Hello,
I have moved recently from v1.4.14 to v.1.4.15, and I am now encountering some weird issue. Going back to v1.4.14 fixes my issue (v1.4.15 used through Buildroot v2018.02). Before describing the exact problem, here is my use case :
-  C API to create a client 
 
- I use callbacks API to set callbacks on logs, connect/disconnect events, publish/subscribe events and so on
- connection uses TLS (custom certificate provided to API)
- once connected, Mosquitto file descriptor is provided and integrated to an EFL main loop
Trying to establish a new connection to my broker (using the 
mosquitto_connect API), I can see that a new TCP connection is opened 
onto the broker, but it seems that no MQTT data is transfered (i.e. no 
CONNECT event), so the broker, of course, does not answer the usual 
CONNACK (observed with tcpdump).
I have made sure that the issue only
 happens in v1.4.15. Quickly taking a look on Eclipse Github, I saw no 
specific issue directly linked to this problem.
Before diving more in
 depth in this issue on mosquitto code, I would like to ask here : is 
there anyone encountering the same issue with this new mosquitto version
 ? I did not see any comment about this in the mailing list, but maybe 
the release is too young so it has not been detected yet ?
Or anyone can confirm that this new version, used as client with C API, works on its side ?
Regards