1%% This Source Code Form is subject to the terms of the Mozilla Public
2%% License, v. 2.0. If a copy of the MPL was not distributed with this
3%% file, You can obtain one at https://mozilla.org/MPL/2.0/.
4%%
5%% Copyright (c) 2007-2021 VMware, Inc. or its affiliates.  All rights reserved.
6%%
7
8-module(rabbit_auth_mechanism_plain).
9-include_lib("rabbit_common/include/rabbit.hrl").
10
11-behaviour(rabbit_auth_mechanism).
12
13-export([description/0, should_offer/1, init/1, handle_response/2]).
14
15-rabbit_boot_step({?MODULE,
16                   [{description, "auth mechanism plain"},
17                    {mfa,         {rabbit_registry, register,
18                                   [auth_mechanism, <<"PLAIN">>, ?MODULE]}},
19                    {requires,    rabbit_registry},
20                    {enables,     kernel_ready}]}).
21
22%% SASL PLAIN, as used by the Qpid Java client and our clients. Also,
23%% apparently, by OpenAMQ.
24
25description() ->
26    [{description, <<"SASL PLAIN authentication mechanism">>}].
27
28should_offer(_Sock) ->
29    true.
30
31init(_Sock) ->
32    [].
33
34handle_response(Response, _State) ->
35    case extract_user_pass(Response) of
36        {ok, User, Pass} ->
37            rabbit_access_control:check_user_pass_login(User, Pass);
38        error ->
39            {protocol_error, "response ~p invalid", [Response]}
40    end.
41
42extract_user_pass(Response) ->
43    case extract_elem(Response) of
44        {ok, User, Response1} -> case extract_elem(Response1) of
45                                     {ok, Pass, <<>>} -> {ok, User, Pass};
46                                     _                -> error
47                                 end;
48        error                 -> error
49    end.
50
51extract_elem(<<0:8, Rest/binary>>) ->
52    Count = next_null_pos(Rest, 0),
53    <<Elem:Count/binary, Rest1/binary>> = Rest,
54    {ok, Elem, Rest1};
55extract_elem(_) ->
56    error.
57
58next_null_pos(<<>>, Count)                  -> Count;
59next_null_pos(<<0:8, _Rest/binary>>, Count) -> Count;
60next_null_pos(<<_:8, Rest/binary>>,  Count) -> next_null_pos(Rest, Count + 1).
61