@node Networking
@comment  node-name,  next,  previous,  up
@chapter Networking
@cindex Sockets, Networking

The @code{sb-bsd-sockets} module provides a thinly disguised BSD
socket API for SBCL. Ideas have been stolen from the BSD socket API
for C and Graham Barr's IO::Socket classes for Perl.

Sockets are represented as CLOS objects, and the API naming
conventions attempt to balance between the BSD names and good lisp style.

@menu
* Sockets Overview::
* General Sockets::      Methods applicable to all sockets
* Socket Options::
* INET Domain Sockets::
* Local (Unix) Domain Sockets::
* Name Service::
@end menu

@node Sockets Overview
@section Sockets Overview

Most of the functions are modelled on the BSD socket API.  BSD sockets
are widely supported, portably @emph{(``portable'' by Unix standards, at least)}
available on a variety of systems, and documented.  There are some
differences in approach where we have taken advantage of some of the
more useful features of Common Lisp - briefly:

@itemize

@item
Where the C API would typically return -1 and set @code{errno},
@code{sb-bsd-sockets} signals an error. All the errors are subclasses
of @code{sb-bsd-sockets:socket-condition} and generally correspond one
for one with possible @code{errno} values.

@item 
We use multiple return values in many places where the C API would use
pass-by-reference values.

@item
We can often avoid supplying an explicit @emph{length} argument to
functions because we already know how long the argument is.

@item
IP addresses and ports are represented in slightly friendlier fashion
than "network-endian integers".

@end itemize

@node General Sockets
@section General Sockets

@include class-sb-bsd-sockets-socket.texinfo

@include fun-sb-bsd-sockets-socket-bind.texinfo

@include fun-sb-bsd-sockets-socket-accept.texinfo

@include fun-sb-bsd-sockets-socket-connect.texinfo

@include fun-sb-bsd-sockets-socket-peername.texinfo

@include fun-sb-bsd-sockets-socket-name.texinfo

@include fun-sb-bsd-sockets-socket-receive.texinfo

@include fun-sb-bsd-sockets-socket-listen.texinfo

@include fun-sb-bsd-sockets-socket-open-p.texinfo

@include fun-sb-bsd-sockets-socket-close.texinfo

@include fun-sb-bsd-sockets-socket-make-stream.texinfo

@include fun-sb-bsd-sockets-socket-error.texinfo

@include fun-sb-bsd-sockets-non-blocking-mode.texinfo

@node Socket Options
@section Socket Options

A subset of socket options are supported, using a fairly general
framework which should make it simple to add more as required - see
@file{SYS:CONTRIB;SB-BSD-SOCKETS:SOCKOPT.LISP} for details. The name
mapping from C is fairly straightforward: @code{SO_RCVLOWAT} becomes
@code{sockopt-receive-low-water} and @code{(setf
sockopt-receive-low-water)}.

@include fun-sb-bsd-sockets-sockopt-reuse-address.texinfo

@include fun-sb-bsd-sockets-sockopt-keep-alive.texinfo

@include fun-sb-bsd-sockets-sockopt-oob-inline.texinfo

@include fun-sb-bsd-sockets-sockopt-bsd-compatible.texinfo

@include fun-sb-bsd-sockets-sockopt-pass-credentials.texinfo

@include fun-sb-bsd-sockets-sockopt-debug.texinfo

@include fun-sb-bsd-sockets-sockopt-dont-route.texinfo

@include fun-sb-bsd-sockets-sockopt-broadcast.texinfo

@include fun-sb-bsd-sockets-sockopt-tcp-nodelay.texinfo

@node INET Domain Sockets
@section INET Domain Sockets

The TCP and UDP sockets that you know and love. Some representation
issues:

@itemize

@item
Internet addresses are represented by vectors of (unsigned-byte 8) -
viz. #(127 0 0 1). Ports are just integers: 6010. No conversion
between network- and host-order data is needed from the user of this
package.

@item
Socket addresses are represented by the two values for address and
port, so for example, (socket-connect s #(192 168 1 1) 80).

@end itemize

@include class-sb-bsd-sockets-inet-socket.texinfo

@include fun-sb-bsd-sockets-make-inet-address.texinfo

@include fun-sb-bsd-sockets-get-protocol-by-name.texinfo

@node Local (Unix) Domain Sockets
@section Local (Unix) Domain Sockets

Local domain (@code{AF_LOCAL}) sockets are also known as Unix-domain
sockets, but were renamed by POSIX presumably on the basis that they
may be available on other systems too.
                                                                                
A local socket address is a string, which is used to create a node in
the local filesystem. This means of course that they cannot be used
across a network.

@include class-sb-bsd-sockets-local-socket.texinfo

@node Name Service
@section Name Service

Presently name service is implemented by calling whatever
@code{gethostbyname(2)} uses. This may be any or all of
@file{/etc/hosts}, NIS, DNS, or something completely different.
Typically it's controlled by @file{/etc/nsswitch.conf}.
                                                                                
Direct links to the asynchronous @code{resolver(3)} routines would be
nice to have eventually, so that we can do DNS lookups in parallel
with other things

@include class-sb-bsd-sockets-host-ent.texinfo

@include fun-sb-bsd-sockets-get-host-by-name.texinfo

@include fun-sb-bsd-sockets-get-host-by-address.texinfo

@include fun-sb-bsd-sockets-host-ent-address.texinfo

@include fun-sb-bsd-sockets-name-service-error.texinfo
