Add server support for responding with Welcome to a Hello.

doc/CHANNELING-API.txt

@@ -87,6 +87,16 @@ Sending vs receiving document data encapsulation
     A    : Session attestation token. Only available for incoming data
            created by other sessions (optional).
 
+Error returns
+
+  Calls providing an Iid which fail will receive an Error document with the
+  following format:
+
+    {
+        "Type": "Error",
+        "Code": "value_identifying_error",
+        "Message": "A description of the error condition"
+    }
 
 Special purpose documents for channling
 
@@ -151,8 +161,10 @@ Special purpose documents for channling
         }
     }
 
-    Hello document is to be send by the client after connection was
-    established.
+    Hello document is to be send by the client after connection was established.
+    If an Iid is provided, a Welcome document will be returned if joining the
+    room with the given Id succeeds. Otherwise an Error document with one of the
+    error codes listed below will be returned.
 
     Keys under Hello:
 
@@ -160,6 +172,28 @@ Special purpose documents for channling
       Ua      : User agent description (string).
       Id      : Room id. The default Room has the empty string Id ("") (string).
 
+    Error codes:
+
+      default_room_disabled : Joining the room "" is not allowed by this server.
+
+  Welcome
+
+    {
+        Type: "Welcome",
+        Welcome: {
+            Users: [
+            ],
+        }
+    }
+
+    Welcome is sent in reply to a successful Hello, and contains all data
+    needed to set up the initial room connection.
+
+    Keys under Welcome:
+
+      Users: Contains the user list for the room, see the description of
+             the Users document for more details.
+
 Peer connection documents
 
   Offer

src/app/spreed-webrtc-server/channeling.go

@@ -21,12 +21,23 @@
 
 package main
 
+type DataError struct {
+	Type    string
+	Code    string
+	Message string
+}
+
 type DataHello struct {
 	Version string
 	Ua      string
 	Id      string
 }
 
+type DataWelcome struct {
+	Type  string
+	Users []*DataSession
+}
+
 type DataOffer struct {
 	Type  string
 	To    string

src/app/spreed-webrtc-server/channelling_api.go

@@ -85,13 +85,21 @@ func (api *channellingAPI) OnIncoming(c ResponseSender, session *Session, msg *D
 			api.Broadcast(session, session.DataSessionLeft("soft"))
 		}
 
+		// NOTE(lcooper): Iid filtered for compatibility's sake.
+		// Evaluate sending unconditionally when supported by all clients.
 		if api.CanJoinRoom(msg.Hello.Id) {
 			session.Hello = true
 			session.Roomid = msg.Hello.Id
 			api.JoinRoom(session, c)
+			if msg.Iid != "" {
+				c.Reply(msg.Iid, &DataWelcome{Type: "Welcome", Users: api.RoomUsers(session)})
+			}
 			api.Broadcast(session, session.DataSessionJoined())
 		} else {
 			session.Hello = false
+			if msg.Iid != "" {
+				c.Reply(msg.Iid, &DataError{Type: "Error", Code: "default_room_disabled", Message: "The default room is not enabled"})
+			}
 		}
 	case "Offer":
 		// TODO(longsleep): Validate offer

src/app/spreed-webrtc-server/channelling_api_test.go

@@ -30,12 +30,18 @@ const (
 )
 
 type fakeClient struct {
+	replies map[string]interface{}
 }
 
 func (fake *fakeClient) Send(_ Buffer) {
 }
 
-func (fake *fakeClient) Reply(_ string, _ interface{}) {
+func (fake *fakeClient) Reply(iid string, msg interface{}) {
+	if fake.replies == nil {
+		fake.replies = make(map[string]interface{})
+	}
+
+	fake.replies[iid] = msg
 }
 
 type fakeRoomManager struct {
@@ -132,3 +138,51 @@ func Test_ChannellingAPI_OnIncoming_HelloMessage_DoesNotJoinIfNotPermitted(t *te
 		t.Fatalf("Expected no broadcasts, but got %d", broadcastCount)
 	}
 }
+
+func Test_ChannellingAPI_OnIncoming_HelloMessageWithAnIid_RespondsWithAWelcome(t *testing.T) {
+	iid := "foo"
+	api, client, session, roomManager := NewTestChannellingAPI()
+	roomManager.roomUsers = []*DataSession{&DataSession{}}
+
+	api.OnIncoming(client, session, &DataIncoming{Type: "Hello", Iid: iid, Hello: &DataHello{}})
+
+	msg, ok := client.replies[iid]
+	if !ok {
+		t.Fatalf("No response received for Iid %v", iid)
+	}
+
+	welcome, ok := msg.(*DataWelcome)
+	if !ok {
+		t.Fatalf("Expected response message %#v to be a Welcome", msg)
+	}
+
+	if welcome.Type != "Welcome" {
+		t.Error("Message did not have the correct type")
+	}
+
+	if len(welcome.Users) != len(roomManager.roomUsers) {
+		t.Errorf("Expected to get users %#v, but was %#v", roomManager.roomUsers, welcome.Users)
+	}
+}
+
+func Test_ChannellingAPI_OnIncoming_HelloMessageWithAnIid_RespondsWithAnErrorIfTheRoomCannotBeJoined(t *testing.T) {
+	iid := "foo"
+	api, client, session, roomManager := NewTestChannellingAPI()
+	roomManager.disallowJoin = true
+
+	api.OnIncoming(client, session, &DataIncoming{Type: "Hello", Iid: iid, Hello: &DataHello{}})
+
+	msg, ok := client.replies[iid]
+	if !ok {
+		t.Fatalf("No response received for Iid %v", iid)
+	}
+
+	err, ok := msg.(*DataError)
+	if !ok {
+		t.Fatalf("Expected response message %#v to be an Error", msg)
+	}
+
+	if err.Type != "Error" {
+		t.Error("Message did not have the correct type")
+	}
+}