sccp_links and sccp_user as registries for MTP links and local subsystems

2 files changed, 300 insertions, 0 deletions

diff --git a/src/sccp_links.erl b/src/sccp_links.erl
new file mode 100644
index 0000000..09a4321
--- /dev/null
+++ b/src/sccp_links.erl
@@ -0,0 +1,180 @@
+% Internal SCCP link database keeping
+
+% (C) 2011 by Harald Welte <laforge@gnumonks.org>
+%
+% All Rights Reserved
+%
+% This program is free software; you can redistribute it and/or modify
+% it under the terms of the GNU Affero General Public License as
+% published by the Free Software Foundation; either version 3 of the
+% License, or (at your option) any later version.
+%
+% This program is distributed in the hope that it will be useful,
+% but WITHOUT ANY WARRANTY; without even the implied warranty of
+% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+% GNU General Public License for more details.
+%
+% You should have received a copy of the GNU Affero General Public License
+% along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+-module(sccp_links).
+-behaviour(gen_server).
+
+% gen_fsm callbacks
+-export([init/1, handle_call/3, handle_cast/2, handle_info/2,
+	 terminate/2, code_change/3]).
+
+% our published API
+-export([start_link/0]).
+
+% client functions, may internally talk to our sccp_user server
+-export([register_linkset/3, unregister_linkset/1]).
+-export([register_link/3, unregister_link/2, set_link_state/3]).
+-export([get_pid_for_link/3]).
+
+-record(slink, {
+	key,		% {linkset_name, sls}
+	name,
+	linkset_name,
+	sls,
+	user_pid,
+	state
+}).
+
+-record(slinkset, {
+	name,
+	local_pc,
+	remote_pc,
+	user_pid,
+	state,
+	links
+}).
+
+-record(su_state, {
+	linkset_tbl,
+	link_tbl
+}).
+
+
+% initialization code
+
+start_link() ->
+	gen_server:start_link({local, ?MODULE}, ?MODULE, []).
+
+init(_Arg) ->
+	LinksetTbl = ets:new(sccp_linksets, [ordered_set,
+					     {keypos, #slinkset.name}]),
+
+	% create a named table so we can query without reference directly
+	% within client/caller process
+	LinkTbl = ets:new(sccp_link_table, [ordered_set, named_table,
+					    {keypos, #slink.key}]),
+	#su_state{linkset_tbl = LinksetTbl, link_tbl = LinkTbl}.
+
+% client side API
+
+% all write operations go through gen_server:call(), as only the ?MODULE
+% process has permission to modify the table content
+
+register_linkset(LocalPc, RemotePc, Name) ->
+	gen_server:call(?MODULE, {register_linkset, {LocalPc, RemotePc, Name}}).
+
+unregister_linkset(Name) ->
+	gen_server:call(?MODULE, {unregister_linkset, {Name}}).
+
+register_link(LinksetName, Sls, Name) ->
+	gen_server:call(?MODULE, {register_link, {LinksetName, Sls, Name}}).
+
+unregister_link(LinksetName, Sls) ->
+	gen_server:call(?MODULE, {unregister_link, {LinksetName, Sls}}).
+
+set_link_state(LinksetName, Sls, State) ->
+	gen_server:call(?MODULE, {set_link_state, {LinksetName, Sls, State}}).
+
+% the lookup functions can directly use the ets named_table from within
+% the client process, no need to go through a synchronous IPC
+
+get_pid_for_link(LinkTable, LinksetName, Sls) ->
+	case ets:lookup(sccp_link_table, {LinksetName, Sls}) of
+	    [#slink{user_pid = Pid}] ->	
+		% FIXME: check the link state 
+		{ok, Pid};
+	    _ ->
+		{error, no_such_link}
+	end.
+
+% server side code
+
+handle_call({register_linkset, {LocalPc, RemotePc, Name}}, From, S) ->
+	#su_state{linkset_tbl = Tbl} = S,
+	Ls = #slinkset{local_pc = LocalPc, remote_pc = RemotePc,
+		       name = Name, user_pid = From},
+	case ets:insert_new(Tbl, Ls) of
+	    false ->
+		{reply, {error, ets_insert}, S};
+	    _ ->
+		% FIXME: We need to trap the user Pid for EXIT
+		% in order to automatically remove any links/linksets if
+		% the user process dies
+		{reply, ok, S}
+	end;
+
+handle_call({unregister_linkset, {Name}}, From, S) ->
+	#su_state{linkset_tbl = Tbl} = S,
+	ets:delete(Tbl, Name),
+	{reply, ok, S};
+
+handle_call({register_link, {LsName, Sls, Name}}, From, S) ->
+	#su_state{linkset_tbl = LinksetTbl, link_tbl = LinkTbl} = S,
+	% check if linkset actually exists
+	case ets:loookup(LinksetTbl, LsName) of
+	    [#slinkset{}] ->
+		Link = #slink{name = Name, sls = Sls,
+			      user_pid = From, key = {LsName, Sls}},
+		case ets:insert_new(LinkTbl, Link) of
+		    false ->
+			{reply, {error, link_exists}, S};
+		    _ ->
+			% FIXME: We need to trap the user Pid for EXIT
+			% in order to automatically remove any links if
+			% the user process dies
+			{reply, ok, S}
+		end;
+	    _ ->
+		{reply, {error, no_such_linkset}, S}
+	end;
+
+handle_call({unregister_link, {LsName, Sls}}, From, S) ->
+	#su_state{link_tbl = LinkTbl} = S,
+	ets:delete(LinkTbl, {LsName, Sls}),
+	{reply, ok, S};
+
+handle_call({set_link_state, {LsName, Sls, State}}, From, S) ->
+	#su_state{linkset_tbl = LinksetTbl, link_tbl = LinkTbl} = S,
+	case ets:lookup(LinkTbl, {LsName, Sls}) of
+	    [] ->
+		{reply, {error, no_such_link}, S};
+	    [Link] ->
+		NewLink = Link#slink{state = State},
+		ets:insert(LinkTbl, NewLink),
+		{reply, ok, S}
+	end.
