some NetBufferUtility revamp.

- introduced base NetBufferFieldReader which deals with obtaining a continuguous field to deal with.
 - renamed Detach() to Sync() to better express the fact that we may be writing to the buffer.
 - Fixed IPv4's and ICMP's checksum calculation as it assumed the underlying header was contiguous.
 - ICMP is now able to reply to ICMP Echo Requests which were split across data nodes.
 - in split_buffer(), make sure we were able to trim() the new buffer before damaging the original one.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@20657 a95241bf-73f2-0310-859d-f6bbb57e9c96

headers/private/net/NetBufferUtilities.h

@@ -16,94 +16,26 @@ class NetBufferModuleGetter {
 		static net_buffer_module_info *Get() { return gBufferModule; }
 };
 
-//! A class to retrieve and remove a header from a buffer
-template<typename Type, typename Module = NetBufferModuleGetter > class NetBufferHeader {
+//! A class to access a field safely across node boundaries
+template<typename Type, int Offset, typename Module = NetBufferModuleGetter>
+class NetBufferFieldReader {
 	public:
-		NetBufferHeader(net_buffer *buffer)
+		NetBufferFieldReader(net_buffer *buffer)
 			:
-			fBuffer(buffer)
+			fBuffer(buffer),
+			fStatus(B_BAD_VALUE)
 		{
-		}
-
-		~NetBufferHeader()
-		{
-			Remove();
-		}
-
-		status_t
-		Status()
-		{
-			return fBuffer->size < sizeof(Type) ? B_BAD_VALUE : B_OK;
-		}
-
-		status_t
-		SetTo(net_buffer *buffer)
-		{
-			fBuffer = buffer;
-			return Status();
-		}
-
-		Type &
-		Data()
-		{
-			Type *data;
-			if (Module::Get()->direct_access(fBuffer, 0, sizeof(Type),
-					(void **)&data) == B_OK)
-				return *data;
-
-			Module::Get()->read(fBuffer, 0, &fDataBuffer, sizeof(Type));
-			return fDataBuffer;
-		}
-
-		void
-		Remove()
-		{
-			Remove(sizeof(Type));
-		}
-
-		void
-		Remove(size_t bytes)
-		{
-			if (fBuffer != NULL) {
-				Module::Get()->remove_header(fBuffer, bytes);
-				fBuffer = NULL;
+			if ((Offset + sizeof(Type)) <= buffer->size) {
+				fStatus = Module::Get()->direct_access(fBuffer, Offset,
+					sizeof(Type), (void **)&fData);
+				if (fStatus != B_OK) {
+					fData = NULL;
+					fStatus = Module::Get()->read(fBuffer, Offset,
+						&fDataBuffer, sizeof(Type));
+				}
 			}
 		}
 
-		void
-		Detach()
-		{
-			fBuffer = NULL;
-		}
-
-	private:
-		net_buffer	*fBuffer;
-		Type		fDataBuffer;
-};
-
-//! A class to access a header safely across data node boundaries
-template<typename Type, typename Module = NetBufferModuleGetter>
-class NetBufferSafeHeader {
-	public:
-		NetBufferSafeHeader(net_buffer *buffer)
-			:
-			fBuffer(buffer)
-		{
-			fStatus = Module::Get()->direct_access(fBuffer, 0,
-				sizeof(Type), (void **)&fData);
-			if (fStatus != B_OK) {
-				fData = NULL;
-				fStatus = Module::Get()->read(fBuffer, 0, &fDataBuffer,
-					sizeof(Type));
-			}
-		}
-
-		~NetBufferSafeHeader()
-		{
-			if (fBuffer != NULL)
-				Detach();
-		}
-
 		status_t
 		Status()
 		{
@@ -119,16 +51,33 @@ class NetBufferSafeHeader {
 			return fDataBuffer;
 		}
 
-		void
-		Detach()
+		Type *
+		operator->()
 		{
+			return &Data();
+		}
+
+		Type &
+		operator*()
+		{
+			return Data();
+		}
+
+		void
+		Sync()
+		{
+			if (fBuffer == NULL)
+				return;
+
 			if (fData == NULL)
-				Module::Get()->write(fBuffer, 0, &fDataBuffer, sizeof(Type));
+				Module::Get()->write(fBuffer, Offset, &fDataBuffer,
+					sizeof(Type));
+
 			fBuffer = NULL;
 		}
 
 	protected:
-		NetBufferSafeHeader() {}
+		NetBufferFieldReader() {}
 
 		net_buffer	*fBuffer;
 		status_t	fStatus;
@@ -136,9 +85,58 @@ class NetBufferSafeHeader {
 		Type		fDataBuffer;
 };
 
