Hello,
I want to use the extended header in the rtp packets and I think I
have found a bug in pjsip.
In the function pjmedia_rtp_decode_rtp there is the following code to
calculate the offset of the payload after the extended header:
Line 169:
/* Adjust offset if RTP extension is used. */
if ((*hdr)->x) {
pjmedia_rtp_ext_hdr *ext = (pjmedia_rtp_ext_hdr*)
(((pj_uint8_t*)pkt) + offset);
offset += (pj_ntohs(ext->length) * sizeof(pj_uint32_t));
}
RFC3550 says:
The header extension contains a 16-bit length field that counts the
number of 32-bit words in the extension, excluding the four-octet
extension header (therefore zero is a valid length).
In the above code ext->length is this length field. If the extension
field is set, the offset must be at least the size of the header of
the extension (struct pjmedia_rtp_ext_hdr).
By the way: The definition of the pjmedia_rtp_ext_hdr in rtp.h should
be included into a #pragma pack(1) section to define its packing.
I have seen the problem in pjproject-1.2 and 1.3.
Anyway, thanks for the great work. I like the architecture of the
framework in general very much.
Best regards,
Thomas Falk
