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Module (chicken tcp)
This module provides basic facilities for communicating over TCP sockets.
All errors related to failing network operations will raise a condition of kind (exn i/o net).
tcp-listen
- tcp-listen TCPPORT #!optional BACKLOG HOSTprocedure
Creates and returns a TCP listener object that listens for connections on TCPPORT, which should be an exact integer. BACKLOG specifies the number of maximally pending connections (and defaults to 100). If the optional argument HOST is given and not #f, then only incoming connections for the given host (or IP) are accepted.
tcp-listener?
- tcp-listener? Xprocedure
Returns #t if X is a TCP listener object, or #f otherwise.
tcp-close
- tcp-close LISTENERprocedure
Reclaims any resources associated with LISTENER.
tcp-accept
- tcp-accept LISTENERprocedure
Waits until a connection is established on the port on which LISTENER is listening and returns two values: an input- and output-port that can be used to communicate with the remote process. The current value of tcp-accept-timeout is used to determine the maximal number of milliseconds (if any) to wait until a connection is established. When a client connects any read- and write-operations on the returned ports will use the current values (at the time of the connection) of tcp-read-timeout and tcp-write-timeout, respectively, to determine the maximal number of milliseconds to wait for input/output before a timeout error is signalled.
Note: this operation and any I/O on the ports returned will not block other running threads.
tcp-accept-ready?
- tcp-accept-ready? LISTENERprocedure
Returns #t if there are any connections pending on LISTENER, or #f otherwise.
tcp-listener-port
- tcp-listener-port LISTENERprocedure
Returns the port number assigned to LISTENER (If you pass 0 to tcp-listen, then the system will choose a port-number for you).
tcp-listener-fileno
- tcp-listener-fileno LISTENERprocedure
Returns the file-descriptor associated with LISTENER.
tcp-connect
- tcp-connect HOSTNAME #!optional TCPPORTprocedure
Establishes a client-side TCP connection to the machine with the name HOSTNAME (a string) at TCPPORT (an exact integer) and returns two values: an input- and output-port for communicating with the remote process. The current value of tcp-connect-timeout is used to determine the maximal number of milliseconds (if any) to wait until the connection is established. When the connection takes place any read- and write-operations on the returned ports will use the current values (at the time of the call to tcp-connect) of tcp-read-timeout and tcp-write-timeout, respectively, to determine the maximal number of milliseconds to wait for input/output before a timeout error is signalled.
If the TCPPORT is omitted, the port is parsed from the HOSTNAME string. The format expected is HOSTNAME:PORT. The PORT can either be a string representation of an integer or a service name which is translated to an integer using the POSIX function getservbyname.
Note: any I/O on the ports returned will not block other running threads.
tcp-addresses
- tcp-addresses PORTprocedure
Returns two values for the input- or output-port PORT (which should be a port returned by either tcp-accept or tcp-connect): the IP address of the local and the remote machine that are connected over the socket associated with PORT. The returned addresses are strings in XXX.XXX.XXX.XXX notation.
tcp-port-numbers
- tcp-port-numbers PORTprocedure
Returns two values for the input- or output-port PORT (which should be a port returned by either tcp-accept or tcp-connect): the TCP port numbers of the local and the remote machine that are connected over the socket associated with PORT.
tcp-abandon-port
- tcp-abandon-port PORTprocedure
Marks the socket port PORT as abandoned. This is mainly useful to close down a port without breaking the connection.
tcp-buffer-size
- tcp-buffer-sizeparameter
Sets the size of the output buffer. By default no output-buffering for TCP output is done, but to improve performance by minimizing the number of TCP packets, buffering may be turned on by setting this parameter to an exact integer greater zero. A buffer size of zero or #f turns buffering off. The setting of this parameter takes effect at the time when the I/O ports for a particular socket are created, i.e. when tcp-connect or tcp-accept is called.
Note that since output is not immediately written to the associated socket, you may need to call flush-output, once you want the output to be transmitted. Closing the output port will flush automatically.
tcp-read-timeout
- tcp-read-timeoutparameter
Determines the timeout for TCP read operations in milliseconds. A timeout of #f disables timeout checking. The default read timeout is 60000, i.e. 1 minute. If timeout occurs while reading, a condition object of kinds (exn i/o net timeout) is thrown.
tcp-write-timeout
- tcp-write-timeoutparameter
Determines the timeout for TCP write operations in milliseconds. A timeout of #f disables timeout checking. The default write timeout is 60000, i.e. 1 minute. If timeout occurs while writing, a condition object of kinds (exn i/o net timeout) is thrown.
tcp-connect-timeout
- tcp-connect-timeoutparameter
Determines the timeout for tcp-connect operations in milliseconds. A timeout of #f disables timeout checking and is the default. If timeout occurs while trying to connect, a condition object of kinds (exn i/o net timeout) is thrown.
tcp-accept-timeout
- tcp-accept-timeoutparameter
Determines the timeout for tcp-accept operations in milliseconds. A timeout of #f disables timeout checking and is the default. If timeout occurs while waiting for connections, a condition object of kinds (exn i/o net timeout) is thrown.
Example
A very simple example follows. Say we have the two files client.scm and server.scm:
; client.scm (import (chicken io) (chicken tcp)) (define-values (i o) (tcp-connect "localhost" 4242)) (write-line "Good Bye!" o) (print (read-line i))
; server.scm (import (chicken io) (chicken tcp)) (define l (tcp-listen 4242)) (define-values (i o) (tcp-accept l)) (write-line "Hello!" o) (print (read-line i)) (close-input-port i) (close-output-port o)
% csc server.scm % csc client.scm % ./server & % ./client Good Bye! Hello!
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