savefile.c

Windows XP下的抓包程序实现

 * Controller Area Network (CAN) v. 2.0B packets.
 * DLT_ requested by Gianluca Varenni <[e-mail]>.
 * Used to dump CAN packets coming from a CAN Vector board.
 * More documentation on the CAN v2.0B frames can be found at
 * http://www.can-cia.org/downloads/?269
 */
#define LINKTYPE_CAN20B         190

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_SYMANTEC_FIREWALL, LINKTYPE_SYMANTEC_FIREWALL },
	{ 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 },

	/* OpenBSD DLT_PFLOG */
	{ DLT_PFLOG,		LINKTYPE_PFLOG },

	/* 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 BSD radio 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 },

        /* Juniper-internal chassis encapsulation */
        { DLT_JUNIPER_MLPPP,    LINKTYPE_JUNIPER_MLPPP },
        { DLT_JUNIPER_MLFR,     LINKTYPE_JUNIPER_MLFR },
        { DLT_JUNIPER_ES,       LINKTYPE_JUNIPER_ES },
        { DLT_JUNIPER_GGSN,     LINKTYPE_JUNIPER_GGSN },
        { DLT_JUNIPER_MFR,      LINKTYPE_JUNIPER_MFR },
        { DLT_JUNIPER_ATM2,     LINKTYPE_JUNIPER_ATM2 },
        { DLT_JUNIPER_SERVICES, LINKTYPE_JUNIPER_SERVICES },
        { DLT_JUNIPER_ATM1,     LINKTYPE_JUNIPER_ATM1 },

	/* Apple IP-over-IEEE 1394 cooked header */
	{ DLT_APPLE_IP_OVER_IEEE1394, LINKTYPE_APPLE_IP_OVER_IEEE1394 },

	/* SS7 */
	{ DLT_MTP2_WITH_PHDR,	LINKTYPE_MTP2_WITH_PHDR },
	{ DLT_MTP2,		LINKTYPE_MTP2 },
	{ DLT_MTP3,		LINKTYPE_MTP3 },
	{ DLT_SCCP,		LINKTYPE_SCCP },

	/* DOCSIS MAC frames */
	{ DLT_DOCSIS,		LINKTYPE_DOCSIS },

	/* IrDA IrLAP packets + Linux-cooked header */
	{ DLT_LINUX_IRDA,	LINKTYPE_LINUX_IRDA },

	/* IBM SP and Next Federation switches */
	{ DLT_IBM_SP,		LINKTYPE_IBM_SP },
	{ DLT_IBM_SN,		LINKTYPE_IBM_SN },

	/* 802.11 plus AVS radio header */
	{ DLT_IEEE802_11_RADIO_AVS, LINKTYPE_IEEE802_11_RADIO_AVS },

	/*
	 * 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).
	 */

	/* Juniper-internal chassis encapsulation */
	{ DLT_JUNIPER_MONITOR,	LINKTYPE_JUNIPER_MONITOR },

	/* BACnet MS/TP */
	{ DLT_BACNET_MS_TP,	LINKTYPE_BACNET_MS_TP },

	/* PPP for pppd, with direction flag in the PPP header */
	{ DLT_PPP_PPPD,		LINKTYPE_PPP_PPPD},

	/* Juniper-internal chassis encapsulation */
        { DLT_JUNIPER_PPPOE,    LINKTYPE_JUNIPER_PPPOE },
        { DLT_JUNIPER_PPPOE_ATM,LINKTYPE_JUNIPER_PPPOE_ATM },

	/* GPRS LLC */
	{ DLT_GPRS_LLC,		LINKTYPE_GPRS_LLC },

	/* Transparent Generic Framing Procedure (ITU-T G.7041/Y.1303) */
	{ DLT_GPF_T,		LINKTYPE_GPF_T },

	/* Framed Generic Framing Procedure (ITU-T G.7041/Y.1303) */
	{ DLT_GPF_F,		LINKTYPE_GPF_F },

