void
tcp_slowtmr(void)
{
struct tcp_pcb *pcb, *pcb2, *prev;
u32_t eff_wnd;
u8_t pcb_remove; /* flag if a PCB should be removed */
err_t err;
err = ERR_OK;
++tcp_ticks;
/* Steps through all of the active PCBs. */
prev = NULL;
pcb = tcp_active_pcbs;
if (pcb == NULL) LWIP_DEBUGF(TCP_DEBUG, ("tcp_slowtmr: no active pcbs\n"));
while (pcb != NULL) {
LWIP_DEBUGF(TCP_DEBUG, ("tcp_slowtmr: processing active pcb\n"));
LWIP_ASSERT("tcp_slowtmr: active pcb->state != CLOSED\n", pcb->state != CLOSED);
LWIP_ASSERT("tcp_slowtmr: active pcb->state != LISTEN\n", pcb->state != LISTEN);
LWIP_ASSERT("tcp_slowtmr: active pcb->state != TIME-WAIT\n", pcb->state != TIME_WAIT);
pcb_remove = 0;
if (pcb->state == SYN_SENT && pcb->nrtx == TCP_SYNMAXRTX) {
++pcb_remove;
LWIP_DEBUGF(TCP_DEBUG, ("tcp_slowtmr: max SYN retries reached\n"));
}
else if (pcb->nrtx == TCP_MAXRTX) {
++pcb_remove;
LWIP_DEBUGF(TCP_DEBUG, ("tcp_slowtmr: max DATA retries reached\n"));
} else {
++pcb->rtime;
if (pcb->unacked != NULL && pcb->rtime >= pcb->rto) {
/* Time for a retransmission. */
LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_slowtmr: rtime %u pcb->rto %u\n",
pcb->rtime, pcb->rto));
/* Double retransmission time-out unless we are trying to
* connect to somebody (i.e., we are in SYN_SENT). */
if (pcb->state != SYN_SENT) {
pcb->rto = ((pcb->sa >> 3) + pcb->sv) << tcp_backoff[pcb->nrtx];
}
tcp_rexmit(pcb);
/* Reduce congestion window and ssthresh. */
eff_wnd = LWIP_MIN(pcb->cwnd, pcb->snd_wnd);
pcb->ssthresh = eff_wnd >> 1;
if (pcb->ssthresh < pcb->mss) {
pcb->ssthresh = pcb->mss * 2;
}
pcb->cwnd = pcb->mss;
LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_slowtmr: cwnd %u ssthresh %u\n",
pcb->cwnd, pcb->ssthresh));
}
}
/**
* Handle retransmission after three dupacks received
*
* @param pcb the tcp_pcb for which to retransmit the first unacked segment
*/
void
tcp_rexmit_fast(struct tcp_pcb *pcb)
{
if (pcb->unacked != NULL && !(pcb->flags & TF_INFR)) {
/* This is fast retransmit. Retransmit the first unacked segment. */
LWIP_DEBUGF(TCP_FR_DEBUG,
("tcp_receive: dupacks %"U16_F" (%"U32_F
"), fast retransmit %"U32_F"\n",
(u16_t)pcb->dupacks, pcb->lastack,
pcb->unacked->seqno));
tcp_rexmit(pcb);
#if TCP_CC_ALGO_MOD
cc_cong_signal(pcb, CC_NDUPACK);
#else
/* Set ssthresh to half of the minimum of the current
* cwnd and the advertised window */
if (pcb->cwnd > pcb->snd_wnd) {
pcb->ssthresh = pcb->snd_wnd / 2;
} else {
pcb->ssthresh = pcb->cwnd / 2;
}
/* The minimum value for ssthresh should be 2 MSS */
if (pcb->ssthresh < (2U * pcb->mss)) {
LWIP_DEBUGF(TCP_FR_DEBUG,
("tcp_receive: The minimum value for ssthresh %"U16_F
" should be min 2 mss %"U16_F"...\n",
pcb->ssthresh, 2*pcb->mss));
pcb->ssthresh = 2*pcb->mss;
}
pcb->cwnd = pcb->ssthresh + 3 * pcb->mss;
#endif
pcb->flags |= TF_INFR;
}
}
void tcp_appsend(FAR struct net_driver_s *dev, FAR struct tcp_conn_s *conn,
uint16_t result)
{
uint8_t hdrlen;
/* Handle the result based on the application response */
nllvdbg("result: %04x d_sndlen: %d conn->unacked: %d\n",
result, dev->d_sndlen, conn->unacked);
/* Get the IP header length associated with the IP domain configured for
* this TCP connection.
