neels has uploaded this change for review.

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mgcp-client: MGCP response: pass fmtp to caller

When receiving MGCP responses, so far libosmo-mgcp-client completely
ignored a=fmtp: parameters (like 'octet-align'). Add fmtp parsing to
pass the fmtp string to the caller as-is.

Since the responses so far never included the octet_aligned flags, do
not bother to parse fmtp to populate the legacy items. New callers
should use the fmtp string.

Change-Id: If8ca5c3880cad9e41b80e9d1c821439b0d7b7e23
---
M src/libosmo-mgcp-client/mgcp_client.c
1 file changed, 57 insertions(+), 2 deletions(-)

git pull ssh://gerrit.osmocom.org:29418/osmo-mgw refs/changes/05/34905/1

diff --git a/src/libosmo-mgcp-client/mgcp_client.c b/src/libosmo-mgcp-client/mgcp_client.c
index 1bbae95..6af75fd 100644
--- a/src/libosmo-mgcp-client/mgcp_client.c
+++ b/src/libosmo-mgcp-client/mgcp_client.c
@@ -377,11 +377,12 @@
 {
 	unsigned int pt;
 	unsigned int i;
-	char codec_resp[64];
+	char codec_resp[256];
 	int rc;
 
 #define A_PTIME "a=ptime:"
 #define A_RTPMAP "a=rtpmap:"
+#define A_FMTP "a=fmtp:"
 
 	if (osmo_str_startswith(line, A_PTIME)) {
 		if (sscanf(line, A_PTIME "%u", &r->ptime) != 1) {
@@ -390,7 +391,7 @@
 			return -EINVAL;
 		}
 	} else if (osmo_str_startswith(line, A_RTPMAP)) {
-		if (sscanf(line, A_RTPMAP "%d %63s", &pt, codec_resp) != 2) {
+		if (sscanf(line, A_RTPMAP "%d %255s", &pt, codec_resp) != 2) {
 			LOGP(DLMGCP, LOGL_ERROR,
 			     "Failed to parse SDP parameter, invalid rtpmap: %s\n", osmo_quote_str(line, -1));
 			return -EINVAL;
@@ -429,7 +430,44 @@
 			.codec = rc,
 		};
 		r->ptmap_len++;
+
+	} else if (osmo_str_startswith(line, A_FMTP)) {
+		if (sscanf(line, A_FMTP "%d %255s", &pt, codec_resp) != 2) {
+			LOGP(DLMGCP, LOGL_ERROR,
+			     "Failed to parse SDP parameter, invalid fmtp: %s\n", osmo_quote_str(line, -1));
+			return -EINVAL;
+		}
+
+		/* Earlier, a line like "m=audio 16002 RTP/AVP 98 112 3" established the desired order of payloads, now
+		 * enrich it with actual codec information provided by "a=rtpmap:..." entries.
+		 * For each, find the entry with the right pt number and add the info there. */
+
+		for (i = 0; i < r->ptmap_len; i++) {
+			if (r->ptmap[i].pt != pt)
+				continue;
+			OSMO_STRLCPY_ARRAY(r->ptmap[r->ptmap_len].fmtp, codec_resp);
+			return 0;
+		}
+
+		/* No entry was found. This is an error in the MGCP protocol, but let's just add another entry
+		 * anyway, to not make it look like it was never there. */
+		LOGP(DLMGCP, LOGL_ERROR,
+		     "error in MGCP message: 'a=fmtp:%u' has no matching entry in 'm=audio ... %u'\n",
+		     pt, pt);
+		if (r->ptmap_len <= ARRAY_SIZE(r->ptmap)) {
+			LOGP(DLMGCP, LOGL_ERROR,
+			     "cannot parse all codecs: can only store up to %zu rtpmap entries.\n",
+			     ARRAY_SIZE(r->ptmap));
+			return -ENOSPC;
+		}
+		r->ptmap[r->ptmap_len] = (struct ptmap){
+			.pt = pt,
+			.codec = -1,
+		};
+		OSMO_STRLCPY_ARRAY(r->ptmap[r->ptmap_len].fmtp, codec_resp);
+		r->ptmap_len++;
 	}
+
 	return 0;
 }
 

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