From c9e972a26a5e76d95b00a55dd9ea55da0d173028 Mon Sep 17 00:00:00 2001
From: Sean Bright <sean.bright@gmail.com>
Date: Tue, 26 Sep 2017 11:55:29 -0400
Subject: [PATCH] res_rtp_asterisk: Trim trailing byte off of SDES packet
This could have been fixed by subtracting 1 from the final value of
'len' but the way the packet was being constructed was confusing so I
took the opportunity to (I think) make it more clear.
We were sending 1 extra byte at the end of the SDES RTCP packet which
caused Chrome to complain (in its debug log):
Too little data (1 byte) remaining in buffer to parse
RTCP header (4 bytes).
We now send the correct number of bytes.
Change-Id: I9dcf087cdaf97da0374ae0acb7d379746a71e81b
---
res/res_rtp_asterisk.c | 34 +++++++++++++++++++++++++++++-----
1 file changed, 29 insertions(+), 5 deletions(-)
diff --git a/res/res_rtp_asterisk.c b/res/res_rtp_asterisk.c
index c8cc04f96c..35cb087639 100644
--- a/res/res_rtp_asterisk.c
+++ b/res/res_rtp_asterisk.c
@@ -3771,6 +3771,7 @@ static int ast_rtcp_write_report(struct ast_rtp_instance *instance, int sr)
RAII_VAR(struct ast_json *, message_blob, NULL, ast_json_unref);
int res;
int len = 0;
+ uint16_t sdes_packet_len_bytes, sdes_packet_len_rounded;
struct timeval now;
unsigned int now_lsw;
unsigned int now_msw;
@@ -3778,7 +3779,7 @@ static int ast_rtcp_write_report(struct ast_rtp_instance *instance, int sr)
unsigned int lost_packets;
int fraction_lost;
struct timeval dlsr = { 0, };
- unsigned char bdata[512] = "";
+ unsigned char bdata[AST_UUID_STR_LEN + 128] = ""; /* More than enough */
int rate = rtp_get_rate(rtp->f.subclass.format);
int ice;
struct ast_sockaddr remote_address = { { 0, } };
@@ -3858,12 +3859,35 @@ static int ast_rtcp_write_report(struct ast_rtp_instance *instance, int sr)
put_unaligned_uint32(rtcpheader, htonl((2 << 30) | (rtcp_report->reception_report_count << 24)
| ((sr ? RTCP_PT_SR : RTCP_PT_RR) << 16) | ((len/4)-1)));
- put_unaligned_uint32(rtcpheader + len, htonl((2 << 30) | (1 << 24) | (RTCP_PT_SDES << 16) | (2 + (AST_UUID_STR_LEN / 4))));
+ sdes_packet_len_bytes =
+ 4 + /* RTCP Header */
+ 4 + /* SSRC */
+ 1 + /* Type (CNAME) */
+ 1 + /* Text Length */
+ AST_UUID_STR_LEN /* Text and NULL terminator */
+ ;
+
+ /* Round to 32 bit boundary */
+ sdes_packet_len_rounded = (sdes_packet_len_bytes + 3) & ~0x3;
+
+ put_unaligned_uint32(rtcpheader + len, htonl((2 << 30) | (1 << 24) | (RTCP_PT_SDES << 16) | ((sdes_packet_len_rounded / 4) - 1)));
put_unaligned_uint32(rtcpheader + len + 4, htonl(rtcp_report->ssrc));
- put_unaligned_uint16(rtcpheader + len + 8, htonl(0x01 << 24));
- put_unaligned_uint16(rtcpheader + len + 9, htonl(AST_UUID_STR_LEN << 24));
+ rtcpheader[len + 8] = 0x01; /* CNAME */
+ rtcpheader[len + 9] = AST_UUID_STR_LEN - 1; /* Number of bytes of text */
memcpy(rtcpheader + len + 10, rtp->cname, AST_UUID_STR_LEN);
- len += 12 + AST_UUID_STR_LEN;
+ len += 10 + AST_UUID_STR_LEN;
+
+ /* Padding - Note that we don't set the padded bit on the packet. From
+ * RFC 3550 Section 6.5:
+ *
+ * No length octet follows the null item type octet, but additional null
+ * octets MUST be included if needed to pad until the next 32-bit
+ * boundary. Note that this padding is separate from that indicated by
+ * the P bit in the RTCP header.
+ *
+ * These bytes will already be zeroed out during array initialization.
+ */
+ len += (sdes_packet_len_rounded - sdes_packet_len_bytes);
if (rtp->bundled) {
ast_rtp_instance_get_remote_address(instance, &remote_address);
--
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