dcsctp: Add Context

In the Socket module, there are a few (two, to be exact right now, but
the goal is to have even more) separate "handlers" that are responsible
for a feature set. These handlers must have an API to interact with
the rest of the socket - and this is the API.

Mocks are also added.

Bug: webrtc:12614
Change-Id: If19b43bf99a784bba3a42467d0ed3abdd8b4c62c
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/214128
Commit-Queue: Victor Boivie <boivie@webrtc.org>
Reviewed-by: Tommi <tommi@webrtc.org>
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#33826}

net/dcsctp/socket/BUILD.gn

@@ -0,0 +1,40 @@
+# Copyright (c) 2021 The WebRTC project authors. All Rights Reserved.
+#
+# Use of this source code is governed by a BSD-style license
+# that can be found in the LICENSE file in the root of the source
+# tree. An additional intellectual property rights grant can be found
+# in the file PATENTS.  All contributing project authors may
+# be found in the AUTHORS file in the root of the source tree.
+
+import("../../../webrtc.gni")
+
+rtc_source_set("context") {
+  sources = [ "context.h" ]
+  deps = [
+    "../common:internal_types",
+    "../packet:sctp_packet",
+    "../public:socket",
+    "../public:types",
+  ]
+}
+
+if (rtc_include_tests) {
+  rtc_source_set("mock_callbacks") {
+    testonly = true
+    sources = [ "mock_dcsctp_socket_callbacks.h" ]
+    deps = [ "../public:socket" ]
+  }
+
+  rtc_source_set("mock_context") {
+    testonly = true
+    sources = [ "mock_context.h" ]
+    deps = [
+      ":context",
+      ":mock_callbacks",
+      "../common:internal_types",
+      "../packet:sctp_packet",
+      "../public:socket",
+      "../public:types",
+    ]
+  }
+}

net/dcsctp/socket/context.h

@@ -0,0 +1,66 @@
+/*
+ *  Copyright (c) 2021 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+#ifndef NET_DCSCTP_SOCKET_CONTEXT_H_
+#define NET_DCSCTP_SOCKET_CONTEXT_H_
+
+#include <cstdint>
+
+#include "absl/strings/string_view.h"
+#include "net/dcsctp/common/internal_types.h"
+#include "net/dcsctp/packet/sctp_packet.h"
+#include "net/dcsctp/public/dcsctp_socket.h"
+#include "net/dcsctp/public/types.h"
+
+namespace dcsctp {
+
+// A set of helper methods used by handlers to e.g. send packets.
+//
+// Implemented by the TransmissionControlBlock.
+class Context {
+ public:
+  virtual ~Context() = default;
+
+  // Indicates if a connection has been established.
+  virtual bool is_connection_established() const = 0;
+
+  // Returns this side's initial TSN value.
+  virtual TSN my_initial_tsn() const = 0;
+
+  // Returns the peer's initial TSN value.
+  virtual TSN peer_initial_tsn() const = 0;
+
+  // Returns the socket callbacks.
+  virtual DcSctpSocketCallbacks& callbacks() const = 0;
+
+  // Observes a measured RTT value, in milliseconds.
+  virtual void ObserveRTT(DurationMs rtt_ms) = 0;
+
+  // Returns the current Retransmission Timeout (rto) value, in milliseconds.
+  virtual DurationMs current_rto() const = 0;
+
+  // Increments the transmission error counter, given a human readable reason.
+  virtual bool IncrementTxErrorCounter(absl::string_view reason) = 0;
+
+  // Clears the transmission error counter.
+  virtual void ClearTxErrorCounter() = 0;
+
+  // Returns true if there have been too many retransmission errors.
+  virtual bool HasTooManyTxErrors() const = 0;
+
+  // Returns a PacketBuilder, filled in with the correct verification tag.
+  virtual SctpPacket::Builder PacketBuilder() const = 0;
+
+  // Builds the packet from `builder` and sends it.
+  virtual void Send(SctpPacket::Builder& builder) = 0;
+};
+
+}  // namespace dcsctp
+
+#endif  // NET_DCSCTP_SOCKET_CONTEXT_H_

