csd_v110: handle empty/incomplete Uplink frames gracefully

Change-Id: I7cbf868df3ba5d390cea3d529eef26d18dbe55ab
Related: OS#1572

3 files changed, 80 insertions, 3 deletions

diff --git a/src/common/csd_v110.c b/src/common/csd_v110.c
index 230a6a7d..5046d6e9 100644
--- a/src/common/csd_v110.c
+++ b/src/common/csd_v110.c
@@ -87,9 +87,14 @@ int csd_v110_rtp_encode(const struct gsm_lchan *lchan, uint8_t *rtp,
 	if (OSMO_UNLIKELY(desc->num_blocks == 0))
 		return -ENOTSUP;
 
-	/* handle empty/incomplete frames gracefully */
-	if (OSMO_UNLIKELY(data_len < (desc->num_blocks * desc->num_bits)))
-		return -ENODATA;
+	/* handle empty/incomplete Uplink frames gracefully */
+	if (OSMO_UNLIKELY(data_len < (desc->num_blocks * desc->num_bits))) {
+		/* encode N idle frames as per 3GPP TS 44.021, section 8.1.6 */
+		memset(&ra_bits[0], 0x01, sizeof(ra_bits));
+		for (unsigned int i = 0; i < desc->num_blocks; i++)
+			memset(&ra_bits[i * 80], 0x00, 8); /* alignment pattern */
+		goto ra1_ra2;
+	}
 
 	/* RA1'/RA1: convert from radio rate to an intermediate data rate */
 	for (unsigned int i = 0; i < desc->num_blocks; i++) {
@@ -117,6 +122,7 @@ int csd_v110_rtp_encode(const struct gsm_lchan *lchan, uint8_t *rtp,
 		osmo_v110_encode_frame(&ra_bits[i * 80], 80, &df);
 	}
 
+ra1_ra2:
 	/* RA1/RA2: convert from an intermediate rate to 64 kbit/s */
 	if (desc->num_blocks == 4) {
 		/* 4 * 80 bits (16 kbit/s) => 2 bits per octet */
diff --git a/tests/csd/csd_test.c b/tests/csd/csd_test.c
index f24331d3..466ff880 100644
--- a/tests/csd/csd_test.c
+++ b/tests/csd/csd_test.c
@@ -135,6 +135,17 @@ static void exec_test_case(const struct test_case *tc)
 		fprintf(stderr, "[!] Data mismatch @ %03u: D%u vs E%u\n",
 			i, data_dec[i], data_enc[i]);
 	}
+
+	fprintf(stderr, "[i] Testing '%s' (IDLE)\n", tc->name);
+
+	/* encode an idle RTP frame and print it */
+	rc = csd_v110_rtp_encode(&lchan, &rtp[0], &data_enc[0], 0);
+	fprintf(stderr, "[i] csd_v110_rtp_encode() returns %d\n", rc);
+	if (rc != RFC4040_RTP_PLEN)
+		return;
+	/* print the encoded RTP frame (16 bytes per row) */
+	for (unsigned int i = 0; i < sizeof(rtp) / 16; i++)
+		fprintf(stderr, "    %s\n", osmo_hexdump(&rtp[i * 16], 16));
 }
 
