WinPcap 4.1.3
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;
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)
{
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;
}
struct pcap_if pcap_if_t
Item in a list of interfaces, see pcap_if.
Definition incs/pcap.h:72
#define PCAP_IF_LOOPBACK
interface is loopback
Definition incs/pcap.h:156
#define PCAP_ERRBUF_SIZE
Size to use when allocating the buffer that contains the libpcap errors.
Definition incs/pcap.h:59
struct pcap_addr pcap_addr_t
Representation of an interface address, see pcap_addr.
Definition incs/pcap.h:73
void pcap_freealldevs(pcap_if_t *alldevsp)
Free an interface list returned by pcap_findalldevs().
int pcap_findalldevs_ex(char *source, struct pcap_rmtauth *auth, pcap_if_t **alldevs, char *errbuf)
Create a list of network devices that can be opened with pcap_open().
struct sockaddr * broadaddr
if not NULL, a pointer to a struct sockaddr that contains the broadcast address corre­ sponding to th...
Definition incs/pcap.h:165
struct sockaddr * addr
a pointer to a struct sockaddr containing an address
Definition incs/pcap.h:163
struct sockaddr * dstaddr
if not NULL, a pointer to a struct sockaddr that contains the destination address corre­ sponding to ...
Definition incs/pcap.h:166
struct pcap_addr * next
if not NULL, a pointer to the next element in the list; NULL for the last element of the list
Definition incs/pcap.h:162
struct sockaddr * netmask
if not NULL, a pointer to a struct sockaddr that contains the netmask corresponding to the address po...
Definition incs/pcap.h:164
u_int flags
PCAP_IF_ interface flags. Currently the only possible flag is PCAP_IF_LOOPBACK, that is set if the in...
Definition incs/pcap.h:153
struct pcap_addr * addresses
a pointer to the first element of a list of addresses for the interface
Definition incs/pcap.h:152
char * name
a pointer to a string giving a name for the device to pass to pcap_open_live()
Definition incs/pcap.h:150
struct pcap_if * next
if not NULL, a pointer to the next element in the list; NULL for the last element of the list
Definition incs/pcap.h:149
char * description
if not NULL, a pointer to a string giving a human-readable description of the device
Definition incs/pcap.h:151

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documentation. Copyright (c) 2002-2005 Politecnico di Torino. Copyright (c) 2005-2010 CACE Technologies. Copyright (c) 2010-2013 Riverbed Technology. All rights reserved.