sdp: refactoring sdp parser/generator
move SDP generator function write_response_sdp() from mgcp_protocol.c
to mgcp_sdp.c and use msgb_printf() instead of snprintf()
move prototypes for mgcp_parse_sdp_data() and mgcp_set_audio_info()
to mgcp_sdp.h
change parameter list of mgcp_parse_sdp_data() so that it takes the
rtp conn directly, rather than struct mgcp_rtp_end.
add doxygen comments to all public functions
Change-Id: I9f88c93872ff913bc211f560b26901267f577324
diff --git a/src/libosmo-mgcp/mgcp_sdp.c b/src/libosmo-mgcp/mgcp_sdp.c
index 7568351..e6bf9c2 100644
--- a/src/libosmo-mgcp/mgcp_sdp.c
+++ b/src/libosmo-mgcp/mgcp_sdp.c
@@ -20,6 +20,7 @@
*
*/
+#include <osmocom/core/msgb.h>
#include <osmocom/mgcp/mgcp.h>
#include <osmocom/mgcp/mgcp_internal.h>
#include <osmocom/mgcp/mgcp_msg.h>
@@ -38,6 +39,12 @@
int channels;
};
+/*! Set codec configuration depending on payload type and codec name.
+ * \param[in] ctx talloc context.
+ * \param[out] codec configuration (caller provided memory).
+ * \param[in] payload_type codec type id (e.g. 3 for GSM, -1 when undefined).
+ * \param[in] audio_name audio codec name (e.g. "GSM/8000/1").
+ * \returns 0 on success, -1 on failure. */
int mgcp_set_audio_info(void *ctx, struct mgcp_rtp_codec *codec,
int payload_type, const char *audio_name)
{
@@ -107,7 +114,7 @@
return 0;
}
-void codecs_initialize(void *ctx, struct sdp_rtp_map *codecs, int used)
+static void codecs_initialize(void *ctx, struct sdp_rtp_map *codecs, int used)
{
int i;
@@ -137,7 +144,8 @@
}
}
-void codecs_update(void *ctx, struct sdp_rtp_map *codecs, int used, int payload, char *audio_name)
+static void codecs_update(void *ctx, struct sdp_rtp_map *codecs, int used,
+ int payload, const char *audio_name)
{
int i;
@@ -163,7 +171,9 @@
LOGP(DLMGCP, LOGL_ERROR, "Unconfigured PT(%d) with %s\n", payload, audio_name);
}
-int is_codec_compatible(struct mgcp_endpoint *endp, struct sdp_rtp_map *codec)
+/* Check if the codec matches what is set up in the trunk config */
+static int is_codec_compatible(const struct mgcp_endpoint *endp,
+ const struct sdp_rtp_map *codec)
{
char *bts_codec;
char audio_codec[64];
@@ -182,7 +192,17 @@
return strcasecmp(audio_codec, codec->codec_name) == 0;
}
-int mgcp_parse_sdp_data(struct mgcp_endpoint *endp, struct mgcp_rtp_end *rtp, struct mgcp_parse_data *p)
+/*! Analyze SDP input string.
+ * \param[in] endp trunk endpoint.
+ * \param[out] conn associated rtp connection.
+ * \param[out] caller provided memory to store the parsing results.
+ * \returns 0 on success, -1 on failure.
+ *
+ * Note: In conn (conn->end) the function returns the packet duration,
+ * the rtp port and the rtcp port */
+int mgcp_parse_sdp_data(const struct mgcp_endpoint *endp,
+ struct mgcp_conn_rtp *conn,
+ struct mgcp_parse_data *p)
{
struct sdp_rtp_map codecs[10];
int codecs_used = 0;
@@ -191,7 +211,13 @@
int i;
int codecs_assigned = 0;
void *tmp_ctx = talloc_new(NULL);
+ struct mgcp_rtp_end *rtp;
+ OSMO_ASSERT(endp);
+ OSMO_ASSERT(conn);
+ OSMO_ASSERT(p);
+
+ rtp = &conn->end;
memset(&codecs, 0, sizeof(codecs));
for_each_line(line, p->save) {
@@ -304,3 +330,73 @@
return codecs_assigned > 0;
}
+/*! Generate SDP response string.
+ * \param[in] endp trunk endpoint.
+ * \param[in] conn associated rtp connection.
+ * \param[out] sdp msg buffer to append resulting SDP string data.
+ * \param[in] addr IPV4 address string (e.g. 192.168.100.1).
+ * \returns 0 on success, -1 on failure. */
+int mgcp_write_response_sdp(const struct mgcp_endpoint *endp,
+ const struct mgcp_conn_rtp *conn, struct msgb *sdp,
+ const char *addr)
+{
+ const char *fmtp_extra;
+ const char *audio_name;
+ int payload_type;
+ int rc;
+
+ OSMO_ASSERT(endp);
+ OSMO_ASSERT(conn);
+ OSMO_ASSERT(sdp);
+ OSMO_ASSERT(addr);
+
+ /* FIXME: constify endp and conn args in get_net_donwlink_format_cb() */
+ endp->cfg->get_net_downlink_format_cb((struct mgcp_endpoint *)endp,
+ &payload_type, &audio_name,
+ &fmtp_extra,
+ (struct mgcp_conn_rtp *)conn);
+
+ rc = msgb_printf(sdp,
+ "v=0\r\n"
+ "o=- %u 23 IN IP4 %s\r\n"
+ "s=-\r\n"
+ "c=IN IP4 %s\r\n"
+ "t=0 0\r\n", conn->conn->id, addr, addr);
+
+ if (rc < 0)
+ goto buffer_too_small;
+
+ if (payload_type >= 0) {
+ rc = msgb_printf(sdp, "m=audio %d RTP/AVP %d\r\n",
+ conn->end.local_port, payload_type);
+ if (rc < 0)
+ goto buffer_too_small;
+
+ if (audio_name && endp->tcfg->audio_send_name) {
+ rc = msgb_printf(sdp, "a=rtpmap:%d %s\r\n",
+ payload_type, audio_name);
+
+ if (rc < 0)
+ goto buffer_too_small;
+ }
+
+ if (fmtp_extra) {
+ rc = msgb_printf(sdp, "%s\r\n", fmtp_extra);
+
+ if (rc < 0)
+ goto buffer_too_small;
+ }
+ }
+ if (conn->end.packet_duration_ms > 0 && endp->tcfg->audio_send_ptime) {
+ rc = msgb_printf(sdp, "a=ptime:%u\r\n",
+ conn->end.packet_duration_ms);
+ if (rc < 0)
+ goto buffer_too_small;
+ }
+
+ return 0;
+
+buffer_too_small:
+ LOGP(DLMGCP, LOGL_ERROR, "SDP messagebuffer too small\n");
+ return -1;
+}