ms: Add GprsMs class to hold per-MS information

Currently only TBF objects are used to handle the data flow between
the MS and the SGSN. MS specific data (e.g. pending LLC frames, TLLI)
is copied between successive TBFs. If all TBFs (uplink and downlink)
are idle for some time, all information about the MS is discarded in
the PCU. This makes the implementation of some features more
difficult, e.g. proper TLLI and timing advance handling,
connection based CS selection, and proper management of multiple TBF.

This commit adds the GprsMs class that is intended to hold
information directly related to the MS and to keep references to the
active TBFs.

The class is not yet integrated with the other PCU code. A GprsMs
object container and MS specific fields (TA, CS) will be added in
later commits.

Note that calling detach_tbf() can possibly delete the MS object
depending on the callback implementation.

Ticket: #1674
Sponsored-by: On-Waves ehf

1 files changed, 182 insertions, 0 deletions

diff --git a/src/gprs_ms.cpp b/src/gprs_ms.cpp
new file mode 100644
index 00000000..db29d206
--- /dev/null
+++ b/src/gprs_ms.cpp
@@ -0,0 +1,182 @@
+/* gprs_ms.cpp
+ *
+ * Copyright (C) 2015 by Sysmocom s.f.m.c. GmbH
+ * Author: Jacob Erlbeck <jerlbeck@sysmocom.de>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * 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 General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+ */
+
+
+#include "gprs_ms.h"
+
+#include "tbf.h"
+#include "gprs_debug.h"
+
+extern "C" {
+	#include <osmocom/core/talloc.h>
+	#include <osmocom/core/utils.h>
+}
+
+extern void *tall_pcu_ctx;
+
+struct GprsMsDefaultCallback: public GprsMs::Callback {
+	virtual void ms_idle(class GprsMs *ms) {
+		delete ms;
+	}
+	virtual void ms_active(class GprsMs *) {}
+};
+
+static GprsMsDefaultCallback gprs_default_cb;
+
+
+GprsMs::Guard::Guard(GprsMs *ms) : m_ms(ms)
+{
+	if (m_ms)
+		m_ms->ref();
+}
+
+GprsMs::Guard::~Guard()
+{
+	if (m_ms)
+		m_ms->unref();
+}
+
+GprsMs::GprsMs(uint32_t tlli) :
+	m_cb(&gprs_default_cb),
+	m_ul_tbf(NULL),
+	m_dl_tbf(NULL),
+	m_tlli(tlli),
+	m_is_idle(true),
+	m_ref(0)
+{
+	LOGP(DRLCMAC, LOGL_INFO, "Creating MS object, TLLI = 0x%08x\n", tlli);
+}
+
+GprsMs::~GprsMs()
+{
+	LOGP(DRLCMAC, LOGL_INFO, "Destroying MS object, TLLI = 0x%08x\n", tlli());
+}
+
+void* GprsMs::operator new(size_t size)
+{
+	static void *tall_ms_ctx = NULL;
+	if (!tall_ms_ctx)
+		tall_ms_ctx = talloc_named_const(tall_pcu_ctx, 0, __PRETTY_FUNCTION__);
+
+	return talloc_size(tall_ms_ctx, size);
+}
+
+void GprsMs::operator delete(void* p)
+{
+	talloc_free(p);
+}
+
+void GprsMs::ref()
+{
+	m_ref += 1;
+}
+
+void GprsMs::unref()
+{
+	OSMO_ASSERT(m_ref >= 0);
+	m_ref -= 1;
+	if (m_ref == 0)
+		update_status();
+}
+
+void GprsMs::attach_tbf(struct gprs_rlcmac_tbf *tbf)
+{
+	if (tbf->direction == GPRS_RLCMAC_DL_TBF)
+		attach_dl_tbf(static_cast<gprs_rlcmac_dl_tbf *>(tbf));
+	else
+		attach_ul_tbf(static_cast<gprs_rlcmac_ul_tbf *>(tbf));
+}
+
+void GprsMs::attach_ul_tbf(struct gprs_rlcmac_ul_tbf *tbf)
+{
+	if (m_ul_tbf == tbf)
+		return;
+
+	LOGP(DRLCMAC, LOGL_INFO, "Attaching TBF to MS object, TLLI = 0x%08x, TBF = %s\n",
+		tlli(), tbf->name());
+
+	Guard guard(this);
+
+	if (m_ul_tbf)
+		detach_tbf(m_ul_tbf);
+
+	m_ul_tbf = tbf;
+}
+
+void GprsMs::attach_dl_tbf(struct gprs_rlcmac_dl_tbf *tbf)
+{
+	if (m_dl_tbf == tbf)
+		return;
+
+	LOGP(DRLCMAC, LOGL_INFO, "Attaching TBF to MS object, TLLI = 0x%08x, TBF = %s\n",
+		tlli(), tbf->name());
+
+	Guard guard(this);
+
+	if (m_dl_tbf)
+		detach_tbf(m_dl_tbf);
+
+	m_dl_tbf = tbf;
+}
+
+void GprsMs::detach_tbf(gprs_rlcmac_tbf *tbf)
+{
+	if (m_ul_tbf && tbf == static_cast<gprs_rlcmac_tbf *>(m_ul_tbf))
+		m_ul_tbf = NULL;
+	else if (m_dl_tbf && tbf == static_cast<gprs_rlcmac_tbf *>(m_dl_tbf))
+		m_dl_tbf = NULL;
+	else
+		return;
+
+	LOGP(DRLCMAC, LOGL_INFO, "Detaching TBF from MS object, TLLI = 0x%08x, TBF = %s\n",
+		tlli(), tbf->name());
+
+	update_status();
+}
+
+void GprsMs::update_status()
+{
+	if (m_ref > 0)
+		return;
+
+	if (is_idle() && !m_is_idle) {
+		m_is_idle = true;
+		m_cb->ms_idle(this);
+		/* this can be deleted by now, do not access it */
+		return;
+	}
+
+	if (!is_idle() && m_is_idle) {
+		m_is_idle = false;
+		m_cb->ms_active(this);
+	}
+}
+
+void GprsMs::set_tlli(uint32_t tlli)
+{
+	if (tlli == m_tlli)
+		return;
+
+	LOGP(DRLCMAC, LOGL_INFO,
+		"Modifying MS object, TLLI: 0x%08x -> 0x%08x\n",
+		m_tlli, tlli);
+
+	m_tlli = tlli;
+}