 int main(int argc, char **argv)
diff --git a/tests/csd/csd_test.err b/tests/csd/csd_test.err
index 94505dc3..b8623247 100644
--- a/tests/csd/csd_test.err
+++ b/tests/csd/csd_test.err
@@ -12,6 +12,18 @@
     ff 7f 7f 7f bf bf bf bf ff 7f 7f 7f bf ff 7f 7f 
     bf bf bf bf ff 7f 7f 7f bf bf bf bf ff 7f 7f 7f 
 [i] csd_v110_rtp_decode() returns 240
+[i] Testing 'TCH/F9.6' (IDLE)
+[i] csd_v110_rtp_encode() returns 160
+    3f 3f 3f 3f ff ff ff ff ff ff ff ff ff ff ff ff 
+    ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 
+    ff ff ff ff ff ff ff ff 3f 3f 3f 3f ff ff ff ff 
+    ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 
+    ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 
+    3f 3f 3f 3f ff ff ff ff ff ff ff ff ff ff ff ff 
+    ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 
+    ff ff ff ff ff ff ff ff 3f 3f 3f 3f ff ff ff ff 
+    ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 
+    ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 
 [i] Testing 'TCH/F4.8' (bitnum=120)
 [i] csd_v110_rtp_encode() returns 160
     7f 7f 7f 7f 7f 7f 7f 7f ff 7f ff 7f ff 7f ff 7f 
@@ -25,6 +37,18 @@
     ff 7f ff 7f ff 7f ff 7f ff ff 7f ff 7f ff 7f ff 
     ff 7f ff 7f ff 7f ff 7f ff ff 7f ff 7f ff 7f ff 
 [i] csd_v110_rtp_decode() returns 120
+[i] Testing 'TCH/F4.8' (IDLE)
+[i] csd_v110_rtp_encode() returns 160
+    7f 7f 7f 7f 7f 7f 7f 7f ff ff ff ff ff ff ff ff 
+    ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 
+    ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 
+    ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 
+    ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 
+    7f 7f 7f 7f 7f 7f 7f 7f ff ff ff ff ff ff ff ff 
+    ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 
+    ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 
+    ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 
+    ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 
 [i] Testing 'TCH/H4.8' (bitnum=240)
 [i] csd_v110_rtp_encode() returns 160
     3f 3f 3f 3f bf bf bf bf ff 7f 7f 7f bf bf bf bf 
@@ -38,6 +62,18 @@
     ff 7f 7f 7f bf bf bf bf ff 7f 7f 7f bf ff 7f 7f 
     bf bf bf bf ff 7f 7f 7f bf bf bf bf ff 7f 7f 7f 
 [i] csd_v110_rtp_decode() returns 240
+[i] Testing 'TCH/H4.8' (IDLE)
+[i] csd_v110_rtp_encode() returns 160
+    3f 3f 3f 3f ff ff ff ff ff ff ff ff ff ff ff ff 
+    ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 
+    ff ff ff ff ff ff ff ff 3f 3f 3f 3f ff ff ff ff 
+    ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 
+    ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 
+    3f 3f 3f 3f ff ff ff ff ff ff ff ff ff ff ff ff 
+    ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 
+    ff ff ff ff ff ff ff ff 3f 3f 3f 3f ff ff ff ff 
+    ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 
+    ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 
 [i] Testing 'TCH/F2.4' (bitnum=72)
 [i] csd_v110_rtp_encode() returns 160
     7f 7f 7f 7f 7f 7f 7f 7f ff 7f 7f ff ff 7f 7f ff 
@@ -51,6 +87,18 @@
     ff 7f 7f ff ff 7f 7f ff ff 7f 7f ff ff 7f 7f ff 
     ff 7f 7f ff ff 7f 7f ff ff 7f 7f ff ff 7f 7f ff 
 [i] csd_v110_rtp_decode() returns 72
+[i] Testing 'TCH/F2.4' (IDLE)
+[i] csd_v110_rtp_encode() returns 160
+    7f 7f 7f 7f 7f 7f 7f 7f ff ff ff ff ff ff ff ff 
+    ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 
+    ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 
+    ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 
+    ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 
+    7f 7f 7f 7f 7f 7f 7f 7f ff ff ff ff ff ff ff ff 
+    ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 
+    ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 
+    ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 
+    ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 
 [i] Testing 'TCH/H2.4' (bitnum=144)
 [i] csd_v110_rtp_encode() returns 160
     3f 3f 3f 3f bf 7f bf 7f bf 7f bf 7f bf 7f bf 7f 
@@ -64,3 +112,15 @@
     bf 7f bf 7f bf 7f bf 7f bf 7f bf 7f ff 3f 7f 7f 
     bf 7f bf 7f bf 7f bf 7f bf 7f bf 7f bf 7f bf 7f 
 [i] csd_v110_rtp_decode() returns 144
+[i] Testing 'TCH/H2.4' (IDLE)
+[i] csd_v110_rtp_encode() returns 160
+    3f 3f 3f 3f ff ff ff ff ff ff ff ff ff ff ff ff 
+    ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 
+    ff ff ff ff ff ff ff ff 3f 3f 3f 3f ff ff ff ff 
+    ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 
+    ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 
+    3f 3f 3f 3f ff ff ff ff ff ff ff ff ff ff ff ff 
+    ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 
+    ff ff ff ff ff ff ff ff 3f 3f 3f 3f ff ff ff ff 
+    ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 
+    ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff