Dealer sending phantom message at connect

[hintjens]

Problem: when a 2.2 ROUTER gets a new connection from a 4.0.3 DEALER, an empty message arrives before anything else. This is not normal behavior.

Solution: the problem is caused by libzmq/4.0.x wrongly sending the identity message twice, to a 2.x peer. Here is what the 2.x peer receives (three frames):

-------------------
1: FF 
8: 00 00 00 00 00 00 00 06 
1: 7F 
5: 31 32 33 34 35 
-------------------
1: 06 
1: 00 
5: 31 32 33 34 35 
-------------------
1: 07 
1: 00 
6: 48 65 6C 6C 6F 00 
-------------------

The second frame is bogus.

[hintjens]

Here is a stand-alone test case, which requires CZMQ. It simulates a ZMTP V1 ROUTER peer and then dumps what it receives.

[hintjens]

Confirmed fixed. Yay! Thanks :-)

[dfszb]

Does 4.0.3 already contain this fix?
It looks like the 4.0.4 will be the first that will have it, however 4.0.4 seems to be waiting to be released.

[hintjens]

I'll make a release 4.0.4 asap then.