pcap.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.

	(u_char)'\060', (u_char)'\061', (u_char)'\062', (u_char)'\063',
	(u_char)'\064', (u_char)'\065', (u_char)'\066', (u_char)'\067',
	(u_char)'\070', (u_char)'\071', (u_char)'\072', (u_char)'\073',
	(u_char)'\074', (u_char)'\075', (u_char)'\076', (u_char)'\077',
	(u_char)'\100', (u_char)'\141', (u_char)'\142', (u_char)'\143',
	(u_char)'\144', (u_char)'\145', (u_char)'\146', (u_char)'\147',
	(u_char)'\150', (u_char)'\151', (u_char)'\152', (u_char)'\153',
	(u_char)'\154', (u_char)'\155', (u_char)'\156', (u_char)'\157',
	(u_char)'\160', (u_char)'\161', (u_char)'\162', (u_char)'\163',
	(u_char)'\164', (u_char)'\165', (u_char)'\166', (u_char)'\167',
	(u_char)'\170', (u_char)'\171', (u_char)'\172', (u_char)'\133',
	(u_char)'\134', (u_char)'\135', (u_char)'\136', (u_char)'\137',
	(u_char)'\140', (u_char)'\141', (u_char)'\142', (u_char)'\143',
	(u_char)'\144', (u_char)'\145', (u_char)'\146', (u_char)'\147',
	(u_char)'\150', (u_char)'\151', (u_char)'\152', (u_char)'\153',
	(u_char)'\154', (u_char)'\155', (u_char)'\156', (u_char)'\157',
	(u_char)'\160', (u_char)'\161', (u_char)'\162', (u_char)'\163',
	(u_char)'\164', (u_char)'\165', (u_char)'\166', (u_char)'\167',
	(u_char)'\170', (u_char)'\171', (u_char)'\172', (u_char)'\173',
	(u_char)'\174', (u_char)'\175', (u_char)'\176', (u_char)'\177',
	(u_char)'\200', (u_char)'\201', (u_char)'\202', (u_char)'\203',
	(u_char)'\204', (u_char)'\205', (u_char)'\206', (u_char)'\207',
	(u_char)'\210', (u_char)'\211', (u_char)'\212', (u_char)'\213',
	(u_char)'\214', (u_char)'\215', (u_char)'\216', (u_char)'\217',
	(u_char)'\220', (u_char)'\221', (u_char)'\222', (u_char)'\223',
	(u_char)'\224', (u_char)'\225', (u_char)'\226', (u_char)'\227',
	(u_char)'\230', (u_char)'\231', (u_char)'\232', (u_char)'\233',
	(u_char)'\234', (u_char)'\235', (u_char)'\236', (u_char)'\237',
	(u_char)'\240', (u_char)'\241', (u_char)'\242', (u_char)'\243',
	(u_char)'\244', (u_char)'\245', (u_char)'\246', (u_char)'\247',
	(u_char)'\250', (u_char)'\251', (u_char)'\252', (u_char)'\253',
	(u_char)'\254', (u_char)'\255', (u_char)'\256', (u_char)'\257',
	(u_char)'\260', (u_char)'\261', (u_char)'\262', (u_char)'\263',
	(u_char)'\264', (u_char)'\265', (u_char)'\266', (u_char)'\267',
	(u_char)'\270', (u_char)'\271', (u_char)'\272', (u_char)'\273',
	(u_char)'\274', (u_char)'\275', (u_char)'\276', (u_char)'\277',
	(u_char)'\300', (u_char)'\341', (u_char)'\342', (u_char)'\343',
	(u_char)'\344', (u_char)'\345', (u_char)'\346', (u_char)'\347',
	(u_char)'\350', (u_char)'\351', (u_char)'\352', (u_char)'\353',
	(u_char)'\354', (u_char)'\355', (u_char)'\356', (u_char)'\357',
	(u_char)'\360', (u_char)'\361', (u_char)'\362', (u_char)'\363',
	(u_char)'\364', (u_char)'\365', (u_char)'\366', (u_char)'\367',
	(u_char)'\370', (u_char)'\371', (u_char)'\372', (u_char)'\333',
	(u_char)'\334', (u_char)'\335', (u_char)'\336', (u_char)'\337',
	(u_char)'\340', (u_char)'\341', (u_char)'\342', (u_char)'\343',
	(u_char)'\344', (u_char)'\345', (u_char)'\346', (u_char)'\347',
	(u_char)'\350', (u_char)'\351', (u_char)'\352', (u_char)'\353',
	(u_char)'\354', (u_char)'\355', (u_char)'\356', (u_char)'\357',
	(u_char)'\360', (u_char)'\361', (u_char)'\362', (u_char)'\363',
	(u_char)'\364', (u_char)'\365', (u_char)'\366', (u_char)'\367',
	(u_char)'\370', (u_char)'\371', (u_char)'\372', (u_char)'\373',
	(u_char)'\374', (u_char)'\375', (u_char)'\376', (u_char)'\377',
};

