void
tcp_rst(u32_t seqno, u32_t ackno,
struct ip_addr *local_ip, struct ip_addr *remote_ip,
u16_t local_port, u16_t remote_port)
{
struct pbuf *p;
struct tcp_hdr *tcphdr;
p = pbuf_alloc(PBUF_IP, TCP_HLEN, PBUF_RAM);
if (p == NULL) {
LWIP_DEBUGF(TCP_DEBUG, ("tcp_rst: could not allocate memory for pbuf\n"));
return;
}
tcphdr = p->payload;
tcphdr->src = htons(local_port);
tcphdr->dest = htons(remote_port);
tcphdr->seqno = htonl(seqno);
tcphdr->ackno = htonl(ackno);
TCPH_FLAGS_SET(tcphdr, TCP_RST | TCP_ACK);
tcphdr->wnd = htons(TCP_WND);
tcphdr->urgp = 0;
TCPH_HDRLEN_SET(tcphdr, 5);
tcphdr->chksum = 0;
#if CHECKSUM_GEN_TCP
tcphdr->chksum = inet_chksum_pseudo(p, local_ip, remote_ip,
IP_PROTO_TCP, p->tot_len);
#endif
TCP_STATS_INC(tcp.xmit);
snmp_inc_tcpoutrsts();
/* Send output with hardcoded TTL since we have no access to the pcb */
ip_output(p, local_ip, remote_ip, TCP_TTL, 0, IP_PROTO_TCP);
pbuf_free(p);
LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_rst: seqno %"U32_F" ackno %"U32_F".\n", seqno, ackno));
}
/**
* 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.
*
* The pcb is given only when its valid and from an output context.
* It is used with the external_ip_output function.
*
* @param seqno the sequence number to use for the outgoing segment
* @param ackno the acknowledge number to use for the outgoing segment
* @param local_ip the local IP address to send the segment from
* @param remote_ip the remote IP address to send the segment to
* @param local_port the local TCP port to send the segment from
* @param remote_port the remote TCP port to send the segment to
*/
void
tcp_rst(u32_t seqno, u32_t ackno, u16_t local_port, u16_t remote_port, struct tcp_pcb *pcb)
{
struct pbuf *p;
struct tcp_hdr *tcphdr;
#if LWIP_3RD_PARTY_BUFS
if (!pcb) return;
#endif
p = tcp_tx_pbuf_alloc(pcb, 0, PBUF_RAM);
if (p == NULL) {
LWIP_DEBUGF(TCP_DEBUG, ("tcp_rst: could not allocate memory for pbuf\n"));
return;
}
pbuf_header(p, TCP_HLEN);
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 & 0xFFFF ));
tcphdr->chksum = 0;
tcphdr->urgp = 0;
TCP_STATS_INC(tcp.xmit);
/* Send output with hardcoded TTL since we have no access to the pcb */
if(pcb) pcb->ip_output(p, pcb, 0);
/* external_ip_output(p, NULL, local_ip, remote_ip, TCP_TTL, 0, IP_PROTO_TCP) */;
tcp_tx_pbuf_free(pcb, p);
LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_rst: seqno %"U32_F" ackno %"U32_F".\n", seqno, ackno));
}
/**
* Actually send a TCP segment over IP
*/
static void
tcp_output_segment(struct tcp_seg *seg, struct tcp_pcb *pcb)
{
u16_t len;
struct netif *netif;
/* The TCP header has already been constructed, but the ackno and
wnd fields remain. */
seg->tcphdr->ackno = htonl(pcb->rcv_nxt);
/* silly window avoidance */
if (pcb->rcv_wnd < pcb->mss) {
seg->tcphdr->wnd = 0;
} else {
/* advertise our receive window size in this TCP segment */
seg->tcphdr->wnd = htons(pcb->rcv_wnd);
}
/* If we don't have a local IP address, we get one by
calling ip_route(). */
if (ip_addr_isany(&(pcb->local_ip))) {
netif = ip_route(&(pcb->remote_ip));
if (netif == NULL) {
return;
}
ip_addr_set(&(pcb->local_ip), &(netif->ip_addr));
}
pcb->rtime = 0;
if (pcb->rttest == 0) {
pcb->rttest = tcp_ticks;
pcb->rtseq = ntohl(seg->tcphdr->seqno);
LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_output_segment: rtseq %"U32_F"\n", pcb->rtseq));
}
LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output_segment: %"U32_F":%"U32_F"\n",
htonl(seg->tcphdr->seqno), htonl(seg->tcphdr->seqno) +
seg->len));
len = (u16_t)((u8_t *)seg->tcphdr - (u8_t *)seg->p->payload);
seg->p->len -= len;
seg->p->tot_len -= len;
seg->p->payload = seg->tcphdr;
seg->tcphdr->chksum = 0;
#if CHECKSUM_GEN_TCP
seg->tcphdr->chksum = inet_chksum_pseudo(seg->p,
&(pcb->local_ip),
&(pcb->remote_ip),
IP_PROTO_TCP, seg->p->tot_len);
#endif
TCP_STATS_INC(tcp.xmit);
ip_output(seg->p, &(pcb->local_ip), &(pcb->remote_ip), pcb->ttl, pcb->tos,
IP_PROTO_TCP);
}
/**
* 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->dataptr = p->payload;
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;
}
/** 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 ICACHE_FLASH_ATTR
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;
}
/**
* Send keepalive packets to keep a connection active although
* no data is sent over it.
