/**************************************************************************** * net/tcp/tcp_input.c * Handling incoming TCP input * * Copyright (C) 2007-2014, 2017-2019, 2020 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 #include #include "devif/devif.h" #include "utils/utils.h" #include "tcp/tcp.h" /**************************************************************************** * Pre-processor Definitions ****************************************************************************/ #define IPv4BUF ((FAR struct ipv4_hdr_s *)&dev->d_buf[NET_LL_HDRLEN(dev)]) /**************************************************************************** * Private Functions ****************************************************************************/ /**************************************************************************** * Name: tcp_input * * Description: * Handle incoming TCP input * * Input Parameters: * dev - The device driver structure containing the received TCP packet. * domain - IP domain (PF_INET or PF_INET6) * iplen - Length of the IP header (IPv4_HDRLEN or IPv6_HDRLEN). * * Returned Value: * None * * Assumptions: * The network is locked. * ****************************************************************************/ static void tcp_input(FAR struct net_driver_s *dev, uint8_t domain, unsigned int iplen) { FAR struct tcp_hdr_s *tcp; FAR struct tcp_conn_s *conn = NULL; unsigned int tcpiplen; unsigned int hdrlen; uint16_t tmp16; uint16_t flags; uint16_t result; uint8_t opt; int len; int i; #ifdef CONFIG_NET_STATISTICS /* Bump up the count of TCP packets received */ g_netstats.tcp.recv++; #endif /* Get a pointer to the TCP header. The TCP header lies just after the * the link layer header and the IP header. */ tcp = (FAR struct tcp_hdr_s *)&dev->d_buf[iplen + NET_LL_HDRLEN(dev)]; /* Get the size of the IP header and the TCP header. * * REVISIT: TCP header is *not* a constant! It can be larger if the * TCP header includes options. The constant TCP_HDRLEN should be * replaced with the macro TCP_OPT_HDRLEN(n) which will calculate the * correct header length in all cases. */ tcpiplen = iplen + TCP_HDRLEN; /* Get the size of the link layer header, the IP and TCP header */ hdrlen = tcpiplen + NET_LL_HDRLEN(dev); /* Start of TCP input header processing code. */ if (tcp_chksum(dev) != 0xffff) { /* Compute and check the TCP checksum. */ #ifdef CONFIG_NET_STATISTICS g_netstats.tcp.drop++; g_netstats.tcp.chkerr++; #endif nwarn("WARNING: Bad TCP checksum\n"); goto drop; } /* Demultiplex this segment. First check any active connections. */ conn = tcp_active(dev, tcp); if (conn) { /* We found an active connection.. Check for the subsequent SYN * arriving in TCP_SYN_RCVD state after the SYNACK packet was * lost. To avoid other issues, reset any active connection * where a SYN arrives in a state != TCP_SYN_RCVD. */ if ((conn->tcpstateflags & TCP_STATE_MASK) != TCP_SYN_RCVD && (tcp->flags & TCP_CTL) == TCP_SYN) { nwarn("WARNING: SYN in TCP_SYN_RCVD\n"); goto reset; } else { goto found; } } /* If we didn't find an active connection that expected the packet, * either (1) this packet is an old duplicate, or (2) this is a SYN packet * destined for a connection in LISTEN. If the SYN flag isn't set, * it is an old packet and we send a RST. */ if ((tcp->flags & TCP_CTL) == TCP_SYN) { /* This is a SYN packet for a connection. Find the connection * listening on this port. */ tmp16 = tcp->destport; #if