Remove code dup

Reuse class methods from `Rack::Proxy` courtesy of the `rack-proxy` gem

Author: janraasch

lib/rack/reverse_proxy.rb

@@ -18,7 +18,7 @@ def initialize(app = nil, &b)
 
     def call(env)
       rackreq = Rack::Request.new(env)
-      matcher = get_matcher(rackreq.fullpath, extract_http_request_headers(rackreq.env), rackreq)
+      matcher = get_matcher(rackreq.fullpath, Proxy.extract_http_request_headers(rackreq.env), rackreq)
       return @app.call(env) if matcher.nil?
 
       if @global_options[:newrelic_instrumentation]
@@ -44,7 +44,7 @@ def proxy(env, source_request, matcher)
       target_request = Net::HTTP.const_get(source_request.request_method.capitalize).new(uri.request_uri)
 
       # Setup headers
-      target_request_headers = extract_http_request_headers(source_request.env)
+      target_request_headers = Proxy.extract_http_request_headers(source_request.env)
 
       if options[:preserve_host]
         if uri.port == uri.default_port
@@ -96,26 +96,6 @@ def proxy(env, source_request, matcher)
       [target_response.status, response_headers, target_response.body]
     end
 
-    def extract_http_request_headers(env)
-      headers = env.reject do |k, v|
-        !(/^HTTP_[A-Z_]+$/ === k) || v.nil?
-      end.map do |k, v|
-        [reconstruct_header_name(k), v]
-      end.inject(Utils::HeaderHash.new) do |hash, k_v|
-        k, v = k_v
-        hash[k] = v
-        hash
-      end
-
-      x_forwarded_for = (headers["X-Forwarded-For"].to_s.split(/, +/) << env["REMOTE_ADDR"]).join(", ")
-
-      headers.merge!("X-Forwarded-For" =>  x_forwarded_for)
-    end
-
-    def reconstruct_header_name(name)
-      name.sub(/^HTTP_/, "").gsub("_", "-")
-    end
-
     def get_matcher(path, headers, rackreq)
       matches = @matchers.select do |matcher|
         matcher.match?(path, headers, rackreq)