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[/] [openrisc/] [trunk/] [rtos/] [freertos-6.1.1/] [Demo/] [Common/] [ethernet/] [lwIP/] [netif/] [etharp.c] - Rev 867
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/** * @file * Address Resolution Protocol module for IP over Ethernet * * Functionally, ARP is divided into two parts. The first maps an IP address * to a physical address when sending a packet, and the second part answers * requests from other machines for our physical address. * * This implementation complies with RFC 826 (Ethernet ARP). It supports * Gratuitious ARP from RFC3220 (IP Mobility Support for IPv4) section 4.6 * if an interface calls etharp_query(our_netif, its_ip_addr, NULL) upon * address change. */ /* * Copyright (c) 2001-2003 Swedish Institute of Computer Science. * Copyright (c) 2003-2004 Leon Woestenberg <leon.woestenberg@axon.tv> * Copyright (c) 2003-2004 Axon Digital Design B.V., The Netherlands. * 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. * * This file is part of the lwIP TCP/IP stack. * */ #include <string.h> #include "lwip/opt.h" #include "lwip/inet.h" #include "netif/etharp.h" #include "lwip/ip.h" #include "lwip/stats.h" #include "lwip/snmp.h" /* ARP needs to inform DHCP of any ARP replies? */ #if (LWIP_DHCP && DHCP_DOES_ARP_CHECK) # include "lwip/dhcp.h" #endif /** the time an ARP entry stays valid after its last update, * (240 * 5) seconds = 20 minutes. */ #define ARP_MAXAGE 240 /** the time an ARP entry stays pending after first request, * (2 * 5) seconds = 10 seconds. * * @internal Keep this number at least 2, otherwise it might * run out instantly if the timeout occurs directly after a request. */ #define ARP_MAXPENDING 2 #define HWTYPE_ETHERNET 1 /** ARP message types */ #define ARP_REQUEST 1 #define ARP_REPLY 2 #define ARPH_HWLEN(hdr) (ntohs((hdr)->_hwlen_protolen) >> 8) #define ARPH_PROTOLEN(hdr) (ntohs((hdr)->_hwlen_protolen) & 0xff) #define ARPH_HWLEN_SET(hdr, len) (hdr)->_hwlen_protolen = htons(ARPH_PROTOLEN(hdr) | ((len) << 8)) #define ARPH_PROTOLEN_SET(hdr, len) (hdr)->_hwlen_protolen = htons((len) | (ARPH_HWLEN(hdr) << 8)) enum etharp_state { ETHARP_STATE_EMPTY, ETHARP_STATE_PENDING, ETHARP_STATE_STABLE, /** @internal transitional state used in etharp_tmr() for convenience*/ ETHARP_STATE_EXPIRED }; struct etharp_entry { #if ARP_QUEUEING /** * Pointer to queue of pending outgoing packets on this ARP entry. */ struct pbuf *p; #endif struct ip_addr ipaddr; struct eth_addr ethaddr; enum etharp_state state; u8_t ctime; struct netif *netif; }; static const struct eth_addr ethbroadcast = {{0xff,0xff,0xff,0xff,0xff,0xff}}; static struct etharp_entry arp_table[ARP_TABLE_SIZE]; /** * Try hard to create a new entry - we want the IP address to appear in * the cache (even if this means removing an active entry or so). */ #define ETHARP_TRY_HARD 1 static s8_t find_entry(struct ip_addr *ipaddr, u8_t flags); static err_t update_arp_entry(struct netif *netif, struct ip_addr *ipaddr, struct eth_addr *ethaddr, u8_t flags); /** * Initializes ARP module. */ void etharp_init(void) { u8_t i; /* clear ARP entries */ for(i = 0; i < ARP_TABLE_SIZE; ++i) { arp_table[i].state = ETHARP_STATE_EMPTY; #if ARP_QUEUEING arp_table[i].p = NULL; #endif arp_table[i].ctime = 0; arp_table[i].netif = NULL; } } /** * Clears expired entries in the ARP table. * * This function should be called every ETHARP_TMR_INTERVAL microseconds (5 seconds), * in order to expire entries in the ARP table. */ void etharp_tmr(void) { u8_t i; LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_timer\n")); /* remove expired entries from the ARP table */ for (i = 0; i < ARP_TABLE_SIZE; ++i) { arp_table[i].ctime++; /* stable entry? */ if ((arp_table[i].state == ETHARP_STATE_STABLE) && /* entry has become old? */ (arp_table[i].ctime >= ARP_MAXAGE)) { LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_timer: expired stable entry %"U16_F".