207 lines
7.2 KiB
C
207 lines
7.2 KiB
C
/****************************************************************************
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* net/neighbor/neighbor_ethernet_out.c
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <string.h>
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#include <assert.h>
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#include <debug.h>
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#include <nuttx/net/ethernet.h>
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#include <nuttx/net/ip.h>
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#include <nuttx/net/netdev.h>
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#include <nuttx/net/neighbor.h>
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#include "route/route.h"
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#include "icmpv6/icmpv6.h"
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#include "neighbor/neighbor.h"
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/****************************************************************************
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* Private Data
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****************************************************************************/
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/* Support for MLD multicast addresses.
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*
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* Well-known ethernet multicast address:
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*
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* ADDRESS TYPE USAGE
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* 01-00-0c-cc-cc-cc 0x0802 CDP (Cisco Discovery Protocol), VTP (Virtual
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* Trunking Protocol)
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* 01-00-0c-cc-cc-cd 0x0802 Cisco Shared Spanning Tree Protocol Address
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* 01-80-c2-00-00-00 0x0802 Spanning Tree Protocol (for bridges) IEEE 802.1D
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* 01-80-c2-00-00-02 0x0809 Ethernet OAM Protocol IEEE 802.3ah
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* 01-00-5e-xx-xx-xx 0x0800 IPv4 IGMP Multicast Address
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* 33-33-00-00-00-00 0x86DD IPv6 Neighbor Discovery
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* 33-33-xx-xx-xx-xx 0x86DD IPv6 Multicast Address (RFC3307)
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*/
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: neighbor_ethernet_out
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*
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* Description:
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* This function should be called before sending out an IPv6 packet. The
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* function checks the destination IPv6 address of the IPv6 packet to see
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* what Ethernet MAC address that should be used as a destination MAC
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* address on the Ethernet.
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*
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* If the destination IPv6 address is in the local network (determined
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* by logical ANDing of netmask and our IPv6 address), the function
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* checks the Neighbor Table to see if an entry for the destination IPv6
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* address is found. If so, an Ethernet header is pre-pended at the
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* beginning of the packet and the function returns.
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*
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* If no Neighbor Table entry is found for the destination IPv6 address,
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* the packet in the d_buf is replaced by an ICMPv6 Neighbor Solicit
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* request packet for the IPv6 address. The IPv6 packet is dropped and
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* it is assumed that the higher level protocols (e.g., TCP) eventually
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* will retransmit the dropped packet.
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*
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* Upon return in either the case, a packet to be sent is present in the
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* d_buf buffer and the d_len field holds the length of the Ethernet
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* frame that should be transmitted.
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*
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****************************************************************************/
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void neighbor_ethernet_out(FAR struct net_driver_s *dev)
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{
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FAR struct eth_hdr_s *eth = ETHBUF;
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FAR struct ipv6_hdr_s *ip = IPv6BUF;
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struct neighbor_addr_s laddr;
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/* Skip sending Neighbor Solicitations when the frame to be transmitted was
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* written into a packet socket.
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*/
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if (IFF_IS_NOARP(dev->d_flags))
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{
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/* Clear the indication and let the packet continue on its way. */
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IFF_CLR_NOARP(dev->d_flags);
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return;
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}
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/* Find the destination IPv6 address in the Neighbor Table and construct
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* the Ethernet header. If the destination IPv6 address isn't on the local
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* network, we use the default router's IPv6 address instead.
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*
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* If no Neighbor Table entry is found, we overwrite the original IPv6
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* packet with an Neighbor Solicitation Request for the IPv6 address.
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*/
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/* First check if destination isn't IPv6 multicast address. */
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if (!net_is_addr_mcast(ip->destipaddr))
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{
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net_ipv6addr_t ipaddr;
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/* Check if the destination address is on the local network. */
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if (!net_ipv6addr_maskcmp(ip->destipaddr, dev->d_ipv6addr,
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dev->d_ipv6netmask))
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{
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/* Destination address is not on the local network */
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#ifdef CONFIG_NET_ROUTE
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/* We have a routing table.. find the correct router to use in
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* this case (or, as a fall-back, use the device's default router
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* address). We will use the router IPv6 address instead of the
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* destination address when determining the MAC address.
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*/
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netdev_ipv6_router(dev, ip->destipaddr, ipaddr);
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#else
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/* Use the device's default router IPv6 address instead of the
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* destination address when determining the MAC address.
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*/
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net_ipv6addr_copy(ipaddr, dev->d_ipv6draddr);
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#endif
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}
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else
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{
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/* Else, we use the destination IPv6 address. */
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net_ipv6addr_copy(ipaddr, ip->destipaddr);
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}
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/* Check if we already have this destination address in the
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* Neighbor Table.
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*/
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if (neighbor_lookup(ipaddr, &laddr) < 0)
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{
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#ifdef CONFIG_NET_ICMPv6
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ninfo("IPv6 Neighbor solicitation for IPv6\n");
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/* The destination address was not in our Neighbor Table, so we
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* overwrite the IPv6 packet with an ICMPv6 Neighbor Solicitation
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* message.
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*/
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icmpv6_solicit(dev, ipaddr);
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#else
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/* What to do here? We need the laddr, but no way to get it. */
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nerr("ERROR: IPv6 needs link layer address for ethernet.\n");
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DEBUGPANIC();
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return;
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#endif
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}
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}
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/* Build an Ethernet header. */
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if (net_is_addr_mcast(ip->destipaddr))
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{
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eth->dest[0] = eth->dest[1] = 0x33;
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memcpy(ð->dest[2], &ip->destipaddr[6], 4);
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}
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else
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{
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memcpy(eth->dest, laddr.u.na_ethernet.ether_addr_octet,
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ETHER_ADDR_LEN);
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}
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/* Finish populating the Ethernet header */
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memcpy(eth->src, dev->d_mac.ether.ether_addr_octet, ETHER_ADDR_LEN);
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eth->type = HTONS(ETHTYPE_IP6);
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/* Add the size of the layer layer header to the total size of the
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* outgoing packet.
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*/
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dev->d_len += netdev_ipv6_hdrlen(dev);
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ninfo("Outgoing IPv6 Packet length: %d (%d)\n",
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dev->d_len, (ip->len[0] << 8) | ip->len[1]);
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}
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