add RTP support

This patch adds the initial RTP support for libosmo-netif, it's based
on Harald's RTP support available in openBSC.

I have also added a couple of example to show how our new channel
infrastructure interacts with the RTP layer.

Signed-off-by: Pablo Neira Ayuso <pablo@gnumonks.org>

1 files changed, 143 insertions, 0 deletions

diff --git a/examples/rtp-udp-test-client.c b/examples/rtp-udp-test-client.c
new file mode 100644
index 0000000..4989a6c
--- /dev/null
+++ b/examples/rtp-udp-test-client.c
@@ -0,0 +1,143 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <signal.h>
+#include <unistd.h>
+#include <arpa/inet.h>
+#include <time.h>
+
+#include <osmocom/core/linuxlist.h>
+#include <osmocom/core/talloc.h>
+#include <osmocom/core/msgb.h>
+#include <osmocom/core/logging.h>
+#include <osmocom/core/application.h>
+#include <osmocom/core/select.h>
+
+#include <osmocom/netif/rtp.h>
+#include <osmocom/netif/datagram.h>
+
+#define DRTP_TEST 0
+
+struct log_info_cat rtp_test_cat[] = {
+	[DRTP_TEST] = {
+		.name = "DRTP_TEST",
+		.description = "RTP client test",
+		.color = "\033[1;35m",
+		.enabled = 1, .loglevel = LOGL_DEBUG,
+	},
+};
+
+const struct log_info rtp_test_log_info = {
+	.filter_fn = NULL,
+	.cat = rtp_test_cat,
+	.num_cat = ARRAY_SIZE(rtp_test_cat),
+};
+
+static struct osmo_dgram_conn *conn;
+static struct osmo_rtp_handle *rtp;
+
+static int read_cb(struct osmo_dgram_conn *conn)
+{
+	struct msgb *msg;
+	int payload_type;
+
+	LOGP(DLINP, LOGL_DEBUG, "received message\n");
+
+	msg = msgb_alloc(RTP_MSGB_SIZE, "RTP/test");
+	if (msg == NULL) {
+		LOGP(DRTP_TEST, LOGL_ERROR, "cannot allocate message\n");
+		return -1;
+	}
+	if (osmo_dgram_conn_recv(conn, msg) < 0) {
+		msgb_free(msg);
+		LOGP(DRTP_TEST, LOGL_ERROR, "cannot receive message\n");
+		return -1;
+	}
+	payload_type = osmo_rtp_parse(rtp, msg);
+	if (payload_type < 0) {
+		msgb_free(msg);
+		LOGP(DRTP_TEST, LOGL_ERROR, "cannot parse RTP message\n");
+		return -1;
+	}
+
+	LOGP(DLINP, LOGL_DEBUG, "received message with RTP payload type: %d\n",
+		payload_type);
+
+	msgb_free(msg);
+	return 0;
+}
+
+void sighandler(int foo)
+{
+	LOGP(DLINP, LOGL_NOTICE, "closing RTP.\n");
+	osmo_dgram_conn_close(conn);
+	osmo_dgram_conn_destroy(conn);
+	osmo_rtp_handle_free(rtp);
+	exit(EXIT_SUCCESS);
+}
+
+static void *tall_test;
+
+int main(int argc, char *argv[])
+{
+	int i;
+	char dummy_data[RTP_PT_GSM_FULL_PAYLOAD_LEN] = {};
+
+	signal(SIGINT, sighandler);
+
+	tall_test = talloc_named_const(NULL, 1, "rtp_test");
+
+	osmo_init_logging(&rtp_test_log_info);
+	log_set_log_level(osmo_stderr_target, LOGL_DEBUG);
+
+	/*
+	 * initialize RTP stuff.
+	 */
+	rtp = osmo_rtp_handle_create(tall_test);
+	if (rtp == NULL) {
+		LOGP(DLINP, LOGL_ERROR, "creating RTP handler\n");
+		exit(EXIT_FAILURE);
+	}
+	osmo_rtp_handle_tx_set_sequence(rtp, random());
+	osmo_rtp_handle_tx_set_ssrc(rtp, random());
+	osmo_rtp_handle_tx_set_timestamp(rtp, time(NULL));
+
+	/*
+	 * initialize datagram socket.
+	 */
+
+	conn = osmo_dgram_conn_create(tall_test);
+	if (conn == NULL) {
+		fprintf(stderr, "cannot create client\n");
+		exit(EXIT_FAILURE);
+	}
+	osmo_dgram_conn_set_local_addr(conn, "127.0.0.1");
+	osmo_dgram_conn_set_local_port(conn, 20001);
+	osmo_dgram_conn_set_remote_addr(conn, "127.0.0.1");
+	osmo_dgram_conn_set_remote_port(conn, 20000);
+	osmo_dgram_conn_set_read_cb(conn, read_cb);
+
+	if (osmo_dgram_conn_open(conn) < 0) {
+		fprintf(stderr, "cannot open client\n");
+		exit(EXIT_FAILURE);
+	}
+
+	for(i=0; i<10; i++) {
+		struct msgb *msg;
+
+		msg = osmo_rtp_build(rtp, RTP_PT_GSM_FULL,
+				     RTP_PT_GSM_FULL_PAYLOAD_LEN,
+				     dummy_data, RTP_PT_GSM_FULL_DURATION);
+		if (msg == NULL) {
+			LOGP(DLINP, LOGL_ERROR, "OOM\n");
+			continue;
+		}
+		osmo_dgram_conn_send(conn, msg);
+	}
+
+	LOGP(DLINP, LOGL_NOTICE, "Entering main loop\n");
+
+	while(1) {
+		osmo_select_main(0);
+	}
+}