*/
#ifdef CONFIG_NET_IPv4
#ifdef CONFIG_NET_IPv6
if (conn->domain == PF_INET)
#endif
{
DEBUGASSERT(IFF_IS_IPv4(dev->d_flags));
hdrlen = IPv4TCP_HDRLEN;
}
#endif /* CONFIG_NET_IPv4 */
#ifdef CONFIG_NET_IPv6
#ifdef CONFIG_NET_IPv4
else
#endif
{
DEBUGASSERT(IFF_IS_IPv6(dev->d_flags));
hdrlen = IPv6TCP_HDRLEN;
}
#endif /* CONFIG_NET_IPv6 */
/* Check for connection aborted */
if ((result & TCP_ABORT) != 0)
{
dev->d_sndlen = 0;
conn->tcpstateflags = TCP_CLOSED;
nllvdbg("TCP state: TCP_CLOSED\n");
tcp_send(dev, conn, TCP_RST | TCP_ACK, hdrlen);
}
/* Check for connection closed */
else if ((result & TCP_CLOSE) != 0)
{
conn->tcpstateflags = TCP_FIN_WAIT_1;
conn->unacked = 1;
conn->nrtx = 0;
nllvdbg("TCP state: TCP_FIN_WAIT_1\n");
dev->d_sndlen = 0;
tcp_send(dev, conn, TCP_FIN | TCP_ACK, hdrlen);
}
/* None of the above */
else
{
#ifdef CONFIG_NET_TCP_WRITE_BUFFERS
DEBUGASSERT(dev->d_sndlen >= 0 && dev->d_sndlen <= conn->mss);
#else
/* If d_sndlen > 0, the application has data to be sent. */
if (dev->d_sndlen > 0)
{
/* Remember how much data we send out now so that we know
* when everything has been acknowledged. Just increment the amount
* of data sent. This will be needed in sequence number calculations
* and we know that this is not a re-transmission. Retransmissions
* do not go through this path.
*/
conn->unacked += dev->d_sndlen;
/* The application cannot send more than what is allowed by the
* MSS (the minumum of the MSS and the available window).
*/
DEBUGASSERT(dev->d_sndlen <= conn->mss);
}
conn->nrtx = 0;
#endif
/* Then handle the rest of the operation just as for the rexmit case */
tcp_rexmit(dev, conn, result);
}
}
/**
* Called by tcp_process. Checks if the given segment is an ACK for outstanding
* data, and if so frees the memory of the buffered data. Next, is places the
* segment on any of the receive queues (pcb->recved or pcb->ooseq). If the segment
* is buffered, the pbuf is referenced by pbuf_ref so that it will not be freed until
* i it has been removed from the buffer.
*
* If the incoming segment constitutes an ACK for a segment that was used for RTT
* estimation, the RTT is estimated here as well.
*
* Called from tcp_process().
*
* @return 1 if the incoming segment is the next in sequence, 0 if not
*/
static u8_t
tcp_receive(struct tcp_pcb *pcb)
{
struct tcp_seg *next;
#if TCP_QUEUE_OOSEQ
struct tcp_seg *prev, *cseg;
#endif
struct pbuf *p;
s32_t off;
s16_t m;
u32_t right_wnd_edge;
u16_t new_tot_len;
u8_t accepted_inseq = 0;
if (flags & TCP_ACK) {
right_wnd_edge = pcb->snd_wnd + pcb->snd_wl1;
/* Update window. */
if (TCP_SEQ_LT(pcb->snd_wl1, seqno) ||
(pcb->snd_wl1 == seqno && TCP_SEQ_LT(pcb->snd_wl2, ackno)) ||
(pcb->snd_wl2 == ackno && tcphdr->wnd > pcb->snd_wnd)) {
pcb->snd_wnd = tcphdr->wnd;
pcb->snd_wl1 = seqno;
pcb->snd_wl2 = ackno;
if (pcb->snd_wnd > 0 && pcb->persist_backoff > 0) {
pcb->persist_backoff = 0;
}
LWIP_DEBUGF(TCP_WND_DEBUG, ("tcp_receive: window update %"U16_F"\n", pcb->snd_wnd));
#if TCP_WND_DEBUG
} else {
if (pcb->snd_wnd != tcphdr->wnd) {
LWIP_DEBUGF(TCP_WND_DEBUG, ("tcp_receive: no window update lastack %"U32_F" snd_max %"U32_F" ackno %"U32_F" wl1 %"U32_F" seqno %"U32_F" wl2 %"U32_F"\n",
pcb->lastack, pcb->snd_max, ackno, pcb->snd_wl1, seqno, pcb->snd_wl2));
}
#endif /* TCP_WND_DEBUG */
}
if (pcb->lastack == ackno) {
pcb->acked = 0;
if (pcb->snd_wl1 + pcb->snd_wnd == right_wnd_edge){
++pcb->dupacks;
if (pcb->dupacks >= 3 && pcb->unacked != NULL) {
if (!(pcb->flags & TF_INFR)) {
/* This is fast retransmit. Retransmit the first unacked segment. */
LWIP_DEBUGF(TCP_FR_DEBUG, ("tcp_receive: dupacks %"U16_F" (%"U32_F"), fast retransmit %"U32_F"\n",
(u16_t)pcb->dupacks, pcb->lastack,
ntohl(pcb->unacked->tcphdr->seqno)));
tcp_rexmit(pcb);
/* Set ssthresh to max (FlightSize / 2, 2*SMSS) */
/*pcb->ssthresh = LWIP_MAX((pcb->snd_max -
pcb->lastack) / 2,
2 * pcb->mss);*/
