client: add features to generate and parse codec information
The current implementation does not support any way to influence the
codec that is negotiated via SDP or LCO. The client statically
negotitates AMR on an invalid payload type number. Also we ignore
any codec information in the responses.
- Add struct members to allow setting of user defined codec information.
- Add struct members to retrieve parsed codec info from responses.
- Add code to generate codec information in SDP
- Add code to parse SDP codec info in MGCP responses
Change-Id: I78e72d41b73acfcb40599a0ff4823f17c3642059
Related: OS#2728
Related: OS#3334
diff --git a/src/libosmo-mgcp-client/mgcp_client.c b/src/libosmo-mgcp-client/mgcp_client.c
index e054593..00b52f8 100644
--- a/src/libosmo-mgcp-client/mgcp_client.c
+++ b/src/libosmo-mgcp-client/mgcp_client.c
@@ -36,6 +36,150 @@
#include <unistd.h>
#include <string.h>
+/* Codec descripton for dynamic payload types (SDP) */
+static const struct value_string codec_table[] = {
+ { CODEC_PCMU_8000_1, "PCMU/8000/1" },
+ { CODEC_GSM_8000_1, "GSM/8000/1" },
+ { CODEC_PCMA_8000_1, "PCMA/8000/1" },
+ { CODEC_G729_8000_1, "G729/8000/1" },
+ { CODEC_GSMEFR_8000_1, "GSM-EFR/8000/1" },
+ { CODEC_GSMHR_8000_1, "GSM-HR-08/8000/1" },
+ { CODEC_AMR_8000_1, "AMR/8000/1" },
+ { CODEC_AMRWB_16000_1, "AMR-WB/16000/1" },
+ { 0, NULL },
+};
+
+/* Get encoding name from a full codec string e,g.
+ * ("CODEC/8000/2" => returns "CODEC") */
+static char *extract_codec_name(const char *str)
+{
+ static char buf[64];
+ unsigned int i;
+
+ if (!str)
+ return NULL;
+
+ /* FIXME osmo_strlcpy */
+ osmo_strlcpy(buf, str, sizeof(buf));
+
+ for (i = 0; i < strlen(buf); i++) {
+ if (buf[i] == '/')
+ buf[i] = '\0';
+ }
+
+ return buf;
+}
+
+/*! Map a string to a codec.
+ * \ptmap[in] str input string (e.g "GSM/8000/1", "GSM/8000" or "GSM")
+ * \returns codec that corresponds to the given string representation. */
+enum mgcp_codecs map_str_to_codec(const char *str)
+{
+ unsigned int i;
+ char *codec_name;
+ char str_buf[64];
+
+ osmo_strlcpy(str_buf, extract_codec_name(str), sizeof(str_buf));
+
+ for (i = 0; i < ARRAY_SIZE(codec_table); i++) {
+ codec_name = extract_codec_name(codec_table[i].str);
+ if (!codec_name)
+ continue;
+ if (strcmp(codec_name, str_buf) == 0)
+ return codec_table[i].value;
+ }
+
+ return -1;
+}
+
+/* Check the ptmap for illegal mappings */
+static int check_ptmap(struct ptmap *ptmap)
+{
+ /* Check if there are mappings that leave the IANA assigned dynamic
+ * payload type range. Under normal conditions such mappings should
+ * not occur */
+
+ /* Its ok to have a 1:1 mapping in the statically defined
+ * range, this won't hurt */
+ if (ptmap->codec == ptmap->pt)
+ return 0;
+
+ if (ptmap->codec < 96 || ptmap->codec > 127)
+ goto error;
+ if (ptmap->pt < 96 || ptmap->pt > 127)
+ goto error;
+
+ return 0;
+error:
+ LOGP(DLMGCP, LOGL_ERROR,
+ "ptmap contains illegal mapping: codec=%u maps to pt=%u\n",
+ ptmap->codec, ptmap->pt);
+ return -1;
+}
+
+/*! Map a codec to a payload type.
+ * \ptmap[in] payload pointer to payload type map with specified payload types.
+ * \ptmap[in] ptmap_len length of the payload type map.
+ * \ptmap[in] codec the codec for which the payload type should be looked up.
