To make the whole task
of creating clients and servers easier, a socket library was developed
that encapsulates the various socket and network information functions.
Here is the same finger client using the library:
#!/usr/local/bin/perl
require "sockets.pl";
$service = "finger";
chop ($hostname = `/bin/hostname`);
$input = shift (@ARGV);
($username, $remote_host) = split (/@/, $input, 2);
unless ($remote_host) {
$remote_host = $hostname;
}
Most of the code here is the same as that used in the previous
example, with one exception. The require
command includes the sockets.pl library.
&open_connection (FINGER, $remote_host, $service)
|| die "Cannot open connection to: $remote_host", "\n";
The open_connection
library subroutine performs the following tasks:
- Check to see if the remote host is
an IP number (128.197.152.10) or an IP name
(acs.bu.edu), and perform the appropriate conversion to a packed
address string.
- Create a socket.
- Bind the socket to the current host.
- Connect the socket to the remote address and port.
- Unbuffer the socket.
Now, here is the rest of the program.
print FINGER $username, "\n";
while (<FINGER>) {
print;
}
&close_connection (FINGER);
exit (0);
The close_connection
subroutine flushes the socket so that all the remaining information
in the socket is released, and then closes it. As you can see, this
library makes the whole process of communicating with network servers
much easier. Now, let's look at a simple example that interacts
with an HTTP server.
