cpp/openttd-patchpack/source Changeset - r25242:16241601aa3b

Changeset - r25242:16241601aa3b

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Rubidium - 3 years ago 2021-04-18 07:01:27
rubidium@openttd.org

Codechange: move more logic about packet size validity and reading into Packet

4 files changed with 29 insertions and 13 deletions:

src/network/core/packet.cpp

src/network/core/packet.h

src/network/core/tcp.cpp

src/network/core/udp.cpp

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src/network/core/packet.cpp

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@@ @@ -178,28 +178,45 @@ bool Packet::CanReadFromPacket(uint byte @@
+	}
 	return true;
+}
 /**
  * Reads the packet size from the raw packet and stores it in the packet->size
  * Check whether the packet, given the position of the "write" pointer, has read
  * enough of the packet to contain its size.
  * @return True iff there is enough data in the packet to contain the packet's size.
  */
 void Packet::ReadRawPacketSize()
 bool Packet::HasPacketSizeData() const
+{
 	return this->pos >= sizeof(PacketSize);
+}
 /**
  * Reads the packet size from the raw packet and stores it in the packet->size
  * @return True iff the packet size seems plausible.
  */
 bool Packet::ParsePacketSize()
+{
 	assert(this->cs != nullptr && this->next == nullptr);
 	this->size  = (PacketSize)this->buffer[0];
 	this->size += (PacketSize)this->buffer[1] << 8;
 	/* If the size of the packet is less than the bytes required for the size and type of
 	 * the packet, or more than the allowed limit, then something is wrong with the packet.
 	 * In those cases the packet can generally be regarded as containing garbage data. */
 	if (this->size < sizeof(PacketSize) + sizeof(PacketType) || this->size > SEND_MTU) return false;
 	this->pos = sizeof(PacketSize);
 	return true;
+}
 /**
  * Prepares the packet so it can be read
  */
 void Packet::PrepareToRead()
+{
 	this->ReadRawPacketSize();
 	/* Put the position on the right place */
 	this->pos = sizeof(PacketSize);
+}
 /**
  * Read a boolean from the packet.

src/network/core/packet.h

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@@ @@ -68,13 +68,14 @@ public: @@
 	void Send_uint16(uint16 data);
 	void Send_uint32(uint32 data);
 	void Send_uint64(uint64 data);
 	void Send_string(const char *data);
 	/* Reading/receiving of packets */
 	void ReadRawPacketSize();
 	bool HasPacketSizeData() const;
 	bool ParsePacketSize();
 	void PrepareToRead();
 	bool   CanReadFromPacket (uint bytes_to_read);
 	bool   Recv_bool  ();
 	uint8  Recv_uint8 ();
 	uint16 Recv_uint16();

src/network/core/tcp.cpp

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@@ @@ -152,14 +152,14 @@ Packet *NetworkTCPSocketHandler::Receive @@
 		this->packet_recv = new Packet(this);
+	}
 	Packet *p = this->packet_recv;
 	/* Read packet size */
 	if (p->pos < sizeof(PacketSize)) {
 		while (p->pos < sizeof(PacketSize)) {
 	if (!p->HasPacketSizeData()) {
 		while (!p->HasPacketSizeData()) {
 		/* Read the size of the packet */
 			res = recv(this->sock, (char*)p->buffer + p->pos, sizeof(PacketSize) - p->pos, 0);
 			if (res == -1) {
 				int err = GET_LAST_ERROR();
 				if (err != EWOULDBLOCK) {
 					/* Something went wrong... (104 is connection reset by peer) */
@@ @@ -175,16 +175,14 @@ Packet *NetworkTCPSocketHandler::Receive @@
 				this->CloseConnection();
 				return nullptr;
+			}
 			p->pos += res;
+		}
 		/* Read the packet size from the received packet */
 		p->ReadRawPacketSize();
 		if (p->size > SEND_MTU) {
 		/* Parse the size in the received packet and if not valid, close the connection. */
 		if (!p->ParsePacketSize()) {
 			this->CloseConnection();
 			return nullptr;
+		}
+	}
 	/* Read rest of packet */

src/network/core/udp.cpp

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@@ @@ -131,20 +131,20 @@ void NetworkUDPSocketHandler::ReceivePac @@
 			if (nbytes <= 2) continue; // Invalid data; try next packet
 #ifdef __EMSCRIPTEN__
 			client_len = FixAddrLenForEmscripten(client_addr);
 #endif
 			NetworkAddress address(client_addr, client_len);
 			p.PrepareToRead();
 			/* If the size does not match the packet must be corrupted.
 			 * Otherwise it will be marked as corrupted later on. */
 			if (nbytes != p.size) {
+			if (!p.ParsePacketSize() || nbytes != p.size) {
 				DEBUG(net, 1, "received a packet with mismatching size from %s", address.GetAddressAsString().c_str());
 				continue;
+			}
 			p.PrepareToRead();
 			/* Handle the packet */
 			this->HandleUDPPacket(&p, &address);
+		}
+	}
+}

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