+ * \returns assigned payload type */
+unsigned int map_codec_to_pt(struct ptmap *ptmap, unsigned int ptmap_len,
+ enum mgcp_codecs codec)
+{
+ unsigned int i;
+
+ /*! Note: If the payload type map is empty or the codec is not found
+ * in the map, then a 1:1 mapping is performed. If the codec falls
+ * into the statically defined range or if the mapping table isself
+ * tries to map to the statically defined range, then the mapping
+ * is also ignored and a 1:1 mapping is performed instead. */
+
+ /* we may return the codec directly since enum mgcp_codecs directly
+ * corresponds to the statićally assigned payload types */
+ if (codec < 96 || codec > 127)
+ return codec;
+
+ for (i = 0; i < ptmap_len; i++) {
+ /* Skip illegal map entries */
+ if (check_ptmap(ptmap) == 0 && ptmap->codec == codec)
+ return ptmap->pt;
+ ptmap++;
+ }
+
+ /* If nothing is found, do not perform any mapping */
+ return codec;
+}
+
+/*! Map a payload type to a codec.
+ * \ptmap[in] payload pointer to payload type map with specified payload types.
+ * \ptmap[in] ptmap_len length of the payload type map.
+ * \ptmap[in] payload type for which the codec should be looked up.
+ * \returns codec that corresponds to the specified payload type */
+enum mgcp_codecs map_pt_to_codec(struct ptmap *ptmap, unsigned int ptmap_len,
+ unsigned int pt)
+{
+ unsigned int i;
+
+ /*! Note: If the payload type map is empty or the payload type is not
+ * found in the map, then a 1:1 mapping is performed. If the payload
+ * type falls into the statically defined range or if the mapping
+ * table isself tries to map to the statically defined range, then
+ * the mapping is also ignored and a 1:1 mapping is performed
+ * instead. */
+
+ /* See also note in map_codec_to_pt() */
+ if (pt < 96 || pt > 127)
+ return pt;
+
+ for (i = 0; i < ptmap_len; i++) {
+ if (check_ptmap(ptmap) == 0 && ptmap->pt == pt)
+ return ptmap->codec;
+ ptmap++;
+ }
+
+ /* If nothing is found, do not perform any mapping */
+ return pt;
+}
+
/*! Initalize MGCP client configuration struct with default values.
* \param[out] conf Client configuration.*/
void mgcp_client_conf_init(struct mgcp_client_conf *conf)
@@ -178,22 +322,114 @@
return true;
}
-/* Parse a line like "m=audio 16002 RTP/AVP 98" */
-static int mgcp_parse_audio_port(struct mgcp_response *r, const char *line)
+/* Parse a line like "m=audio 16002 RTP/AVP 98", extract port and payload types */
+static int mgcp_parse_audio_port_pt(struct mgcp_response *r, char *line)
{
- if (sscanf(line, "m=audio %hu",
- &r->audio_port) != 1)
- goto response_parse_failure;
+ char *pt_str;
+ unsigned int pt;
+ unsigned int count = 0;
+ unsigned int i;
+ /* Extract port information */
+ if (sscanf(line, "m=audio %hu", &r->audio_port) != 1)
+ goto response_parse_failure_port;
if (r->audio_port == 0)
- goto response_parse_failure;
+ goto response_parse_failure_port;
+ /* Extract payload types */
+ line = strstr(line, "RTP/AVP ");
+ if (!line)
+ goto exit;
+
+ pt_str = strtok(line, " ");
+ while (1) {
+ /* Do not allow excessive payload types */
+ if (count > ARRAY_SIZE(r->codecs))
+ goto response_parse_failure_pt;
+
+ pt_str = strtok(NULL, " ");
+ if (!pt_str)
+ break;
+ pt = atoi(pt_str);
+
+ /* Do not allow duplicate payload types */
