/**************************************************************************** * net/arp/arp_table.c * Implementation of the ARP Address Resolution Protocol. * * Copyright (C) 2007-2009, 2011, 2014, 2018 Gregory Nutt. All rights * reserved. * Author: Gregory Nutt * * Based originally 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 #ifdef CONFIG_NET #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef CONFIG_NET_ARP /**************************************************************************** * Private Types ****************************************************************************/ struct arp_table_info_s { in_addr_t ai_ipaddr; /* IP address for lookup */ FAR struct ether_addr *ai_ethaddr; /* Location to return the MAC address */ }; /**************************************************************************** * Private Data ****************************************************************************/ /* The table of known address mappings */ static struct arp_entry_s g_arptable[CONFIG_NET_ARPTAB_SIZE]; static uint8_t g_arptime; /**************************************************************************** * Private Functions ****************************************************************************/ /**************************************************************************** * Name: arp_match * * Description: * This is a callback that checks if the Ethernet network device has the * indicated IPv4 address assigned to it. * ****************************************************************************/ static int arp_match(FAR struct net_driver_s *dev, FAR void *arg) { FAR struct arp_table_info_s *info = arg; /* Make sure that this is an Ethernet device (or an IEEE 802.11 device * which is also Ethernet) */ if (dev->d_lltype != NET_LL_ETHERNET && dev->d_lltype != NET_LL_IEEE80211) { return 0; } /* Check if the network device has been assigned the IP address of the * lookup. */ if (!net_ipv4addr_cmp(dev->d_ipaddr, info->ai_ipaddr)) { return 0; } /* Yes.. Return the matching Ethernet MAC address if the caller of * arp_find() provided a non-NULL location. */ if (info->ai_ethaddr != NULL) { memcpy(info->ai_ethaddr, &dev->d_mac.ether, ETHER_ADDR_LEN); } /* Return success in any event */ return 1; } /**************************************************************************** * Public Functions ****************************************************************************/ /**************************************************************************** * Name: arp_reset * * Description: * Re-initialize the ARP table. * ****************************************************************************/ void arp_reset(void) { int i; for (i = 0; i < CONFIG_NET_ARPTAB_SIZE; ++i) { memset(&g_arptable[i].at_ipaddr, 0, sizeof(in_addr_t)); } } /**************************************************************************** * Name: arp_timer * * Description: * This function performs periodic timer processing in the ARP module * and should be called at regular intervals. The recommended interval * is 10 seconds between the calls. It is responsible for flushing old * entries in the ARP table. * ****************************************************************************/ void arp_timer(void) { FAR struct arp_entry_s *tabptr; int i; ++g_arptime; for (i = 0; i < CONFIG_NET_ARPTAB_SIZE; ++i) { tabptr = &g_arptable[i]; if (tabptr->at_ipaddr != 0 && g_arptime - tabptr->at_time >= CONFIG_NET_ARP_MAXAGE) { tabptr->at_ipaddr = 0; } } } /**************************************************************************** * Name: arp_update * * Description: * Add the IP/HW address mapping to the ARP table -OR- change the IP * address of an existing association. * * Input Parameters: * ipaddr - The IP address as an inaddr_t * ethaddr - Refers to a HW address uint8_t[IFHWADDRLEN] * * Returned Value: * Zero (OK) if the ARP table entry was successfully modified. A negated * errno value is returned on any error. * * Assumptions * The network is locked to assure exclusive access to the ARP table * ****************************************************************************/ int arp_update(in_addr_t ipaddr, FAR uint8_t *ethaddr) { struct arp_entry_s *tabptr = NULL; int i; /* Walk through the ARP mapping table and try to find an entry to * update. If none is found, the IP -> MAC address mapping is * inserted in the ARP table. */ for (i = 0; i < CONFIG_NET_ARPTAB_SIZE; ++i) { tabptr = &g_arptable[i]; /* Only check those entries that are actually in use. */ if (tabptr->at_ipaddr != 0) { /* Check if the source IP address of the incoming packet matches * the IP address in this ARP table entry. */ if (net_ipv4addr_cmp(ipaddr, tabptr->at_ipaddr)) { /* An old entry found, update this and return. */ memcpy(tabptr->at_ethaddr.ether_addr_octet, ethaddr, ETHER_ADDR_LEN); tabptr->at_time = g_arptime; return OK; } } } /* If we get here, no existing ARP table entry was found, so we create one. */ /* First, we try to find an unused entry in the ARP table. */ for (i = 0; i < CONFIG_NET_ARPTAB_SIZE; ++i) { tabptr = &g_arptable[i]; if (tabptr->at_ipaddr == 0) { break; } } /* If no unused entry is found, we try to find the oldest entry and * throw it away. */ if (i == CONFIG_NET_ARPTAB_SIZE) { uint8_t tmpage = 0; int j = 0; for (i = 0; i < CONFIG_NET_ARPTAB_SIZE; ++i) { tabptr = &g_arptable[i]; if (g_arptime - tabptr->at_time > tmpage) { tmpage = g_arptime - tabptr->at_time; j = i; } } i = j; tabptr = &g_arptable[i]; } /* Now, i is the ARP table entry which we will fill with the new * information. */ tabptr->at_ipaddr = ipaddr; memcpy(tabptr->at_ethaddr.ether_addr_octet, ethaddr, ETHER_ADDR_LEN); tabptr->at_time = g_arptime; return OK; } /**************************************************************************** * Name: arp_hdr_update * * Description: * Add the IP/HW address mapping to the ARP table -OR- change the IP * address of an existing association. * * Input Parameters: * pipaddr - Refers to an IP address uint16_t[2] in network order * ethaddr - Refers to a HW address uint8_t[IFHWADDRLEN] * * Returned Value: * Zero (OK) if the ARP table entry was successfully modified. A negated * errno value is returned on any error. * * Assumptions * The network is locked to assure exclusive access to the ARP table * ****************************************************************************/ void arp_hdr_update(FAR uint16_t *pipaddr, FAR uint8_t *ethaddr) { in_addr_t ipaddr = net_ip4addr_conv32(pipaddr); /* Update the ARP table */ (void)arp_update(ipaddr, ethaddr); } /**************************************************************************** * Name: arp_lookup * * Description: * Find the ARP entry corresponding to this IP address in the ARP table. * * Input Parameters: * ipaddr - Refers to an IP address in network order * * Assumptions: * The network is locked to assure exclusive access to the ARP table. * The return value will become unstable when the network is unlocked. * ****************************************************************************/ FAR struct arp_entry_s *arp_lookup(in_addr_t ipaddr) { FAR struct arp_entry_s *tabptr; int i; /* Check if the IPv4 address is already in the ARP table. */ for (i = 0; i < CONFIG_NET_ARPTAB_SIZE; ++i) { tabptr = &g_arptable[i]; if (net_ipv4addr_cmp(ipaddr, tabptr->at_ipaddr)) { return tabptr; } } /* Not found */ return NULL; } /**************************************************************************** * Name: arp_find * * Description: * Find the ARP entry corresponding to this IP address which may or may * not be in the ARP table (it may, instead, be a local network device). * * Input Parameters: * ipaddr - Refers to an IP address in network order * ethaddr - Location to return the corresponding Ethernet MAN address. * This address may be NULL. In that case, this function may be * used simply to determine if the Ethernet MAC address is * available. * * Assumptions * The network is locked to assure exclusive access to the ARP table. * ****************************************************************************/ int arp_find(in_addr_t ipaddr, FAR struct ether_addr *ethaddr) { FAR struct arp_entry_s *tabptr; struct arp_table_info_s info; /* Check if the IPv4 address is already in the ARP table. */ tabptr = arp_lookup(ipaddr); if (tabptr != NULL) { /* Yes.. return the Ethernet MAC address if the caller has provided a * non-NULL address in 'ethaddr'. */ if (ethaddr != NULL) { memcpy(ethaddr, &tabptr->at_ethaddr, ETHER_ADDR_LEN); } /* Return success in any case meaning that a valid Ethernet MAC * address mapping is available for the IP address. */ return OK; } /* No.. check if the IPv4 address is the address assigned to a local * Ethernet network device. If so, return a mapping of that IP address * to the Ethernet MAC address assigned to the network device. */ info.ai_ipaddr = ipaddr; info.ai_ethaddr = ethaddr; if (netdev_foreach(arp_match, &info) != 0) { return OK; } /* Not found */ return -ENOENT; } /**************************************************************************** * Name: arp_delete * * Description: * Remove an IP association from the ARP table * * Input Parameters: * ipaddr - Refers to an IP address in network order * * Assumptions * The network is locked to assure exclusive access to the ARP table. * ****************************************************************************/ void arp_delete(in_addr_t ipaddr) { FAR struct arp_entry_s *tabptr; /* Check if the IPv4 address is in the ARP table. */ tabptr = arp_lookup(ipaddr); if (tabptr != NULL) { /* Yes.. Set the IP address to zero to "delete" it */ tabptr->at_ipaddr = 0; } } #endif /* CONFIG_NET_ARP */ #endif /* CONFIG_NET */