[SCTP] Socket (part 2) (#1533)

Author: ibc

worker/fuzzer/src/RTC/SCTP/association/FuzzerStateCookie.cpp

@@ -22,8 +22,11 @@ void FuzzerRtcSctpStateCookie::Fuzz(const uint8_t* data, size_t len)
 
 		if (len < RTC::SCTP::StateCookie::StateCookieLength + 5)
 		{
-			Utils::Byte::Set4Bytes(clonedData, 0, RTC::SCTP::StateCookie::MagicValue1);
-			Utils::Byte::Set2Bytes(clonedData, 34, RTC::SCTP::StateCookie::MagicValue2);
+			Utils::Byte::Set4Bytes(clonedData, 0, RTC::SCTP::StateCookie::Magic1);
+			Utils::Byte::Set2Bytes(
+			  clonedData,
+			  RTC::SCTP::StateCookie::NegotiatedCapabilitiesOffset,
+			  RTC::SCTP::StateCookie::Magic2);
 		}
 	}
 
@@ -36,33 +39,33 @@ void FuzzerRtcSctpStateCookie::Fuzz(const uint8_t* data, size_t len)
 		return;
 	}
 
-	stateCookie->GetMyVerificationTag();
-	stateCookie->GetPeerVerificationTag();
-	stateCookie->GetMyInitialTsn();
-	stateCookie->GetPeerInitialTsn();
-	stateCookie->GetMyAdvertisedReceiverWindowCredit();
+	stateCookie->GetLocalVerificationTag();
+	stateCookie->GetRemoteVerificationTag();
+	stateCookie->GetLocalInitialTsn();
+	stateCookie->GetRemoteInitialTsn();
+	stateCookie->GetRemoteAdvertisedReceiverWindowCredit();
 	stateCookie->GetTieTag();
 	stateCookie->GetNegotiatedCapabilities();
 
 	stateCookie->Serialize(StateCookieSerializeBuffer, len);
 
-	stateCookie->GetMyVerificationTag();
-	stateCookie->GetPeerVerificationTag();
-	stateCookie->GetMyInitialTsn();
-	stateCookie->GetPeerInitialTsn();
-	stateCookie->GetMyAdvertisedReceiverWindowCredit();
+	stateCookie->GetLocalVerificationTag();
+	stateCookie->GetRemoteVerificationTag();
+	stateCookie->GetLocalInitialTsn();
+	stateCookie->GetRemoteInitialTsn();
+	stateCookie->GetRemoteAdvertisedReceiverWindowCredit();
 	stateCookie->GetTieTag();
 	stateCookie->GetNegotiatedCapabilities();
 
 	auto* clonedStateCookie = stateCookie->Clone(StateCookieCloneBuffer, len);
 
 	delete stateCookie;
 
-	clonedStateCookie->GetMyVerificationTag();
-	clonedStateCookie->GetPeerVerificationTag();
-	clonedStateCookie->GetMyInitialTsn();
-	clonedStateCookie->GetPeerInitialTsn();
-	clonedStateCookie->GetMyAdvertisedReceiverWindowCredit();
+	clonedStateCookie->GetLocalVerificationTag();
+	clonedStateCookie->GetRemoteVerificationTag();
+	clonedStateCookie->GetLocalInitialTsn();
+	clonedStateCookie->GetRemoteInitialTsn();
+	clonedStateCookie->GetRemoteAdvertisedReceiverWindowCredit();
 	clonedStateCookie->GetTieTag();
 	clonedStateCookie->GetNegotiatedCapabilities();
 

worker/fuzzer/src/RTC/SCTP/packet/FuzzerPacket.cpp

@@ -36,7 +36,7 @@ void FuzzerRtcSctpPacket::Fuzz(const uint8_t* data, size_t len)
 	packet->GetChecksum();
 	packet->ValidateCRC32cChecksum();
 	packet->SetChecksum(999999);
-	packet->SetCRC32cChecksum();
+	packet->WriteCRC32cChecksum();
 	packet->ValidateCRC32cChecksum();
 	packet->HasChunks();
 	packet->GetChunksCount();
@@ -58,7 +58,7 @@ void FuzzerRtcSctpPacket::Fuzz(const uint8_t* data, size_t len)
 	clonedPacket->GetChecksum();
 	clonedPacket->ValidateCRC32cChecksum();
 	clonedPacket->SetChecksum(999999);
-	clonedPacket->SetCRC32cChecksum();
+	clonedPacket->WriteCRC32cChecksum();
 	clonedPacket->ValidateCRC32cChecksum();
 	clonedPacket->HasChunks();
 	clonedPacket->GetChunksCount();