	{ DLT_GCOM_T1E1,	LINKTYPE_GCOM_T1E1 },
	{ DLT_GCOM_SERIAL,	LINKTYPE_GCOM_SERIAL },

        /* Juniper-internal chassis encapsulation */
        { DLT_JUNIPER_PIC_PEER, LINKTYPE_JUNIPER_PIC_PEER },

	/* Endace types */
	{ DLT_ERF_ETH,		LINKTYPE_ERF_ETH },
	{ DLT_ERF_POS,		LINKTYPE_ERF_POS },

	/* viSDN LAPD */
	{ DLT_LINUX_LAPD,	LINKTYPE_LINUX_LAPD },

        /* Juniper meta-information before Ether, PPP, Frame Relay, C-HDLC Frames */
        { DLT_JUNIPER_ETHER, LINKTYPE_JUNIPER_ETHER },
        { DLT_JUNIPER_PPP, LINKTYPE_JUNIPER_PPP },
        { DLT_JUNIPER_FRELAY, LINKTYPE_JUNIPER_FRELAY },
        { DLT_JUNIPER_CHDLC, LINKTYPE_JUNIPER_CHDLC },

        /* Multi Link Frame Relay (FRF.16) */
        { DLT_MFR,              LINKTYPE_MFR },

        /* Juniper Voice PIC */
        { DLT_JUNIPER_VP,       LINKTYPE_JUNIPER_VP },

		/* Controller Area Network (CAN) v2.0B */
		{ DLT_A429,				LINKTYPE_A429 },

		/* Controller Area Network (CAN) v2.0B */
		{ DLT_CAN20B,				LINKTYPE_CAN20B },

		/* Arinc 653 Interpartition Communication messages */
		{ DLT_A653_ICM,         LINKTYPE_A653_ICM },

	{ -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;

	hdr.thiszone = thiszone;
	hdr.snaplen = snaplen;
	hdr.sigfigs = 0;
	hdr.linktype = linktype;

	if (fwrite((char *)&hdr, sizeof(hdr), 1, fp) != 1)
		return (-1);

	return (0);
}

static void
swap_hdr(struct pcap_file_header *hp)
{
	hp->version_major = SWAPSHORT(hp->version_major);
	hp->version_minor = SWAPSHORT(hp->version_minor);
	hp->thiszone = SWAPLONG(hp->thiszone);
	hp->sigfigs = SWAPLONG(hp->sigfigs);
	hp->snaplen = SWAPLONG(hp->snaplen);
	hp->linktype = SWAPLONG(hp->linktype);
}

static int
sf_getnonblock(pcap_t *p, char *errbuf)
{
	/*
	 * This is a savefile, not a live capture file, so never say
	 * it's in non-blocking mode.
	 */
	return (0);
}

static int
sf_setnonblock(pcap_t *p, int nonblock, char *errbuf)
{
	/*
	 * This is a savefile, not a live capture file, so ignore
	 * requests to put it in non-blocking mode.
	 */
	return (0);
}

static int
sf_stats(pcap_t *p, struct pcap_stat *ps)
{
	snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
	    "Statistics aren't available from savefiles");
	return (-1);
}

static int
sf_inject(pcap_t *p, const void *buf _U_, size_t size _U_)
{
	strlcpy(p->errbuf, "Sending packets isn't supported on savefiles",
	    PCAP_ERRBUF_SIZE);
	return (-1);
}

