/**************************************************************************** * net/sixlowpan/sixlowpan_tcpsend.c * * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. The * ASF licenses this file to you under the Apache License, Version 2.0 (the * "License"); you may not use this file except in compliance with the * License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the * License for the specific language governing permissions and limitations * under the License. * ****************************************************************************/ /**************************************************************************** * Included Files ****************************************************************************/ #include #include #include #include #include #include #include #include #include #include #include "netdev/netdev.h" #include "devif/devif.h" #include "socket/socket.h" #include "inet/inet.h" #include "icmpv6/icmpv6.h" #include "tcp/tcp.h" #include "utils/utils.h" #include "sixlowpan/sixlowpan_internal.h" #if defined(CONFIG_NET_6LOWPAN) && defined(CONFIG_NET_TCP) /**************************************************************************** * Pre-processor Definitions ****************************************************************************/ /* Buffer access helpers */ #define TCPBUF(dev) ((FAR struct tcp_hdr_s *)(&(dev)->d_buf[IPv6_HDRLEN])) /**************************************************************************** * Pre-processor Definitions ****************************************************************************/ /* These are temporary stubs. Something like this would be needed to * monitor the health of a IPv6 neighbor. */ #define neighbor_reachable(dev) #define neighbor_notreachable(dev) /**************************************************************************** * Private Types ****************************************************************************/ /* This is the state data provided to the send event handler. No actions * can be taken until the until we receive the TX poll, then we can call * sixlowpan_queue_frames() with this data strurcture. */ struct sixlowpan_send_s { FAR struct tcp_conn_s *s_conn; /* Internal connect reference */ FAR struct devif_callback_s *s_cb; /* Reference to callback * instance */ sem_t s_waitsem; /* Supports waiting for * driver events */ int s_result; /* The result of the transfer */ FAR const struct netdev_varaddr_s *s_destmac; /* Destination MAC address */ FAR const uint8_t *s_buf; /* Data to send */ size_t s_buflen; /* Length of data in buf */ ssize_t s_sent; /* The number of bytes sent */ uint32_t s_isn; /* Initial sequence number */ uint32_t s_acked; /* The number of bytes acked */ }; /**************************************************************************** * Private Functions ****************************************************************************/ /**************************************************************************** * Name: sixlowpan_tcp_chksum * * Description: * Perform the checksum calcaultion over the IPv6, protocol headers, and * data payload as necessary. * * Input Parameters: * ipv6tcp - A reference to a structure containing the IPv6 and TCP * headers. * buf - The beginning of the payload data * buflen - The length of the payload data. * * Returned Value: * The calculated checksum * ****************************************************************************/ static uint16_t sixlowpan_tcp_chksum(FAR const struct ipv6tcp_hdr_s *ipv6tcp, FAR const uint8_t *buf, uint16_t buflen) { uint16_t upperlen; uint16_t tcplen; uint16_t sum; /* The length reported in the IPv6 header is the length of the payload * that follows the header. */ upperlen = ((uint16_t)ipv6tcp->ipv6.len[0] << 8) + ipv6tcp->ipv6.len[1]; /* Verify some minimal assumptions */ if (upperlen > CONFIG_NET_6LOWPAN_PKTSIZE) { return 0; } /* The checksum is calculated starting with a pseudo-header of IPv6 header * fields according to the IPv6 standard, which consists of the source * and destination addresses, the packet length and the next header field. */ sum = upperlen + ipv6tcp->ipv6.proto; /* Sum IP source and destination addresses. */ sum = chksum(sum, (FAR uint8_t *)ipv6tcp->ipv6.srcipaddr, 2 * sizeof(net_ipv6addr_t)); /* Sum the TCP header * * The TCP header length is encoded in the top 4 bits of the tcpoffset * field (in units of 32-bit words). */ tcplen = ((uint16_t)ipv6tcp->tcp.tcpoffset >> 4) << 2; sum = chksum(sum, (FAR uint8_t *)&ipv6tcp->tcp, tcplen); /* Sum payload data. */ sum = chksum(sum, buf, buflen); return (sum == 0) ? 