static int
pcap_strcasecmp(const char *s1, const char *s2)
{
	register const u_char	*cm = charmap,
				*us1 = (u_char *)s1,
				*us2 = (u_char *)s2;

	while (cm[*us1] == cm[*us2++])
		if (*us1++ == '\0')
			return(0);
	return (cm[*us1] - cm[*--us2]);
}

int
pcap_datalink_name_to_val(const char *name)
{
	int i;

	for (i = 0; dlt_choices[i].name != NULL; i++) {
		if (pcap_strcasecmp(dlt_choices[i].name + sizeof("DLT_") - 1,
		    name) == 0)
			return (dlt_choices[i].dlt);
	}
	return (-1);
}

const char *
pcap_datalink_val_to_name(int dlt)
{
	int i;

	for (i = 0; dlt_choices[i].name != NULL; i++) {
		if (dlt_choices[i].dlt == dlt)
			return (dlt_choices[i].name + sizeof("DLT_") - 1);
	}
	return (NULL);
}

int
pcap_snapshot(pcap_t *p)
{
	return (p->snapshot);
}

int
pcap_is_swapped(pcap_t *p)
{
	return (p->sf.swapped);
}

int
pcap_major_version(pcap_t *p)
{
	return (p->sf.version_major);
}

int
pcap_minor_version(pcap_t *p)
{
	return (p->sf.version_minor);
}

FILE *
pcap_file(pcap_t *p)
{
	return (p->sf.rfile);
}

int
pcap_fileno(pcap_t *p)
{
#ifndef WIN32
	return (p->fd);
#else
	if (p->adapter != NULL)
		return ((int)(DWORD)p->adapter->hFile);
	else
		return (-1);
#endif
}

void
pcap_perror(pcap_t *p, char *prefix)
{
	fprintf(stderr, "%s: %s\n", prefix, p->errbuf);
}

char *
pcap_geterr(pcap_t *p)
{
	return (p->errbuf);
}

/*
 * NOTE: in the future, these may need to call platform-dependent routines,
 * e.g. on platforms with memory-mapped packet-capture mechanisms where
 * "pcap_read()" uses "select()" or "poll()" to wait for packets to arrive.
 */
int
pcap_getnonblock(pcap_t *p, char *errbuf)
{
#ifndef WIN32
	int fdflags;
#endif

	if (p->sf.rfile != NULL) {
		/*
		 * This is a savefile, not a live capture file, so
		 * never say it's in non-blocking mode.
		 */
		return (0);
	}
#ifndef WIN32
	fdflags = fcntl(p->fd, F_GETFL, 0);
	if (fdflags == -1) {
		snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "F_GETFL: %s",
		    pcap_strerror(errno));
		return (-1);
	}
	if (fdflags & O_NONBLOCK)
		return (1);
	else
		return (0);
#else
	return (p->nonblock);
#endif
}

int
pcap_setnonblock(pcap_t *p, int nonblock, char *errbuf)
{
#ifndef WIN32
	int fdflags;
#else
	int newtimeout;
#endif