net/dcsctp/socket/mock_context.h

@@ -0,0 +1,72 @@
+/*
+ *  Copyright (c) 2021 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+#ifndef NET_DCSCTP_SOCKET_MOCK_CONTEXT_H_
+#define NET_DCSCTP_SOCKET_MOCK_CONTEXT_H_
+
+#include <cstdint>
+
+#include "absl/strings/string_view.h"
+#include "absl/types/optional.h"
+#include "net/dcsctp/packet/sctp_packet.h"
+#include "net/dcsctp/public/dcsctp_options.h"
+#include "net/dcsctp/public/dcsctp_socket.h"
+#include "net/dcsctp/socket/context.h"
+#include "net/dcsctp/socket/mock_dcsctp_socket_callbacks.h"
+#include "test/gmock.h"
+
+namespace dcsctp {
+
+class MockContext : public Context {
+ public:
+  static constexpr TSN MyInitialTsn() { return TSN(990); }
+  static constexpr TSN PeerInitialTsn() { return TSN(10); }
+  static constexpr VerificationTag PeerVerificationTag() {
+    return VerificationTag(0x01234567);
+  }
+
+  explicit MockContext(MockDcSctpSocketCallbacks* callbacks)
+      : callbacks_(*callbacks) {
+    ON_CALL(*this, is_connection_established)
+        .WillByDefault(testing::Return(true));
+    ON_CALL(*this, my_initial_tsn)
+        .WillByDefault(testing::Return(MyInitialTsn()));
+    ON_CALL(*this, peer_initial_tsn)
+        .WillByDefault(testing::Return(PeerInitialTsn()));
+    ON_CALL(*this, callbacks).WillByDefault(testing::ReturnRef(callbacks_));
+    ON_CALL(*this, current_rto).WillByDefault(testing::Return(DurationMs(123)));
+    ON_CALL(*this, Send).WillByDefault([this](SctpPacket::Builder& builder) {
+      callbacks_.SendPacket(builder.Build());
+    });
+  }
+
+  MOCK_METHOD(bool, is_connection_established, (), (const, override));
+  MOCK_METHOD(TSN, my_initial_tsn, (), (const, override));
+  MOCK_METHOD(TSN, peer_initial_tsn, (), (const, override));
+  MOCK_METHOD(DcSctpSocketCallbacks&, callbacks, (), (const, override));
+
+  MOCK_METHOD(void, ObserveRTT, (DurationMs rtt_ms), (override));
+  MOCK_METHOD(DurationMs, current_rto, (), (const, override));
+  MOCK_METHOD(bool,
+              IncrementTxErrorCounter,
+              (absl::string_view reason),
+              (override));
+  MOCK_METHOD(void, ClearTxErrorCounter, (), (override));
+  MOCK_METHOD(bool, HasTooManyTxErrors, (), (const, override));
+  SctpPacket::Builder PacketBuilder() const override {
+    return SctpPacket::Builder(PeerVerificationTag(), options_);
+  }
+  MOCK_METHOD(void, Send, (SctpPacket::Builder & builder), (override));
+
+  DcSctpOptions options_;
+  MockDcSctpSocketCallbacks& callbacks_;
+};
+}  // namespace dcsctp
+
+#endif  // NET_DCSCTP_SOCKET_MOCK_CONTEXT_H_