+template<typename Type, int Offset, typename Module = NetBufferModuleGetter>
+class NetBufferField : public NetBufferFieldReader<Type, Offset, Module> {
+	public:
+		NetBufferField(net_buffer *buffer)
+			: NetBufferFieldReader<Type, Offset, Module>(buffer)
+		{}
+
+		~NetBufferField()
+		{
+			Sync();
+		}
+};
+
+template<typename Type, typename Module = NetBufferModuleGetter>
+class NetBufferHeaderReader : public NetBufferFieldReader<Type, 0, Module> {
+	public:
+		NetBufferHeaderReader(net_buffer *buffer)
+			: NetBufferFieldReader<Type, 0, Module>(buffer)
+		{}
+
+		void
+		Remove()
+		{
+			Remove(sizeof(Type));
+		}
+
+		void
+		Remove(size_t bytes)
+		{
+			if (fBuffer != NULL) {
+				Module::Get()->remove_header(fBuffer, bytes);
+				fBuffer = NULL;
+			}
+		}
+};
+
+template<typename Type, typename Module = NetBufferModuleGetter>
+class NetBufferHeaderRemover : public NetBufferHeaderReader<Type, Module> {
+	public:
+		NetBufferHeaderRemover(net_buffer *buffer)
+			: NetBufferHeaderReader<Type, Module>(buffer)
+		{}
+
+		~NetBufferHeaderRemover()
+		{
+			Remove();
+		}
+};
+
 //! A class to add a header to a buffer
 template<typename Type, typename Module = NetBufferModuleGetter>
-class NetBufferPrepend : public NetBufferSafeHeader<Type, Module> {
+class NetBufferPrepend : public NetBufferFieldReader<Type, 0, Module> {
 	public:
 		NetBufferPrepend(net_buffer *buffer, size_t size = 0)
 		{
@@ -150,6 +148,11 @@ class NetBufferPrepend : public NetBufferSafeHeader<Type, Module> {
 
 			fStatus = Module::Get()->prepend_size(buffer, size, (void **)&fData);
 		}
+
+		~NetBufferPrepend()
+		{
+			Sync();
+		}
 };
 
 #endif	// NET_BUFFER_UTILITIES_H

src/add-ons/kernel/network/datalink_protocols/arp/arp.cpp

@@ -353,7 +353,7 @@ arp_receive(void *cookie, net_buffer *buffer)
 {
 	TRACE(("ARP receive\n"));
 
-	NetBufferHeader<arp_header> bufferHeader(buffer);
+	NetBufferHeaderReader<arp_header> bufferHeader(buffer);
 	if (bufferHeader.Status() < B_OK)
 		return bufferHeader.Status();
 
@@ -383,8 +383,6 @@ arp_receive(void *cookie, net_buffer *buffer)
 		|| header.protocol_length != sizeof(in_addr_t))
 		return B_BAD_DATA;
 
-	bufferHeader.Detach();
-
 	// handle packet
 
 	switch (opcode) {

src/add-ons/kernel/network/datalink_protocols/ethernet_frame/ethernet_frame.cpp

@@ -38,7 +38,7 @@ ethernet_deframe(net_device *device, net_buffer *buffer)
 {
 	//dprintf("asked to deframe buffer for device %s\n", device->name);
 
-	NetBufferHeader<ether_header> bufferHeader(buffer);
+	NetBufferHeaderRemover<ether_header> bufferHeader(buffer);
 	if (bufferHeader.Status() < B_OK)
 		return bufferHeader.Status();
 
@@ -138,7 +138,7 @@ ethernet_frame_send_data(net_datalink_protocol *protocol,
 	else
 		memcpy(header.destination, destination.sdl_data, ETHER_ADDRESS_LENGTH);
 
-	bufferHeader.Detach();
+	bufferHeader.Sync();
 		// make sure the framing is already written to the buffer at this point
 
 	return protocol->next->module->send_data(protocol->next, buffer);

src/add-ons/kernel/network/protocols/icmp/icmp.cpp

@@ -48,6 +48,8 @@ struct icmp_header {
 	};
 };
 
+typedef NetBufferField<uint16, offsetof(icmp_header, checksum)> ICMPChecksumField;
+
 #define ICMP_TYPE_ECHO_REPLY	0
 #define ICMP_TYPE_UNREACH		3
 #define ICMP_TYPE_REDIRECT		5
@@ -211,13 +213,11 @@ icmp_receive_data(net_buffer *buffer)
 {
 	TRACE(("ICMP received some data, buffer length %lu\n", buffer->size));
 
