/**************************************************************************** * net/tcp/tcp_timer.c * Poll for the availability of TCP TX data * * Copyright (C) 2007-2010, 2015 Gregory Nutt. All rights reserved. * Author: Gregory Nutt * * Adapted for NuttX from logic in uIP which also has a BSD-like license: * * Original author Adam Dunkels * Copyright () 2001-2003, Adam Dunkels. * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. The name of the author may not be used to endorse or promote * products derived from this software without specific prior * written permission. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. * ****************************************************************************/ /**************************************************************************** * Included Files ****************************************************************************/ #include #if defined(CONFIG_NET) && defined(CONFIG_NET_TCP) #include #include #include #include #include #include #include "devif/devif.h" #include "tcp/tcp.h" /**************************************************************************** * Pre-processor Definitions ****************************************************************************/ /**************************************************************************** * Public Variables ****************************************************************************/ /**************************************************************************** * Private Variables ****************************************************************************/ /**************************************************************************** * Private Functions ****************************************************************************/ /**************************************************************************** * Public Functions ****************************************************************************/ /**************************************************************************** * Name: tcp_timer * * Description: * Handle a TCP timer expiration for the provided TCP connection * * Parameters: * dev - The device driver structure to use in the send operation * conn - The TCP "connection" to poll for TX data * hsed - The polling interval in halves of a second * * Return: * None * * Assumptions: * Called from the interrupt level or with interrupts disabled. * ****************************************************************************/ void tcp_timer(FAR struct net_driver_s *dev, FAR struct tcp_conn_s *conn, int hsec) { uint8_t hdrlen; uint8_t result; /* 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) { /* Increment the connection timer */ conn->timer += hsec; if (conn->timer >= TCP_TIME_WAIT_TIMEOUT) { conn->tcpstateflags = TCP_CLOSED; /* Notify upper layers about the timeout */ result = tcp_callback(dev, conn, TCP_TIMEDOUT); nllvdbg("TCP state: TCP_CLOSED\n"); } } 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; /* 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 */ else if ((conn->tcpstateflags & TCP_STATE_MASK) == TCP_ESTABLISHED) { /* If there was no need for a retransmission, we poll the * application for new 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; } #endif /* CONFIG_NET && CONFIG_NET_TCP */