*
* Called by tcp_slowtmr()
*
* @param pcb the tcp_pcb for which to send a keepalive packet
*/
void
tcp_keepalive(struct tcp_pcb *pcb)
{
struct pbuf *p;
struct tcp_hdr *tcphdr;
LWIP_DEBUGF(TCP_DEBUG, ("tcp_keepalive: sending KEEPALIVE probe to %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
ip4_addr1_16(&pcb->remote_ip), ip4_addr2_16(&pcb->remote_ip),
ip4_addr3_16(&pcb->remote_ip), ip4_addr4_16(&pcb->remote_ip)));
LWIP_DEBUGF(TCP_DEBUG, ("tcp_keepalive: tcp_ticks %"U32_F" pcb->tmr %"U32_F" pcb->keep_cnt_sent %"U16_F"\n",
tcp_ticks, pcb->tmr, pcb->keep_cnt_sent));
p = 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;
#if CHECKSUM_GEN_TCP
tcphdr->chksum = inet_chksum_pseudo(p, &pcb->local_ip, &pcb->remote_ip,
IP_PROTO_TCP, (u16_t)p->tot_len);
#endif
TCP_STATS_INC(tcp.xmit);
/* Send output to IP */
#if LWIP_NETIF_HWADDRHINT
ip_output_hinted(p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl, 0, IP_PROTO_TCP,
&(pcb->addr_hint));
#elif LWIP_3RD_PARTY_L3
pcb->ip_output(p, pcb, 0);
#else /* LWIP_NETIF_HWADDRHINT*/
ip_output(p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl, 0, IP_PROTO_TCP);
#endif /* LWIP_NETIF_HWADDRHINT*/
tcp_tx_pbuf_free(pcb, p);
LWIP_DEBUGF(TCP_DEBUG, ("tcp_keepalive: seqno %"U32_F" ackno %"U32_F".\n",
pcb->snd_nxt - 1, pcb->rcv_nxt));
(void)tcphdr; /* Fix warning -Wunused-but-set-variable*/
}
void
tcp_keepalive(struct tcp_pcb *pcb)
{
struct pbuf *p;
struct tcp_hdr *tcphdr;
LWIP_DEBUGF(TCP_DEBUG, ("tcp_keepalive: sending KEEPALIVE probe to %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
ip4_addr1(&pcb->remote_ip), ip4_addr2(&pcb->remote_ip),
ip4_addr3(&pcb->remote_ip), ip4_addr4(&pcb->remote_ip)));
LWIP_DEBUGF(TCP_DEBUG, ("tcp_keepalive: tcp_ticks %"U32_F" pcb->tmr %"U32_F" pcb->keep_cnt %"U16_F"\n", tcp_ticks, pcb->tmr, pcb->keep_cnt));
p = pbuf_alloc(PBUF_IP, TCP_HLEN, PBUF_RAM);
if(p == NULL) {
LWIP_DEBUGF(TCP_DEBUG, ("tcp_keepalive: could not allocate memory for pbuf\n"));
return;
}
tcphdr = p->payload;
tcphdr->src = htons(pcb->local_port);
tcphdr->dest = htons(pcb->remote_port);
tcphdr->seqno = htonl(pcb->snd_nxt - 1);
tcphdr->ackno = htonl(pcb->rcv_nxt);
tcphdr->wnd = htons(pcb->rcv_wnd);
tcphdr->urgp = 0;
TCPH_HDRLEN_SET(tcphdr, 5);
tcphdr->chksum = 0;
#if CHECKSUM_GEN_TCP
tcphdr->chksum = inet_chksum_pseudo(p, &pcb->local_ip, &pcb->remote_ip, IP_PROTO_TCP, p->tot_len);
#endif
TCP_STATS_INC(tcp.xmit);
/* Send output to IP */
ip_output(p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl, 0, IP_PROTO_TCP);
pbuf_free(p);
LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_keepalive: seqno %"U32_F" ackno %"U32_F".\n", pcb->snd_nxt - 1, pcb->rcv_nxt));
}
/**
* Enqueue either data or TCP options (but not both) for tranmission
*
*
*
* @arg pcb Protocol control block for the TCP connection to enqueue data for.
* @arg arg Pointer to the data to be enqueued for sending.
* @arg len Data length in bytes
* @arg flags
* @arg copy 1 if data must be copied, 0 if data is non-volatile and can be
* referenced.
* @arg optdata
* @arg optlen
*/
err_t
tcp_enqueue(struct tcp_pcb *pcb, void *arg, u16_t len,
u8_t flags, u8_t copy,
u8_t *optdata, u8_t optlen)
{
struct pbuf *p;
struct tcp_seg *seg, *useg, *queue;
u32_t left, seqno;
u16_t seglen;
void *ptr;
u8_t queuelen;
LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_enqueue(pcb=%p, arg=%p, len=%"U16_F", flags=%"X16_F", copy=%"U16_F")\n",
(void *)pcb, arg, len, (u16_t)flags, (u16_t)copy));
LWIP_ASSERT("tcp_enqueue: len == 0 || optlen == 0 (programmer violates API)",
len == 0 || optlen == 0);
LWIP_ASSERT("tcp_enqueue: arg == NULL || optdata == NULL (programmer violates API)",
arg == NULL || optdata == NULL);
/* fail on too much data */
if (len > pcb->snd_buf) {
LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 3, ("tcp_enqueue: too much data (len=%"U16_F" > snd_buf=%"U16_F")\n", len, pcb->snd_buf));
return ERR_MEM;
}
left = len;
ptr = arg;
/* seqno will be the sequence number of the first segment enqueued
* by the call to this function. */
seqno = pcb->snd_lbb;
LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_enqueue: queuelen: %"U16_F"\n", (u16_t)pcb->snd_queuelen));
/* If total number of pbufs on the unsent/unacked queues exceeds the
* configured maximum, return an error */
queuelen = pcb->snd_queuelen;
if (queuelen >= TCP_SND_QUEUELEN) {
LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 3, ("tcp_enqueue: too long queue %"U16_F" (max %"U16_F")\n", queuelen, TCP_SND_QUEUELEN));
TCP_STATS_INC(tcp.memerr);
return ERR_MEM;
}
if (queuelen != 0) {
LWIP_ASSERT("tcp_enqueue: pbufs on queue => at least one queue non-empty",
pcb->unacked != NULL || pcb->unsent != NULL);
} else {
LWIP_ASSERT("tcp_enqueue: no pbufs on queue => both queues empty",
pcb->unacked == NULL && pcb->unsent == NULL);
}
/* First, break up the data into segments and tuck them together in
* the local "queue" variable. */
useg = queue = seg = NULL;
seglen = 0;
while (queue == NULL || left > 0) {
/* The segment length should be the MSS if the data to be enqueued
* is larger than the MSS. */
seglen = left > pcb->mss? pcb->mss: left;
/* Allocate memory for tcp_seg, and fill in fields. */
seg = memp_malloc(MEMP_TCP_SEG);
if (seg == NULL) {
LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_enqueue: could not allocate memory for tcp_seg\n"));
goto memerr;
}
seg->next = NULL;
seg->p = NULL;
/* first segment of to-be-queued data? */
if (queue == NULL) {
queue = seg;
}
/* subsequent segments of to-be-queued data */
else {
/* Attach the segment to the end of the queued segments */
LWIP_ASSERT("useg != NULL", useg != NULL);
useg->next = seg;
}
/* remember last segment of to-be-queued data for next iteration */
useg = seg;
/* If copy is set, memory should be allocated
* and data copied into pbuf, otherwise data comes from
* ROM or other static memory, and need not be copied. If
* optdata is != NULL, we have options instead of data. */
/* options? */
if (optdata != NULL) {
if ((seg->p = pbuf_alloc(PBUF_TRANSPORT, optlen, PBUF_RAM)) == NULL) {
goto memerr;
}
++queuelen;
seg->dataptr = seg->p->payload;
}
/* copy from volatile memory? */
else if (copy) {
if ((seg->p = pbuf_alloc(PBUF_TRANSPORT, seglen, PBUF_RAM)) == NULL) {
LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_enqueue : could not allocate memory for pbuf copy size %"U16_F"\n", seglen));
goto memerr;
}
++queuelen;
if (arg != NULL) {
memcpy(seg->p->payload, ptr, seglen);
}
seg->dataptr = seg->p->payload;
}
/* do not copy data */
else {
/* 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.