/* Set ssthresh to half of the minimum of the current cwnd and the advertised window */
if (pcb->cwnd > pcb->snd_wnd)
pcb->ssthresh = pcb->snd_wnd / 2;
else
pcb->ssthresh = pcb->cwnd / 2;
/* The minimum value for ssthresh should be 2 MSS */
if (pcb->ssthresh < 2*pcb->mss) {
LWIP_DEBUGF(TCP_FR_DEBUG, ("tcp_receive: The minimum value for ssthresh %"U16_F" should be min 2 mss %"U16_F"...\n", pcb->ssthresh, 2*pcb->mss));
pcb->ssthresh = 2*pcb->mss;
}
pcb->cwnd = pcb->ssthresh + 3 * pcb->mss;
pcb->flags |= TF_INFR;
} else {
/* Inflate the congestion window, but not if it means that
the value overflows. */
if ((u16_t)(pcb->cwnd + pcb->mss) > pcb->cwnd) {
pcb->cwnd += pcb->mss;
}
}
}
} else {
LWIP_DEBUGF(TCP_FR_DEBUG, ("tcp_receive: dupack averted %"U32_F" %"U32_F"\n",
pcb->snd_wl1 + pcb->snd_wnd, right_wnd_edge));
}
} else if (TCP_SEQ_BETWEEN(ackno, pcb->lastack+1, pcb->snd_max)){
/* We come here when the ACK acknowledges new data. */
/* Reset the "IN Fast Retransmit" flag, since we are no longer
in fast retransmit. Also reset the congestion window to the
slow start threshold. */
if (pcb->flags & TF_INFR) {
pcb->flags &= ~TF_INFR;
pcb->cwnd = pcb->ssthresh;
}
/* Reset the number of retransmissions. */
pcb->nrtx = 0;
/* Reset the retransmission time-out. */
pcb->rto = (pcb->sa >> 3) + pcb->sv;
/* Update the send buffer space. Diff between the two can never exceed 64K? */
pcb->acked = (u16_t)(ackno - pcb->lastack);
pcb->snd_buf += pcb->acked;
/* Reset the fast retransmit variables. */
pcb->dupacks = 0;
pcb->lastack = ackno;
/* Update the congestion control variables (cwnd and
ssthresh). */
if (pcb->state >= ESTABLISHED) {
if (pcb->cwnd < pcb->ssthresh) {
if ((u16_t)(pcb->cwnd + pcb->mss) > pcb->cwnd) {
pcb->cwnd += pcb->mss;
}
LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_receive: slow start cwnd %"U16_F"\n", pcb->cwnd));
} else {
u16_t new_cwnd = (pcb->cwnd + pcb->mss * pcb->mss / pcb->cwnd);
if (new_cwnd > pcb->cwnd) {
pcb->cwnd = new_cwnd;
}
LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_receive: congestion avoidance cwnd %"U16_F"\n", pcb->cwnd));
}
}
LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: ACK for %"U32_F", unacked->seqno %"U32_F":%"U32_F"\n",
ackno,
pcb->unacked != NULL?
ntohl(pcb->unacked->tcphdr->seqno): 0,
pcb->unacked != NULL?
ntohl(pcb->unacked->tcphdr->seqno) + TCP_TCPLEN(pcb->unacked): 0));
/* Remove segment from the unacknowledged list if the incoming
ACK acknowlegdes them. */
while (pcb->unacked != NULL &&
TCP_SEQ_LEQ(ntohl(pcb->unacked->tcphdr->seqno) +
TCP_TCPLEN(pcb->unacked), ackno)) {
LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: removing %"U32_F":%"U32_F" from pcb->unacked\n",
ntohl(pcb->unacked->tcphdr->seqno),
ntohl(pcb->unacked->tcphdr->seqno) +
TCP_TCPLEN(pcb->unacked)));
next = pcb->unacked;
pcb->unacked = pcb->unacked->next;
LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_receive: queuelen %"U16_F" ... ", (u16_t)pcb->snd_queuelen));
LWIP_ASSERT("pcb->snd_queuelen >= pbuf_clen(next->p)", (pcb->snd_queuelen >= pbuf_clen(next->p)));
pcb->snd_queuelen -= pbuf_clen(next->p);
tcp_seg_free(next);
LWIP_DEBUGF(TCP_QLEN_DEBUG, ("%"U16_F" (after freeing unacked)\n", (u16_t)pcb->snd_queuelen));
if (pcb->snd_queuelen != 0) {
LWIP_ASSERT("tcp_receive: valid queue length", pcb->unacked != NULL ||
pcb->unsent != NULL);
}
}
/* If there's nothing left to acknowledge, stop the retransmit
timer, otherwise reset it to start again */
if(pcb->unacked == NULL)
pcb->rtime = -1;
else
pcb->rtime = 0;
pcb->polltmr = 0;
} else {
void tcp_timer(FAR struct net_driver_s *dev, FAR struct tcp_conn_s *conn,
int hsec)
{
uint16_t result;
uint8_t hdrlen;
/* Set up for the callback. We can't know in advance if the application
* is going to send a IPv4 or an IPv6 packet, so this setup may not
* actually be used. Furthermore, the TCP logic is required to call
* tcp_ipv4_select() or tcp_ipv6_select() prior to sending any packets.
