fixing #3712:

* Since r30000, a net_socket is not zeroed anymore, which in turn
  leaves its two addresses (local and peer) in an uninitialized,
  but correct state - marking their state with ss_len == 0. 
  However, this state was not properly detected in some ipv4-address
  functions, especially not the one that creates a hash value from
  those two addresses.
  This basically caused UDP to stop working, as here the peer address
  (as opposed to TCP) is usually not explicitly initialized.
  Adjusting the ipv4-address functions accordingly fixes the problem,
  such that DHCP (and the rest of UDP) should now work again.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@30175 a95241bf-73f2-0310-859d-f6bbb57e9c96

src/add-ons/kernel/network/protocols/ipv4/ipv4_address.cpp

@@ -30,6 +30,8 @@
 	result of \a from & \a mask).
 	\return B_OK if the address could be copied
 	\return B_NO_MEMORY if the new address could not be allocated
+	\return B_BAD_VALUE if any of \a from or \a mask refers to an uninitialized
+			address
 	\return B_MISMATCHED_VALUES if \a address does not match family AF_INET
 */
 static status_t
@@ -47,6 +49,8 @@ ipv4_copy_address(const sockaddr *from, sockaddr **to,
 	} else {
 		if (from == NULL)
 			return B_OK;
+		if (from->sa_len == 0 || (mask != NULL && mask->sa_len == 0))
+			return B_BAD_VALUE;
 		if (from->sa_family != AF_INET)
 			return B_MISMATCHED_VALUES;
 
@@ -69,12 +73,14 @@ ipv4_copy_address(const sockaddr *from, sockaddr **to,
 	Routing utility function: applies \a mask to given \a address and puts
 	the resulting address into \a result.
 	\return B_OK if the mask has been applied
-	\return B_BAD_VALUE if \a address or \a mask is NULL
+	\return B_BAD_VALUE if \a address is NULL or if any of \a address or \a mask
+			refers to an uninitialized address
 */
 static status_t
 ipv4_mask_address(const sockaddr *address, const sockaddr *mask, sockaddr *result)
 {
-	if (address == NULL || result == NULL)
+	if (address == NULL || address->sa_len == 0 || result == NULL
+			|| (mask != NULL && mask->sa_len == 0))
 		return B_BAD_VALUE;
 
 	memcpy(result, address, sizeof(sockaddr_in));
@@ -138,7 +144,8 @@ ipv4_equal_ports(const sockaddr *a, const sockaddr *b)
 /*!
 	Compares the IP-addresses and ports of the two given address structures
 	\a a and \a b.
-	\return true if IP-addresses and ports of \a a and \a b are equal, false if not
+	\return true if IP-addresses and ports of \a a and \a b are equal, false if
+			not
 */
 static bool
 ipv4_equal_addresses_and_ports(const sockaddr *a, const sockaddr *b)
@@ -301,7 +308,7 @@ ipv4_print_address(const sockaddr *_address, char **_buffer, bool printPort)
 static uint16
 ipv4_get_port(const sockaddr *address)
 {
-	if (address == NULL)
+	if (address == NULL || address->sa_len == 0)
 		return 0;
 
 	return ((sockaddr_in *)address)->sin_port;
@@ -311,12 +318,12 @@ ipv4_get_port(const sockaddr *address)
 /*!
 	Sets the port of the given \a address to \a port.
 	\return B_OK if the port has been set
-	\return B_BAD_VALUE if \a address is NULL
+	\return B_BAD_VALUE if \a address is NULL or has not been initialized
 */
 static status_t
 ipv4_set_port(sockaddr *address, uint16 port)
 {
-	if (address == NULL)
+	if (address == NULL || address->sa_len == 0)
 		return B_BAD_VALUE;
 
 	((sockaddr_in *)address)->sin_port = port;
@@ -327,13 +334,14 @@ ipv4_set_port(sockaddr *address, uint16 port)
 /*!
 	Sets \a address to \a from.
 	\return B_OK if \a from has been copied into \a address
-	\return B_BAD_VALUE if either \a address or \a from is NULL
+	\return B_BAD_VALUE if either \a address or \a from is NULL or if the
+			address given in from has not been initialized
 	\return B_MISMATCHED_VALUES if from is not of family AF_INET
 */
 static status_t
 ipv4_set_to(sockaddr *address, const sockaddr *from)
 {
-	if (address == NULL || from == NULL)
+	if (address == NULL || from == NULL || from->sa_len == 0)
 		return B_BAD_VALUE;
 
 	if (from->sa_family != AF_INET)
@@ -345,13 +353,20 @@ ipv4_set_to(sockaddr *address, const sockaddr *from)
 }
 
 
+/*!
+	Updates missing parts in \a address with the values in \a from.
+	\return B_OK if \a address has been updated from \a from
+	\return B_BAD_VALUE if either \a address or \a from is NULL or if the
+			address given in from has not been initialized
+	\return B_MISMATCHED_VALUES if from is not of family AF_INET
+*/
 static status_t
 ipv4_update_to(sockaddr *_address, const sockaddr *_from)
 {
 	sockaddr_in *address = (sockaddr_in *)_address;
 	const sockaddr_in *from = (const sockaddr_in *)_from;
 
-	if (address == NULL || from == NULL)
+	if (address == NULL || from == NULL || from->sin_len == 0)
 		return B_BAD_VALUE;
 
 	if (from->sin_family != AF_INET)
@@ -448,20 +463,27 @@ ipv4_hash_address_pair(const sockaddr *ourAddress, const sockaddr *peerAddress)
 	const sockaddr_in *our = (const sockaddr_in *)ourAddress;
 	const sockaddr_in *peer = (const sockaddr_in *)peerAddress;
 
-	return ((our ? our->sin_port : 0) | ((peer ? peer->sin_port : 0) << 16))
+	bool haveOur = our && our->sin_len != 0;
-		^ (our ? our->sin_addr.s_addr : 0) ^ (peer ? peer->sin_addr.s_addr : 0);
+	bool havePeer = peer && peer->sin_len != 0;
+
+	return
+		((haveOur ? our->sin_port : 0)
+			| ((havePeer ? peer->sin_port : 0) << 16))
+		^ (haveOur ? our->sin_addr.s_addr : 0)
+		^ (havePeer ? peer->sin_addr.s_addr : 0);
 }
 
 
 /*!
 	Adds the given \a address to the IP-checksum \a checksum.
 	\return B_OK if \a address has been added to the checksum
-	\return B_BAD_VALUE if either \a address or \a checksum is NULL
+	\return B_BAD_VALUE if either \a address or \a checksum is NULL or if
+	        the given address is not initialized
 */
 static status_t
 ipv4_checksum_address(struct Checksum *checksum, const sockaddr *address)
 {
-	if (checksum == NULL || address == NULL)
+	if (checksum == NULL || address == NULL || address->sa_len == 0)
 		return B_BAD_VALUE;
 
 	(*checksum) << (uint32)((sockaddr_in *)address)->sin_addr.s_addr;