/**************************************************************************** * net/arp/arp_table.c * Implementation of the ARP Address Resolution Protocol. * * Copyright (C) 2007-2009, 2011, 2014 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 #ifdef CONFIG_NET_ARP /**************************************************************************** * Pre-processor Definitions ****************************************************************************/ /**************************************************************************** * Private Types ****************************************************************************/ /**************************************************************************** * Private Data ****************************************************************************/ /* The table of known address mappings */ static struct arp_entry g_arptable[CONFIG_NET_ARPTAB_SIZE]; static uint8_t g_arptime; /**************************************************************************** * Private Functions ****************************************************************************/ /**************************************************************************** * Public Functions ****************************************************************************/ /**************************************************************************** * Name: arp_init * * Description: * Initialize the ARP module. This function must be called before any of * the other ARP functions. * ****************************************************************************/ void arp_init(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) { struct arp_entry *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 >= UIP_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: * pipaddr - Refers to an IP address uint16_t[2] * ethaddr - Refers to a HW address uint8_t[IFHWADDRLEN] * * Assumptions * Interrupts are disabled * ****************************************************************************/ void arp_update(uint16_t *pipaddr, uint8_t *ethaddr) { struct arp_entry *tabptr = NULL; in_addr_t ipaddr = uip_ip4addr_conv(pipaddr); 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 (uip_ipaddr_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; } } } /* 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; } /**************************************************************************** * Name: arp_find * * Description: * Find the ARP entry corresponding to this IP address. * * Input parameters: * ipaddr - Refers to an IP address in network order * * Assumptions * Interrupts are disabled; Returned value will become unstable when * interrupts are re-enabled or if any other uIP APIs are called. * ****************************************************************************/ struct arp_entry *arp_find(in_addr_t ipaddr) { struct arp_entry *tabptr; int i; for (i = 0; i < CONFIG_NET_ARPTAB_SIZE; ++i) { tabptr = &g_arptable[i]; if (uip_ipaddr_cmp(ipaddr, tabptr->at_ipaddr)) { return tabptr; } } return NULL; } #endif /* CONFIG_NET_ARP */ #endif /* CONFIG_NET */