wrappers.c

/*
 * The ARP Scanner (arp-scan) is Copyright (C) 2005-2019 Roy Hills
 *
 * This file is part of arp-scan.
 *
 * arp-scan is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * arp-scan is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with arp-scan.  If not, see <http://www.gnu.org/licenses/>.
 *
 * Author: Roy Hills
 * Date: 8 November 2003
 *
 * This file contains wrapper functions for system and library calls that
 * are not expected to fail.  If they do fail, then it calls err_sys to
 * print a diagnostic and terminate the program.  This removed the tedious
 * "if ((function()) == NULL) err_sys("function");" logic thus making the
 * code easier to read.
 *
 * The wrapper functions have the same name as the system or library function
 * but with an initial capital letter.  E.g. Gethostbyname().  This convention
 * if from Richard Steven's UNIX Network Programming book.
 *
 */

#include "arp-scan.h"

/*
 * We omit the timezone arg from this wrapper since it's obsolete and we never
 * use it.
 */
int Gettimeofday(struct timeval *tv) {
   int result;

   result = gettimeofday(tv, NULL);

   if (result != 0)
      err_sys("gettimeofday");

   return result;
}

void *Malloc(size_t size) {
   void *result;

   result = malloc(size);

   if (result == NULL)
      err_sys("malloc");

   return result;
}

void *Realloc(void *ptr, size_t size) {
   void *result;

   result=realloc(ptr, size);

   if (result == NULL)
      err_sys("realloc");

   return result;
}

unsigned long int Strtoul(const char *nptr, int base) {
   char *endptr;
   unsigned long int result;

   result=strtoul(nptr, &endptr, base);
   if (endptr == nptr)	/* No digits converted */
      err_msg("ERROR: \"%s\" is not a valid numeric value", nptr);
   if (*endptr != '\0' && !isspace((unsigned char)*endptr))
      err_msg("ERROR: \"%s\" is not a valid numeric value", nptr);

   return result;
}

long int Strtol(const char *nptr, int base) {
   char *endptr;
   long int result;

   result=strtol(nptr, &endptr, base);
   if (endptr == nptr)	/* No digits converted */
      err_msg("ERROR: \"%s\" is not a valid numeric value", nptr);
   if (*endptr != '\0' && !isspace((unsigned char)*endptr))
      err_msg("ERROR: \"%s\" is not a valid numeric value", nptr);

   return result;
}

/*
 * my_lookupdev() is adapted from pcap_lookupdev() which is depreciated
 * in libpcap 1.9.0 and later.
 */
char *
my_lookupdev(char *errbuf)
{
   pcap_if_t *alldevs;

#ifndef IF_NAMESIZE
#define IF_NAMESIZE 8192
#endif

   static char device[IF_NAMESIZE + 1];
   char *ret;

   if (pcap_findalldevs(&alldevs, errbuf) == -1)
      return (NULL);

   if (alldevs == NULL || (alldevs->flags & PCAP_IF_LOOPBACK)) {
   /*
   * There are no devices on the list, or the first device
   * on the list is a loopback device, which means there
   * are no non-loopback devices on the list.  This means
   * we can't return any device.
   */
      (void)strlcpy(errbuf, "no suitable device found", PCAP_ERRBUF_SIZE);
      ret = NULL;
   } else {
   /*
   * Return the name of the first device on the list.
   */
      (void)strlcpy(device, alldevs->name, sizeof(device));
      ret = device;
   }

   pcap_freealldevs(alldevs);
   return (ret);
}