zeroconnect 1.0.1

Use zeroconf to automatically connect devices via TCP on a LAN

zeroconnect

Use zeroconf to automatically connect devices via TCP on a LAN. I can hardly believe this doesn't exist already, but after searching for an hour, in despair I resign myself to write my own, and patch the glaring hole in existence.

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Table of Contents

• Installation
• Usage
• License
• Tips
• Bonus!

Installation

pip install zeroconnect

Usage

One or more servers, and one or more clients, run connected to the same LAN. (Wifi or ethernet.)

Most basic

Service:

from zeroconnect import ZeroConnect

def rxMessageConnection(messageSock, nodeId, serviceId):
    print(f"got message connection from {nodeId}")
    data = messageSock.recvMsg()
    print(data)
    messageSock.sendMsg(b"Hello from server")

ZeroConnect().advertise(rxMessageConnection, "YOUR_SERVICE_ID_HERE")

Client:

from zeroconnect import ZeroConnect
messageSock = ZeroConnect().connectToFirst("YOUR_SERVICE_ID_HERE")
messageSock.sendMsg(b"Hello from client")
data = messageSock.recvMsg()
print(data)

Less basic

Service:

from zeroconnect import ZeroConnect

SERVICE_ID = "YOUR_SERVICE_ID_HERE"
zc = ZeroConnect("NODE_ID")

def rxMessageConnection(messageSock, nodeId, serviceId):
    print(f"got message connection from {nodeId}")
    # If you also want to spontaneously send messages, pass the socket to e.g. another thread.
    while True:
        data = messageSock.recvMsg()
        print(data)
        if data == b'enable jimjabber':
            print(f"ENABLE JIMJABBER")
        elif data == b'save msg:':
            toSave = messageSock.recvMsg()
            print(f"SAVE MESSAGE {toSave}")
        elif data == b'marco':
            messageSock.sendMsg(b'polo')
            print(f"PING PONGED")
        elif data == None:
            print(f"Connection closed from {nodeId}")
            messageSock.close()
            return
        else:
            print(f"Unhandled message: {data}")
        # Use messageSock.sock for e.g. sock.getsockname()
        # I recommend messageSock.close() after you're done with it - but it'll get closed on zc.close(), at least

zc.advertise(rxMessageConnection, SERVICE_ID) # Implicit mode=SocketMode.Messages

try:
    input("Press enter to exit...\n\n")
finally:
    zc.close()

Client:

from zeroconnect import ZeroConnect, SocketMode

SERVICE_ID = "YOUR_SERVICE_ID_HERE"
zc = ZeroConnect("NODE_ID") # Technically the nodeId is optional; it'll assign you a random UUID

ads = zc.scan(SERVICE_ID, time=5)
# OR: ads = zc.scan(SERVICE_ID, NODE_ID)
# An `Ad` contains a `serviceId` and `nodeId` etc.; see `Ad` for details
messageSock = zc.connect(ads[0], mode=SocketMode.Messages) # Send and receive messages; the default mode
# OR: messageSock = zc.connectToFirst(SERVICE_ID)
# OR: messageSock = zc.connectToFirst(nodeId=NODE_ID)
# OR: messageSock = zc.connectToFirst(SERVICE_ID, NODE_ID, timeout=10)

messageSock.sendMsg(b"enable jimjabber")
messageSock.sendMsg(b"save msg:")
messageSock.sendMsg(b"i love you")
messageSock.sendMsg(b"marco")
print(f"rx: {messageSock.recvMsg()}")

# ...

zc.close()

You can also get raw sockets rather than MessageSockets, if you prefer:

Server:

from zeroconnect import ZeroConnect, SocketMode

SERVICE_ID = "YOUR_SERVICE_ID_HERE"
zc = ZeroConnect("NODE_ID")

def rxRawConnection(sock, nodeId, serviceId):
    print(f"got raw connection from {nodeId}")
    data = sock.recv(1024)
    print(data)
    sock.sendall(b"Hello from server\n")
    # sock is a plain socket; use accordingly

zc.advertise(rxRawConnection, SERVICE_ID, mode=SocketMode.Raw)

try:
    input("Press enter to exit...\n\n")
finally:
    zc.close()

Client:

from zeroconnect import ZeroConnect, SocketMode

SERVICE_ID = "YOUR_SERVICE_ID_HERE"
zc = ZeroConnect("NODE_ID") # Technically the nodeId is optional; it'll assign you a random UUID

ads = zc.scan(SERVICE_ID, time=5)
# OR: ads = zc.scan(SERVICE_ID, NODE_ID)
# An `Ad` contains a `serviceId` and `nodeId` etc.; see `Ad` for details
sock = zc.connect(ads[0], mode=SocketMode.Raw) # Get the raw streams
# OR: sock = zc.connectToFirst(SERVICE_ID, mode=SocketMode.Raw)
# OR: sock = zc.connectToFirst(nodeId=NODE_ID, mode=SocketMode.Raw)
# OR: sock = zc.connectToFirst(SERVICE_ID, NODE_ID, mode=SocketMode.Raw, timeout=10)

sock.sendall(b"Hello from client\n")
data = sock.recv(1024)
print(f"rx: {data}")

# ...

zc.close()

There's a few other functions you might find useful. Look at the source code. Here; I'll paste the declaration of all the public ZeroConnect methods here.

    def __init__(self, localId=None):
    def advertise(self, callback, serviceId, port=0, host="0.0.0.0", mode=SocketMode.Messages):
    def scan(self, serviceId=None, nodeId=None, time=30):
    def scanGen(self, serviceId=None, nodeId=None, time=30):
    def connectToFirst(self, serviceId=None, nodeId=None, localServiceId="", mode=SocketMode.Messages, timeout=30):
    def connect(self, ad, localServiceId="", mode=SocketMode.Messages):
    def broadcast(self, message, serviceId=None, nodeId=None):
    def getConnections(self):
    def close(self):

Tips

Be careful not to have two nodes recv from each other at the same time, or they'll deadlock. However, you CAN have them send at the same time (at least according to my tests).

ZeroConnect is intended to be manipulated via its methods, but it probably won't immediately explode if you read the data in the fields.

Note that some computers/networks block zeroconf, or external connection attempts, etc.

Calling broadcast will automatically clean up dead connections.

If you close your socket immediately after sending a message, the data may not finish sending. Not my fault; blame socket.

broadcast uses MessageSockets, so if you're using a raw socket, be aware the message will be prefixed with a header, currently an 8 byte unsigned long representing the length of the subsequent message. See MessageSocket.

See logging.py to see logging settings, or do like so:

from zeroconnect.logging import *
setLogLevel(-1) # 4+ for everything current, -1 for nothing except uncaught exceptions
# It also contains some presets; ERROR/WARN/INFO/VERBOSE/DEBUG atm.
# Also, you can move all the logging to stderr with `setLogType(2)`.

Bonus!

Also includes zcat, like ncat/nc/netcat. Use as follows:

RX:

python -m zeroconnect.zcat -l SERVICE_ID [NODE_ID] > FILE

TX:

cat FILE | python -m zeroconnect.zcat SERVICE_ID [NODE_ID]

License

zeroconnect is distributed under the terms of the MIT license.

TODO

ssl lower timeouts? connect to all, forever? connection callback maybe some automated tests? .advertiseSingle to get one connection? for quick stuff?