netdissect.c - platform/external/tcpdump - Git at Google

 /*
  * Copyright (c) 1988-1997
  *	The Regents of the University of California.  All rights reserved.
  *
  * Copyright (c) 1998-2012  Michael Richardson <[email protected]>
  *      The TCPDUMP project
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that: (1) source code distributions
  * retain the above copyright notice and this paragraph in its entirety, (2)
  * distributions including binary code include the above copyright notice and
  * this paragraph in its entirety in the documentation or other materials
  * provided with the distribution, and (3) all advertising materials mentioning
  * features or use of this software display the following acknowledgement:
  * ``This product includes software developed by the University of California,
  * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
  * the University 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 ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
  * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  */

 #ifdef HAVE_CONFIG_H
 #include <config.h>
 #endif

 #include "netdissect-stdinc.h"
 #include "netdissect.h"
 #include <string.h>
 #include <stdio.h>
 #include <stdlib.h>

 #ifdef USE_LIBSMI
 #include <smi.h>
 #endif

 /*
  * Initialize anything that must be initialized before dissecting
  * packets.
  *
  * This should be called at the beginning of the program; it does
  * not need to be called, and should not be called, for every
  * netdissect_options structure.
  */
 int
 nd_init(char *errbuf, size_t errbuf_size)
 {
 #ifdef _WIN32
 	WORD wVersionRequested;
 	WSADATA wsaData;
 	int err;

 	/*
 	 * Request Winsock 2.2; we expect Winsock 2.
 	 */
 	wVersionRequested = MAKEWORD(2, 2);
 	err = WSAStartup(wVersionRequested, &wsaData);
 	if (err != 0) {
 		strlcpy(errbuf, "Attempting to initialize Winsock failed",
 		    errbuf_size);
 		return (-1);
 	}
 #endif /* _WIN32 */

 #ifdef USE_LIBSMI
 	/*
 	 * XXX - should we just fail if this fails?  Some of the
 	 * libsmi calls may fail.
 	 */
 	smiInit("tcpdump");
 #endif

 	/*
 	 * Clears the error buffer, and uses it so we don't get
 	 * "unused argument" warnings at compile time.
 	 */
 	strlcpy(errbuf, "", errbuf_size);
 	return (0);
 }

 /*
  * Clean up anything that ndo_init() did.
  */
 void
 nd_cleanup(void)
 {
 #ifdef USE_LIBSMI
 	/*
 	 * This appears, in libsmi 0.4.8, to do nothing if smiInit()
 	 * wasn't done or failed, so we call it unconditionally.
 	 */
 	smiExit();
 #endif

 #ifdef _WIN32
 	/*
 	 * Undo the WSAStartup() call above.
 	 */
 	WSACleanup();
 #endif
 }

 int
 nd_have_smi_support(void)
 {
 #ifdef USE_LIBSMI
 	return (1);
 #else
 	return (0);
 #endif
 }

 /*
  * Indicates whether an SMI module has been loaded, so that we can use
  * libsmi to translate OIDs.
  */
 int nd_smi_module_loaded;

 int
 nd_load_smi_module(const char *module, char *errbuf, size_t errbuf_size)
 {
 #ifdef USE_LIBSMI
 	if (smiLoadModule(module) == 0) {
 		snprintf(errbuf, errbuf_size, "could not load MIB module %s",
 		    module);
 		return (-1);
 	}
 	nd_smi_module_loaded = 1;
 	return (0);
 #else
 	snprintf(errbuf, errbuf_size, "MIB module %s not loaded: no libsmi support",
 	    module);
 	return (-1);
 #endif
 }

 const char *
 nd_smi_version_string(void)
 {
 #ifdef USE_LIBSMI
 	return (smi_version_string);
 #else
 	return (NULL);
 #endif
 }


 int
 nd_push_buffer(netdissect_options *ndo, u_char *new_buffer,
 	       const u_char *new_packetp, const u_int newlen)
 {
 	struct netdissect_saved_packet_info *ndspi;

 	ndspi = (struct netdissect_saved_packet_info *)malloc(sizeof(struct netdissect_saved_packet_info));
 	if (ndspi == NULL)
 		return (0);	/* fail */
 	ndspi->ndspi_buffer = new_buffer;
 	ndspi->ndspi_packetp = ndo->ndo_packetp;
 	ndspi->ndspi_snapend = ndo->ndo_snapend;
 	ndspi->ndspi_prev = ndo->ndo_packet_info_stack;

 	ndo->ndo_packetp = new_packetp;
 	ndo->ndo_snapend = new_packetp + newlen;
 	ndo->ndo_packet_info_stack = ndspi;

