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Diffstat (limited to 'lib/diameter/src/base/diameter_dist.erl')
| -rw-r--r-- | lib/diameter/src/base/diameter_dist.erl | 535 |
1 files changed, 535 insertions, 0 deletions
diff --git a/lib/diameter/src/base/diameter_dist.erl b/lib/diameter/src/base/diameter_dist.erl new file mode 100644 index 0000000000..ed23152b8b --- /dev/null +++ b/lib/diameter/src/base/diameter_dist.erl @@ -0,0 +1,535 @@ +%% +%% %CopyrightBegin% +%% +%% Copyright Ericsson AB 2019. All Rights Reserved. +%% +%% Licensed under the Apache License, Version 2.0 (the "License"); +%% you may not use this file except in compliance with the License. +%% You may obtain a copy of the License at +%% +%% http://www.apache.org/licenses/LICENSE-2.0 +%% +%% Unless required by applicable law or agreed to in writing, software +%% distributed under the License is distributed on an "AS IS" BASIS, +%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +%% See the License for the specific language governing permissions and +%% limitations under the License. +%% +%% %CopyrightEnd% +%% + +-module(diameter_dist). + +-behaviour(gen_server). + +%% +%% Implements callbacks that can be configured as a spawn_opt +%% transport configuration, to be able to distribute incoming Diameter +%% requests to handler processes (local or remote) in various ways. +%% + +%% spawn_opt callbacks +-export([spawn_local/2, + spawn_local/1, + route_session/2, + route_session/1]). + +%% signal availability for handling incoming requests to route_sesssion/2 +-export([attach/1, + detach/1]). + +%% consistent hashing +-export([hash/3, %% for use as default MFA in route_session/2 options map + hash/2]). %% arbitrary key/values + +-include_lib("diameter/include/diameter.hrl"). + +%% server start +-export([start_link/0]). + +%% gen_server callbacks +-export([init/1, + handle_info/2, + handle_cast/2, + handle_call/3, + code_change/3, + terminate/2]). + +-type request() :: tuple(). %% callback argument from diameter_traffic + +-define(SERVER, ?MODULE). %% server monitoring node connections + +%% Maps a node name binary to the corresponding atom. Used by +%% route_session/2 to map the optional value of a Session-Id to +%% node(). +-define(NODE_TABLE, diameter_dist_node). + +%% Maps a diameter:service_name() to a node() that has called attach/1 +%% to declare its willingness to handle incoming requests for the +%% service. Use by route_session/2 in case the optional value mapping +%% has failed. +-define(SERVICE_TABLE, diameter_dist_service). + +-define(B(A), atom_to_binary(A, utf8)). +-define(ORCOND(List), list_to_tuple(['orelse', false | List])). +-define(HASH(T), erlang:phash2(T, 16#100000000)). + +%% spawn_local/2 +%% +%% Callback that is equivalent to an options list. That is, the +%% following are equivalent when passed as options to +%% diameter:add_transport/2. +%% +%% {spawn_opt, Opts} +%% {spawn_opt, {diameter_dist, spawn_local, [Opts]}} + +-spec spawn_local(ReqT :: request(), Opts :: list()) + -> pid(). + +spawn_local(ReqT, Opts) -> + spawn_opt(diameter_traffic, request, [ReqT], Opts). + +%% spawn_local/1 + +spawn_local(ReqT) -> + spawn_local(ReqT, []). + +%% route_session/2 +%% +%% Callback that maps the Session-Id of an incoming request to a +%% handler node. +%% +%% With an options list, maps an id whose optional value is the name +%% of a connected node to the same node, to handle the case that the +%% session id has been returned from diameter:session_id/1; otherwise +%% to a node that has called diameter_dist:attach/1 using the +%% consistent hashing provided by hash/3, or to the local node() if a +%% session id could not be extracted or there are no attached nodes. A +%% handler