savefile.c

用来监视网络通信数据的源代码和应用程序,方便网络程序底层开发.

/*
 * Copyright (c) 1993, 1994, 1995, 1996, 1997
 *	The Regents of the University of California.  All rights reserved.
 *
 * 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.
 *
 * savefile.c - supports offline use of tcpdump
 *	Extraction/creation by Jeffrey Mogul, DECWRL
 *	Modified by Steve McCanne, LBL.
 *
 * Used to save the received packet headers, after filtering, to
 * a file, and then read them later.
 * The first record in the file contains saved values for the machine
 * dependent values so we can print the dump file on any architecture.
 */

#ifndef lint
static const char rcsid[] =
    "@(#) $Header: /tcpdump/master/libpcap/savefile.c,v 1.75 2003/01/23 07:24:53 guy Exp $ (LBL)";
#endif

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <errno.h>
#include <memory.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "pcap-int.h"

#ifdef HAVE_OS_PROTO_H
#include "os-proto.h"
#endif

#define TCPDUMP_MAGIC 0xa1b2c3d4
#define PATCHED_TCPDUMP_MAGIC 0xa1b2cd34

/*
 * We use the "receiver-makes-right" approach to byte order,
 * because time is at a premium when we are writing the file.
 * In other words, the pcap_file_header and pcap_pkthdr,
 * records are written in host byte order.
 * Note that the packets are always written in network byte order.
 *
 * ntoh[ls] aren't sufficient because we might need to swap on a big-endian
 * machine (if the file was written in little-end order).
 */
#define	SWAPLONG(y) \
((((y)&0xff)<<24) | (((y)&0xff00)<<8) | (((y)&0xff0000)>>8) | (((y)>>24)&0xff))
#define	SWAPSHORT(y) \
	( (((y)&0xff)<<8) | ((u_short)((y)&0xff00)>>8) )

#define SFERR_TRUNC		1
#define SFERR_BADVERSION	2
#define SFERR_BADF		3
#define SFERR_EOF		4 /* not really an error, just a status */

/*
 * We don't write DLT_* values to the capture file header, because
 * they're not the same on all platforms.
 *
 * Unfortunately, the various flavors of BSD have not always used the same
 * numerical values for the same data types, and various patches to
 * libpcap for non-BSD OSes have added their own DLT_* codes for link
 * layer encapsulation types seen on those OSes, and those codes have had,
 * in some cases, values that were also used, on other platforms, for other
 * link layer encapsulation types.
 *
 * This means that capture files of a type whose numerical DLT_* code
 * means different things on different BSDs, or with different versions
 * of libpcap, can't always be read on systems other than those like
 * the one running on the machine on which the capture was made.
 *
 * Instead, we define here a set of LINKTYPE_* codes, and map DLT_* codes
 * to LINKTYPE_* codes when writing a savefile header, and map LINKTYPE_*
 * codes to DLT_* codes when reading a savefile header.
 *
 * For those DLT_* codes that have, as far as we know, the same values on
 * all platforms (DLT_NULL through DLT_FDDI), we define LINKTYPE_xxx as
 * DLT_xxx; that way, captures of those types can still be read by
 * versions of libpcap that map LINKTYPE_* values to DLT_* values, and
 * captures of those types written by versions of libpcap that map DLT_
 * values to LINKTYPE_ values can still be read by older versions
 * of libpcap.
 *
 * The other LINKTYPE_* codes are given values starting at 100, in the
 * hopes that no DLT_* code will be given one of those values.
 *
 * In order to ensure that a given LINKTYPE_* code's value will refer to
 * the same encapsulation type on all platforms, you should not allocate
 * a new LINKTYPE_* value without consulting "[e-mail]".
 * The tcpdump developers will allocate a value for you, and will not
 * subsequently allocate it to anybody else; that value will be added to
 * the "pcap.h" in the tcpdump.org CVS repository, so that a future
 * libpcap release will include it.
 *
 * You should, if possible, also contribute patches to libpcap and tcpdump
 * to handle the new encapsulation type, so that they can also be checked
 * into the tcpdump.org CVS repository and so that they will appear in
 * future libpcap and tcpdump releases.
 */
#define LINKTYPE_NULL		DLT_NULL
#define LINKTYPE_ETHERNET	DLT_EN10MB	/* also for 100Mb and up */
#define LINKTYPE_EXP_ETHERNET	DLT_EN3MB	/* 3Mb experimental Ethernet */
#define LINKTYPE_AX25		DLT_AX25
#define LINKTYPE_PRONET		DLT_PRONET
#define LINKTYPE_CHAOS		DLT_CHAOS
#define LINKTYPE_TOKEN_RING	DLT_IEEE802	/* DLT_IEEE802 is used for Token Ring */
#define LINKTYPE_ARCNET		DLT_ARCNET	/* BSD-style headers */
#define LINKTYPE_SLIP		DLT_SLIP
#define LINKTYPE_PPP		DLT_PPP
#define LINKTYPE_FDDI		DLT_FDDI

