Rewrite location headers and body resp

README.md

@@ -27,18 +27,22 @@ From [Wikipedia](https://wikipedia.org/wiki/Reverse_proxy):
 
 Upstream servers can be listed per-domain in the following forms:
 
-- List of remote nodes, e.g. `["host:4000", "host:4001"]`
+- List of remote nodes, e.g. `["http://host:4000", "http://host:4001"]`
 - A `{plug, options}` tuple, useful for umbrella applications
 
 > Note: This structure may change in the future as the project progresses.
 
 ```elixir
 config :reverse_proxy,
   # ...
-  upstreams: %{ "api." => ["localhost:4000"],
-                "slogsdon.com" => ["localhost:4001"] }
+  upstreams: %{ "foobar.localhost" => ["http://www.example.com"],
+                "api." => ["http://localhost:4000"],
+                "slogsdon.com" => ["http://localhost:4001"] }
 ```
 
+You might need to create `foobar.localhost in `/etc/hosts` and replace
+example.com with an actual site.
+
 ### `:cache`
 
 Enables the caching of the responses from the upstream server.

config/config.exs

@@ -1,6 +1,9 @@
 use Mix.Config
 
-config :reverse_proxy,
-  upstreams: %{ "api." => {ReverseProxyTest.SuccessPlug, []},
-                "example.com" => {ReverseProxyTest.SuccessPlug, []},
-                "badgateway.com" => ["localhost:1"] }
+config(:reverse_proxy,
+       upstreams: %{
+         # You could add foobar.localhost to /etc/hosts to test this
+         "foobar.localhost" => ["http://www.example.com"],
+         "api." => {ReverseProxyTest.SuccessPlug, []},
+         "example.com" => {ReverseProxyTest.SuccessPlug, []},
+         "badgateway.com" => ["http://localhost:1"] })

lib/reverse_proxy/runner.ex

@@ -22,7 +22,7 @@ defmodule ReverseProxy.Runner do
 
     method
       |> client.request(url, body, headers, timeout: 5_000)
-      |> process_response(conn)
+      |> process_response(conn, server)
   end
 
   @spec prepare_request(String.t, Conn.t) :: {Atom.t,
@@ -40,7 +40,7 @@ defmodule ReverseProxy.Runner do
               "transfer-encoding"
             )
     method = conn.method |> String.downcase |> String.to_atom
-    url = "#{conn.scheme}://#{server}#{conn.request_path}?#{conn.query_string}"
+    url = "#{server}#{conn.request_path}?#{conn.query_string}"
     headers = conn.req_headers
     body = case Conn.read_body(conn) do
       {:ok, body, _conn} ->
@@ -70,20 +70,33 @@ defmodule ReverseProxy.Runner do
     {method, url, body, headers}
   end
 
-  @spec process_response({Atom.t, Map.t}, Conn.t) :: Conn.t
-  defp process_response({:error, _}, conn) do
-    conn |> Conn.send_resp(502, "Bad Gateway")
+  @spec process_response({Atom.t, Map.t}, Plug.Conn.t, String.t) :: Plug.Conn.t
+  defp process_response({:error, _}, conn, _server) do
+    conn |> Plug.Conn.send_resp(502, "Bad Gateway")
   end
-  defp process_response({:ok, response}, conn) do
+  defp process_response({:ok, response}, conn, server) do
+    conn = conn |> put_resp_headers(response.headers)
+
     conn
-      |> put_resp_headers(response.headers)
-      |> Conn.delete_resp_header("transfer-encoding")
-      |> Conn.send_resp(response.status_code, response.body)
+       |> put_resp_headers(response.headers)
+       |> Conn.delete_resp_header("transfer-encoding")
+       |> Conn.send_resp(response.status_code, response.body |> process_body(conn, server))
   end
 
   @spec put_resp_headers(Conn.t, [{String.t, String.t}]) :: Conn.t
   defp put_resp_headers(conn, []), do: conn
-  defp put_resp_headers(conn, [{header, value} | rest]) do
+  defp put_resp_headers(conn, [{header = "Location", value}|rest]) do
+    [host, port] = conn |> get_host() |> String.split(":")
+    value = URI.parse(value)
+          |> Map.put(:host, host)
+          |> Map.put(:port, port |> String.to_integer)
+          |> URI.to_string
+
+    conn
+      |> Plug.Conn.put_resp_header(header |> String.downcase, value)
+      |> put_resp_headers(rest)
+  end
+  defp put_resp_headers(conn, [{header, value}|rest]) do
     conn
       |> Conn.put_resp_header(header |> String.downcase, value)
       |> put_resp_headers(rest)
@@ -92,4 +105,15 @@ defmodule ReverseProxy.Runner do
   defp upstream_select(servers) do
     servers |> hd
   end
+
+  defp process_body(body, conn, server) do
+    body |> String.replace(server, conn |> get_host())
+  end
+
+  defp get_host(conn) do
+    case conn |> Plug.Conn.get_req_header("host") do
+      [head | _] -> head
+      _ -> ""
+    end
+  end
 end

test/reverse_proxy/runner_test.exs

@@ -95,6 +95,26 @@ defmodule ReverseProxy.RunnerTest do
     assert conn.resp_headers == headers
   end
 
+  test "retreive/3 - http - location header rewrite" do
+    conn = conn(:get, "/")
+     |> put_req_header("host", "localhost:4000")
+
+    conn = ReverseProxy.Runner.retreive(
+      conn,
+      ["localhost:5001"],
+      ReverseProxyTest.RedirectHTTP
+    )
+
+    assert conn.status == 301
+    assert conn.resp_body == """
+    <html><body>You are being <a href="http://localhost:4000/foo">redirected</a>.</body></html>
+    """
+    assert conn.resp_headers == [
+      {"cache-control", "max-age=0, private, must-revalidate"},
+      {"location", "http://localhost:4000/foo"},
+    ]
+  end
+
   test "retreive/3 - http - failure" do
     conn = conn(:get, "/")
 

test/support/redirect_http.ex

@@ -0,0 +1,17 @@
+defmodule ReverseProxyTest.RedirectHTTP do
+  def request(_method, _url, _body, _headers, _opts \\ []) do
+    {:ok, %{
+      headers: headers,
+      status_code: 301,
+      body: """
+      <html><body>You are being <a href="http://localhost:5001/foo">redirected</a>.</body></html>
+      """
+    }}
+  end
+  def headers do
+    [
+      {"cache-control", "max-age=0, private, must-revalidate"},
+      {"Location", "http://localhost:5001/foo"},
+    ]
+  end
+end