip_htons(pcb->local_port);
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tcphdr->dest = lwip_htons(pcb->remote_port);
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tcphdr->seqno = seqno_be;
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tcphdr->ackno = lwip_htonl(pcb->rcv_nxt);
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TCPH_HDRLEN_FLAGS_SET(tcphdr, (5 + optlen / 4), TCP_ACK);
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tcphdr->wnd = lwip_htons(TCPWND_MIN16(RCV_WND_SCALE(pcb, pcb->rcv_ann_wnd)));
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tcphdr->chksum = 0;
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tcphdr->urgp = 0;
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/* If we're sending a packet, update the announced right window edge */
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pcb->rcv_ann_right_edge = pcb->rcv_nxt + pcb->rcv_ann_wnd;
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}
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return p;
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}
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/**
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* Called by tcp_close() to send a segment including FIN flag but not data.
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* This FIN may be added to an existing segment or a new, otherwise empty
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* segment is enqueued.
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*
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* @param pcb the tcp_pcb over which to send a segment
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* @return ERR_OK if sent, another err_t otherwise
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*/
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err_t
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tcp_send_fin(struct tcp_pcb *pcb)
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{
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/* first, try to add the fin to the last unsent segment */
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if (pcb->unsent != NULL) {
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struct tcp_seg *last_unsent;
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for (last_unsent = pcb->unsent; last_unsent->next != NULL;
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last_unsent = last_unsent->next);
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if ((TCPH_FLAGS(last_unsent->tcphdr) & (TCP_SYN | TCP_FIN | TCP_RST)) == 0) {
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/* no SYN/FIN/RST flag in the header, we can add the FIN flag */
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TCPH_SET_FLAG(last_unsent->tcphdr, TCP_FIN);
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tcp_set_flags(pcb, TF_FIN);
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return ERR_OK;
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}
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}
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/* no data, no length, flags, copy=1, no optdata */
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return tcp_enqueue_flags(pcb, TCP_FIN);
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}
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/**
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* Create a TCP segment with prefilled header.
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*
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@ -841,6 +783,212 @@ memerr:
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return ERR_MEM;
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}
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/**
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* Split segment on the head of the unsent queue. If return is not
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* ERR_OK, existing head remains intact
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*
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* The split is accomplished by creating a new TCP segment and pbuf
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* which holds the remainder payload after the split. The original
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* pbuf is trimmed to new length. This allows splitting of read-only
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* pbufs
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*
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* @param pcb the tcp_pcb for which to split the unsent head
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* @param split the amount of payload to remain in the head
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*/
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err_t
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tcp_split_unsent_seg(struct tcp_pcb *pcb, u16_t split)
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{
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struct tcp_seg *seg = NULL, *useg = NULL;
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struct pbuf *p = NULL;
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u8_t optlen;
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u8_t optflags;
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u8_t split_flags;
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u8_t remainder_flags;
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u16_t remainder;
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u16_t offset;
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#if TCP_CHECKSUM_ON_COPY
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u16_t chksum = 0;
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u8_t chksum_swapped = 0;
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struct pbuf *q;
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#endif /* TCP_CHECKSUM_ON_COPY */
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useg = pcb->unsent;
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if (useg == NULL) {
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return ERR_MEM;
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}
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if (split == 0) {
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LWIP_ASSERT("Can't split segment into length 0", 0);
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return ERR_VAL;
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}
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if (useg->len <= split) {
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return ERR_OK;
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}
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LWIP_ASSERT("split <= mss", split <= pcb->mss);
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LWIP_ASSERT("useg->len > 0", useg->len > 0);
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/* We should check that we don't exceed TCP_SND_QUEUELEN but we need
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* to split this packet so we may actually exceed the max value by
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* one!