* We will try to set the correct value here basic on the binding of
* the connection.
*/
#ifdef CONFIG_NET_IPv4
#ifdef CONFIG_NET_IPv6
if (conn->domain == PF_INET)
#endif
{
hdrlen = IPv4TCP_HDRLEN;
tcp_ipv4_select(dev);
}
#endif /* CONFIG_NET_IPv4 */
#ifdef CONFIG_NET_IPv6
#ifdef CONFIG_NET_IPv4
else
#endif
{
hdrlen = IPv6TCP_HDRLEN;
tcp_ipv6_select(dev);
}
#endif /* CONFIG_NET_IPv6 */
/* Increase the TCP sequence number */
tcp_nextsequence();
/* Reset the length variables. */
dev->d_len = 0;
dev->d_sndlen = 0;
/* Check if the connection is in a state in which we simply wait
* for the connection to time out. If so, we increase the
* connection's timer and remove the connection if it times
* out.
*/
if (conn->tcpstateflags == TCP_TIME_WAIT ||
conn->tcpstateflags == TCP_FIN_WAIT_2)
{
unsigned int newtimer;
/* Increment the connection timer */
newtimer = (unsigned int)conn->timer + hsec;
/* Check if the timer exceeds the timeout value */
if (newtimer >= TCP_TIME_WAIT_TIMEOUT)
{
/* Set the timer to the maximum value */
conn->timer = TCP_TIME_WAIT_TIMEOUT;
/* The TCP connection was established and, hence, should be bound
* to a device. Make sure that the polling device is the one that
* we are bound to.
*
* If not, then we will catch the timeout on the next poll from
* the correct device.
*/
DEBUGASSERT(conn->dev != NULL);
if (dev != conn->dev)
{
ninfo("TCP: TCP_CLOSED pending\n");
}
else
{
conn->tcpstateflags = TCP_CLOSED;
/* Notify upper layers about the timeout */
result = tcp_callback(dev, conn, TCP_TIMEDOUT);
ninfo("TCP state: TCP_CLOSED\n");
}
}
else
{
/* No timeout. Just update the incremented timer */
conn->timer = newtimer;
}
}
else if (conn->tcpstateflags != TCP_CLOSED)
{
/* If the connection has outstanding data, we increase the connection's
* timer and see if it has reached the RTO value in which case we
* retransmit.
*/
if (conn->unacked > 0)
{
/* The connection has outstanding data */
if (conn->timer > hsec)
{
/* Will not yet decrement to zero */
conn->timer -= hsec;
}
else
{
/* Will decrement to zero */
conn->timer = 0;
/* The TCP is connected and, hence, should be bound to a
* device. Make sure that the polling device is the one that
* we are bound to.
*
* If not, then we will catch the timeout on the next poll
* from the correct device.
*/
DEBUGASSERT(conn->dev != NULL);
if (dev != conn->dev)
{
ninfo("TCP: TCP_CLOSED pending\n");
goto done;
}
/* Check for a timeout on connection in the TCP_SYN_RCVD state.
* On such timeouts, we would normally resend the SYNACK until
* the ACK is received, completing the 3-way handshake. But if
* the retry count elapsed, then we must assume that no ACK is
* forthcoming and terminate the attempted connection.
*/
if (conn->tcpstateflags == TCP_SYN_RCVD &&
conn->nrtx >= TCP_MAXSYNRTX)
{
FAR struct tcp_conn_s *listener;
conn->tcpstateflags = TCP_CLOSED;
ninfo("TCP state: TCP_SYN_RCVD->TCP_CLOSED\n");
/* Find the listener for this connection. */
#if defined(CONFIG_NET_IPv4) && defined(CONFIG_NET_IPv6)
listener = tcp_findlistener(conn->lport, conn->domain);
#else
listener = tcp_findlistener(conn->lport);
#endif
if (listener != NULL)
{
/* We call tcp_callback() for the connection with
* TCP_TIMEDOUT to inform the listener that the
* connection has timed out.
*/
result = tcp_callback(dev, listener, TCP_TIMEDOUT);
}
/* We also send a reset packet to the remote host. */
tcp_send(dev, conn, TCP_RST | TCP_ACK, hdrlen);
/* Finally, we must free this TCP connection structure */
tcp_free(conn);
goto done;
}
/* Otherwise, check for a timeout on an established connection.
* If the retry count is exceeded in this case, we should
* close the connection.
*/
else if (
#ifdef CONFIG_NET_TCP_WRITE_BUFFERS
conn->expired > 0 ||
#else
conn->nrtx >= TCP_MAXRTX ||
#endif
(conn->tcpstateflags == TCP_SYN_SENT &&
conn->nrtx >= TCP_MAXSYNRTX)
)
{
conn->tcpstateflags = TCP_CLOSED;
ninfo("TCP state: TCP_CLOSED\n");
/* We call tcp_callback() with TCP_TIMEDOUT to
* inform the application that the connection has
* timed out.
