inet.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.

	} else
		curaddr->broadaddr = NULL;

	if (dstaddr != NULL) {
		curaddr->dstaddr = dup_sockaddr(dstaddr, dstaddr_size);
		if (curaddr->dstaddr == NULL) {
			(void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
			    "malloc: %s", pcap_strerror(errno));
			free(curaddr);
			return (-1);
		}
	} else
		curaddr->dstaddr = NULL;

	/*
	 * Find the end of the list of addresses.
	 */
	for (prevaddr = curdev->addresses; prevaddr != NULL; prevaddr = nextaddr) {
		nextaddr = prevaddr->next;
		if (nextaddr == NULL) {
			/*
			 * This is the end of the list.
			 */
			break;
		}
	}

	if (prevaddr == NULL) {
		/*
		 * The list was empty; this is the first member.
		 */
		curdev->addresses = curaddr;
	} else {
		/*
		 * "prevaddr" is the last member of the list; append
		 * this member to it.
		 */
		prevaddr->next = curaddr;
	}

	return (0);
}

int
pcap_add_if(pcap_if_t **devlist, char *name, u_int flags,
    const char *description, char *errbuf)
{
	pcap_if_t *curdev;

	return (add_or_find_if(&curdev, devlist, name, flags, description,
	    errbuf));
}


/*
 * Free a list of interfaces.
 */
void
pcap_freealldevs(pcap_if_t *alldevs)
{
	pcap_if_t *curdev, *nextdev;
	pcap_addr_t *curaddr, *nextaddr;

	for (curdev = alldevs; curdev != NULL; curdev = nextdev) {
		nextdev = curdev->next;

		/*
		 * Free all addresses.
		 */
		for (curaddr = curdev->addresses; curaddr != NULL; curaddr = nextaddr) {
			nextaddr = curaddr->next;
			if (curaddr->addr)
				free(curaddr->addr);
			if (curaddr->netmask)
				free(curaddr->netmask);
			if (curaddr->broadaddr)
				free(curaddr->broadaddr);
			if (curaddr->dstaddr)
				free(curaddr->dstaddr);
			free(curaddr);
		}

		/*
		 * Free the name string.
		 */
		free(curdev->name);

		/*
		 * Free the description string, if any.
		 */
		if (curdev->description != NULL)
			free(curdev->description);

		/*
		 * Free the interface.
		 */
		free(curdev);
	}
}

#ifndef WIN32

/*
 * Return the name of a network interface attached to the system, or NULL
 * if none can be found.  The interface must be configured up; the
 * lowest unit number is preferred; loopback is ignored.
 */
char *
pcap_lookupdev(errbuf)
	register char *errbuf;
{
	pcap_if_t *alldevs;
/* for old BSD systems, including bsdi3 */
#ifndef IF_NAMESIZE
#define IF_NAMESIZE IFNAMSIZ
#endif
	static char device[IF_NAMESIZE + 1];
	char *ret;

	if (pcap_findalldevs(&alldevs, errbuf) == -1)
		return (NULL);

	if (alldevs == NULL || (alldevs->flags & PCAP_IF_LOOPBACK)) {
		/*
		 * There are no devices on the list, or the first device
		 * on the list is a loopback device, which means there
		 * are no non-loopback devices on the list.  This means
		 * we can't return any device.
		 *
		 * XXX - why not return a loopback device?  If we can't
		 * capture on it, it won't be on the list, and if it's
		 * on the list, there aren't any non-loopback devices,
		 * so why not just supply it as the default device?
		 */
		(void)strlcpy(errbuf, "no suitable device found",
		    PCAP_ERRBUF_SIZE);
		ret = NULL;
	} else {
		/*
		 * Return the name of the first device on the list.
		 */
		(void)strlcpy(device, alldevs->name, sizeof(device));
		ret = device;
	}

	pcap_freealldevs(alldevs);
	return (ret);
}

int
pcap_lookupnet(device, netp, maskp, errbuf)
	register const char *device;
	register bpf_u_int32 *netp, *maskp;
	register char *errbuf;
{
	register int fd;
	register struct sockaddr_in *sin;
	struct ifreq ifr;

	/*
	 * The pseudo-device "any" listens on all interfaces and therefore
	 * has the network address and -mask "0.0.0.0" therefore catching
	 * all traffic. Using NULL for the interface is the same as "any".
	 */
	if (!device || strcmp(device, "any") == 0
#ifdef HAVE_DAG_API
	    || strstr(device, "dag") != NULL
#endif
	    ) {
		*netp = *maskp = 0;
		return 0;
	}