defined(CONFIG_NET_IPv4) && defined(CONFIG_NET_IPv6) if (tcp_islistener(tmp16, domain)) #else if (tcp_islistener(tmp16)) #endif { /* We matched the incoming packet with a connection in LISTEN. * We now need to create a new connection and send a SYNACK in * response. */ /* First allocate a new connection structure and see if there is * any user application to accept it. */ conn = tcp_alloc_accept(dev, tcp); if (conn) { /* The connection structure was successfully allocated and has * been initialized in the TCP_SYN_RECVD state. The expected * sequence of events is then the rest of the 3-way handshake: * * 1. We just received a TCP SYN packet from a remote host. * 2. We will send the SYN-ACK response below (perhaps * repeatedly in the event of a timeout) * 3. Then we expect to receive an ACK from the remote host * indicated the TCP socket connection is ESTABLISHED. * * Possible failure: * * 1. The ACK is never received. This will be handled by * a timeout managed by tcp_timer(). * 2. The listener "unlistens()". This will be handled by * the failure of tcp_accept_connection() when the ACK is * received. */ conn->crefs = 1; } if (!conn) { /* Either (1) all available connections are in use, or (2) * there is no application in place to accept the connection. * We drop packet and hope that the remote end will retransmit * the packet at a time when we have more spare connections * or someone waiting to accept the connection. */ #ifdef CONFIG_NET_STATISTICS g_netstats.tcp.syndrop++; #endif nerr("ERROR: No free TCP connections\n"); goto drop; } net_incr32(conn->rcvseq, 1); /* Parse the TCP MSS option, if present. */ if ((tcp->tcpoffset & 0xf0) > 0x50) { for (i = 0; i < ((tcp->tcpoffset >> 4) - 5) << 2 ; ) { opt = dev->d_buf[hdrlen + i]; if (opt == TCP_OPT_END) { /* End of options. */ break; } else if (opt == TCP_OPT_NOOP) { /* NOP option. */ ++i; } else if (opt == TCP_OPT_MSS && dev->d_buf[hdrlen + 1 + i] == TCP_OPT_MSS_LEN) { uint16_t tcp_mss = TCP_MSS(dev, iplen); /* An MSS option with the right option length. */ tmp16 = ((uint16_t)dev->d_buf[hdrlen + 2 + i] << 8) | (uint16_t)dev->d_buf[hdrlen + 3 + i]; conn->mss = tmp16 > tcp_mss ? tcp_mss : tmp16; /* And we are done processing options. */ break; } else { /* All other options have a length field, so that we * easily can skip past them. */ if (dev->d_buf[hdrlen + 1 + i] == 0) { /* If the length field is zero, the options are * malformed and we don't process them further. */ break; } i += dev->d_buf[hdrlen + 1 + i]; } } } /* Our response will be a SYNACK. */ tcp_synack(dev, conn, TCP_ACK | TCP_SYN); return; } } nwarn("WARNING: SYN with no listener (or old packet) .. reset\n"); /* This is (1) an old duplicate packet or (2) a SYN packet but with * no matching listener found. Send RST packet in either case. */ reset: /* We do not send resets in response to resets. */ if ((tcp->flags & TCP_RST) != 0) { goto drop; } #ifdef CONFIG_NET_STATISTICS g_netstats.tcp.synrst++; #endif tcp_reset(dev); return; found: /* Update the connection's window size */ conn->winsize = ((uint16_t)tcp->wnd[0] << 8) + (uint16_t)tcp->wnd[1]; flags = 0; /* We do a very naive form of TCP reset processing; we just accept * any RST and kill our connection. We should in fact check if the * sequence number of this reset is within our advertised window * before we accept the reset. */ if ((tcp->flags & TCP_RST) != 0) { FAR struct tcp_conn_s *listener = NULL; /* An RST received during the 3-way connection handshake