/* -*- Mode: c; tab-width: 4; indent-tabs-mode: 1; c-basic-offset: 4; -*- */

/* vim:set ts=4 sw=4 ai nobackup nocindent sm: */

/*

* tcptraceroute -- A traceroute implementation using TCP packets

* Copyright (c) 2001-2006 Michael C. Toren <mct@toren.net>

*

* This program is free software; you can redistribute it and/or modify it

* under the terms of the GNU General Public License, version 2, as published

* by the Free Software Foundation.

*

* This program is distributed in the hope that it will be useful, but

* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY

* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License

* for more details.

*

* A copy of the GNU GPL is available as /usr/doc/copyright/GPL on Debian

* systems, or on the World Wide Web at http://www.gnu.org/copyleft/gpl.html

* You can also obtain it by writing to the Free Software Foundation, Inc.,

* 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA

*/

#include "tcptraceroute.h"

#ifndef SIOCGIFCONF

#include <sys/sockio.h> /* Solaris, maybe others? */

#endif

#ifndef AF_LINK

#define AF_LINK AF_INET /* BSD defines some AF_INET interfaces as AF_LINK */

#endif

struct interface_entry *interfaces;

/*

* To add support for additional link layers add entries to the following

* table. The numbers below are believed to be correct and were obtained

* by looking through other pcap programs, however tcptraceroute has only

* been well tested on ethernet, PPP, and loopback interfaces.

*/

struct datalinktype datalinktypes[] = {

/* type offset name */

#ifdef DLT_RAW

{ DLT_RAW, 0, "RAW" },

#endif

#ifdef DLT_EN10MB

{ DLT_EN10MB, 14, "ETHERNET" },

#endif

#ifdef DLT_PPP

{ DLT_PPP, 4, "PPP" },

#endif

#ifdef DLT_LINUX_SLL

{ DLT_LINUX_SLL, 16, "PPP_HDLC" },

#endif

#ifdef DLT_SLIP

{ DLT_SLIP, 16, "SLIP" },

#endif

#ifdef DLT_PPP_BSDOS

{ DLT_PPP_BSDOS, 24, "PPP_BSDOS" },

#endif

#ifdef DLT_SLIP_BSDOS

{ DLT_SLIP_BSDOS, 24, "SLIP_BSDOS" },

#endif

#ifdef DLT_FDDI

{ DLT_FDDI, 21, "FDDI" },

#endif

#ifdef DLT_IEEE802

{ DLT_IEEE802, 22, "IEEE802" },

#endif

#ifdef DLT_NULL

{ DLT_NULL, 4, "DLT_NULL" },

#endif

#ifdef DLT_LOOP

{ DLT_LOOP, 4, "DLT_LOOP" },

#endif

#ifdef DLT_PPP_ETHER

{ DLT_PPP_ETHER, 12, "PPP_ETHER" },

#endif

/* Does anyone know correct values for these? */

#ifdef DLT_ATM_RFC1483

{ DLT_ATM_RFC1483, -1, "ATM_RFC1483" },

#endif

#ifdef DLT_EN3MB

{ DLT_EN3MB, -1, "EN3MB" },

#endif

#ifdef DLT_AX25

{ DLT_AX25, -1, "AX25" },

#endif

#ifdef DLT_PRONET

{ DLT_PRONET, -1, "PRONET" },

#endif

#ifdef DLT_CHAOS

{ DLT_CHAOS, -1, "CHAOS" },

#endif

#ifdef DLT_ARCNET

{ DLT_ARCNET, -1, "ARCNET" },

#endif

/* End of the road */

{ -1, -1, NULL }

};

int datalinkoffset(int type)

{

int i;

for (i = 0; datalinktypes[i].name; i++)

if (datalinktypes[i].type == type)

return datalinktypes[i].offset;

return -1;

}

char *datalinkname(int type)

{

static char name[TEXTSIZE];

int i;

for (i = 0; datalinktypes[i].name; i++)

if (datalinktypes[i].type == type)

return datalinktypes[i].name;

safe_snprintf(name, TEXTSIZE, "#%d", type);

return name;

}

/*

* Fetches the interface list, storing it in struct interface_entry interfaces.

*/

void getinterfaces(void)

{

struct interface_entry *p;

struct ifconf ifc;

struct ifreq *ifrp, ifr;

int numreqs, i, s;

u_long addr;

int salen;

char *x;

debug("entering getinterfaces()\n");

if (o_nogetinterfaces)

{

debug("Not fetching the interface list\n");

return;

}

if (interfaces)

fatal("Double call to getinterfaces()\n");

ifc.ifc_buf = NULL;

p = NULL;

numreqs = 32;

if ((s = socket(AF_INET, SOCK_DGRAM, 0)) < 0)

fatal("socket error");

debug("ifreq buffer set to %d\n", numreqs);

for (;;)

{

ifc.ifc_len = sizeof(struct ifreq) * numreqs;

ifc.ifc_buf = xrealloc(ifc.ifc_buf, ifc.ifc_len);

if (ioctl(s, SIOCGIFCONF, &ifc) < 0)

pfatal("ioctl");

/* This "+ sizeof(struct ifreq) + 64" crap seems to be an (Open?)BSDism. */

if ( (ifc.ifc_len + sizeof(struct ifreq) + 64) >= (sizeof(struct ifreq) * numreqs) )