0xffff : HTONS(sum); } /**************************************************************************** * Name: sixlowpan_tcp_header * * Description: * sixlowpan_tcp_header() will construct the IPv6 and TCP headers * * Input Parameters: * conn - An instance of the TCP connection structure. * dev - The network device that will route the packet * buf - Data to send * bulen - Length of data to send * ipv6tcp - The location to save the IPv6 + TCP header * * Returned Value: * Zero (OK) is returned on success; a negated errno value is returned on * failure. * * Assumptions: * Called with the network locked. * ****************************************************************************/ static int sixlowpan_tcp_header(FAR struct tcp_conn_s *conn, FAR struct net_driver_s *dev, FAR const void *buf, size_t buflen, FAR struct ipv6tcp_hdr_s *ipv6tcp) { uint16_t iplen; /* Initialize the IPv6/TCP headers */ ipv6tcp->ipv6.vtc = 0x60; ipv6tcp->ipv6.tcf = 0x00; ipv6tcp->ipv6.flow = 0x00; ipv6tcp->ipv6.proto = IP_PROTO_TCP; ipv6tcp->ipv6.ttl = IP_TTL_DEFAULT; /* The IPv6 header length field does not include the size of IPv6 IP * header. */ iplen = buflen + TCP_HDRLEN; ipv6tcp->ipv6.len[0] = (iplen >> 8); ipv6tcp->ipv6.len[1] = (iplen & 0xff); /* Copy the source and destination addresses */ net_ipv6addr_hdrcopy(ipv6tcp->ipv6.destipaddr, conn->u.ipv6.raddr); if (!net_ipv6addr_cmp(conn->u.ipv6.laddr, g_ipv6_unspecaddr)) { net_ipv6addr_hdrcopy(ipv6tcp->ipv6.srcipaddr, conn->u.ipv6.laddr); } else { net_ipv6addr_hdrcopy(ipv6tcp->ipv6.srcipaddr, dev->d_ipv6addr); } ninfo("IPv6 length: %d\n", ((int)ipv6tcp->ipv6.len[0] << 8) + ipv6tcp->ipv6.len[1]); #ifdef CONFIG_NET_STATISTICS g_netstats.ipv6.sent++; #endif /* Initialize the TCP header */ ipv6tcp->tcp.srcport = conn->lport; /* Local port */ ipv6tcp->tcp.destport = conn->rport; /* Connected remote port */ ipv6tcp->tcp.tcpoffset = (TCP_HDRLEN / 4) << 4; /* No optdata */ ipv6tcp->tcp.flags = TCP_ACK | TCP_PSH; /* No urgent data */ ipv6tcp->tcp.urgp[0] = 0; /* No urgent data */ ipv6tcp->tcp.urgp[1] = 0; /* Set the sequency number information. * * REVISIT: There is currently no wait for the data to be ACKed and, * hence, no mechanism to retransmit the packet. */ memcpy(ipv6tcp->tcp.ackno, conn->rcvseq, 4); /* ACK number */ memcpy(ipv6tcp->tcp.seqno, conn->sndseq, 4); /* Sequence number */ /* Set the TCP window */ if (conn->tcpstateflags & TCP_STOPPED) { /* If the connection has issued TCP_STOPPED, we advertise a zero * window so that the remote host will stop sending data. */ ipv6tcp->tcp.wnd[0] = 0; ipv6tcp->tcp.wnd[1] = 0; } else { /* Update the TCP received window based on I/O buffer availability */ uint32_t rcvseq = tcp_getsequence(conn->rcvseq); uint32_t recvwndo = tcp_get_recvwindow(dev, conn); /* Set the TCP Window */ ipv6tcp->tcp.wnd[0] = recvwndo >> 8; ipv6tcp->tcp.wnd[1] = recvwndo & 0xff; /* Update the Receiver Window */ conn->rcv_adv = rcvseq + recvwndo; } /* Calculate TCP checksum. */ ipv6tcp->tcp.tcpchksum = 0; ipv6tcp->tcp.tcpchksum = ~sixlowpan_tcp_chksum(ipv6tcp, buf, buflen); ninfo("Outgoing TCP packet length: %d bytes\n", iplen + IPv6_HDRLEN); return OK; } /**************************************************************************** * Name: tcp_send_eventhandler * * Description: * This function is called with the network locked to perform the actual * TCP send operation when polled by the lower, device interfacing layer. * * Input Parameters: * dev - The structure of the network driver that generated the event. * pvpriv - The event handler's private data argument * flags - Set of events describing why the callback was invoked * * Returned Value: * None * * Assumptions: * The network is locked. * ****************************************************************************/ static uint16_t tcp_send_eventhandler(FAR struct net_driver_s *dev, FAR void *pvpriv, uint16_t flags) { FAR struct sixlowpan_send_s *sinfo = pvpriv; FAR struct tcp_conn_s *conn = sinfo->s_conn; struct ipv6tcp_hdr_s ipv6tcp; int ret; /* Verify that this is an IEEE802.15.4 network driver. */ if (dev->d_lltype != NET_LL_IEEE802154 && dev->d_lltype != NET_LL_PKTRADIO) { ninfo("Not a compatible network device\n"); return flags; } /* Check if the IEEE802.15.4 network driver went down */ if ((flags & NETDEV_DOWN) != 0) { nwarn("WARNING: Device is down\n"); sinfo->s_result = -ENOTCONN; goto end_wait; } /* The TCP socket is connected 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) { ninfo("Not the connected device\n"); return flags; } ninfo("flags: %04x acked: %" PRIu32 " sent: %zu\n", flags, sinfo->s_acked, sinfo->s_sent); /* If this packet contains an acknowledgement, then update the count of * acknowledged bytes. */ if ((flags & TCP_ACKDATA) != 0) { FAR struct tcp_hdr_s *tcp = TCPBUF(dev); /* The current acknowledgement number number is the (relative) offset * of the of the next byte needed by the receiver. The s_isn is the * offset of the first byte to send to the receiver. The difference * is the number of bytes to be acknowledged. */ sinfo->s_acked = tcp_getsequence(tcp->ackno) - sinfo->s_isn; ninfo("ACK: acked=%" PRId32 " sent=%zd buflen=%zd\n", sinfo->s_acked, sinfo->s_sent, sinfo->s_buflen); /* Have all of the bytes in the buffer been sent and acknowledged? */ if (sinfo->s_acked >= sinfo->s_buflen) { /* Yes. Then sinfo->s_buflen should hold the number of bytes * actually sent. */ sinfo->s_result = sinfo->s_sent; goto end_wait; } /* No.. fall through to send more data if necessary */ } /* Check if we are being asked to retransmit data */ else if ((flags & TCP_REXMIT) != 0) { /* Yes.. in this case, reset the number of bytes that have been sent * to the number of bytes that have been ACKed. */ sinfo->s_sent = sinfo->s_acked; /* Fall through to re-send data from the last that was ACKed */ } /* Check for a loss of connection */ else if ((flags & TCP_DISCONN_EVENTS) != 0) { nwarn("WARNING: Lost connection\n"); /* We could get here recursively through the callback actions of * tcp_lost_connection(). So don't repeat that action if we have * already been disconnected. */ if (_SS_ISCONNECTED(conn->sconn.s_flags)) { /* Report the disconnection event to all socket clones */ tcp_lost_connection(conn, sinfo->s_cb, flags); } /* Report not connected to the sender */ sinfo->s_result = -ENOTCONN; goto end_wait; } /* Check if the outgoing packet is available (it may have been claimed * by a sendto event handler serving a different thread). */ #if 0 /* We can't really support multiple senders on the same TCP socket */ else if (dev->d_sndlen > 0) { /* Another thread has beat us sending data, wait for the next poll */ return flags; } #endif /* We get here if (1) not all of the data has been ACKed, (2) we have been * asked to retransmit data, (3) the connection is still healthy, and (4) * the outgoing packet is available for our use. In this case, we are * now free to send more data to receiver -- UNLESS the buffer contains * unprocessed incoming data. In that event, we will have to wait for the * next polling cycle. */ if ((flags & WPAN_NEWDATA) == 0 && sinfo->s_sent < sinfo->s_buflen) { uint32_t seqno; uint16_t winleft; uint16_t sndlen; /* Get the amount of TCP payload data that we can send in the next * packet. */ sndlen = sinfo->s_buflen - sinfo->s_sent; if (sndlen > conn->mss) { sndlen = conn->mss; } winleft = conn->snd_wnd - sinfo->s_sent + sinfo->s_acked; if (sndlen > winleft) { sndlen = winleft; } ninfo("s_buflen=%zu s_sent=%zu mss=%u snd_wnd=%u