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Implement WebSocket support based on Plug.Conn.Adapter.upgrade/3 (#88)
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@@ -16,7 +16,7 @@ jobs: | |
matrix: | ||
include: | ||
- pair: | ||
elixir: 1.7.4 | ||
elixir: 1.10.4 | ||
otp: 22.3.4 | ||
- pair: | ||
elixir: 1.11.4 | ||
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defmodule WebSocketHandlerTest do | ||
use ExUnit.Case, async: true | ||
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defmodule WebSocketHandler do | ||
@behaviour :cowboy_websocket | ||
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# We never actually call this; it's just here to quell compiler warnings | ||
@impl true | ||
def init(req, state), do: {:cowboy_websocket, req, state} | ||
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@impl true | ||
def websocket_init(_opts), do: {:ok, :init} | ||
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@impl true | ||
def websocket_handle({:text, "state"}, state), do: {[{:text, inspect(state)}], state} | ||
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def websocket_handle({:text, "whoami"}, state), | ||
do: {[{:text, :erlang.pid_to_list(self())}], state} | ||
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@impl true | ||
def websocket_info(msg, state), do: {[{:text, inspect(msg)}], state} | ||
end | ||
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@protocol_options [ | ||
idle_timeout: 1000, | ||
request_timeout: 1000 | ||
] | ||
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setup_all do | ||
{:ok, _} = Plug.Cowboy.http(__MODULE__, [], port: 8083, protocol_options: @protocol_options) | ||
on_exit(fn -> :ok = Plug.Cowboy.shutdown(__MODULE__.HTTP) end) | ||
{:ok, port: 8083} | ||
end | ||
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@behaviour Plug | ||
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@impl Plug | ||
def init(arg), do: arg | ||
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@impl Plug | ||
def call(conn, _opts) do | ||
conn = Plug.Conn.fetch_query_params(conn) | ||
handler = conn.query_params["handler"] |> String.to_atom() | ||
Plug.Conn.upgrade_adapter(conn, :websocket, {handler, [], %{idle_timeout: 1000}}) | ||
end | ||
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test "websocket_init and websocket_handle are called", context do | ||
client = tcp_client(context) | ||
http1_handshake(client, WebSocketHandler) | ||
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send_text_frame(client, "state") | ||
{:ok, result} = recv_text_frame(client) | ||
assert result == inspect(:init) | ||
end | ||
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test "websocket_info is called", context do | ||
client = tcp_client(context) | ||
http1_handshake(client, WebSocketHandler) | ||
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send_text_frame(client, "whoami") | ||
{:ok, pid} = recv_text_frame(client) | ||
pid = pid |> String.to_charlist() |> :erlang.list_to_pid() | ||
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Process.send(pid, "hello info", []) | ||
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{:ok, response} = recv_text_frame(client) | ||
assert response == inspect("hello info") | ||
end | ||
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# Simple WebSocket client | ||
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def tcp_client(context) do | ||
{:ok, socket} = :gen_tcp.connect('localhost', context[:port], active: false, mode: :binary) | ||
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socket | ||
end | ||
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def http1_handshake(client, module, params \\ []) do | ||
params = params |> Keyword.put(:handler, module) | ||
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:gen_tcp.send(client, """ | ||
GET /?#{URI.encode_query(params)} HTTP/1.1\r | ||
Host: server.example.com\r | ||
Upgrade: websocket\r | ||
Connection: Upgrade\r | ||
Sec-WebSocket-Key: dGhlIHNhbXBsZSBub25jZQ==\r | ||
Sec-WebSocket-Version: 13\r | ||
\r | ||
""") | ||
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{:ok, response} = :gen_tcp.recv(client, 234) | ||
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[ | ||
"HTTP/1.1 101 Switching Protocols", | ||
"cache-control: max-age=0, private, must-revalidate", | ||
"connection: Upgrade", | ||
"date: " <> _date, | ||
"sec-websocket-accept: s3pPLMBiTxaQ9kYGzzhZRbK+xOo=", | ||
"server: Cowboy", | ||
"upgrade: websocket", | ||
"", | ||
"" | ||
] = String.split(response, "\r\n") | ||
end | ||
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defp recv_text_frame(client) do | ||
{:ok, 0x8, 0x1, body} = recv_frame(client) | ||
{:ok, body} | ||
end | ||
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defp recv_frame(client) do | ||
{:ok, header} = :gen_tcp.recv(client, 2) | ||
<<flags::4, opcode::4, 0::1, length::7>> = header | ||
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{:ok, data} = | ||
case length do | ||
0 -> | ||
{:ok, <<>>} | ||
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126 -> | ||
{:ok, <<length::16>>} = :gen_tcp.recv(client, 2) | ||
:gen_tcp.recv(client, length) | ||
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127 -> | ||
{:ok, <<length::64>>} = :gen_tcp.recv(client, 8) | ||
:gen_tcp.recv(client, length) | ||
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length -> | ||
:gen_tcp.recv(client, length) | ||
end | ||
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{:ok, flags, opcode, data} | ||
end | ||
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defp send_text_frame(client, data, flags \\ 0x8) do | ||
send_frame(client, flags, 0x1, data) | ||
end | ||
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defp send_frame(client, flags, opcode, data) do | ||
mask = :rand.uniform(1_000_000) | ||
masked_data = mask(data, mask) | ||
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mask_flag_and_size = | ||
case byte_size(masked_data) do | ||
size when size <= 125 -> <<1::1, size::7>> | ||
size when size <= 65_535 -> <<1::1, 126::7, size::16>> | ||
size -> <<1::1, 127::7, size::64>> | ||
end | ||
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:gen_tcp.send(client, [<<flags::4, opcode::4>>, mask_flag_and_size, <<mask::32>>, masked_data]) | ||
end | ||
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# Note that masking is an involution, so we don't need a separate unmask function | ||
defp mask(payload, mask, acc \\ <<>>) | ||
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defp mask(payload, mask, acc) when is_integer(mask), do: mask(payload, <<mask::32>>, acc) | ||
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defp mask(<<h::32, rest::binary>>, <<mask::32>>, acc) do | ||
mask(rest, mask, acc <> <<Bitwise.bxor(h, mask)::32>>) | ||
end | ||
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defp mask(<<h::8, rest::binary>>, <<current::8, mask::24>>, acc) do | ||
mask(rest, <<mask::24, current::8>>, acc <> <<Bitwise.bxor(h, current)::8>>) | ||
end | ||
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defp mask(<<>>, _mask, acc), do: acc | ||
end |