hush/networking/udhcp/arpping.c
Denis Vlasenko 42b3dea9bf udhcp: many small fixes:
* arpping(): smaller and even probably fixed
* lots of variables/params converted: ulong -> uint32_t
* uptime() nuked in favor of monotonic_sec()
* udhcp_get_packet(): only one "bad vendor", simplify

function                                             old     new   delta
reservedIp                                            36      35      -1
udhcpc_main                                         2462    2460      -2
addStaticLease                                        64      62      -2
static.broken_vendors                                 16       -     -16
uptime                                                19       -     -19
udhcpd_main                                         1273    1238     -35
udhcp_get_packet                                     223     184     -39
.rodata                                           144162  144106     -56
arpping                                              690     609     -81
------------------------------------------------------------------------------
(add/remove: 0/2 grow/shrink: 0/7 up/down: 0/-251)           Total: -251 bytes
   text    data     bss     dec     hex filename
 734241    3028   14400  751669   b7835 busybox_old
 734005    3028   14400  751433   b7749 busybox_unstripped
2007-07-03 15:47:50 +00:00

112 lines
3.5 KiB
C

/* vi: set sw=4 ts=4: */
/*
* arpping.c
*
* Mostly stolen from: dhcpcd - DHCP client daemon
* by Yoichi Hariguchi <yoichi@fore.com>
*/
#include <netinet/if_ether.h>
#include <net/if_arp.h>
#include "common.h"
#include "dhcpd.h"
struct arpMsg {
/* Ethernet header */
uint8_t h_dest[6]; /* 00 destination ether addr */
uint8_t h_source[6]; /* 06 source ether addr */
uint16_t h_proto; /* 0c packet type ID field */
/* ARP packet */
uint16_t htype; /* 0e hardware type (must be ARPHRD_ETHER) */
uint16_t ptype; /* 10 protocol type (must be ETH_P_IP) */
uint8_t hlen; /* 12 hardware address length (must be 6) */
uint8_t plen; /* 13 protocol address length (must be 4) */
uint16_t operation; /* 14 ARP opcode */
uint8_t sHaddr[6]; /* 16 sender's hardware address */
uint8_t sInaddr[4]; /* 1c sender's IP address */
uint8_t tHaddr[6]; /* 20 target's hardware address */
uint8_t tInaddr[4]; /* 26 target's IP address */
uint8_t pad[18]; /* 2a pad for min. ethernet payload (60 bytes) */
} ATTRIBUTE_PACKED;
/* Returns 1 if no reply received */
int arpping(uint32_t test_ip, uint32_t from_ip, uint8_t *from_mac, const char *interface)
{
int timeout = 2;
int s; /* socket */
int rv = 1; /* "no reply received" yet */
struct sockaddr addr; /* for interface name */
struct arpMsg arp;
fd_set fdset;
struct timeval tm;
unsigned prevTime;
s = socket(PF_PACKET, SOCK_PACKET, htons(ETH_P_ARP));
if (s == -1) {
bb_perror_msg(bb_msg_can_not_create_raw_socket);
return -1;
}
if (setsockopt_broadcast(s) == -1) {
bb_perror_msg("cannot setsocketopt on raw socket");
goto ret;
}
/* send arp request */
memset(&arp, 0, sizeof(arp));
memset(arp.h_dest, 0xff, 6); /* MAC DA */
memcpy(arp.h_source, from_mac, 6); /* MAC SA */
arp.h_proto = htons(ETH_P_ARP); /* protocol type (Ethernet) */
arp.htype = htons(ARPHRD_ETHER); /* hardware type */
arp.ptype = htons(ETH_P_IP); /* protocol type (ARP message) */
arp.hlen = 6; /* hardware address length */
arp.plen = 4; /* protocol address length */
arp.operation = htons(ARPOP_REQUEST); /* ARP op code */
memcpy(arp.sHaddr, from_mac, 6); /* source hardware address */
memcpy(arp.sInaddr, &from_ip, sizeof(from_ip)); /* source IP address */
/* tHaddr */ /* target hardware address */
memcpy(arp.tInaddr, &test_ip, sizeof(test_ip)); /* target IP address */
memset(&addr, 0, sizeof(addr));
safe_strncpy(addr.sa_data, interface, sizeof(addr.sa_data));
if (sendto(s, &arp, sizeof(arp), 0, &addr, sizeof(addr)) < 0)
goto ret;
/* wait for arp reply, and check it */
do {
int r;
prevTime = monotonic_sec();
FD_ZERO(&fdset);
FD_SET(s, &fdset);
tm.tv_sec = timeout;
tm.tv_usec = 0;
r = select(s + 1, &fdset, NULL, NULL, &tm);
if (r < 0) {
bb_perror_msg("error on ARPING request");
if (errno != EINTR)
break;
} else if (r) {
if (recv(s, &arp, sizeof(arp), 0) < 0)
break;
if (arp.operation == htons(ARPOP_REPLY)
&& memcmp(arp.tHaddr, from_mac, 6) == 0
&& *((uint32_t *) arp.sInaddr) == test_ip
) {
rv = 0;
break;
}
}
timeout -= monotonic_sec() - prevTime;
} while (timeout > 0);
ret:
close(s);
DEBUG("%srp reply received for this address", rv ? "No a" : "A");
return rv;
}