cpp/openttd-patchpack/source Changeset - r25244:61183b73d88e

Changeset - r25244:61183b73d88e

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Rubidium - 3 years ago 2021-04-18 07:55:00
rubidium@openttd.org

Codechange: encapsulate reading data from sockets into Packets to prevent packet state modifications outside of the Packet

4 files changed with 75 insertions and 15 deletions:

src/network/core/packet.cpp

src/network/core/packet.h

src/network/core/tcp.cpp

src/network/core/udp.cpp

0 comments (0 inline, 0 general)

src/network/core/packet.cpp

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@@ @@ -17,17 +17,24 @@ @@
 #include "../../safeguards.h"
 /**
  * Create a packet that is used to read from a network socket
  * @param cs the socket handler associated with the socket we are reading from
  * Create a packet that is used to read from a network socket.
  * @param cs                The socket handler associated with the socket we are reading from.
  * @param initial_read_size The initial amount of data to transfer from the socket into the
  *                          packet. This defaults to just the required bytes to determine the
  *                          packet's size. That default is the wanted for streams such as TCP
  *                          as you do not want to read data of the next packet yet. For UDP
  *                          you need to read the whole packet at once otherwise you might
  *                          loose some the data of the packet, so there you pass the maximum
  *                          size for the packet you expect from the network.
  */
 Packet::Packet(NetworkSocketHandler *cs)
+Packet::Packet(NetworkSocketHandler *cs, size_t initial_read_size)
+{
 	assert(cs != nullptr);
 	this->cs     = cs;
 	this->next   = nullptr;
 	this->pos    = 0; // We start reading from here
-	this->size   = 0;
+	this->size   = static_cast<int>(initial_read_size);
 	this->buffer = MallocT<byte>(SEND_MTU);
+}
@@ @@ -336,3 +343,12 @@ void Packet::Recv_string(char *buffer, s @@
 	str_validate(bufp, last, settings);
+}
 /**
  * Get the amount of bytes that are still available for the Transfer functions.
  * @return The number of bytes that still have to be transfered.
  */
 size_t Packet::RemainingBytesToTransfer() const
+{
 	return this->size - this->pos;
+}

src/network/core/packet.h

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@@ @@ -12,9 +12,11 @@ @@
 #ifndef NETWORK_CORE_PACKET_H
 #define NETWORK_CORE_PACKET_H
 #include "os_abstraction.h"
 #include "config.h"
 #include "core.h"
 #include "../../string_type.h"
 #include <functional>
 typedef uint16 PacketSize; ///< Size of the whole packet.
 typedef uint8  PacketType; ///< Identifier for the packet
@@ @@ -56,7 +58,7 @@ private: @@
 	NetworkSocketHandler *cs;
 public:
 	Packet(NetworkSocketHandler *cs);
+	Packet(NetworkSocketHandler *cs, size_t initial_read_size = sizeof(PacketSize));
 	Packet(PacketType type);
 	~Packet();
@@ @@ -83,6 +85,52 @@ public: @@
 	uint32 Recv_uint32();
 	uint64 Recv_uint64();
 	void   Recv_string(char *buffer, size_t size, StringValidationSettings settings = SVS_REPLACE_WITH_QUESTION_MARK);
 	size_t RemainingBytesToTransfer() const;
 	/**
 	 * Transfer data from the given function into the packet. It starts writing at the
 	 * position the last transfer stopped.
+	 *
 	 * Examples of functions that can be used to transfer data into a packet are TCP's
 	 * recv and UDP's recvfrom functions. They will directly write their data into the
 	 * packet without an intermediate buffer.
 	 * Examples of functions that can be used to transfer data from a packet are TCP's
 	 * send and UDP's sendto functions. They will directly read the data from the packet's
 	 * buffer without an intermediate buffer.
 	 * These are functions are special in a sense as even though the packet can send or
 	 * receive an amount of data, those functions can say they only processed a smaller
 	 * amount, so special handling is required to keep the position pointers correct.
 	 * Most of these transfer functions are in the form function(source, buffer, amount, ...),
 	 * so the template of this function will assume that as the base parameter order.
+	 *
 	 * This will attempt to write all the remaining bytes into the packet. It updates the
 	 * position based on how many bytes were actually written by the called transfer_function.
 	 * @param transfer_function The function to pass the buffer as second parameter and the
 	 *                          amount to read as third parameter. It returns the amount that
 	 *                          was read or -1 upon errors.
 	 * @param source            The first parameter of the transfer function.
 	 * @param args              The fourth and further parameters to the transfer function, if any.
 	 * @tparam A    The type for the amount to be passed, so it can be cast to the right type.
 	 * @tparam F    The type of the transfer_function.
 	 * @tparam S    The type of the source.
 	 * @tparam Args The types of the remaining arguments to the function.
 	 * @return The return value of the transfer_function.
 	 */
 	template <typename A = size_t, typename F, typename S, typename ... Args>
 	ssize_t TransferIn(F transfer_function, S source, Args&& ... args)
+	{
 		size_t amount = this->RemainingBytesToTransfer();
 		if (amount == 0) return 0;
 		assert(this->pos < this->buffer.size());
 		assert(this->pos + amount <= this->buffer.size());
 		/* Making buffer a char means casting a lot in the Recv/Send functions. */
 		char *input_buffer = reinterpret_cast<char*>(this->buffer + this->pos);
 		ssize_t bytes = transfer_function(source, input_buffer, static_cast<A>(amount), std::forward<Args>(args)...);
 		if (bytes > 0) this->pos += bytes;
 		return bytes;
+	}
 };
 #endif /* NETWORK_CORE_PACKET_H */