*/
result = tcp_callback(dev, conn, TCP_TIMEDOUT);
/* We also send a reset packet to the remote host. */
tcp_send(dev, conn, TCP_RST | TCP_ACK, hdrlen);
goto done;
}
/* Exponential backoff. */
conn->timer = TCP_RTO << (conn->nrtx > 4 ? 4: conn->nrtx);
(conn->nrtx)++;
/* Ok, so we need to retransmit. We do this differently
* depending on which state we are in. In ESTABLISHED, we
* call upon the application so that it may prepare the
* data for the retransmit. In SYN_RCVD, we resend the
* SYNACK that we sent earlier and in LAST_ACK we have to
* retransmit our FINACK.
*/
#ifdef CONFIG_NET_STATISTICS
g_netstats.tcp.rexmit++;
#endif
switch (conn->tcpstateflags & TCP_STATE_MASK)
{
case TCP_SYN_RCVD:
/* In the SYN_RCVD state, we should retransmit our
* SYNACK.
*/
tcp_ack(dev, conn, TCP_ACK | TCP_SYN);
goto done;
case TCP_SYN_SENT:
/* In the SYN_SENT state, we retransmit out SYN. */
tcp_ack(dev, conn, TCP_SYN);
goto done;
case TCP_ESTABLISHED:
/* In the ESTABLISHED state, we call upon the application
* to do the actual retransmit after which we jump into
* the code for sending out the packet.
*/
result = tcp_callback(dev, conn, TCP_REXMIT);
tcp_rexmit(dev, conn, result);
goto done;
case TCP_FIN_WAIT_1:
case TCP_CLOSING:
case TCP_LAST_ACK:
/* In all these states we should retransmit a FINACK. */
tcp_send(dev, conn, TCP_FIN | TCP_ACK, hdrlen);
goto done;
}
}
}
/* The connection does not have outstanding data. Check if the TCP
* connection has been established.
*/
else if ((conn->tcpstateflags & TCP_STATE_MASK) == TCP_ESTABLISHED)
{
/* The TCP connection is established and, hence, should be bound
* to a device. Make sure that the polling device is the one that
* we are bound to.
*/
DEBUGASSERT(conn->dev != NULL);
if (dev == conn->dev)
{
#ifdef CONFIG_NET_TCP_KEEPALIVE
/* Is this an established connected with KeepAlive enabled? */
if (conn->keepalive)
{
socktimeo_t timeo;
uint32_t saveseq;
/* If this is the first probe, then the keepstart time is
* the time that the last ACK or data was received from the
* remote.
*
* On subsequent retries, keepstart is the time that the
* last probe was sent.
*/
if (conn->keepretries > 0)
{
timeo = (socktimeo_t)conn->keepintvl;
}
else
{
timeo = (socktimeo_t)conn->keepidle;
}
/* Yes... has the idle period elapsed with no data or ACK
* received from the remote peer?
*/
if (net_timeo(conn->keeptime, timeo))
{
/* Yes.. Has the retry count expired? */
if (conn->keepretries >= conn->keepcnt)
{
/* Yes... stop the network monitor, closing the connection and all sockets
* associated with the connection.
*/
tcp_stop_monitor(conn, TCP_ABORT);
}
else
{
unsigned int tcpiplen;
/* No.. we need to send another probe.
*
* Get the size of the IP header and the TCP header.
*/
#ifdef CONFIG_NET_IPv4
#ifdef CONFIG_NET_IPv6
if (conn->domain == PF_INET)
#endif
{
tcpiplen = IPv4_HDRLEN + TCP_HDRLEN;
}
#endif
#ifdef CONFIG_NET_IPv6
#ifdef CONFIG_NET_IPv4
else
#endif
{
tcpiplen = IPv6_HDRLEN + TCP_HDRLEN;
}
#endif
/* And send the probe (along with a garbage byte).
* The packet we sned must have these properties:
*
* - TCP_ACK flag (only) is set.
* - Sequence number is the sequence number of
* previously ACKed data, i.e., the expected
* sequence number minus one.
* - The data payload is one or two bytes.
*
* tcp_send() will send the TCP sequence number as
* conn->sndseq. Rather than creating a new
* interface, we spoof tcp_end() here:
*/
saveseq = tcp_getsequence(conn->sndseq);
tcp_setsequence(conn->sndseq, saveseq - 1);
tcp_send(dev, conn, TCP_ACK, tcpiplen + 1);
tcp_setsequence(conn->sndseq, saveseq);
/* Increment the number of un-ACKed bytes due to the dummy
* byte that we just sent.
*/
conn->unacked++;
#ifdef CONFIG_NET_TCP_WRITE_BUFFERS
/* Increment the un-ACKed sequence number */
conn->sndseq_max++;
#endif
/* Update for the next probe */
conn->keeptime = clock_systimer();
conn->keepretries++;
}
goto done;
}
}
#endif
/* There was no need for a retransmission and there was no
* need to probe the remote peer. We poll the application for
* new outgoing data.
