SecureBitChat/securebit-chat
1
0
Fork 0
Code Issues Pull Requests Actions 12 Packages Projects Releases Wiki Activity

fix(descriptor): rebuild SDP that Firefox accepts; release v5.8.1

Browse Source 
Live cross-browser testing found three defects in the SBQ2 SDP template, all
invisible to Chrome and all fatal to Firefox.

The candidate lines omitted raddr/rport on srflx and relay candidates. RFC 8839
section 5.1 makes rel-addr and rel-port mandatory for non-host candidates even
though ICE never reads them; Chrome tolerates the omission and Firefox drops the
candidate. Relay-only connections to Firefox failed 0/8 against 8/8 for the
browser's own SDP. The STUN and TURN profiles hid it because a host pair
connected instead -- the relay candidates were never actually needed there.

The template also advertised ice-options:trickle without ever closing the
candidate set, though a descriptor is a complete one-shot set with no channel to
trickle over, and hard-coded the m= port and c= line to the 9 / 0.0.0.0 null
default candidate, which is the trickle convention for "nothing gathered yet".
Both are now correct: no trickle, an explicit a=end-of-candidates, and the most
publicly reachable candidate as the default.

All three are serializer-side and cost zero descriptor bytes; sizes are
unchanged at 98-149 bytes, QR version 6-8. Verified 48/48 across all 16
combinations of {Chrome, Firefox} squared and four network profiles, with every
relay-only pair now connecting over the relay.
This commit is contained in:
lockbitchat
2026-08-06 17:25:46 -04:00
parent 6e82cfcae2
commit fb959d7ca7
12 changed files with 207 additions and 42 deletions
Download Patch File Download Diff File Expand all files Collapse all files
tests/descriptor-sbq2.test.mjs
+64
View File
@@ -191,6 +191,70 @@ for (const [browser, fixtures] of [['chrome', chrome], ['firefox', firefox]]) {
assert.deepEqual([...re.candidates[2].addr].slice(12), [198, 51, 100, 9], 'NAT64 tail round-trips');
}
// ---------------------------------------------------------------------------
// SDP grammar conformance of the rebuilt candidate lines
//
// Regression guard. rel-addr/rel-port are mandatory for srflx/prflx/relay
// (RFC 8839 §5.1). Leaving them out is silently fine in Chrome and fatal in
// Firefox, which drops the candidate: measured 0/8 relay-only connections to
// Firefox versus 8/8 for the browser's own SDP, and invisible in the STUN and
// TURN profiles because a host pair connected instead.
// ---------------------------------------------------------------------------
{
const sdp = [
'v=0', 'm=application 9 UDP/DTLS/SCTP webrtc-datachannel',
'a=candidate:1 1 udp 2113937151 192.168.1.9 40000 typ host',
'a=candidate:2 1 udp 1677729535 203.0.113.4 40001 typ srflx raddr 192.168.1.9 rport 40000',
'a=candidate:3 1 udp 50340351 144.172.96.126 40002 typ relay raddr 203.0.113.4 rport 40001',
'a=candidate:4 1 udp 50341375 2001:db8::5 40003 typ relay',
'a=ice-ufrag:abcd', 'a=ice-pwd:0123456789abcdef01234567',
'a=fingerprint:sha-256 ' + new Array(32).fill('EE').join(':'), 'a=setup:actpass',
].join('\r\n') + '\r\n';
const out = serializeSdp(decodeDescriptor(await build(sdp, TYPE.OFFER))).sdp;
for (const line of out.split('\r\n').filter((l) => l.startsWith('a=candidate:'))) {
const type = line.split(' typ ')[1].split(' ')[0];
if (type === 'host') {
assert.ok(!line.includes('raddr'), `host candidates must not carry raddr: ${line}`);
} else {
assert.match(line, / raddr (0\.0\.0\.0|::) rport 0/, `${type} candidate needs rel-addr/rel-port: ${line}`);
}
}
// The default candidate must be a real, routable address whenever one
// exists — `m=... 9` with `c=IN IP4 0.0.0.0` is the trickle "none yet"
// form, and a descriptor is never trickle.
assert.ok(!out.includes('a=ice-options:trickle'), 'a complete candidate set must not advertise trickle');
assert.match(out, /^a=end-of-candidates$/m, 'the candidate set is explicitly closed');
// relay beats srflx beats host: the default candidate is the most publicly
// reachable one, matching what Chrome emits. Asserted on a v4-only set so
// the expected winner is unambiguous.
const v4only = [
'v=0', 'm=application 9 UDP/DTLS/SCTP webrtc-datachannel',
'a=candidate:1 1 udp 2113937151 192.168.1.9 40000 typ host',
'a=candidate:2 1 udp 1677729535 203.0.113.4 40001 typ srflx raddr 192.168.1.9 rport 40000',
'a=candidate:3 1 udp 50340351 144.172.96.126 40002 typ relay raddr 203.0.113.4 rport 40001',
'a=ice-ufrag:abcd', 'a=ice-pwd:0123456789abcdef01234567',
'a=fingerprint:sha-256 ' + new Array(32).fill('EE').join(':'), 'a=setup:actpass',
].join('\r\n') + '\r\n';
const vOut = serializeSdp(decodeDescriptor(await build(v4only, TYPE.OFFER))).sdp;
assert.match(vOut, /^m=application 40002 /m, 'm-line carries the relay port as default');
assert.match(vOut, /^c=IN IP4 144\.172\.96\.126$/m, 'c-line carries the relay address as default');
// With only an mDNS candidate there is no literal address to advertise, so
// the null form is correct — and it is what Chrome emits in that case too.
const mdnsOnly = [
'v=0', 'm=application 9 UDP/DTLS/SCTP webrtc-datachannel',
'a=candidate:1 1 udp 2113937151 7d9c00c2-bcef-48b6-9166-428899e0582e.local 40000 typ host',
'a=ice-ufrag:abcd', 'a=ice-pwd:0123456789abcdef01234567',
'a=fingerprint:sha-256 ' + new Array(32).fill('EE').join(':'), 'a=setup:actpass',
].join('\r\n') + '\r\n';
const mOut = serializeSdp(decodeDescriptor(await build(mdnsOnly, TYPE.OFFER))).sdp;
assert.match(mOut, /^m=application 9 /m);
assert.match(mOut, /^c=IN IP4 0\.0\.0\.0$/m);
}
// ---------------------------------------------------------------------------
// TCP candidates
// ---------------------------------------------------------------------------