"Robert P. J. Day" | 63fc1a9 | 2006-07-02 19:47:05 +0000 | [diff] [blame] | 1 | /* vi: set sw=4 ts=4: */ |
Mike Frysinger | 7031f62 | 2006-05-08 03:20:50 +0000 | [diff] [blame] | 2 | /* |
| 3 | * arpping.c |
| 4 | * |
| 5 | * Mostly stolen from: dhcpcd - DHCP client daemon |
| 6 | * by Yoichi Hariguchi <yoichi@fore.com> |
| 7 | */ |
| 8 | |
Mike Frysinger | 7031f62 | 2006-05-08 03:20:50 +0000 | [diff] [blame] | 9 | #include <netinet/if_ether.h> |
| 10 | #include <net/if_arp.h> |
Mike Frysinger | 7031f62 | 2006-05-08 03:20:50 +0000 | [diff] [blame] | 11 | |
Mike Frysinger | 7031f62 | 2006-05-08 03:20:50 +0000 | [diff] [blame] | 12 | #include "common.h" |
Denis Vlasenko | 5a3395b | 2006-11-18 19:51:32 +0000 | [diff] [blame] | 13 | #include "dhcpd.h" |
| 14 | |
| 15 | |
| 16 | struct arpMsg { |
| 17 | /* Ethernet header */ |
Denis Vlasenko | 42b3dea | 2007-07-03 15:47:50 +0000 | [diff] [blame] | 18 | uint8_t h_dest[6]; /* 00 destination ether addr */ |
| 19 | uint8_t h_source[6]; /* 06 source ether addr */ |
| 20 | uint16_t h_proto; /* 0c packet type ID field */ |
Denis Vlasenko | 5a3395b | 2006-11-18 19:51:32 +0000 | [diff] [blame] | 21 | |
| 22 | /* ARP packet */ |
Denis Vlasenko | 42b3dea | 2007-07-03 15:47:50 +0000 | [diff] [blame] | 23 | uint16_t htype; /* 0e hardware type (must be ARPHRD_ETHER) */ |
| 24 | uint16_t ptype; /* 10 protocol type (must be ETH_P_IP) */ |
| 25 | uint8_t hlen; /* 12 hardware address length (must be 6) */ |
| 26 | uint8_t plen; /* 13 protocol address length (must be 4) */ |
| 27 | uint16_t operation; /* 14 ARP opcode */ |
| 28 | uint8_t sHaddr[6]; /* 16 sender's hardware address */ |
| 29 | uint8_t sInaddr[4]; /* 1c sender's IP address */ |
| 30 | uint8_t tHaddr[6]; /* 20 target's hardware address */ |
| 31 | uint8_t tInaddr[4]; /* 26 target's IP address */ |
| 32 | uint8_t pad[18]; /* 2a pad for min. ethernet payload (60 bytes) */ |
Denis Vlasenko | 5a3395b | 2006-11-18 19:51:32 +0000 | [diff] [blame] | 33 | } ATTRIBUTE_PACKED; |
Mike Frysinger | 7031f62 | 2006-05-08 03:20:50 +0000 | [diff] [blame] | 34 | |
Denis Vlasenko | 223bc97 | 2007-11-22 00:58:49 +0000 | [diff] [blame] | 35 | enum { |
| 36 | ARP_MSG_SIZE = 0x2a |
| 37 | }; |
| 38 | |
Mike Frysinger | 7031f62 | 2006-05-08 03:20:50 +0000 | [diff] [blame] | 39 | |
Denis Vlasenko | 42b3dea | 2007-07-03 15:47:50 +0000 | [diff] [blame] | 40 | /* Returns 1 if no reply received */ |
| 41 | |
| 42 | int arpping(uint32_t test_ip, uint32_t from_ip, uint8_t *from_mac, const char *interface) |
Mike Frysinger | 7031f62 | 2006-05-08 03:20:50 +0000 | [diff] [blame] | 43 | { |
Denis Vlasenko | 223bc97 | 2007-11-22 00:58:49 +0000 | [diff] [blame] | 44 | int timeout_ms; |
