hush/networking/udhcp/arpping.c

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/*
* arpping.c
*
* Mostly stolen from: dhcpcd - DHCP client daemon
* by Yoichi Hariguchi <yoichi@fore.com>
*/
#include <sys/time.h>
#include <time.h>
#include <sys/socket.h>
#include <netinet/if_ether.h>
#include <net/if_arp.h>
#include <netinet/in.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include "dhcpd.h"
#include "arpping.h"
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#include "common.h"
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/* args: yiaddr - what IP to ping
* ip - our ip
* mac - our arp address
* interface - interface to use
* retn: 1 addr free
* 0 addr used
* -1 error
*/
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/* FIXME: match response against chaddr */
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int arpping(uint32_t yiaddr, uint32_t ip, uint8_t *mac, char *interface)
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{
int timeout = 2;
int optval = 1;
int s; /* socket */
int rv = 1; /* return value */
struct sockaddr addr; /* for interface name */
struct arpMsg arp;
fd_set fdset;
struct timeval tm;
time_t prevTime;
if ((s = socket (PF_PACKET, SOCK_PACKET, htons(ETH_P_ARP))) == -1) {
#ifdef IN_BUSYBOX
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LOG(LOG_ERR, bb_msg_can_not_create_raw_socket);
#else
LOG(LOG_ERR, "Could not open raw socket");
#endif
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return -1;
}
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if (setsockopt(s, SOL_SOCKET, SO_BROADCAST, &optval, sizeof(optval)) == -1) {
LOG(LOG_ERR, "Could not setsocketopt on raw socket");
close(s);
return -1;
}
/* send arp request */
memset(&arp, 0, sizeof(arp));
memcpy(arp.h_dest, MAC_BCAST_ADDR, 6); /* MAC DA */
memcpy(arp.h_source, mac, 6); /* MAC SA */
arp.h_proto = htons(ETH_P_ARP); /* protocol type (Ethernet) */
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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 */
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memcpy(arp.sInaddr, &ip, sizeof(ip)); /* source IP address */
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memcpy(arp.sHaddr, mac, 6); /* source hardware address */
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memcpy(arp.tInaddr, &yiaddr, sizeof(yiaddr)); /* target IP address */
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memset(&addr, 0, sizeof(addr));
strcpy(addr.sa_data, interface);
if (sendto(s, &arp, sizeof(arp), 0, &addr, sizeof(addr)) < 0)
rv = 0;
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/* wait arp reply, and check it */
tm.tv_usec = 0;
prevTime = uptime();
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while (timeout > 0) {
FD_ZERO(&fdset);
FD_SET(s, &fdset);
tm.tv_sec = timeout;
if (select(s + 1, &fdset, (fd_set *) NULL, (fd_set *) NULL, &tm) < 0) {
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DEBUG(LOG_ERR, "Error on ARPING request: %m");
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if (errno != EINTR) rv = 0;
} else if (FD_ISSET(s, &fdset)) {
if (recv(s, &arp, sizeof(arp), 0) < 0 ) rv = 0;
if (arp.operation == htons(ARPOP_REPLY) &&
bcmp(arp.tHaddr, mac, 6) == 0 &&
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*((uint32_t *) arp.sInaddr) == yiaddr) {
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DEBUG(LOG_INFO, "Valid arp reply receved for this address");
rv = 0;
break;
}
}
timeout -= uptime() - prevTime;
prevTime = uptime();
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}
close(s);
DEBUG(LOG_INFO, "%salid arp replies for this address", rv ? "No v" : "V");
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return rv;
}