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*/
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LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_enqueue: split_unsent_seg: %u\n", (unsigned int)pcb->snd_queuelen));
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optflags = useg->flags;
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#if TCP_CHECKSUM_ON_COPY
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/* Remove since checksum is not stored until after tcp_create_segment() */
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optflags &= ~TF_SEG_DATA_CHECKSUMMED;
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#endif /* TCP_CHECKSUM_ON_COPY */
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optlen = LWIP_TCP_OPT_LENGTH(optflags);
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remainder = useg->len - split;
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/* Create new pbuf for the remainder of the split */
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p = pbuf_alloc(PBUF_TRANSPORT, remainder + optlen, PBUF_RAM);
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if (p == NULL) {
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LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_LEVEL_SERIOUS,
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("tcp_split_unsent_seg: could not allocate memory for pbuf remainder %u\n", remainder));
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goto memerr;
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}
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/* Offset into the original pbuf is past TCP/IP headers, options, and split amount */
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offset = useg->p->tot_len - useg->len + split;
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/* Copy remainder into new pbuf, headers and options will not be filled out */
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if (pbuf_copy_partial(useg->p, (u8_t *)p->payload + optlen, remainder, offset ) != remainder) {
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LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_LEVEL_SERIOUS,
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("tcp_split_unsent_seg: could not copy pbuf remainder %u\n", remainder));
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goto memerr;
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}
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#if TCP_CHECKSUM_ON_COPY
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/* calculate the checksum on remainder data */
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tcp_seg_add_chksum(~inet_chksum((const u8_t *)p->payload + optlen, remainder), remainder,
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&chksum, &chksum_swapped);
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#endif /* TCP_CHECKSUM_ON_COPY */
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/* Options are created when calling tcp_output() */
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/* Migrate flags from original segment */
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split_flags = TCPH_FLAGS(useg->tcphdr);
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remainder_flags = 0; /* ACK added in tcp_output() */
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if (split_flags & TCP_PSH) {
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split_flags &= ~TCP_PSH;
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remainder_flags |= TCP_PSH;
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}
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if (split_flags & TCP_FIN) {
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split_flags &= ~TCP_FIN;
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remainder |= TCP_FIN;
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}
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/* SYN should be left on split, RST should not be present with data */
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seg = tcp_create_segment(pcb, p, remainder_flags, lwip_ntohl(useg->tcphdr->seqno) + split, optflags);
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if (seg == NULL) {
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LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_LEVEL_SERIOUS,
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("tcp_split_unsent_seg: could not create new TCP segment\n"));
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goto memerr;
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}
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#if TCP_CHECKSUM_ON_COPY
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seg->chksum = chksum;
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seg->chksum_swapped = chksum_swapped;
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seg->flags |= TF_SEG_DATA_CHECKSUMMED;
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#endif /* TCP_CHECKSUM_ON_COPY */
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/* Remove this segment from the queue since trimming it may free pbufs */
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pcb->snd_queuelen -= pbuf_clen(useg->p);
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/* Trim the original pbuf into our split size. At this point our remainder segment must be setup
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successfully because we are modifying the original segment */
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pbuf_realloc(useg->p, useg->p->tot_len - remainder);
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useg->len -= remainder;
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TCPH_SET_FLAG(useg->tcphdr, split_flags);
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#if TCP_OVERSIZE_DBGCHECK
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/* By trimming, realloc may have actually shrunk the pbuf, so clear oversize_left */
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useg->oversize_left = 0;
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#endif /* TCP_OVERSIZE_DBGCHECK */
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/* Add back to the queue with new trimmed pbuf */
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pcb->snd_queuelen += pbuf_clen(useg->p);
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#if TCP_CHECKSUM_ON_COPY
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/* The checksum on the split segment is now incorrect. We need to re-run it over the split */
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useg->chksum = 0;
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useg->chksum_swapped = 0;
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q = useg->p;
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offset = q->tot_len - useg->len; /* Offset due to exposed headers */
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/* Advance to the pbuf where the offset ends */
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while (q != NULL && offset > q->len) {
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offset -= q->len;
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q = q->next;
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}
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LWIP_ASSERT("Found start of payload pbuf", q != NULL);
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/* Checksum the first payload pbuf accounting for offset, then other pbufs are all payload */
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for (; q != NULL; offset = 0, q = q->next) {
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tcp_seg_add_chksum(~inet_chksum((const u8_t *)q->payload + offset, q->len - offset), q->len - offset,
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&useg->chksum, &useg->chksum_swapped);
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}
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#endif /* TCP_CHECKSUM_ON_COPY */
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/* Update number of segments on the queues. Note that length now may
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* exceed TCP_SND_QUEUELEN! We don't have to touch pcb->snd_buf
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* because the total amount of data is constant when packet is split */
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pcb->snd_queuelen += pbuf_clen(seg->p);
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/* Finally insert remainder into queue after split (which stays head) */
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seg->next = useg->next;
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useg->next = seg;
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#if TCP_OVERSIZE
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/* If remainder is last segment on the unsent, ensure we clear the oversize amount
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* because the remainder is always sized to the exact remaining amount */
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if (seg->next == NULL) {
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pcb->unsent_oversize = 0;
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}
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#endif /* TCP_OVERSIZE */
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return ERR_OK;
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memerr:
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TCP_STATS_INC(tcp.memerr);
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if (seg != NULL) {
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tcp_segs_free(seg);
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}
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if (p != NULL) {
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pbuf_free(p);
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}
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return ERR_MEM;
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}
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/**
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* Called by tcp_close() to send a segment including FIN flag but not data.
