[[RFC]] http_client: hijack after 100-continue disables HTTP response

[Eric Wong <e@80x24.org>]

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.
---
 lib/yahns/http_client.rb | 7 +++++--
 1 file 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
 
-- 
EW