hush/networking/udhcp/arpping.c
Denis Vlasenko 5d61e71c3a introduce safe_poll (fixes a problem in top)
function                                             old     new   delta
safe_poll                                              -      77     +77
svlogd_main                                         1470    1466      -4
zcip_main                                           1530    1524      -6
forkexec                                            1345    1338      -7
decode_format_string                                 795     788      -7
collect_blk                                          474     467      -7
buffer_pread                                         540     532      -8
tftp                                                1182    1172     -10
microcom_main                                        763     749     -14
arpping                                              441     424     -17
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 0/9 up/down: 77/-80)             Total: -3 bytes
   text    data     bss     dec     hex filename
 770162    1034   10404  781600   bed20 busybox_old
 770158    1034   10404  781596   bed1c busybox_unstripped
2007-09-27 10:09:59 +00:00

106 lines
3.3 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_ms = 2000;
struct pollfd pfd[1];
#define s (pfd[0].fd) /* socket */
int rv = 1; /* "no reply received" yet */
struct sockaddr addr; /* for interface name */
struct arpMsg arp;
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;
unsigned prevTime = monotonic_us();
pfd[0].events = POLLIN;
r = safe_poll(pfd, 1, timeout_ms);
if (r < 0) {
break;
} else if (r) {
if (read(s, &arp, sizeof(arp)) < 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_ms -= (monotonic_us() - prevTime) / 1000;
} while (timeout_ms > 0);
ret:
close(s);
DEBUG("%srp reply received for this address", rv ? "No a" : "A");
return rv;
}