tbf: Begin to add some structure to the tbf code

The TBF should use the IMSI to identify a block flow but all
handling is spread across the entire code. Start to clean this
up by moving relevant code into the tbf file. Afterwards one
can clean up and add more internal structure.

1 files changed, 160 insertions, 0 deletions

diff --git a/src/tbf.cpp b/src/tbf.cpp
new file mode 100644
index 00000000..816fdb86
--- /dev/null
+++ b/src/tbf.cpp
@@ -0,0 +1,160 @@
+/* Copied from gprs_bssgp_pcu.cpp
+ *
+ * Copyright (C) 2012 Ivan Klyuchnikov
+ * Copyright (C) 2013 by Holger Hans Peter Freyther
+ *
+ * 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 <tbf.h>
+#include <gprs_rlcmac.h>
+#include <gprs_debug.h>
+
+extern "C" {
+#include <osmocom/core/msgb.h>
+}
+
+#include <errno.h>
+#include <string.h>
+
+/**
+ * TODO: split into unit test-able parts...
+ */
+int tbf_handle(struct gprs_rlcmac_bts *bts,
+		const uint32_t tlli, const char *imsi,
+		const uint8_t ms_class, const uint16_t pdu_delay_csec,
+		const uint8_t *data, const uint16_t len)
+{
+	struct gprs_rlcmac_tbf *tbf;
+	int8_t tfi; /* must be signed */
+
+	/* check for existing TBF */
+	if ((tbf = tbf_by_tlli(tlli, GPRS_RLCMAC_DL_TBF))) {
+		LOGP(DRLCMAC, LOGL_INFO, "TBF: APPEND TFI: %u TLLI: 0x%08x\n", tbf->tfi, tbf->tlli);
+		if (tbf->state == GPRS_RLCMAC_WAIT_RELEASE) {
+			LOGP(DRLCMAC, LOGL_DEBUG, "TBF in WAIT RELEASE state "
+				"(T3193), so reuse TBF\n");
+			memcpy(tbf->llc_frame, data, len);
+			tbf->llc_length = len;
+			memset(&tbf->dir.dl, 0, sizeof(tbf->dir.dl)); /* reset
+								rlc states */
+			tbf->state_flags &= GPRS_RLCMAC_FLAG_TO_MASK; /* keep
+				to flags */
+			tbf->state_flags &= ~(1 << GPRS_RLCMAC_FLAG_CCCH);
+			if (!tbf->ms_class && ms_class)
+				tbf->ms_class = ms_class;
+			tbf_update(tbf);
+			gprs_rlcmac_trigger_downlink_assignment(tbf, tbf, NULL);
+		} else {
+			/* the TBF exists, so we must write it in the queue
+			 * we prepend lifetime in front of PDU */
+			struct timeval *tv;
+			struct msgb *llc_msg = msgb_alloc(len + sizeof(*tv),
+				"llc_pdu_queue");
+			if (!llc_msg)
+				return -ENOMEM;
+			tv = (struct timeval *)msgb_put(llc_msg, sizeof(*tv));
+
+			uint16_t delay_csec;
+			if (bts->force_llc_lifetime)
+				delay_csec = bts->force_llc_lifetime;
+			else
+				delay_csec = pdu_delay_csec;
+			/* keep timestap at 0 for infinite delay */
+			if (delay_csec != 0xffff) {
+				/* calculate timestamp of timeout */
+				gettimeofday(tv, NULL);
+				tv->tv_usec += (delay_csec % 100) * 10000;
+				tv->tv_sec += delay_csec / 100;
+				if (tv->tv_usec > 999999) {
+					tv->tv_usec -= 1000000;
+					tv->tv_sec++;
+				}
+			}
+			memcpy(msgb_put(llc_msg, len), data, len);
+			msgb_enqueue(&tbf->llc_queue, llc_msg);
+			/* set ms class for updating TBF */
+			if (!tbf->ms_class && ms_class)
+				tbf->ms_class = ms_class;
+		}
+	} else {
+		uint8_t trx, ta, ss;
+		int8_t use_trx;
+		struct gprs_rlcmac_tbf *old_tbf;
+		int rc;
+
+		/* check for uplink data, so we copy our informations */
+		tbf = tbf_by_tlli(tlli, GPRS_RLCMAC_UL_TBF);
+		if (tbf && tbf->dir.ul.contention_resolution_done
+		 && !tbf->dir.ul.final_ack_sent) {
+			use_trx = tbf->trx;
+			ta = tbf->ta;
+			ss = 0;
+			old_tbf = tbf;
+		} else {
+			use_trx = -1;
+			/* we already have an uplink TBF, so we use that TA */
+			if (tbf)
+				ta = tbf->ta;
+			else {
+				/* recall TA */
+				rc = recall_timing_advance(tlli);
+				if (rc < 0) {
+					LOGP(DRLCMAC, LOGL_NOTICE, "TA unknown"
+						", assuming 0\n");
+					ta = 0;
+				} else
+					ta = rc;
+			}
+			ss = 1; /* PCH assignment only allows one timeslot */
+			old_tbf = NULL;
+		}
+
+		// Create new TBF (any TRX)
+		tfi = tfi_find_free(bts, GPRS_RLCMAC_DL_TBF, &trx, use_trx);
+		if (tfi < 0) {
+			LOGP(DRLCMAC, LOGL_NOTICE, "No PDCH resource\n");
+			/* FIXME: send reject */
+			return -EBUSY;
+		}
+		/* set number of downlink slots according to multislot class */
+		tbf = tbf_alloc(bts, tbf, GPRS_RLCMAC_DL_TBF, tfi, trx, ms_class,
+			ss);
+		if (!tbf) {
+			LOGP(DRLCMAC, LOGL_NOTICE, "No PDCH ressource\n");
+			/* FIXME: send reject */
+			return -EBUSY;
+		}
+		tbf->tlli = tlli;
+		tbf->tlli_valid = 1;
+		tbf->ta = ta;
+
+		LOGP(DRLCMAC, LOGL_DEBUG, "TBF: [DOWNLINK] START TFI: %d TLLI: 0x%08x \n", tbf->tfi, tbf->tlli);
+
+		/* new TBF, so put first frame */
+		memcpy(tbf->llc_frame, data, len);
+		tbf->llc_length = len;
+
+		/* trigger downlink assignment and set state to ASSIGN.
+		 * we don't use old_downlink, so the possible uplink is used
+		 * to trigger downlink assignment. if there is no uplink,
+		 * AGCH is used. */
+		gprs_rlcmac_trigger_downlink_assignment(tbf, old_tbf, imsi);
+	}
+
+	/* store IMSI for debugging purpose */
+	strncpy(tbf->meas.imsi, imsi, sizeof(tbf->meas.imsi) - 1);
+	return 0;
+}