Plan 9 networking

Using the /net filesystem

You can make network connections just by interacting with files in /net.

Connecting via TCP

First you could create a new socket by reading the contents of /net/tcp/clone, then one would write to the socket in /net/tcp/$socketno/ctl, to connect to some host, and then read/write to /net/tcp/$socketno/data.

Apparently, one can’t close the /net/tcp/clone file after reading from it or the connection will be closed, and this code keeps it open by piping it to a file descriptor and not closing it until we’re done.

I don’t know what the file descriptor “5” is.

<[5] /net/tcp/clone {   # Pipe the /net/tcp/clone file to fd 5.
            # Don't close it until this block is closed?
    netdir = '/net/tcp/' ^ `{cat /fd/5}

    # Connect to some host 9.9.9.9 on port 19
    echo connect 9.9.9.9!19 > $netdir/ctl || echo cant connect
    cat $netdir/data
}

This task is eased by the aux/trampoline tool trampoline(8), and by the dial(2) C function.

aux/listen1

aux/listen

/bin/service/

Comments

                                                                          
                                   ,,           ,,          ,,            
                            mm     db         `7MM        `7MM            
                            MM                  MM          MM            
 .P"Ybmmm ,pW"Wq.   ,6"Yb.mmMMmm `7MM  ,pP"Ybd  MMpMMMb.    MM `7M'   `MF'
:MI  I8  6W'   `Wb 8)   MM  MM     MM  8I   `"  MM    MM    MM   VA   ,V  
 WmmmP"  8M     M8  ,pm9MM  MM     MM  `YMMMa.  MM    MM    MM    VA ,V   
8M       YA.   ,A9 8M   MM  MM     MM  L.   I8  MM    MM    MM     VVV    
 YMMMMMb  `Ybmd9'  `Moo9^Yo.`Mbmo.JMML.M9mmmP'.JMML  JMML..JMML.   ,V     
6'     dP                                                         ,V      
Ybmmmd'                                                        OOb"