133 lines
4.2 KiB
Erlang
133 lines
4.2 KiB
Erlang
% ITU-T Q.71x SCCP UDT stateful masquerading
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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_masq).
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-author('Harald Welte <laforge@gnumonks.org>').
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-include("sccp.hrl").
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-export([sccp_masq_msg/3, init/0, reset/0]).
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-compile([export_all]).
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-record(sccp_masq_rec, {
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digits_in, % list of GT digits
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digits_out, % list of GT digits
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last_access % timestamp of last usage
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}).
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% alloc + insert a new masquerade state record in our tables
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masq_alloc(DigitsOrig) ->
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{ok, Base} = application:get_env(sccp_masq_gt_base),
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{ok, Max} = application:get_env(sccp_masq_gt_max),
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masq_try_alloc(DigitsOrig, Base, Max, 0).
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masq_try_alloc(_DigitsOrig, _Base, Max, Offset) when Offset > Max ->
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undef;
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masq_try_alloc(DigitsOrig, Base, Max, Offset) ->
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Try = Base + Offset,
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EtsRet = ets:insert_new(get(sccp_masq_orig),
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#sccp_masq_rec{digits_in = DigitsOrig,
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digits_out = Try}),
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case EtsRet of
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false ->
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masq_try_alloc(DigitsOrig, Base, Max, Offset+1);
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_ ->
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ets:insert(get(sccp_masq_rev),
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#sccp_masq_rec{digits_in = Try,
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digits_out = DigitsOrig}),
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Try
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end.
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% lookup a masqerade state record
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lookup_masq_addr(orig, GtDigits) ->
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case ets:lookup(get(sccp_masq_orig), GtDigits) of
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[#sccp_masq_rec{digits_out = DigitsOut}] ->
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DigitsOut;
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_ ->
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% allocate a new masq GT
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masq_alloc(GtDigits)
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end;
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lookup_masq_addr(rev, GtDigits) ->
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case ets:lookup(get(sccp_masq_rev), GtDigits) of
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[#sccp_masq_rec{digits_out = DigitsOut}] ->
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DigitsOut;
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_ ->
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% we do not allocate entries in the reverse direction
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undef
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end.
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% Masquerade the CALLING address in first STP(G-MSC) -> HLR/VLR/MSC dir
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mangle_rx_calling(from_stp, Addr = #sccp_addr{global_title = GT}) ->
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GtOrig = GT#global_title.phone_number,
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GtReplace = lookup_masq_addr(orig, GtOrig),
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case GtReplace of
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undef ->
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io:format("SCCP MASQ: Unable to rewrite in original direction (out of GT addrs?)~n"),
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Addr;
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_ ->
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io:format("SCCP MASQ (STP->MSC) rewrite ~p->~p~n", [GtOrig, GtReplace]),
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GTout = GT#global_title{phone_number = GtReplace},
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Addr#sccp_addr{global_title = GTout}
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end;
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mangle_rx_calling(_From, Addr) ->
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Addr.
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mangle_rx_called(from_msc, Addr = #sccp_addr{global_title = GT}) ->
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GtOrig = GT#global_title.phone_number,
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GtReplace = lookup_masq_addr(rev, GtOrig),
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case GtReplace of
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undef ->
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io:format("SCCP MASQ: Unable to rewrite in original direction (unknown GT ~p)~n", [GT]),
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Addr;
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_ ->
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io:format("SCCP MASQ (MSC->STP) rewrite ~p->~p~n", [GtOrig, GtReplace]),
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GTout = GT#global_title{phone_number = GtReplace},
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Addr#sccp_addr{global_title = GTout}
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end;
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mangle_rx_called(_From, Addr) ->
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Addr.
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sccp_masq_msg(From, ?SCCP_MSGT_UDT, Msg = #sccp_msg{parameters = Opts}) ->
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CalledParty = proplists:get_value(called_party_addr, Opts),
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CalledPartyNew = mangle_rx_called(From, CalledParty),
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CallingParty = proplists:get_value(calling_party_addr, Opts),
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CallingPartyNew = mangle_rx_calling(From, CallingParty),
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Opts1 = lists:keyreplace(called_party_addr, 1, Opts,
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{called_party_addr, CalledPartyNew}),
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Opts2 = lists:keyreplace(calling_party_addr, 1, Opts1,
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{calling_party_addr, CallingPartyNew}),
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Msg#sccp_msg{parameters = Opts2};
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sccp_masq_msg(_From, _MsgType, Msg) ->
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Msg.
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init() ->
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Orig = ets:new(sccp_masq_orig, [ordered_set,
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{keypos, #sccp_masq_rec.digits_in}]),
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Rev = ets:new(sccp_masq_rev, [ordered_set,
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{keypos, #sccp_masq_rec.digits_in}]),
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put(sccp_masq_orig, Orig),
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put(sccp_masq_rev, Rev),
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ok.
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reset() ->
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io:format("SCCP MASQ: Deleting all MASQ state records~n"),
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ets:delete_all_objects(get(sccp_masq_orig)),
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ets:delete_all_objects(get(sccp_masq_rev)).
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