feat: complete service exploration

main.py

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+import argparse
+import threading
+from src.communication import ServiceExplorationModule
+from src.parser import get_args
+
+if __name__ == '__main__':
+    args = get_args()
+
+    socket_type = args.type
+    host, port = args.host, args.port
+
+    # start Service Exploration Module
+    # let all client can know which IP address has our service so that it can link to.
+    service_explore = ServiceExplorationModule(host, port+1)
+    explore_service_thread = threading.Thread(target=service_explore.listen)
+    explore_service_thread.start()
+
+    if socket_type == 'client':
+        hosts = service_explore.explore()
+        print(hosts)
+

src/communication.py

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+import socket
+
+class ServiceExplorationModule():
+    def __init__(self, host, port):
+        # UDP server
+        self.sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+        self.sock.setsockopt(socket.SOL_SOCKET, socket.SO_BROADCAST, 1)
+        self.host = host
+        self.port = port
+        self.IP = socket.gethostbyname(socket.gethostname())
+        self.is_available = True
+
+    def listen(self):
+        self.sock.bind((self.host, self.port))
+        print(f"Exploration Server(UDP) listening on {self.host}:{self.port}...")
+
+        while True:
+            data, addr = self.sock.recvfrom(1024)
+
+            if self.is_available:
+                if data.decode() == '[EXPLORE]':
+                    print(f"Receive exploration broadcast from {addr}")
+                    self.sock.sendto(self.IP.encode(), addr)
+
+    def explore(self):
+        available_host = []
+
+        client_sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+        client_sock.setsockopt(socket.SOL_SOCKET, socket.SO_BROADCAST, 1)
+
+        client_sock.settimeout(3)
+        client_sock.sendto('[EXPLORE]'.encode(), ('255.255.255.255', self.port))
+
+        while True:
+            try:
+                data, addr = client_sock.recvfrom(1024)
+                if addr[0] != self.IP:
+                    available_host.append(addr)
+            except:
+                # if socket timeout
+                break
+        return available_host

src/parser.py

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+import argparse
+
+def get_args():
+    parser = argparse.ArgumentParser()
+    parser.add_argument('type', type=str, help="'client' or 'server'", default='server')
+    parser.add_argument('--host', type=str, help="server's IPv4 address", default='0.0.0.0')
+    parser.add_argument('--port', type=int, help="server's listening port", default=8888)
+
+    args = parser.parse_args()
+    return args