Magellan Linux

  • Back to homepage
    • /[magellan-source]/trunk/mkinitrd-magellan/busybox/networking/udhcp/arpping.c

    Contents of /trunk/mkinitrd-magellan/busybox/networking/udhcp/arpping.c

    Parent Directory Parent Directory | Revision Log Revision Log

    Revision 816 - (show annotations) (download)
    Fri Apr 24 18:33:46 2009 UTC (15 years, 1 month ago) by niro
    File MIME type: text/plain
    File size: 3700 byte(s) 
    -updated to busybox-1.13.4
    1 /* vi: set sw=4 ts=4: */
    2 /*
    3 * arpping.c
    4 *
    5 * Mostly stolen from: dhcpcd - DHCP client daemon
    6 * by Yoichi Hariguchi <yoichi@fore.com>
    7 */
    8
    9 #include <netinet/if_ether.h>
    10 #include <net/if_arp.h>
    11
    12 #include "common.h"
    13 #include "dhcpd.h"
    14
    15
    16 struct arpMsg {
    17 /* Ethernet header */
    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 */
    21
    22 /* ARP packet */
    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) */
    33 } PACKED;
    34
    35 enum {
    36 ARP_MSG_SIZE = 0x2a
    37 };
    38
    39
    40 /* Returns 1 if no reply received */
    41
    42 int FAST_FUNC arpping(uint32_t test_ip, uint32_t from_ip, uint8_t *from_mac, const char *interface)
    43 {
    44 int timeout_ms;
    45 struct pollfd pfd[1];
    46 #define s (pfd[0].fd) /* socket */
    47 int rv = 1; /* "no reply received" yet */
    48 struct sockaddr addr; /* for interface name */
    49 struct arpMsg arp;
    50
    51 s = socket(PF_PACKET, SOCK_PACKET, htons(ETH_P_ARP));
    52 if (s == -1) {
    53 bb_perror_msg(bb_msg_can_not_create_raw_socket);
    54 return -1;
    55 }
    56
    57 if (setsockopt_broadcast(s) == -1) {
    58 bb_perror_msg("cannot enable bcast on raw socket");
    59 goto ret;
    60 }
    61
    62 /* send arp request */
    63 memset(&arp, 0, sizeof(arp));
    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 */
    74 /* tHaddr is zero-fiiled */ /* target hardware address */
    75 memcpy(arp.tInaddr, &test_ip, sizeof(test_ip)); /* target IP address */
    76
    77 memset(&addr, 0, sizeof(addr));
    78 safe_strncpy(addr.sa_data, interface, sizeof(addr.sa_data));
    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.
    82 goto ret;
    83 }
    84
    85 /* wait for arp reply, and check it */
    86 timeout_ms = 2000;
    87 do {
    88 int r;
    89 unsigned prevTime = monotonic_us();
    90
    91 pfd[0].events = POLLIN;
    92 r = safe_poll(pfd, 1, timeout_ms);
    93 if (r < 0)
    94 break;
    95 if (r) {
    96 r = read(s, &arp, sizeof(arp));
    97 if (r < 0)
    98 break;
    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 */
    103 && *((uint32_t *) arp.sInaddr) == test_ip
    104 ) {
    105 rv = 0;
    106 break;
    107 }
    108 }
    109 timeout_ms -= ((unsigned)monotonic_us() - prevTime) / 1000;
    110 } while (timeout_ms > 0);
    111
    112 ret:
    113 close(s);
    114 DEBUG("%srp reply received for this address", rv ? "No a" : "A");
    115 return rv;
    116 }