*/
if ((p = pbuf_alloc(PBUF_TRANSPORT, seglen, PBUF_ROM)) == NULL) {
LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_enqueue: could not allocate memory for zero-copy pbuf\n"));
goto memerr;
}
++queuelen;
/* reference the non-volatile payload data */
p->payload = ptr;
seg->dataptr = ptr;
/* Second, allocate a pbuf for the headers. */
if ((seg->p = pbuf_alloc(PBUF_TRANSPORT, 0, PBUF_RAM)) == NULL) {
/* If allocation fails, we have to deallocate the data pbuf as
* well. */
pbuf_free(p);
LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_enqueue: could not allocate memory for header pbuf\n"));
goto memerr;
}
++queuelen;
/* Concatenate the headers and data pbufs together. */
pbuf_cat(seg->p/*header*/, p/*data*/);
p = NULL;
}
/* Now that there are more segments queued, we check again if the
length of the queue exceeds the configured maximum. */
if (queuelen > TCP_SND_QUEUELEN) {
LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_enqueue: queue too long %"U16_F" (%"U16_F")\n", queuelen, TCP_SND_QUEUELEN));
goto memerr;
}
seg->len = seglen;
/* build TCP header */
if (pbuf_header(seg->p, TCP_HLEN)) {
LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_enqueue: no room for TCP header in pbuf.\n"));
TCP_STATS_INC(tcp.err);
goto memerr;
}
seg->tcphdr = seg->p->payload;
seg->tcphdr->src = htons(pcb->local_port);
seg->tcphdr->dest = htons(pcb->remote_port);
seg->tcphdr->seqno = htonl(seqno);
seg->tcphdr->urgp = 0;
TCPH_FLAGS_SET(seg->tcphdr, flags);
/* don't fill in tcphdr->ackno and tcphdr->wnd until later */
/* Copy the options into the header, if they are present. */
if (optdata == NULL) {
TCPH_HDRLEN_SET(seg->tcphdr, 5);
}
else {
TCPH_HDRLEN_SET(seg->tcphdr, (5 + optlen / 4));
/* Copy options into data portion of segment.
Options can thus only be sent in non data carrying
segments such as SYN|ACK. */
memcpy(seg->dataptr, optdata, optlen);
}
LWIP_DEBUGF(TCP_OUTPUT_DEBUG | DBG_TRACE, ("tcp_enqueue: queueing %"U32_F":%"U32_F" (0x%"X16_F")\n",
ntohl(seg->tcphdr->seqno),
ntohl(seg->tcphdr->seqno) + TCP_TCPLEN(seg),
(u16_t)flags));
left -= seglen;
seqno += seglen;
ptr = (void *)((u8_t *)ptr + seglen);
}
/* Now that the data to be enqueued has been broken up into TCP
segments in the queue variable, we add them to the end of the
pcb->unsent queue. */
if (pcb->unsent == NULL) {
useg = NULL;
}
else {
for (useg = pcb->unsent; useg->next != NULL; useg = useg->next);
}
/* { useg is last segment on the unsent queue, NULL if list is empty } */
/* If there is room in the last pbuf on the unsent queue,
chain the first pbuf on the queue together with that. */
if (useg != NULL &&
TCP_TCPLEN(useg) != 0 &&
!(TCPH_FLAGS(useg->tcphdr) & (TCP_SYN | TCP_FIN)) &&
!(flags & (TCP_SYN | TCP_FIN)) &&
/* fit within max seg size */
useg->len + queue->len <= pcb->mss) {
/* Remove TCP header from first segment of our to-be-queued list */
pbuf_header(queue->p, -TCP_HLEN);
pbuf_cat(useg->p, queue->p);
useg->len += queue->len;
useg->next = queue->next;
LWIP_DEBUGF(TCP_OUTPUT_DEBUG | DBG_TRACE | DBG_STATE, ("tcp_enqueue: chaining segments, new len %"U16_F"\n", useg->len));
if (seg == queue) {
seg = NULL;
}
memp_free(MEMP_TCP_SEG, queue);
}
else {
/* empty list */
if (useg == NULL) {
/* initialize list with this segment */
pcb->unsent = queue;
}
/* enqueue segment */
else {
useg->next = queue;
}
}
if ((flags & TCP_SYN) || (flags & TCP_FIN)) {
++len;
}
pcb->snd_lbb += len;
pcb->snd_buf -= len;
/* update number of segments on the queues */
pcb->snd_queuelen = queuelen;
LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_enqueue: %"S16_F" (after enqueued)\n", pcb->snd_queuelen));
if (pcb->snd_queuelen != 0) {
LWIP_ASSERT("tcp_enqueue: valid queue length",
pcb->unacked != NULL || pcb->unsent != NULL);
}
/* Set the PSH flag in the last segment that we enqueued, but only
if the segment has data (indicated by seglen > 0). */
if (seg != NULL && seglen > 0 && seg->tcphdr != NULL) {
TCPH_SET_FLAG(seg->tcphdr, TCP_PSH);
}
return ERR_OK;
memerr:
TCP_STATS_INC(tcp.memerr);
if (queue != NULL) {
tcp_segs_free(queue);
}
if (pcb->snd_queuelen != 0) {
LWIP_ASSERT("tcp_enqueue: valid queue length", pcb->unacked != NULL ||
pcb->unsent != NULL);
}
LWIP_DEBUGF(TCP_QLEN_DEBUG | DBG_STATE, ("tcp_enqueue: %"S16_F" (with mem err)\n", pcb->snd_queuelen));
return ERR_MEM;
}
/**
* The initial input processing of TCP. It verifies the TCP header, demultiplexes
* the segment between the PCBs and passes it on to tcp_process(), which implements
* the TCP finite state machine. This function is called by the IP layer (in
* ip_input()).