worker/include/RTC/SCTP/TODO_SCTP.md

@@ -12,9 +12,3 @@ Here some notes about our future SCTP implementation.
 However, in step 4 `WebRtcTransport::OnDtlsTransportApplicationDataReceived()` should instead call `RTC::SCTP::Packet::parse()` and `Transport::ReceiveSctpPacket()` with a `SCTP::Packet` instance instead than `data` and `len`. In fact it should be named `Transport::ReceiveSctpPacket()` instead of the current `Transport::ReceiveSctpData()`.
 
 Same in `PipeTransport` and `PlainTransport`.
-
-## TODO
-
-- Try to remove all `friend class`.
-
-- In `HeartbeatChunk` the `HeartbeatInfoParameter` should be mandatory when parsing. Or should we add some `Validate()` method?

worker/include/RTC/SCTP/association/NegotiatedCapabilities.hpp

@@ -2,6 +2,10 @@
 #define MS_RTC_SCTP_NEGOTIATED_CAPABILITIES_HPP
 
 #include "common.hpp"
+#include "RTC/SCTP/association/SocketOptions.hpp"
+#include "RTC/SCTP/packet/chunks/InitAckChunk.hpp"
+#include "RTC/SCTP/packet/chunks/InitChunk.hpp"
+#include <variant> // std::variant, std::visit()
 
 namespace RTC
 {
@@ -14,6 +18,19 @@ namespace RTC
 		 */
 		struct NegotiatedCapabilities
 		{
+			using InitOrInitAckChunkVariant = std::variant<const InitChunk*, const InitAckChunk*>;
+
+			/**
+			 * Create a NegotiatedCapabilities struct. Intended to be used during
+			 * the SCTP association handshake flow.
+			 *
+			 * @remarks
+			 * Given `remoteChunk` must be an INIT or an INIT_ACK Chunk. Otherwise
+			 * it will fail in compilation time.
+			 */
+			static NegotiatedCapabilities Factory(
+			  SocketOptions socketOptions, InitOrInitAckChunkVariant remoteChunk);
+
 			/**
 			 * Negotiated maximum number of outbound streams (OS).
 			 */

worker/include/RTC/SCTP/association/Socket.hpp

@@ -2,9 +2,25 @@
 #define MS_RTC_SCTP_SOCKET_HPP
 
 #include "common.hpp"
-#include "RTC/Consts.hpp"
+#include "RTC/SCTP/association/NegotiatedCapabilities.hpp"
+#include "RTC/SCTP/association/SocketMetrics.hpp"
+#include "RTC/SCTP/association/SocketOptions.hpp"
 #include "RTC/SCTP/association/TransmissionControlBlock.hpp"
-#include "RTC/SCTP/packet/parameters/ZeroChecksumAcceptableParameter.hpp"
+#include "RTC/SCTP/packet/Chunk.hpp"
+#include "RTC/SCTP/packet/Packet.hpp"
+#include "RTC/SCTP/packet/chunks/AbortAssociationChunk.hpp"
+#include "RTC/SCTP/packet/chunks/DataChunk.hpp"
+#include "RTC/SCTP/packet/chunks/HeartbeatRequestChunk.hpp"
+#include "RTC/SCTP/packet/chunks/InitAckChunk.hpp"
+#include "RTC/SCTP/packet/chunks/InitChunk.hpp"
+#include "RTC/SCTP/packet/chunks/OperationErrorChunk.hpp"
+#include "RTC/SCTP/packet/chunks/SackChunk.hpp"
+#include "RTC/SCTP/packet/chunks/ShutdownAckChunk.hpp"
+#include "RTC/SCTP/packet/chunks/ShutdownCompleteChunk.hpp"
+#include "RTC/SCTP/packet/chunks/UnknownChunk.hpp"
+#include "handles/BackoffTimerHandle.hpp"
+#include <string>
+#include <string_view>
 
