dcsctp: support socket handover in ReassemblyQueue

Bug: webrtc:13154
Change-Id: I816e51dcd923ba6440480de5d5df9012e4af9e5a
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/231958
Reviewed-by: Victor Boivie <boivie@webrtc.org>
Commit-Queue: Sergey Sukhanov <sergeysu@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#35002}

net/dcsctp/public/dcsctp_handover_state.h

@@ -34,6 +34,8 @@ struct DcSctpSocketHandoverState {
   struct Receive {
     bool seen_packet = false;
     uint32_t last_cumulative_acked_tsn = 0;
+    uint32_t last_assembled_tsn = 0;
+    uint32_t last_completed_deferred_reset_req_sn = 0;
     std::vector<OrderedStream> ordered_streams;
     std::vector<UnorderedStream> unordered_streams;
   };
@@ -46,7 +48,7 @@ enum class HandoverUnreadinessReason : uint32_t {
   kSendQueueNotEmpty = 2,
   kPendingStreamResetRequest = 4,
   kDataTrackerTsnBlocksPending = 8,
-  kReassemblyQueueNotEmpty = 16,
+  kPendingStreamReset = 16,
   kReassemblyQueueDeliveredTSNsGap = 32,
   kStreamResetDeferred = 64,
   kOrderedStreamHasUnassembledChunks = 128,
@@ -54,8 +56,7 @@ enum class HandoverUnreadinessReason : uint32_t {
   kRetransmissionQueueOutstandingData = 512,
   kRetransmissionQueueFastRecovery = 1024,
   kRetransmissionQueueNotEmpty = 2048,
-  kPendingStreamReset = 4096,
-  kMax = kPendingStreamReset,
+  kMax = kRetransmissionQueueNotEmpty,
 };
 
 // Return value of `DcSctpSocketInterface::GetHandoverReadiness`. Set of

net/dcsctp/rx/BUILD.gn

@@ -81,6 +81,7 @@ rtc_library("reassembly_queue") {
     "../packet:chunk",
     "../packet:data",
     "../packet:parameter",
+    "../public:socket",
     "../public:types",
   ]
   sources = [

net/dcsctp/rx/reassembly_queue.cc

@@ -34,20 +34,29 @@
 #include "rtc_base/logging.h"
 
 namespace dcsctp {
-ReassemblyQueue::ReassemblyQueue(absl::string_view log_prefix,
+ReassemblyQueue::ReassemblyQueue(
+    absl::string_view log_prefix,
     TSN peer_initial_tsn,
-                                 size_t max_size_bytes)
+    size_t max_size_bytes,
+    const DcSctpSocketHandoverState* handover_state)
     : log_prefix_(std::string(log_prefix) + "reasm: "),
       max_size_bytes_(max_size_bytes),
       watermark_bytes_(max_size_bytes * kHighWatermarkLimit),
-      last_assembled_tsn_watermark_(
-          tsn_unwrapper_.Unwrap(TSN(*peer_initial_tsn - 1))),
+      last_assembled_tsn_watermark_(tsn_unwrapper_.Unwrap(
+          handover_state ? TSN(handover_state->rx.last_assembled_tsn)
+                         : TSN(*peer_initial_tsn - 1))),
+      last_completed_reset_req_seq_nbr_(
+          handover_state
+              ? ReconfigRequestSN(
+                    handover_state->rx.last_completed_deferred_reset_req_sn)
+              : ReconfigRequestSN(0)),
       streams_(std::make_unique<TraditionalReassemblyStreams>(
           log_prefix_,
           [this](rtc::ArrayView<const UnwrappedTSN> tsns,
                  DcSctpMessage message) {
             AddReassembledMessage(tsns, std::move(message));
-          })) {}
+          },
+          handover_state)) {}
 
 void ReassemblyQueue::Add(TSN tsn, Data data) {
   RTC_DCHECK(IsConsistent());
@@ -242,4 +251,22 @@ bool ReassemblyQueue::IsConsistent() const {
   return (queued_bytes_ >= 0 && queued_bytes_ <= 2 * max_size_bytes_);
 }
 
