1 files changed, 130 insertions, 0 deletions
diff --git a/openbsc/src/libmgcp/rtp_helper.c b/openbsc/src/libmgcp/rtp_helper.c
new file mode 100644
index 000000000..77fc4c819
--- /dev/null
+++ b/openbsc/src/libmgcp/rtp_helper.c
@@ -0,0 +1,130 @@
+/*
+ * (C) 2011 by Holger Hans Peter Freyther <zecke@selfish.org>
+ * (C) 2011 by On-Waves
+ * 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 Affero 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/>.
+ *
+ */
+
+#include <openbsc/debug.h>
+#include <openbsc/rtp_rfc.h>
+#include <openbsc/mgcp_internal.h>
+
+#include <osmocom/core/talloc.h>
+
+#include <string.h>
+
+
+struct reduced_rtp_hdr {
+	/** I will need to be inflated to the SSRC */
+	uint8_t		endp;
+	/** I will need to be inflated to both the TS and the Sequence Number */
+	uint8_t		sequence_no;
+	/**
+	 * I represent the type, you should know the size of each payload now.
+	 * I represent the number of payloads that follow
+	 */
+	uint8_t		type : 4,
+			payloads : 4;
+	uint8_t		data[0];
+} __attribute__((packed));
+
+#define msgb_put_struct(msg, str) \
+	(str *) msgb_put(msg, sizeof(str))
+
+/**
+ * I try to compress these packets into one single stream. I have various
+ * limitations. I do not support packets that jump backwards, the rtp_packets
+ * list must be properly sorted, everything else will be discarded.
+ *
+ * Also somethings like:
+ *   seq_no:1, seq_no:3, seq_no: 5
+ * will be folded into
+ *   3 payloads, Payload:1, Payload:2, Payload:3
+ *
+ * And the decoder will decode it to:
+ *   seq_no:1, seq_no:2, seq_no: 3
+ *
+ */
+int rtp_compress(struct mgcp_rtp_compr_state *state, struct msgb *msg,
+		 int endp, struct llist_head *rtp_packets)
+{
+	struct msgb *rtp, *tmp;
+	struct reduced_rtp_hdr *reduced_hdr;
+	uint16_t last_sequence = 0;
+	int count = 0;
+	uint8_t *data;
+
+	/*
+	 * sanity check if everything is a RTP packet
+	 */
+	llist_for_each_entry_safe(rtp, tmp, rtp_packets, list) {
+		struct rtp_hdr *hdr;
+		uint16_t sequence;
+
+		if (msgb_l2len(rtp) < sizeof(struct rtp_hdr)) {
+			LOGP(DMGCP, LOGL_ERROR,
+			     "Packet is too small on %d/0x%x\n", endp, endp);
+			llist_del(&rtp->list);
+			talloc_free(rtp);
+			continue;
+		}
+
+		hdr = (struct rtp_hdr *) rtp->l2h;
+		sequence = ntohs(hdr->sequence);
+		if (sequence < last_sequence && sequence != 0) {
+			LOGP(DMGCP, LOGL_ERROR, "Packet is not in sequence.\n");
+			llist_del(&rtp->list);
+			talloc_free(rtp);
+			last_sequence = sequence;
+			continue;
+		}
+
+		last_sequence = sequence;
+		count += 1;
+	}
+
+
+	if (llist_empty(rtp_packets))
+		return 0;
+
+	reduced_hdr = msgb_put_struct(msg, struct reduced_rtp_hdr);
+	reduced_hdr->endp = endp;
+	reduced_hdr->sequence_no = ++state->last_ts % UCHAR_MAX;
+	reduced_hdr->type = 0;
+	reduced_hdr->payloads = count;
+
+
+	llist_for_each_entry_safe(rtp, tmp, rtp_packets, list) {
+		struct rtp_hdr *hdr = (struct rtp_hdr *) rtp->l2h;
+		uint32_t len = msgb_l2len(rtp) - sizeof(*hdr);
+		data = msgb_put(msg, len);
+		memcpy(data, hdr->data, len);
+
+		llist_del(&rtp->list);
+		talloc_free(rtp);
+	}
+
+	return count;
+}
+
+struct llist_head rtp_decompress(struct mgcp_rtp_compr_state *state, void *ctx,
+				  struct msgb *msg)
+{
+	struct llist_head list;
+	INIT_LLIST_HEAD(&list);
+
+	return list;
+}