Find roscores running in your network

find_roscores.py

#/usr/bin/env python
import socket
import time
from multiprocessing import Process, Queue

def check_server(address, queue, port=11311):
    # Create a TCP socket
    s = socket.socket()
    try:
        s.connect((address, port))
        # print("Port open at IP %s (on port %s)" % (address, port))
        queue.put((True, address, port))
    except socket.error as e:
        # print("Connection to %s on port %s failed: %s" % (address, port, e))
        queue.put((False, address, port))


def get_own_ip():
    return ((([ip for ip in socket.gethostbyname_ex(socket.gethostname())[2] if not ip.startswith("127.")] or [[(s.connect(("8.8.8.8", 53)), s.getsockname()[0], s.close()) for s in [socket.socket(socket.AF_INET, socket.SOCK_DGRAM)]][0][1]]) + ["no IP found"])[0])


def scan_for_roscore(own_ip=None, timeout=3.0):
    """
    Scan for port 11311 open on a subnet.
    """
    if own_ip is None:
        own_ip = get_own_ip()
    if own_ip:
        ip_split = own_ip.split('.')
        subnet = ip_split[:-1]
        subnetstr = '.'.join(subnet)
        processes = []
        q = Queue()
        for i in range(1, 255):
            ip = subnetstr + '.' + str(i)
            p = Process(target=check_server, args=[ip, q])
            processes.append(p)
            p.start()
        # give a bit of time...
        time.sleep(timeout)

        found_ips = []
        for idx, p in enumerate(processes):
            if p.exitcode is None:
                # print("Terminating: " + str(idx))
                p.terminate()
            else:
                open_ip, address, port = q.get()
                if open_ip:
                    found_ips.append(address)

        for idx, p in enumerate(processes):
            # print("joining " + str(idx))
            p.join()

        print("Found ips: " + str(found_ips))
        return found_ips

    else:
        print("Could not get our own IP, can't scan our network.")
        return []
      
if __name__ == '__main__':
    print(scan_for_roscore())