\n", (u16_t)i)); arp_table[i].state = ETHARP_STATE_EXPIRED; /* pending entry? */ } else if (arp_table[i].state == ETHARP_STATE_PENDING) { /* entry unresolved/pending for too long? */ if (arp_table[i].ctime >= ARP_MAXPENDING) { LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_timer: expired pending entry %"U16_F".\n", (u16_t)i)); arp_table[i].state = ETHARP_STATE_EXPIRED; #if ARP_QUEUEING } else if (arp_table[i].p != NULL) { /* resend an ARP query here */ #endif } } /* clean up entries that have just been expired */ if (arp_table[i].state == ETHARP_STATE_EXPIRED) { /* remove from SNMP ARP index tree */ snmp_delete_arpidx_tree(arp_table[i].netif, &arp_table[i].ipaddr); #if ARP_QUEUEING /* and empty packet queue */ if (arp_table[i].p != NULL) { /* remove all queued packets */ LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_timer: freeing entry %"U16_F", packet queue %p.\n", (u16_t)i, (void *)(arp_table[i].p))); pbuf_free(arp_table[i].p); arp_table[i].p = NULL; } #endif /* recycle entry for re-use */ arp_table[i].state = ETHARP_STATE_EMPTY; } } } /** * Search the ARP table for a matching or new entry. * * If an IP address is given, return a pending or stable ARP entry that matches * the address. If no match is found, create a new entry with this address set, * but in state ETHARP_EMPTY. The caller must check and possibly change the * state of the returned entry. * * If ipaddr is NULL, return a initialized new entry in state ETHARP_EMPTY. * * In all cases, attempt to create new entries from an empty entry. If no * empty entries are available and ETHARP_TRY_HARD flag is set, recycle * old entries. Heuristic choose the least important entry for recycling. * * @param ipaddr IP address to find in ARP cache, or to add if not found. * @param flags * - ETHARP_TRY_HARD: Try hard to create a entry by allowing recycling of * active (stable or pending) entries. * * @return The ARP entry index that matched or is created, ERR_MEM if no * entry is found or could be recycled. */ static s8_t find_entry(struct ip_addr *ipaddr, u8_t flags) { s8_t old_pending = ARP_TABLE_SIZE, old_stable = ARP_TABLE_SIZE; s8_t empty = ARP_TABLE_SIZE; u8_t i = 0, age_pending = 0, age_stable = 0; #if ARP_QUEUEING /* oldest entry with packets on queue */ s8_t old_queue = ARP_TABLE_SIZE; /* its age */ u8_t age_queue = 0; #endif /** * a) do a search through the cache, remember candidates * b) select candidate entry * c) create new entry */ /* a) in a single search sweep, do all of this * 1) remember the first empty entry (if any) * 2) remember the oldest stable entry (if any) * 3) remember the oldest pending entry without queued packets (if any) * 4) remember the oldest pending entry with queued packets (if any) * 5) search for a matching IP entry, either pending or stable * until 5 matches, or all entries are searched for. */ for (i = 0; i < ARP_TABLE_SIZE; ++i) { /* no empty entry found yet and now we do find one? */ if ((empty == ARP_TABLE_SIZE) && (arp_table[i].state == ETHARP_STATE_EMPTY)) { LWIP_DEBUGF(ETHARP_DEBUG, ("find_entry: found empty entry %"U16_F"\n", (u16_t)i)); /* remember first empty entry */ empty = i; } /* pending entry? */ else if (arp_table[i].state == ETHARP_STATE_PENDING) { /* if given, does IP address match IP address in ARP entry? */ if (ipaddr && ip_addr_cmp(ipaddr, &arp_table[i].ipaddr)) { LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("find_entry: found matching pending entry %"U16_F"\n", (u16_t)i)); /* found exact IP address match, simply bail out */ return i; #if ARP_QUEUEING /* pending with queued packets? */ } else if (arp_table[i].p != NULL) { if (arp_table[i].ctime >= age_queue) { old_queue = i; age_queue = arp_table[i].ctime; } #endif /* pending without queued packets? */ } else { if (arp_table[i].ctime >= age_pending) { old_pending = i; age_pending = arp_table[i].ctime; } } } /* stable entry? */ else if (arp_table[i].state == ETHARP_STATE_STABLE) { /* if given, does IP address match IP address in ARP entry? */ if (ipaddr && ip_addr_cmp(ipaddr, &arp_table[i].ipaddr)) { LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("find_entry: found matching stable entry %"U16_F"\n", (u16_t)i)); /* found exact IP address match, simply bail out */ return i; /* remember entry with oldest stable entry in oldest, its age in maxtime */ } else if (arp_table[i].ctime >= age_stable) { old_stable = i; age_stable = arp_table[i].ctime; } } } /* { we have no match } => try to create a new entry */ /* no empty entry found and not allowed to recycle? */ if ((empty == ARP_TABLE_SIZE) && ((flags & ETHARP_TRY_HARD) == 0)) { return (s8_t)ERR_MEM; } /* b) choose the least destructive entry to recycle: * 1) empty entry * 2) oldest stable entry * 3) oldest pending entry without queued packets * 4) oldest pending entry without queued packets * * { ETHARP_TRY_HARD is set at this point } */ /* 1) empty entry available? */ if (empty < ARP_TABLE_SIZE) { i = empty; LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("find_entry: selecting empty entry %"U16_F"\n", (u16_t)i)); } /* 2) found recyclable stable entry? */ else if (old_stable < ARP_TABLE_SIZE) { /* recycle oldest stable*/ i = old_stable; LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("find_entry: selecting oldest stable entry %"U16_F"\n", (u16_t)i)); #if ARP_QUEUEING /* no queued packets should exist on stable entries */ LWIP_ASSERT("arp_table[i].p == NULL", arp_table[i].p == NULL); #endif /* 3) found recyclable pending entry without queued packets? */ } else if (old_pending < ARP_TABLE_SIZE) { /* recycle oldest pending */ i = old_pending; LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("find_entry: selecting oldest pending entry %"U16_F" (without queue)\n", (u16_t)i)); #if ARP_QUEUEING /* 4) found recyclable pending entry with queued packets? */ } else if (old_queue < ARP_TABLE_SIZE) { /* recycle oldest pending */ i = old_queue; LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("find_entry: selecting oldest pending entry %"U16_F", freeing packet queue %p\n", (u16_t)i, (void *)(arp_table[i].p))); pbuf_free(arp_table[i].p); arp_table[i].p = NULL; #endif /* no empty or recyclable entries found */ } else { return (s8_t)ERR_MEM; } /* { empty or recyclable entry found } */ LWIP_ASSERT("i < ARP_TABLE_SIZE", i < ARP_TABLE_SIZE); if (arp_table[i].state != ETHARP_STATE_EMPTY) { snmp_delete_arpidx_tree(arp_table[i].netif, &arp_table[i].ipaddr); } /* recycle entry (no-op for an already empty entry) */ arp_table[i].state = ETHARP_STATE_EMPTY; /* IP address given? */ if (ipaddr != NULL) { /* set IP address */ ip_addr_set(&arp_table[i].ipaddr, ipaddr); } arp_table[i].ctime = 0; return (err_t)i; } /** * Update (or insert) a IP/MAC address pair in the ARP cache. * * If a pending entry is resolved, any queued packets will be sent * at this point. * * @param ipaddr IP address of the inserted ARP entry. * @param ethaddr Ethernet address of the inserted ARP