Implement FETCH streams (#8)

Summary:
Pull Request resolved: #8

Adds support to MoQFramer, MoQCodec and MoQSession to send and receive fetch streams

Reviewed By: sharmafb

Differential Revision: D65532676

fbshipit-source-id: a667a677c1a9f3af98e9681e508769cf3df050c9

moxygen/MoQCodec.cpp

@@ -128,7 +128,10 @@ void MoQObjectStreamCodec::onIngress(
           case StreamType::STREAM_HEADER_SUBGROUP:
             parseState_ = ParseState::OBJECT_STREAM;
             break;
-          //  CONTROL doesn't have a wire type yet.
+          case StreamType::FETCH_HEADER:
+            parseState_ = ParseState::FETCH_HEADER;
+            break;
+            //  CONTROL doesn't have a wire type yet.
           default:
             XLOG(DBG4) << "Stream not allowed: 0x" << std::setfill('0')
                        << std::setw(sizeof(uint64_t) * 2) << std::hex
@@ -154,6 +157,19 @@ void MoQObjectStreamCodec::onIngress(
         }
         break;
       }
+      case ParseState::FETCH_HEADER: {
+        auto newCursor = cursor;
+        auto res = parseFetchHeader(newCursor);
+        if (res.hasError()) {
+          XLOG(DBG6) << __func__ << " " << uint32_t(res.error());
+          connError_ = res.error();
+          break;
+        }
+        curObjectHeader_.trackIdentifier = SubscribeID(res.value());
+        parseState_ = ParseState::MULTI_OBJECT_HEADER;
+        cursor = newCursor;
+        break;
+      }
       case ParseState::OBJECT_STREAM: {
         auto newCursor = cursor;
         auto res = parseStreamHeader(newCursor, streamType_);

moxygen/MoQCodec.h

@@ -141,6 +141,7 @@ class MoQObjectStreamCodec : public MoQCodec {
    public:
     ~ObjectCallback() override = default;
 
+    virtual void onFetchHeader(uint64_t subscribeID) = 0;
     virtual void onObjectHeader(ObjectHeader objectHeader) = 0;
 
     virtual void onObjectPayload(
@@ -168,6 +169,7 @@ class MoQObjectStreamCodec : public MoQCodec {
     STREAM_HEADER_TYPE,
     DATAGRAM,
     OBJECT_STREAM,
+    FETCH_HEADER,
     MULTI_OBJECT_HEADER,
     OBJECT_PAYLOAD,
     // OBJECT_PAYLOAD_NO_LENGTH

moxygen/MoQFramer.cpp

@@ -188,6 +188,15 @@ folly::Expected<ServerSetup, ErrorCode> parseServerSetup(
   return serverSetup;
 }
 
+folly::Expected<uint64_t, ErrorCode> parseFetchHeader(
+    folly::io::Cursor& cursor) noexcept {
+  auto subscribeID = quic::decodeQuicInteger(cursor);
+  if (!subscribeID) {
+    return folly::makeUnexpected(ErrorCode::PARSE_UNDERFLOW);
+  }
+  return subscribeID->first;
+}
+
 folly::Expected<ObjectHeader, ErrorCode> parseObjectHeader(
     folly::io::Cursor& cursor,
     size_t length) noexcept {
@@ -287,10 +296,13 @@ folly::Expected<ObjectHeader, ErrorCode> parseMultiObjectHeader(
     const ObjectHeader& headerTemplate) noexcept {
   DCHECK(
       streamType == StreamType::STREAM_HEADER_TRACK ||
-      streamType == StreamType::STREAM_HEADER_SUBGROUP);
+      streamType == StreamType::STREAM_HEADER_SUBGROUP ||
+      streamType == StreamType::FETCH_HEADER);
+  // TODO get rid of this
   auto length = cursor.totalLength();
   ObjectHeader objectHeader = headerTemplate;
-  if (streamType == StreamType::STREAM_HEADER_TRACK) {
+  if (streamType == StreamType::STREAM_HEADER_TRACK ||
+      streamType == StreamType::FETCH_HEADER) {
     auto group = quic::decodeQuicInteger(cursor, length);
     if (!group) {
       return folly::makeUnexpected(ErrorCode::PARSE_UNDERFLOW);
@@ -301,12 +313,28 @@ folly::Expected<ObjectHeader, ErrorCode> parseMultiObjectHeader(
   } else {
     objectHeader.forwardPreference = ForwardPreference::Subgroup;
   }
+  if (streamType == StreamType::FETCH_HEADER) {
+    objectHeader.forwardPreference = ForwardPreference::Fetch;
+    auto subgroup = quic::decodeQuicInteger(cursor, length);
+    if (!subgroup) {
+      return folly::makeUnexpected(ErrorCode::PARSE_UNDERFLOW);
+    }
+    length -= subgroup->second;
+    objectHeader.subgroup = subgroup->first;
+  }
   auto id = quic::decodeQuicInteger(cursor, length);
   if (!id) {
     return folly::makeUnexpected(ErrorCode::PARSE_UNDERFLOW);
   }
   length -= id->second;
   objectHeader.id = id->first;
+  if (streamType == StreamType::FETCH_HEADER) {
+    if (length < 2) {
+      return folly::makeUnexpected(ErrorCode::PARSE_UNDERFLOW);
+    }
+    objectHeader.priority = cursor.readBE<uint8_t>();
+    length--;
+  }
   auto payloadLength = quic::decodeQuicInteger(cursor, length);
   if (!payloadLength) {
     return folly::makeUnexpected(ErrorCode::PARSE_UNDERFLOW);
@@ -1153,6 +1181,9 @@ WriteResult writeStreamHeader(
         folly::to_underlying(StreamType::STREAM_HEADER_SUBGROUP),
         size,
         error);
+  } else if (objectHeader.forwardPreference == ForwardPreference::Fetch) {
+    writeVarint(
+        writeBuf, folly::to_underlying(StreamType::FETCH_HEADER), size, error);
   } else {
     LOG(FATAL) << "Unsupported forward preference to stream header";
   }
@@ -1161,8 +1192,10 @@ WriteResult writeStreamHeader(
     writeVarint(writeBuf, objectHeader.group, size, error);
     writeVarint(writeBuf, objectHeader.subgroup, size, error);
   }
-  writeBuf.append(&objectHeader.priority, 1);
-  size += 1;
+  if (objectHeader.forwardPreference != ForwardPreference::Fetch) {
+    writeBuf.append(&objectHeader.priority, 1);
+    size += 1;
+  }
   if (error) {
     return folly::makeUnexpected(quic::TransportErrorCode::INTERNAL_ERROR);
   }
@@ -1199,12 +1232,16 @@ WriteResult writeObject(
   if (objectHeader.forwardPreference != ForwardPreference::Subgroup) {
     writeVarint(writeBuf, objectHeader.group, size, error);
   }
+  if (objectHeader.forwardPreference == ForwardPreference::Fetch) {
+    writeVarint(writeBuf, objectHeader.subgroup, size, error);
+  }
   writeVarint(writeBuf, objectHeader.id, size, error);
   CHECK(
       objectHeader.status != ObjectStatus::NORMAL ||
       (objectHeader.length && *objectHeader.length > 0))
       << "Normal objects require non-zero length";
-  if (objectHeader.forwardPreference == ForwardPreference::Datagram) {
+  if (objectHeader.forwardPreference == ForwardPreference::Datagram ||
+      objectHeader.forwardPreference == ForwardPreference::Fetch) {
     writeBuf.append(&objectHeader.priority, 1);
     size += 1;
   }