+ for (i = 0; i < count; i++)
+ if (r->codecs[i] == pt)
+ goto response_parse_failure_pt;
+
+ /* Note: The payload type we store may not necessarly match
+ * the codec types we have defined in enum mgcp_codecs. To
+ * ensure that the end result only contains codec types which
+ * match enum mgcp_codecs, we will go through afterwards and
+ * remap the affected entries with the inrofmation we learn
+ * from rtpmap */
+ r->codecs[count] = pt;
+ count++;
+ }
+
+ r->codecs_len = count;
+
+exit:
return 0;
-response_parse_failure:
+response_parse_failure_port:
LOGP(DLMGCP, LOGL_ERROR,
- "Failed to parse MGCP response header (audio port)\n");
+ "Failed to parse SDP parameter port (%s)\n", line);
return -EINVAL;
+
+response_parse_failure_pt:
+ LOGP(DLMGCP, LOGL_ERROR,
+ "Failed to parse SDP parameter payload types (%s)\n", line);
+ return -EINVAL;
+}
+
+/* Parse a line like "m=audio 16002 RTP/AVP 98", extract port and payload types */
+static int mgcp_parse_audio_ptime_rtpmap(struct mgcp_response *r, const char *line)
+{
+ unsigned int pt;
+ char codec_resp[64];
+ unsigned int codec;
+
+
+ if (strstr(line, "ptime")) {
+ if (sscanf(line, "a=ptime:%u", &r->ptime) != 1)
+ goto response_parse_failure_ptime;
+ } else if (strstr(line, "rtpmap")) {
+ if (sscanf(line, "a=rtpmap:%d %63s", &pt, codec_resp) == 2) {
+ /* The MGW may assign an own payload type in the
+ * response if the choosen codec falls into the IANA
+ * assigned dynamic payload type range (96-127).
+ * Normally the MGW should obey the 3gpp payload type
+ * assignments, which are fixed, so we likely wont see
+ * anything unexpected here. In order to be sure that
+ * we will now check the codec string and if the result
+ * does not match to what is IANA / 3gpp assigned, we
+ * will create an entry in the ptmap table so we can
+ * lookup later what has been assigned. */
+ codec = map_str_to_codec(codec_resp);
+ if (codec != pt) {
+ if (r->ptmap_len < ARRAY_SIZE(r->ptmap)) {
+ r->ptmap[r->ptmap_len].pt = pt;
+ r->ptmap[r->ptmap_len].codec = codec;
+ r->ptmap_len++;
+ } else
+ goto response_parse_failure_rtpmap;
+ }
+
+ } else
+ goto response_parse_failure_rtpmap;
+ }
+
+ return 0;
+
+response_parse_failure_ptime:
+ LOGP(DLMGCP, LOGL_ERROR,
+ "Failed to parse SDP parameter, invalid ptime (%s)\n", line);
+ return -EINVAL;
+response_parse_failure_rtpmap:
+ LOGP(DLMGCP, LOGL_ERROR,
+ "Failed to parse SDP parameter, invalid rtpmap (%s)\n", line);
+ return -EINVAL;
}
/* Parse a line like "c=IN IP4 10.11.12.13" */
@@ -253,6 +489,7 @@
int rc;
char *data;
char *data_ptr;
+ int i;
/* Since this functions performs a destructive parsing, we create a
* local copy of the body data */
@@ -277,8 +514,13 @@
return -EINVAL;
switch (line[0]) {
+ case 'a':
+ rc = mgcp_parse_audio_ptime_rtpmap(r, line);
+ if (rc)
+ goto exit;
+ break;
case 'm':
- rc = mgcp_parse_audio_port(r, line);
+ rc = mgcp_parse_audio_port_pt(r, line);
if (rc)
goto exit;
break;
@@ -293,6 +535,10 @@
}
}
+ /* See also note in mgcp_parse_audio_port_pt() */
+ for (i = 0; i < r->codecs_len; i++)
+ r->codecs[i] = map_pt_to_codec(r->ptmap, r->ptmap_len, r->codecs[i]);
+
rc = 0;
exit:
talloc_free(data);
@@ -813,6 +1059,119 @@
#define MGCP_AUEP_MANDATORY (MGCP_MSG_PRESENCE_ENDPOINT)
#define MGCP_RSIP_MANDATORY 0 /* none */
