/**************************************************************************** * net/tcp/tcp_appsend.c * * Copyright (C) 2007-2010, 2014 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 #include "devif/devif.h" #include "tcp/tcp.h" /**************************************************************************** * Public Functions ****************************************************************************/ /**************************************************************************** * Name: tcp_appsend * * Description: * Handle application or TCP protocol response. If this function is called * with dev->d_sndlen > 0, then this is an application attempting to send * packet. * * Input Parameters: * dev - The device driver structure to use in the send operation * conn - The TCP connection structure holding connection information * result - App result event sent * * Returned Value: * None * * Assumptions: * The network is locked. * ****************************************************************************/ void tcp_appsend(FAR struct net_driver_s *dev, FAR struct tcp_conn_s *conn, uint16_t result) { uint8_t hdrlen; ninfo("result: %04x d_sndlen: %d conn->tx_unacked: %" PRId32 "\n", result, dev->d_sndlen, (uint32_t)conn->tx_unacked); /* Need to update the recv window? */ if (tcp_should_send_recvwindow(conn)) { result |= TCP_SNDACK; #ifdef CONFIG_NET_TCP_DELAYED_ACK conn->rx_unackseg = 0; #endif } #ifdef CONFIG_NET_TCP_DELAYED_ACK /* Did the caller request that an ACK be sent? */ else if ((result & TCP_SNDACK) != 0) { /* Yes.. Handle delayed acknowledgments */ /* Reset the ACK timer in any event. */ conn->rx_acktimer = 0; /* Per RFC 1122: "...in a stream of full-sized segments there * SHOULD be an ACK for at least every second segment." * * NOTES: * 1. If there is a data payload or other flags to be sent with the * outgoing packet, then we may as well include the ACK too. * 2. The RFC refers to full-size segments. It is not clear what * "full-size" means. Does that mean that the payload is the size * of the MSS? Payload size is not considered other there being * a payload or or not. Should there be some special action for * small payloads of size < MSS? * 3. Experimentation shows that Windows and Linux behave somewhat * differently; they delay the ACKs for many more segments (6 or * more). Delaying for more segments would provide less network * traffic and better performance but seems non-compliant. */ if (conn->rx_unackseg > 0 || dev->d_sndlen > 0 || result != TCP_SNDACK) { /* Reset the delayed ACK state and send the ACK with this packet. */ conn->rx_unackseg = 0; } else { /* This is only an ACK and there is no pending delayed ACK and * no TX data is being sent. Indicate that there is one un-ACKed * segment and don't send anything now. */ conn->rx_unackseg = 1; return; } } /* If there are data to be sent in the same direction as the ACK before * the second data packet is received and the delay timer expires, the ACK * is piggybacked with the data segment and sent immediately. */ else if (dev->d_sndlen > 0 && conn->rx_unackseg > 0) { result |= TCP_SNDACK; conn->rx_unackseg = 0; } #endif /* 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 If the device went down */ if ((result & NETDEV_DOWN) != 0) { /* If so, make sure that the connection is marked closed * and do not try to send anything. */ dev->d_sndlen = 0; conn->tcpstateflags = TCP_CLOSED; ninfo("TCP state: NETDEV_DOWN\n"); } /* Check for connection aborted */ else if ((result & TCP_ABORT) != 0) { dev->d_sndlen = 0; conn->tcpstateflags = TCP_CLOSED; ninfo("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->tx_unacked = 1; conn->nrtx = 0; #ifdef CONFIG_NET_TCP_WRITE_BUFFERS conn->sndseq_max = tcp_getsequence(conn->sndseq) + 1; #endif ninfo("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 <= 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->tx_unacked += dev->d_sndlen; /* The application cannot send more than what is allowed by the * MSS (the minimum 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); } } /**************************************************************************** * Name: tcp_rexmit * * Description: * Handle application retransmission * * Input Parameters: * dev - The device driver structure to use in the send operation * conn - The TCP connection structure holding connection information * result - App result event sent * * Returned Value: * None * * Assumptions: * The network is locked. * ****************************************************************************/ void tcp_rexmit(FAR struct net_driver_s *dev, FAR struct tcp_conn_s *conn, uint16_t result) { uint8_t hdrlen; ninfo("result: %04x d_sndlen: %d conn->tx_unacked: %" PRId32 "\n", result, dev->d_sndlen, (uint32_t)conn->tx_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 */ /* If the application has data to be sent, or if the incoming packet had * new data in it, we must send out a packet. */ #ifdef CONFIG_NET_TCP_WRITE_BUFFERS if (dev->d_sndlen > 0) #else if ((result & TCP_REXMIT) != 0 && dev->d_sndlen > 0 && conn->tx_unacked > 0) { uint32_t saveseq; /* According to RFC 6298 (5.4), retransmit the earliest segment * that has not been acknowledged by the TCP receiver. */ saveseq = tcp_getsequence(conn->sndseq); tcp_setsequence(conn->sndseq, conn->rexmit_seq); tcp_send(dev, conn, TCP_ACK | TCP_PSH, dev->d_sndlen + hdrlen); tcp_setsequence(conn->sndseq, saveseq); } else if (dev->d_sndlen > 0 && conn->tx_unacked > 0) #endif { uint32_t seq; /* We always set the ACK flag in response packets adding the length of * the IP and TCP headers. */ tcp_send(dev, conn, TCP_ACK | TCP_PSH, dev->d_sndlen + hdrlen); /* Advance sndseq */ seq = tcp_getsequence(conn->sndseq); tcp_setsequence(conn->sndseq, seq + dev->d_sndlen); } /* If there is no data to send, just send out a pure ACK if one is * requested. */ else if ((result & TCP_SNDACK) != 0) { tcp_send(dev, conn, TCP_ACK, hdrlen); } /* There is nothing to do -- drop the packet */ else { dev->d_len = 0; } } #endif /* CONFIG_NET && CONFIG_NET_TCP */