moxygen/MoQFramer.h

@@ -112,6 +112,7 @@ enum class StreamType : uint64_t {
   OBJECT_DATAGRAM = 1,
   STREAM_HEADER_TRACK = 0x2,
   STREAM_HEADER_SUBGROUP = 0x4,
+  FETCH_HEADER = 0x5,
   CONTROL = 100000000
 };
 
@@ -148,7 +149,7 @@ constexpr uint64_t kVersionDraft06_exp =
 constexpr uint64_t kVersionDraft07_exp = 0xff070001; // Draft 7 FETCH support
 constexpr uint64_t kVersionDraft07_exp2 =
     0xff070002; // Draft 7 FETCH + removal of Subscribe ID on objects
-constexpr uint64_t kVersionDraftCurrent = kVersionDraft07_exp2;
+constexpr uint64_t kVersionDraftCurrent = kVersionDraft07;
 
 struct ClientSetup {
   std::vector<uint64_t> supportedVersions;
@@ -168,7 +169,7 @@ folly::Expected<ServerSetup, ErrorCode> parseServerSetup(
     folly::io::Cursor& cursor,
     size_t length) noexcept;
 
-enum class ForwardPreference : uint8_t { Track, Subgroup, Datagram };
+enum class ForwardPreference : uint8_t { Track, Subgroup, Datagram, Fetch };
 
 enum class ObjectStatus : uint64_t {
   NORMAL = 0,
@@ -264,6 +265,9 @@ folly::Expected<ObjectHeader, ErrorCode> parseObjectHeader(
     folly::io::Cursor& cursor,
     size_t length) noexcept;
 
+folly::Expected<uint64_t, ErrorCode> parseFetchHeader(
+    folly::io::Cursor& cursor) noexcept;
+
 folly::Expected<ObjectHeader, ErrorCode> parseStreamHeader(
     folly::io::Cursor& cursor,
     StreamType streamType) noexcept;

moxygen/MoQServer.cpp

@@ -92,18 +92,6 @@ void MoQServer::ControlVisitor::operator()(Fetch fetch) const {
   XLOG(INFO) << "Fetch id=" << fetch.subscribeID;
 }
 
-void MoQServer::ControlVisitor::operator()(FetchCancel fetchCancel) const {
-  XLOG(INFO) << "FetchCancel id=" << fetchCancel.subscribeID;
-}
-
-void MoQServer::ControlVisitor::operator()(FetchOk fetchOk) const {
-  XLOG(INFO) << "FetchOk id=" << fetchOk.subscribeID;
-}
-
-void MoQServer::ControlVisitor::operator()(FetchError fetchError) const {
-  XLOG(INFO) << "FetchError id=" << fetchError.subscribeID;
-}
-
 void MoQServer::ControlVisitor::operator()(SubscribeDone subscribeDone) const {
   XLOG(INFO) << "SubscribeDone id=" << subscribeDone.subscribeID
              << " code=" << folly::to_underlying(subscribeDone.statusCode)

moxygen/MoQServer.h

@@ -39,9 +39,6 @@ class MoQServer : public MoQSession::ServerSetupCallback {
     void operator()(SubscribeRequest subscribeReq) const override;
     void operator()(SubscribeUpdate subscribeUpdate) const override;
     void operator()(Fetch fetch) const override;
-    void operator()(FetchCancel fetchCancel) const override;
-    void operator()(FetchOk fetchOk) const override;
-    void operator()(FetchError fetchError) const override;
     void operator()(Unannounce unannounce) const override;
     void operator()(AnnounceCancel announceCancel) const override;
     void operator()(SubscribeAnnounces subscribeAnnounces) const override;