Proxied requests confuse the URI parser

[SGrondin]

When I set the system-wide HTTP proxy on Debian to forward all traffic to a Cohttp application, the calls come in as GET //simongrondin.name/files/fifty.txt instead of GET http://simongrondin.name/files/fifty.txt.

The URI parser gets confused and interprets them like this:

Uri.to_string (Request.uri req)
> http://simongrondin.namehttp//simongrondin.name/files/fifty.txt

[rgrinberg]

Are there any headers that come with this GET //simongrondin.name/files/fifty.txt request? I'm looking at a host header specifically.

[SGrondin]

Host is, as expected, Host: simongrondin.name

[rgrinberg]

OK, so this is the culprit: https://github.com/mirage/ocaml-cohttp/blob/master/lib/request.ml#L97

[SGrondin]

By the way it's easier to reproduce by setting the Firefox HTTP proxy setting to a local cohttp server.

[dsheets]

@rgrinberg are you on this? It looks like d04701f#diff-daa4e580cf195143c70372b6183a5a40R140 should really be using proper Uri functional updates rather than string concatenation (will handle relative paths correctly). Also, I'd recommend switching to a scheme-relative identifiers.

[rgrinberg]

@dsheets I'd like to fix this by next week. A fix from you would be much appreciated since I'm not sure of proper Uri usage.

[SGrondin]

This is the absolutely horrible hack I'm using for now, but it works until a fix is (hopefully) released in 0.16. I put it here in case anyone googled and found this issue.

I would like to apologize to the gods of ocaml for this horror.

let fix_uri uri =
    let ungarble uri host protocol_len =
        uri
        |> fun uri -> ((Uri.with_host uri (Some (String.slice host 0 (-protocol_len)))), (String.length host - protocol_len))
        |> fun (uri, len) -> Uri.with_path uri (String.slice (Uri.path uri) (len + 2) 0)
    in
    match (uri |> Uri.host |> Option.value ~default:"") with
    | host when String.is_suffix ~suffix:"http" host -> ungarble uri host 4
    | host when String.is_suffix ~suffix:"https" host -> ungarble uri host 5
    | host when (((String.length host) / 2) mod 2 = 0) && ((String.slice host (String.length host / 2) 0) = (String.slice host 0 (String.length host / 2))) ->
            Uri.with_host uri (Some (String.slice host 0 (String.length host / 2)))
    | _ -> uri

[avsm]

I stuck a functional update fix into avsm/ocaml-cohttp@0260455, but uri is doing some odd things:

#require "uri.top"
Uri.with_port (Uri.of_string "/") None ;;
- : Uri.t = ///
Uri.of_string "/" ;;
- : Uri.t = /

Those should really be equivalent.

[avsm]

See mirage/ocaml-uri#63

[SGrondin]

This is still happening even with Uri 1.8.0.

http://en.wikipedia.orghttp//en.wikipedia.org/wiki/GNU_C_Library

[rgrinberg]

@SGrondin I assume using cohttp master as well?

[SGrondin]

0.15.2

Oh, I didn't see it was closed in 37bcbd8. For some reason I thought it was in Uri 1.8.0.