process is spawned on the selected node using +%% erlang:spawn_opt/4. +%% +%% Different behaviour can be configured by supplying an options map +%% of the following form: +%% +%% #{search => non_neg_integer(), +%% id => [binary()], +%% default => discard | local | mfa(), +%% dispatch => list() | mfa()} +%% +%% The search member limits the number of AVPs that are examined in +%% the message (from the front), to avoid searching entire message in +%% case it's known that peers follow RFC 6733's recommendation that +%% Session-Id be placed at the head of a message. The default is to +%% search the entire message. +%% +%% The id member restricts the optional value mapping to session ids +%% whose DiamterIdentity is one of those specified. Set this to the +%% list of Diameter identities advertised by the service in question +%% (typically one) to ensure that only locally generated session ids +%% are mapped; or to the empty list to disable the mapping. +%% +%% The default member determines where to handle a message whose +%% Session-Id isn't found or whose optional value isn't mapped to the +%% name of a connected node. The atom local says the local node, an +%% MFA is invoked on Session-Id | false, the name of the diameter +%% service, and the message binary, and should return either a node() +%% or false to discard the message. Defaults to {diameter_dist, hash, []}. +%% +%% The dispatch member determines how the pid() of the request handler +%% process is retrieved. An MFA is applied to a previously selected +%% node(), and the module, function, and arguments list to apply in +%% the handler process to handle the request, the MFA being supplied +%% by diameter, and returns pid() | discard. A list is equivalent to +%% {erlang, spawn_opt, []}. Defaults to []. +%% +%% This can be used with search = 0 to route on something other than +%% Session-Id, but this is probably no simpler than just implementing +%% an own spawn_opt callback. (Except with the default dispatch possibly.) +%% +%% Note that if the peer is also implemented with OTP diameter and +%% generating session ids with diameter:session_id/1 then +%% route_session/2 can map an optional value to a local node that +%% happens to have the same name as one of the peer's nodes. This +%% could lead to an uneven distribution; for example, if the peer +%% nodes are a subset of the local nodes. In practice, it's typically +%% known if it's peers or the local node originating sessions; if the +%% former then setting id = [] disables the optional value mapping, if +%% the latter then setting default = local disables the hashing. +-spec route_session(ReqT :: request(), Opts) + -> discard + | pid() + when Opts :: pos_integer() %% aka #{search => N} + | list() %% aka #{dispatch => Opts} + | #{search => non_neg_integer(), %% limit number of examined AVPs + id => [binary()], %% restrict optional value map on DiamIdent + default => local %% handle locally + | discard + | mfa(), %% return node() | false + dispatch => list() %% spawn options + | mfa()}. %% (Node, M, F, A) -> pid() | discard + +route_session(ReqT, Opts) -> + {_, Bin} = Info = diameter_traffic:request_info(ReqT), + Sid = session_id(avps(Bin), search(Opts)), + Node = default(node_of_session_id(Sid, Opts), Sid, Opts, Info), + dispatch(Node, ReqT, dispatch(Opts)). + +%% avps/1 + +avps(<<_:20/binary, Bin/binary>>) -> + Bin; + +avps(_) -> + false. + +%% dispatch/3 + +dispatch(false, _, _) -> + discard; + +dispatch(Node, ReqT, {M,F,A}) -> + apply(M, F, [Node, diameter_traffic, request, [ReqT] | A]); + +dispatch(Node, ReqT, Opts) -> + spawn_opt(Node, diameter_traffic, request, [ReqT], Opts). + +%% route_session/1 + +route_session(ReqT) -> + route_session(ReqT, []). + +%% node_of_session_id/2 +%% +%% Return the node name encoded as optional value in a Session-Id, +%% assuming the id has been created with diameter:session_id/0. Lookup +%% the node name to ensure we don't convert arbitrary binaries to +%% atom. + +node_of_session_id([Id, _, _, Bin], #{id := Ids}) -> + lists:member(Id, Ids) andalso nodemap(Bin); + +node_of_session_id([_, _, _, Bin], _) -> + nodemap(Bin); + +node_of_session_id(_, _) -> + false. + +%% nodemap/1 + +nodemap(Bin) -> + try + ets:lookup_element(?NODE_TABLE, Bin, 2) + catch + error: badarg -> false + end. + +%% session_id/2 + +session_id(_, 0) -> %% give up + false; + +%% Session-Id = Command Code 263, V-bit = 0. +session_id(<<263:32, 0:1, _:7, Len:24, _/binary>> = Bin, _) -> + case Bin of + <<Avp:Len/binary, _/binary>> -> + <<_:8/binary, Sid/binary>> = Avp, + split(Sid); + _ -> + false + end; + +%% Jump to the next AVP. This is potentially costly for a message with +%% many AVPs and no Session-Id, which an attacker is prone to send. +%% 8.8 or RFC 6733 says that Session-Id SHOULD (but not MUST) appear +%% immediately following the Diameter Header, so there is no +%% guarantee. +session_id(<<_:40, Len:24, _/binary>> = Bin, N) -> + Pad = (4 - (Len rem 4)) rem 4, + case Bin of + <<_:Len/binary, _:Pad/binary, Rest/binary>> -> + session_id(Rest, if N == infinity -> N; true -> N-1 end); + _ -> + false + end; + +session_id(_, _) -> + false. + +%% split/1 +%% +%% Split a Session-Id at no more than three semicolons: the optional +%% value (if any) follows the third. binary:split/2 does better than +%% matching character by character, especially when the pattern is +%% compiled. + +split(Bin) -> + split(3, Bin, pattern()). + +%% split/3 + +split(0, Bin, _) -> + [Bin]; + +split(N, Bin, Pattern) -> + [H|T] = binary:split(Bin, Pattern), + [H | case T of + [] -> + T; + [Rest] -> + split(N-1, Rest, Pattern) + end]. + +%% pattern/0 +%% +%% Since this is being called in a watchdog process, compile the +%% pattern once and maintain it in the process dictionary. + +pattern() -> + case get(?MODULE) of + undefined -> + CP = binary:compile_pattern(<<$;>>), %% tuple + put(?MODULE, CP), + CP; + CP -> + CP + end. + +%% dispatch/1 + +dispatch(#{} = Opts) -> + maps:get(dispatch, Opts, []); + +dispatch(Opts) + when is_list(Opts) -> + Opts; + +dispatch(_) -> + []. + +%% search/1 +%% +%% Bound number of AVPs examined when looking for Session-Id. + +search(#{search := N}) + when is_integer(N), 0 =< N -> + N; + +search(N) + when is_integer(N), 0 =< N -> + N; + +search(_) -> + infinity. + +%% default/3 +%% +%% Choose a node when Session-Id lookup has failed. + +default(false, _, #{default := discard}, _) -> + false; + +default(false, _, #{default := local}, _) -> + node(); + +default(false, Sid, #{default := {M,F,A}}, Info) -> + {ServiceName, Bin} = Info, + apply(M, F, [Sid, ServiceName, Bin | A]); %% node() | false + +default(false, Sid, _, Info) -> %% aka {?MODULE, hash, []} + {ServiceName, Bin} = Info, + hash(Sid, ServiceName, Bin); + +default(Node, _, _, _) -> + Node. + +%% =========================================================================== + +%% hash/3 +%% +%% Consistent hashing of Session-Id to an attached node, or the local +%% node if Session-Id = false or no attached nodes. + +hash(Sid, ServiceName, _) -> + case false /= Sid andalso attached(ServiceName) of + [_|_] = Nodes -> + hash(Sid, Nodes); + _ -> + node() + end. + +%% hash/2 +%% +%% Consistent hashing on arbitrary key/values. Returns false if the +%% list is empty. + +%% No key or no values. +hash(_, []) -> + false; + +%% Not much choice. +hash(_, [Value]) -> + Value; + +%% Hash on a circle and choose the closest predecessor. +hash(Key, Values) -> + Hash = ?HASH(Key), + tl(lists:foldl(fun(V,A) -> + choose(Hash, [?HASH({Key, V}) | V], A) + end, + false, %% < list() + Values)). + +%% choose/3 + +choose(Hash, [Hash1 | _] = T, [Hash2 | _]) + when Hash1 =< Hash, Hash < Hash2 -> + T; + +choose(Hash, [Hash1 | _], [Hash2 | _] = T) + when Hash2 =< Hash, Hash < Hash1 -> + T; + +choose(_, T1, T2) -> + max(T1, T2). + +%% =========================================================================== + +%% attach/1 +%% +%% Register the local node as a handler of incoming requests for the +%% specified services when using the route_session/2 spawn_opt +%% callback. + +attach(ServiceNames) -> + abcast({attach, node(), ServiceNames}). + +%% detach/1 +%% +%% Deregister the local node as a handler of incoming requests. + +detach(ServiceNames) -> + abcast({detach, node(), ServiceNames}). + +%% abcast/1 + +abcast(T) -> + gen_server:abcast([node() | nodes()], ?SERVER, T), + ok. + +%% attached/1 + +attached(ServiceName) -> + try + ets:lookup_element(?SERVICE_TABLE, ServiceName, 2) + catch + error: badarg -> [] + end. + +%% cast/2 + +cast(Node, T) -> + gen_server:cast({?SERVER, Node}, T). + +%% attach/2 + +attach(Node, S) -> + case sets:to_list(S) of + [] -> + ok; + Services -> + cast(Node, {attach, node(), Services}) + end. + +%% =========================================================================== + +start_link() -> + gen_server:start_link({local, ?SERVER}, ?MODULE, _Args = [], _Opts = []). + +%% init/1 +%% +%% Maintain [node() | nodes()] in a table that maps from binary-valued +%% names, so we can lookup the corresponding atoms rather than convert +%% binaries that aren't necessarily node names. + +init([]) -> + ets:new(?NODE_TABLE, [set, named_table]), + ets:new(?SERVICE_TABLE, [bag, named_table]), + ok = net_kernel:monitor_nodes(true, [{node_type, visible}, + nodedown_reason]), + ets:insert(?NODE_TABLE, [{?B(N), N} || N <- [node() | nodes()]]), + abcast({attach, node()}), + {ok, sets:new()}. + +%% handle_call/3 + +handle_call(_, _From, S) -> + {reply, nok, S}. + +%% handle_cast/2 + +%% Remote node is asking which services the local node wants to handle. +handle_cast({attach, Node}, S) + when Node /= node() -> + attach(Node, S), + {noreply, S}; + +%% Node wants to handle incoming requests ... +handle_cast({attach, Node, ServiceNames}, S) -> + ets:insert(?SERVICE_TABLE, [{N, Node} || N <- ServiceNames]), + {noreply, case node() of + Node -> + sets:union(S, sets:from_list(ServiceNames)); + _ -> + S + end}; + +%% ... or not. +handle_cast({detach, Node, ServiceNames}, S) -> + ets:select_delete(?SERVICE_TABLE, [{{'$1', Node}, + [?ORCOND([{'==', '$1', {const, N}} + || N <- ServiceNames])], + [true]}]), + {noreply, case node() of + Node -> + sets:subtract(S, sets:from_list(ServiceNames)); + _ -> + S + end}; + +handle_cast(_, S) -> + {noreply, S}. + +%% handle_info/2 + +handle_info({nodeup, Node, _}, S) -> + ets:insert(?NODE_TABLE, {?B(Node), Node}), + cast(Node, {attach, node()}), %% ask which services remote node handles + attach(Node, S), %% say which service local node handles + {noreply, S}; + +handle_info({nodedown, Node, _}, S) -> + ets:delete(?NODE_TABLE, ?B(Node)), + ets:select_delete(?SERVICE_TABLE, [{{'_', Node}, [], [true]}]), + {noreply, S}; + +handle_info(_, S) -> + {noreply, S}. + +%% terminate/2 + +terminate(_, _) -> + ok. + +%% code_change/3 + +%% Old code inadvertently monitored all nodes: start a new +%% subscription and remove the old one. +code_change(_OldVsn, State, "2.2") -> + ok = net_kernel:monitor_nodes(true, [{node_type, visible}, + nodedown_reason]), + ok = net_kernel:monitor_nodes(false, [{node_type, all}, + nodedown_reason]), + {ok, State}; + +code_change(_OldVsn, State, _Extra) -> + {ok, State}. |