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AlCalzone / node-tradfri-client

Library to talk to IKEA Trådfri Gateways without external binaries
MIT License
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problems with firmware 1.15.34 #517

Closed justme-1968 closed 3 years ago

justme-1968 commented 3 years ago

a few of my tradfri-fhem users have noticed that the module stoped working after the latest ikea firmware update (1.15.34).

i have just noticed the same. but had not time to dig deeper.

it looks like the connection fails due to some encryption changes.

is there already a solution to this ?

AlCalzone commented 3 years ago

I'm on it

justme-1968 commented 3 years ago

perfect. thanks !

AlCalzone commented 3 years ago

Looks like there's a bug in IKEA's new DTLS implementation, specifically this part of the DTLS specification is not obeyed:

         Client                             Server
         ------                             ------
         ClientHello (seq=0)  ------>

                              <------ HelloVerifyRequest (seq=0)

         ClientHello (seq=1)  ------>
         (with cookie)

                              <------        ServerHello (seq=1)
                              <------    ServerHelloDone (seq=2)

         [Rest of handshake]

DTLS implementations maintain (at least notionally) a next_receive_seq counter. This counter is initially set to zero. When a message is received, if its sequence number matches next_receive_seq, next_receive_seq is incremented and the message is processed. If the sequence number is less than next_receive_seq, the message MUST be discarded.

The gateway sends the ServerHello with the same sequence number that the HelloVerifyRequest has, so it gets discarded, causing the handshake to fail.

AlCalzone commented 3 years ago

Will be fixed in v3.0.1 in a couple of minutes

justme-1968 commented 3 years ago

works! thanks again.