Denis Vlasenko | 87f3b26 | 2007-09-07 13:43:28 +0000 | [diff] [blame] | 45 | struct pollfd pfd[1]; |
| 46 | #define s (pfd[0].fd) /* socket */ |
Denis Vlasenko | 42b3dea | 2007-07-03 15:47:50 +0000 | [diff] [blame] | 47 | int rv = 1; /* "no reply received" yet */ |
| 48 | struct sockaddr addr; /* for interface name */ |
| 49 | struct arpMsg arp; |
Mike Frysinger | 7031f62 | 2006-05-08 03:20:50 +0000 | [diff] [blame] | 50 | |
Denis Vlasenko | 48237b0 | 2006-11-22 23:22:06 +0000 | [diff] [blame] | 51 | s = socket(PF_PACKET, SOCK_PACKET, htons(ETH_P_ARP)); |
| 52 | if (s == -1) { |
Denis Vlasenko | 3538b9a | 2006-09-06 18:36:50 +0000 | [diff] [blame] | 53 | bb_perror_msg(bb_msg_can_not_create_raw_socket); |
Mike Frysinger | 7031f62 | 2006-05-08 03:20:50 +0000 | [diff] [blame] | 54 | return -1; |
| 55 | } |
| 56 | |
Denis Vlasenko | 48237b0 | 2006-11-22 23:22:06 +0000 | [diff] [blame] | 57 | if (setsockopt_broadcast(s) == -1) { |
Denis Vlasenko | 223bc97 | 2007-11-22 00:58:49 +0000 | [diff] [blame] | 58 | bb_perror_msg("cannot enable bcast on raw socket"); |
Denis Vlasenko | 42b3dea | 2007-07-03 15:47:50 +0000 | [diff] [blame] | 59 | goto ret; |
Mike Frysinger | 7031f62 | 2006-05-08 03:20:50 +0000 | [diff] [blame] | 60 | } |
| 61 | |
| 62 | /* send arp request */ |
| 63 | memset(&arp, 0, sizeof(arp)); |
Denis Vlasenko | 42b3dea | 2007-07-03 15:47:50 +0000 | [diff] [blame] | 64 | memset(arp.h_dest, 0xff, 6); /* MAC DA */ |
| 65 | memcpy(arp.h_source, from_mac, 6); /* MAC SA */ |
| 66 | arp.h_proto = htons(ETH_P_ARP); /* protocol type (Ethernet) */ |
| 67 | arp.htype = htons(ARPHRD_ETHER); /* hardware type */ |
| 68 | arp.ptype = htons(ETH_P_IP); /* protocol type (ARP message) */ |
| 69 | arp.hlen = 6; /* hardware address length */ |
| 70 | arp.plen = 4; /* protocol address length */ |
| 71 | arp.operation = htons(ARPOP_REQUEST); /* ARP op code */ |
| 72 | memcpy(arp.sHaddr, from_mac, 6); /* source hardware address */ |
| 73 | memcpy(arp.sInaddr, &from_ip, sizeof(from_ip)); /* source IP address */ |
Denis Vlasenko | 223bc97 | 2007-11-22 00:58:49 +0000 | [diff] [blame] | 74 | /* tHaddr is zero-fiiled */ /* target hardware address */ |
Denis Vlasenko | 42b3dea | 2007-07-03 15:47:50 +0000 | [diff] [blame] | 75 | memcpy(arp.tInaddr, &test_ip, sizeof(test_ip)); /* target IP address */ |
Mike Frysinger | 7031f62 | 2006-05-08 03:20:50 +0000 | [diff] [blame] | 76 | |
| 77 | memset(&addr, 0, sizeof(addr)); |
Denis Vlasenko | 42b3dea | 2007-07-03 15:47:50 +0000 | [diff] [blame] | 78 | safe_strncpy(addr.sa_data, interface, sizeof(addr.sa_data)); |
Denis Vlasenko | 223bc97 | 2007-11-22 00:58:49 +0000 | [diff] [blame] | 79 | if (sendto(s, &arp, sizeof(arp), 0, &addr, sizeof(addr)) < 0) { |