/*
 * LINKTYPE_PPP is for use when there might, or might not, be an RFC 1662
 * PPP in HDLC-like framing header (with 0xff 0x03 before the PPP protocol
 * field) at the beginning of the packet.
 *
 * This is for use when there is always such a header; the address field
 * might be 0xff, for regular PPP, or it might be an address field for Cisco
 * point-to-point with HDLC framing as per section 4.3.1 of RFC 1547 ("Cisco
 * HDLC").  This is, for example, what you get with NetBSD's DLT_PPP_SERIAL.
 *
 * We give it the same value as NetBSD's DLT_PPP_SERIAL, in the hopes that
 * nobody else will choose a DLT_ value of 50, and so that DLT_PPP_SERIAL
 * captures will be written out with a link type that NetBSD's tcpdump
 * can read.
 */
#define LINKTYPE_PPP_HDLC	50		/* PPP in HDLC-like framing */

#define LINKTYPE_PPP_ETHER	51		/* NetBSD PPP-over-Ethernet */

#define LINKTYPE_ATM_RFC1483	100		/* LLC/SNAP-encapsulated ATM */
#define LINKTYPE_RAW		101		/* raw IP */
#define LINKTYPE_SLIP_BSDOS	102		/* BSD/OS SLIP BPF header */
#define LINKTYPE_PPP_BSDOS	103		/* BSD/OS PPP BPF header */
#define LINKTYPE_C_HDLC		104		/* Cisco HDLC */
#define LINKTYPE_IEEE802_11	105		/* IEEE 802.11 (wireless) */
#define LINKTYPE_ATM_CLIP	106		/* Linux Classical IP over ATM */
#define LINKTYPE_FRELAY		107		/* Frame Relay */
#define LINKTYPE_LOOP		108		/* OpenBSD loopback */

#define LINKTYPE_LINUX_SLL	113		/* Linux cooked socket capture */
#define LINKTYPE_LTALK		114		/* Apple LocalTalk hardware */
#define LINKTYPE_ECONET		115		/* Acorn Econet */

#define LINKTYPE_CISCO_IOS	118		/* For Cisco-internal use */
#define LINKTYPE_PRISM_HEADER	119		/* 802.11+Prism II monitor mode */
#define LINKTYPE_AIRONET_HEADER	120		/* FreeBSD Aironet driver stuff */
#define LINKTYPE_IP_OVER_FC	122		/* RFC 2625 IP-over-Fibre Channel */
#define LINKTYPE_SUNATM		123		/* Solaris+SunATM */

#define LINKTYPE_IEEE802_11_RADIO 127		/* 802.11 plus WLAN header */

#define LINKTYPE_TZSP		128		/* Tazmen Sniffer Protocol */

#define LINKTYPE_ARCNET_LINUX	129		/* Linux-style headers */

/*
 * These types are reserved for future use.
 */
#define LINKTYPE_ENC		109		/* OpenBSD IPSEC enc */
#define LINKTYPE_LANE8023	110		/* ATM LANE + 802.3 */
#define LINKTYPE_HIPPI		111		/* NetBSD HIPPI */
#define LINKTYPE_HDLC		112		/* NetBSD HDLC framing */
#define LINKTYPE_IPFILTER	116		/* IP Filter capture files */
#define LINKTYPE_PFLOG		117		/* OpenBSD DLT_PFLOG */
#define LINKTYPE_HHDLC		121		/* Siemens HiPath HDLC */
#define LINKTYPE_RIO		124		/* RapidIO */
#define LINKTYPE_PCI_EXP	125		/* PCI Express */
#define LINKTYPE_AURORA		126		/* Xilinx Aurora link layer */

static struct linktype_map {
	int	dlt;
	int	linktype;
} map[] = {
	/*
	 * These DLT_* codes have LINKTYPE_* codes with values identical
	 * to the values of the corresponding DLT_* code.
	 */
	{ DLT_NULL,		LINKTYPE_NULL },
	{ DLT_EN10MB,		LINKTYPE_ETHERNET },
	{ DLT_EN3MB,		LINKTYPE_EXP_ETHERNET },
	{ DLT_AX25,		LINKTYPE_AX25 },
	{ DLT_PRONET,		LINKTYPE_PRONET },
	{ DLT_CHAOS,		LINKTYPE_CHAOS },
	{ DLT_IEEE802,		LINKTYPE_TOKEN_RING },
	{ DLT_ARCNET,		LINKTYPE_ARCNET },
	{ DLT_SLIP,		LINKTYPE_SLIP },
	{ DLT_PPP,		LINKTYPE_PPP },
	{ DLT_FDDI,	 	LINKTYPE_FDDI },

	/*
	 * These DLT_* codes have different values on different
	 * platforms; we map them to LINKTYPE_* codes that
	 * have values that should never be equal to any DLT_*
	 * code.
	 */
#ifdef DLT_FR
	/* BSD/OS Frame Relay */
	{ DLT_FR,		LINKTYPE_FRELAY },
#endif
	{ DLT_ATM_RFC1483, 	LINKTYPE_ATM_RFC1483 },
	{ DLT_RAW,		LINKTYPE_RAW },
	{ DLT_SLIP_BSDOS,	LINKTYPE_SLIP_BSDOS },
	{ DLT_PPP_BSDOS,	LINKTYPE_PPP_BSDOS },

