/**************************************************************************** * net/neighbor/neighbor_out.c * * Copyright (C) 2015 Gregory Nutt. All rights reserved. * Author: Gregory Nutt * * 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. Neither the name NuttX nor the names of its contributors may be * used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "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 * COPYRIGHT OWNER OR CONTRIBUTORS 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 #include #include #include #include #include "route/route.h" #include "icmpv6/icmpv6.h" #include "neighbor/neighbor.h" /**************************************************************************** * Pre-processor Definitions ****************************************************************************/ #define ETHBUF ((struct eth_hdr_s *)dev->d_buf) #define IPv6BUF ((struct ipv6_hdr_s *)&dev->d_buf[NET_LL_HDRLEN(dev)]) /**************************************************************************** * Private Types ****************************************************************************/ /**************************************************************************** * Private Data ****************************************************************************/ /* Support for broadcast address */ static const struct ether_addr g_broadcast_ethaddr = { { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff } }; /* Support for IGMP 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) * * The following is the first three octects of the IGMP address: */ #ifdef CONFIG_NET_IGMP static const uint8_t g_multicast_ethaddr[3] = { 0x01, 0x00, 0x5e }; #endif /**************************************************************************** * Private Functions ****************************************************************************/ /**************************************************************************** * Public Functions ****************************************************************************/ /**************************************************************************** * Name: neighbor_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_out(FAR struct net_driver_s *dev) { FAR const struct neighbor_addr_s *naddr; FAR struct eth_hdr_s *eth = ETHBUF; FAR struct ipv6_hdr_s *ip = IPv6BUF; net_ipv6addr_t ipaddr; /* Skip sending Neighbor Solicitations when the frame to be transmitted was * written into a packet socket or if we are sending certain Neighbor * messages (solicitation, advertisement, echo request). */ 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 is a IPv6 multicast address. IPv6 * multicast addresses in IPv6 have the prefix ff00::/8 * * Bits 120-127: Prefix * Bits 116-119: Flags (1, 2, or 3 defined) * Bits 112-115: Scope * * REVISIT: Need to revisit IPv6 broadcast support. Broadcast * IP addresses are not used with IPv6; multicast is used instead. * Does this mean that all multicast address should go to the * broadcast Ethernet address? */ if ((ip->destipaddr[0] & HTONS(0xff00)) == HTONS(0xff00)) { memcpy(eth->dest, g_broadcast_ethaddr.ether_addr_octet, ETHER_ADDR_LEN); } #ifdef CONFIG_NET_IGMP /* Check if the destination address is a multicast address * * IPv6 multicast addresses are have the high-order octet of the * addresses=0xff (ff00::/8.) * * REVISIT: See comments above. How do we distinguish broadcast * from IGMP multicast? */ #warning Missing logic #endif else { /* Check if the destination address is on the local network. */ if (!net_ipv6addr_maskcmp(ip->destipaddr, dev->d_ipv6addr, dev->d_ipv6netmask)) { /* 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 */ naddr = neighbor_lookup(ipaddr); if (!naddr) { ninfo("IPv6 Neighbor solicitation for IPv6\n"); /* The destination address was not in our Neighbor Table, so we * overwrite the IPv6 packet with an ICMDv6 Neighbor Solicitation * message. */ icmpv6_solicit(dev, ipaddr); return; } /* Build an Ethernet header. */ memcpy(eth->dest, naddr->na_addr.ether_addr_octet, ETHER_ADDR_LEN); } /* Finish populating the Ethernet header */ memcpy(eth->src, dev->d_mac.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]); }