Obtaining advanced information about installed devices

Lesson 1 (Obtaining the device list) demonstrated how to get basic information (i.e. device name and description) about available adapters. Actually, WinPcap provides also other advanced information. In particular, every pcap_if structure returned by pcap_findalldevs_ex() contains also a list of pcap_addr structures, with:

Additionally, pcap_findalldevs_ex() can also return remote adapters and a list of pcap files that are located in a given local folder.

The following sample provides an ifprint() function that prints the complete contents of a pcap_if structure. It is invoked by the program for every entry returned by pcap_findalldevs_ex().

/*
 * Copyright (c) 1999 - 2005 NetGroup, Politecnico di Torino (Italy)
 * Copyright (c) 2005 - 2006 CACE Technologies, Davis (California)
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the Politecnico di Torino, CACE Technologies 
 * nor the names of its contributors may be used to endorse or promote 
 * products derived from this software without specific prior written 
 * permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

#include <stdio.h>

#include "pcap.h"

#ifndef WIN32
    #include <sys/socket.h>
    #include <netinet/in.h>
#else
    #include <winsock.h>
#endif


// Function prototypes
void ifprint(pcap_if_t *d);
char *iptos(u_long in);
char* ip6tos(struct sockaddr *sockaddr, char *address, int addrlen);


int main()
{
  pcap_if_t *alldevs;
  pcap_if_t *d;
  char errbuf[PCAP_ERRBUF_SIZE+1];
  char source[PCAP_ERRBUF_SIZE+1];

  printf("Enter the device you want to list:\n"
            "rpcap://              ==> lists interfaces in the local machine\n"
            "rpcap://hostname:port ==> lists interfaces in a remote machine\n"
            "                          (rpcapd daemon must be up and running\n"
            "                           and it must accept 'null' authentication)\n"
            "file://foldername     ==> lists all pcap files in the give folder\n\n"
            "Enter your choice: ");

  fgets(source, PCAP_ERRBUF_SIZE, stdin);
  source[PCAP_ERRBUF_SIZE] = '\0';

  /* Retrieve the interfaces list */
  if (pcap_findalldevs_ex(source, NULL, &alldevs, errbuf) == -1)
  {
    fprintf(stderr,"Error in pcap_findalldevs: %s\n",errbuf);
    exit(1);
  }

  /* Scan the list printing every entry */
  for(d=alldevs;d;d=d->next)
  {
    ifprint(d);
  }

  pcap_freealldevs(alldevs);

  return 1;
}



/* Print all the available information on the given interface */
void ifprint(pcap_if_t *d)
{
  pcap_addr_t *a;
  char ip6str[128];

  /* Name */
  printf("%s\n",d->name);

  /* Description */
  if (d->description)
    printf("\tDescription: %s\n",d->description);

  /* Loopback Address*/
  printf("\tLoopback: %s\n",(d->flags & PCAP_IF_LOOPBACK)?"yes":"no");

  /* IP addresses */
  for(a=d->addresses;a;a=a->next) {
    printf("\tAddress Family: #%d\n",a->addr->sa_family);
  
    switch(a->addr->sa_family)
    {
      case AF_INET:
        printf("\tAddress Family Name: AF_INET\n");
        if (a->addr)
          printf("\tAddress: %s\n",iptos(((struct sockaddr_in *)a->addr)->sin_addr.s_addr));
        if (a->netmask)
          printf("\tNetmask: %s\n",iptos(((struct sockaddr_in *)a->netmask)->sin_addr.s_addr));
        if (a->broadaddr)
          printf("\tBroadcast Address: %s\n",iptos(((struct sockaddr_in *)a->broadaddr)->sin_addr.s_addr));
        if (a->dstaddr)
          printf("\tDestination Address: %s\n",iptos(((struct sockaddr_in *)a->dstaddr)->sin_addr.s_addr));
        break;

      case AF_INET6:
        printf("\tAddress Family Name: AF_INET6\n");
        if (a->addr)
          printf("\tAddress: %s\n", ip6tos(a->addr, ip6str, sizeof(ip6str)));
       break;

      default:
        printf("\tAddress Family Name: Unknown\n");
        break;
    }
  }
  printf("\n");
}



/* From tcptraceroute, convert a numeric IP address to a string */
#define IPTOSBUFFERS    12
char *iptos(u_long in)
{
    static char output[IPTOSBUFFERS][3*4+3+1];
    static short which;
    u_char *p;

    p = (u_char *)&in;
    which = (which + 1 == IPTOSBUFFERS ? 0 : which + 1);
    _snprintf_s(output[which], sizeof(output[which]), sizeof(output[which]),"%d.%d.%d.%d", p[0], p[1], p[2], p[3]);
    return output[which];
}

char* ip6tos(struct sockaddr *sockaddr, char *address, int addrlen)
{
    socklen_t sockaddrlen;

    #ifdef WIN32
    sockaddrlen = sizeof(struct sockaddr_in6);
    #else
    sockaddrlen = sizeof(struct sockaddr_storage);
    #endif


    if(getnameinfo(sockaddr, 
        sockaddrlen, 
        address, 
        addrlen, 
        NULL, 
        0, 
        NI_NUMERICHOST) != 0) address = NULL;

    return address;
}

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documentation. Copyright (c) 2002-2005 Politecnico di Torino. Copyright (c) 2005-2008 CACE Technologies. All rights reserved.