src/network/core/tcp.cpp

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@@ @@ -156,9 +156,8 @@ Packet *NetworkTCPSocketHandler::Receive @@
 	/* Read packet size */
 	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);
 		while (p->RemainingBytesToTransfer() != 0) {
 			res = p->TransferIn<int>(recv, this->sock, 0);
 			if (res == -1) {
 				int err = GET_LAST_ERROR();
 				if (err != EWOULDBLOCK) {
@@ @@ -175,7 +174,6 @@ Packet *NetworkTCPSocketHandler::Receive @@
 				this->CloseConnection();
 				return nullptr;
+			}
 			p->pos += res;
+		}
 		/* Parse the size in the received packet and if not valid, close the connection. */
@@ @@ -186,8 +184,8 @@ Packet *NetworkTCPSocketHandler::Receive @@
+	}
 	/* Read rest of packet */
 	while (p->pos < p->size) {
 		res = recv(this->sock, (char*)p->buffer + p->pos, p->size - p->pos, 0);
 	while (p->RemainingBytesToTransfer() != 0) {
 		res = p->TransferIn<int>(recv, this->sock, 0);
 		if (res == -1) {
 			int err = GET_LAST_ERROR();
 			if (err != EWOULDBLOCK) {
@@ @@ -204,8 +202,6 @@ Packet *NetworkTCPSocketHandler::Receive @@
 			this->CloseConnection();
 			return nullptr;
+		}
 		p->pos += res;
+	}
 	/* Prepare for receiving a new packet */

src/network/core/udp.cpp

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@@ @@ -119,12 +119,12 @@ void NetworkUDPSocketHandler::ReceivePac @@
 			struct sockaddr_storage client_addr;
 			memset(&client_addr, 0, sizeof(client_addr));
 			Packet p(this);
+			Packet p(this, SEND_MTU);
 			socklen_t client_len = sizeof(client_addr);
 			/* Try to receive anything */
 			SetNonBlocking(s.second); // Some OSes seem to lose the non-blocking status of the socket
-			int nbytes = recvfrom(s.second, (char*)p.buffer, SEND_MTU, 0, (struct sockaddr *)&client_addr, &client_len);
+			ssize_t nbytes = p.TransferIn<int>(recvfrom, s.second, 0, (struct sockaddr *)&client_addr, &client_len);
 			/* Did we get the bytes for the base header of the packet? */
 			if (nbytes <= 0) break;    // No data, i.e. no packet

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