examples/network: Add UDP multicast client and server examples.

Signed-off-by: IhorNehrutsa <Ihor.Nehrutsa@gmail.com>

examples/network/udp_multicast_client.py

@@ -0,0 +1,63 @@
+# udp_multicast_client.py::
+
+import network, socket, errno, struct, time
+
+print("connect to AP")
+
+SSID = 'SSID'
+PASSWORD = 'PASSWORD'
+
+wlan = network.WLAN(network.STA_IF)
+wlan.ifconfig(('172.16.55.55', '255.255.255.0', '172.16.55.1', '172.16.55.1'))  # class B network
+wlan.active(True)
+wlan.connect(SSID, PASSWORD)
+while not wlan.isconnected():
+    pass
+
+print("udp_multicast_client.py")
+print("client send GET and receive ACK from the server")
+
+def inet_aton(str_addr):
+    return bytes(map(int, str_addr.split(".")))
+
+#TIMEOUT = None  # block
+#TIMEOUT = 5  # s
+TIMEOUT = 0  # non blocking
+
+MULTICAST_IP = '224.0.0.111'
+PORT = 5555
+sockaddr = (MULTICAST_IP, PORT)
+
+wlan = network.WLAN(network.STA_IF)
+client_ip = wlan.ifconfig()[0]
+
+skt = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)  # UDP
+skt.settimeout(None)
+skt.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+skt.setsockopt(socket.IPPROTO_IP, socket.IP_ADD_MEMBERSHIP, struct.pack(">4s4s", inet_aton(MULTICAST_IP), inet_aton(client_ip)))  # join to the multicast address
+skt.bind(sockaddr)  # not skt.connect(sockaddr)
+skt.settimeout(TIMEOUT)
+
+t = 0
+while True:
+    try:
+        if time.time() - t >= 3:
+            t = time.time()
+
+            mac = wlan.config('mac')
+            str_to_send = f"client_ip:{client_ip}\t mac:{'-'.join(map('{:02x}'.format, mac))}"
+            skt.sendto(str_to_send, sockaddr)
+            print(f'GET to   {sockaddr}\t sent     "{str_to_send}"')
+
+        received, addr = skt.recvfrom(1024)
+        if received:
+            print(f'ACK from {addr}\t received "{received.decode()}"')
+    except OSError as e:
+        if e.args[0] in (errno.EAGAIN, errno.ETIMEDOUT):
+            pass
+        else:
+            try:
+                skt.close()
+            except:
+                pass
+            raise(e)

examples/network/udp_multicast_server.py

@@ -0,0 +1,59 @@
+# udp_multicast_server.py::
+
+import network, socket, errno, struct, time
+
+print("connect to AP")
+
+SSID = 'SSID'
+PASSWORD = 'PASSWORD'
+
+wlan = network.WLAN(network.STA_IF)
+wlan.ifconfig(('192.168.44.44', '255.255.255.0', '192.168.44.1', '192.168.44.1'))  # class C network
+wlan.active(True)
+wlan.connect(SSID, PASSWORD)
+while not wlan.isconnected():
+    pass
+
+print("udp_multicast_server.py")
+print("server receive GET and send ACK to the client")
+
+def inet_aton(str_addr):
+    return bytes(map(int, str_addr.split(".")))
+
+#TIMEOUT = None  # block
+#TIMEOUT = 5  # s
+TIMEOUT = 0  # non blocking
+
+MULTICAST_IP = '224.0.0.111'
+PORT = 5555
+sockaddr = (MULTICAST_IP, PORT)
+
+wlan = network.WLAN(network.STA_IF)
+server_ip = wlan.ifconfig()[0]
+
+skt = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)  # UDP
+skt.settimeout(None)
+skt.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+skt.setsockopt(socket.IPPROTO_IP, socket.IP_ADD_MEMBERSHIP, struct.pack(">4s4s", inet_aton(MULTICAST_IP), inet_aton(server_ip)))  # join to the multicast address
+skt.bind(sockaddr)
+skt.settimeout(TIMEOUT)
+
+while True:
+    try:
+        received, addr = skt.recvfrom(1024)
+        if received:
+            print(f'GET from {addr}\t received "{received.decode()}"')
+
+            mac = wlan.config('mac')
+            str_to_send = f"server_ip:{server_ip}\t mac:{'-'.join(map('{:02x}'.format, mac))}"
+            skt.sendto(str_to_send, sockaddr)
+            print(f'ACK to   {sockaddr}\t sent     "{str_to_send}"')
+    except OSError as e:
+        if e.args[0] in (errno.EAGAIN, errno.ETIMEDOUT):
+            pass
+        else:
+            try:
+                skt.close()
+            except:
+                pass
+            raise(e)