arpping.c File Reference

#include <sys/types.h>
#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 <stdio.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include "dhcpd.h"
#include "debug.h"
#include "arpping.h"

Include dependency graph for arpping.c:

Go to the source code of this file.

Functions

int arpping (u_int32_t yiaddr, u_int32_t ip, unsigned char *mac, char *interface)


Function Documentation

int arpping ( u_int32_t  yiaddr,
u_int32_t  ip,
unsigned char *  mac,
char *  interface 
)

Definition at line 35 of file arpping.c.

References DEBUG, LOG, LOG_ERR, LOG_INFO, and MAC_BCAST_ADDR.

00036 {
00037 
00038         int     timeout = 2;
00039         int     optval = 1;
00040         int     s;                      /* socket */
00041         int     rv = 1;                 /* return value */
00042         struct sockaddr addr;           /* for interface name */
00043         struct arpMsg   arp;
00044         fd_set          fdset;
00045         struct timeval  tm;
00046         time_t          prevTime;
00047 
00048 
00049         if ((s = socket (PF_PACKET, SOCK_PACKET, htons(ETH_P_ARP))) == -1) {
00050                 LOG(LOG_ERR, "Could not open raw socket");
00051                 return -1;
00052         }
00053         
00054         if (setsockopt(s, SOL_SOCKET, SO_BROADCAST, &optval, sizeof(optval)) == -1) {
00055                 LOG(LOG_ERR, "Could not setsocketopt on raw socket");
00056                 close(s);
00057                 return -1;
00058         }
00059 
00060         /* send arp request */
00061         memset(&arp, 0, sizeof(arp));
00062         memcpy(arp.ethhdr.h_dest, MAC_BCAST_ADDR, 6);   /* MAC DA */
00063         memcpy(arp.ethhdr.h_source, mac, 6);            /* MAC SA */
00064         arp.ethhdr.h_proto = htons(ETH_P_ARP);          /* protocol type (Ethernet) */
00065         arp.htype = htons(ARPHRD_ETHER);                /* hardware type */
00066         arp.ptype = htons(ETH_P_IP);                    /* protocol type (ARP message) */
00067         arp.hlen = 6;                                   /* hardware address length */
00068         arp.plen = 4;                                   /* protocol address length */
00069         arp.operation = htons(ARPOP_REQUEST);           /* ARP op code */
00070         *((u_int *) arp.sInaddr) = ip;                  /* source IP address */
00071         memcpy(arp.sHaddr, mac, 6);                     /* source hardware address */
00072         *((u_int *) arp.tInaddr) = yiaddr;              /* target IP address */
00073         
00074         memset(&addr, 0, sizeof(addr));
00075         strcpy(addr.sa_data, interface);
00076         if (sendto(s, &arp, sizeof(arp), 0, &addr, sizeof(addr)) < 0)
00077                 rv = 0;
00078         
00079         /* wait arp reply, and check it */
00080         tm.tv_usec = 0;
00081         time(&prevTime);
00082         while (timeout > 0) {
00083                 FD_ZERO(&fdset);
00084                 FD_SET(s, &fdset);
00085                 tm.tv_sec = timeout;
00086                 if (select(s + 1, &fdset, (fd_set *) NULL, (fd_set *) NULL, &tm) < 0) {
00087                         DEBUG(LOG_ERR, "Error on ARPING request: %s", strerror(errno));
00088                         if (errno != EINTR) rv = 0;
00089                 } else if (FD_ISSET(s, &fdset)) {
00090                         if (recv(s, &arp, sizeof(arp), 0) < 0 ) rv = 0;
00091                         if (arp.operation == htons(ARPOP_REPLY) && 
00092                             bcmp(arp.tHaddr, mac, 6) == 0 && 
00093                             *((u_int *) arp.sInaddr) == yiaddr) {
00094                                 DEBUG(LOG_INFO, "Valid arp reply receved for this address");
00095                                 rv = 0;
00096                                 break;
00097                         }
00098                 }
00099                 timeout -= time(NULL) - prevTime;
00100                 time(&prevTime);
00101         }
00102         close(s);
00103         DEBUG(LOG_INFO, "%salid arp replies for this address", rv ? "No v" : "V");       
00104         return rv;
00105 }


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