This was a huge work, but now UDP is usable as seen in the examples.
Instead of relying on 'connect()', just do 'sendto()' and 'recvfrom()'
as they are universal. Multicast address can only be connected in
IPv4, IPv6 wasn't working and I'm not sure the IPv4 is portable to
other platforms.
Dialer will auto-join multicast groups is the dialed address is
one. Multicast properties such as time to live (hops) and loopback can
be configured. When joining multicast groups, the local
address/interface can be configured by 'IP@IFACE' format, with
'@IFACE' being optional.
Dialers will now auto-bind, so it can receive data as dialers are
expected to be bi-directional. One can manually specify the binding
address if there is such need.
Since datagrams must be read in their full size, otherwise the
remaining bits are dropped, expose next_datagram_size_query() in both
Efl.Net.Socket.Udp and Efl.Net.Server.Udp.Client.
To finalize UDP for real we need to introduce an 'Efl_Net_Ip_Address'
structure to serve as both IPv4 and IPv6 and expose 'sendto()' and
'recvfrom()'. These will come later as this commit is already too big.
Thanks to vtorri for poiting out about close() is not the correct
socket function, we should use closesocket() instead.
Also defined SOCKET to int on Linux so we can use the same 'type' and
avoid lots of ifdef in our code. On Windows it's unsigned, thus would
cause some warnings about incorrect signed comparison.
Defined INVALID_SOCKET=-1 and SOCKET_ERROR=-1 on non-Windows platforms
so we can keep the same construct 'function() == error' and it should
work on POSIX and windows.
I cannot test these on Windows, but the situation should be improved
with this commit.
This is the initial UDP server that works similarly to the TCP one,
however under the hood it's widely different since the socket is
reused for all "clients", thus needs a new Efl.Net.Server.Udp.Client
(Efl.Net.Socket) as Efl.Net.Socket.Udp exposes the fd and options such
as 'cork', which would interfere in other clients.
The main socket will read the packets and find an existing client to
feed it. If no client exists, then it will create one if not overr
limit. Since there is no kernel-queuing as done by listen()/accept(),
the 'no reject' case will just accept the client anyway.
Next commits will improve UDP server handling with some advanced
features:
- join multicast groups
- bind to a specific interface (SO_BINDTODEVICE)
- block packets going out of local network (SO_DONTROUTE)
- specify priorities (SO_PRIORITY)
Gustavo Sverzut Barbieri