proxy_pass: send 1.0 requests to upstreams for 1.0 clients

We cannot pass trailers from upstreams to HTTP/1.0 clients without
fully-buffering the response body AND trailers before forwarding the
response header.

Of course, one of the reasons yahns exists is to support lazy
buffering, so fully-buffering up front is wasteful and hurts
latency.  So instead, degrade to 1.0 requests to upstreams for
HTTP/1.0 clients, this should prevent upstreams from sending
trailers in the first place.

HTTP/1.0 clients on Rails apps may suffer, but there probably
are not too many HTTP/1.0 clients out there.

1 files changed, 7 insertions, 1 deletions

diff --git a/lib/yahns/proxy_pass.rb b/lib/yahns/proxy_pass.rb
index 3812dbf..e3ba7f0 100644
--- a/lib/yahns/proxy_pass.rb
+++ b/lib/yahns/proxy_pass.rb
@@ -205,7 +205,13 @@ class Yahns::ProxyPass # :nodoc:
     req = @path.gsub(/\$(\w+)/) { req.__send__($1) }
 
     # start the connection asynchronously and early so TCP can do a
-    req = "#{env['REQUEST_METHOD']} #{req} HTTP/1.1\r\n" \
+    case ver = env['HTTP_VERSION']
+    when 'HTTP/1.1' # leave alone, response may be chunked
+    else # no chunking for HTTP/1.0 and HTTP/0.9
+      ver = 'HTTP/1.0'.freeze
+    end
+
+    req = "#{env['REQUEST_METHOD']} #{req} #{ver}\r\n" \
           "X-Forwarded-For: #{env["REMOTE_ADDR"]}\r\n"
 
     # pass most HTTP_* headers through as-is