Re: sockets: connecting several UDP clients

Gernot Frisch wrote:


I need a socket for send_to(), don't I?

Yes, but you can use *one* SOCK_DGRAM socket for all send_to()s, independent of the IP address, as that is specified in the send_to() calls!

A-ha!
So, basically My application has a list of TCP sockets for TCP communication, and _one_ UDP socket, globally for everything.


SCOKET udp_socket = socket(AF_INET, SOCK_DGRAM,IPPROTO_UDP);
// no bind(), no nothing here

// And then I can write functions like:

UDP_sendTo(udp_socket, ulong IP, ushort port, char* message);
UDP_getFrom(udp_socket, ushort port, char* message);

Where the IP + port should be stored in a sockaddr_in for convenience.

Is that correct?

Basically: yes, apart from David's remark about bind()ing the SOCK_DGRAM port.

I think I finally understood what they all talked about "UDP is connectionless". It's just IP+port and _one_ global udp socket for the protocol.

Note that, apart from being "connectionless", UDP is also "unreliable", i.e. you cannot guarantee that a packet you send will actually reach its destination.

Josef
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These are my personal views and not those of Fujitsu Siemens Computers!
Josef Möllers (Pinguinpfleger bei FSC)
If failure had no penalty success would not be a prize (T. Pratchett)
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