Network

This document introduces a set of functions about TCP and UDP in Melang.

mln_tcpConnect

create a TCP connection to server.

@mln_tcpConnect(host, service, timeout);

Input:

• host - a string value. It can be an IP or domain name.
• service - a string value. It can be a port number or protocol name, like: http, 80.
• timeout - a millisecond timer. It’s an optional argument. It must be an positive integer or zero (timeout immediately). Omit means never timeout.

Return value:

• a TCP socket file descriptor return on success
• nil on timed out
• otherwise false returned

mln_tcpListen

Set up a TCP listen socket.

@mln_tcpListen(host, service); 

Input:

• host - a string value. It can be an IP or domain name.
• service - a string value. It can be a port number or protocol name, like: http, 80.

Return value:

• a TCP socket file descriptor return on success, otherwise false returned.

mln_tcpAccept

Accept a TCP connection.

@mln_tcpAccept(listenfd, timeout); 

Input:

• listened - an integer value generated by mln_tcpListen.
• timeout - a millisecond timer. It’s an optional argument. It must be an positive integer or zero (timeout immediately). Omit means never timeout.

Return value:

• a TCP socket file descriptor return on success.
• If timeout >= 0 and no TCP arrived, nil will be returned.
• Otherwise, false returned.

mln_tcpSend

Send ‘data’ via TCP.

@mln_tcpSend(sockfd, data); 

Input:

• socked - a socket file descriptor which is an integer.
• data - a string value.

Return value:

• true returned on success, otherwise false returned.

mln_tcpRecv

Receive data from TCP.

@mln_tcpRecv(sockfd, timeout);  

Input:

• sockfd - a socket file descriptor which is an integer.
• timeout - a millisecond timer. It’s an optional argument. It must be an positive integer or zero (timeout immediately). Omit means never timeout.

Return value:

• Received data will be returned on success.
• If timeout >= 0 and no data arrived, nil will be returned.
• If TCP closed, true will be returned.
• Otherwise false returned.

mln_tcpClose

Close a TCP connection.

@mln_tcpClose(sockfd);

Input:

• sockfd - a socket file descriptor which is an integer.

Return value:

• Always nil.

mln_tcpShutdown

Shutdown TCP connection.

@mln_tcpShutdown(sockfd, mode); 

Input:

• sockfd - a socket file descriptor which is an integer.
• mode - a string and only has two values: send and recv.

Return value:

• Always nil.

mln_udpCreate

Create an UDP socket.

@mln_udpCreate(host, service);

Input:

• host - a string value. It can be an IP or domain name.
• service - a string value. It can be a port number or protocol name, like: http, 80.

Return value:

• a TCP socket file descriptor return on success, otherwise false returned.

mln_udpClose

Close an UDP socket.

@mln_udpClose(fd);

Input:

• fd - an UDP socket file descriptor generated by mln_udpCreate.

Return value:

• Always nil.

mln_udpSend

Send data via UDP.

@mln_udpSend(fd, data, host, service); 

Input:

• fd. - an UDP socket file descriptor generated by mln_udpCreate.
• data - a string value.
• host - a string value. It can be an IP or domain name. This is the destination host.
• service - a string value. It can be a port number or protocol name, like: http, 80. This is the destination service name.

Return value:

• true will be returned on success, otherwise false returned.

mln_udpRecv

Receive data from UDP.

@mln_udpRecv(fd, bufsize, &ip, &port, timeout);

Input:

• fd - an UDP socket file descriptor generated by mln_udpCreate.
• bufsize - an integer indicates the UDP receiving buffer size.
• ip - sender’s IP. This is an output argument.
• port - sender’s port. This is an output argument.
• timeout - a millisecond timer. It’s an optional argument. It must be an positive integer or zero (timeout immediately). Omit means never timeout.

Return value:

• Received data will be returned on success.
• If timeout >= 0 and no data arrived, nil will be returned.
• Otherwise false returned.

Example

//client.mln
fd = @mln_tcpConnect('127.0.0.1', '1234');
@mln_print(fd);
@mln_tcpSend(fd, 'Hello');
@mln_print(@mln_tcpRecv(fd));
@mln_tcpClose(fd);

//server.mln
listenfd = @mln_tcpListen('127.0.0.1', '1234');
connfd = @mln_tcpAccept(listenfd);
@mln_print(@mln_tcpRecv(connfd));
@mln_tcpSend(connfd, 'Hi');
@mln_tcpClose(connfd);

$ melang server.mln client.mln

The output is:

10
Hello
Hi