net/dcsctp/socket/mock_dcsctp_socket_callbacks.h

@@ -0,0 +1,152 @@
+/*
+ *  Copyright (c) 2021 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+#ifndef NET_DCSCTP_SOCKET_MOCK_DCSCTP_SOCKET_CALLBACKS_H_
+#define NET_DCSCTP_SOCKET_MOCK_DCSCTP_SOCKET_CALLBACKS_H_
+
+#include <cstdint>
+#include <deque>
+#include <memory>
+#include <utility>
+#include <vector>
+
+#include "absl/strings/string_view.h"
+#include "absl/types/optional.h"
+#include "api/array_view.h"
+#include "net/dcsctp/public/dcsctp_message.h"
+#include "net/dcsctp/public/dcsctp_socket.h"
+#include "net/dcsctp/public/timeout.h"
+#include "net/dcsctp/public/types.h"
+#include "net/dcsctp/timer/fake_timeout.h"
+#include "rtc_base/logging.h"
+#include "rtc_base/random.h"
+#include "test/gmock.h"
+
+namespace dcsctp {
+
+namespace internal {
+// It can be argued if a mocked random number generator should be deterministic
+// or if it should be have as a "real" random number generator. In this
+// implementation, each instantiation of `MockDcSctpSocketCallbacks` will have
+// their `GetRandomInt` return different sequences, but each instantiation will
+// always generate the same sequence of random numbers. This to make it easier
+// to compare logs from tests, but still to let e.g. two different sockets (used
+// in the same test) get different random numbers, so that they don't start e.g.
+// on the same sequence number. While that isn't an issue in the protocol, it
+// just makes debugging harder as the two sockets would look exactly the same.
+//
+// In a real implementation of `DcSctpSocketCallbacks` the random number
+// generator backing `GetRandomInt` should be seeded externally and correctly.
+inline int GetUniqueSeed() {
+  static int seed = 0;
+  return ++seed;
+}
+}  // namespace internal
+
+class MockDcSctpSocketCallbacks : public DcSctpSocketCallbacks {
+ public:
+  MockDcSctpSocketCallbacks()
+      : random_(internal::GetUniqueSeed()),
+        timeout_manager_([this]() { return now_; }) {
+    ON_CALL(*this, SendPacket)
+        .WillByDefault([this](rtc::ArrayView<const uint8_t> data) {
+          sent_packets_.emplace_back(
+              std::vector<uint8_t>(data.begin(), data.end()));
+        });
+    ON_CALL(*this, OnMessageReceived)
+        .WillByDefault([this](DcSctpMessage message) {
+          received_messages_.emplace_back(std::move(message));
+        });
+
+    ON_CALL(*this, OnError)
+        .WillByDefault([](ErrorKind error, absl::string_view message) {
+          RTC_LOG(LS_WARNING)
+              << "Socket error: " << ToString(error) << "; " << message;
+        });
+  }
+  MOCK_METHOD(void,
+              SendPacket,
+              (rtc::ArrayView<const uint8_t> data),
+              (override));
+
+  std::unique_ptr<Timeout> CreateTimeout() override {
+    return timeout_manager_.CreateTimeout();
+  }
+
+  TimeMs TimeMillis() override { return now_; }
+
+  uint32_t GetRandomInt(uint32_t low, uint32_t high) override {
+    return random_.Rand(low, high);
+  }
+  MOCK_METHOD(void, NotifyOutgoingMessageBufferEmpty, (), (override));
+
+  MOCK_METHOD(void, OnMessageReceived, (DcSctpMessage message), (override));
+  MOCK_METHOD(void,
+              OnError,
+              (ErrorKind error, absl::string_view message),
+              (override));
+  MOCK_METHOD(void,
+              OnAborted,
+              (ErrorKind error, absl::string_view message),
+              (override));
+  MOCK_METHOD(void, OnConnected, (), (override));
+  MOCK_METHOD(void, OnClosed, (), (override));
+  MOCK_METHOD(void, OnConnectionRestarted, (), (override));
+  MOCK_METHOD(void,
+              OnStreamsResetFailed,
+              (rtc::ArrayView<const StreamID> outgoing_streams,
+               absl::string_view reason),
+              (override));
+  MOCK_METHOD(void,
+              OnStreamsResetPerformed,
+              (rtc::ArrayView<const StreamID> outgoing_streams),
+              (override));
+  MOCK_METHOD(void,
+              OnIncomingStreamsReset,
+              (rtc::ArrayView<const StreamID> incoming_streams),
+              (override));
+  MOCK_METHOD(void,
+              OnSentMessageExpired,
+              (StreamID stream_id, PPID ppid, bool unsent),
+              (override));
+
+  bool HasPacket() const { return !sent_packets_.empty(); }
+
+  std::vector<uint8_t> ConsumeSentPacket() {
+    if (sent_packets_.empty()) {
+      return {};
+    }
+    std::vector<uint8_t> ret = std::move(sent_packets_.front());
+    sent_packets_.pop_front();
+    return ret;
+  }
+  absl::optional<DcSctpMessage> ConsumeReceivedMessage() {
+    if (received_messages_.empty()) {
+      return absl::nullopt;
+    }
+    DcSctpMessage ret = std::move(received_messages_.front());
+    received_messages_.pop_front();
+    return ret;
+  }
+
+  void AdvanceTime(DurationMs duration_ms) { now_ = now_ + duration_ms; }
+  void SetTime(TimeMs now) { now_ = now; }
+
+  std::vector<TimeoutID> RunTimers() { return timeout_manager_.RunTimers(); }
+
+ private:
+  TimeMs now_ = TimeMs(0);
+  webrtc::Random random_;
+  FakeTimeoutManager timeout_manager_;
+  std::deque<std::vector<uint8_t>> sent_packets_;
+  std::deque<DcSctpMessage> received_messages_;
+};
+}  // namespace dcsctp
+
+#endif  // NET_DCSCTP_SOCKET_MOCK_DCSCTP_SOCKET_CALLBACKS_H_