*
* @param p received TCP segment to process (p->payload pointing to the IP header)
* @param inp network interface on which this segment was received
*/
void
tcp_input(struct pbuf *p, struct netif *inp)
{
struct tcp_pcb *pcb, *prev;
struct tcp_pcb_listen *lpcb;
u8_t hdrlen;
err_t err;
PERF_START;
TCP_STATS_INC(tcp.recv);
snmp_inc_tcpinsegs();
iphdr = p->payload;
tcphdr = (struct tcp_hdr *)((u8_t *)p->payload + IPH_HL(iphdr) * 4);
#if TCP_INPUT_DEBUG
tcp_debug_print(tcphdr);
#endif
/* remove header from payload */
if (pbuf_header(p, -((s16_t)(IPH_HL(iphdr) * 4))) || (p->tot_len < sizeof(struct tcp_hdr))) {
/* drop short packets */
LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: short packet (%"U16_F" bytes) discarded\n", p->tot_len));
TCP_STATS_INC(tcp.lenerr);
TCP_STATS_INC(tcp.drop);
snmp_inc_tcpinerrs();
pbuf_free(p);
return;
}
/* Don't even process incoming broadcasts/multicasts. */
if (ip_addr_isbroadcast(&(iphdr->dest), inp) ||
ip_addr_ismulticast(&(iphdr->dest))) {
TCP_STATS_INC(tcp.proterr);
TCP_STATS_INC(tcp.drop);
snmp_inc_tcpinerrs();
pbuf_free(p);
return;
}
#if CHECKSUM_CHECK_TCP
/* Verify TCP checksum. */
if (inet_chksum_pseudo(p, (struct ip_addr *)&(iphdr->src),
(struct ip_addr *)&(iphdr->dest),
IP_PROTO_TCP, p->tot_len) != 0) {
LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packet discarded due to failing checksum 0x%04"X16_F"\n",
inet_chksum_pseudo(p, (struct ip_addr *)&(iphdr->src), (struct ip_addr *)&(iphdr->dest),
IP_PROTO_TCP, p->tot_len)));
#if TCP_DEBUG
tcp_debug_print(tcphdr);
#endif /* TCP_DEBUG */
TCP_STATS_INC(tcp.chkerr);
TCP_STATS_INC(tcp.drop);
snmp_inc_tcpinerrs();
pbuf_free(p);
return;
}
#endif
/* Move the payload pointer in the pbuf so that it points to the
TCP data instead of the TCP header. */
hdrlen = TCPH_HDRLEN(tcphdr);
if(pbuf_header(p, -(hdrlen * 4))){
/* drop short packets */
LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: short packet\n"));
TCP_STATS_INC(tcp.lenerr);
TCP_STATS_INC(tcp.drop);
snmp_inc_tcpinerrs();
pbuf_free(p);
return;
}
/* Convert fields in TCP header to host byte order. */
tcphdr->src = ntohs(tcphdr->src);
tcphdr->dest = ntohs(tcphdr->dest);
seqno = tcphdr->seqno = ntohl(tcphdr->seqno);
ackno = tcphdr->ackno = ntohl(tcphdr->ackno);
tcphdr->wnd = ntohs(tcphdr->wnd);
flags = TCPH_FLAGS(tcphdr) & TCP_FLAGS;
tcplen = p->tot_len + ((flags & TCP_FIN || flags & TCP_SYN)? 1: 0);
/* Demultiplex an incoming segment. First, we check if it is destined
for an active connection. */
prev = NULL;
for(pcb = tcp_active_pcbs; pcb != NULL; pcb = pcb->next) {
LWIP_ASSERT("tcp_input: active pcb->state != CLOSED", pcb->state != CLOSED);
LWIP_ASSERT("tcp_input: active pcb->state != TIME-WAIT", pcb->state != TIME_WAIT);
LWIP_ASSERT("tcp_input: active pcb->state != LISTEN", pcb->state != LISTEN);
if (pcb->remote_port == tcphdr->src &&
pcb->local_port == tcphdr->dest &&
ip_addr_cmp(&(pcb->remote_ip), &(iphdr->src)) &&
ip_addr_cmp(&(pcb->local_ip), &(iphdr->dest))) {
/* Move this PCB to the front of the list so that subsequent
lookups will be faster (we exploit locality in TCP segment
arrivals). */
LWIP_ASSERT("tcp_input: pcb->next != pcb (before cache)", pcb->next != pcb);
if (prev != NULL) {
prev->next = pcb->next;
pcb->next = tcp_active_pcbs;
tcp_active_pcbs = pcb;
}
LWIP_ASSERT("tcp_input: pcb->next != pcb (after cache)", pcb->next != pcb);
break;
}
prev = pcb;
}
if (pcb == NULL) {
/* If it did not go to an active connection, we check the connections
in the TIME-WAIT state. */
for(pcb = tcp_tw_pcbs; pcb != NULL; pcb = pcb->next) {
LWIP_ASSERT("tcp_input: TIME-WAIT pcb->state == TIME-WAIT", pcb->state == TIME_WAIT);
if (pcb->remote_port == tcphdr->src &&
pcb->local_port == tcphdr->dest &&
ip_addr_cmp(&(pcb->remote_ip), &(iphdr->src)) &&
ip_addr_cmp(&(pcb->local_ip), &(iphdr->dest))) {
/* We don't really care enough to move this PCB to the front
of the list since we are not very likely to receive that
many segments for connections in TIME-WAIT. */
LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packed for TIME_WAITing connection.\n"));
tcp_timewait_input(pcb);
pbuf_free(p);
return;
}
}
/* Finally, if we still did not get a match, we check all PCBs that
are LISTENing for incoming connections. */
prev = NULL;
for(lpcb = tcp_listen_pcbs.listen_pcbs; lpcb != NULL; lpcb = lpcb->next) {
if ((ip_addr_isany(&(lpcb->local_ip)) ||
ip_addr_cmp(&(lpcb->local_ip), &(iphdr->dest))) &&
lpcb->local_port == tcphdr->dest) {
/* Move this PCB to the front of the list so that subsequent
lookups will be faster (we exploit locality in TCP segment
arrivals). */
if (prev != NULL) {
((struct tcp_pcb_listen *)prev)->next = lpcb->next;
/* our successor is the remainder of the listening list */
lpcb->next = tcp_listen_pcbs.listen_pcbs;
/* put this listening pcb at the head of the listening list */
