| Mike Frysinger | 7031f62 | 2006-05-08 03:20:50 +0000 | [diff] [blame] | 1 | /* |
| 2 | * arpping.c |
| 3 | * |
| 4 | * Mostly stolen from: dhcpcd - DHCP client daemon |
| 5 | * by Yoichi Hariguchi <yoichi@fore.com> |
| 6 | */ |
| 7 | |
| Mike Frysinger | 7031f62 | 2006-05-08 03:20:50 +0000 | [diff] [blame] | 8 | #include <time.h> |
| 9 | #include <sys/socket.h> |
| 10 | #include <netinet/if_ether.h> |
| 11 | #include <net/if_arp.h> |
| 12 | #include <netinet/in.h> |
| 13 | #include <string.h> |
| 14 | #include <unistd.h> |
| 15 | #include <errno.h> |
| 16 | |
| 17 | #include "dhcpd.h" |
| 18 | #include "arpping.h" |
| 19 | #include "common.h" |
| 20 | |
| 21 | /* args: yiaddr - what IP to ping |
| 22 | * ip - our ip |
| 23 | * mac - our arp address |
| 24 | * interface - interface to use |
| 25 | * retn: 1 addr free |
| 26 | * 0 addr used |
| 27 | * -1 error |
| 28 | */ |
| 29 | |
| 30 | /* FIXME: match response against chaddr */ |
| 31 | int arpping(uint32_t yiaddr, uint32_t ip, uint8_t *mac, char *interface) |
| 32 | { |
| 33 | |
| 34 | int timeout = 2; |
| 35 | int optval = 1; |
| 36 | int s; /* socket */ |
| 37 | int rv = 1; /* return value */ |
| 38 | struct sockaddr addr; /* for interface name */ |
| 39 | struct arpMsg arp; |
| 40 | fd_set fdset; |
| 41 | struct timeval tm; |
| 42 | time_t prevTime; |
| 43 | |
| 44 | |
| 45 | if ((s = socket (PF_PACKET, SOCK_PACKET, htons(ETH_P_ARP))) == -1) { |
| 46 | #ifdef IN_BUSYBOX |
| 47 | LOG(LOG_ERR, bb_msg_can_not_create_raw_socket); |
| 48 | #else |
| 49 | LOG(LOG_ERR, "Could not open raw socket"); |
| 50 | #endif |
| 51 | return -1; |
| 52 | } |
| 53 | |
| 54 | if (setsockopt(s, SOL_SOCKET, SO_BROADCAST, &optval, sizeof(optval)) == -1) { |
| 55 | LOG(LOG_ERR, "Could not setsocketopt on raw socket"); |
| 56 | close(s); |
| 57 | return -1; |
| 58 | } |
| 59 | |
| 60 | /* send arp request */ |
| 61 | memset(&arp, 0, sizeof(arp)); |
| 62 | memcpy(arp.h_dest, MAC_BCAST_ADDR, 6); /* MAC DA */ |
| 63 | memcpy(arp.h_source, mac, 6); /* MAC SA */ |
| 64 | arp.h_proto = htons(ETH_P_ARP); /* protocol type (Ethernet) */ |
| 65 | arp.htype = htons(ARPHRD_ETHER); /* hardware type */ |
| 66 | arp.ptype = htons(ETH_P_IP); /* protocol type (ARP message) */ |
| 67 | arp.hlen = 6; /* hardware address length */ |
| 68 | arp.plen = 4; /* protocol address length */ |
| 69 | arp.operation = htons(ARPOP_REQUEST); /* ARP op code */ |
| 70 | memcpy(arp.sInaddr, &ip, sizeof(ip)); /* source IP address */ |
| 71 | memcpy(arp.sHaddr, mac, 6); /* source hardware address */ |
| 72 | memcpy(arp.tInaddr, &yiaddr, sizeof(yiaddr)); /* target IP address */ |
| 73 | |
| 74 | memset(&addr, 0, sizeof(addr)); |
| 75 | strcpy(addr.sa_data, interface); |
| 76 | if (sendto(s, &arp, sizeof(arp), 0, &addr, sizeof(addr)) < 0) |
| 77 | rv = 0; |
| 78 | |
| 79 | /* wait arp reply, and check it */ |
| 80 | tm.tv_usec = 0; |
| 81 | prevTime = uptime(); |
| 82 | while (timeout > 0) { |
| 83 | FD_ZERO(&fdset); |
| 84 | FD_SET(s, &fdset); |
| 85 | tm.tv_sec = timeout; |
| 86 | if (select(s + 1, &fdset, (fd_set *) NULL, (fd_set *) NULL, &tm) < 0) { |
| 87 | DEBUG(LOG_ERR, "Error on ARPING request: %m"); |
| 88 | if (errno != EINTR) rv = 0; |
| 89 | } else if (FD_ISSET(s, &fdset)) { |
| 90 | if (recv(s, &arp, sizeof(arp), 0) < 0 ) rv = 0; |
| 91 | if (arp.operation == htons(ARPOP_REPLY) && |
| 92 | memcmp(arp.tHaddr, mac, 6) == 0 && |
| 93 | *((uint32_t *) arp.sInaddr) == yiaddr) { |
| 94 | DEBUG(LOG_INFO, "Valid arp reply receved for this address"); |
| 95 | rv = 0; |
| 96 | break; |
| 97 | } |
| 98 | } |
| 99 | timeout -= uptime() - prevTime; |
| 100 | prevTime = uptime(); |
| 101 | } |
| 102 | close(s); |
| 103 | DEBUG(LOG_INFO, "%salid arp replies for this address", rv ? "No v" : "V"); |
| 104 | return rv; |
| 105 | } |