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* This FIN may be added to an existing segment or a new, otherwise empty
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* segment is enqueued.
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*
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* @param pcb the tcp_pcb over which to send a segment
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* @return ERR_OK if sent, another err_t otherwise
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*/
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err_t
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tcp_send_fin(struct tcp_pcb *pcb)
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{
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/* first, try to add the fin to the last unsent segment */
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if (pcb->unsent != NULL) {
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struct tcp_seg *last_unsent;
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for (last_unsent = pcb->unsent; last_unsent->next != NULL;
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last_unsent = last_unsent->next);
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if ((TCPH_FLAGS(last_unsent->tcphdr) & (TCP_SYN | TCP_FIN | TCP_RST)) == 0) {
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/* no SYN/FIN/RST flag in the header, we can add the FIN flag */
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TCPH_SET_FLAG(last_unsent->tcphdr, TCP_FIN);
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tcp_set_flags(pcb, TF_FIN);
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return ERR_OK;
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}
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}
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/* no data, no length, flags, copy=1, no optdata */
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return tcp_enqueue_flags(pcb, TCP_FIN);
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}
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/**
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* Enqueue SYN or FIN for transmission.
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*
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@ -1035,106 +1183,6 @@ tcp_build_wnd_scale_option(u32_t *opts)
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}
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#endif
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/**
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* Send an ACK without data.
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*
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* @param pcb Protocol control block for the TCP connection to send the ACK
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*/
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err_t
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tcp_send_empty_ack(struct tcp_pcb *pcb)
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{
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err_t err;
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struct pbuf *p;
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u8_t optlen = 0;
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struct netif *netif;
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#if CHECKSUM_GEN_TCP || LWIP_TCP_TIMESTAMPS || LWIP_TCP_SACK_OUT
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struct tcp_hdr *tcphdr;
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#if LWIP_TCP_TIMESTAMPS || LWIP_TCP_SACK_OUT
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u32_t *opts;
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#if LWIP_TCP_SACK_OUT
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u8_t num_sacks;
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#endif /* LWIP_TCP_SACK_OUT */
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#endif /* LWIP_TCP_TIMESTAMPS || LWIP_TCP_SACK_OUT */
