Sockets: Difference between revisions

Tested using <code>nc -l 256</code>, on both macOS Sierra and Windows 7, compiled using Free Pascal.

<lang pascal>Program Sockets_Example;

Uses

{ Free Pascal RTL sockets unit }

sockets;

Var

TCP_Sock: integer;

Remote_Addr: TSockAddr;

Message: string;

Begin

{ Fill the record (struct) with the server's address information }

With Remote_Addr do

begin

Sin_family := AF_INET;

Sin_addr := StrToNetAddr('127.0.0.1');

Sin_port := HtoNs(256); { Converts short integer to network byte order }

end;

{ Returns an IPv4 TCP socket descriptor }

TCP_Sock := fpSocket(AF_INET, SOCK_STREAM, IPPROTO_IP);

{ fpSocket returns -1 on failure }

If TCP_Sock = -1 then

begin

WriteLn('Failed to create new socket descriptor');

Halt(1);

end;

{ Attempt to connect to the address supplied above }

If fpConnect(TCP_Sock, @Remote_Addr, SizeOf(Remote_Addr)) = -1 then

begin

{ Specifc error codes can be retrieved by calling the SocketError function }

WriteLn('Failed to contact server');

Halt(1);

end;

{ Finally, send the message to the server and disconnect }

Message := 'Hello socket world';

fpSend(TCP_Sock, @Message, SizeOf(Message), 0);

CloseSocket(TCP_Sock);

End.

</lang>