	if (p->sf.rfile != NULL) {
		/*
		 * This is a savefile, not a live capture file, so
		 * ignore requests to put it in non-blocking mode.
		 */
		return (0);
	}
#ifndef WIN32
	fdflags = fcntl(p->fd, F_GETFL, 0);
	if (fdflags == -1) {
		snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "F_GETFL: %s",
		    pcap_strerror(errno));
		return (-1);
	}
	if (nonblock)
		fdflags |= O_NONBLOCK;
	else
		fdflags &= ~O_NONBLOCK;
	if (fcntl(p->fd, F_SETFL, fdflags) == -1) {
		snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "F_SETFL: %s",
		    pcap_strerror(errno));
		return (-1);
	}
#else
	if (nonblock) {
		/*
		 * Set the read timeout to -1 for non-blocking mode.
		 */
		newtimeout = -1;
	} else {
		/*
		 * Restore the timeout set when the device was opened.
		 * (Note that this may be -1, in which case we're not
		 * really leaving non-blocking mode.)
		 */
		newtimeout = p->timeout;
	}
	if (!PacketSetReadTimeout(p->adapter, newtimeout)) {
		snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
		    "PacketSetReadTimeout: %s", pcap_win32strerror());
		return (-1);
	}
	p->nonblock = (newtimeout == -1);
#endif
	return (0);
}

#ifdef WIN32
/*
 * Generate a string for the last Win32-specific error (i.e. an error generated when 
 * calling a Win32 API).
 * For errors occurred during standard C calls, we still use pcap_strerror()
 */
char *
pcap_win32strerror(void)
{
	DWORD error;
	static char errbuf[PCAP_ERRBUF_SIZE+1];
	int errlen;

	error = GetLastError();
	FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM, NULL, error, 0, errbuf,
	    PCAP_ERRBUF_SIZE, NULL);

	/*
	 * "FormatMessage()" "helpfully" sticks CR/LF at the end of the
	 * message.  Get rid of it.
	 */
	errlen = strlen(errbuf);
	if (errlen >= 2) {
		errbuf[errlen - 1] = '\0';
		errbuf[errlen - 2] = '\0';
	}
	return (errbuf);
}
#endif

/*
 * Not all systems have strerror().
 */
char *
pcap_strerror(int errnum)
{
#ifdef HAVE_STRERROR
	return (strerror(errnum));
#else
	extern int sys_nerr;
	extern const char *const sys_errlist[];
	static char ebuf[20];

	if ((unsigned int)errnum < sys_nerr)
		return ((char *)sys_errlist[errnum]);
	(void)snprintf(ebuf, sizeof ebuf, "Unknown error: %d", errnum);
	return(ebuf);
#endif
}

pcap_t *
pcap_open_dead(int linktype, int snaplen)
{
	pcap_t *p;

	p = malloc(sizeof(*p));
	if (p == NULL)
		return NULL;
	memset (p, 0, sizeof(*p));
#ifndef WIN32
	p->fd = -1;
#else
	p->adapter = NULL;
#endif /* WIN32 */
	p->snapshot = snaplen;
	p->linktype = linktype;
	return p;
}

void
pcap_close(pcap_t *p)
{
#ifdef REMOTE
	if (p->rmt_clientside)
		pcap_close_remote(p);
#endif

	/*XXX*/
#ifndef WIN32
	if (p->fd >= 0) {
#ifdef linux
		pcap_close_linux(p);
#endif
		close(p->fd);
	}
#else /* WIN32 */
	if (p->adapter != NULL) {
		PacketCloseAdapter(p->adapter);
		p->adapter = NULL;
	}
#endif /* WIN32 */
	if (p->sf.rfile != NULL) {
		if (p->sf.rfile != stdin)
			(void)fclose(p->sf.rfile);
		if (p->sf.base != NULL)
			free(p->sf.base);
	} else if (p->buffer != NULL)
		free(p->buffer);
	if (p->dlt_list != NULL)
		free(p->dlt_list);

	pcap_freecode(&p->fcode);
	free(p);
}