{

/* Assume it overflowed and try again */

numreqs += 32;

if (numreqs > 20000)

break; /* Too big! */

debug("ifreq buffer grown to %d\n", numreqs);

continue;

}

break;

}

debug("Successfully retrieved interface list\n");

#ifdef HAVE_SOCKADDR_SA_LEN

debug("Using HAVE_SOCKADDR_SA_LEN method for finding addresses.\n");

#endif

for (x = ifc.ifc_buf; x < (ifc.ifc_buf + ifc.ifc_len); x += salen)

{

ifrp = (struct ifreq *)x;

memset(&ifr, 0, sizeof(struct ifreq));

strcpy(ifr.ifr_name, ifrp->ifr_name);

#ifdef HAVE_SOCKADDR_SA_LEN

salen = sizeof(ifrp->ifr_name) + ifrp->ifr_addr.sa_len;

if (salen < sizeof(*ifrp))

salen = sizeof(*ifrp);

addr = ((struct sockaddr_in *)&ifrp->ifr_addr)->sin_addr.s_addr;

if (ioctl(s, SIOCGIFFLAGS, &ifr) < 0)

pfatal("ioctl(SIOCGIFFLAGS)");

#else /* HAVE_SOCKADDR_SA_LEN */

salen = sizeof(*ifrp);

if (ioctl(s, SIOCGIFADDR, &ifr) < 0)

{

debug("ioctl(SIOCGIFADDR) on unconfigured interface %s failed; skipping\n",

sprintable(ifr.ifr_name));

continue;

}

addr = ((struct sockaddr_in *)&ifr.ifr_addr)->sin_addr.s_addr;

#endif /* HAVE_SOCKADDR_SA_LEN else */

#ifdef AF_INET6

if (ifrp->ifr_addr.sa_family == AF_INET6)

{

debug("Ignoring AF_INET6 address on interface %s\n",

sprintable(ifr.ifr_name));

continue;

}

#endif

if (ifrp->ifr_addr.sa_family != AF_INET &&

ifrp->ifr_addr.sa_family != AF_LINK)

{

debug("Ignoring non-AF_INET address on interface %s\n",

sprintable(ifr.ifr_name));

continue;

}

if (ioctl(s, SIOCGIFFLAGS, &ifr) < 0)

pfatal("ioctl(SIOCGIFFLAGS)");

if ((ifr.ifr_flags & IFF_UP) == 0)

{

debug("Ignoring down interface %s\n",

sprintable(ifr.ifr_name));

continue;

}

/* Deal with virtual hosts */

for (i = 0; ifr.ifr_name[i]; i++)

if (ifr.ifr_name[i] == ':')

ifr.ifr_name[i] = '\0';

/* Grow another node on the linked list... */

if (!p)

p = interfaces = xrealloc(NULL, sizeof(struct interface_entry));

else

p = p->next = xrealloc(NULL, sizeof(struct interface_entry));

p->next = NULL;

/* ... and fill it in */

p->addr = addr;

p->name = xrealloc(NULL, strlen(ifr.ifr_name) + 1);

strcpy(p->name, ifr.ifr_name);

debug("Discovered interface %s with address %s\n",

sprintable(p->name), iptos(p->addr));

}

free(ifc.ifc_buf);

debug("leaving getinterfaces()\n");

}

/*

* Determines the source address that should be used to reach the

* given destination address.

*/

u_long findsrc(u_long dest)

{

struct sockaddr_in sinsrc, sindest;

int s, size;

if ((s = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) < 0)

pfatal("socket error");

memset(&sinsrc, 0, sizeof(struct sockaddr_in));

memset(&sindest, 0, sizeof(struct sockaddr_in));

sindest.sin_family = AF_INET;

sindest.sin_addr.s_addr = dest;

sindest.sin_port = htons(53); /* can be anything but zero */

if (connect(s, (struct sockaddr *)&sindest, sizeof(sindest)) < 0)

pfatal("connect");

size = sizeof(sinsrc);

if (getsockname(s, (struct sockaddr *)&sinsrc, &size) < 0)

pfatal("getsockname");

close(s);

debug("Determined source address of %s to reach %s\n",

iptos(sinsrc.sin_addr.s_addr), iptos(dest));

return sinsrc.sin_addr.s_addr;

}

/*

* Find an appropriate device to use given the specified source address.

* However, if we find an interface matching the global dst_ip address, set

* the source address we're looking for to 127.0.0.1 in an attempt to select

* the loopback. Ofcourse, this entirely depends on the fact that a loopback

* interface exists with an address of 127.0.0.1.

*/

char *finddev(u_long with_src)

{

struct interface_entry *p;

char *device = NULL;

debug("entering finddev()\n");

/* First, see if we're trying to trace to ourself */

for (p = interfaces; p; p = p->next)

if (p->addr == dst_ip)

{

debug("Destination matches local address of interface %s;\n\tattempting to find loopback interface, o_nofilter set\n", p->name);

with_src = hosttoip("127.0.0.1", LIBNET_DONT_RESOLVE);

o_nofilter = 1;

}

for (p = interfaces; p; p = p->next)

if (p->addr == with_src)

device = p->name;

debug("finddev() returning %s\n", device);

return device;

}