rtp_proxy: Simplify AMR handling
AMR frames on the MNCC interface are slightly different as they
include a single-byte payload_length indicator prior to the actual
payload. Commit 3f201ac89952b68d05c0bb6cb41932b9cd898b19 introduced
more special-case handling than required, so I'm trying to simplify
things again.
We now also use msgb_put() more consistently, i.e. always put
before actually using the data, and use the return value of msgb_put()
rather than first making assumptions about the pointer, writing to it
and then calling msgb_put().
diff --git a/openbsc/src/libtrau/rtp_proxy.c b/openbsc/src/libtrau/rtp_proxy.c
index 95729ef..9251dec 100644
--- a/openbsc/src/libtrau/rtp_proxy.c
+++ b/openbsc/src/libtrau/rtp_proxy.c
@@ -105,6 +105,9 @@
#define RTP_VERSION 2
+/* 33 for FR, all other codecs have smaller size */
+#define MAX_RTP_PAYLOAD_LEN 33
+
/* decode an rtp frame and create a new buffer with payload */
static int rtp_decode(struct msgb *msg, uint32_t callref, struct msgb **data)
{
@@ -112,7 +115,7 @@
struct gsm_data_frame *frame;
struct rtp_hdr *rtph = (struct rtp_hdr *)msg->data;
struct rtp_x_hdr *rtpxh;
- uint8_t *payload;
+ uint8_t *payload, *payload_out;
int payload_len;
int msg_type;
int x_len;
@@ -200,33 +203,31 @@
return -EINVAL;
}
- if (payload_len > 33) {
+ if (payload_len > MAX_RTP_PAYLOAD_LEN) {
DEBUGPC(DLMUX, "RTP payload too large (%d octets)\n",
payload_len);
return -EINVAL;
}
- if (rtph->payload_type == RTP_PT_AMR) {
- new_msg = msgb_alloc(sizeof(struct gsm_data_frame) + 1
- + payload_len, "GSM-DATA (AMR)");
- } else {
- new_msg = msgb_alloc(sizeof(struct gsm_data_frame)
- + payload_len, "GSM-DATA");
- }
+ /* always allocate for the maximum possible size to avoid
+ * fragmentation */
+ new_msg = msgb_alloc(sizeof(struct gsm_data_frame) +
+ MAX_RTP_PAYLOAD_LEN, "GSM-DATA (TCH)");
+
if (!new_msg)
return -ENOMEM;
- frame = (struct gsm_data_frame *)(new_msg->data);
+ frame = msgb_put(new_msg, sizeof(struct gsm_data_frame));
frame->msg_type = msg_type;
frame->callref = callref;
if (rtph->payload_type == RTP_PT_AMR) {
- frame->data[0] = payload_len;
- msgb_put(new_msg, sizeof(struct gsm_data_frame) + 1
- + payload_len);
- memcpy(frame->data + 1, payload, payload_len);
- } else {
- msgb_put(new_msg, sizeof(struct gsm_data_frame) + payload_len);
- memcpy(frame->data, payload, payload_len);
+ /* for FR/HR/EFR the length is implicit. In AMR, we
+ * need to make it explicit by using the first byte of
+ * the data[] buffer as length byte */
+ uint8_t *data0 = msgb_put(new_msg, 1);
+ *data0 = payload_len;
}
+ payload_out = msgb_put(new_msg, payload_len);
+ memcpy(payload_out, payload, payload_len);
*data = new_msg;
return 0;
@@ -256,6 +257,7 @@
struct rtp_sub_socket *rss = &rs->rtp;
struct msgb *msg;
struct rtp_hdr *rtph;
+ uint8_t *payload;
int payload_type;
int payload_len;
int duration; /* in samples */
@@ -316,21 +318,16 @@
}
}
- if (payload_len > 33) {
+ if (payload_len > MAX_RTP_PAYLOAD_LEN) {
DEBUGPC(DLMUX, "RTP payload too large (%d octets)\n",
payload_len);
return -EINVAL;
}
- if (frame->msg_type == GSM_TCH_FRAME_AMR)
- msg = msgb_alloc(sizeof(struct rtp_hdr) + payload_len,
- "RTP-GSM (AMR)");
- else
- msg = msgb_alloc(sizeof(struct rtp_hdr) + payload_len,
- "RTP-GSM");
+ msg = msgb_alloc(sizeof(struct rtp_hdr) + payload_len, "RTP-GSM");
if (!msg)
return -ENOMEM;
- rtph = (struct rtp_hdr *)msg->data;
+ rtph = (struct rtp_hdr *) msgb_put(msg, sizeof(struct rtp_hdr));
rtph->version = RTP_VERSION;
rtph->padding = 0;
rtph->extension = 0;
@@ -341,13 +338,12 @@
rtph->timestamp = htonl(rs->transmit.timestamp);
rs->transmit.timestamp += duration;
rtph->ssrc = htonl(rs->transmit.ssrc);
+
+ payload = msgb_put(msg, payload_len);
if (frame->msg_type == GSM_TCH_FRAME_AMR)
- memcpy(msg->data + sizeof(struct rtp_hdr), frame->data + 1,
- payload_len);
+ memcpy(payload, frame->data + 1, payload_len);
else
- memcpy(msg->data + sizeof(struct rtp_hdr), frame->data,
- payload_len);
- msgb_put(msg, sizeof(struct rtp_hdr) + payload_len);
+ memcpy(payload, frame->data, payload_len);
msgb_enqueue(&rss->tx_queue, msg);
rss->bfd.when |= BSC_FD_WRITE;