sndlen=%d\n", sinfo->s_buflen, sinfo->s_sent, conn->mss, conn->snd_wnd, sndlen); if (sndlen > 0) { /* Set the sequence number for this packet. NOTE: The network * updates sndseq on receipt of ACK *before* this function is * called. In that case sndseq will point to the next * unacknowledged byte (which might have already been sent). We * will overwrite the value of sndseq here before the packet is * sent. */ seqno = sinfo->s_sent + sinfo->s_isn; ninfo("Sending: sndseq %08" PRIx32 "->%08" PRIx32 "\n", tcp_getsequence(conn->sndseq), seqno); tcp_setsequence(conn->sndseq, seqno); /* Create the IPv6 + TCP header */ ret = sixlowpan_tcp_header(conn, dev, &sinfo->s_buf[sinfo->s_sent], sndlen, &ipv6tcp); if (ret < 0) { nerr("ERROR: sixlowpan_tcp_header failed: %d\n", ret); sinfo->s_result = ret; goto end_wait; } /* Transfer the frame list to the IEEE802.15.4 MAC device */ ret = sixlowpan_queue_frames((FAR struct radio_driver_s *)dev, &ipv6tcp.ipv6, &sinfo->s_buf[sinfo->s_sent], sndlen, sinfo->s_destmac); if (ret < 0) { nerr("ERROR: sixlowpan_queue_frames failed: %d\n", ret); sinfo->s_result = ret; goto end_wait; } /* Increment the count of bytes sent, the number of unacked bytes, * and the total count of TCP packets sent. * * NOTE: tcp_appsend() normally increments conn->tx_unacked based * on the value of dev->d_sndlen. However, dev->d_len is always * zero for 6LoWPAN since it does not send via the dev->d_buf * but, rather, uses a backdoor frame interface with the IEEE * 802.15.4 MAC. */ sinfo->s_sent += sndlen; conn->tx_unacked += sndlen; #ifdef CONFIG_NET_TCP_WRITE_BUFFERS /* For compatibility with buffered send logic */ conn->sndseq_max = tcp_addsequence(conn->sndseq, conn->tx_unacked); #endif #ifdef CONFIG_NET_STATISTICS g_netstats.tcp.sent++; #endif ninfo("Sent: acked=%" PRId32 " sent=%zd " "buflen=%zd tx_unacked=%" PRId32 "\n", sinfo->s_acked, sinfo->s_sent, sinfo->s_buflen, (uint32_t)conn->tx_unacked); } } /* Continue waiting */ return flags; end_wait: /* Do not allow any further callbacks */ sinfo->s_cb->flags = 0; sinfo->s_cb->priv = NULL; sinfo->s_cb->event = NULL; /* There are no outstanding, unacknowledged bytes */ conn->tx_unacked = 0; /* Wake up the waiting thread */ nxsem_post(&sinfo->s_waitsem); return flags; } /**************************************************************************** * Name: sixlowpan_send_packet * * Description: * Process an outgoing TCP packet. Takes an IP packet and formats it to * be sent on an 802.15.4 network using 6lowpan. Called from common TCP * send logic. * * The payload data is in the caller 'buf' and is of length 'buflen'. * Compressed headers will be added and if necessary the packet is * fragmented. The resulting packet/fragments are submitted to the MAC * via the network driver r_req_data method. * * Input Parameters: * psock - An instance of the internal socket structure. * dev - The IEEE802.15.4 MAC network driver interface. * conn - TCP connection structure * buf - Data to send * len - Length of data to send * destmac - The IEEE802.15.4 MAC address of the destination * timeout - Send timeout in milliseconds * * Returned Value: * Ok is returned on success; Otherwise a negated errno value is returned. * This function is expected to fail if the driver is not an IEEE802.15.4 * MAC network driver. In that case, the logic will fall back to normal * IPv4/IPv6 formatting. * * Assumptions: * Called with the network locked. * ****************************************************************************/ static int sixlowpan_send_packet(FAR struct socket *psock, FAR struct net_driver_s *dev, FAR struct tcp_conn_s *conn, FAR const uint8_t *buf, size_t len, FAR const struct netdev_varaddr_s *destmac, unsigned int timeout) { struct sixlowpan_send_s sinfo; ninfo("len=%lu timeout=%u\n", (unsigned long)len, timeout); DEBUGASSERT(psock != NULL && dev != NULL && conn != NULL && buf != NULL && destmac != NULL); memset(&sinfo, 0, sizeof(struct sixlowpan_send_s)); net_lock(); if (len > 0) { /* Allocate resources to receive a callback. * * The second parameter is NULL meaning that we can get only * device related events, no connect-related events. */ sinfo.s_cb = tcp_callback_alloc(conn); if (sinfo.s_cb != NULL) { int ret; /* Initialize the send state structure */ nxsem_init(&sinfo.s_waitsem, 0, 0); sinfo.s_conn = conn; sinfo.s_result = -EBUSY; sinfo.s_destmac = destmac; sinfo.s_buf = buf; sinfo.s_buflen = len; /* Set up the initial sequence number */ sinfo.s_isn = tcp_getsequence(conn->sndseq); /* Set up the callback in the connection */ sinfo.s_cb->flags = (NETDEV_DOWN | TCP_ACKDATA | TCP_REXMIT | TCP_DISCONN_EVENTS | WPAN_POLL); sinfo.s_cb->priv = (FAR void *)&sinfo; sinfo.s_cb->event = tcp_send_eventhandler; /* There is no outstanding, unacknowledged data after this * initial sequence number. */ conn->tx_unacked = 0; /* Notify the IEEE802.15.4 MAC that we have data to send. */ netdev_txnotify_dev(dev); /* Wait for the send to complete or an error to occur. * net_sem_timedwait will also terminate if a signal is received. */ ninfo("Wait for send complete\n"); for (; ; ) { uint32_t acked = sinfo.s_acked; ret = net_sem_timedwait(&sinfo.s_waitsem, timeout); if (ret != -ETIMEDOUT || acked == sinfo.s_acked) { if (ret == -ETIMEDOUT) { ret = -EAGAIN; } break; /* Timeout without any progress */ } } if (ret < 0) { sinfo.s_result = ret; } /* Make sure that no further events are processed */ tcp_callback_free(conn, sinfo.s_cb); } } nxsem_destroy(&sinfo.s_waitsem); net_unlock(); return (sinfo.s_result < 0 ? sinfo.s_result : len); } /**************************************************************************** * Public Functions ****************************************************************************/ /**************************************************************************** * Name: psock_6lowpan_tcp_send * * Description: * psock_6lowpan_tcp_send() call may be used only when the TCP socket is * in a connected state (so that the intended recipient is known). * * Input Parameters: * psock - An instance of the internal socket structure. * buf - Data to send * bulen - Length of data to send * * Returned Value: * On success, returns the number of characters sent. On error, * -1 is returned, and errno is set appropriately. Returned error numbers * must be consistent with definition of errors reported by send() or * sendto(). * * Assumptions: * Called with the network locked. * ****************************************************************************/ ssize_t psock_6lowpan_tcp_send(FAR struct socket *psock, FAR const void *buf, size_t buflen) { FAR struct tcp_conn_s *conn; FAR struct net_driver_s *dev; struct netdev_varaddr_s destmac; int ret; ninfo("buflen %lu\n", (unsigned long)buflen); sixlowpan_dumpbuffer("Outgoing TCP payload", buf, buflen); DEBUGASSERT(psock != NULL && psock->s_conn != NULL); DEBUGASSERT(psock->s_type == SOCK_STREAM); /* Make sure that this is a valid socket */ if (psock == NULL || psock->s_conn == NULL) { nerr("ERROR: Invalid socket\n"); return (ssize_t)-EBADF; } /* Get the underlying TCP connection structure */ conn = psock->s_conn; /* Make sure that this is a connected TCP socket */ if (psock->s_type != SOCK_STREAM || !_SS_ISCONNECTED(conn->sconn.s_flags)) { nerr("ERROR: Not connected\n"); return (ssize_t)-ENOTCONN; } #ifdef CONFIG_NET_IPv4 /* Ignore if not IPv6 domain */ if (conn->domain != PF_INET6) { nwarn("WARNING: Not IPv6\n"); return (ssize_t)-EPROTOTYPE; } #endif /* Route outgoing message to the correct device */ dev = netdev_findby_ripv6addr(conn->u.ipv6.laddr, conn->u.ipv6.raddr); if (dev == NULL) { nwarn("WARNING: Not routable\n"); return (ssize_t)-ENETUNREACH; } /* Some network devices support different link layer protocols. * Check if this device has the hooks to support 6LoWPAN. */ if (dev->d_lltype != NET_LL_IEEE802154 && dev->d_lltype != NET_LL_PKTRADIO) { nwarn("WARNING: Not a compatible network device\n"); return (ssize_t)-ENONET; } #ifdef CONFIG_NET_ICMPv6_NEIGHBOR /* Make sure that the IP address mapping is in the Neighbor Table */ ret = icmpv6_neighbor(dev, conn->u.ipv6.raddr); if (ret < 