+/* Helper function for mgcp_msg_gen(): Add LCO information to MGCP message */
+static int add_lco(struct msgb *msg, struct mgcp_msg *mgcp_msg)
+{
+ unsigned int i;
+ int rc = 0;
+ const char *codec;
+ unsigned int pt;
+
+ rc += msgb_printf(msg, "L:");
+
+ if (mgcp_msg->ptime)
+ rc += msgb_printf(msg, " p:%u,", mgcp_msg->ptime);
+
+ if (mgcp_msg->codecs_len) {
+ rc += msgb_printf(msg, " a:");
+ for (i = 0; i < mgcp_msg->codecs_len; i++) {
+ pt = mgcp_msg->codecs[i];
+ codec = get_value_string_or_null(codec_table, pt);
+
+ /* Note: Use codec descriptors from enum mgcp_codecs
+ * in mgcp_client only! */
+ OSMO_ASSERT(codec);
+ rc += msgb_printf(msg, "%s", extract_codec_name(codec));
+ if (i < mgcp_msg->codecs_len - 1)
+ rc += msgb_printf(msg, ";");
+ }
+ rc += msgb_printf(msg, ",");
+ }
+
+ rc += msgb_printf(msg, " nt:IN\r\n");
+
+ return rc;
+}
+
+/* Helper function for mgcp_msg_gen(): Add SDP information to MGCP message */
+static int add_sdp(struct msgb *msg, struct mgcp_msg *mgcp_msg, struct mgcp_client *mgcp)
+{
+ unsigned int i;
+ int rc = 0;
+ char local_ip[INET_ADDRSTRLEN];
+ const char *codec;
+ unsigned int pt;
+
+ /* Add separator to mark the beginning of the SDP block */
+ rc += msgb_printf(msg, "\r\n");
+
+ /* Add SDP protocol version */
+ rc += msgb_printf(msg, "v=0\r\n");
+
+ /* Determine local IP-Address */
+ if (osmo_sock_local_ip(local_ip, mgcp->actual.remote_addr) < 0) {
+ LOGP(DLMGCP, LOGL_ERROR,
+ "Could not determine local IP-Address!\n");
+ msgb_free(msg);
+ return -2;
+ }
+
+ /* Add owner/creator (SDP) */
+ rc += msgb_printf(msg, "o=- %x 23 IN IP4 %s\r\n",
+ mgcp_msg->call_id, local_ip);
+
+ /* Add session name (none) */
+ rc += msgb_printf(msg, "s=-\r\n");
+
+ /* Add RTP address and port */
+ if (mgcp_msg->audio_port == 0) {
+ LOGP(DLMGCP, LOGL_ERROR,
+ "Invalid port number, can not generate MGCP message\n");
+ msgb_free(msg);
+ return -2;
+ }
+ if (strlen(mgcp_msg->audio_ip) <= 0) {
+ LOGP(DLMGCP, LOGL_ERROR,
+ "Empty ip address, can not generate MGCP message\n");
+ msgb_free(msg);
+ return -2;
+ }
+ rc += msgb_printf(msg, "c=IN IP4 %s\r\n", mgcp_msg->audio_ip);
+
+ /* Add time description, active time (SDP) */
+ rc += msgb_printf(msg, "t=0 0\r\n");
+
+ rc += msgb_printf(msg, "m=audio %u RTP/AVP", mgcp_msg->audio_port);
+ for (i = 0; i < mgcp_msg->codecs_len; i++) {
+ pt = map_codec_to_pt(mgcp_msg->ptmap, mgcp_msg->ptmap_len, mgcp_msg->codecs[i]);
+ rc += msgb_printf(msg, " %u", pt);
+
+ }
+ rc += msgb_printf(msg, "\r\n");
+
+ for (i = 0; i < mgcp_msg->codecs_len; i++) {
+ pt = map_codec_to_pt(mgcp_msg->ptmap, mgcp_msg->ptmap_len, mgcp_msg->codecs[i]);
+
+ /* Note: Only dynamic payload type from the range 96-127
+ * require to be explained further via rtpmap. All others
+ * are implcitly definedby the number in m=audio */
+ if (pt >= 96 && pt <= 127) {
+ codec = get_value_string_or_null(codec_table, mgcp_msg->codecs[i]);
+
+ /* Note: Use codec descriptors from enum mgcp_codecs
+ * in mgcp_client only! */
+ OSMO_ASSERT(codec);
+
+ rc += msgb_printf(msg, "a=rtpmap:%u %s\r\n", pt, codec);
+ }
+ }
+
+ if (mgcp_msg->ptime)
+ rc += msgb_printf(msg, "a=ptime:%u\r\n", mgcp_msg->ptime);
+
+ return rc;
+}
+
/*! Generate an MGCP message
* \param[in] mgcp MGCP client descriptor.