 namespace RTC
 {
@@ -16,82 +32,168 @@ namespace RTC
 		 *
 		 * It manages all Packet and Chunk dispatching and the connection flow.
 		 */
-		class Socket
+		class Socket : public BackoffTimerHandle::Listener
 		{
 		public:
-			struct SocketOptions
+			class Listener
 			{
-				/**
-				 * Signaled local port.
-				 */
-				uint16_t localPort{ 0 };
-				/**
-				 * Signaled destination port.
-				 */
-				uint16_t destinationPort{ 0 };
-				/**
-				 * Announced maximum number of outbound streams (OS).
-				 * NOTE: We use maximum value by default.
-				 */
-				uint16_t maxOutboundStreams{ 65535 };
-				/**
-				 * Announced maximum number of inbound streams (MIS).
-				 * NOTE: We use maximum value by default.
-				 */
-				uint16_t maxInboundStreams{ 65535 };
-				/**
-				 * Maximum received window buffer size. It must be larger than the
-				 * largest sized message we want to be able to receive.
-				 *
-				 * @remarks
-				 * Default value copied from dcSCTP library.
-				 */
-				uint32_t myAdvertisedReceiverWindowCredit{ 5 * 1024 * 1024 };
-				/**
-				 * Use Partial Reliability Extension.
-				 * @see RFC 3758.
-				 */
-				bool partialReliability{ false };
-				/**
-				 * Use Stream Schedulers and User Message Interleaving (I-DATA Chunks).
-				 * @see RFC 8260.
-				 */
-				bool messageInterleaving{ false };
-				/**
-				 * Alternate error detection method for Zero Checksum.
-				 *
-				 * @remarks
-				 * This feature is only enabled if both peers signal their wish to use
-				 * the same (non-zero) Zero Checksum Alternate Error Detection Method.
-				 *
-				 * @see RFC 9653.
-				 */
-				ZeroChecksumAcceptableParameter::AlternateErrorDetectionMethod zeroCheksumAlternateErrorDetectionMethod{
-					ZeroChecksumAcceptableParameter::AlternateErrorDetectionMethod::NONE
-				};
-				/**
-				 * Maximum size of a SCTP packet. It doesn't include any overhead of
-				 * DTLS, TURN, UDP or IP headers.
-				 */
-				size_t mtu{ RTC::Consts::MaxSafeMtuSizeForSctp };
+			public:
+				virtual ~Listener() = default;
+
+			public:
+				virtual void OnSocketSendSctpPacket(const Socket* socket, Packet* packet) const = 0;
+			};
+
+		public:
+			/**
+			 * SCTP association state.
+			 */
+			enum class State
+			{
+				CLOSED,
+				COOKIE_WAIT,
+				// NOTE: TCB is valid in these states:
+				COOKIE_ECHOED,
+				ESTABLISHED,
+				SHUTDOWN_PENDING,
+				SHUTDOWN_SENT,
+				SHUTDOWN_RECEIVED,
+				SHUTDOWN_ACK_SENT,
 			};
 
+			/**
+			 * Struct holding local verification tag and initial TSN between having
+			 * sent the INIT Chunk until the connection is established (there is no
+			 * TCB in between).
+			 *
+			 * @remarks
+			 * This is how dcSCTP does, despite RFC 9260 states that the TCB should
+			 * also be created when an INIT Chunk is sent.
+			 */
+			struct PreTransmissionControlBlock
+			{
+				uint32_t localVerificationTag{ 0 };
+				uint32_t localInitialTsn{ 0 };
+			};
+
+		public:
+			static constexpr std::string_view State2String(State state);
+
 		public:
-			explicit Socket(SocketOptions options);
+			explicit Socket(SocketOptions options, Listener* listener);
 
 			~Socket();
 
 			void Dump(int indentation = 0) const;
 