tcp_listen_pcbs.listen_pcbs = lpcb;
}
LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packed for LISTENing connection.\n"));
tcp_listen_input(lpcb);
pbuf_free(p);
return;
}
prev = (struct tcp_pcb *)lpcb;
}
}
#if TCP_INPUT_DEBUG
LWIP_DEBUGF(TCP_INPUT_DEBUG, ("+-+-+-+-+-+-+-+-+-+-+-+-+-+- tcp_input: flags "));
tcp_debug_print_flags(TCPH_FLAGS(tcphdr));
LWIP_DEBUGF(TCP_INPUT_DEBUG, ("-+-+-+-+-+-+-+-+-+-+-+-+-+-+\n"));
#endif /* TCP_INPUT_DEBUG */
if (pcb != NULL) {
/* The incoming segment belongs to a connection. */
#if TCP_INPUT_DEBUG
#if TCP_DEBUG
tcp_debug_print_state(pcb->state);
#endif /* TCP_DEBUG */
#endif /* TCP_INPUT_DEBUG */
/* Set up a tcp_seg structure. */
inseg.next = NULL;
inseg.len = p->tot_len;
inseg.dataptr = p->payload;
inseg.p = p;
inseg.tcphdr = tcphdr;
recv_data = NULL;
recv_flags = 0;
/* If there is data which was previously "refused" by upper layer */
if (pcb->refused_data != NULL) {
/* Notify again application with data previously received. */
LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: notify kept packet\n"));
TCP_EVENT_RECV(pcb, pcb->refused_data, ERR_OK, err);
if (err == ERR_OK) {
pcb->refused_data = NULL;
} else {
/* drop incoming packets, because pcb is "full" */
LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: drop incoming packets, because pcb is \"full\"\n"));
TCP_STATS_INC(tcp.drop);
snmp_inc_tcpinerrs();
pbuf_free(p);
return;
}
}
tcp_input_pcb = pcb;
err = tcp_process(pcb);
tcp_input_pcb = NULL;
/* A return value of ERR_ABRT means that tcp_abort() was called
and that the pcb has been freed. If so, we don't do anything. */
if (err != ERR_ABRT) {
if (recv_flags & TF_RESET) {
/* TF_RESET means that the connection was reset by the other
end. We then call the error callback to inform the
application that the connection is dead before we
deallocate the PCB. */
TCP_EVENT_ERR(pcb->errf, pcb->callback_arg, ERR_RST);
tcp_pcb_remove(&tcp_active_pcbs, pcb);
memp_free(MEMP_TCP_PCB, pcb);
} else if (recv_flags & TF_CLOSED) {
/* The connection has been closed and we will deallocate the
PCB. */
tcp_pcb_remove(&tcp_active_pcbs, pcb);
memp_free(MEMP_TCP_PCB, pcb);
} else {
err = ERR_OK;
/* If the application has registered a "sent" function to be
called when new send buffer space is available, we call it
now. */
if (pcb->acked > 0) {
TCP_EVENT_SENT(pcb, pcb->acked, err);
}
if (recv_data != NULL) {
if(flags & TCP_PSH) {
recv_data->flags |= PBUF_FLAG_PUSH;
}
/* Notify application that data has been received. */
TCP_EVENT_RECV(pcb, recv_data, ERR_OK, err);
/* If the upper layer can't receive this data, store it */
if (err != ERR_OK) {
pcb->refused_data = recv_data;
LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: keep incoming packet, because pcb is \"full\"\n"));
}
}
/* If a FIN segment was received, we call the callback
function with a NULL buffer to indicate EOF. */
if (recv_flags & TF_GOT_FIN) {
TCP_EVENT_RECV(pcb, NULL, ERR_OK, err);
}
/* If there were no errors, we try to send something out. */
if (err == ERR_OK) {
tcp_output(pcb);
}
}
}
/* give up our reference to inseg.p */
if (inseg.p != NULL)
{
pbuf_free(inseg.p);
inseg.p = NULL;
}
#if TCP_INPUT_DEBUG
#if TCP_DEBUG
tcp_debug_print_state(pcb->state);
#endif /* TCP_DEBUG */
#endif /* TCP_INPUT_DEBUG */
} else {
/* If no matching PCB was found, send a TCP RST (reset) to the
sender. */
LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_input: no PCB match found, resetting.\n"));
if (!(TCPH_FLAGS(tcphdr) & TCP_RST)) {
TCP_STATS_INC(tcp.proterr);
TCP_STATS_INC(tcp.drop);
tcp_rst(ackno, seqno + tcplen,
&(iphdr->dest), &(iphdr->src),
tcphdr->dest, tcphdr->src);
}
pbuf_free(p);
}
LWIP_ASSERT("tcp_input: tcp_pcbs_sane()", tcp_pcbs_sane());
PERF_STOP("tcp_input");
}
/**
* Called by tcp_input() when a segment arrives for a listening
* connection (from tcp_input()).
*
* @param pcb the tcp_pcb_listen for which a segment arrived
* @return ERR_OK if the segment was processed
* another err_t on error
*
* @note the return value is not (yet?) used in tcp_input()
* @note the segment which arrived is saved in global variables, therefore only the pcb
* involved is passed as a parameter to this function
*/
static err_t
tcp_listen_input(struct tcp_pcb_listen *pcb)
{
struct tcp_pcb *npcb;
u32_t optdata;
/* In the LISTEN state, we check for incoming SYN segments,
creates a new PCB, and responds with a SYN|ACK. */
if (flags & TCP_ACK) {
/* For incoming segments with the ACK flag set, respond with a
RST. */
LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_listen_input: ACK in LISTEN, sending reset\n"));
tcp_rst(ackno + 1, seqno + tcplen,
&(iphdr->dest), &(iphdr->src),
tcphdr->dest, tcphdr->src);
} else if (flags & TCP_SYN) {
LWIP_DEBUGF(TCP_DEBUG, ("TCP connection request %"U16_F" -> %"U16_F".\n", tcphdr->src, tcphdr->dest));
#if TCP_LISTEN_BACKLOG
if (pcb->accepts_pending >= pcb->backlog) {
