5.41.1. Create a server #

• Use socket function to create the socket service.

• Use bind function binds the port.

• Use listen function listens on the port.

• Use accept function to receive client requests.

5.41.2. Create a client #

• Use socket function to create the socket service.

• Use connect function to connect to the socket server.

The following chart shows the communication process between the client and the server:

5.41.3. Socket function #

In Perl, we use socket() function to create a socket in the following syntax format:

socket( SOCKET, DOMAIN, TYPE, PROTOCOL );

Parameter resolution:

• DOMAIN created socket specifies the protocol set. For example:

  • AF_INET represents the IPv4 network protocol

  • AF_INET6 represents IPv6

  • AF_UNIX represents a local socket (using a file)

• TYPE socket types can be classified as SOCK based on whether they are connection oriented or non connection oriented_ STREAM or SOCK_ DGRAM

• PROTOCOL should be (getprotobyname('tcp'))[2] . Specifies the transport protocol actually used.

So socket function is called as follows:

use Socket     # definition  PF_INET and SOCK_STREAM

socket(SOCKET,PF_INET,SOCK_STREAM,(getprotobyname('tcp'))[2]);

5.41.4. Bind () function #

Use bind() assign an address to the socket:

bind( SOCKET, ADDRESS );

SOCKET one descriptor of the socket . ADDRESS , The socket TCP/IP contains three elements:

• Address cluster (TCP/IP, is AF_INET , on your system, it could be 2)

• Port number (for example, 21)

• Network address (e.g. 10.12.12.168)

Use socket() after the socket is created, only the protocol it uses is assigned, and no address is assigned. Before accepting connections from other hosts, you must call the bind() assign an address to the socket.

A simple example is as follows:

use Socket        # Defined PF_INET and SOCK_STREAM

$port = 12345;    # Listening port
$server_ip_address = "10.12.12.168";
bind( SOCKET, pack_sockaddr_in($port, inet_aton($server_ip_address)))
   or die "Unable to bind port! \n";

or die executes after the binding address fails.

By setting up setsockopt() optional SO_REUSEADDR setting port can be reused immediately.

pack_sockaddr_in() function to convert the address to binary format.

5.41.5. Listen () function #

When socket after binding to an address listen() function starts listening for possible connection requests. However, this can only be used when reliable data flow is guaranteed:

listen( SOCKET, QUEUESIZE );

SOCKET : one socket descriptor.

QUEUESIZE is an integer that determines the size of the listening queue,which is entered when a connection request arrives; when a connection request is accept() if accepted, it is removed from the listening queue; when the queue is full, the new connection request returns an error.

Once the connection is accepted, a return of 0 indicates success and an error returns-1.

5.41.6. accept() function #

accept() function to accept the requested socket Connect. If successful, return the compressed network address, otherwise return FALSE :

accept( NEW_SOCKET, SOCKET );

NEW_SOCKET : one socket descriptor.

SOCKET : one socket descriptor.

accept() usually used in infinite loops:

while(1) {
   accept( NEW_SOCKET, SOCKT );
   .......
}

The above example can listen to the client’s request in real time.

5.41.7. connect() function #

connect() system call sets the connection for a socket with parameters such as a file descriptor and a host address.

connect( SOCKET, ADDRESS );

The following creates a connection to the server socket example:

$port = 21;    #  ftp port
$server_ip_address = "10.12.12.168";
connect( SOCKET, pack_sockaddr_in($port, inet_aton($server_ip_address)))
    or die "Unable to bind port! \n";

5.41.8. Example #

#/ Usr/bin/perl - w # File name: server. paste strict; Use Socket# Using Ports
seven thousand eight hundred and ninety
As the default value, my $port=shift | | 7890; My $proto=getprotobyname ('tcp '); My $server="localhost"#
Set local address # to create a socket,
The port can be reused and multiple connection sockets (SOCKET, PF_INET, SOCK_STREAM, $proto) cannot be created
Socket $\ \N "; setsockopt (SOCKET, SOL_SOCKET, SO_REUSEADDR, 1) ordie" cannot be set
SO_ REUSEADDR $\ \N "#
Bind the port and listen for bind (SOCKET, pack_sockaddr_in ($port, inet_aton ($server))) ordie
"Unable to bind port $port! N"; Listen (SOCKET, 5) ordie "listen: $!"; Print "Access Start: $port n"#
Receive request for my $client_ Addr; While ($client_addr=accept (NEW_SOCKET, SOCKET)){#
Send them a message, close
Connectionmy $name=gethostbyaddr ($client_addr, AF_INET); PrintNEW_ SOCKET
"I am information from the server"; Print "Connection
Received from $name n "; closeNEW_SOCKET;}

Open a terminal and execute the following code:

$ perl sever.pl
Access Start：7890

Client client.pl code:

5.41.9. Example #

#/ Usr/bin/perl - w # File name: client. paste strict; Use Socket#
Initialize the address and port my $host=shift | | 'localhost'; My $port=shift | 7890; My $server="localhost"#
Host Address # Create Socket
And connect to socket (SOCKET, PF_INET, SOCK_STREAM, (getprotobyname ('tcp ')) [2]) ordie "Unable to create
Socket $\ \N "; connect (SOCKET, pack_sockaddr in ($port, inet_aton ($server)) ordie" cannot connect:
port $port\ \N "; my $line; while ($line=
<SOCKET>) {print "$line n";} closeSOCKETordie "close: $!";

Open another terminal and execute the following code:

$ perl client.pl
It's information from the server