[lwip-devel] [bug #58142] mDNS: RFC violation after recent changes - affecting probing

[David GIRAULT]

Follow-up Comment #2, bug #58142 (project lwip):

I just recover some capture just before my patch. See frame 239 & 241 on the
attached capture.

Frame 239 is the Probe sent by Lwip. Frame 241 is the conflicting probe sent
by the BCT. This one is should result in lwIP WIN in tiebreaking (Port is 79
is < port 80 sent by Lwip). All previous conflicting probe result in lwIP LOST
tiebreaking.

But, lwIP lost!

Frame 243, lwIP re-probe. Frame 245, BCT conflict probe that should lost. Same
for 246 & 248, the third probe & conflict.

lwIP should announce just after, but instead redo probing in 249/251/253.

lwIP announce only in Frame 256 after 3 additional probes without BCT sending
any conflict (test was already failed).


  239  63.088615 169.254.61.58 → 224.0.0.251  MDNS 197 Standard query 0x0000
ANY lwip-180.local, "QU" question ANY Cobra [938]._cobra-eci._tcp.local, "QU"
question A 169.254.61.58 AAAA fe80::f8f0:5ff:fe36:3a3c SRV 0 0 80
lwip-180.local TXT
  241  63.261466 169.254.182.99 → 224.0.0.251  MDNS 160 Standard query
0x0000 ANY CoBra [938]._cObrA-eCi._Tcp.LOcal, "QU" question SRV 0 0 79
lwip-180.local
  243  64.281103 169.254.61.58 → 224.0.0.251  MDNS 197 Standard query 0x0000
ANY lwip-180.local, "QU" question ANY Cobra [938]._cobra-eci._tcp.local, "QU"
question A 169.254.61.58 AAAA fe80::f8f0:5ff:fe36:3a3c SRV 0 0 80
lwip-180.local TXT
  245  64.480271 169.254.182.99 → 224.0.0.251  MDNS 160 Standard query
0x0000 ANY Cobra [938]._cobra-ecI._tcP.lOCAl, "QU" question SRV 0 0 79
lwip-180.local
  246  65.491614 169.254.61.58 → 224.0.0.251  MDNS 197 Standard query 0x0000
ANY lwip-180.local, "QU" question ANY Cobra [938]._cobra-eci._tcp.local, "QU"
question A 169.254.61.58 AAAA fe80::f8f0:5ff:fe36:3a3c SRV 0 0 80
lwip-180.local TXT
  248  65.710155 169.254.182.99 → 224.0.0.251  MDNS 160 Standard query
0x0000 ANY cobrA [938]._CObRa-eci._TcP.lOcaL, "QU" question SRV 0 0 79
lwip-180.local
  249  66.735742 169.254.61.58 → 224.0.0.251  MDNS 197 Standard query 0x0000
ANY lwip-180.local, "QU" question ANY Cobra [938]._cobra-eci._tcp.local, "QU"
question A 169.254.61.58 AAAA fe80::f8f0:5ff:fe36:3a3c SRV 0 0 80
lwip-180.local TXT
  251  66.979057 169.254.61.58 → 224.0.0.251  MDNS 197 Standard query 0x0000
ANY lwip-180.local, "QU" question ANY Cobra [938]._cobra-eci._tcp.local, "QU"
question A 169.254.61.58 AAAA fe80::f8f0:5ff:fe36:3a3c SRV 0 0 80
lwip-180.local TXT
  253  67.275080 169.254.61.58 → 224.0.0.251  MDNS 197 Standard query 0x0000
ANY lwip-180.local, "QU" question ANY Cobra [938]._cobra-eci._tcp.local, "QU"
question A 169.254.61.58 AAAA fe80::f8f0:5ff:fe36:3a3c SRV 0 0 80
lwip-180.local TXT
  256  67.566714 169.254.61.58 → 224.0.0.251  MDNS 358 Standard query
response 0x0000 A, cache flush 169.254.61.58 PTR, cache flush lwip-180.local
AAAA, cache flush fe80::f8f0:5ff:fe36:3a3c PTR, cache flush lwip-180.local PTR
_cobra-eci._tcp.local PTR Cobra [938]._cobra-eci._tcp.local SRV, cache flush 0
0 80 lwip-180.local TXT, cache flush
  258  68.512479 169.254.61.58 → 224.0.0.251  MDNS 358 Standard query
response 0x0000 A, cache flush 169.254.61.58 PTR, cache flush lwip-180.local
AAAA, cache flush fe80::f8f0:5ff:fe36:3a3c PTR, cache flush lwip-180.local PTR
_cobra-eci._tcp.local PTR Cobra [938]._cobra-eci._tcp.local SRV, cache flush 0
0 80 lwip-180.local TXT, cache flush



I hope this help resolving tiebreaking issue the right way.

Regards,
David

(file #48793)
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Additional Item Attachment:

File name: capture_bct2.pcap              Size:50 KB
    <https://savannah.nongnu.org/file/capture_bct2.pcap?file_id=48793>



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