| 80 | // TODO: error message? caller didn't expect us to fail, |
| 81 | // just returning 1 "no reply received" misleads it. |
Denis Vlasenko | 42b3dea | 2007-07-03 15:47:50 +0000 | [diff] [blame] | 82 | goto ret; |
Denis Vlasenko | 223bc97 | 2007-11-22 00:58:49 +0000 | [diff] [blame] | 83 | } |
Mike Frysinger | 7031f62 | 2006-05-08 03:20:50 +0000 | [diff] [blame] | 84 | |
Denis Vlasenko | 42b3dea | 2007-07-03 15:47:50 +0000 | [diff] [blame] | 85 | /* wait for arp reply, and check it */ |
Denis Vlasenko | 223bc97 | 2007-11-22 00:58:49 +0000 | [diff] [blame] | 86 | timeout_ms = 2000; |
Denis Vlasenko | 42b3dea | 2007-07-03 15:47:50 +0000 | [diff] [blame] | 87 | do { |
| 88 | int r; |
Denis Vlasenko | 87f3b26 | 2007-09-07 13:43:28 +0000 | [diff] [blame] | 89 | unsigned prevTime = monotonic_us(); |
| 90 | |
| 91 | pfd[0].events = POLLIN; |
Denis Vlasenko | 5d61e71 | 2007-09-27 10:09:59 +0000 | [diff] [blame] | 92 | r = safe_poll(pfd, 1, timeout_ms); |
Denis Vlasenko | 223bc97 | 2007-11-22 00:58:49 +0000 | [diff] [blame] | 93 | if (r < 0) |
Denis Vlasenko | 5d61e71 | 2007-09-27 10:09:59 +0000 | [diff] [blame] | 94 | break; |
Denis Vlasenko | 223bc97 | 2007-11-22 00:58:49 +0000 | [diff] [blame] | 95 | if (r) { |
| 96 | r = read(s, &arp, sizeof(arp)); |
| 97 | if (r < 0) |
Denis Vlasenko | 42b3dea | 2007-07-03 15:47:50 +0000 | [diff] [blame] | 98 | break; |
Denis Vlasenko | 223bc97 | 2007-11-22 00:58:49 +0000 | [diff] [blame] | 99 | if (r >= ARP_MSG_SIZE |
| 100 | && arp.operation == htons(ARPOP_REPLY) |
| 101 | /* don't check it: Linux doesn't return proper tHaddr (fixed in 2.6.24?) */ |
| 102 | /* && memcmp(arp.tHaddr, from_mac, 6) == 0 */ |
Denis Vlasenko | 42b3dea | 2007-07-03 15:47:50 +0000 | [diff] [blame] | 103 | && *((uint32_t *) arp.sInaddr) == test_ip |
| 104 | ) { |
Mike Frysinger | 7031f62 | 2006-05-08 03:20:50 +0000 | [diff] [blame] | 105 | rv = 0; |
| 106 | break; |
| 107 | } |
| 108 | } |
Denis Vlasenko | b89e202 | 2008-05-09 11:55:58 +0000 | [diff] [blame] | 109 | timeout_ms -= ((unsigned)monotonic_us() - prevTime) / 1000; |
Denis Vlasenko | 87f3b26 | 2007-09-07 13:43:28 +0000 | [diff] [blame] | 110 | } while (timeout_ms > 0); |
Denis Vlasenko | 42b3dea | 2007-07-03 15:47:50 +0000 | [diff] [blame] | 111 | |
| 112 | ret: |
Mike Frysinger | 7031f62 | 2006-05-08 03:20:50 +0000 | [diff] [blame] | 113 | close(s); |
Denis Vlasenko | 42b3dea | 2007-07-03 15:47:50 +0000 | [diff] [blame] | 114 | DEBUG("%srp reply received for this address", rv ? "No a" : "A"); |
Mike Frysinger | 7031f62 | 2006-05-08 03:20:50 +0000 | [diff] [blame] | 115 | return rv; |
| 116 | } |