+HandoverReadinessStatus ReassemblyQueue::GetHandoverReadiness() const {
+  HandoverReadinessStatus status = streams_->GetHandoverReadiness();
+  if (!delivered_tsns_.empty()) {
+    status.Add(HandoverUnreadinessReason::kReassemblyQueueDeliveredTSNsGap);
+  }
+  if (deferred_reset_streams_.has_value()) {
+    status.Add(HandoverUnreadinessReason::kStreamResetDeferred);
+  }
+  return status;
+}
+
+void ReassemblyQueue::AddHandoverState(DcSctpSocketHandoverState& state) {
+  state.rx.last_assembled_tsn = last_assembled_tsn_watermark_.Wrap().value();
+  state.rx.last_completed_deferred_reset_req_sn =
+      last_completed_reset_req_seq_nbr_.value();
+  streams_->AddHandoverState(state);
+}
+
 }  // namespace dcsctp

net/dcsctp/rx/reassembly_queue.h

@@ -27,6 +27,7 @@
 #include "net/dcsctp/packet/data.h"
 #include "net/dcsctp/packet/parameter/outgoing_ssn_reset_request_parameter.h"
 #include "net/dcsctp/packet/parameter/reconfiguration_response_parameter.h"
+#include "net/dcsctp/public/dcsctp_handover_state.h"
 #include "net/dcsctp/public/dcsctp_message.h"
 #include "net/dcsctp/rx/reassembly_streams.h"
 
@@ -70,7 +71,8 @@ class ReassemblyQueue {
 
   ReassemblyQueue(absl::string_view log_prefix,
                   TSN peer_initial_tsn,
-                  size_t max_size_bytes);
+                  size_t max_size_bytes,
+                  const DcSctpSocketHandoverState* handover_state = nullptr);
 
   // Adds a data chunk to the queue, with a `tsn` and other parameters in
   // `data`.
@@ -118,6 +120,10 @@ class ReassemblyQueue {
   // Returns the watermark limit, in bytes.
   size_t watermark_bytes() const { return watermark_bytes_; }
 
+  HandoverReadinessStatus GetHandoverReadiness() const;
+
+  void AddHandoverState(DcSctpSocketHandoverState& state);
+
  private:
   bool IsConsistent() const;
   void AddReassembledMessage(rtc::ArrayView<const UnwrappedTSN> tsns,
@@ -150,7 +156,7 @@ class ReassemblyQueue {
 
   // Contains the last request sequence number of the
   // OutgoingSSNResetRequestParameter that was performed.
-  ReconfigRequestSN last_completed_reset_req_seq_nbr_ = ReconfigRequestSN(0);
+  ReconfigRequestSN last_completed_reset_req_seq_nbr_;
 
   // The number of "payload bytes" that are in this queue, in total.
   size_t queued_bytes_ = 0;

net/dcsctp/rx/reassembly_queue_test.cc

@@ -31,6 +31,7 @@
 namespace dcsctp {
 namespace {
 using ::testing::ElementsAre;
+using ::testing::SizeIs;
 
 // The default maximum size of the Reassembly Queue.
 static constexpr size_t kBufferSize = 10000;
@@ -294,5 +295,96 @@ TEST_F(ReassemblyQueueTest, ShouldntDeliverBeforeForwardedTsn) {
   EXPECT_FALSE(reasm.HasMessages());
 }
 