 	return (1);	/* success */
 }


 /*
  * In a given netdissect_options structure:
  *
  *    push the current packet information onto the packet information
  *    stack;
  *
  *    given a pointer into the packet and a length past that point in
  *    the packet, calculate a new snapshot end that's at the lower
  *    of the current snapshot end and that point in the packet;
  *
  *    set the snapshot end to that new value.
  */
 int
 nd_push_snaplen(netdissect_options *ndo, const u_char *bp, const u_int newlen)
 {
 	struct netdissect_saved_packet_info *ndspi;
 	u_int snaplen_remaining;

 	ndspi = (struct netdissect_saved_packet_info *)malloc(sizeof(struct netdissect_saved_packet_info));
 	if (ndspi == NULL)
 		return (0);	/* fail */
 	ndspi->ndspi_buffer = NULL;	/* no new buffer */
 	ndspi->ndspi_packetp = ndo->ndo_packetp;
 	ndspi->ndspi_snapend = ndo->ndo_snapend;
 	ndspi->ndspi_prev = ndo->ndo_packet_info_stack;

 	/*
 	 * Push the saved previous data onto the stack.
 	 */
 	ndo->ndo_packet_info_stack = ndspi;

 	/*
 	 * Find out how many bytes remain after the current snapend.
 	 *
 	 * We're restricted to packets with at most UINT_MAX bytes;
 	 * cast the result to u_int, so that we don't get truncation
 	 * warnings on LP64 and LLP64 platforms.  (ptrdiff_t is
 	 * signed and we want an unsigned difference; the pointer
 	 * should at most be equal to snapend, and must *never*
 	 * be past snapend.)
 	 */
 	snaplen_remaining = (u_int)(ndo->ndo_snapend - bp);

 	/*
 	 * If the new snapend is smaller than the one calculated
 	 * above, set the snapend to that value, otherwise leave
 	 * it unchanged.
 	 */
 	if (newlen <= snaplen_remaining) {
 		/* Snapend isn't past the previous snapend */
 		ndo->ndo_snapend = bp + newlen;
 	}

 	return (1);	/* success */
 }

 /*
  * In a given netdissect_options structure:
  *
  *    given a pointer into the packet and a length past that point in
  *    the packet, calculate a new snapshot end that's at the lower
  *    of the previous snapshot end - or, if there is no previous
  *    snapshot end, the current snapshot end - and that point in the
  *    packet;
  *
  *    set the snapshot end to that new value.
  *
  * This is to change the current snapshot end.  This may increase the
  * snapshot end, as it may be used, for example, for a Jumbo Payload
  * option in IPv6.  It must not increase it past the snapshot length
  * atop which the current one was pushed, however.
  */
 void
 nd_change_snaplen(netdissect_options *ndo, const u_char *bp, const u_int newlen)
 {
 	struct netdissect_saved_packet_info *ndspi;
 	const u_char *previous_snapend;
 	u_int snaplen_remaining;

 	ndspi = ndo->ndo_packet_info_stack;
 	if (ndspi->ndspi_prev != NULL)
 		previous_snapend = ndspi->ndspi_prev->ndspi_snapend;
 	else
 		previous_snapend = ndo->ndo_snapend;

 	/*
 	 * Find out how many bytes remain after the previous
 	 * snapend - or, if there is no previous snapend, after
 	 * the current snapend.
 	 *
 	 * We're restricted to packets with at most UINT_MAX bytes;
 	 * cast the result to u_int, so that we don't get truncation
 	 * warnings on LP64 and LLP64 platforms.  (ptrdiff_t is
 	 * signed and we want an unsigned difference; the pointer
 	 * should at most be equal to snapend, and must *never*
 	 * be past snapend.)
 	 */
 	snaplen_remaining = (u_int)(previous_snapend - bp);

 	/*
 	 * If the new snapend is smaller than the one calculated
 	 * above, set the snapend to that value, otherwise leave
 	 * it unchanged.
 	 */
 	if (newlen <= snaplen_remaining) {
 		/* Snapend isn't past the previous snapend */
 		ndo->ndo_snapend = bp + newlen;
 	}
 }

 void
 nd_pop_packet_info(netdissect_options *ndo)
 {
 	struct netdissect_saved_packet_info *ndspi;

 	ndspi = ndo->ndo_packet_info_stack;
 	ndo->ndo_packetp = ndspi->ndspi_packetp;
 	ndo->ndo_snapend = ndspi->ndspi_snapend;
 	ndo->ndo_packet_info_stack = ndspi->ndspi_prev;