-	NetBufferHeader<icmp_header> bufferHeader(buffer);
+	NetBufferHeaderReader<icmp_header> bufferHeader(buffer);
 	if (bufferHeader.Status() < B_OK)
 		return bufferHeader.Status();
 
 	icmp_header &header = bufferHeader.Data();
-	bufferHeader.Detach();
-		// the pointer stays valid after this
 
 	TRACE(("  got type %u, code %u, checksum %u\n", header.type, header.code,
 		ntohs(header.checksum)));
@@ -249,19 +249,18 @@ icmp_receive_data(net_buffer *buffer)
 			memcpy(&reply->destination, &buffer->source, buffer->source.ss_len);
 
 			// There already is an ICMP header, and we'll reuse it
-			icmp_header *header;
-			status_t status = gBufferModule->direct_access(reply,
-				0, sizeof(icmp_header), (void **)&header);
-			if (status == B_OK) {
-				header->type = ICMP_TYPE_ECHO_REPLY;
-				header->code = 0;
-				header->checksum = 0;
-				header->checksum = gBufferModule->checksum(reply, 0, reply->size, true);
-			}
+			NetBufferHeaderReader<icmp_header> header(reply);
 
-			if (status == B_OK)
-				status = domain->module->send_data(NULL, reply);
+			header->type = ICMP_TYPE_ECHO_REPLY;
+			header->code = 0;
+			header->checksum = 0;
 
+			header.Sync();
+
+			ICMPChecksumField checksum(reply);
+			*checksum = gBufferModule->checksum(reply, 0, reply->size, true);
+
+			status_t status = domain->module->send_data(NULL, reply);
 			if (status < B_OK) {
 				gBufferModule->free(reply);
 				return status;

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

@@ -74,6 +74,8 @@ struct ipv4_header {
 typedef DoublyLinkedList<struct net_buffer,
 	DoublyLinkedListCLink<struct net_buffer> > FragmentList;
 
+typedef NetBufferField<uint16, offsetof(ipv4_header, checksum)> IPChecksumField;
+
 struct ipv4_packet_key {
 	in_addr_t	source;
 	in_addr_t	destination;
@@ -560,14 +562,11 @@ send_fragments(ipv4_protocol *protocol, struct net_route *route,
 	TRACE(("ipv4 needs to fragment (size %lu, MTU %lu)...\n",
 		buffer->size, mtu));
 
-	NetBufferHeader<ipv4_header> bufferHeader(buffer);
-	if (bufferHeader.Status() < B_OK)
-		return bufferHeader.Status();
+	NetBufferHeaderReader<ipv4_header> originalHeader(buffer);
+	if (originalHeader.Status() < B_OK)
+		return originalHeader.Status();
 
-	ipv4_header *header = &bufferHeader.Data();
-	bufferHeader.Detach();
-
-	uint16 headerLength = header->HeaderLength();
+	uint16 headerLength = originalHeader->HeaderLength();
 	uint32 bytesLeft = buffer->size - headerLength;
 	uint32 fragmentOffset = 0;
 	status_t status = B_OK;
@@ -576,9 +575,10 @@ send_fragments(ipv4_protocol *protocol, struct net_route *route,
 	if (headerBuffer == NULL)
 		return B_NO_MEMORY;
 
-	bufferHeader.SetTo(headerBuffer);
-	header = &bufferHeader.Data();
-	bufferHeader.Detach();
+	// TODO we need to make sure ipv4_header is contiguous or
+	//      use another construct.
+	NetBufferHeaderReader<ipv4_header> bufferHeader(headerBuffer);
+	ipv4_header *header = &bufferHeader.Data();
 
 	// adapt MTU to be a multiple of 8 (fragment offsets can only be specified this way)
 	mtu -= headerLength;
@@ -671,6 +671,15 @@ receiving_protocol(uint8 protocol)
 }
 
 
+static void
+update_checksum(net_buffer *buffer)
+{
+	IPChecksumField checksum(buffer);
+
+	*checksum = gBufferModule->checksum(buffer, 0, sizeof(ipv4_header), true);
+}
+
+
 //	#pragma mark -
 
 
@@ -955,27 +964,27 @@ ipv4_send_routed_data(net_protocol *_protocol, struct net_route *route,
 
 		header.destination = ((sockaddr_in *)&buffer->destination)->sin_addr.s_addr;
 