return ERR_ABRT;
}
#endif /* TCP_LISTEN_BACKLOG */
npcb = tcp_alloc(pcb->prio);
/* If a new PCB could not be created (probably due to lack of memory),
we don't do anything, but rely on the sender will retransmit the
SYN at a time when we have more memory available. */
if (npcb == NULL) {
LWIP_DEBUGF(TCP_DEBUG, ("tcp_listen_input: could not allocate PCB\n"));
TCP_STATS_INC(tcp.memerr);
return ERR_MEM;
}
#if TCP_LISTEN_BACKLOG
pcb->accepts_pending++;
#endif /* TCP_LISTEN_BACKLOG */
/* Set up the new PCB. */
ip_addr_set(&(npcb->local_ip), &(iphdr->dest));
npcb->local_port = pcb->local_port;
ip_addr_set(&(npcb->remote_ip), &(iphdr->src));
npcb->remote_port = tcphdr->src;
npcb->state = SYN_RCVD;
npcb->rcv_nxt = seqno + 1;
npcb->snd_wnd = tcphdr->wnd;
npcb->ssthresh = npcb->snd_wnd;
npcb->snd_wl1 = seqno - 1;/* initialise to seqno-1 to force window update */
npcb->callback_arg = pcb->callback_arg;
#if LWIP_CALLBACK_API
npcb->accept = pcb->accept;
#endif /* LWIP_CALLBACK_API */
/* inherit socket options */
npcb->so_options = pcb->so_options & (SOF_DEBUG|SOF_DONTROUTE|SOF_KEEPALIVE|SOF_OOBINLINE|SOF_LINGER);
/* Register the new PCB so that we can begin receiving segments
for it. */
TCP_REG(&tcp_active_pcbs, npcb);
/* Parse any options in the SYN. */
tcp_parseopt(npcb);
#if TCP_CALCULATE_EFF_SEND_MSS
npcb->mss = tcp_eff_send_mss(npcb->mss, &(npcb->remote_ip));
#endif /* TCP_CALCULATE_EFF_SEND_MSS */
snmp_inc_tcppassiveopens();
/* Build an MSS option. */
optdata = TCP_BUILD_MSS_OPTION();
/* Send a SYN|ACK together with the MSS option. */
tcp_enqueue(npcb, NULL, 0, TCP_SYN | TCP_ACK, 0, (u8_t *)&optdata, 4);
return tcp_output(npcb);
}
return ERR_OK;
}
err_t tcp_enqueue (
struct tcp_pcb* pcb, void* arg, u16_t len,
u8_t flags, u8_t copy,
u8_t* optdata, u8_t optlen
) {
struct pbuf* p;
struct tcp_seg* seg, *useg, *queue;
u32_t left, seqno;
u16_t seglen;
void* ptr;
u8_t queuelen;
flags_t lPCBFlags = pcb -> flags;
int iSegCNT = 0;
left = len;
ptr = arg;
if ( len > pcb -> snd_buf ) return ERR_MEM;
seqno = pcb -> snd_lbb;
queue = NULL;
queuelen = pcb -> snd_queuelen;
if ( queuelen >= TCP_SND_QUEUELEN ) goto memerr;
seg = useg = NULL;
seglen = 0;
while ( !queue || left > 0 ) {
if ( lPCBFlags & TF_EVENSEG ) {
++iSegCNT;
seglen = left > pcb -> mss ? pcb -> mss
: (((iSegCNT%2) == 1)? ((left + 1) / 2): left);
} else seglen = left > pcb -> mss ? pcb -> mss : left;
seg = memp_malloc ( MEMP_TCP_SEG );
if ( !seg ) goto memerr;
seg -> next = NULL;
seg -> p = NULL;
if ( !queue )
useg = queue = seg;
else {
useg -> next = seg;
useg = seg;
} /* end else */
if (optdata != NULL) {
if ((seg->p = pbuf_alloc(PBUF_TRANSPORT, optlen, PBUF_RAM)) == NULL) {
goto memerr;
}
++queuelen;
seg->dataptr = seg->p->payload;
}
else if (copy) {
if ((seg->p = pbuf_alloc(PBUF_TRANSPORT, seglen, PBUF_RAM)) == NULL) {
LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_enqueue : could not allocate memory for pbuf copy size %u\n", seglen));
goto memerr;
}
++queuelen;
if (arg != NULL) {
mips_memcpy(seg->p->payload, ptr, seglen);
}
seg->dataptr = seg->p->payload;
}
/* do not copy data */
else {
/* 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.
*/
if ((p = pbuf_alloc(PBUF_TRANSPORT, seglen, PBUF_ROM)) == NULL) {
LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_enqueue: could not allocate memory for zero-copy pbuf\n"));
goto memerr;
}
++queuelen;
p->payload = ptr;
seg->dataptr = ptr;
/* Second, allocate a pbuf for the headers. */
if ((seg->p = pbuf_alloc(PBUF_TRANSPORT, 0, PBUF_RAM)) == NULL) {
/* If allocation fails, we have to deallocate the data pbuf as
* well. */
pbuf_free(p);
LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_enqueue: could not allocate memory for header pbuf\n"));
goto memerr;
}
++queuelen;
/* Concatenate the headers and data pbufs together. */
pbuf_cat(seg->p, p);
p = NULL;
}
/* Now that there are more segments queued, we check again if the
length of the queue exceeds the configured maximum. */
if (queuelen > TCP_SND_QUEUELEN) {
LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_enqueue: queue too long %u (%u)\n", queuelen, TCP_SND_QUEUELEN));
goto memerr;
}
seg->len = seglen;
if (pbuf_header(seg->p, TCP_HLEN)) {
LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_enqueue: no room for TCP header in pbuf.\n"));
TCP_STATS_INC(tcp.err);
goto memerr;
}
seg->tcphdr = seg->p->payload;
seg->tcphdr->src = htons(pcb->local_port);
seg->tcphdr->dest = htons(pcb->remote_port);
seg->tcphdr->seqno = htonl(seqno);
seg->tcphdr->urgp = 0;
TCPH_FLAGS_SET(seg->tcphdr, flags);
/* don't fill in tcphdr->ackno and tcphdr->wnd until later */
/* Copy the options into the header, if they are present. */
if (optdata == NULL) {
TCPH_HDRLEN_SET(seg->tcphdr, 5);
}
else {
TCPH_HDRLEN_SET(seg->tcphdr, (5 + optlen / 4));
/* Copy options into data portion of segment.