*/
result = tcp_callback(dev, conn, TCP_POLL);
tcp_appsend(dev, conn, result);
goto done;
}
}
}
/* Nothing to be done */
dev->d_len = 0;
done:
return;
}
void tcp_timer(FAR struct net_driver_s *dev, FAR struct tcp_conn_s *conn,
int hsec)
{
uint32_t result;
uint8_t hdrlen;
/* Set up for the callback. We can't know in advance if the application
* is going to send a IPv4 or an IPv6 packet, so this setup may not
* actually be used. Furthermore, the TCP logic is required to call
* tcp_ipv4_select() or tcp_ipv6_select() prior to sending any packets.
* We will try to set the correct value here basic on the binding of
* the connection.
*/
#ifdef CONFIG_NET_IPv4
#ifdef CONFIG_NET_IPv6
if (conn->domain == PF_INET)
#endif
{
hdrlen = IPv4TCP_HDRLEN;
tcp_ipv4_select(dev);
}
#endif /* CONFIG_NET_IPv4 */
#ifdef CONFIG_NET_IPv6
#ifdef CONFIG_NET_IPv4
else
#endif
{
hdrlen = IPv6TCP_HDRLEN;
tcp_ipv6_select(dev);
}
#endif /* CONFIG_NET_IPv6 */
/* Increase the TCP sequence number */
tcp_nextsequence();
/* Reset the length variables. */
dev->d_len = 0;
dev->d_sndlen = 0;
/* Check if the connection is in a state in which we simply wait
* for the connection to time out. If so, we increase the
* connection's timer and remove the connection if it times
* out.
*/
if (conn->tcpstateflags == TCP_TIME_WAIT ||
conn->tcpstateflags == TCP_FIN_WAIT_2)
{
unsigned int newtimer;
/* Increment the connection timer */
newtimer = (unsigned int)conn->timer + hsec;
/* Check if the timer exceeds the timeout value */
if (newtimer >= TCP_TIME_WAIT_TIMEOUT)
{
/* Set the timer to the maximum value */
conn->timer = TCP_TIME_WAIT_TIMEOUT;
#ifdef CONFIG_NETDEV_MULTINIC
/* The TCP connection was established and, hence, should be bound
* to a device. Make sure that the polling device is the one that
* we are bound to.
*
* If not, then we will catch the timeout on the next poll from
* the correct device.
*/
DEBUGASSERT(conn->dev != NULL);
if (dev != conn->dev)
{
nllvdbg("TCP: TCP_CLOSED pending\n");
}
else
#endif
{
conn->tcpstateflags = TCP_CLOSED;
/* Notify upper layers about the timeout */
result = tcp_callback(dev, conn, TCP_TIMEDOUT);
nllvdbg("TCP state: TCP_CLOSED\n");
}
}
else
{
/* No timeout. Just update the incremented timer */
conn->timer = newtimer;
}
}
else if (conn->tcpstateflags != TCP_CLOSED)
{
/* If the connection has outstanding data, we increase the connection's
* timer and see if it has reached the RTO value in which case we
* retransmit.
*/
if (conn->unacked > 0)
{
/* The connection has outstanding data */
if (conn->timer > hsec)
{
/* Will not yet decrement to zero */
conn->timer -= hsec;
}
else
{
/* Will decrement to zero */
conn->timer = 0;
#ifdef CONFIG_NETDEV_MULTINIC
/* The TCP is connected and, hence, should be bound to a
* device. Make sure that the polling device is the one that
* we are bound to.
*
* If not, then we will catch the timeout on the next poll
* from the correct device.
*/
DEBUGASSERT(conn->dev != NULL);
if (dev != conn->dev)
{
nllvdbg("TCP: TCP_CLOSED pending\n");
goto done;
}
#endif
/* Should we close the connection? */
if (
#ifdef CONFIG_NET_TCP_WRITE_BUFFERS
conn->expired > 0 ||
#else
conn->nrtx == TCP_MAXRTX ||
#endif
((conn->tcpstateflags == TCP_SYN_SENT ||
conn->tcpstateflags == TCP_SYN_RCVD) &&
conn->nrtx == TCP_MAXSYNRTX)
)
{
conn->tcpstateflags = TCP_CLOSED;
nllvdbg("TCP state: TCP_CLOSED\n");
/* We call tcp_callback() with TCP_TIMEDOUT to
* inform the application that the connection has
* timed out.
*/
result = tcp_callback(dev, conn, TCP_TIMEDOUT);
/* We also send a reset packet to the remote host. */
tcp_send(dev, conn, TCP_RST | TCP_ACK, hdrlen);
goto done;
}
/* Exponential backoff. */
conn->timer = TCP_RTO << (conn->nrtx > 4 ? 4: conn->nrtx);
(conn->nrtx)++;
/* Ok, so we need to retransmit. We do this differently
* depending on which state we are in. In ESTABLISHED, we
* call upon the application so that it may prepare the
* data for the retransmit. In SYN_RCVD, we resend the
* SYNACK that we sent earlier and in LAST_ACK we have to
* retransmit our FINACK.
*/
#ifdef CONFIG_NET_STATISTICS
g_netstats.tcp.rexmit++;
#endif
switch (conn->tcpstateflags & TCP_STATE_MASK)
{
case TCP_SYN_RCVD:
/* In the SYN_RCVD state, we should retransmit our
* SYNACK.
