falconia has uploaded this change for review. ( https://gerrit.osmocom.org/c/libosmo-abis/+/39626?usp=email )
Change subject: rtp2trau HR to DL: validate ToC octet of RFC 5993 ......................................................................
rtp2trau HR to DL: validate ToC octet of RFC 5993
This validation serves two purposes:
* Payloads that just happen to be 15 bytes long but aren't valid RFC 5993 should be rejected;
* Super-5993 extensions of TW-TS-002 are valid only in UL, not in DL - catch and block them.
Change-Id: Ibbaa1e1e12254eaf75a999dd1b58e2145eff158c --- M src/trau/trau_rtp_conv.c 1 file changed, 13 insertions(+), 1 deletion(-)
git pull ssh://gerrit.osmocom.org:29418/libosmo-abis refs/changes/26/39626/1
diff --git a/src/trau/trau_rtp_conv.c b/src/trau/trau_rtp_conv.c index 1114aaf..9c7ff47 100644 --- a/src/trau/trau_rtp_conv.c +++ b/src/trau/trau_rtp_conv.c @@ -664,6 +664,12 @@ case GSM_HR_BYTES: break; case GSM_HR_BYTES_RTP_RFC5993: + /* Require RFC 5993 valid frame, i.e., no BFIs etc. + * Specifically, require (F==0 && (FT==0 || FT==2)); + * masking with 0xD0 is a clever way of effecting + * this check. */ + if (data[0] & 0xD0) + return -EINVAL; data++; data_len--; break; @@ -707,6 +713,12 @@ case GSM_HR_BYTES: break; case GSM_HR_BYTES_RTP_RFC5993: + /* Require RFC 5993 valid frame, i.e., no BFIs etc. + * Specifically, require (F==0 && (FT==0 || FT==2)); + * masking with 0xD0 is a clever way of effecting + * this check. */ + if (data[0] & 0xD0) + return -EINVAL; data++; data_len--; break; @@ -1580,7 +1592,7 @@ * defined in ETSI TS 101 318 for FR, HR and EFR; the ones for FR and EFR * are also duplicated in RFC 3551. In the case of HR codec, RFC 5993 input * is also appropriate as specified in 3GPP TS 48.103 - as long as the user - * remembers that the extra header octet is ignored. + * remembers that the extra header octet is ignored beyond validation check. * * - The only correct way to implement TrFO for GSM, accepting FR/HR/EFR from * call leg A uplink in TW-TS-001 or TW-TS-002 format and generating TRAU-DL
-
falconia