-		header.checksum = gBufferModule->checksum(buffer, 0,
-			sizeof(ipv4_header), true);
-		//dump_ipv4_header(header);
-
-		bufferHeader.Detach();
+		bufferHeader.Sync();
 			// make sure the IP-header is already written to the
 			// buffer at this point
+
+		update_checksum(buffer);
+		//dump_ipv4_header(header);
+
 	} else {
 		// if IP_HDRINCL, check if the source address is set
-		NetBufferHeader<ipv4_header> bufferHeader(buffer);
-		if (bufferHeader.Status() < B_OK)
-			return bufferHeader.Status();
+		NetBufferHeaderReader<ipv4_header> header(buffer);
+		if (header.Status() < B_OK)
+			return header.Status();
 
-		ipv4_header &header = bufferHeader.Data();
-		if (header.source == 0) {
-			header.source = source.sin_addr.s_addr;
-			header.checksum = gBufferModule->checksum(buffer,
-				sizeof(ipv4_header), sizeof(ipv4_header), true);
+		if (header->source == 0) {
+			header->source = source.sin_addr.s_addr;
+			header->checksum = 0;
+
+			header.Sync();
+
+			update_checksum(buffer);
 		}
-
-		bufferHeader.Detach();
 	}
 
 	if (buffer->size > 0xffff)
@@ -1079,12 +1088,11 @@ ipv4_receive_data(net_buffer *buffer)
 {
 	TRACE(("IPv4 received a packet (%p) of %ld size!\n", buffer, buffer->size));
 
-	NetBufferHeader<ipv4_header> bufferHeader(buffer);
+	NetBufferHeaderReader<ipv4_header> bufferHeader(buffer);
 	if (bufferHeader.Status() < B_OK)
 		return bufferHeader.Status();
 
 	ipv4_header &header = bufferHeader.Data();
-	bufferHeader.Detach();
 	//dump_ipv4_header(header);
 
 	if (header.version != IP_VERSION)

src/add-ons/kernel/network/protocols/tcp/tcp.cpp

@@ -39,6 +39,9 @@
 #endif
 
 
+typedef NetBufferField<uint16, offsetof(tcp_header, checksum)> TCPChecksumField;
+
+
 net_domain *gDomain;
 net_address_module_info *gAddressModule;
 net_buffer_module_info *gBufferModule;
@@ -150,7 +153,7 @@ add_tcp_header(tcp_segment_header &segment, net_buffer *buffer)
 
 	// we must detach before calculating the checksum as we may
 	// not have a contiguous buffer.
-	bufferHeader.Detach();
+	bufferHeader.Sync();
 
 	if (optionsLength > 0)
 		gBufferModule->write(buffer, sizeof(tcp_header), optionsBuffer, optionsLength);
@@ -167,9 +170,8 @@ add_tcp_header(tcp_segment_header &segment, net_buffer *buffer)
 		<< (uint16)htons(buffer->size)
 		<< Checksum::BufferHelper(buffer, gBufferModule);
 
-	// we are pretty sure the header is there.
-	NetBufferSafeHeader<tcp_header> headerRef(buffer);
-	headerRef.Data().checksum = checksum;
+	TCPChecksumField checksumField(buffer);
+	*checksumField = checksum;
 
 	return B_OK;
 }
@@ -507,7 +509,7 @@ tcp_receive_data(net_buffer *buffer)
 	if (gDomain == NULL && set_domain(buffer->interface) != B_OK)
 		return B_ERROR;
 
-	NetBufferHeader<tcp_header> bufferHeader(buffer);
+	NetBufferHeaderReader<tcp_header> bufferHeader(buffer);
 	if (bufferHeader.Status() < B_OK)
 		return bufferHeader.Status();
 

src/add-ons/kernel/network/protocols/udp/udp.cpp

@@ -440,7 +440,7 @@ UdpEndpointManager::DemuxIncomingBuffer(net_buffer *buffer)
 status_t
 UdpEndpointManager::ReceiveData(net_buffer *buffer)
 {
-	NetBufferHeader<udp_header> bufferHeader(buffer);
+	NetBufferHeaderReader<udp_header> bufferHeader(buffer);
 	if (bufferHeader.Status() < B_OK)
 		return bufferHeader.Status();
 

src/add-ons/kernel/network/stack/net_buffer.cpp

@@ -464,9 +464,10 @@ split_buffer(net_buffer *from, uint32 offset)
 
 	TRACE(("split_buffer(buffer %p -> %p, offset %ld)\n", from, buffer, offset));
 
-	if (remove_header(from, offset) == B_OK
-		&& trim_data(buffer, offset) == B_OK)
-		return buffer;
+	if (trim_data(buffer, offset) == B_OK) {
+		if (remove_header(from, offset) == B_OK)
+			return buffer;
+	}
 
 	free_buffer(buffer);
 	return NULL;