*/
tcp_ack(dev, conn, TCP_ACK | TCP_SYN);
goto done;
case TCP_SYN_SENT:
/* In the SYN_SENT state, we retransmit out SYN. */
tcp_ack(dev, conn, TCP_SYN);
goto done;
case TCP_ESTABLISHED:
/* In the ESTABLISHED state, we call upon the application
* to do the actual retransmit after which we jump into
* the code for sending out the packet.
*/
result = tcp_callback(dev, conn, TCP_REXMIT);
tcp_rexmit(dev, conn, result);
goto done;
case TCP_FIN_WAIT_1:
case TCP_CLOSING:
case TCP_LAST_ACK:
/* In all these states we should retransmit a FINACK. */
tcp_send(dev, conn, TCP_FIN | TCP_ACK, hdrlen);
goto done;
}
}
}
/* The connection does not have outstanding data. Check if the TCP
* connection has been established.
*/
else if ((conn->tcpstateflags & TCP_STATE_MASK) == TCP_ESTABLISHED)
{
/* If there was no need for a retransmission, we poll the
* application for new data.
*/
#ifdef CONFIG_NETDEV_MULTINIC
/* The TCP connection is established and, hence, should be bound
* to a device. Make sure that the polling device is the one that
* we are bound to.
*/
DEBUGASSERT(conn->dev != NULL);
if (dev == conn->dev)
#endif
{
result = tcp_callback(dev, conn, TCP_POLL);
tcp_appsend(dev, conn, result);
goto done;
}
}
}
/* Nothing to be done */
dev->d_len = 0;
done:
return;
}
/**
* Implements the TCP state machine. Called by tcp_input. In some
* states tcp_receive() is called to receive data. The tcp_seg
* argument will be freed by the caller (tcp_input()) unless the
* recv_data pointer in the pcb is set.
*
* @param pcb the tcp_pcb for which a segment arrived
*
* @note the segment which arrived is saved in global variables, therefore only the pcb
* involved is passed as a parameter to this function
*/
static err_t
tcp_process(struct tcp_pcb *pcb)
{
struct tcp_seg *rseg;
u8_t acceptable = 0;
err_t err;
err = ERR_OK;
/* Process incoming RST segments. */
if (flags & TCP_RST) {
/* First, determine if the reset is acceptable. */
if (pcb->state == SYN_SENT) {
if (ackno == pcb->snd_nxt) {
acceptable = 1;
}
} else {
if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt,
pcb->rcv_nxt+pcb->rcv_wnd)) {
acceptable = 1;
}
}
if (acceptable) {
LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_process: Connection RESET\n"));
LWIP_ASSERT("tcp_input: pcb->state != CLOSED", pcb->state != CLOSED);
recv_flags |= TF_RESET;
pcb->flags &= ~TF_ACK_DELAY;
return ERR_RST;
} else {
LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_process: unacceptable reset seqno %"U32_F" rcv_nxt %"U32_F"\n",
seqno, pcb->rcv_nxt));
LWIP_DEBUGF(TCP_DEBUG, ("tcp_process: unacceptable reset seqno %"U32_F" rcv_nxt %"U32_F"\n",
seqno, pcb->rcv_nxt));
return ERR_OK;
}
}
if ((flags & TCP_SYN) && (pcb->state != SYN_SENT && pcb->state != SYN_RCVD)) {
/* Cope with new connection attempt after remote end crashed */
tcp_ack_now(pcb);
return ERR_OK;
}
/* Update the PCB (in)activity timer. */
pcb->tmr = tcp_ticks;
pcb->keep_cnt_sent = 0;
tcp_parseopt(pcb);
/* Do different things depending on the TCP state. */
switch (pcb->state) {
case SYN_SENT:
LWIP_DEBUGF(TCP_INPUT_DEBUG, ("SYN-SENT: ackno %"U32_F" pcb->snd_nxt %"U32_F" unacked %"U32_F"\n", ackno,
pcb->snd_nxt, ntohl(pcb->unacked->tcphdr->seqno)));
/* received SYN ACK with expected sequence number? */
if ((flags & TCP_ACK) && (flags & TCP_SYN)
&& ackno == ntohl(pcb->unacked->tcphdr->seqno) + 1) {
pcb->snd_buf++;
pcb->rcv_nxt = seqno + 1;
pcb->rcv_ann_right_edge = pcb->rcv_nxt;
pcb->lastack = ackno;
pcb->snd_wnd = tcphdr->wnd;
pcb->snd_wl1 = seqno - 1; /* initialise to seqno - 1 to force window update */
pcb->state = ESTABLISHED;
#if TCP_CALCULATE_EFF_SEND_MSS
pcb->mss = tcp_eff_send_mss(pcb->mss, &(pcb->remote_ip));
#endif /* TCP_CALCULATE_EFF_SEND_MSS */
/* Set ssthresh again after changing pcb->mss (already set in tcp_connect
* but for the default value of pcb->mss) */