+			/**
+			 * Initiate the SCTP association with the remote peer. It sends an INIT
+			 * Chunk.
+			 *
+			 * @remarks
+			 * The Socket must be in Closed state.
+			 */
+			void Associate();
+
+			/**
+			 * Receive a Packet received from the peer.
+			 */
+			void ReceivePacket(const Packet* receivedPacket);
+
 		private:
+			void SetState(State state, const std::string& reason);
+
+			void AddCapabilitiesParametersToInitOrInitAckChunk(Chunk* chunk) const;
+
+			void CreateTransmissionControlBlock(
+			  uint32_t localVerificationTag,
+			  uint32_t remoteVerificationTag,
+			  uint32_t localInitialTsn,
+			  uint32_t remoteInitialTsn,
+			  uint32_t localAdvertisedReceiverWindowCredit,
+			  uint64_t tieTag,
+			  const NegotiatedCapabilities& negotiatedCapabilities);
+
+			Packet* CreatePacket() const;
+
+			Packet* CreatePacketWithVerificationTag(uint32_t verificationTag) const;
+
+			/**
+			 * Notify the parent about a Packet to be sent to the peer.
+			 *
+			 * This method also writes the Packet checksum field depending on the value
+			 * of `writeChecksum`. If it's explicitly set then it's honored. Otherwise
+			 * the checksum field is written based on whether Zero Checksum has been
+			 * negotiated or not.
+			 *
+			 * @remarks
+			 * This method does not delete the given `packet`. The caller must do it
+			 * after invoking this method.
+			 */
+			void SendPacket(Packet* packet, std::optional<bool> writeChecksum = std::nullopt);
+
 			void SendInitChunk();
 
+			void SendShutdownAckChunk();
+
+			bool ValidateReceivedPacket(const Packet* receivedPacket);
+
+			bool ProcessReceivedChunk(const Packet* receivedPacket, const Chunk* receivedChunk);
+
+			void ProcessReceivedDataChunk(const Packet* receivedPacket, const DataChunk* receivedDataChunk);
+
+			void ProcessReceivedInitChunk(const Packet* receivedPacket, const InitChunk* receivedInitChunk);
+
+			void ProcessReceivedInitAckChunk(
+			  const Packet* receivedPacket, const InitAckChunk* receivedInitAckChunk);
+
+			void ProcessReceivedSackChunk(const Packet* receivedPacket, const SackChunk* receivedSackChunk);
+
+			void ProcessReceivedHeartbeatRequestChunk(
+			  const Packet* receivedPacket, const HeartbeatRequestChunk* receivedHeartbeatRequestChunk);
+
+			bool ProcessReceivedUnknownChunk(
+			  const Packet* receivedPacket, const UnknownChunk* receivedUnknownChunk);
+
+			void OnT1InitTimer(uint64_t& baseTimeout, bool& stop);
+
+			void OnT1CookieTimer(uint64_t& baseTimeout, bool& stop);
+
+			void OnT2ShutdownTimer(uint64_t& baseTimeout, bool& stop);
+
+			template<typename... States>
+			void AssertState(States... expectedStates) const;
+
+			template<typename... States>
+			void AssertNotState(States... unexpectedStates) const;
+
+			void AssertHasTcb() const;
+
+			/* Pure virtual methods inherited from BackoffTimerHandle::Listener. */
+		public:
+			void OnTimer(BackoffTimerHandle* backoffTimer, uint64_t& baseTimeout, bool& stop) override;
+
 		private:
 			// Socket options given in th econstructor.
-			Socket::SocketOptions options;
+			const SocketOptions options;
+			// Listener.
+			const Listener* listener{ nullptr };
+			// SCTP association state.
+			State state{ State::CLOSED };
+			// Metrics.
+			SocketMetrics metrics{};
+			// To keep settings between sending of INIT Chunk and establishment of
+			// the connection.
+			PreTransmissionControlBlock preTcb;
 			// Once the SCTP association is established a Transmission Control Block
-			// is created (and also when we are the initiator of the association).
+			// is created.
 			std::unique_ptr<TransmissionControlBlock> tcb;
+			// T1-init timer.
+			const std::unique_ptr<BackoffTimerHandle> t1InitTimer;
+			// T1-cookie timer.
+			const std::unique_ptr<BackoffTimerHandle> t1CookieTimer;
+			// T2-shutdown timer.
+			const std::unique_ptr<BackoffTimerHandle> t2ShutdownTimer;
 		};
 	} // namespace SCTP
 } // namespace RTC