+TEST_F(ReassemblyQueueTest, NotReadyForHandoverWhenDeliveredTsnsHaveGap) {
+  ReassemblyQueue reasm("log: ", TSN(10), kBufferSize);
+  reasm.Add(TSN(10), gen_.Unordered({1, 2, 3, 4}, "B"));
+  EXPECT_FALSE(reasm.HasMessages());
+
+  reasm.Add(TSN(12), gen_.Unordered({1, 2, 3, 4}, "BE"));
+  EXPECT_TRUE(reasm.HasMessages());
+  EXPECT_EQ(
+      reasm.GetHandoverReadiness(),
+      HandoverReadinessStatus()
+          .Add(HandoverUnreadinessReason::kReassemblyQueueDeliveredTSNsGap)
+          .Add(
+              HandoverUnreadinessReason::kUnorderedStreamHasUnassembledChunks));
+
+  EXPECT_THAT(reasm.FlushMessages(),
+              ElementsAre(SctpMessageIs(kStreamID, kPPID, kShortPayload)));
+  EXPECT_EQ(
+      reasm.GetHandoverReadiness(),
+      HandoverReadinessStatus()
+          .Add(HandoverUnreadinessReason::kReassemblyQueueDeliveredTSNsGap)
+          .Add(
+              HandoverUnreadinessReason::kUnorderedStreamHasUnassembledChunks));
+
+  reasm.Handle(ForwardTsnChunk(TSN(13), {}));
+  EXPECT_EQ(reasm.GetHandoverReadiness(), HandoverReadinessStatus());
+}
+
+TEST_F(ReassemblyQueueTest, NotReadyForHandoverWhenResetStreamIsDeferred) {
+  ReassemblyQueue reasm("log: ", TSN(10), kBufferSize);
+  DataGeneratorOptions opts;
+  opts.message_id = MID(0);
+  reasm.Add(TSN(10), gen_.Ordered({1, 2, 3, 4}, "BE", opts));
+  opts.message_id = MID(1);
+  reasm.Add(TSN(11), gen_.Ordered({1, 2, 3, 4}, "BE", opts));
+  EXPECT_THAT(reasm.FlushMessages(), SizeIs(2));
+
+  reasm.ResetStreams(
+      OutgoingSSNResetRequestParameter(
+          ReconfigRequestSN(10), ReconfigRequestSN(3), TSN(13), {StreamID(1)}),
+      TSN(11));
+  EXPECT_EQ(reasm.GetHandoverReadiness(),
+            HandoverReadinessStatus().Add(
+                HandoverUnreadinessReason::kStreamResetDeferred));
+
+  opts.message_id = MID(3);
+  opts.ppid = PPID(3);
+  reasm.Add(TSN(13), gen_.Ordered({1, 2, 3, 4}, "BE", opts));
+  reasm.MaybeResetStreamsDeferred(TSN(11));
+
+  opts.message_id = MID(2);
+  opts.ppid = PPID(2);
+  reasm.Add(TSN(13), gen_.Ordered({1, 2, 3, 4}, "BE", opts));
+  reasm.MaybeResetStreamsDeferred(TSN(15));
+  EXPECT_EQ(reasm.GetHandoverReadiness(),
+            HandoverReadinessStatus().Add(
+                HandoverUnreadinessReason::kReassemblyQueueDeliveredTSNsGap));
+
+  EXPECT_THAT(reasm.FlushMessages(), SizeIs(2));
+  EXPECT_EQ(reasm.GetHandoverReadiness(),
+            HandoverReadinessStatus().Add(
+                HandoverUnreadinessReason::kReassemblyQueueDeliveredTSNsGap));
+
+  reasm.Handle(ForwardTsnChunk(TSN(15), {}));
+  EXPECT_EQ(reasm.GetHandoverReadiness(), HandoverReadinessStatus());
+}
+
+TEST_F(ReassemblyQueueTest, HandoverInInitialState) {
+  ReassemblyQueue reasm1("log: ", TSN(10), kBufferSize);
+
+  EXPECT_EQ(reasm1.GetHandoverReadiness(), HandoverReadinessStatus());
+  DcSctpSocketHandoverState state;
+  reasm1.AddHandoverState(state);
+  ReassemblyQueue reasm2("log: ", TSN(100), kBufferSize, &state);
+
+  reasm2.Add(TSN(10), gen_.Ordered({1, 2, 3, 4}, "BE"));
+  EXPECT_THAT(reasm2.FlushMessages(), SizeIs(1));
+}
+
+TEST_F(ReassemblyQueueTest, HandoverAfterHavingAssembedOneMessage) {
+  ReassemblyQueue reasm1("log: ", TSN(10), kBufferSize);
+  reasm1.Add(TSN(10), gen_.Ordered({1, 2, 3, 4}, "BE"));
+  EXPECT_THAT(reasm1.FlushMessages(), SizeIs(1));
+
+  EXPECT_EQ(reasm1.GetHandoverReadiness(), HandoverReadinessStatus());
+  DcSctpSocketHandoverState state;
+  reasm1.AddHandoverState(state);
+  ReassemblyQueue reasm2("log: ", TSN(100), kBufferSize, &state);
+
+  reasm2.Add(TSN(11), gen_.Ordered({1, 2, 3, 4}, "BE"));
+  EXPECT_THAT(reasm2.FlushMessages(), SizeIs(1));
+}
 }  // namespace
 }  // namespace dcsctp