initial commit

.python-version

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+3.11

README.md

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+mDNS server
+===
+
+Minimalist mDNS server implementation with only core service annoucement and no conflict resolution.
+
+To test our implementation we’re using zeroconf as a trusted client.

main.py

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+import socket
+from dnslib import DNSRecord, DNSHeader, QTYPE, A, SRV, TXT, RR, PTR
+import dns.message
+
+multicast_group = "224.0.0.251"
+multicast_port = 5353
+interface_ip = "0.0.0.0"
+
+def main():
+    sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM, socket.IPPROTO_UDP)
+    sock.setsockopt(socket.IPPROTO_IP, socket.IP_MULTICAST_TTL, 32)
+    # See man socket(7)
+    sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+    #sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEPORT, 1)    
+    
+    sock.bind(("", multicast_port))
+    #   sock.setsockopt(socket.SOL_IP, socket.IP_ADD_MEMBERSHIP, socket.inet_aton(multicast_group) + socket.inet_aton(interface_ip))
+    sock.setsockopt(socket.IPPROTO_IP, socket.IP_MULTICAST_IF, socket.inet_aton(interface_ip))
+    sock.setsockopt(socket.IPPROTO_IP, socket.IP_ADD_MEMBERSHIP, socket.inet_aton(multicast_group) + socket.inet_aton(interface_ip))
+
+    while True:
+        received, sender = sock.recvfrom(1500)
+        print(f'Received packet of {len(received)} bytes from {sender}')
+        try:
+            msg = dns.message.from_wire(received)
+        except dns.exception.FormError:
+            print("Not a valid DNS message")
+            continue
+
+        if msg.opcode() == dns.opcode.QUERY:
+            for question in msg.question:
+                if str(question.name) == '_http._tcp.local.':
+                    print(f"question name {type(msg)}")
+                    unicast_response = question.rdclass == 0x8001
+                    response = DNSRecord(DNSHeader(id = 0, bitmap=0x8400))
+                    ptr = PTR("toto._http._tcp.local")
+                    srv = SRV(target="toto.local", priority=10, port=80, weight=100)
+                    txt = TXT("path=/")
+                    a = A("192.168.1.21")
+                    response.add_answer(RR('_http._tcp.local', QTYPE.PTR, rdata = ptr, ttl=120))
+                    response.add_ar(RR('toto._http._tcp.local', QTYPE.SRV, rdata = srv, ttl=120))
+                    response.add_ar(RR('toto._http._tcp.local', QTYPE.TXT, rdata = txt, ttl=120))
+                    response.add_ar(RR('toto.local', QTYPE.A, rdata = a, ttl=120))
+                    print(str(response))
+                    if unicast_response:
+                        print("Unicast response")
+                        sock.sendto(response.pack(), sender)
+                    else:
+                        print("Multicast response")
+                        sock.sendto(response.pack(), (multicast_group, multicast_port))
+                    print(f'Send response to {sender}')
+
+if __name__ == "__main__":
+    main()

pyproject.toml

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+[project]
+name = "mdns"
+version = "0.1.0"
+description = "Minimalist mdns server"
+readme = "README.md"
+requires-python = ">=3.11"
+dependencies = [
+    "dnslib>=0.9.26",
+    "dnspython>=2.8.0",
+]