* \param[in] mgcp_msg Message description
@@ -823,7 +1182,8 @@
uint32_t mandatory_mask;
struct msgb *msg = msgb_alloc_headroom(4096, 128, "MGCP tx");
int rc = 0;
- char local_ip[INET_ADDRSTRLEN];
+ int rc_sdp;
+ bool use_sdp = false;
msg->l2h = msg->data;
msg->cb[MSGB_CB_MGCP_TRANS_ID] = trans_id;
@@ -902,9 +1262,17 @@
rc += msgb_printf(msg, "I: %s\r\n", mgcp_msg->conn_id);
}
- /* Add local connection options */
- if (mgcp_msg->verb == MGCP_VERB_CRCX)
- rc += msgb_printf(msg, "L: p:20, a:AMR, nt:IN\r\n");
+ /* Using SDP makes sense when a valid IP/Port combination is specifiec,
+ * if we do not know this information yet, we fall back to LCO */
+ if (mgcp_msg->presence & MGCP_MSG_PRESENCE_AUDIO_IP
+ && mgcp_msg->presence & MGCP_MSG_PRESENCE_AUDIO_PORT)
+ use_sdp = true;
+
+ /* Add local connection options (LCO) */
+ if (!use_sdp
+ && (mgcp_msg->verb == MGCP_VERB_CRCX
+ || mgcp_msg->verb == MGCP_VERB_MDCX))
+ rc += add_lco(msg, mgcp_msg);
/* Add mode */
if (mgcp_msg->presence & MGCP_MSG_PRESENCE_CONN_MODE)
@@ -912,52 +1280,15 @@
msgb_printf(msg, "M: %s\r\n",
mgcp_client_cmode_name(mgcp_msg->conn_mode));
- /* Add SDP body */
- if (mgcp_msg->presence & MGCP_MSG_PRESENCE_AUDIO_IP
- && mgcp_msg->presence & MGCP_MSG_PRESENCE_AUDIO_PORT) {
-
- /* Add separator to mark the beginning of the SDP block */
- rc += msgb_printf(msg, "\r\n");
-
- /* Add SDP protocol version */
- rc += msgb_printf(msg, "v=0\r\n");
-
- /* Determine local IP-Address */
- if (osmo_sock_local_ip(local_ip, mgcp->actual.remote_addr) < 0) {
- LOGP(DLMGCP, LOGL_ERROR,
- "Could not determine local IP-Address!\n");
- msgb_free(msg);
+ /* Add session description protocol (SDP) */
+ if (use_sdp
+ && (mgcp_msg->verb == MGCP_VERB_CRCX
+ || mgcp_msg->verb == MGCP_VERB_MDCX)) {
+ rc_sdp = add_sdp(msg, mgcp_msg, mgcp);
+ if (rc_sdp == -2)
return NULL;
- }
-
- /* Add owner/creator (SDP) */
- rc += msgb_printf(msg, "o=- %x 23 IN IP4 %s\r\n",
- mgcp_msg->call_id, local_ip);
-
- /* Add session name (none) */
- rc += msgb_printf(msg, "s=-\r\n");
-
- /* Add RTP address and port */
- if (mgcp_msg->audio_port == 0) {
- LOGP(DLMGCP, LOGL_ERROR,
- "Invalid port number, can not generate MGCP message\n");
- msgb_free(msg);
- return NULL;
- }
- if (strlen(mgcp_msg->audio_ip) <= 0) {
- LOGP(DLMGCP, LOGL_ERROR,
- "Empty ip address, can not generate MGCP message\n");
- msgb_free(msg);
- return NULL;
- }
- rc += msgb_printf(msg, "c=IN IP4 %s\r\n", mgcp_msg->audio_ip);
-
- /* Add time description, active time (SDP) */
- rc += msgb_printf(msg, "t=0 0\r\n");
-
- rc +=
- msgb_printf(msg, "m=audio %u RTP/AVP 255\r\n",
- mgcp_msg->audio_port);
+ else
+ rc += rc_sdp;
}
if (rc != 0) {