	fd = socket(AF_INET, SOCK_DGRAM, 0);
	if (fd < 0) {
		(void)snprintf(errbuf, PCAP_ERRBUF_SIZE, "socket: %s",
		    pcap_strerror(errno));
		return (-1);
	}
	memset(&ifr, 0, sizeof(ifr));
#ifdef linux
	/* XXX Work around Linux kernel bug */
	ifr.ifr_addr.sa_family = AF_INET;
#endif
	(void)strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
	if (ioctl(fd, SIOCGIFADDR, (char *)&ifr) < 0) {
		if (errno == EADDRNOTAVAIL) {
			(void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
			    "%s: no IPv4 address assigned", device);
		} else {
			(void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
			    "SIOCGIFADDR: %s: %s",
			    device, pcap_strerror(errno));
		}
		(void)close(fd);
		return (-1);
	}
	sin = (struct sockaddr_in *)&ifr.ifr_addr;
	*netp = sin->sin_addr.s_addr;
	if (ioctl(fd, SIOCGIFNETMASK, (char *)&ifr) < 0) {
		(void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
		    "SIOCGIFNETMASK: %s: %s", device, pcap_strerror(errno));
		(void)close(fd);
		return (-1);
	}
	(void)close(fd);
	*maskp = sin->sin_addr.s_addr;
	if (*maskp == 0) {
		if (IN_CLASSA(*netp))
			*maskp = IN_CLASSA_NET;
		else if (IN_CLASSB(*netp))
			*maskp = IN_CLASSB_NET;
		else if (IN_CLASSC(*netp))
			*maskp = IN_CLASSC_NET;
		else {
			(void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
			    "inet class for 0x%x unknown", *netp);
			return (-1);
		}
	}
	*netp &= *maskp;
	return (0);
}

#else /* WIN32 */

/*
 * Return the name of a network interface attached to the system, or NULL
 * if none can be found.  The interface must be configured up; the
 * lowest unit number is preferred; loopback is ignored.
 */
char *
pcap_lookupdev(errbuf)
	register char *errbuf;
{
	DWORD dwVersion;
	DWORD dwWindowsMajorVersion;
	dwVersion = GetVersion();	/* get the OS version */
	dwWindowsMajorVersion = (DWORD)(LOBYTE(LOWORD(dwVersion)));
	
	if (dwVersion >= 0x80000000 && dwWindowsMajorVersion >= 4) {
		/*
		 * Windows 95, 98, ME.
		 */
		ULONG NameLength = 8192;
		static char AdaptersName[8192];
		
		if (PacketGetAdapterNames(AdaptersName,&NameLength) )
			return (AdaptersName);
		else
			return NULL;
	} else {
		/*
		 * Windows NT (NT 4.0, W2K, WXP). Convert the names to UNICODE for backward compatibility
		 */
		ULONG NameLength = 8192;
		static WCHAR AdaptersName[8192];
		char *tAstr;
		WCHAR *tUstr;
		WCHAR *TAdaptersName = (WCHAR*)malloc(8192 * sizeof(WCHAR));
		int NAdapts = 0;

		if(TAdaptersName == NULL)
		{
			(void)snprintf(errbuf, PCAP_ERRBUF_SIZE, "memory allocation failure");
			return NULL;
		}

		if ( !PacketGetAdapterNames((PTSTR)TAdaptersName,&NameLength) )
		{
			(void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
				"PacketGetAdapterNames: %s",
				pcap_win32strerror());
			free(TAdaptersName);
			return NULL;
		}


		tAstr = (char*)TAdaptersName;
		tUstr = (WCHAR*)AdaptersName;

		/*
		 * Convert and copy the device names
		 */
		while(sscanf(tAstr, "%S", tUstr) > 0)
		{
			tAstr += strlen(tAstr) + 1;
			tUstr += wcslen(tUstr) + 1;
			NAdapts ++;
		}

		tAstr++;
		*tUstr = 0;
		tUstr++;

		/*
		 * Copy the descriptions
		 */
		while(NAdapts--)
		{
			strcpy((char*)tUstr, tAstr);
			(char*)tUstr += strlen(tAstr) + 1;;
			tAstr += strlen(tAstr) + 1;
		}

		free(TAdaptersName);
		return (char *)(AdaptersName);
	}	
}


int
pcap_lookupnet(device, netp, maskp, errbuf)
	const register char *device;
	register bpf_u_int32 *netp, *maskp;
	register char *errbuf;
{
	/* 
	 * We need only the first IPv4 address, so we must scan the array returned by PacketGetNetInfo()
	 * in order to skip non IPv4 (i.e. IPv6 addresses)
	 */
	npf_if_addr if_addrs[MAX_NETWORK_ADDRESSES];
	LONG if_addr_size = 1;
	struct sockaddr_in *t_addr;
	unsigned int i;

	if (!PacketGetNetInfoEx((void *)device, if_addrs, &if_addr_size)) {
		*netp = *maskp = 0;
		return (0);
	}

	for(i=0; i<MAX_NETWORK_ADDRESSES; i++)
	{
		if(if_addrs[i].IPAddress.ss_family == AF_INET)
		{
			t_addr = (struct sockaddr_in *) &(if_addrs[i].IPAddress);
			*netp = t_addr->sin_addr.S_un.S_addr;
			t_addr = (struct sockaddr_in *) &(if_addrs[i].SubnetMask);
			*maskp = t_addr->sin_addr.S_un.S_addr;

			*netp &= *maskp;
			return (0);
		}
				
	}

	*netp = *maskp = 0;
	return (0);
}

#endif /* WIN32 */