pcb->ssthresh = pcb->mss * 10;
pcb->cwnd = ((pcb->cwnd == 1) ? (pcb->mss * 2) : pcb->mss);
LWIP_ASSERT("pcb->snd_queuelen > 0", (pcb->snd_queuelen > 0));
--pcb->snd_queuelen;
LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_process: SYN-SENT --queuelen %"U16_F"\n", (u16_t)pcb->snd_queuelen));
rseg = pcb->unacked;
pcb->unacked = rseg->next;
/* If there's nothing left to acknowledge, stop the retransmit
timer, otherwise reset it to start again */
if(pcb->unacked == NULL)
pcb->rtime = -1;
else {
pcb->rtime = 0;
pcb->nrtx = 0;
}
tcp_seg_free(rseg);
/* Call the user specified function to call when sucessfully
* connected. */
TCP_EVENT_CONNECTED(pcb, ERR_OK, err);
tcp_ack_now(pcb);
}
/* received ACK? possibly a half-open connection */
else if (flags & TCP_ACK) {
/* send a RST to bring the other side in a non-synchronized state. */
tcp_rst(ackno, seqno + tcplen, &(iphdr->dest), &(iphdr->src),
tcphdr->dest, tcphdr->src);
}
break;
case SYN_RCVD:
if (flags & TCP_ACK) {
/* expected ACK number? */
if (TCP_SEQ_BETWEEN(ackno, pcb->lastack+1, pcb->snd_nxt)) {
u16_t old_cwnd;
pcb->state = ESTABLISHED;
LWIP_DEBUGF(TCP_DEBUG, ("TCP connection established %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
#if LWIP_CALLBACK_API
LWIP_ASSERT("pcb->accept != NULL", pcb->accept != NULL);
#endif
/* Call the accept function. */
TCP_EVENT_ACCEPT(pcb, ERR_OK, err);
if (err != ERR_OK) {
/* If the accept function returns with an error, we abort
* the connection. */
tcp_abort(pcb);
return ERR_ABRT;
}
old_cwnd = pcb->cwnd;
/* If there was any data contained within this ACK,
* we'd better pass it on to the application as well. */
tcp_receive(pcb);
/* Prevent ACK for SYN to generate a sent event */
if (pcb->acked != 0) {
pcb->acked--;
}
pcb->cwnd = ((old_cwnd == 1) ? (pcb->mss * 2) : pcb->mss);
if (recv_flags & TF_GOT_FIN) {
tcp_ack_now(pcb);
pcb->state = CLOSE_WAIT;
}
}
/* incorrect ACK number */
else {
/* send RST */
tcp_rst(ackno, seqno + tcplen, &(iphdr->dest), &(iphdr->src),
tcphdr->dest, tcphdr->src);
}
} else if ((flags & TCP_SYN) && (seqno == pcb->rcv_nxt - 1)) {
/* Looks like another copy of the SYN - retransmit our SYN-ACK */
tcp_rexmit(pcb);
}
break;
case CLOSE_WAIT:
/* FALLTHROUGH */
case ESTABLISHED:
tcp_receive(pcb);
if (recv_flags & TF_GOT_FIN) { /* passive close */
tcp_ack_now(pcb);
pcb->state = CLOSE_WAIT;
}
break;
case FIN_WAIT_1:
tcp_receive(pcb);
if (recv_flags & TF_GOT_FIN) {
if ((flags & TCP_ACK) && (ackno == pcb->snd_nxt)) {
LWIP_DEBUGF(TCP_DEBUG,
("TCP connection closed: FIN_WAIT_1 %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
tcp_ack_now(pcb);
tcp_pcb_purge(pcb);
TCP_RMV(&tcp_active_pcbs, pcb);
pcb->state = TIME_WAIT;
TCP_REG(&tcp_tw_pcbs, pcb);
} else {
tcp_ack_now(pcb);
pcb->state = CLOSING;
}
} else if ((flags & TCP_ACK) && (ackno == pcb->snd_nxt)) {
pcb->state = FIN_WAIT_2;
}
break;
case FIN_WAIT_2:
tcp_receive(pcb);
if (recv_flags & TF_GOT_FIN) {
LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: FIN_WAIT_2 %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
tcp_ack_now(pcb);
tcp_pcb_purge(pcb);
TCP_RMV(&tcp_active_pcbs, pcb);
pcb->state = TIME_WAIT;
TCP_REG(&tcp_tw_pcbs, pcb);
}
break;
case CLOSING:
tcp_receive(pcb);
if (flags & TCP_ACK && ackno == pcb->snd_nxt) {
LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: CLOSING %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
tcp_pcb_purge(pcb);
TCP_RMV(&tcp_active_pcbs, pcb);
pcb->state = TIME_WAIT;
TCP_REG(&tcp_tw_pcbs, pcb);
}
break;
case LAST_ACK:
tcp_receive(pcb);
if (flags & TCP_ACK && ackno == pcb->snd_nxt) {
LWIP_DEBUGF(TCP_DEBUG, ("TCP connection closed: LAST_ACK %"U16_F" -> %"U16_F".\n", inseg.tcphdr->src, inseg.tcphdr->dest));
/* bugfix #21699: don't set pcb->state to CLOSED here or we risk leaking segments */
recv_flags |= TF_CLOSED;
}
break;
default:
break;
}
return ERR_OK;
}
