OpenBTS-UMTS/Control/ControlCommon.cpp

/**@file Common-use functions for the control layer. */

/*
 * OpenBTS provides an open source alternative to legacy telco protocols and 
 * traditionally complex, proprietary hardware systems.
 *
 * Copyright 2008, 2010 Free Software Foundation, Inc.
 * Copyright 2014 Range Networks, Inc.
 *
 * This software is distributed under the terms of the GNU Affero General 
 * Public License version 3. See the COPYING and NOTICE files in the main 
 * directory for licensing information.
 *
 * This use of this software may be subject to additional restrictions.
 * See the LEGAL file in the main directory for details.
 */


#include "ControlCommon.h"
#include "TransactionTable.h"

#include <GSML3Message.h>
#include <GSML3CCMessages.h>
#include <GSML3RRMessages.h>
#include <GSML3MMMessages.h>
#include <UMTSLogicalChannel.h>

#include <SIPEngine.h>
#include <SIPInterface.h>

#include <Logger.h>
#undef WARNING


using namespace std;
using namespace Control;





// FIXME -- getMessage should return an L3Frame, not an L3Message.
// This will mean moving all of the parsing into the control layer.
// FIXME -- This needs an adjustable timeout.

GSM::L3Message* Control::getMessage(UMTS::LogicalChannel *LCH, unsigned SAPI)
{
	// FIXME -- We need to set a proper timeout here.
	unsigned timeout_ms = 20000;
	GSM::L3Frame *rcv = LCH->recv(timeout_ms,SAPI);
	if (rcv==NULL) {
		LOG(NOTICE) << "timeout";
		throw ChannelReadTimeout();
	}
	LOG(DEBUG) << "received " << *rcv;
	GSM::Primitive primitive = rcv->primitive();
	if (primitive!=GSM::DATA) {
		LOG(NOTICE) << "unexpected primitive " << primitive;
		delete rcv;
		throw UnexpectedPrimitive();
	}
	GSM::L3Message *msg = GSM::parseL3(*rcv);
	delete rcv;
	if (msg==NULL) {
		LOG(NOTICE) << "unparsed message";
		throw UnsupportedMessage();
	}
	return msg;
}






/* Resolve a mobile ID to an IMSI and return TMSI if it is assigned. */
unsigned  Control::resolveIMSI(bool sameLAI, GSM::L3MobileIdentity& mobileID, UMTS::LogicalChannel* LCH)
{
	// Returns known or assigned TMSI.
	assert(LCH);
	LOG(DEBUG) << "resolving mobile ID " << mobileID << ", sameLAI: " << sameLAI;

	// IMSI already?  See if there's a TMSI already, too.
	if (mobileID.type()==GSM::IMSIType) return gTMSITable.TMSI(mobileID.digits());

	// IMEI?  WTF?!
	// FIXME -- Should send MM Reject, cause 0x60, "invalid mandatory information".
	if (mobileID.type()==GSM::IMEIType) throw UnexpectedMessage();

	// Must be a TMSI.
	// Look in the table to see if it's one we assigned.
	unsigned TMSI = mobileID.TMSI();
	char* IMSI = NULL;
	if (sameLAI) IMSI = gTMSITable.IMSI(TMSI);
	if (IMSI) {
		// We assigned this TMSI already; the TMSI/IMSI pair is already in the table.
		mobileID = GSM::L3MobileIdentity(IMSI);
		LOG(DEBUG) << "resolving mobile ID (table): " << mobileID;
		free(IMSI);
		return TMSI;
	}
	// Not our TMSI.
	// Phones are not supposed to do this, but many will.
	// If the IMSI's not in the table, ASK for it.
	LCH->send(GSM::L3IdentityRequest(GSM::IMSIType));
	// FIXME -- This request times out on T3260, 12 sec.  See GSM 04.08 Table 11.2.
	GSM::L3Message* msg = getMessage(LCH);
	GSM::L3IdentityResponse *resp = dynamic_cast<GSM::L3IdentityResponse*>(msg);
	if (!resp) {
		if (msg) delete msg;
		throw UnexpectedMessage();
	}
	mobileID = resp->mobileID();
	LOG(INFO) << resp;
	delete msg;
	LOG(DEBUG) << "resolving mobile ID (requested): " << mobileID;
	// FIXME -- Should send MM Reject, cause 0x60, "invalid mandatory information".
	if (mobileID.type()!=GSM::IMSIType) throw UnexpectedMessage();
	// Return 0 to indicate that we have not yet assigned our own TMSI for this phone.
	return 0;
}



/* Resolve a mobile ID to an IMSI. */
void  Control::resolveIMSI(GSM::L3MobileIdentity& mobileIdentity, UMTS::LogicalChannel* LCH)
{
	// Are we done already?
	if (mobileIdentity.type()==GSM::IMSIType) return;

	// If we got a TMSI, find the IMSI.
	if (mobileIdentity.type()==GSM::TMSIType) {
		char *IMSI = gTMSITable.IMSI(mobileIdentity.TMSI());
		if (IMSI) mobileIdentity = GSM::L3MobileIdentity(IMSI);
		free(IMSI);
	}

	// Still no IMSI?  Ask for one.
	if (mobileIdentity.type()!=GSM::IMSIType) {
		LOG(NOTICE) << "MOC with no IMSI or valid TMSI.  Reqesting IMSI.";
		LCH->send(GSM::L3IdentityRequest(GSM::IMSIType));
		// FIXME -- This request times out on T3260, 12 sec.  See GSM 04.08 Table 11.2.
		GSM::L3Message* msg = getMessage(LCH);
		GSM::L3IdentityResponse *resp = dynamic_cast<GSM::L3IdentityResponse*>(msg);
		if (!resp) {
			if (msg) delete msg;
			throw UnexpectedMessage();
		}
		mobileIdentity = resp->mobileID();
		delete msg;
	}

	// Still no IMSI??
	if (mobileIdentity.type()!=GSM::IMSIType) {
		// FIXME -- This is quick-and-dirty, not following GSM 04.08 5.
		LOG(WARNING) << "MOC setup with no IMSI";
		// Cause 0x60 "Invalid mandatory information"
		LCH->send(GSM::L3CMServiceReject(GSM::L3RejectCause(0x60)));
		LCH->send(GSM::L3ChannelRelease());
		// The SIP side and transaction record don't exist yet.
		// So we're done.
		return;
	}
}