 	free(ndspi->ndspi_buffer);
 	free(ndspi);
 }

 void
 nd_pop_all_packet_info(netdissect_options *ndo)
 {
 	while (ndo->ndo_packet_info_stack != NULL)
 		nd_pop_packet_info(ndo);
 }
	/*
	* Copyright (c) 1988-1997
	* The Regents of the University of California. All rights reserved.
	*
	* Copyright (c) 1998-2012 Michael Richardson <[email protected]>
	* The TCPDUMP project
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that: (1) source code distributions
	* retain the above copyright notice and this paragraph in its entirety, (2)
	* distributions including binary code include the above copyright notice and
	* this paragraph in its entirety in the documentation or other materials
	* provided with the distribution, and (3) all advertising materials mentioning
	* features or use of this software display the following acknowledgement:
	* ``This product includes software developed by the University of California,
	* Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
	* the University 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 ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
	* WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
	* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
	*/

	#ifdef HAVE_CONFIG_H
	#include <config.h>
	#endif

	#include "netdissect-stdinc.h"
	#include "netdissect.h"
	#include <string.h>
	#include <stdio.h>
	#include <stdlib.h>

	#ifdef USE_LIBSMI
	#include <smi.h>
	#endif

	/*
	* Initialize anything that must be initialized before dissecting
	* packets.
	*
	* This should be called at the beginning of the program; it does
	* not need to be called, and should not be called, for every
	* netdissect_options structure.
	*/
	int
	nd_init(char *errbuf, size_t errbuf_size)
	{
	#ifdef _WIN32
	WORD wVersionRequested;
	WSADATA wsaData;
	int err;

	/*
	* Request Winsock 2.2; we expect Winsock 2.
	*/
	wVersionRequested = MAKEWORD(2, 2);
	err = WSAStartup(wVersionRequested, &wsaData);
	if (err != 0) {
	strlcpy(errbuf, "Attempting to initialize Winsock failed",
	errbuf_size);
	return (-1);
	}
	#endif /* _WIN32 */

	#ifdef USE_LIBSMI
	/*
	* XXX - should we just fail if this fails? Some of the
	* libsmi calls may fail.
	*/
	smiInit("tcpdump");
	#endif

	/*
	* Clears the error buffer, and uses it so we don't get
	* "unused argument" warnings at compile time.
	*/
	strlcpy(errbuf, "", errbuf_size);
	return (0);
	}

	/*
	* Clean up anything that ndo_init() did.
	*/
	void
	nd_cleanup(void)
	{
	#ifdef USE_LIBSMI
	/*
	* This appears, in libsmi 0.4.8, to do nothing if smiInit()
	* wasn't done or failed, so we call it unconditionally.
	*/
	smiExit();
	#endif

	#ifdef _WIN32
	/*
	* Undo the WSAStartup() call above.
	*/
	WSACleanup();
	#endif
	}

	int
	nd_have_smi_support(void)
	{
	#ifdef USE_LIBSMI
	return (1);
	#else
	return (0);
	#endif
	}

	/*
	* Indicates whether an SMI module has been loaded, so that we can use
	* libsmi to translate OIDs.
	*/
	int nd_smi_module_loaded;

	int
	nd_load_smi_module(const char module, char errbuf, size_t errbuf_size)
	{
	#ifdef USE_LIBSMI
	if (smiLoadModule(module) == 0) {
	snprintf(errbuf, errbuf_size, "could not load MIB module %s",
	module);
	return (-1);
	}
	nd_smi_module_loaded = 1;
	return (0);
	#else
	snprintf(errbuf, errbuf_size, "MIB module %s not loaded: no libsmi support",
	module);
	return (-1);
	#endif
	}

	const char *
	nd_smi_version_string(void)
	{
	#ifdef USE_LIBSMI
	return (smi_version_string);
	#else
	return (NULL);
	#endif
	}


	int
	nd_push_buffer(netdissect_options ndo, u_char new_buffer,
	const u_char *new_packetp, const u_int newlen)
	{
	struct netdissect_saved_packet_info *ndspi;

	ndspi = (struct netdissect_saved_packet_info *)malloc(sizeof(struct netdissect_saved_packet_info));
	if (ndspi == NULL)
	return (0); /* fail */
	ndspi->ndspi_buffer = new_buffer;
	ndspi->ndspi_packetp = ndo->ndo_packetp;
	ndspi->ndspi_snapend = ndo->ndo_snapend;
	ndspi->ndspi_prev = ndo->ndo_packet_info_stack;

