tcpip.txt

本文目的是演示Linux中的SOCK_PACKET插口的使用方法

/*

* This program demonstrate SOCK_PACK call.

* Thanks Linux. Thanks Alan Cox

* derived from/usr/src/redhat/SOURCES/dosemu-0.66.7/src/dosext/net/net/libpacket.c

*　 compile method： cc capturer.c -o capturer

*/

/* 

* Alan Cox raw code 

*/


/*

* SOCK_PACKET support.

* Placed under the GNU LGPL.

*

* First cut at a library of handy support routines. Comments, additions

* and bug fixes greatfully received.

*

* (c) 1994 Alan Cox [e-mail] GW4PTS@GB7SWN

*/

#include <stdio.h>

#include <features.h>

#include <unistd.h>

#include <stdlib.h>

#include <ctype.h>

#include <getopt.h>

#include <string.h>

#include <fcntl.h>

#include <asm/types.h>

#include <sys/socket.h>

#include <sys/ioctl.h>

/*#if __GLIBC__ > 1*/

#include <asm/sockios.h>

#include <net/if.h>

/*#else

#include <linux/sockios.h>

#include <linux/if.h>

#endif*/

#include <netinet/in.h>

#include <asm/checksum.h>

/*

* Obtain a file handle on a raw ethernet type. In actual fact

* you can also request the dummy types for AX.25 or 802.3 also

*

* -1 indicates an error

* 0 or higher is a file descriptor which we have set non blocking

*

* WARNING: It is ok to listen to a service the system is using (eg arp)

* but don't try and run a user mode stack on the same service or all

* hell will break loose.

*/

int 

OpenNetworkType(unsigned short netid)

{

int s = socket(AF_INET, SOCK_PACKET, htons(netid));


if (s == -1)

return -1;

fcntl(s, F_SETFL, O_NDELAY);

return s;

}


/*

* Close a file handle to a raw packet type.

*/


void 

CloseNetworkLink(int sock)

{

close(sock);

}


/*

* Write a packet to the network. You have to give a device to

* this function. This is a device name (eg 'eth0' for the first

* ethernet card). Please don't assume eth0, make it configurable

* - plip is ethernet like but not eth0, ditto for the de600's.

*

* Return: -1 is an error

* otherwise bytes written.

*/

int 

WriteToNetwork(int sock, const char *device, const char *data, int len)

{

struct sockaddr sa;

sa.sa_family = AF_INET;

strcpy(sa.sa_data, device);

return (sendto(sock, data, len, 0, &sa, sizeof(sa)));

}

/*

* Read a packet from the network. The device parameter will

* be filled in by this routine (make it 32 bytes or more).

* If you wish to work with one interface only you must filter

* yourself. Remember to make your buffer big enough for your

* data. Oversized packets will be truncated.

*

* Return:

* -1 Error

* otherwise Size of packet received.

*/

int 

ReadFromNetwork(int sock, char *device, char *data, int len)

{

struct sockaddr sa;

int sz = sizeof(sa);

int error;

error = recvfrom(sock, data, len, 0, &sa, &sz);

if (error == -1)

return -1;

strcpy(device, sa.sa_data);

return error; /* Actually size of received packet */

}

/*

* Handy support routines.

*/

/*

* Obtain the hardware address of an interface.

* addr should be a buffer of 8 bytes or more.

*

* Return:

* 0 Success, buffer holds data.

* -1 Error.

*/


/*

* NET2 or NET3 - work for both.

*/

#if defined(OLD_SIOCGIFHWADDR) || (KERNEL_VERSION >= 1003038)

#define NET3

#endif


int 

GetDeviceHardwareAddress(char *device, char *addr)

{

int s = socket(AF_INET, SOCK_DGRAM, 0);

struct ifreq req;

int err;

strcpy(req.ifr_name, device);

err = ioctl(s, SIOCGIFHWADDR, &req); 

close(s); /* Thanks Rob. for noticing this */

if (err == -1)

return err;

memcpy(addr, req.ifr_hwaddr.sa_data,8);

return 0;

}

/*

* Obtain the maximum packet size on an interface.

*

* Return:

* >0 Return is the mtu of the interface

* -1 Error.

*/

int 

GetDeviceMTU(char *device)

{

int s = socket(AF_INET, SOCK_DGRAM, 0);

struct ifreq req;

int err;

strcpy(req.ifr_name, device);

err = ioctl(s, SIOCGIFMTU, &req);

close(s); /* So I'll add this one as well. Ok Alan? - Rob */

if (err == -1)

return err;

return req.ifr_mtu;

}

#define data_packet_len 1514

int

main(int argc ,char *argv[])

{

char devicename_rec[32];

unsigned char data[data_packet_len];

int netid=0x03,sock_h=0,i=0,count_rec=0;

if ((sock_h=OpenNetworkType(netid))<0)

{

printf("Can't open net_dectype %d \n",netid);

return -1;

}

printf("Ready to receive 0x%x data packet...\n",netid); 

for(;;) { 

if (ReadFromNetwork(sock_h,devicename_rec,data,data_packet_len)>0) {

printf("Received Packet = %d\n",++count_rec) ;

for (i=0;i<100;i++)

printf("%2x|",data[i]);

printf("\n");

} 

}

}