+
+handle_cast(Info, S) ->
+	error_logger:error_report(["unknown handle_cast",
+				  {module, ?MODULE},
+				  {info, Info}, {state, S}]),
+	{noreply, S}.
+
+handle_info(Info, S) ->
+	error_logger:error_report(["unknown handle_info",
+				  {module, ?MODULE},
+				  {info, Info}, {state, S}]),
+	{noreply, S}.
+
+terminate(Reason, _S) ->
+	io:format("terminating ~p with reason ~p", [?MODULE, Reason]),
+	ok.
+
+code_change(_OldVsn, State, _Extra) ->
+	{ok, State}.
diff --git a/src/sccp_user.erl b/src/sccp_user.erl
new file mode 100644
index 0000000..9404973
--- /dev/null
+++ b/src/sccp_user.erl
@@ -0,0 +1,120 @@
+% SCCP user interface procedures
+
+% (C) 2011 by Harald Welte <laforge@gnumonks.org>
+%
+% All Rights Reserved
+%
+% This program is free software; you can redistribute it and/or modify
+% it under the terms of the GNU Affero General Public License as
+% published by the Free Software Foundation; either version 3 of the
+% License, or (at your option) any later version.
+%
+% This program is distributed in the hope that it will be useful,
+% but WITHOUT ANY WARRANTY; without even the implied warranty of
+% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+% GNU General Public License for more details.
+%
+% You should have received a copy of the GNU Affero General Public License
+% along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+-module(sccp_user).
+-behaviour(gen_server).
+
+%-include_lib("osmo_ss7/osmo_util.hrl").
+%-include_lib("osmo_ss7/sccp.hrl").
+%-include_lib("osmo_ss7/mtp3.hrl").
+
+% gen_fsm callbacks
+-export([init/1, handle_call/3, handle_cast/2, handle_info/2,
+	 terminate/2, code_change/3]).
+
+% our published API
+-export([start_link/0]).
+
+% client functions, may internally talk to our sccp_user server
+-export([bind_ssn/2, unbind_ssn/2, pid_for_ssn/2, local_ssn_avail/2]).
+
+-record(scu_state, {
+	user_table
+}).
+
+-record(scu_record, {
+	ssn_pc,
+	user_pid
+}).
+
+% initialization code
+
+start_link() ->
+	gen_server:start_link({local, ?MODULE}, ?MODULE, []).
+
+init(_Arg) ->
+	UserTbl = ets:new(sccp_user_tbl, [ordered_set, named_table,
+				       {keypos, #scu_record.ssn_pc}]),
+	#scu_state{user_table = UserTbl}.
+
+% client side code
+
+bind_ssn(Ssn, Pc) ->
+	gen_server:call(?MODULE, {bind_ssn, Ssn, Pc}).
+
+unbind_ssn(Ssn, Pc) ->
+	gen_server:call(?MODULE, {unbind_ssn, Ssn, Pc}).
+
+% determine the pid registered for a given {Ssn, PC}
+pid_for_ssn(Ssn, Pc) ->
+	% as this is only a read access, we read the ets table directly
+	% rather than going through call/2
+	case ets:lookup(sccp_user_tbl, {Ssn, Pc}) of
+	    [#scu_record{user_pid = UserPid}] ->
+		{ok, UserPid};
+	    _ ->
+		{error, no_such_ssn}
+	end.
+
+local_ssn_avail(Ssn, Pc) ->
+	case pid_for_ssn(Ssn, Pc) of
+	    {ok, UserPid} ->
+		true;
+	    _ ->
+		false
+	end.
+
+% server side code 
+
+% bind a {SSN, PC} tuple to the pid of the caller
+handle_call({bind_ssn, Ssn, Pc}, From, S) ->
+	#scu_state{user_table = Tbl} = S,
+	NewRec = #scu_record{ssn_pc= {Ssn, Pc}, user_pid = From},
+	case ets:insert_new(Tbl, NewRec) of
+	    false ->
+		{reply, {error, ets_insert}, S};
+	    Error ->
+		{reply, ok, S}
+	end;
+
+% unbind a {SSN, PC} tuple from the pid of the caller
+handle_call({unbind_ssn, Ssn, Pc}, From, S) ->
+	#scu_state{user_table = Tbl} = S,
+	DelRec = #scu_record{ssn_pc= {Ssn, Pc}, user_pid = From},
+	ets:delete_object(Tbl, DelRec),
+	{reply, ok, S}.
+
+handle_cast(Info, S) ->
+	error_logger:error_report(["unknown handle_cast",
+				  {module, ?MODULE},
+				  {info, Info}, {state, S}]),
+	{noreply, S}.
+
+handle_info(Info, S) ->
+	error_logger:error_report(["unknown handle_info",
+				  {module, ?MODULE},
+				  {info, Info}, {state, S}]),
+	{noreply, S}.
+
+terminate(Reason, _S) ->
+	io:format("terminating ~p with reason ~p", [?MODULE, Reason]),
+	ok.
+
+code_change(_OldVsn, State, _Extra) ->
+	{ok, State}.