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#endif /* CHECKSUM_GEN_TCP || LWIP_TCP_TIMESTAMPS || LWIP_TCP_SACK_OUT */
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#if LWIP_TCP_TIMESTAMPS
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if (pcb->flags & TF_TIMESTAMP) {
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optlen = LWIP_TCP_OPT_LENGTH(TF_SEG_OPTS_TS);
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}
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#endif
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#if LWIP_TCP_SACK_OUT
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/* For now, SACKs are only sent with empty ACKs */
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if ((num_sacks = tcp_get_num_sacks(pcb, optlen)) > 0) {
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optlen += 4 + num_sacks * 8; /* 4 bytes for header (including 2*NOP), plus 8B for each SACK */
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}
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#endif
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p = tcp_output_alloc_header(pcb, optlen, 0, lwip_htonl(pcb->snd_nxt));
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if (p == NULL) {
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/* let tcp_fasttmr retry sending this ACK */
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tcp_set_flags(pcb, TF_ACK_DELAY | TF_ACK_NOW);
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LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output: (ACK) could not allocate pbuf\n"));
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return ERR_BUF;
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}
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#if CHECKSUM_GEN_TCP || LWIP_TCP_TIMESTAMPS || LWIP_TCP_SACK_OUT
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tcphdr = (struct tcp_hdr *)p->payload;
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#if LWIP_TCP_TIMESTAMPS || LWIP_TCP_SACK_OUT
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/* cast through void* to get rid of alignment warnings */
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opts = (u32_t *)(void *)(tcphdr + 1);
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#endif /* LWIP_TCP_TIMESTAMPS || LWIP_TCP_SACK_OUT */
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#endif /* CHECKSUM_GEN_TCP || LWIP_TCP_TIMESTAMPS || LWIP_TCP_SACK_OUT */
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LWIP_DEBUGF(TCP_OUTPUT_DEBUG,
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("tcp_output: sending ACK for %"U32_F"\n", pcb->rcv_nxt));
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/* NB. MSS and window scale options are only sent on SYNs, so ignore them here */
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#if LWIP_TCP_TIMESTAMPS
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pcb->ts_lastacksent = pcb->rcv_nxt;
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if (pcb->flags & TF_TIMESTAMP) {
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tcp_build_timestamp_option(pcb, opts);
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opts += 3;
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}
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#endif
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#if LWIP_TCP_SACK_OUT
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if (num_sacks > 0) {
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tcp_build_sack_option(pcb, opts, num_sacks);
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/* 1 word for SACKs header (including 2xNOP), and 2 words for each SACK */
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opts += 1 + num_sacks * 2;
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}
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#endif
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netif = tcp_route(pcb, &pcb->local_ip, &pcb->remote_ip);
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if (netif == NULL) {
