经过几天的艰苦工作;我在winpcap库教程的基础上编写了这个程序;它捕获数据包,过滤数据包并绘制接收到的数据:
/*
* 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.
*
*/
#define HAVE_REMOTE
#include "pcap.h"
#include "winsock2.h "
/* 4 bytes IP address */
typedef struct ip_address{
u_char byte1;
u_char byte2;
u_char byte3;
u_char byte4;
}ip_address;
/* IPv4 header */
typedef struct ip_header{
u_char ver_ihl; // Version (4 bits) + Internet header length (4 bits)
u_char tos; // Type of service
u_short tlen; // Total length
u_short identification; // Identification
u_short flags_fo; // Flags (3 bits) + Fragment offset (13 bits)
u_char ttl; // Time to live
u_char proto; // Protocol
u_short crc; // Header checksum
ip_address saddr; // Source address
ip_address daddr; // Destination address
u_int op_pad; // Option + Padding
}ip_header;
/* UDP header*/
typedef struct udp_header{
u_short sport; // Source port
u_short dport; // Destination port
u_short len; // Datagram length
u_short crc; // Checksum
}udp_header;
/* prototype of the packet handler */
void packet_handler(u_char *param, const struct pcap_pkthdr *header, const u_char *pkt_data);
main()
{
pcap_if_t *alldevs;
pcap_if_t *d;
int inum;
int i=0;
pcap_t *adhandle;
char errbuf[PCAP_ERRBUF_SIZE];
u_int netmask;
char packet_filter[] = "ip and udp";
struct bpf_program fcode;
/* Retrieve the device list */
if (pcap_findalldevs_ex(PCAP_SRC_IF_STRING, NULL, &alldevs, errbuf) == -1)
{
fprintf(stderr,"Error in pcap_findalldevs: %s\n", errbuf);
exit(1);
}
/* Print the list */
for(d=alldevs; d; d=d->next)
{
printf("%d. %s", ++i, d->name);
if (d->description)
printf(" (%s)\n", d->description);
else
printf(" (No description available)\n");
}
if(i==0)
{
printf("\nNo interfaces found! Make sure WinPcap is installed.\n");
return -1;
}
printf("Enter the interface number (1-%d):",i);
scanf("%d", &inum);
if(inum < 1 || inum > i)
{
printf("\nInterface number out of range.\n");
/* Free the device list */
pcap_freealldevs(alldevs);
return -1;
}
/* Jump to the selected adapter */
for(d=alldevs, i=0; i< inum-1 ;d=d->next, i++);
/* Open the adapter */
if ( (adhandle= pcap_open(d->name, // name of the device
65536, // portion of the packet to capture.
// 65536 grants that the whole packet will be captured on all the MACs.
PCAP_OPENFLAG_PROMISCUOUS, // promiscuous mode
1000, // read timeout
NULL, // remote authentication
errbuf // error buffer
) ) == NULL)
{
fprintf(stderr,"\nUnable to open the adapter. %s is not supported by WinPcap\n");
/* Free the device list */
pcap_freealldevs(alldevs);
return -1;
}
/* Check the link layer. We support only Ethernet for simplicity. */
if(pcap_datalink(adhandle) != DLT_EN10MB)
{
fprintf(stderr,"\nThis program works only on Ethernet networks.\n");
/* Free the device list */
pcap_freealldevs(alldevs);
return -1;
}
if(d->addresses != NULL)
/* Retrieve the mask of the first address of the interface */
netmask=((struct sockaddr_in *)(d->addresses->netmask))->sin_addr.S_un.S_addr;
else
/* If the interface is without addresses we suppose to be in a C class network */
netmask=0xffffff;
//compile the filter
if (pcap_compile(adhandle, &fcode, packet_filter, 1, netmask) <0 )
{
fprintf(stderr,"\nUnable to compile the packet filter. Check the syntax.\n");
/* Free the device list */
pcap_freealldevs(alldevs);
return -1;
}
//set the filter
if (pcap_setfilter(adhandle, &fcode)<0)
{
fprintf(stderr,"\nError setting the filter.\n");
/* Free the device list */
pcap_freealldevs(alldevs);
return -1;
}
printf("\nlistening on %s...\n", d->description);
/* At this point, we don't need any more the device list. Free it */
pcap_freealldevs(alldevs);
/* start the capture */
pcap_loop(adhandle, 0, packet_handler, NULL);
return 0;
}
/* Callback function invoked by libpcap for every incoming packet */
void packet_handler(u_char *param, const struct pcap_pkthdr *header, const u_char *pkt_data)
{
struct tm *ltime;
char timestr[16];
ip_header *ih;
udp_header *uh;
u_int ip_len;
u_short sport,dport;
time_t local_tv_sec;
/* convert the timestamp to readable format */
local_tv_sec = header->ts.tv_sec;
ltime=localtime(&local_tv_sec);
strftime( timestr, sizeof timestr, "%H:%M:%S", ltime);
/* print timestamp and length of the packet */
printf("%s.%.6d len:%d ", timestr, header->ts.tv_usec, header->len);
/* retrieve the position of the ip header */
ih = (ip_header *) (pkt_data +
14); //length of ethernet header
/* retrieve the position of the udp header */
ip_len = (ih->ver_ihl & 0xf) * 4;
uh = (udp_header *) ((u_char*)ih + ip_len);
/* convert from network byte order to host byte order */
sport = ntohs( uh->sport );
dport = ntohs( uh->dport );
/* print ip addresses and udp ports */
printf("%d.%d.%d.%d.%d -> %d.%d.%d.%d.%d\n",
ih->saddr.byte1,
ih->saddr.byte2,
ih->saddr.byte3,
ih->saddr.byte4,
sport,
ih->daddr.byte1,
ih->daddr.byte2,
ih->daddr.byte3,
ih->daddr.byte4,
dport);
}
