Perl in a Nutshell, 2nd Edition

Client Connections

On the client side, the next step is to connect with a server at a particular port and host. To do this, the client uses the connect call. connect requires the socket filehandle as its first argument. The second argument is a data structure containing the port and hostname that together specify the address. The Socket package provides the sockaddr_in function to create this structure for Internet addresses and the sockaddr_un function for Unix domain addresses.

The sockaddr_in function takes a port number for its first argument and a 32-bit IP address for the second argument. The 32-bit address is formed from the inet_aton function found in the Socket package. This function takes either a hostname (e.g., www.oreilly.com) or a dotted-decimal string (e.g., 207.54.2.25) and returns the corresponding 32-bit structure.

Continuing with the previous example, a call to connect could look like this:

my $dest = sockaddr_in (80, inet_aton('www.oreilly.com'));
connect (SH, $dest) || die $!;

This call attempts to establish a network connection to the specified server and port. If successful, it returns true. Otherwise, it returns false and dies with the error in $!.

Assuming that the connect call has completed successfully and a connection has been established, there are a number of functions we can use to write to and read from the filehandle. For example, the send function sends data to a socket:

$data = "Hello";
send (FH, $data);

The print function allows a wider variety of ...