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err = ERR_RTE;
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} else {
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#if CHECKSUM_GEN_TCP
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IF__NETIF_CHECKSUM_ENABLED(netif, NETIF_CHECKSUM_GEN_TCP) {
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tcphdr->chksum = ip_chksum_pseudo(p, IP_PROTO_TCP, p->tot_len,
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&pcb->local_ip, &pcb->remote_ip);
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}
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#endif
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NETIF_SET_HINTS(netif, &(pcb->netif_hints));
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err = ip_output_if(p, &pcb->local_ip, &pcb->remote_ip,
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pcb->ttl, pcb->tos, IP_PROTO_TCP, netif);
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NETIF_RESET_HINTS(netif);
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}
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pbuf_free(p);
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if (err != ERR_OK) {
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/* let tcp_fasttmr retry sending this ACK */
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tcp_set_flags(pcb, TF_ACK_DELAY | TF_ACK_NOW);
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} else {
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/* remove ACK flags from the PCB, as we sent an empty ACK now */
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tcp_clear_flags(pcb, TF_ACK_DELAY | TF_ACK_NOW);
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}
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return err;
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}
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/**
|
||||
* @ingroup tcp_raw
|
||||
* Find out what we can send and send it
|
||||
@ -1502,75 +1550,6 @@ tcp_output_segment(struct tcp_seg *seg, struct tcp_pcb *pcb, struct netif *netif
|
||||
return err;
|
||||
}
|
||||
|
||||
/**
|
||||
* 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 pcb TCP pcb (may be NULL if no pcb is available)
|
||||
* @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(const struct tcp_pcb *pcb, u32_t seqno, u32_t ackno,
|
||||
const ip_addr_t *local_ip, const ip_addr_t *remote_ip,
|
||||
u16_t local_port, u16_t remote_port)
|
||||
{
|
||||
struct pbuf *p;
|
||||
struct tcp_hdr *tcphdr;
|
||||
struct netif *netif;
|
||||
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 = lwip_htons(local_port);
|
||||
tcphdr->dest = lwip_htons(remote_port);
|
||||
tcphdr->seqno = lwip_htonl(seqno);
|
||||
tcphdr->ackno = lwip_htonl(ackno);
|
||||
TCPH_HDRLEN_FLAGS_SET(tcphdr, TCP_HLEN / 4, TCP_RST | TCP_ACK);
|
||||
#if LWIP_WND_SCALE
|
||||
tcphdr->wnd = PP_HTONS(((TCP_WND >> TCP_RCV_SCALE) & 0xFFFF));
|
||||
#else
|
||||
tcphdr->wnd = PP_HTONS(TCP_WND);
|
||||
#endif
|
||||
tcphdr->chksum = 0;
|
||||
tcphdr->urgp = 0;
|
||||
|
||||
TCP_STATS_INC(tcp.xmit);
|
||||
MIB2_STATS_INC(mib2.tcpoutrsts);
|
||||
|
||||
netif = tcp_route(pcb, local_ip, remote_ip);
|
||||
if (netif != NULL) {
|
||||
#if CHECKSUM_GEN_TCP
|
||||
IF__NETIF_CHECKSUM_ENABLED(netif, NETIF_CHECKSUM_GEN_TCP) {
|
||||
tcphdr->chksum = ip_chksum_pseudo(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 */
|
||||
ip_output_if(p, local_ip, remote_ip, TCP_TTL, 0, IP_PROTO_TCP, netif);
|
||||
}
|
||||
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
|
||||
*
|
||||
@ -1755,6 +1734,209 @@ tcp_rexmit_fast(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 = lwip_htons(pcb->local_port);
|
||||
tcphdr->dest = lwip_htons(pcb->remote_port);
|
||||
tcphdr->seqno = seqno_be;
|
||||
tcphdr->ackno = lwip_htonl(pcb->rcv_nxt);
|
||||
TCPH_HDRLEN_FLAGS_SET(tcphdr, (5 + optlen / 4), TCP_ACK);
|
||||
tcphdr->wnd = lwip_htons(TCPWND_MIN16(RCV_WND_SCALE(pcb, 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;
