/**************************************************************************** * net/neighbor/neighbor_ethernet_out.c * * SPDX-License-Identifier: Apache-2.0 * * 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 "devif/devif.h" #include "route/route.h" #include "icmpv6/icmpv6.h" #include "neighbor/neighbor.h" /**************************************************************************** * Private Data ****************************************************************************/ /* Support for MLD multicast addresses. * * Well-known ethernet multicast address: * * ADDRESS TYPE USAGE * 01-00-0c-cc-cc-cc 0x0802 CDP (Cisco Discovery Protocol), VTP (Virtual * Trunking Protocol) * 01-00-0c-cc-cc-cd 0x0802 Cisco Shared Spanning Tree Protocol Address * 01-80-c2-00-00-00 0x0802 Spanning Tree Protocol (for bridges) IEEE 802.1D * 01-80-c2-00-00-02 0x0809 Ethernet OAM Protocol IEEE 802.3ah * 01-00-5e-xx-xx-xx 0x0800 IPv4 IGMP Multicast Address * 33-33-00-00-00-00 0x86DD IPv6 Neighbor Discovery * 33-33-xx-xx-xx-xx 0x86DD IPv6 Multicast Address (RFC3307) */ /**************************************************************************** * Private Functions ****************************************************************************/ /**************************************************************************** * Public Functions ****************************************************************************/ /**************************************************************************** * Name: neighbor_ethernet_out * * Description: * This function should be called before sending out an IPv6 packet. The * function checks the destination IPv6 address of the IPv6 packet to see * what Ethernet MAC address that should be used as a destination MAC * address on the Ethernet. * * If the destination IPv6 address is in the local network (determined * by logical ANDing of netmask and our IPv6 address), the function * checks the Neighbor Table to see if an entry for the destination IPv6 * address is found. If so, an Ethernet header is pre-pended at the * beginning of the packet and the function returns. * * If no Neighbor Table entry is found for the destination IPv6 address, * the packet in the d_buf is replaced by an ICMPv6 Neighbor Solicit * request packet for the IPv6 address. The IPv6 packet is dropped and * it is assumed that the higher level protocols (e.g., TCP) eventually * will retransmit the dropped packet. * * Upon return in either the case, a packet to be sent is present in the * d_buf buffer and the d_len field holds the length of the Ethernet * frame that should be transmitted. * ****************************************************************************/ void neighbor_ethernet_out(FAR struct net_driver_s *dev) { FAR struct eth_hdr_s *eth = ETHBUF; FAR struct ipv6_hdr_s *ip = IPv6BUF; struct neighbor_addr_s laddr; /* Skip sending Neighbor Solicitations when the frame to be transmitted was * written into a packet socket. */ if (IFF_IS_NOARP(dev->d_flags)) { /* Clear the indication and let the packet continue on its way. */ IFF_CLR_NOARP(dev->d_flags); return; } /* Find the destination IPv6 address in the Neighbor Table and construct * the Ethernet header. If the destination IPv6 address isn't on the local * network, we use the default router's IPv6 address instead. * * If no Neighbor Table entry is found, we overwrite the original IPv6 * packet with an Neighbor Solicitation Request for the IPv6 address. */ /* First check if destination isn't IPv6 multicast address. */ if (!net_is_addr_mcast(ip->destipaddr)) { net_ipv6addr_t ipaddr; /* Check if the destination address is on the local network. */ if (!NETDEV_V6ADDR_ONLINK(dev, ip->destipaddr)) { /* Destination address is not on the local network */ #ifdef CONFIG_NET_ROUTE /* We have a routing table.. find the correct router to use in * this case (or, as a fall-back, use the device's default router * address). We will use the router IPv6 address instead of the * destination address when determining the MAC address. */ netdev_ipv6_router(dev, ip->destipaddr, ipaddr); #else /* Use the device's default router IPv6 address instead of the * destination address when determining the MAC address. */ net_ipv6addr_copy(ipaddr, dev->d_ipv6draddr); #endif } else { /* Else, we use the destination IPv6 address. */ net_ipv6addr_copy(ipaddr, ip->destipaddr); } /* Check if we already have this destination address in the * Neighbor Table. */ if (neighbor_lookup(ipaddr, &laddr) < 0) { #ifdef CONFIG_NET_ICMPv6 ninfo("IPv6 Neighbor solicitation for IPv6\n"); /* The destination address was not in our Neighbor Table, so we * overwrite the IPv6 packet with an ICMPv6 Neighbor Solicitation * message. */ icmpv6_solicit(dev, ipaddr); #else /* What to do here? We need the laddr, but no way to get it. */ nerr("ERROR: IPv6 needs link layer address for ethernet.\n"); DEBUGPANIC(); return; #endif } } /* Build an Ethernet header. */ if (net_is_addr_mcast(ip->destipaddr)) { eth->dest[0] = eth->dest[1] = 0x33; memcpy(ð->dest[2], &ip->destipaddr[6], 4); } else { memcpy(eth->dest, laddr.u.na_ethernet.ether_addr_octet, ETHER_ADDR_LEN); } /* Finish populating the Ethernet header */ memcpy(eth->src, dev->d_mac.ether.ether_addr_octet, ETHER_ADDR_LEN); eth->type = HTONS(ETHTYPE_IP6); /* Add the size of the layer layer header to the total size of the * outgoing packet. */ dev->d_len += netdev_ipv6_hdrlen(dev); ninfo("Outgoing IPv6 Packet length: %d (%d)\n", dev->d_len, (ip->len[0] << 8) | ip->len[1]); }