CircuitPython and desktop Python (CPython) multicast sender & receiver

circuitpython-udp-multicast-receiver.py

import wifi
import socketpool
import ipaddress
import time, os

ssid = os.getenv("CIRCUITPY_WIFI_SSID")
password = os.getenv("CIRCUITPY_WIFI_PASSWORD")

HOST = "224.0.0.1"  # multicast LAN address
PORT = 5000
TIMEOUT = None
MAXBUF = 256

print("Connecting to Wifi", ssid)
wifi.radio.connect(ssid, password)
pool = socketpool.SocketPool(wifi.radio)

print("Self IP", wifi.radio.ipv4_address)
server_ipv4 = ipaddress.ip_address(pool.getaddrinfo(HOST, PORT)[0][4][0])
print("Server", server_ipv4, "port", PORT)

s = pool.socket(pool.AF_INET, pool.SOCK_DGRAM)

# currently undocumented: same as sock.setsockopt(socket.IPPROTO_IP, socket.IP_MULTICAST_TTL, ttl)
IPPROTO_IP = 0
IP_MULTICAST_TTL = 5
ttl = 2
s.setsockopt( IPPROTO_IP, IP_MULTICAST_TTL, ttl)

s.settimeout(TIMEOUT)

s.bind((HOST, PORT))

buf = bytearray(MAXBUF)
while True:
    size, addr = s.recvfrom_into(buf)
    print("Received", buf[:size], size, "bytes from", addr)

    #size = s.sendto(buf[:size], addr)
    #print("Sent", buf[:size], size, "bytes to", addr)

udp-multicast-receiver.py

# invoke like: python3 ./udp-multicast-receiver 224.0.0.1 5000
# can have multi receivers on different computers on the same LAN and they all receive the messages
import time, socket, sys

if len(sys.argv) < 2 or len(sys.argv) > 3:
    print("udp-multicast-receiver.py <host> <port>")
    exit(0)

udp_host = sys.argv[1]
udp_port = int(sys.argv[2])

sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) # UDP

ttl = 2
sock.setsockopt(socket.IPPROTO_IP, socket.IP_MULTICAST_TTL, ttl)

sock.bind((udp_host,udp_port))

print("waiting for packets on",udp_host,udp_port)
while True:
     data, addr = sock.recvfrom(1024) # buffer size is 1024 bytes
     print("received message: %s" % data)

udp-multicast-sender.py

# invoke like: python3 ./udp-multicast-sender 224.0.0.1 5000 "hey buddy"
# can have multiple senders on different computers on the same LAN all sending to the multiple receivers
import time, socket, sys

if len(sys.argv) < 3 or len(sys.argv) > 4:
    print("udp-multicast-sender.py <host> <port> [msg]")
    exit(0)

udp_host = sys.argv[1]
udp_port = int(sys.argv[2])
message = "hi there!"

if sys.argv == 4:
    message = argv[3]

sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) # UDP

ttl = 2
sock.setsockopt(socket.IPPROTO_IP, socket.IP_MULTICAST_TTL, ttl)

num = 0
while True:
    udp_message = bytes( f"{message} {num}", 'utf-8')
    num += 1
    print(time.monotonic(), f"sending to {udp_host}:{udp_port} message:", udp_message)
    sock.sendto(udp_message, (udp_host,udp_port) )
    time.sleep(1)