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%% This Source Code Form is subject to the terms of the Mozilla Public
%% License, v. 2.0. If a copy of the MPL was not distributed with this
%% file, You can obtain one at https://mozilla.org/MPL/2.0/.
%%
%% Copyright (c) 2007-2021 VMware, Inc. or its affiliates. All rights reserved.
%%
-module(rabbit_web_dispatch_registry).
-behaviour(gen_server).
-export([start_link/0]).
-export([add/5, remove/1, set_fallback/2, lookup/2, list_all/0]).
-export([init/1, handle_call/3, handle_cast/2, handle_info/2, terminate/2,
code_change/3]).
-export([list/1]).
-import(rabbit_misc, [pget/2]).
-define(ETS, rabbitmq_web_dispatch).
%% This gen_server is merely to serialise modifications to the dispatch
%% table for listeners.
start_link() ->
gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).
add(Name, Listener, Selector, Handler, Link) ->
gen_server:call(?MODULE, {add, Name, Listener, Selector, Handler, Link},
infinity).
remove(Name) ->
gen_server:call(?MODULE, {remove, Name}, infinity).
%% @todo This needs to be dispatch instead of a fun too.
%% But I'm not sure what code is using this.
set_fallback(Listener, FallbackHandler) ->
gen_server:call(?MODULE, {set_fallback, Listener, FallbackHandler},
infinity).
lookup(Listener, Req) ->
case lookup_dispatch(Listener) of
{ok, {Selectors, Fallback}} ->
case catch match_request(Selectors, Req) of
{'EXIT', Reason} -> {error, {lookup_failure, Reason}};
not_found -> {ok, Fallback};
Dispatch -> {ok, Dispatch}
end;
Err ->
Err
end.
%% This is called in a somewhat obfuscated manner in
%% rabbit_mgmt_external_stats:rabbit_web_dispatch_registry_list_all()
list_all() ->
gen_server:call(?MODULE, list_all, infinity).
%% Callback Methods
init([]) ->
?ETS = ets:new(?ETS, [named_table, public]),
{ok, undefined}.
handle_call({add, Name, Listener, Selector, Handler, Link = {_, Desc}}, _From,
undefined) ->
Continue = case rabbit_web_dispatch_sup:ensure_listener(Listener) of
new -> set_dispatch(
Listener, [],
listing_fallback_handler(Listener)),
listener_started(Listener),
true;
existing -> true;
ignore -> false
end,
case Continue of
true -> case lookup_dispatch(Listener) of
{ok, {Selectors, Fallback}} ->
Selector2 = lists:keystore(
Name, 1, Selectors,
{Name, Selector, Handler, Link}),
set_dispatch(Listener, Selector2, Fallback);
{error, {different, Desc2, Listener2}} ->
exit({incompatible_listeners,
{Desc, Listener}, {Desc2, Listener2}})
end;
false -> ok
end,
{reply, ok, undefined};
handle_call({remove, Name}, _From,
undefined) ->
case listener_by_name(Name) of
{error, not_found} ->
rabbit_log:warning("HTTP listener registry could not find context ~p",
[Name]),
{reply, ok, undefined};
{ok, Listener} ->
{ok, {Selectors, Fallback}} = lookup_dispatch(Listener),
Selectors1 = lists:keydelete(Name, 1, Selectors),
set_dispatch(Listener, Selectors1, Fallback),
case Selectors1 of
[] -> rabbit_web_dispatch_sup:stop_listener(Listener),
listener_stopped(Listener);
_ -> ok
end,
{reply, ok, undefined}
end;
handle_call({set_fallback, Listener, FallbackHandler}, _From,
undefined) ->
{ok, {Selectors, _OldFallback}} = lookup_dispatch(Listener),
set_dispatch(Listener, Selectors, FallbackHandler),
{reply, ok, undefined};
handle_call(list_all, _From, undefined) ->
{reply, list(), undefined};
handle_call(Req, _From, State) ->
rabbit_log:error("Unexpected call to ~p: ~p~n", [?MODULE, Req]),
{stop, unknown_request, State}.
handle_cast(_, State) ->
{noreply, State}.
handle_info(_, State) ->
{noreply, State}.
terminate(_, _) ->
true = ets:delete(?ETS),
ok.
code_change(_, State, _) ->
{ok, State}.
%%---------------------------------------------------------------------------
%% Internal Methods
listener_started(Listener) ->
[rabbit_networking:tcp_listener_started(Protocol, Listener, IPAddress, Port)
|| {Protocol, IPAddress, Port} <- listener_info(Listener)],
ok.
listener_stopped(Listener) ->
[rabbit_networking:tcp_listener_stopped(Protocol, Listener, IPAddress, Port)
|| {Protocol, IPAddress, Port} <- listener_info(Listener)],
ok.
listener_info(Listener) ->
Protocol = case pget(protocol, Listener) of
undefined ->
case pget(ssl, Listener) of
true -> https;
_ -> http
end;
P ->
P
end,
Port = pget(port, Listener),
[{Protocol, IPAddress, Port}
|| {IPAddress, _Port, _Family}
<- rabbit_networking:tcp_listener_addresses(Port)].
lookup_dispatch(Lsnr) ->
case ets:lookup(?ETS, pget(port, Lsnr)) of
[{_, Lsnr, S, F}] -> {ok, {S, F}};
[{_, Lsnr2, S, _F}] -> {error, {different, first_desc(S), Lsnr2}};
[] -> {error, {no_record_for_listener, Lsnr}}
end.
first_desc([{_N, _S, _H, {_, Desc}} | _]) -> Desc.
set_dispatch(Listener, Selectors, Fallback) ->
ets:insert(?ETS, {pget(port, Listener), Listener, Selectors, Fallback}).
match_request([], _) ->
not_found;
match_request([{_Name, Selector, Dispatch, _Link}|Rest], Req) ->
case Selector(Req) of
true -> Dispatch;
false -> match_request(Rest, Req)
end.
list() ->
[{Path, Desc, Listener} ||
{_P, Listener, Selectors, _F} <- ets:tab2list(?ETS),
{_N, _S, _H, {Path, Desc}} <- Selectors].
-spec listener_by_name(atom()) -> {ok, term()} | {error, not_found}.
listener_by_name(Name) ->
case [L || {_P, L, S, _F} <- ets:tab2list(?ETS), contains_name(Name, S)] of
[Listener] -> {ok, Listener};
[] -> {error, not_found}
end.
contains_name(Name, Selectors) ->
lists:member(Name, [N || {N, _S, _H, _L} <- Selectors]).
list(Listener) ->
{ok, {Selectors, _Fallback}} = lookup_dispatch(Listener),
[{Path, Desc} || {_N, _S, _H, {Path, Desc}} <- Selectors].
%%---------------------------------------------------------------------------
listing_fallback_handler(Listener) ->
cowboy_router:compile([{'_', [
{"/", rabbit_web_dispatch_listing_handler, Listener}
]}]).
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