libstrophe uses non-blocking sockets and the connect() syscall may
return before a TCP connection is established. This doesn't allow
to catch all possible errors synchronously and some of the errors
are handled in the event handler.
In a scenario with multiple SRV records and/or multiple IP addresses
resolution, we need to repeat connection attempt on a failure.
xmpp_sock_t resolves the above problem. It keeps resolved records and
addresses to repeat connect attempt asynchronously.
The registered callback function will be called before connect() is
called on the socket, allowing tweaking of much more than just keepalive
settings.
This deprecates xmpp_conn_set_keepalive().
Includes helper/example callback function to set default keepalive
parameters that some library users may find useful.
Const variables in prototypes don't add much value, but make the code
larger and redundant. Remove these const keywords.
Note, this doesn't apply to pointers to const memory.
@sjaeckel integrated clang-format with formal coding style. Run his
script and commit changes.
There are pros and cons of this commit.
Mixed coding style is a "broken window". A good single style simplifies
reading and writing code.
On the other hand, this is a big change which will lead to conflicts.
