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3.6 UDP Socket Functions (7.05 and later)
Starting with Dynamic C 7.05, the UDP implementation is a true record service. It receives distinct datagrams and passes them as such to the user program. The socket I/O functions available
for TCP sockets will no longer work for UDP sockets.
3.6.1 Control Functions for UDP Sockets
These functions change the status of the socket or its I/O buffer.
• udp_close
• udp_extopen
• udp_open
3.6.2 Status Function for UDP Sockets
These functions return useful information about the status of either a socket or its I/O buffers.
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sock_bytesready
sock_dataready
sock_rbleft
sock_rbsize
sock_rbused
udp_peek
For a UDP socket, sock_bytesready() returns the number of bytes in the next datagram in
the socket buffer, or -1 if no datagrams are waiting. Note that a return of 0 is valid, since a datagram can have 0 bytes of data.
3.6.3 I/O Functions for UDP Sockets
These functions handle datagram-at-a-time I/O:
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udp_recv
udp_recvfrom
udp_send
udp_sendto
The write function, udp_sendto(), allows the remote IP address and port number to be specified. The read function, udp_recvfrom(), identifies the IP address and port number of the host
that sent the datagram. There is no longer a UDP read function that blocks until data is ready.
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TCP/IP User’s Manual