0) { nerr("ERROR: Not reachable\n"); return (ssize_t)-ENETUNREACH; } #endif /* Get the IEEE 802.15.4 MAC address of the next hop. */ ret = sixlowpan_nexthopaddr((FAR struct radio_driver_s *)dev, conn->u.ipv6.raddr, &destmac); if (ret < 0) { nerr("ERROR: Failed to get dest MAC address: %d\n", ret); return (ssize_t)ret; } /* Send the TCP packets, breaking down the potential large user buffer * into smaller packets that can be reassembled in the allocated MTU * packet buffer. */ ret = sixlowpan_send_packet(psock, dev, conn, buf, buflen, &destmac, _SO_TIMEOUT(conn->sconn.s_sndtimeo)); if (ret < 0) { nerr("ERROR: sixlowpan_send_packet() failed: %d\n", ret); return (ssize_t)ret; } return (ssize_t)buflen; } /**************************************************************************** * Name: sixlowpan_tcp_send * * Description: * TCP output comes through three different mechansims. Either from: * * 1. TCP socket output. For the case of TCP output to an * IEEE802.15.4, the TCP output is caught in the socket * send()/sendto() logic and and redirected to psock_6lowpan_tcp_send(). * 2. TCP output from the TCP state machine. That will occur * during TCP packet processing by the TCP state meachine. * 3. TCP output resulting from TX or timer polling * * Cases 2 and 3 will be handled here. Logic in ipv6_tcp_input(), * and devif_poll() detect if (1) an attempt to return with * d_len > 0 and (2) that the device is an IEEE802.15.4 MAC network * driver. Under those conditions, this function will be called to create * the IEEE80215.4 frames. * * Input Parameters: * dev - The network device containing the packet to be sent. * fwddev - The network device used to send the data. This will be the * same device except for the IP forwarding case where packets * are sent across devices. * ipv6 - A pointer to the IPv6 header in dev->d_buf which lies AFTER * the L1 header. NOTE: dev->d_len must have been decremented * by the size of any preceding MAC header. * * Returned Value: * None * * Assumptions: * Called with the network locked. * ****************************************************************************/ void sixlowpan_tcp_send(FAR struct net_driver_s *dev, FAR struct net_driver_s *fwddev, FAR struct ipv6_hdr_s *ipv6) { DEBUGASSERT(dev != NULL && dev->d_len > 0 && fwddev != NULL); /* Double check */ ninfo("d_len %u\n", dev->d_len); sixlowpan_dumpbuffer("Outgoing TCP packet", (FAR const uint8_t *)ipv6, dev->d_len); if (dev != NULL && dev->d_len > 0 && fwddev != NULL) { FAR struct ipv6tcp_hdr_s *ipv6hdr; /* The IPv6 header followed by a TCP headers should lie at the * beginning of d_buf since there is no link layer protocol header * and the TCP state machine should only response with TCP packets. */ ipv6hdr = (FAR struct ipv6tcp_hdr_s *)ipv6; /* The TCP data payload should follow the IPv6 header plus the * protocol header. */ if (ipv6hdr->ipv6.proto != IP_PROTO_TCP) { nwarn("WARNING: Expected TCP prototype: %u vs %u\n", ipv6hdr->ipv6.proto, IP_PROTO_TCP); } else { struct netdev_varaddr_s destmac; FAR uint8_t *buf; uint16_t hdrlen; uint16_t buflen; int ret; /* Get the IEEE 802.15.4 MAC address of the next hop. */ ret = sixlowpan_nexthopaddr((FAR struct radio_driver_s *)fwddev, ipv6hdr->ipv6.destipaddr, &destmac); if (ret < 0) { nerr("ERROR: Failed to get dest MAC address: %d\n", ret); goto drop; } /* Get the IPv6 + TCP combined header length. The size of the TCP * header is encoded in the top 4 bits of the tcpoffset field (in * units of 32-bit words). */ hdrlen = IPv6_HDRLEN + (((uint16_t)ipv6hdr->tcp.tcpoffset >> 4) << 2); /* Drop the packet if the buffer length is less than this. */ if (hdrlen > dev->d_len) { nwarn("WARNING: Dropping small TCP packet: %u < %u\n", dev->d_len, hdrlen); } else { /* Convert the outgoing packet into a frame list. */ buf = (FAR uint8_t *)ipv6 + hdrlen; buflen = dev->d_len - hdrlen; sixlowpan_queue_frames( (FAR struct radio_driver_s *)fwddev, &ipv6hdr->ipv6, buf, buflen, &destmac); } } } drop: dev->d_len = 0; } #endif /* CONFIG_NET_6LOWPAN && CONFIG_NET_TCP */