entry. * @param flags Defines behaviour: * - ETHARP_TRY_HARD Allows ARP to insert this as a new item. If not specified, * only existing ARP entries will be updated. * * @return * - ERR_OK Succesfully updated ARP cache. * - ERR_MEM If we could not add a new ARP entry when ETHARP_TRY_HARD was set. * - ERR_ARG Non-unicast address given, those will not appear in ARP cache. * * @see pbuf_free() */ static err_t update_arp_entry(struct netif *netif, struct ip_addr *ipaddr, struct eth_addr *ethaddr, u8_t flags) { s8_t i; u8_t k; LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE | 3, ("update_arp_entry()\n")); LWIP_ASSERT("netif->hwaddr_len != 0", netif->hwaddr_len != 0); LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("update_arp_entry: %"U16_F".%"U16_F".%"U16_F".%"U16_F" - %02"X16_F":%02"X16_F":%02"X16_F":%02"X16_F":%02"X16_F":%02"X16_F"\n", ip4_addr1(ipaddr), ip4_addr2(ipaddr), ip4_addr3(ipaddr), ip4_addr4(ipaddr), ethaddr->addr[0], ethaddr->addr[1], ethaddr->addr[2], ethaddr->addr[3], ethaddr->addr[4], ethaddr->addr[5])); /* non-unicast address? */ if (ip_addr_isany(ipaddr) || ip_addr_isbroadcast(ipaddr, netif) || ip_addr_ismulticast(ipaddr)) { LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("update_arp_entry: will not add non-unicast IP address to ARP cache\n")); return ERR_ARG; } /* find or create ARP entry */ i = find_entry(ipaddr, flags); /* bail out if no entry could be found */ if (i < 0) return (err_t)i; /* mark it stable */ arp_table[i].state = ETHARP_STATE_STABLE; /* record network interface */ arp_table[i].netif = netif; /* insert in SNMP ARP index tree */ snmp_insert_arpidx_tree(netif, &arp_table[i].ipaddr); LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("update_arp_entry: updating stable entry %"S16_F"\n", (s16_t)i)); /* update address */ k = netif->hwaddr_len; while (k > 0) { k--; arp_table[i].ethaddr.addr[k] = ethaddr->addr[k]; } /* reset time stamp */ arp_table[i].ctime = 0; /* this is where we will send out queued packets! */ #if ARP_QUEUEING while (arp_table[i].p != NULL) { /* get the first packet on the queue */ struct pbuf *p = arp_table[i].p; /* Ethernet header */ struct eth_hdr *ethhdr = p->payload; /* remember (and reference) remainder of queue */ /* note: this will also terminate the p pbuf chain */ arp_table[i].p = pbuf_dequeue(p); /* fill-in Ethernet header */ k = netif->hwaddr_len; while(k > 0) { k--; ethhdr->dest.addr[k] = ethaddr->addr[k]; ethhdr->src.addr[k] = netif->hwaddr[k]; } ethhdr->type = htons(ETHTYPE_IP); LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("update_arp_entry: sending queued IP packet %p.\n", (void *)p)); /* send the queued IP packet */ netif->linkoutput(netif, p); /* free the queued IP packet */ pbuf_free(p); } #endif return ERR_OK; } /** * Finds (stable) ethernet/IP address pair from ARP table * using interface and IP address index. * @note the addresses in the ARP table are in network order! * * @param netif points to interface index * @param ipaddr points to the (network order) IP address index * @param eth_ret points to return pointer * @param ip_ret points to return pointer * @return table index if found, -1 otherwise */ s8_t etharp_find_addr(struct netif *netif, struct ip_addr *ipaddr, struct eth_addr **eth_ret, struct ip_addr **ip_ret) { s8_t i; i = 0; while (i < ARP_TABLE_SIZE) { if ((arp_table[i].state == ETHARP_STATE_STABLE) && (arp_table[i].netif == netif) && ip_addr_cmp(ipaddr, &arp_table[i].ipaddr) ) { *eth_ret = &arp_table[i].ethaddr; *ip_ret = &arp_table[i].ipaddr; return i; } i++; } return -1; } /** * Updates the ARP table using the given IP packet. * * Uses the incoming