Options can thus only be sent in non data carrying
segments such as SYN|ACK. */
mips_memcpy(seg->dataptr, optdata, optlen);
}
left -= seglen;
seqno += seglen;
ptr = (void *)((char *)ptr + seglen);
}
/* Now that the data to be enqueued has been broken up into TCP
segments in the queue variable, we add them to the end of the
pcb->unsent queue. */
if (pcb->unsent == NULL) {
useg = NULL;
}
else {
for (useg = pcb->unsent; useg->next != NULL; useg = useg->next);
}
/* If there is room in the last pbuf on the unsent queue,
chain the first pbuf on the queue together with that. */
if (useg != NULL &&
TCP_TCPLEN(useg) != 0 &&
!(TCPH_FLAGS(useg->tcphdr) & (TCP_SYN | TCP_FIN)) &&
!(flags & (TCP_SYN | TCP_FIN)) &&
useg->len + queue->len <= pcb->mss) {
/* Remove TCP header from first segment. */
pbuf_header(queue->p, -TCP_HLEN);
pbuf_cat(useg->p, queue->p);
useg->len += queue->len;
useg->next = queue->next;
if (seg == queue) seg = NULL;
memp_free(MEMP_TCP_SEG, queue);
}
else {
if (useg == NULL) {
pcb->unsent = queue;
}
else {
useg->next = queue;
}
}
if ((flags & TCP_SYN) || (flags & TCP_FIN)) {
++len;
}
pcb->snd_lbb += len;
pcb->snd_buf -= len;
pcb->snd_queuelen = queuelen;
LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_enqueue: %d (after enqueued)\n", pcb->snd_queuelen));
if (pcb->snd_queuelen != 0) {
LWIP_ASSERT("tcp_enqueue: valid queue length", pcb->unacked != NULL ||
pcb->unsent != NULL);
}
/* Set the PSH flag in the last segment that we enqueued, but only
if the segment has data (indicated by seglen > 0). */
if (seg != NULL && seglen > 0 && seg->tcphdr != NULL) {
TCPH_SET_FLAG(seg->tcphdr, TCP_PSH);
}
return ERR_OK;
memerr:
TCP_STATS_INC(tcp.memerr);
if (queue != NULL) {
tcp_segs_free(queue);
}
if (pcb->snd_queuelen != 0) {
LWIP_ASSERT("tcp_enqueue: valid queue length", pcb->unacked != NULL ||
pcb->unsent != NULL);
}
LWIP_DEBUGF(TCP_QLEN_DEBUG | DBG_STATE, ("tcp_enqueue: %d (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 (FIN flag should always come through!)*/
if (((pcb->snd_queuelen >= pcb->max_unsent_len) || (pcb->snd_queuelen > TCP_SNDQUEUELEN_OVERFLOW)) &&
((flags & TCP_FIN) == 0)) {
LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 3, ("tcp_enqueue_flags: too long queue %"U16_F" (max %"U16_F")\n",
pcb->snd_queuelen, pcb->max_unsent_len));
TCP_STATS_INC(tcp.memerr);
pcb->flags |= TF_NAGLEMEMERR;
return ERR_MEM;
}
if (flags & TCP_SYN) {
optflags = TF_SEG_OPTS_MSS;
if(enable_wnd_scale) optflags |= TF_SEG_OPTS_WNDSCALE;
#if LWIP_TCP_TIMESTAMPS
if (pcb->enable_ts_opt && !(flags & TCP_ACK)) {
// enable initial timestamp announcement only for the connecting side. accepting side reply accordingly.
optflags |= TF_SEG_OPTS_TS;
}
#endif
}
#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;
}*/ //to consider snd_buf for syn or fin, unmarked sections with SND_BUF_FOR_SYN_FIN
/* Allocate pbuf with room for TCP header + options */
if ((p = tcp_tx_pbuf_alloc(pcb, 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("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--; SND_BUF_FOR_SYN_FIN
}
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;
}
/**
* 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 LWIP_3RD_PARTY_BUFS
if ((seg = external_tcp_seg_alloc(pcb)) == NULL) {
#else
if ((seg = (struct tcp_seg *)memp_malloc(MEMP_TCP_SEG)) == NULL) {
#endif
LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_create_segment: no memory.\n"));
tcp_tx_pbuf_free(pcb, p);
return NULL;
}
seg->flags = optflags;
seg->next = NULL;
seg->p = p;
seg->dataptr = p->payload;
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 */
seg->seqno = seqno;
/* 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_tx_seg_free(pcb, 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
*/
static struct pbuf *
tcp_pbuf_prealloc(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 (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 + pcb->tcp_oversize_val));
}
}
p = tcp_tx_pbuf_alloc(pcb, 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;
}
/** 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, u32_t len)
{
/* connection is in invalid state for data transmission? */
if ((get_tcp_state(pcb) != ESTABLISHED) &&
(get_tcp_state(pcb) != CLOSE_WAIT) &&
(get_tcp_state(pcb) != SYN_SENT) &&
(get_tcp_state(pcb) != 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=%"U32_F" > snd_buf=%"U32_F")\n",
len, pcb->snd_buf));
pcb->flags |= TF_NAGLEMEMERR;
return ERR_MEM;
}
LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_write: queuelen: %"U32_F"\n", (u32_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 >= pcb->max_unsent_len) || (pcb->snd_queuelen > TCP_SNDQUEUELEN_OVERFLOW)) {
LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 3, ("tcp_write: too long queue %"U32_F" (max %"U32_F")\n",
pcb->snd_queuelen, pcb->max_unsent_len));
TCP_STATS_INC(tcp.memerr);
pcb->flags |= TF_NAGLEMEMERR;
return ERR_MEM;
}
if (pcb->snd_queuelen != 0) {
} 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, u32_t len, u8_t apiflags)
{
struct pbuf *concat_p = NULL;
struct tcp_seg *seg = NULL, *prev_seg = NULL, *queue = NULL;
u32_t pos = 0; /* position in 'arg' data */
u32_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);
mss_local = mss_local ? mss_local : pcb->mss;
int byte_queued = pcb->snd_nxt - pcb->lastack;
if ( len < pcb->mss)
pcb->snd_sml_add = (pcb->unacked ? pcb->unacked->len : 0) + byte_queued;
#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;
/* ensure that segments can hold at least one data byte... */
mss_local = LWIP_MAX(mss_local, LWIP_TCP_OPT_LEN_TS + 1);
}
#endif /* LWIP_TCP_TIMESTAMPS */
optlen = LWIP_TCP_OPT_LENGTH( optflags );
/*
* 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;
if (!pcb->last_unsent || pcb->last_unsent->next) {
/* @todo: this could be sped up by keeping last_unsent in the pcb */
for (pcb->last_unsent = pcb->unsent; pcb->last_unsent->next != NULL;
pcb->last_unsent = pcb->last_unsent->next);
}
/* Usable space at the end of the last unsent segment */
unsent_optlen = LWIP_TCP_OPT_LENGTH(pcb->last_unsent->flags);
LWIP_ASSERT("mss_local is too small", mss_local >= pcb->last_unsent->len + unsent_optlen);
space = mss_local - (pcb->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 == pcb->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 = pcb->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) && (pcb->last_unsent->len > 0)) {
u16_t seglen = space < len - pos ? space : len - pos;
seg = pcb->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(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
pcb->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 {
LWIP_ASSERT("tcp_write : we are never here", 0);
goto memerr;
}
pos += seglen;
queuelen += pbuf_clen(concat_p);
}
} else {
#if TCP_OVERSIZE
pcb->last_unsent = NULL;
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;
u32_t left = len - pos;
u16_t max_len = mss_local - optlen;
u16_t seglen = left > max_len ? max_len : left;
if (apiflags & TCP_WRITE_FLAG_COPY) {
/* If copy is set, memory should be allocated and data copied
* into pbuf */
if ((p = tcp_pbuf_prealloc(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 {
LWIP_ASSERT("tcp_write: we are never here",0);
goto memerr;
}
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 > pcb->max_unsent_len) || (queuelen > TCP_SNDQUEUELEN_OVERFLOW)) {
LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_write: queue too long %"U32_F" (%"U32_F")\n", queuelen, pcb->max_unsent_len));
tcp_tx_pbuf_free(pcb, 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 */
/* Fix dataptr for the nocopy case */
if ((apiflags & TCP_WRITE_FLAG_COPY) == 0) {
seg->dataptr = (u8_t*)arg + pos;
}
/* 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 = pcb->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, pcb->last_unsent);
p->len += oversize_used;
}
}
pcb->last_unsent->len += oversize_used;
#if TCP_OVERSIZE_DBGCHECK
pcb->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 pcb->last_unsent->p
*/
if (concat_p != NULL) {
LWIP_ASSERT("tcp_write: cannot concatenate when pcb->unsent is empty",
(pcb->last_unsent != NULL));
pbuf_cat(pcb->last_unsent->p, concat_p);
pcb->last_unsent->len += concat_p->tot_len;
#if TCP_CHECKSUM_ON_COPY
if (concat_chksummed) {
tcp_seg_add_chksum(concat_chksum, concat_chksummed, &pcb->last_unsent->chksum,
&pcb->last_unsent->chksum_swapped);
pcb->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 (pcb->last_unsent == NULL) {
pcb->unsent = queue;
} else {
pcb->last_unsent->next = queue;
}
pcb->last_unsent = seg;
/*
* 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) {
TCPH_SET_FLAG(seg->tcphdr, TCP_PSH);
}
return ERR_OK;
memerr:
pcb->flags |= TF_NAGLEMEMERR;
TCP_STATS_INC(tcp.memerr);
if (concat_p != NULL) {
tcp_tx_pbuf_free(pcb, concat_p);
}
if (queue != NULL) {
tcp_tx_segs_free(pcb, 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;
}
/**
* Send persist timer zero-window probes to keep a connection active
* when a window update is lost.
