http_client: hijack after 100-continue disables HTTP response

While rack.hijack usage during application dispatch normally
prevents yahns from writing an HTTP response out of the Rack
response array, this was not correctly prevented when the
application emitted a 100-continue response when the client
was was too slow to read the 100-continue response without
triggering response buffering the server.

This bug only affects exceeding rare apps which rely on both
rack.hijack use during app dispatch _and_ emits 100-continue
responses, and even then it only affects slow clients which
refuse to read the 100-continue response sent by yahns without
blocking.

1 files changed, 5 insertions, 2 deletions

diff --git a/lib/yahns/http_client.rb b/lib/yahns/http_client.rb
index 1c3c8dd..235decd 100644
--- a/lib/yahns/http_client.rb
+++ b/lib/yahns/http_client.rb
@@ -179,8 +179,9 @@ class Yahns::HttpClient < Kgio::Socket # :nodoc:
     handle_error(e)
   end
 
+  # only called when buffering slow clients
   # returns :wait_readable, :wait_writable, :ignore, or nil for epoll
-  # returns false to keep looping inside yahns_step
+  # returns true to keep looping inside yahns_step
   def r100_done
     k = self.class
     case k.input_buffering
@@ -193,7 +194,9 @@ class Yahns::HttpClient < Kgio::Socket # :nodoc:
       mkinput_preread # keep looping (@state == :body)
       true
     else # :lazy, false
-      http_response_write(*k.app.call(@hs.env))
+      r = k.app.call(env = @hs.env)
+      return :ignore if env.include?(RACK_HIJACK_IO)
+      http_response_write(*r)
     end
   end