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/***********************************************************************
*
* pppoe-sniff.c
*
* Sniff a network for likely-looking PPPoE frames and deduce the value
* to supply to PPPOE_EXTRA in /etc/ppp/pppoe.conf. USE AT YOUR OWN RISK.
*
* Copyright (C) 2000 by Roaring Penguin Software Inc.
*
* This program may be distributed according to the terms of the GNU
* General Public License, version 2 or (at your option) any later version.
*
***********************************************************************/
static char const RCSID[] =
"$Id$";
#include "pppoe.h"
#ifdef HAVE_GETOPT_H
#include <getopt.h>
#endif
#include <errno.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
#ifdef USE_DLPI
#include <sys/dlpi.h>
/* function declarations */
void dlpromisconreq( int fd, u_long level);
void dlokack(int fd, char *bufp);
#endif
/* Default interface if no -I option given */
#define DEFAULT_IF "eth0"
/* Global vars */
int SeenPADR = 0;
int SeenSess = 0;
UINT16_t SessType, DiscType;
char *IfName = NULL; /* Interface name */
char *ServiceName = NULL; /* Service name */
/**********************************************************************
*%FUNCTION: parsePADRTags
*%ARGUMENTS:
* type -- tag type
* len -- tag length
* data -- tag data
* extra -- extra user data.
*%RETURNS:
* Nothing
*%DESCRIPTION:
* Picks interesting tags out of a PADR packet
***********************************************************************/
void
parsePADRTags(UINT16_t type, UINT16_t len, unsigned char *data,
void *extra)
{
switch(type) {
case TAG_SERVICE_NAME:
ServiceName = malloc(len+1);
if (ServiceName) {
memcpy(ServiceName, data, len);
ServiceName[len] = 0;
}
break;
}
}
/**********************************************************************
*%FUNCTION: fatalSys
*%ARGUMENTS:
* str -- error message
*%RETURNS:
* Nothing
*%DESCRIPTION:
* Prints a message plus the errno value to stderr and exits.
***********************************************************************/
void
fatalSys(char const *str)
{
char buf[1024];
sprintf(buf, "%.256s: %.256s", str, strerror(errno));
printErr(buf);
exit(1);
}
/**********************************************************************
*%FUNCTION: rp_fatal
*%ARGUMENTS:
* str -- error message
*%RETURNS:
* Nothing
*%DESCRIPTION:
* Prints a message to stderr and syslog and exits.
***********************************************************************/
void
rp_fatal(char const *str)
{
printErr(str);
exit(1);
}
/**********************************************************************
*%FUNCTION: usage
*%ARGUMENTS:
* argv0 -- program name
*%RETURNS:
* Nothing
*%DESCRIPTION:
* Prints usage information and exits.
***********************************************************************/
void
usage(char const *argv0)
{
fprintf(stderr, "Usage: %s [options]\n", argv0);
fprintf(stderr, "Options:\n");
fprintf(stderr, " -I if_name -- Specify interface (default %s.)\n",
DEFAULT_IF);
fprintf(stderr, " -V -- Print version and exit.\n");
fprintf(stderr, "\nPPPoE Version %s, Copyright (C) 2000 Roaring Penguin Software Inc.\n", VERSION);
fprintf(stderr, "PPPoE comes with ABSOLUTELY NO WARRANTY.\n");
fprintf(stderr, "This is free software, and you are welcome to redistribute it under the terms\n");
fprintf(stderr, "of the GNU General Public License, version 2 or any later version.\n");
fprintf(stderr, "http://www.roaringpenguin.com\n");
exit(0);
}
#if !defined(USE_LINUX_PACKET) && !defined(USE_DLPI)
int
main()
{
fprintf(stderr, "Sorry, pppoe-sniff works only on Linux.\n");
return 1;
}
#else
/**********************************************************************
*%FUNCTION: main
*%ARGUMENTS:
* argc, argv -- count and values of command-line arguments
*%RETURNS:
* Nothing
*%DESCRIPTION:
* Main program
***********************************************************************/
int
main(int argc, char *argv[])
{
int opt;
int sock;
PPPoEPacket pkt;
int size;
#ifdef USE_DLPI
long buf[MAXDLBUF];
#endif
while((opt = getopt(argc, argv, "I:V")) != -1) {
switch(opt) {
case 'I':
SET_STRING(IfName, optarg);
break;
case 'V':
printf("pppoe-sniff: Roaring Penguin PPPoE Version %s\n", VERSION);
exit(0);
default:
usage(argv[0]);
}
}
/* Pick a default interface name */
if (!IfName) {
IfName = DEFAULT_IF;
}
/* Open the interface */
#ifdef USE_DLPI
sock = openInterface(IfName, Eth_PPPOE_Discovery, NULL);
dlpromisconreq(sock, DL_PROMISC_PHYS);
dlokack(sock, (char *)buf);
dlpromisconreq(sock, DL_PROMISC_SAP);
dlokack(sock, (char *)buf);
#else
sock = openInterface(IfName, ETH_P_ALL, NULL);
#endif
/* We assume interface is in promiscuous mode -- use ifconfig to
ensure this */
fprintf(stderr, "Sniffing for PADR. Start your connection on another machine...\n");
while (!SeenPADR) {
if (receivePacket(sock, &pkt, &size) < 0) continue;
if (ntohs(pkt.length) + HDR_SIZE > size) continue;
if (pkt.ver != 1 || pkt.type != 1) continue;
if (pkt.code != CODE_PADR) continue;
/* Looks promising... parse it */
if (parsePacket(&pkt, parsePADRTags, NULL) < 0) {
continue;
}
DiscType = ntohs(pkt.ethHdr.h_proto);
fprintf(stderr, "\nExcellent! Sniffed a likely-looking PADR.\n");
break;
}
while (!SeenSess) {
if (receivePacket(sock, &pkt, &size) < 0) continue;
if (ntohs(pkt.length) + HDR_SIZE > size) continue;
if (pkt.ver != 1 || pkt.type != 1) continue;
if (pkt.code != CODE_SESS) continue;
/* Cool! */
SessType = ntohs(pkt.ethHdr.h_proto);
break;
}
fprintf(stderr, "Wonderful! Sniffed a likely-looking session packet.\n");
if ((ServiceName == NULL || *ServiceName == 0) &&
DiscType == ETH_PPPOE_DISCOVERY &&
SessType == ETH_PPPOE_SESSION) {
fprintf(stderr, "\nGreat! It looks like a standard PPPoE service.\nYou should not need anything special in the configuration file.\n");
return 0;
}
fprintf(stderr, "\nOK, looks like you need something special in the configuration file.\nTry this:\n\n");
if (ServiceName != NULL && *ServiceName != 0) {
fprintf(stderr, "SERVICENAME='%s'\n", ServiceName);
}
if (DiscType != ETH_PPPOE_DISCOVERY || SessType != ETH_PPPOE_SESSION) {
fprintf(stderr, " PPPOE_EXTRA='-f %x:%x'\n", DiscType, SessType);
}
return 0;
}
#endif
/**********************************************************************
*%FUNCTION: sysErr
*%ARGUMENTS:
* str -- error message
*%RETURNS:
* Nothing
*%DESCRIPTION:
* Prints a message plus the errno value to syslog.
***********************************************************************/
void
sysErr(char const *str)
{
char buf[1024];
sprintf(buf, "%.256s: %.256s", str, strerror(errno));
printErr(buf);
}
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