/**************************************************************************** * net/arp/arp_out.c * * Copyright (C) 2007-2011, 2014 Gregory Nutt. All rights reserved. * Author: Gregory Nutt * * Based on uIP which also has a BSD style license: * * Author: Adam Dunkels * Copyright (c) 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 #include #include #include #include #include "arp/arp.h" #ifdef CONFIG_NET_ARP /**************************************************************************** * Pre-processor Definitions ****************************************************************************/ #define ETHBUF ((struct eth_hdr_s *)&dev->d_buf[0]) #define ARPBUF ((struct arp_hdr_s *)&dev->d_buf[NET_LL_HDRLEN]) #define IPBUF ((struct arp_iphdr_s *)&dev->d_buf[NET_LL_HDRLEN]) /**************************************************************************** * Private Types ****************************************************************************/ /**************************************************************************** * Private Data ****************************************************************************/ /* Support for broadcast address */ static const struct ether_addr g_broadcast_ethaddr = {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff}}; static const uint16_t g_broadcast_ipaddr[2] = {0xffff, 0xffff}; /* 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: */ #if defined(CONFIG_NET_IGMP) && !defined(CONFIG_NET_IPv6) static const uint8_t g_multicast_ethaddr[3] = {0x01, 0x00, 0x5e}; #endif /**************************************************************************** * Private Functions ****************************************************************************/ /**************************************************************************** * Public Functions ****************************************************************************/ /**************************************************************************** * Name: arp_out * * Description: * This function should be called before sending out an IP packet. The * function checks the destination IP address of the IP packet to see * what Ethernet MAC address that should be used as a destination MAC * address on the Ethernet. * * If the destination IP address is in the local network (determined * by logical ANDing of netmask and our IP address), the function * checks the ARP cache to see if an entry for the destination IP * address is found. If so, an Ethernet header is pre-pended at the * beginning of the packet and the function returns. * * If no ARP cache entry is found for the destination IP address, the * packet in the d_buf[] is replaced by an ARP request packet for the * IP address. The IP 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 arp_out(FAR struct net_driver_s *dev) { FAR const struct arp_entry *tabptr = NULL; FAR struct eth_hdr_s *peth = ETHBUF; FAR struct arp_iphdr_s *pip = IPBUF; in_addr_t ipaddr; in_addr_t destipaddr; #if defined(CONFIG_NET_PKT) || defined(CONFIG_NET_ARP_SEND) /* Skip sending ARP requests when the frame to be transmitted was * written into a packet socket. */ if ((dev->d_flags & IFF_NOARP) != 0) { /* Clear the indication and let the packet continue on its way. */ dev->d_flags &= ~IFF_NOARP; return; } #endif /* Find the destination IP address in the ARP table and construct * the Ethernet header. If the destination IP address isn't on the * local network, we use the default router's IP address instead. * * If not ARP table entry is found, we overwrite the original IP * packet with an ARP request for the IP address. */ /* First check if destination is a local broadcast. */ if (net_ipaddr_hdrcmp(pip->eh_destipaddr, g_broadcast_ipaddr)) { memcpy(peth->dest, g_broadcast_ethaddr.ether_addr_octet, ETHER_ADDR_LEN); } #if defined(CONFIG_NET_IGMP) && !defined(CONFIG_NET_IPv6) /* Check if the destination address is a multicast address * * - IPv4: multicast addresses lie in the class D group -- The address range * 224.0.0.0 to 239.255.255.255 (224.0.0.0/4) * * - IPv6 multicast addresses are have the high-order octet of the * addresses=0xff (ff00::/8.) */ else if (NTOHS(pip->eh_destipaddr[0]) >= 0xe000 && NTOHS(pip->eh_destipaddr[0]) <= 0xefff) { /* Build the well-known IPv4 IGMP Ethernet address. The first * three bytes are fixed; the final three variable come from the * last three bytes of the IP address. */ FAR const uint8_t *ip = ((uint8_t*)pip->eh_destipaddr) + 1; memcpy(peth->dest, g_multicast_ethaddr, 3); memcpy(&peth->dest[3], ip, 3); } #endif else { /* Check if the destination address is on the local network. */ destipaddr = net_ip4addr_conv32(pip->eh_destipaddr); if (!net_ipaddr_maskcmp(destipaddr, dev->d_ipaddr, dev->d_netmask)) { /* 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 IP address instead of the * destination address when determining the MAC address. */ netdev_router(dev, destipaddr, &ipaddr); #else /* Use the device's default router IP address instead of the * destination address when determining the MAC address. */ net_ipaddr_copy(ipaddr, dev->d_draddr); #endif } else { /* Else, we use the destination IP address. */ net_ipaddr_copy(ipaddr, destipaddr); } /* Check if we already have this destination address in the ARP table */ tabptr = arp_find(ipaddr); if (!tabptr) { nllvdbg("ARP request for IP %08lx\n", (unsigned long)ipaddr); /* The destination address was not in our ARP table, so we * overwrite the IP packet with an ARP request. */ arp_format(dev, ipaddr); arp_dump(ARPBUF); return; } /* Build an Ethernet header. */ memcpy(peth->dest, tabptr->at_ethaddr.ether_addr_octet, ETHER_ADDR_LEN); } /* Finish populating the Ethernet header */ memcpy(peth->src, dev->d_mac.ether_addr_octet, ETHER_ADDR_LEN); peth->type = HTONS(ETHTYPE_IP); dev->d_len += NET_LL_HDRLEN; } #endif /* CONFIG_NET_ARP */