Add separate Protocol for INIT_JS5REMOTE_CONNECTION responses

This allows us to deal with a single corner case of the same opcode
being used for two slightly different login response packets, depending
on the request.

archive/src/main/kotlin/org/openrs2/archive/cache/OsrsJs5ChannelInitializer.kt

@@ -12,7 +12,7 @@ public class OsrsJs5ChannelInitializer(private val handler: OsrsJs5ChannelHandle
         ch.pipeline().addLast(
             ReadTimeoutHandler(30),
             Rs2Encoder(Protocol.LOGIN_UPSTREAM),
-            Rs2Decoder(Protocol.LOGIN_DOWNSTREAM)
+            Rs2Decoder(Protocol.LOGIN_DOWNSTREAM_JS5REMOTE)
         )
         ch.pipeline().addLast("handler", handler)
     }

game/src/main/kotlin/org/openrs2/game/net/login/LoginChannelHandler.kt

@@ -49,6 +49,9 @@ public class LoginChannelHandler @Inject constructor(
     }
 
     private fun handleInitJs5RemoteConnection(ctx: ChannelHandlerContext, msg: LoginRequest.InitJs5RemoteConnection) {
+        val encoder = ctx.pipeline().get(Rs2Encoder::class.java)
+        encoder.protocol = Protocol.LOGIN_DOWNSTREAM_JS5REMOTE
+
         if (msg.build != BUILD) {
             ctx.write(LoginResponse.ClientOutOfDate).addListener(ChannelFutureListener.CLOSE)
             return
@@ -64,7 +67,7 @@ public class LoginChannelHandler @Inject constructor(
 
         ctx.write(LoginResponse.Js5Ok).addListener { future ->
             if (future.isSuccess) {
-                ctx.pipeline().remove(Rs2Encoder::class.java)
+                ctx.pipeline().remove(encoder)
                 ctx.pipeline().remove(this)
             }
         }

protocol/src/main/kotlin/org/openrs2/protocol/Protocol.kt

@@ -39,12 +39,27 @@ public class Protocol(vararg codecs: PacketCodec<*>) {
             RequestWorldListCodec,
             InitCrossDomainConnectionCodec
         )
+
         public val LOGIN_DOWNSTREAM: Protocol = Protocol(
+            ClientOutOfDateCodec,
+            ServerFullCodec,
+            IpLimitCodec
+        )
+
+        /**
+         * Unfortunately the Js5Ok packet's opcode overlaps with the exchange
+         * session keys opcode - the only case where this happens. We therefore
+         * have two LOGIN_DOWNSTREAM protocols to avoid ambiguity: one for
+         * responses to the InitJs5RemoteConnection packet, and one for
+         * responses to all other login packets.
+         */
+        public val LOGIN_DOWNSTREAM_JS5REMOTE: Protocol = Protocol(
             Js5OkCodec,
             ClientOutOfDateCodec,
             ServerFullCodec,
             IpLimitCodec
         )
+
         public val WORLD_LIST_DOWNSTREAM: Protocol = Protocol(
             WorldListResponseCodec
         )