|
||||
}
|
||||
|
||||
/**
|
||||
* 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 pcb TCP pcb (may be NULL if no pcb is available)
|
||||
* @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(const struct tcp_pcb *pcb, u32_t seqno, u32_t ackno,
|
||||
const ip_addr_t *local_ip, const ip_addr_t *remote_ip,
|
||||
u16_t local_port, u16_t remote_port)
|
||||
{
|
||||
struct pbuf *p;
|
||||
struct tcp_hdr *tcphdr;
|
||||
struct netif *netif;
|
||||
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 = lwip_htons(local_port);
|
||||
tcphdr->dest = lwip_htons(remote_port);
|
||||
tcphdr->seqno = lwip_htonl(seqno);
|
||||
tcphdr->ackno = lwip_htonl(ackno);
|
||||
TCPH_HDRLEN_FLAGS_SET(tcphdr, TCP_HLEN / 4, TCP_RST | TCP_ACK);
|
||||
#if LWIP_WND_SCALE
|
||||
tcphdr->wnd = PP_HTONS(((TCP_WND >> TCP_RCV_SCALE) & 0xFFFF));
|
||||
#else
|
||||
tcphdr->wnd = PP_HTONS(TCP_WND);
|
||||
#endif
|
||||
tcphdr->chksum = 0;
|
||||
tcphdr->urgp = 0;
|
||||
|
||||
TCP_STATS_INC(tcp.xmit);
|
||||
MIB2_STATS_INC(mib2.tcpoutrsts);
|
||||
|
||||
netif = tcp_route(pcb, local_ip, remote_ip);
|
||||
if (netif != NULL) {
|
||||
#if CHECKSUM_GEN_TCP
|
||||
IF__NETIF_CHECKSUM_ENABLED(netif, NETIF_CHECKSUM_GEN_TCP) {
|
||||
tcphdr->chksum = ip_chksum_pseudo(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 */
|
||||
ip_output_if(p, local_ip, remote_ip, TCP_TTL, 0, IP_PROTO_TCP, netif);
|
||||
}
|
||||
pbuf_free(p);
|
||||
LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_rst: seqno %"U32_F" ackno %"U32_F".\n", seqno, ackno));
|
||||
}
|
||||
|
||||
/**
|
||||
* 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)
|
||||
{
|
||||
err_t err;
|
||||
struct pbuf *p;
|
||||
u8_t optlen = 0;
|
||||
struct netif *netif;
|
||||
#if CHECKSUM_GEN_TCP || LWIP_TCP_TIMESTAMPS || LWIP_TCP_SACK_OUT
|
||||
struct tcp_hdr *tcphdr;
|
||||
#if LWIP_TCP_TIMESTAMPS || LWIP_TCP_SACK_OUT
|
||||
u32_t *opts;
|
||||
#if LWIP_TCP_SACK_OUT
|
||||
u8_t num_sacks;
|
||||
#endif /* LWIP_TCP_SACK_OUT */
|
||||
#endif /* LWIP_TCP_TIMESTAMPS || LWIP_TCP_SACK_OUT */
|
||||
#endif /* CHECKSUM_GEN_TCP || LWIP_TCP_TIMESTAMPS || LWIP_TCP_SACK_OUT */
|
||||
|
||||
#if LWIP_TCP_TIMESTAMPS
|
||||
if (pcb->flags & TF_TIMESTAMP) {
|
||||
optlen = LWIP_TCP_OPT_LENGTH(TF_SEG_OPTS_TS);
|
||||
}
|
||||
#endif
|
||||
|
||||
#if LWIP_TCP_SACK_OUT
|
||||
/* For now, SACKs are only sent with empty ACKs */
|
||||
if ((num_sacks = tcp_get_num_sacks(pcb, optlen)) > 0) {
|
||||
optlen += 4 + num_sacks * 8; /* 4 bytes for header (including 2*NOP), plus 8B for each SACK */
|
||||
}
|
||||
#endif
|
||||
|
||||
p = tcp_output_alloc_header(pcb, optlen, 0, lwip_htonl(pcb->snd_nxt));
|
||||
if (p == NULL) {
|
||||
/* let tcp_fasttmr retry sending this ACK */
|
||||
tcp_set_flags(pcb, TF_ACK_DELAY | TF_ACK_NOW);
|
||||
LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output: (ACK) could not allocate pbuf\n"));
|
||||
return ERR_BUF;
|
||||
}
|
||||
|
||||
#if CHECKSUM_GEN_TCP || LWIP_TCP_TIMESTAMPS || LWIP_TCP_SACK_OUT
|
||||
tcphdr = (struct tcp_hdr *)p->payload;
|
||||
#if LWIP_TCP_TIMESTAMPS || LWIP_TCP_SACK_OUT
|
||||
/* cast through void* to get rid of alignment warnings */
|
||||
opts = (u32_t *)(void *)(tcphdr + 1);
|
||||
#endif /* LWIP_TCP_TIMESTAMPS || LWIP_TCP_SACK_OUT */
|
||||
#endif /* CHECKSUM_GEN_TCP || LWIP_TCP_TIMESTAMPS || LWIP_TCP_SACK_OUT */
|
||||
|
||||
LWIP_DEBUGF(TCP_OUTPUT_DEBUG,
|
||||
("tcp_output: sending ACK for %"U32_F"\n", pcb->rcv_nxt));
|
||||
|
||||
/* NB. MSS and window scale options are only sent on SYNs, so ignore them here */
|
||||
#if LWIP_TCP_TIMESTAMPS
|
||||
pcb->ts_lastacksent = pcb->rcv_nxt;
|
||||
|
||||
if (pcb->flags & TF_TIMESTAMP) {
|
||||
tcp_build_timestamp_option(pcb, opts);
|
||||
opts += 3;
|
||||
}
|
||||
#endif
|
||||
|
||||
#if LWIP_TCP_SACK_OUT
|
||||
if (num_sacks > 0) {
|
||||
tcp_build_sack_option(pcb, opts, num_sacks);
|
||||
/* 1 word for SACKs header (including 2xNOP), and 2 words for each SACK */
|
||||
opts += 1 + num_sacks * 2;
|
||||
}
|
||||
#endif
|
||||
|
||||