*
* Called by tcp_slowtmr()
*
* @param pcb the tcp_pcb for which to send a zero-window probe packet
*/
void
tcp_zero_window_probe(struct tcp_pcb *pcb)
{
struct pbuf *p;
struct tcp_hdr *tcphdr;
struct tcp_seg *seg;
u16_t len;
u8_t is_fin;
LWIP_DEBUGF(TCP_DEBUG,
("tcp_zero_window_probe: sending ZERO WINDOW probe to %"
U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
ip4_addr1_16(&pcb->remote_ip), ip4_addr2_16(&pcb->remote_ip),
ip4_addr3_16(&pcb->remote_ip), ip4_addr4_16(&pcb->remote_ip)));
LWIP_DEBUGF(TCP_DEBUG,
("tcp_zero_window_probe: tcp_ticks %"U32_F
" pcb->tmr %"U32_F" pcb->keep_cnt_sent %"U16_F"\n",
tcp_ticks, pcb->tmr, pcb->keep_cnt_sent));
seg = pcb->unacked;
if(seg == NULL) {
seg = pcb->unsent;
}
if(seg == NULL) {
return;
}
is_fin = ((TCPH_FLAGS(seg->tcphdr) & TCP_FIN) != 0) && (seg->len == 0);
/* 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 *)p->payload + TCP_HLEN) = *(char *)seg->dataptr;
}
#if CHECKSUM_GEN_TCP
tcphdr->chksum = inet_chksum_pseudo(p, &pcb->local_ip, &pcb->remote_ip,
IP_PROTO_TCP, (u16_t)p->tot_len);
#endif
TCP_STATS_INC(tcp.xmit);
/* Send output to IP */
#if LWIP_NETIF_HWADDRHINT
ip_output_hinted(p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl, 0, IP_PROTO_TCP,
&(pcb->addr_hint));
#elif LWIP_3RD_PARTY_L3
pcb->ip_output(p, pcb, 0);
#else /* LWIP_NETIF_HWADDRHINT*/
ip_output(p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl, 0, IP_PROTO_TCP);
#endif /* LWIP_NETIF_HWADDRHINT*/
tcp_tx_pbuf_free(pcb, p);
LWIP_DEBUGF(TCP_DEBUG, ("tcp_zero_window_probe: seqno %"U32_F
" ackno %"U32_F".\n",
pcb->snd_nxt - 1, pcb->rcv_nxt));
}
/**
* 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;
/* 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 = RCV_WND_SCALE(pcb, pcb->rcv_ann_wnd); // Which means: htons(pcb->rcv_ann_wnd >> pcb->rcv_scale);
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 */
LWIP_ASSERT("seg->tcphdr not aligned", ((mem_ptr_t)(seg->tcphdr + 1) % 4) == 0);
opts = (u32_t *)(void *)(seg->tcphdr + 1);
if (seg->flags & TF_SEG_OPTS_MSS) {
TCP_BUILD_MSS_OPTION(*opts, pcb->advtsd_mss);
opts += 1; // Move to the next line (meaning next 32 bit) as this option is 4 bytes long
}
/* If RCV_SCALE is set then prepare segment for window scaling option */
if (seg->flags & TF_SEG_OPTS_WNDSCALE) {
TCP_BUILD_WNDSCALE_OPTION(*opts, pcb->rcv_scale);
opts += 1; // Move to the next line (meaning next 32 bit) as this option is 3 bytes long + we added 1 byte NOOP padding => total 4 bytes
}
#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; // Move to the next line (meaning next 32 bit) as this option is 10 bytes long, 12 with padding (so jump 3 lines)
}
#endif
/* If we don't have a local IP address, we get one by
calling ip_route(). */
if (ip_addr_isany(&(pcb->local_ip))) {
LWIP_ASSERT("tcp_output_segment: need to find route to host", 0);
}
/* Set retransmission timer running if it is not currently enabled */
if(pcb->rtime == -1) {
pcb->rtime = 0;
}
if (pcb->rttest == 0) {
pcb->rttest = tcp_ticks;
pcb->rtseq = seg->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;
TCP_STATS_INC(tcp.xmit);
#if LWIP_NETIF_HWADDRHINT
ip_output_hinted(seg->p, &(pcb->local_ip), &(pcb->remote_ip), pcb->ttl, pcb->tos,
IP_PROTO_TCP, &(pcb->addr_hint));
#elif LWIP_3RD_PARTY_L3
pcb->ip_output(seg->p, pcb, seg->seqno < pcb->snd_nxt);
#else /* LWIP_NETIF_HWADDRHINT*/
ip_output(seg->p, &(pcb->local_ip), &(pcb->remote_ip), pcb->ttl, pcb->tos, IP_PROTO_TCP);
#endif /* LWIP_NETIF_HWADDRHINT*/
}