SOCKLISTEN Function

FD = SOCKLISTEN(ip$, port, backlog)

Creates a listening TCP socket bound to ip$:port and starts queueing incoming connections (up to backlog). Returns a non-negative file descriptor on success, or -1 on failure.

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How to use it

• ip$ is a dotted-quad string (e.g. "10.0.2.15"). Use NETINFO$("ip") for the local address.
• port is the local TCP port to listen on.
• backlog is the maximum number of pending (not yet accepted) connections to queue.
• Accept connections with SOCKACCEPT(FD); write with SOCKWRITE, read with SOCKREAD/INSOCKET$, and close with SOCKCLOSE.

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Examples

REM Listen and handle one connection
srv = SOCKLISTEN(NETINFO$("ip"), 2000, 5)
PRINT "Socket server listening on port 2000"
REPEAT
    cli = SOCKACCEPT(srv)
    IF cli >= 0 THEN
        SOCKWRITE cli, "HELLORLD!" + CHR$(10) + CHR$(13)
        SOCKFLUSH cli
        SOCKCLOSE cli
    ENDIF
UNTIL INKEY$ <> ""
SOCKCLOSE srv

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Notes

• Binding to "0.0.0.0" (if supported) listens on all local interfaces.
• SOCKACCEPT returns a new FD for each established connection; call repeatedly to drain the queue.

See also: SOCKACCEPT · SOCKWRITE · SOCKREAD · INSOCKET$ Function$ "INSOCKET\$" · SOCKCLOSE · NETINFO$ Function$ "NETINFO\$"