http proxy example, from: https://gist.github.com/794464

examples/http_proxy.rb

@@ -0,0 +1,47 @@
+require 'em-proxy'
+require 'http/parser' # gem install http_parser.rb
+require 'uuid'        # gem install uuid
+
+# > ruby em-proxy-http.rb
+# > curl --proxy localhost:9889 www.google.com
+
+host = "0.0.0.0"
+port = 9889
+puts "listening on #{host}:#{port}..."
+
+Proxy.start(:host => host, :port => port) do |conn|
+
+  @p = Http::Parser.new
+  @p.on_headers_complete = proc do |h|
+    session = UUID.generate
+    puts "New session: #{session} (#{h.inspect})"
+
+    host, port = h['Host'].split(':')
+    conn.server session, :host => host, :port => (port || 80)
+    conn.relay_to_servers @buffer
+
+    @buffer.clear
+  end
+
+  @buffer = ''
+
+  conn.on_connect do |data,b|
+    puts [:on_connect, data, b].inspect
+  end
+
+  conn.on_data do |data|
+    @buffer << data
+    @p << data
+
+    data
+  end
+
+  conn.on_response do |backend, resp|
+    puts [:on_response, backend, resp].inspect
+    resp
+  end
+
+  conn.on_finish do |backend, name|
+    puts [:on_finish, name].inspect
+  end
+end