/*
 * Set direction flag: Which packets do we accept on a forwarding
 * single device? IN, OUT or both?
 */
static int
sf_setdirection(pcap_t *p, pcap_direction_t d)
{
	snprintf(p->errbuf, sizeof(p->errbuf),
	    "Setting direction is not supported on savefiles");
	return (-1);
}

static void
sf_close(pcap_t *p)
{
	if (p->sf.rfile != stdin)
		(void)fclose(p->sf.rfile);
	if (p->sf.base != NULL)
		free(p->sf.base);
}

pcap_t *
pcap_open_offline(const char *fname, char *errbuf)
{
	FILE *fp;
	pcap_t *p;

	if (fname[0] == '-' && fname[1] == '\0')
	{
		fp = stdin;
#if defined(WIN32) || defined(MSDOS)
		/*
		 * We're reading from the standard input, so put it in binary
		 * mode, as savefiles are binary files.
		 */
		SET_BINMODE(fp);
#endif
	}
	else {
#if !defined(WIN32) && !defined(MSDOS)
		fp = fopen(fname, "r");
#else
		fp = fopen(fname, "rb");
#endif
		if (fp == NULL) {
			snprintf(errbuf, PCAP_ERRBUF_SIZE, "%s: %s", fname,
			    pcap_strerror(errno));
			return (NULL);
		}
	}
	p = pcap_fopen_offline(fp, errbuf);
	if (p == NULL) {
		if (fp != stdin)
			fclose(fp);
	}
	return (p);
}

pcap_t *
pcap_fopen_offline(FILE *fp, char *errbuf)
{
	register pcap_t *p;
	struct pcap_file_header hdr;
	size_t amt_read;
	bpf_u_int32 magic;
	int linklen;

	p = (pcap_t *)malloc(sizeof(*p));
	if (p == NULL) {
		strlcpy(errbuf, "out of swap", PCAP_ERRBUF_SIZE);
		return (NULL);
	}

	memset((char *)p, 0, sizeof(*p));

	amt_read = fread((char *)&hdr, 1, sizeof(hdr), fp);
	if (amt_read != sizeof(hdr)) {
		if (ferror(fp)) {
			snprintf(errbuf, PCAP_ERRBUF_SIZE,
			    "error reading dump file: %s",
			    pcap_strerror(errno));
		} else {
			snprintf(errbuf, PCAP_ERRBUF_SIZE,
			    "truncated dump file; tried to read %lu file header bytes, only got %lu",
			    (unsigned long)sizeof(hdr),
			    (unsigned long)amt_read);
		}
		goto bad;
	}
	magic = hdr.magic;
	if (magic != TCPDUMP_MAGIC && magic != KUZNETZOV_TCPDUMP_MAGIC) {
		magic = SWAPLONG(magic);
		if (magic != TCPDUMP_MAGIC && magic != KUZNETZOV_TCPDUMP_MAGIC) {
			snprintf(errbuf, PCAP_ERRBUF_SIZE,
			    "bad dump file format");
			goto bad;
		}
		p->sf.swapped = 1;
		swap_hdr(&hdr);
	}
	if (magic == KUZNETZOV_TCPDUMP_MAGIC) {
		/*
		 * XXX - the patch that's in some versions of libpcap
		 * changes the packet header but not the magic number,
		 * and some other versions with this magic number have
		 * some extra debugging information in the packet header;
		 * we'd have to use some hacks^H^H^H^H^Hheuristics to
		 * detect those variants.
		 *
		 * Ethereal does that, but it does so by trying to read
		 * the first two packets of the file with each of the
		 * record header formats.  That currently means it seeks
		 * backwards and retries the reads, which doesn't work
		 * on pipes.  We want to be able to read from a pipe, so
		 * that strategy won't work; we'd have to buffer some
		 * data ourselves and read from that buffer in order to
		 * make that work.
		 */
		p->sf.hdrsize = sizeof(struct pcap_sf_patched_pkthdr);
	} else
		p->sf.hdrsize = sizeof(struct pcap_sf_pkthdr);
	if (hdr.version_major < PCAP_VERSION_MAJOR) {
		snprintf(errbuf, PCAP_ERRBUF_SIZE, "archaic file format");
		goto bad;
	}
	p->tzoff = hdr.thiszone;
	p->snapshot = hdr.snaplen;
	p->linktype = linktype_to_dlt(hdr.linktype);