requires * little more clean-up. */ if ((conn->tcpstateflags & TCP_STATE_MASK) == TCP_SYN_RCVD) { conn->tcpstateflags = TCP_CLOSED; nwarn("WARNING: RESET in TCP_SYN_RCVD\n"); /* Notify the listener for the connection of the reset event */ #if defined(CONFIG_NET_IPv4) && defined(CONFIG_NET_IPv6) listener = tcp_findlistener(conn->lport, domain); #else listener = tcp_findlistener(conn->lport); #endif /* We must free this TCP connection structure; this connection * will never be established. There should only be one reference * on this connection when we allocated for the connection. */ DEBUGASSERT(conn->crefs == 1); conn->crefs = 0; tcp_free(conn); } else { conn->tcpstateflags = TCP_CLOSED; nwarn("WARNING: RESET TCP state: TCP_CLOSED\n"); /* Notify this connection of the reset event */ listener = conn; } /* Perform the TCP_ABORT callback and drop the packet */ if (listener != NULL) { tcp_callback(dev, listener, TCP_ABORT); } goto drop; } /* Calculated the length of the data, if the application has sent * any data to us. */ len = (tcp->tcpoffset >> 4) << 2; /* d_len will contain the length of the actual TCP data. This is * calculated by subtracting the length of the TCP header (in * len) and the length of the IP header. */ dev->d_len -= (len + iplen); #ifdef CONFIG_NET_TCP_KEEPALIVE /* Check for a to KeepAlive probes. These packets have these properties: * * - TCP_ACK flag is set. SYN/FIN/RST never appear in a Keepalive probe. * - 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. * * We would expect a KeepAlive only in the ESTABLISHED state and only after * some time has elapsed with no network activity. If there is un-ACKed * data, then we will let the normal TCP re-transmission logic handle that * case. */ if ((tcp->flags & TCP_ACK) != 0 && (tcp->flags & (TCP_SYN | TCP_FIN | TCP_RST)) == 0 && (conn->tcpstateflags & TCP_STATE_MASK) == TCP_ESTABLISHED && (dev->d_len == 0 || dev->d_len == 1) && conn->tx_unacked <= 0) { uint32_t ackseq; uint32_t rcvseq; /* Get the sequence number of that has just been acknowledged by this * incoming packet. */ ackseq = tcp_getsequence(tcp->seqno); rcvseq = tcp_getsequence(conn->rcvseq); if (ackseq < rcvseq) { /* Send a "normal" acknowledgment of the KeepAlive probe */ tcp_send(dev, conn, TCP_ACK, tcpiplen); return; } } #endif /* Check if the sequence number of the incoming packet is what we are * expecting next. If not, we send out an ACK with the correct numbers * in, unless we are in the SYN_RCVD state and receive a SYN, in which * case we should retransmit our SYNACK (which is done further down). */ if (!((((conn->tcpstateflags & TCP_STATE_MASK) == TCP_SYN_SENT) && ((tcp->flags & TCP_CTL) == (TCP_SYN | TCP_ACK))) || (((conn->tcpstateflags & TCP_STATE_MASK) == TCP_SYN_RCVD) && ((tcp->flags & TCP_CTL) == TCP_SYN)))) { if ((dev->d_len > 0 || ((tcp->flags & (TCP_SYN | TCP_FIN)) != 0)) && memcmp(tcp->seqno, conn->rcvseq, 4) != 0) { tcp_send(dev, conn, TCP_ACK, tcpiplen); return; } } /* Check if the incoming segment acknowledges any outstanding data. If so, * we update the sequence number, reset the length of the outstanding * data, calculate RTT estimations, and reset the retransmission timer. */ if ((tcp->flags & TCP_ACK) != 0 && conn->tx_unacked > 0) { uint32_t unackseq; uint32_t ackseq; /* The next sequence number is equal to the current sequence * number (sndseq) plus the size of the outstanding, unacknowledged * data (tx_unacked). */ #ifdef CONFIG_NET_TCP_WRITE_BUFFERS unackseq = conn->sndseq_max; #else unackseq = tcp_addsequence(conn->sndseq, conn->tx_unacked); #endif /* Get the sequence number of that has just been acknowledged by this * incoming packet. */ ackseq = tcp_getsequence(tcp->ackno); /* Check how many of the outstanding bytes have been acknowledged. For * most send operations, this should always be true. However, * the send() API sends data ahead when it can without waiting for * the ACK. In this case, the 'ackseq' could be less than then the * new sequence number. */ if (ackseq <= unackseq) { /* Calculate the new number of outstanding, unacknowledged bytes */ conn->tx_unacked = unackseq - ackseq; } else { /* What would it mean if ackseq > unackseq? The peer has ACKed * more bytes than we think we have sent? Someone has lost it. * Complain and reset the number of outstanding, unacknowledged * bytes */ if ((conn->tcpstateflags & TCP_STATE_MASK) == TCP_ESTABLISHED) { nwarn("WARNING: ackseq > unackseq\n"); nwarn("sndseq=%u tx_unacked=%u unackseq=%u ackseq=%u\n", tcp_getsequence(conn->sndseq), conn->tx_unacked, unackseq, ackseq); conn->tx_unacked = 0; } } /* Update sequence number to the unacknowledge sequence number. If * there is still outstanding, unacknowledged data, then this will * be beyond ackseq. */ ninfo("sndseq: %08x->%08x unackseq: %08x new tx_unacked: %d\n", tcp_getsequence(conn->sndseq), ackseq, unackseq, conn->tx_unacked); tcp_setsequence(conn->sndseq, ackseq); /* Do RTT estimation, unless we have done retransmissions. */ if (conn->nrtx == 0) { signed char m; m = conn->rto - conn->timer; /* This is taken directly from VJs original code in his paper */ m = m - (conn->sa >> 3); conn->sa += m; if (m < 0) { m = -m; } m = m - (conn->sv >> 2); conn->sv += m; conn->rto = (conn->sa >> 3) + conn->sv; } /* Set the acknowledged flag. */ flags |= TCP_ACKDATA; /* Reset the retransmission timer. */ conn->timer = conn->rto; } /* Do different things depending on in what state the connection is. */ switch (conn->tcpstateflags & TCP_STATE_MASK) { /* CLOSED and LISTEN are not handled here. CLOSE_WAIT is not * implemented, since we force the application to close when the * peer sends a FIN (hence the application goes directly from * ESTABLISHED to LAST_ACK). */ case TCP_SYN_RCVD: /* In SYN_RCVD we have sent out a SYNACK in response to a SYN, and * we are waiting for an ACK that acknowledges the data we sent * out the last time. Therefore, we want to have the TCP_ACKDATA * flag set. If so, we enter the ESTABLISHED state. */ if ((flags & TCP_ACKDATA) != 0) { /* The three way handshake is complete and the TCP connection * is now in the ESTABLISHED state. */ conn->tcpstateflags = TCP_ESTABLISHED; /* Wake up any listener waiting for a connection on this port */ if (tcp_accept_connection(dev, conn, tcp->destport) != OK) { /* No more listener for current port. We can free conn here * because it has not been shared with upper layers yet as * handshake is not complete */ nwarn("WARNING: Listen canceled while waiting for ACK on " "port %d\n", ntohs(tcp->destport)); /* Free the connection structure */ conn->crefs = 0; tcp_free(conn); conn = NULL; /* And send a reset packet to the remote host. */ goto reset; } #ifdef CONFIG_NET_TCP_WRITE_BUFFERS conn->isn = tcp_getsequence(tcp->ackno); tcp_setsequence(conn->sndseq, conn->isn); conn->sent = 0; conn->sndseq_max = 0; #endif conn->tx_unacked = 0; flags = TCP_CONNECTED; ninfo("TCP state: TCP_ESTABLISHED\n"); if (dev->d_len > 0) { flags |= TCP_NEWDATA; net_incr32(conn->rcvseq, dev->d_len); } dev->d_sndlen = 0; result = tcp_callback(dev, conn, flags); tcp_appsend(dev, conn, result); return; } /* We need to retransmit the SYNACK */ if ((tcp->flags & TCP_CTL) == TCP_SYN) { tcp_synack(dev, conn, TCP_ACK | TCP_SYN); return; } goto drop; case TCP_SYN_SENT: /* In SYN_SENT, we wait for a SYNACK that is sent in response to * our SYN. The rcvseq is set to sequence number in the SYNACK * plus one, and we send an ACK. We move into the ESTABLISHED * state. */ if ((flags & TCP_ACKDATA) != 0 && (tcp->flags & TCP_CTL) == (TCP_SYN | TCP_ACK)) { /* Parse the TCP MSS option, if present. */ if ((tcp->tcpoffset & 0xf0) > 0x50) { for (i = 0; i < ((tcp->tcpoffset >> 4) - 5) << 2 ; ) { opt = dev->d_buf[hdrlen + i]; if (opt == TCP_OPT_END) { /* End of options. */ break; } else if (opt == TCP_OPT_NOOP) { /* NOP option. */ ++i; } else if (opt == TCP_OPT_MSS && dev->d_buf[hdrlen + 1 + i] == TCP_OPT_MSS_LEN) { uint16_t tcp_mss = TCP_MSS(dev, iplen); /* An MSS option with the right option length. */ tmp16 = (dev->d_buf[hdrlen + 2 + i] << 8) | dev->d_buf[hdrlen + 3 + i]; conn->mss = tmp16 > tcp_mss ? tcp_mss : tmp16; /* And we are done processing options. */ break; } else { /* All other options have a length field, so that we * easily can skip past them. */ if (dev->d_buf[hdrlen + 1 + i] == 0) { /* If the length field is zero, the options are * malformed and we don't process them further. */ break; } i += dev->d_buf[hdrlen + 1 + i]; } } } conn->tcpstateflags = TCP_ESTABLISHED; memcpy(conn->rcvseq, tcp->seqno, 4); net_incr32(conn->rcvseq, 1); conn->tx_unacked = 0; #ifdef CONFIG_NET_TCP_WRITE_BUFFERS conn->isn = tcp_getsequence(tcp->ackno); tcp_setsequence(conn->sndseq, conn->isn); #endif dev->d_len = 0; dev->d_sndlen = 0; ninfo("TCP state: TCP_ESTABLISHED\n"); result = tcp_callback(dev, conn, TCP_CONNECTED | TCP_NEWDATA); tcp_appsend(dev, conn, result); return; } /* Inform the application that the connection failed */ tcp_callback(dev, conn, TCP_ABORT); /* The connection is closed after we send the RST */ conn->tcpstateflags = TCP_CLOSED; ninfo("Connection failed - TCP state: TCP_CLOSED\n"); /* We do not send resets in response to resets. */ if ((tcp->flags & TCP_RST) != 0) { goto drop; } tcp_reset(dev); return; case TCP_ESTABLISHED: /* In the ESTABLISHED state, we call upon the application to feed * data into the d_buf. If the TCP_ACKDATA flag is set, the * application should put new data into the buffer, otherwise we are * retransmitting an old segment, and the application should put that * data into the buffer. * * If the incoming packet is a FIN, we should close the connection on * this side as well, and we send out a FIN and enter the LAST_ACK * state. We require that there is no outstanding data; otherwise * the sequence numbers will be screwed up. */ if ((tcp->flags & TCP_FIN) != 0 && (conn->tcpstateflags & TCP_STOPPED) == 0) { /* Needs to be investigated further. * Windows often sends FIN packets together with the last ACK for * the received data. So the socket layer has to get this ACK * even if the connection is going to be closed. */ #if 0 if (conn->tx_unacked > 0) { goto drop; } #endif /* Update the sequence number and indicate that the connection * has been closed. */ net_incr32(conn->rcvseq, dev->d_len + 1); flags |= TCP_CLOSE; if (dev->d_len > 0) { flags |= TCP_NEWDATA; } tcp_callback(dev, conn, flags); conn->tcpstateflags = TCP_LAST_ACK; 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_LAST_ACK\n"); tcp_send(dev, conn, TCP_FIN | TCP_ACK, tcpiplen); return; } /* Check the URG flag. If this is set, the segment carries urgent * data that we must pass to the application. */ if ((tcp->flags & TCP_URG) != 0) { #ifdef CONFIG_NET_TCPURGDATA dev->d_urglen = (tcp->urgp[0] << 8) | tcp->urgp[1]; if (dev->d_urglen > dev->d_len) { /* There is more urgent data in the next segment to come. */ dev->d_urglen = dev->d_len; } net_incr32(conn->rcvseq, dev->d_urglen); dev->d_len -= dev->d_urglen; dev->d_urgdata = dev->d_appdata; dev->d_appdata += dev->d_urglen; } else { dev->d_urglen = 0; #else /* CONFIG_NET_TCPURGDATA */ dev->d_appdata = ((FAR uint8_t *)dev->d_appdata) + ((tcp->urgp[0] << 8) | tcp->urgp[1]); dev->d_len -= (tcp->urgp[0] << 8) | tcp->urgp[1]; #endif /* CONFIG_NET_TCPURGDATA */ } #ifdef CONFIG_NET_TCP_KEEPALIVE /* If the established socket receives an ACK or any kind of data * from the remote peer (whether we accept it or not), then reset * the keep alive timer. */ if (conn->keepalive && (dev->d_len > 0 || (tcp->flags & TCP_ACK) != 0)) { /* Reset the last known "alive" time. * * REVISIT: At this level, we don't actually know if keep- * alive is enabled for this connection. */ conn->keeptime = clock_systime_ticks(); conn->keepretries = 0; } #endif /* If d_len > 0 we have TCP data in the packet, and we flag this * by setting the TCP_NEWDATA flag. If the application has stopped * the data flow using TCP_STOPPED, we must not accept any data * packets from the remote host. */ if (dev->d_len > 0 && (conn->tcpstateflags & TCP_STOPPED) == 0) { flags |= TCP_NEWDATA; } /* If this packet constitutes an ACK for outstanding data (flagged * by the TCP_ACKDATA flag), we should call the application since it * might want to send more data. If the incoming packet had data * from the peer (as flagged by the TCP_NEWDATA flag), the * application must also be notified. * * When the application is called, the d_len field * contains the length of the incoming data. The application can * access the incoming data through the global pointer * d_appdata, which usually points hdrlen bytes into the d_buf * array. * * If the application wishes to send any data, this data should be * put into the d_appdata and the length of the data should be * put into d_len. If the application don't have any data to * send, d_len must be set to 0. */ if ((flags & (TCP_NEWDATA | TCP_ACKDATA)) != 0) { /* Clear sndlen and remember the size in d_len. The application * may modify d_len and we will need this value later when we * update the sequence number. */ dev->d_sndlen = 0; len = dev->d_len; /* Provide the packet to the application */ result = tcp_callback(dev, conn, flags); /* If the application successfully handled the incoming data, * then TCP_SNDACK will be set in the result. In this case, * we need to update the sequence number. The ACK will be * send by tcp_appsend(). */ if ((result & TCP_SNDACK) != 0) { /* Update the sequence number using the saved length */ net_incr32(conn->rcvseq, len); } /* Send the response, ACKing the data or not, as appropriate */ tcp_appsend(dev, conn, result); return; } goto drop; case TCP_LAST_ACK: /* We can close this connection if the peer has acknowledged our * FIN. This is indicated by the TCP_ACKDATA flag. */ if ((flags & TCP_ACKDATA) != 0) { conn->tcpstateflags = TCP_CLOSED; ninfo("TCP_LAST_ACK TCP state: TCP_CLOSED\n"); tcp_callback(dev, conn, TCP_CLOSE); } break; case TCP_FIN_WAIT_1: /* The application has closed the connection, but the remote host * hasn't closed its end yet. Thus we stay in the FIN_WAIT_1 state * until we receive a FIN from the remote. */ if (dev->d_len > 0) { net_incr32(conn->rcvseq, dev->d_len); } if ((tcp->flags & TCP_FIN) != 0) { if ((flags & TCP_ACKDATA) != 0 && conn->tx_unacked == 0) { conn->tcpstateflags = TCP_TIME_WAIT; conn->timer = 0; ninfo("TCP state: TCP_TIME_WAIT\n"); } else { conn->tcpstateflags = TCP_CLOSING; ninfo("TCP state: TCP_CLOSING\n"); } net_incr32(conn->rcvseq, 1); tcp_callback(dev, conn, TCP_CLOSE); tcp_send(dev, conn, TCP_ACK, tcpiplen); return; } else if ((flags & TCP_ACKDATA) != 0 && conn->tx_unacked == 0) { conn->tcpstateflags = TCP_FIN_WAIT_2; ninfo("TCP state: TCP_FIN_WAIT_2\n"); goto drop; } if (dev->d_len > 0) { tcp_send(dev, conn, TCP_ACK, tcpiplen); return; } goto drop; case TCP_FIN_WAIT_2: if (dev->d_len > 0) { net_incr32(conn->rcvseq, dev->d_len); } if ((tcp->flags & TCP_FIN) != 0) { conn->tcpstateflags = TCP_TIME_WAIT; conn->timer = 0; ninfo("TCP state: TCP_TIME_WAIT\n"); net_incr32(conn->rcvseq, 1); tcp_callback(dev, conn, TCP_CLOSE); tcp_send(dev, conn, TCP_ACK, tcpiplen); return; } if (dev->d_len > 0) { tcp_send(dev, conn, TCP_ACK, tcpiplen); return; } goto drop; case TCP_TIME_WAIT: tcp_send(dev, conn, TCP_ACK, tcpiplen); return; case TCP_CLOSING: if ((flags & TCP_ACKDATA) != 0) { conn->tcpstateflags = TCP_TIME_WAIT; conn->timer = 0; ninfo("TCP state: TCP_TIME_WAIT\n"); } default: break; } drop: dev->d_len = 0; } /**************************************************************************** * Public Functions ****************************************************************************/ /**************************************************************************** * Name: tcp_ipv4_input * * Description: * Handle incoming TCP input with IPv4 header * * Input Parameters: * dev - The device driver structure containing the received TCP packet. * * Returned Value: * None * * Assumptions: * Called from the Ethernet driver with the network stack locked * ****************************************************************************/ #ifdef CONFIG_NET_IPv4 void tcp_ipv4_input(FAR struct net_driver_s *dev) { FAR struct ipv4_hdr_s *ipv4 = IPv4BUF; uint16_t iphdrlen; /* Configure to receive an TCP IPv4 packet */ tcp_ipv4_select(dev); /* Get the IP header length (accounting for possible options). */ iphdrlen = (ipv4->vhl & IPv4_HLMASK) << 2; /* Then process in the TCP IPv4 input */ tcp_input(dev, PF_INET, iphdrlen); } #endif /**************************************************************************** * Name: tcp_ipv6_input * * Description: * Handle incoming TCP input with IPv4 header * * Input Parameters: * dev - The device driver structure containing the received TCP packet. * iplen - The size of the IPv6 header. This may be larger than * IPv6_HDRLEN the IPv6 header if IPv6 extension headers are * present. * * Returned Value: * None * * Assumptions: * Called from the Ethernet driver with the network stack locked * ****************************************************************************/ #ifdef CONFIG_NET_IPv6 void tcp_ipv6_input(FAR struct net_driver_s *dev, unsigned int iplen) { /* Configure to receive an TCP IPv6 packet */ tcp_ipv6_select(dev); /* Then process in the TCP IPv6 input */ tcp_input(dev, PF_INET6, iplen); } #endif #endif /* CONFIG_NET && CONFIG_NET_TCP */