IP packet's source address to update the * ARP cache for the local network. The function does not alter * or free the packet. This function must be called before the * packet p is passed to the IP layer. * * @param netif The lwIP network interface on which the IP packet pbuf arrived. * @param pbuf The IP packet that arrived on netif. * * @return NULL * * @see pbuf_free() */ void etharp_ip_input(struct netif *netif, struct pbuf *p) { struct ethip_hdr *hdr; LWIP_ASSERT("netif != NULL", netif != NULL); /* Only insert an entry if the source IP address of the incoming IP packet comes from a host on the local network. */ hdr = p->payload; /* source is not on the local network? */ if (!ip_addr_netcmp(&(hdr->ip.src), &(netif->ip_addr), &(netif->netmask))) { /* do nothing */ return; } LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_ip_input: updating ETHARP table.\n")); /* update ARP table */ /* @todo We could use ETHARP_TRY_HARD if we think we are going to talk * back soon (for example, if the destination IP address is ours. */ update_arp_entry(netif, &(hdr->ip.src), &(hdr->eth.src), 0); } /** * Responds to ARP requests to us. Upon ARP replies to us, add entry to cache * send out queued IP packets. Updates cache with snooped address pairs. * * Should be called for incoming ARP packets. The pbuf in the argument * is freed by this function. * * @param netif The lwIP network interface on which the ARP packet pbuf arrived. * @param pbuf The ARP packet that arrived on netif. Is freed by this function. * @param ethaddr Ethernet address of netif. * * @return NULL * * @see pbuf_free() */ void etharp_arp_input(struct netif *netif, struct eth_addr *ethaddr, struct pbuf *p) { struct etharp_hdr *hdr; /* these are aligned properly, whereas the ARP header fields might not be */ struct ip_addr sipaddr, dipaddr; u8_t i; u8_t for_us; LWIP_ASSERT("netif != NULL", netif != NULL); /* drop short ARP packets */ if (p->tot_len < sizeof(struct etharp_hdr)) { LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE | 1, ("etharp_arp_input: packet dropped, too short (%"S16_F"/%"S16_F")\n", p->tot_len, (s16_t)sizeof(struct etharp_hdr))); pbuf_free(p); return; } hdr = p->payload; /* Copy struct ip_addr2 to aligned ip_addr, to support compilers without * structure packing (not using structure copy which breaks strict-aliasing rules). */ memcpy(&sipaddr, &hdr->sipaddr, sizeof(sipaddr)); memcpy(&dipaddr, &hdr->dipaddr, sizeof(dipaddr)); /* this interface is not configured? */ if (netif->ip_addr.addr == 0) { for_us = 0; } else { /* ARP packet directed to us? */ for_us = ip_addr_cmp(&dipaddr, &(netif->ip_addr)); } /* ARP message directed to us? */ if (for_us) { /* add IP address in ARP cache; assume requester wants to talk to us. * can result in directly sending the queued packets for this host. */ update_arp_entry(netif, &sipaddr, &(hdr->shwaddr), ETHARP_TRY_HARD); /* ARP message not directed to us? */ } else { /* update the source IP address in the cache, if present */ update_arp_entry(netif, &sipaddr, &(hdr->shwaddr), 0); } /* now act on the message itself */ switch (htons(hdr->opcode)) { /* ARP request? */ case ARP_REQUEST: /* ARP request. If it asked for our address, we send out a * reply. In any case, we time-stamp any existing ARP entry, * and possiby send out an IP packet that was queued on it. */ LWIP_DEBUGF (ETHARP_DEBUG | DBG_TRACE, ("etharp_arp_input: incoming ARP request\n")); /* ARP request for our address? */ if (for_us) { LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_arp_input: replying to ARP request for our IP address\n")); /* re-use pbuf to send ARP reply */ hdr->opcode = htons(ARP_REPLY); hdr->dipaddr = hdr->sipaddr; hdr->sipaddr = *(struct ip_addr2 *)&netif->ip_addr; i = netif->hwaddr_len; while(i > 0) { i--; hdr->dhwaddr.addr[i] = hdr->shwaddr.addr[i]; hdr->shwaddr.addr[i] = ethaddr->addr[i]; hdr->ethhdr.dest.addr[i] = hdr->dhwaddr.addr[i]; hdr->ethhdr.src.addr[i] = ethaddr->addr[i]; } hdr->hwtype = htons(HWTYPE_ETHERNET); ARPH_HWLEN_SET(hdr, netif->hwaddr_len); hdr->proto = htons(ETHTYPE_IP); ARPH_PROTOLEN_SET(hdr, sizeof(struct ip_addr)); hdr->ethhdr.type = htons(ETHTYPE_ARP); /* return ARP reply */ netif->linkoutput(netif, p); /* we are not configured? */ } else if (netif->ip_addr.addr == 0) { /* { for_us == 0 and netif->ip_addr.addr == 0 } */ LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_arp_input: we are unconfigured, ARP request ignored.\n")); /* request was not directed to us */ } else { /* { for_us == 0 and netif->ip_addr.addr != 0 } */ LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_arp_input: ARP request was not for us.\n")); } break; case ARP_REPLY: /* ARP reply. We already updated the ARP cache earlier. */ LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_arp_input: incoming ARP reply\n")); #if (LWIP_DHCP && DHCP_DOES_ARP_CHECK) /* DHCP wants to know about ARP replies from any host with an * IP address also offered to us by the DHCP server. We do not * want to take a duplicate IP address on a single network. * @todo How should we handle redundant (fail-over) interfaces? * */ dhcp_arp_reply(netif, &sipaddr); #endif break; default: LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_arp_input: ARP unknown opcode type %"S16_F"\n", htons(hdr->opcode))); break; } /* free ARP packet */ pbuf_free(p); } /** * Resolve and fill-in Ethernet address header for outgoing packet. * * For IP multicast and broadcast, corresponding Ethernet addresses * are selected and the packet is transmitted on the link. * * For unicast addresses, the packet is submitted to etharp_query(). In * case the IP address is outside the local network, the IP address of * the gateway is used. * * @param netif The lwIP network interface which the IP packet will be sent on. * @param ipaddr The IP address of the packet destination. * @param pbuf The pbuf(s) containing the IP packet to be sent. * * @return * - ERR_RTE No route to destination (no gateway to external networks), * or the return type of either etharp_query() or netif->linkoutput(). */ err_t etharp_output(struct netif *netif, struct ip_addr *ipaddr, struct pbuf *q) { struct eth_addr *dest, *srcaddr, mcastaddr; struct eth_hdr *ethhdr; u8_t i; /* make room for Ethernet header - should not fail */ if (pbuf_header(q, sizeof(struct eth_hdr)) != 0) { /* bail out */ LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE | 2, ("etharp_output: could not allocate room for header.\n")); LINK_STATS_INC(link.lenerr); return ERR_BUF; } /* assume unresolved Ethernet address */ dest = NULL; /* Determine on destination hardware address. Broadcasts and multicasts * are special, other IP addresses are looked up in the ARP table. */ /* broadcast destination IP address? */ if (ip_addr_isbroadcast(ipaddr, netif)) { /* broadcast on Ethernet also */ dest = (struct eth_addr *)ðbroadcast; /* multicast destination IP address? */ } else if (ip_addr_ismulticast(ipaddr)) { /* Hash IP multicast address to MAC address.