netif = tcp_route(pcb, &pcb->local_ip, &pcb->remote_ip);
|
||||
if (netif == NULL) {
|
||||
err = ERR_RTE;
|
||||
} else {
|
||||
#if CHECKSUM_GEN_TCP
|
||||
IF__NETIF_CHECKSUM_ENABLED(netif, NETIF_CHECKSUM_GEN_TCP) {
|
||||
tcphdr->chksum = ip_chksum_pseudo(p, IP_PROTO_TCP, p->tot_len,
|
||||
&pcb->local_ip, &pcb->remote_ip);
|
||||
}
|
||||
#endif
|
||||
NETIF_SET_HINTS(netif, &(pcb->netif_hints));
|
||||
err = ip_output_if(p, &pcb->local_ip, &pcb->remote_ip,
|
||||
pcb->ttl, pcb->tos, IP_PROTO_TCP, netif);
|
||||
NETIF_RESET_HINTS(netif);
|
||||
}
|
||||
pbuf_free(p);
|
||||
|
||||
if (err != ERR_OK) {
|
||||
/* let tcp_fasttmr retry sending this ACK */
|
||||
tcp_set_flags(pcb, TF_ACK_DELAY | TF_ACK_NOW);
|
||||
} else {
|
||||
/* remove ACK flags from the PCB, as we sent an empty ACK now */
|
||||
tcp_clear_flags(pcb, TF_ACK_DELAY | TF_ACK_NOW);
|
||||
}
|
||||
|
||||
return err;
|
||||
}
|
||||
|
||||
/**
|
||||
* Send keepalive packets to keep a connection active although
|
||||
@ -1809,184 +1991,6 @@ tcp_keepalive(struct tcp_pcb *pcb)
|
||||
return err;
|
||||
}
|
||||
|
||||
/**
|
||||
* Split segment on the head of the unsent queue. If return is not
|
||||
* ERR_OK, existing head remains intact
|
||||
*
|
||||
* The split is accomplished by creating a new TCP segment and pbuf
|
||||
* which holds the remainder payload after the split. The original
|
||||
* pbuf is trimmed to new length. This allows splitting of read-only
|
||||
* pbufs
|
||||
*
|
||||
* @param pcb the tcp_pcb for which to split the unsent head
|
||||
* @param split the amount of payload to remain in the head
|
||||
*/
|
||||
err_t
|
||||
tcp_split_unsent_seg(struct tcp_pcb *pcb, u16_t split)
|
||||
{
|
||||
struct tcp_seg *seg = NULL, *useg = NULL;
|
||||
struct pbuf *p = NULL;
|
||||
u8_t optlen;
|
||||
u8_t optflags;
|
||||
u8_t split_flags;
|
||||
u8_t remainder_flags;
|
||||
u16_t remainder;
|
||||
u16_t offset;
|
||||
#if TCP_CHECKSUM_ON_COPY
|
||||
u16_t chksum = 0;
|
||||
u8_t chksum_swapped = 0;
|
||||
struct pbuf *q;
|
||||
#endif /* TCP_CHECKSUM_ON_COPY */
|
||||
|
||||
useg = pcb->unsent;
|
||||
if (useg == NULL) {
|
||||
return ERR_MEM;
|
||||
}
|
||||
|
||||
if (split == 0) {
|
||||
LWIP_ASSERT("Can't split segment into length 0", 0);
|
||||
return ERR_VAL;
|
||||
}
|
||||
|
||||
if (useg->len <= split) {
|
||||
return ERR_OK;
|
||||
}
|
||||
|
||||
LWIP_ASSERT("split <= mss", split <= pcb->mss);
|
||||
LWIP_ASSERT("useg->len > 0", useg->len > 0);
|
||||
|
||||
/* We should check that we don't exceed TCP_SND_QUEUELEN but we need
|
||||
* to split this packet so we may actually exceed the max value by
|
||||
* one!
|
||||
*/
|
||||
LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_enqueue: split_unsent_seg: %u\n", (unsigned int)pcb->snd_queuelen));
|
||||
|
||||
optflags = useg->flags;
|
||||
#if TCP_CHECKSUM_ON_COPY
|
||||
/* Remove since checksum is not stored until after tcp_create_segment() */
|
||||
optflags &= ~TF_SEG_DATA_CHECKSUMMED;
|
||||
#endif /* TCP_CHECKSUM_ON_COPY */
|
||||
optlen = LWIP_TCP_OPT_LENGTH(optflags);
|
||||
remainder = useg->len - split;
|
||||
|
||||
/* Create new pbuf for the remainder of the split */
|
||||
p = pbuf_alloc(PBUF_TRANSPORT, remainder + optlen, PBUF_RAM);
|
||||
if (p == NULL) {
|
||||
LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_LEVEL_SERIOUS,
|
||||
("tcp_split_unsent_seg: could not allocate memory for pbuf remainder %u\n", remainder));
|
||||
goto memerr;
|
||||
}
|
||||
|
||||
/* Offset into the original pbuf is past TCP/IP headers, options, and split amount */
|
||||
offset = useg->p->tot_len - useg->len + split;
|
||||
/* Copy remainder into new pbuf, headers and options will not be filled out */
|
||||
if (pbuf_copy_partial(useg->p, (u8_t *)p->payload + optlen, remainder, offset ) != remainder) {
|
||||
LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_LEVEL_SERIOUS,
|
||||
("tcp_split_unsent_seg: could not copy pbuf remainder %u\n", remainder));
|
||||
goto memerr;
|
||||
}
|
||||
#if TCP_CHECKSUM_ON_COPY
|
||||
