Requests hang forever when using integers as values in multipart

[helderbarboza]

Environment

uname -a output:

Linux hostname-pc 4.17.3-100.fc27.x86_64 #1 SMP Tue Jun 26 14:19:03 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux

elixir --version output:

Erlang/OTP 20 [erts-9.2] [source] [64-bit] [smp:4:4] [ds:4:4:10] [async-threads:10] [hipe] [kernel-poll:false]

Elixir 1.6.2 (compiled with OTP 19)

Current behavior

When passing a integer value as third argument to add_field/4, it never returns when executing the request:

alias Tesla.Multipart
chat_id_int = -1_001_143_002_998
token = Application.get_env(:tg, :token)

mp =
  Multipart.new()
  |> Multipart.add_field("chat_id", chat_id_int)
  |> Multipart.add_file("test.txt", name: "document")

Tesla.post("https://api.telegram.org/bot#{token}/sendDocument", mp) # Hangs forever

This works fine:

alias Tesla.Multipart
chat_id_str = "-1001143002998"
token = Application.get_env(:tg, :token)

mp =
  Multipart.new()
  |> Multipart.add_field("chat_id", chat_id_str)
  |> Multipart.add_file("test.txt", name: "document")

Tesla.post("https://api.telegram.org/bot#{token}/sendDocument", mp)

Expected behavior

I would expect it to either work fine with integers or to throw an error when I try to pass something that is not a string, whichever makes more sense.

[teamon]

I can't test this right now, please try to produce the failing minimal example against requestbin or similar service.

[helderbarboza]

Using string:

mp =
  Multipart.new()
  |> Multipart.add_field("foo", "123")

Tesla.post("http://requestbin.net/r/1mw0e3c1", mp)

Output:

{:ok,
 %Tesla.Env{
   __client__: %Tesla.Client{fun: nil, post: [], pre: []},
   __module__: Tesla,
   body: "ip:177.124.185.70\n",
   headers: [
     {"connection", "keep-alive"},
     {"date", "Wed, 18 Jul 2018 20:22:07 GMT"},
     {"via", "1.1 vegur"},
     {"server", "cloudflare"},
     {"content-length", "18"},
     {"content-type", "text/html; charset=utf-8"},
     {"set-cookie",
      "__cfduid=d0511378e77d3b91c1043de753a3482371531945327; expires=Thu, 18-Jul-19 20:22:07 GMT; path=/; domain=.requestbin.net; HttpOnly"},
     {"sponsored-by", "http://requestbin.net"},
     {"cf-ray", "43c7a897729ab8b9-MIA"}
   ],
   method: :post,
   opts: [],
   query: [],
   status: 200,
   url: "http://requestbin.net/r/1mw0e3c1"
 }}

Using integer:

mp =
  Multipart.new()
  |> Multipart.add_field("foo", 123)

Tesla.post("http://requestbin.net/r/1mw0e3c1", mp)

Never outputs.

[teamon]

The hanging part is because of httpc (the default adapter). However, the body should be an Enumerable. When it's binary it's converted to [body] by tesla.

The error is much more clear when used with hackney adapter:

** (Protocol.UndefinedError) protocol Enumerable not implemented for 123. This protocol is implemented for: Date.Range, File.Stream, Function, GenEvent.Stream, HashDict, HashSet, IO.Stream, List, Map, MapSet, Range, Stream
    (elixir) /home/ubuntu/bob/tmp/e00399d85b8d200de0c17f19231c78a9/elixir/lib/elixir/lib/enum.ex:1: Enumerable.impl_for!/1
    (elixir) /home/ubuntu/bob/tmp/e00399d85b8d200de0c17f19231c78a9/elixir/lib/elixir/lib/enum.ex:141: Enumerable.reduce/3
    (elixir) lib/stream.ex:923: Stream.do_enum_transform/7
    (elixir) lib/enum.ex:1919: Enum.reduce/3
    (tesla) lib/tesla/adapter/hackney.ex:74: Tesla.Adapter.Hackney.request_stream/5
    (tesla) lib/tesla/adapter/hackney.ex:31: Tesla.Adapter.Hackney.call/2

I think we need to add a guard to Multipart.add_field/3 to prevent passing unsupported data.