	ndo->ndo_packetp = new_packetp;
	ndo->ndo_snapend = new_packetp + newlen;
	ndo->ndo_packet_info_stack = ndspi;

	return (1); /* success */
	}


	/*
	* In a given netdissect_options structure:
	*
	* push the current packet information onto the packet information
	* stack;
	*
	* given a pointer into the packet and a length past that point in
	* the packet, calculate a new snapshot end that's at the lower
	* of the current snapshot end and that point in the packet;
	*
	* set the snapshot end to that new value.
	*/
	int
	nd_push_snaplen(netdissect_options ndo, const u_char bp, const u_int newlen)
	{
	struct netdissect_saved_packet_info *ndspi;
	u_int snaplen_remaining;

	ndspi = (struct netdissect_saved_packet_info *)malloc(sizeof(struct netdissect_saved_packet_info));
	if (ndspi == NULL)
	return (0); /* fail */
	ndspi->ndspi_buffer = NULL; /* no new buffer */
	ndspi->ndspi_packetp = ndo->ndo_packetp;
	ndspi->ndspi_snapend = ndo->ndo_snapend;
	ndspi->ndspi_prev = ndo->ndo_packet_info_stack;

	/*
	* Push the saved previous data onto the stack.
	*/
	ndo->ndo_packet_info_stack = ndspi;

	/*
	* Find out how many bytes remain after the current snapend.
	*
	* We're restricted to packets with at most UINT_MAX bytes;
	* cast the result to u_int, so that we don't get truncation
	* warnings on LP64 and LLP64 platforms. (ptrdiff_t is
	* signed and we want an unsigned difference; the pointer
	* should at most be equal to snapend, and must never
	* be past snapend.)
	*/
	snaplen_remaining = (u_int)(ndo->ndo_snapend - bp);

	/*
	* If the new snapend is smaller than the one calculated
	* above, set the snapend to that value, otherwise leave
	* it unchanged.
	*/
	if (newlen <= snaplen_remaining) {
	/* Snapend isn't past the previous snapend */
	ndo->ndo_snapend = bp + newlen;
	}

	return (1); /* success */
	}

	/*
	* In a given netdissect_options structure:
	*
	* given a pointer into the packet and a length past that point in
	* the packet, calculate a new snapshot end that's at the lower
	* of the previous snapshot end - or, if there is no previous
	* snapshot end, the current snapshot end - and that point in the
	* packet;
	*
	* set the snapshot end to that new value.
	*
	* This is to change the current snapshot end. This may increase the
	* snapshot end, as it may be used, for example, for a Jumbo Payload
	* option in IPv6. It must not increase it past the snapshot length
	* atop which the current one was pushed, however.
	*/
	void
	nd_change_snaplen(netdissect_options ndo, const u_char bp, const u_int newlen)
	{
	struct netdissect_saved_packet_info *ndspi;
	const u_char *previous_snapend;
	u_int snaplen_remaining;

	ndspi = ndo->ndo_packet_info_stack;
	if (ndspi->ndspi_prev != NULL)
	previous_snapend = ndspi->ndspi_prev->ndspi_snapend;
	else
	previous_snapend = ndo->ndo_snapend;

	/*
	* Find out how many bytes remain after the previous
	* snapend - or, if there is no previous snapend, after
	* the current snapend.
	*
	* We're restricted to packets with at most UINT_MAX bytes;
	* cast the result to u_int, so that we don't get truncation
	* warnings on LP64 and LLP64 platforms. (ptrdiff_t is
	* signed and we want an unsigned difference; the pointer
	* should at most be equal to snapend, and must never
	* be past snapend.)
	*/
	snaplen_remaining = (u_int)(previous_snapend - bp);

	/*
	* If the new snapend is smaller than the one calculated
	* above, set the snapend to that value, otherwise leave
	* it unchanged.
	*/
	if (newlen <= snaplen_remaining) {
	/* Snapend isn't past the previous snapend */
	ndo->ndo_snapend = bp + newlen;
	}
	}

	void
	nd_pop_packet_info(netdissect_options *ndo)
	{
	struct netdissect_saved_packet_info *ndspi;

	ndspi = ndo->ndo_packet_info_stack;
	ndo->ndo_packetp = ndspi->ndspi_packetp;
	ndo->ndo_snapend = ndspi->ndspi_snapend;
	ndo->ndo_packet_info_stack = ndspi->ndspi_prev;

	free(ndspi->ndspi_buffer);
	free(ndspi);
	}

	void
	nd_pop_all_packet_info(netdissect_options *ndo)
	{
	while (ndo->ndo_packet_info_stack != NULL)
	nd_pop_packet_info(ndo);
	}