/* calculate the checksum on remainder data */
|
||||
tcp_seg_add_chksum(~inet_chksum((const u8_t *)p->payload + optlen, remainder), remainder,
|
||||
&chksum, &chksum_swapped);
|
||||
#endif /* TCP_CHECKSUM_ON_COPY */
|
||||
|
||||
/* Options are created when calling tcp_output() */
|
||||
|
||||
/* Migrate flags from original segment */
|
||||
split_flags = TCPH_FLAGS(useg->tcphdr);
|
||||
remainder_flags = 0; /* ACK added in tcp_output() */
|
||||
|
||||
if (split_flags & TCP_PSH) {
|
||||
split_flags &= ~TCP_PSH;
|
||||
remainder_flags |= TCP_PSH;
|
||||
}
|
||||
if (split_flags & TCP_FIN) {
|
||||
split_flags &= ~TCP_FIN;
|
||||
remainder |= TCP_FIN;
|
||||
}
|
||||
/* SYN should be left on split, RST should not be present with data */
|
||||
|
||||
seg = tcp_create_segment(pcb, p, remainder_flags, lwip_ntohl(useg->tcphdr->seqno) + split, optflags);
|
||||
if (seg == NULL) {
|
||||
LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_LEVEL_SERIOUS,
|
||||
("tcp_split_unsent_seg: could not create new TCP segment\n"));
|
||||
goto memerr;
|
||||
}
|
||||
|
||||
#if TCP_CHECKSUM_ON_COPY
|
||||
seg->chksum = chksum;
|
||||
seg->chksum_swapped = chksum_swapped;
|
||||
seg->flags |= TF_SEG_DATA_CHECKSUMMED;
|
||||
#endif /* TCP_CHECKSUM_ON_COPY */
|
||||
|
||||
/* Remove this segment from the queue since trimming it may free pbufs */
|
||||
pcb->snd_queuelen -= pbuf_clen(useg->p);
|
||||
|
||||
/* Trim the original pbuf into our split size. At this point our remainder segment must be setup
|
||||
successfully because we are modifying the original segment */
|
||||
pbuf_realloc(useg->p, useg->p->tot_len - remainder);
|
||||
useg->len -= remainder;
|
||||
TCPH_SET_FLAG(useg->tcphdr, split_flags);
|
||||
#if TCP_OVERSIZE_DBGCHECK
|
||||
/* By trimming, realloc may have actually shrunk the pbuf, so clear oversize_left */
|
||||
useg->oversize_left = 0;
|
||||
#endif /* TCP_OVERSIZE_DBGCHECK */
|
||||
|
||||
/* Add back to the queue with new trimmed pbuf */
|
||||
pcb->snd_queuelen += pbuf_clen(useg->p);
|
||||
|
||||
#if TCP_CHECKSUM_ON_COPY
|
||||
/* The checksum on the split segment is now incorrect. We need to re-run it over the split */
|
||||
useg->chksum = 0;
|
||||
useg->chksum_swapped = 0;
|
||||
q = useg->p;
|
||||
offset = q->tot_len - useg->len; /* Offset due to exposed headers */
|
||||
|
||||
/* Advance to the pbuf where the offset ends */
|
||||
while (q != NULL && offset > q->len) {
|
||||
offset -= q->len;
|
||||
q = q->next;
|
||||
}
|
||||
LWIP_ASSERT("Found start of payload pbuf", q != NULL);
|
||||
/* Checksum the first payload pbuf accounting for offset, then other pbufs are all payload */
|
||||
for (; q != NULL; offset = 0, q = q->next) {
|
||||
tcp_seg_add_chksum(~inet_chksum((const u8_t *)q->payload + offset, q->len - offset), q->len - offset,
|
||||
&useg->chksum, &useg->chksum_swapped);
|
||||
}
|
||||
#endif /* TCP_CHECKSUM_ON_COPY */
|
||||
|
||||
/* Update number of segments on the queues. Note that length now may
|
||||
* exceed TCP_SND_QUEUELEN! We don't have to touch pcb->snd_buf
|
||||
* because the total amount of data is constant when packet is split */
|
||||
pcb->snd_queuelen += pbuf_clen(seg->p);
|
||||
|
||||
/* Finally insert remainder into queue after split (which stays head) */
|
||||
seg->next = useg->next;
|
||||
useg->next = seg;
|
||||
|
||||
#if TCP_OVERSIZE
|
||||
/* If remainder is last segment on the unsent, ensure we clear the oversize amount
|
||||
* because the remainder is always sized to the exact remaining amount */
|
||||
if (seg->next == NULL) {
|
||||
pcb->unsent_oversize = 0;
|
||||
}
|
||||
#endif /* TCP_OVERSIZE */
|
||||
|
||||
return ERR_OK;
|
||||
memerr:
|
||||
TCP_STATS_INC(tcp.memerr);
|
||||
|
||||
if (seg != NULL) {
|
||||
tcp_segs_free(seg);
|
||||
}
|
||||
if (p != NULL) {
|
||||
pbuf_free(p);
|
||||
}
|
||||
|
||||
return ERR_MEM;
|
||||
}
|
||||
|
||||
/**
|
||||
* Send persist timer zero-window probes to keep a connection active
|
||||
* when a window update is lost.
|
||||
|
||||
Loading…
Reference in New Issue
Block a user