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// epp_tun.c - Ethernet Protocol Program for TUN/TAP interface
//
// Copyright (c) 2002, Timothy M. Stark
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
// TIMOTHY M STARK BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
// IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
// CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
// Except as contained in this notice, the name of Timothy M Stark shall not
// be used in advertising or otherwise to promote the sale, use or other
// dealings in this Software without prior written authorization from
// Timothy M Stark.
#include <stdio.h>
#include <strings.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>
#include <linux/ioctl.h>
#include <linux/if.h>
#include <linux/if_tun.h>
#include "epp.h"
typedef unsigned char uchar;
void Usage(char *pgmName)
{
printf("Usage: %s <tap|tun>\n", pgmName);
}
void DumpPacket(uchar *pkt, int len)
{
uchar ascBuffer[17];
uchar ch, *pasc;
int idxAddr, idx;
// Display Ethernet Head Information
printf("Ethernet %02X:%02X:%02X:%02X:%02X:%02X to %02X:%02X:%02X:%02X:%02X:%02X, type %04X\n",
pkt[6], pkt[7], pkt[8], pkt[9], pkt[10], pkt[11], // Source
pkt[0], pkt[1], pkt[2], pkt[3], pkt[4], pkt[5], // Destination
(pkt[12] << 8) | pkt[13]); // Type
// Display Ethernet Data Information
for (idxAddr = 14; idxAddr < len;) {
printf("%04X: ", idxAddr - 14);
pasc = ascBuffer;
for (idx = 0; (idx < 16) && (idxAddr < len); idx++) {
ch = pkt[idxAddr++];
printf("%c%02X", (idx == 8) ? '-' : ' ', ch);
*pasc++ = ((ch >= 32) && (ch < 127)) ? ch : '.';
}
for (; idx < 16; idx++)
printf(" ");
*pasc = '\0';
printf(" |%-16s|\n", ascBuffer);
}
}
int OpenTUN(char *tunName)
{
struct ifreq ifr; // Interface Requests
int tunFlags; // Interface Flags
int tun; // TUN/TAP Socket
int err; // Error Flag
if (!strcmp(tunName, "tap"))
tunFlags = IFF_TAP;
else if (!strcmp(tunName, "tun"))
tunFlags = IFF_TUN;
else
return EPP_TUN_INVALID;
if ((tun = open("/dev/net/tun", O_RDWR)) < 0)
return tun;
// Set up interface flags
memset(&ifr, 0, sizeof(ifr));
sprintf(ifr.ifr_name, "%s%%d", tunName);
ifr.ifr_flags = tunFlags|IFF_NO_PI;
// Send interface requests to TUN/TAP driver.
if ((err = ioctl(tun, TUNSETIFF, &ifr)) < 0)
return err;
strcpy(tunName, ifr.ifr_name);
return tun;
}
int main(int argc, char **argv)
{
char tunName[40];
int tun;
uchar frame[2048];
int len = 2048;
int rc;
strcpy(tunName, argv[1]);
tun = OpenTUN(tunName);
switch(tun) {
case EPP_TUN_IOERROR:
printf("%s: Can't open %s: %s\n",
argv[0], tunName, strerror(errno));
return 1;
case EPP_TUN_INVALID:
Usage(argv[0]);
return 2;
default:
printf("Successful! %s\n", tunName);
break;
}
// Test TUN/TAP interface (temp)
printf("Ok, listening...\n");
while(1) {
if ((rc = read(tun, frame, len)) < 0) {
printf("Error: %s\n", strerror(errno));
exit(1);
}
DumpPacket(frame, rc);
}
}
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