*/ mcastaddr.addr[0] = 0x01; mcastaddr.addr[1] = 0x00; mcastaddr.addr[2] = 0x5e; mcastaddr.addr[3] = ip4_addr2(ipaddr) & 0x7f; mcastaddr.addr[4] = ip4_addr3(ipaddr); mcastaddr.addr[5] = ip4_addr4(ipaddr); /* destination Ethernet address is multicast */ dest = &mcastaddr; /* unicast destination IP address? */ } else { /* outside local network? */ if (!ip_addr_netcmp(ipaddr, &(netif->ip_addr), &(netif->netmask))) { /* interface has default gateway? */ if (netif->gw.addr != 0) { /* send to hardware address of default gateway IP address */ ipaddr = &(netif->gw); /* no default gateway available */ } else { /* no route to destination error (default gateway missing) */ return ERR_RTE; } } /* queue on destination Ethernet address belonging to ipaddr */ return etharp_query(netif, ipaddr, q); } /* continuation for multicast/broadcast destinations */ /* obtain source Ethernet address of the given interface */ srcaddr = (struct eth_addr *)netif->hwaddr; ethhdr = q->payload; i = netif->hwaddr_len; while(i > 0) { i--; ethhdr->dest.addr[i] = dest->addr[i]; ethhdr->src.addr[i] = srcaddr->addr[i]; } ethhdr->type = htons(ETHTYPE_IP); /* send packet directly on the link */ return netif->linkoutput(netif, q); } /** * Send an ARP request for the given IP address and/or queue a packet. * * If the IP address was not yet in the cache, a pending ARP cache entry * is added and an ARP request is sent for the given address. The packet * is queued on this entry. * * If the IP address was already pending in the cache, a new ARP request * is sent for the given address. The packet is queued on this entry. * * If the IP address was already stable in the cache, and a packet is * given, it is directly sent and no ARP request is sent out. * * If the IP address was already stable in the cache, and no packet is * given, an ARP request is sent out. * * @param netif The lwIP network interface on which ipaddr * must be queried for. * @param ipaddr The IP address to be resolved. * @param q If non-NULL, a pbuf that must be delivered to the IP address. * q is not freed by this function. * * @return * - ERR_BUF Could not make room for Ethernet header. * - ERR_MEM Hardware address unknown, and no more ARP entries available * to query for address or queue the packet. * - ERR_MEM Could not queue packet due to memory shortage. * - ERR_RTE No route to destination (no gateway to external networks). * - ERR_ARG Non-unicast address given, those will not appear in ARP cache. * */ err_t etharp_query(struct netif *netif, struct ip_addr *ipaddr, struct pbuf *q) { struct eth_addr * srcaddr = (struct eth_addr *)netif->hwaddr; err_t result = ERR_MEM; s8_t i; /* ARP entry index */ u8_t k; /* Ethernet address octet index */ /* non-unicast address? */ if (ip_addr_isbroadcast(ipaddr, netif) || ip_addr_ismulticast(ipaddr) || ip_addr_isany(ipaddr)) { LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_query: will not add non-unicast IP address to ARP cache\n")); return ERR_ARG; } /* find entry in ARP cache, ask to create entry if queueing packet */ i = find_entry(ipaddr, ETHARP_TRY_HARD); /* could not find or create entry? */ if (i < 0) { LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_query: could not create ARP entry\n")); if (q) LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_query: packet dropped\n")); return (err_t)i; } /* mark a fresh entry as pending (we just sent a request) */ if (arp_table[i].state == ETHARP_STATE_EMPTY) { arp_table[i].state = ETHARP_STATE_PENDING; } /* { i is either a STABLE or (new or existing) PENDING entry } */ LWIP_ASSERT("arp_table[i].state == PENDING or STABLE", ((arp_table[i].state == ETHARP_STATE_PENDING) || (arp_table[i].state == ETHARP_STATE_STABLE))); /* do we have a pending entry? or an implicit query request? */ if ((arp_table[i].state == ETHARP_STATE_PENDING) || (q == NULL)) { /* try to resolve it; send out ARP request */ result = etharp_request(netif, ipaddr); } /* packet given? */ if (q != NULL) { /* stable entry? */ if (arp_table[i].state == ETHARP_STATE_STABLE) { /* we have a valid IP->Ethernet address mapping, * fill in the Ethernet header for the outgoing packet */ struct eth_hdr *ethhdr = q->payload; k = netif->hwaddr_len; while(k > 0) { k--; ethhdr->dest.addr[k] = arp_table[i].ethaddr.addr[k]; ethhdr->src.addr[k] = srcaddr->addr[k]; } ethhdr->type = htons(ETHTYPE_IP); LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_query: sending packet %p\n", (void *)q)); /* send the packet */ result = netif->linkoutput(netif, q); /* pending entry? (either just created or already pending */ } else if (arp_table[i].state == ETHARP_STATE_PENDING) { #if ARP_QUEUEING /* queue the given q packet */ struct pbuf *p; /* copy any PBUF_REF referenced payloads into PBUF_RAM */ /* (the caller of lwIP assumes the referenced payload can be * freed after it returns from the lwIP call that brought us here) */ p = pbuf_take(q); /* packet could be taken over? */ if (p != NULL) { /* queue packet ... */ if (arp_table[i].p == NULL) { /* ... in the empty queue */ pbuf_ref(p); arp_table[i].p = p; #if 0 /* multi-packet-queueing disabled, see bug #11400 */ } else { /* ... at tail of non-empty queue */ pbuf_queue(arp_table[i].p, p); #endif } LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_query: queued packet %p on ARP entry %"S16_F"\n", (void *)q, (s16_t)i)); result = ERR_OK; } else { LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_query: could not queue a copy of PBUF_REF packet %p (out of memory)\n", (void *)q)); /* { result == ERR_MEM } through initialization */ } #else /* ARP_QUEUEING == 0 */ /* q && state == PENDING && ARP_QUEUEING == 0 => result = ERR_MEM */ /* { result == ERR_MEM } through initialization */ LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_query: Ethernet destination address unknown, queueing disabled, packet %p dropped\n", (void *)q)); #endif } } return result; } err_t etharp_request(struct netif *netif, struct ip_addr *ipaddr) { struct pbuf *p; struct eth_addr * srcaddr = (struct eth_addr *)netif->hwaddr; err_t result = ERR_OK; u8_t k; /* ARP entry index */ /* allocate a pbuf for the outgoing ARP request packet */ p = pbuf_alloc(PBUF_LINK, sizeof(struct etharp_hdr), PBUF_RAM); /* could allocate a pbuf for an ARP request? */ if (p != NULL) { struct etharp_hdr *hdr = p->payload; LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_request: sending ARP request.\n")); hdr->opcode = htons(ARP_REQUEST); k = netif->hwaddr_len; while(k > 0) { k--; hdr->shwaddr.addr[k] = srcaddr->addr[k]; /* the hardware address is what we ask for, in * a request it is a don't-care value, we use zeroes */ hdr->dhwaddr.addr[k] = 0x00; } hdr->dipaddr = *(struct ip_addr2 *)ipaddr; hdr->sipaddr = *(struct ip_addr2 *)&netif->ip_addr; hdr->hwtype = htons(HWTYPE_ETHERNET); ARPH_HWLEN_SET(hdr, netif->hwaddr_len); hdr->proto = htons(ETHTYPE_IP); ARPH_PROTOLEN_SET(hdr, sizeof(struct ip_addr)); k = netif->hwaddr_len; while(k > 0) { k--; /* broadcast to all network interfaces on the local network */ hdr->ethhdr.dest.addr[k] = 0xff; hdr->ethhdr.src.addr[k] = srcaddr->addr[k]; } hdr->ethhdr.type = htons(ETHTYPE_ARP); /* send ARP query */ result = netif->linkoutput(netif, p); /* free ARP query packet */ pbuf_free(p); p = NULL; /* could not allocate pbuf for ARP request */ } else { result = ERR_MEM; LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE | 2, ("etharp_request: could not allocate pbuf for ARP request.\n")); } return result; }
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