	/* BSD/OS Cisco HDLC */
	{ DLT_C_HDLC,		LINKTYPE_C_HDLC },

	/*
	 * These DLT_* codes are not on all platforms, but, so far,
	 * there don't appear to be any platforms that define
	 * other codes with those values; we map them to
	 * different LINKTYPE_* values anyway, just in case.
	 */

	/* Linux ATM Classical IP */
	{ DLT_ATM_CLIP,		LINKTYPE_ATM_CLIP },

	/* NetBSD sync/async serial PPP (or Cisco HDLC) */
	{ DLT_PPP_SERIAL,	LINKTYPE_PPP_HDLC },

	/* NetBSD PPP over Ethernet */
	{ DLT_PPP_ETHER,	LINKTYPE_PPP_ETHER },

	/* IEEE 802.11 wireless */
	{ DLT_IEEE802_11,	LINKTYPE_IEEE802_11 },

	/* Frame Relay */
	{ DLT_FRELAY,		LINKTYPE_FRELAY },

	/* OpenBSD loopback */
	{ DLT_LOOP,		LINKTYPE_LOOP },

	/* Linux cooked socket capture */
	{ DLT_LINUX_SLL,	LINKTYPE_LINUX_SLL },

	/* Apple LocalTalk hardware */
	{ DLT_LTALK,		LINKTYPE_LTALK },

	/* Acorn Econet */
	{ DLT_ECONET,		LINKTYPE_ECONET },

	/* For Cisco-internal use */
	{ DLT_CISCO_IOS,	LINKTYPE_CISCO_IOS },

	/* Prism II monitor-mode header plus 802.11 header */
	{ DLT_PRISM_HEADER,	LINKTYPE_PRISM_HEADER },

	/* FreeBSD Aironet driver stuff */
	{ DLT_AIRONET_HEADER,	LINKTYPE_AIRONET_HEADER },

	/* Siemens HiPath HDLC */
	{ DLT_HHDLC,		LINKTYPE_HHDLC },

	/* RFC 2625 IP-over-Fibre Channel */
	{ DLT_IP_OVER_FC,	LINKTYPE_IP_OVER_FC },

	/* Solaris+SunATM */
	{ DLT_SUNATM,		LINKTYPE_SUNATM },

	/* RapidIO */
	{ DLT_RIO,		LINKTYPE_RIO },

	/* PCI Express */
	{ DLT_PCI_EXP,		LINKTYPE_PCI_EXP },

	/* Xilinx Aurora link layer */
	{ DLT_AURORA,		LINKTYPE_AURORA },

	/* 802.11 plus WLAN header */
	{ DLT_IEEE802_11_RADIO,	LINKTYPE_IEEE802_11_RADIO },

	/* Tazmen Sniffer Protocol */
	{ DLT_TZSP,		LINKTYPE_TZSP },

	/* Arcnet with Linux-style link-layer headers */
	{ DLT_ARCNET_LINUX,	LINKTYPE_ARCNET_LINUX },

	/*
	 * Any platform that defines additional DLT_* codes should:
	 *
	 *	request a LINKTYPE_* code and value from tcpdump.org,
	 *	as per the above;
	 *
	 *	add, in their version of libpcap, an entry to map
	 *	those DLT_* codes to the corresponding LINKTYPE_*
	 *	code;
	 *
	 *	redefine, in their "net/bpf.h", any DLT_* values
	 *	that collide with the values used by their additional
	 *	DLT_* codes, to remove those collisions (but without
	 *	making them collide with any of the LINKTYPE_*
	 *	values equal to 50 or above; they should also avoid
	 *	defining DLT_* values that collide with those
	 *	LINKTYPE_* values, either).
	 */
	{ -1,			-1 }
};

static int
dlt_to_linktype(int dlt)
{
	int i;

	for (i = 0; map[i].dlt != -1; i++) {
		if (map[i].dlt == dlt)
			return (map[i].linktype);
	}

	/*
	 * If we don't have a mapping for this DLT_ code, return an
	 * error; that means that the table above needs to have an
	 * entry added.
	 */
	return (-1);
}

static int
linktype_to_dlt(int linktype)
{
	int i;

	for (i = 0; map[i].linktype != -1; i++) {
		if (map[i].linktype == linktype)
			return (map[i].dlt);
	}

	/*
	 * If we don't have an entry for this link type, return
	 * the link type value; it may be a DLT_ value from an
	 * older version of libpcap.
	 */
	return linktype;
}

static int
sf_write_header(FILE *fp, int linktype, int thiszone, int snaplen)
{
	struct pcap_file_header hdr;

	hdr.magic = TCPDUMP_MAGIC;
	hdr.version_major = PCAP_VERSION_MAJOR;
	hdr.version_minor = PCAP_VERSION_MINOR;