From 4d8c1f72a6d24d02ce78d2940bcec74648a43d1e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Carl=20H=C3=B6rberg?= <carl@84codes.com>
Date: Sun, 12 May 2024 14:30:26 +0200
Subject: [PATCH] Negotiate frame_max with Upstream

---
 src/amqproxy/upstream.cr | 26 +++++++++++++-------------
 1 file changed, 13 insertions(+), 13 deletions(-)

diff --git a/src/amqproxy/upstream.cr b/src/amqproxy/upstream.cr
index 03e7369..d767187 100644
--- a/src/amqproxy/upstream.cr
+++ b/src/amqproxy/upstream.cr
@@ -6,14 +6,15 @@ require "./channel_pool"
 
 module AMQProxy
   class Upstream
-    Log      = ::Log.for(self)
-    FrameMax = 4096_u32
+    Log = ::Log.for(self)
     @socket : IO
     @channels = Hash(UInt16, DownstreamChannel).new
     @channels_lock = Mutex.new
     @channel_max : UInt16
     @lock = Mutex.new
     @remote_address : String
+    @channel_max : UInt16
+    @frame_max : UInt32
 
     def initialize(@host : String, @port : Int32, @tls_ctx : OpenSSL::SSL::Context::Client?, credentials)
       tcp_socket = TCPSocket.new(@host, @port)
@@ -32,7 +33,9 @@ module AMQProxy
         else
           tcp_socket
         end
-      @channel_max = start(credentials)
+      tune_ok = start(credentials)
+      @channel_max = tune_ok.channel_max
+      @frame_max = tune_ok.frame_max
     end
 
     def open_channel_for(downstream_channel : DownstreamChannel) : UpstreamChannel
@@ -155,14 +158,10 @@ module AMQProxy
 
     private def expect_more_publish_frames?(frame) : Bool
       case frame
-      when AMQ::Protocol::Frame::Basic::Publish
-        return true
-      when AMQ::Protocol::Frame::Header
-        return true unless frame.body_size.zero?
-      when AMQ::Protocol::Frame::BytesBody
-        return true if frame.bytesize == FrameMax
+      when AMQ::Protocol::Frame::Basic::Publish then true
+      when AMQ::Protocol::Frame::Header         then frame.body_size != 0
+      else                                           false
       end
-      false
     end
 
     def close(reason = "")
@@ -180,7 +179,7 @@ module AMQProxy
       @socket.closed?
     end
 
-    private def start(credentials) : UInt16
+    private def start(credentials) : AMQ::Protocol::Frame::Connection::TuneOk
       @socket.write AMQ::Protocol::PROTOCOL_START_0_9_1.to_slice
       @socket.flush
 
@@ -195,7 +194,8 @@ module AMQProxy
       case tune = AMQ::Protocol::Frame.from_io(@socket)
       when AMQ::Protocol::Frame::Connection::Tune
         channel_max = tune.channel_max.zero? ? UInt16::MAX : tune.channel_max
-        tune_ok = AMQ::Protocol::Frame::Connection::TuneOk.new(channel_max, FrameMax, tune.heartbeat)
+        frame_max = tune.frame_max.zero? ? 131072_u32 : Math.min(131072_u32, tune.frame_max)
+        tune_ok = AMQ::Protocol::Frame::Connection::TuneOk.new(channel_max, frame_max, tune.heartbeat)
         @socket.write_bytes tune_ok, IO::ByteFormat::NetworkEndian
         @socket.flush
       when AMQ::Protocol::Frame::Connection::Close
@@ -217,7 +217,7 @@ module AMQProxy
       else
         raise "Unexpected frame on connection to upstream: #{f}"
       end
-      channel_max
+      tune_ok
     rescue ex : AccessError
       raise ex
     rescue ex