How to create a dummy "pipe" pseudo-serial device on Linux?

Question

I need to write a program (C++) that uses a serial port to communicate with another device. The other device isn't even built yet so I need a software emulator For various reasons there is no point going into here, the software emulator needs to run on a different machine. I would like to send the data via UDP from the software emulator to the machine my program is running on and have it received by another serial interface type program that in some way acts as a serial port (serial tty device).

I also want to test my program in an automated fashion in a VM. Ideally my test program would also use UDP and would use the same UDP-serial interface program to forward the data back and forwards between my test program and the program under test.

Time is very tight. I don't really have time to learn to write and install kernel level device drivers.

I would be very grateful for any pointers as to how I can create some sort of "pipe" or "loopback" pseudo-serial device.

I am working on Linux.

Answer 1

Credit to meuh for his tip-off.

socat UDP:127.0.0.1:5001,bind=127.0.0.1:5000 \
      PTY,link=/dev/ttyS0,raw,echo=0,waitslave

This listens on UDP port 5000 on the loopback network interface. All data received is sent to the virtual serial device at /dev/ttyS0. All data received on the virtual serial device is sent to UDP address 127.0.0.1:5001.

The IP address can be remote.

The command must be run as root, as must the process connecting to the serial port. To avoid this use a different file path, e.g. /tmp/ttyS99.

Apparently the file path specified must not already exist. However my PC has /dev/ttyS0 all the way to /dev/ttyS31 despite not having any serial ports, and using /dev/ttyS0 works fine. I suppose if I actually had a real serial port this wouldn't work.