183 lines
5.0 KiB
Erlang
183 lines
5.0 KiB
Erlang
% Internal SCCP link database keeping
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% (C) 2011 by Harald Welte <laforge@gnumonks.org>
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%
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% All Rights Reserved
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%
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% This program is free software; you can redistribute it and/or modify
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% it under the terms of the GNU Affero General Public License as
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% published by the Free Software Foundation; either version 3 of the
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% License, or (at your option) any later version.
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%
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% This program is distributed in the hope that it will be useful,
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% but WITHOUT ANY WARRANTY; without even the implied warranty of
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% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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% GNU General Public License for more details.
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%
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% You should have received a copy of the GNU Affero General Public License
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% along with this program. If not, see <http://www.gnu.org/licenses/>.
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-module(sccp_links).
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-behaviour(gen_server).
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% gen_fsm callbacks
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-export([init/1, handle_call/3, handle_cast/2, handle_info/2,
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terminate/2, code_change/3]).
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% our published API
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-export([start_link/0]).
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% client functions, may internally talk to our sccp_user server
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-export([register_linkset/3, unregister_linkset/1]).
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-export([register_link/3, unregister_link/2, set_link_state/3]).
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-export([get_pid_for_link/2]).
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-record(slink, {
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key, % {linkset_name, sls}
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name,
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linkset_name,
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sls,
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user_pid,
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state
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}).
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-record(slinkset, {
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name,
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local_pc,
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remote_pc,
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user_pid,
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state,
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links
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}).
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-record(su_state, {
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linkset_tbl,
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link_tbl
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}).
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% initialization code
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start_link() ->
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gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).
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init(_Arg) ->
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LinksetTbl = ets:new(sccp_linksets, [ordered_set,
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{keypos, #slinkset.name}]),
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% create a named table so we can query without reference directly
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% within client/caller process
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LinkTbl = ets:new(sccp_link_table, [ordered_set, named_table,
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{keypos, #slink.key}]),
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{ok, #su_state{linkset_tbl = LinksetTbl, link_tbl = LinkTbl}}.
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% client side API
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% all write operations go through gen_server:call(), as only the ?MODULE
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% process has permission to modify the table content
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register_linkset(LocalPc, RemotePc, Name) ->
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gen_server:call(?MODULE, {register_linkset, {LocalPc, RemotePc, Name}}).
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unregister_linkset(Name) ->
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gen_server:call(?MODULE, {unregister_linkset, {Name}}).
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register_link(LinksetName, Sls, Name) ->
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gen_server:call(?MODULE, {register_link, {LinksetName, Sls, Name}}).
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unregister_link(LinksetName, Sls) ->
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gen_server:call(?MODULE, {unregister_link, {LinksetName, Sls}}).
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set_link_state(LinksetName, Sls, State) ->
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gen_server:call(?MODULE, {set_link_state, {LinksetName, Sls, State}}).
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% the lookup functions can directly use the ets named_table from within
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% the client process, no need to go through a synchronous IPC
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get_pid_for_link(LinksetName, Sls) ->
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case ets:lookup(sccp_link_table, {LinksetName, Sls}) of
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[#slink{user_pid = Pid}] ->
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% FIXME: check the link state
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{ok, Pid};
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_ ->
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{error, no_such_link}
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end.
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% server side code
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handle_call({register_linkset, {LocalPc, RemotePc, Name}},
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{FromPid, _FromRef}, S) ->
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#su_state{linkset_tbl = Tbl} = S,
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Ls = #slinkset{local_pc = LocalPc, remote_pc = RemotePc,
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name = Name, user_pid = FromPid},
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case ets:insert_new(Tbl, Ls) of
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false ->
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{reply, {error, ets_insert}, S};
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_ ->
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% FIXME: We need to trap the user Pid for EXIT
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% in order to automatically remove any links/linksets if
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% the user process dies
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{reply, ok, S}
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end;
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handle_call({unregister_linkset, {Name}}, {FromPid, _FromRef}, S) ->
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#su_state{linkset_tbl = Tbl} = S,
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ets:delete(Tbl, Name),
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{reply, ok, S};
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handle_call({register_link, {LsName, Sls, Name}},
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{FromPid, _FromRef}, S) ->
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#su_state{linkset_tbl = LinksetTbl, link_tbl = LinkTbl} = S,
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% check if linkset actually exists
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case ets:lookup(LinksetTbl, LsName) of
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[#slinkset{}] ->
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Link = #slink{name = Name, sls = Sls,
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user_pid = FromPid, key = {LsName, Sls}},
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case ets:insert_new(LinkTbl, Link) of
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false ->
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{reply, {error, link_exists}, S};
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_ ->
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% FIXME: We need to trap the user Pid for EXIT
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% in order to automatically remove any links if
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% the user process dies
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{reply, ok, S}
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end;
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_ ->
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{reply, {error, no_such_linkset}, S}
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end;
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handle_call({unregister_link, {LsName, Sls}}, {FromPid, _FromRef}, S) ->
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#su_state{link_tbl = LinkTbl} = S,
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ets:delete(LinkTbl, {LsName, Sls}),
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{reply, ok, S};
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handle_call({set_link_state, {LsName, Sls, State}}, {FromPid, _}, S) ->
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#su_state{link_tbl = LinkTbl} = S,
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case ets:lookup(LinkTbl, {LsName, Sls}) of
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[] ->
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{reply, {error, no_such_link}, S};
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[Link] ->
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NewLink = Link#slink{state = State},
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ets:insert(LinkTbl, NewLink),
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{reply, ok, S}
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end.
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handle_cast(Info, S) ->
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error_logger:error_report(["unknown handle_cast",
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{module, ?MODULE},
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{info, Info}, {state, S}]),
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{noreply, S}.
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handle_info(Info, S) ->
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error_logger:error_report(["unknown handle_info",
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{module, ?MODULE},
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{info, Info}, {state, S}]),
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{noreply, S}.
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terminate(Reason, _S) ->
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io:format("terminating ~p with reason ~p", [?MODULE, Reason]),
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ok.
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code_change(_OldVsn, State, _Extra) ->
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{ok, State}.
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