ginuerzh
a0427be086
Adds 22 DNS e2e subtests across 8 test methods covering: upstream resolution (A, AAAA, multi-A), TCP mode, bypass rules, host mapper, exchange failure (graceful error recovery), rate limiter wiring, invalid query handling, and DNS over TLS (mode: tls). Includes two authoritative DNS responders (UDP/TCP), a standalone DNS query client, and a TLS DNS query script.
84 lines
2.3 KiB
Python
84 lines
2.3 KiB
Python
"""Simple authoritative DNS responder for TCP mode e2e tests.
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Listens on TCP port 5353 and responds with the same static records
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as dns_responder.py, but over TCP (RFC 5966).
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"""
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import socketserver
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import struct
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import socket
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def decode_name(data, offset):
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labels = []
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while True:
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length = data[offset]
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if length == 0:
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offset += 1
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break
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if length & 0xC0:
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offset += 2
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break
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offset += 1
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labels.append(data[offset:offset + length].decode())
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offset += length
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return '.'.join(labels), offset
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RECORDS = {
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("test.example.com", 1): (1, 300, socket.inet_aton("10.0.0.1")),
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("test2.example.com", 1): (1, 300, socket.inet_aton("10.0.0.2")),
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("example.com", 28): (28, 300, socket.inet_pton(socket.AF_INET6, "::1")),
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}
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class DNSResponder(socketserver.StreamRequestHandler):
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def handle(self):
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# TCP DNS: 2-byte length prefix
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raw = self.rfile.read(2)
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if len(raw) < 2:
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return
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msglen = struct.unpack(">H", raw)[0]
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data = self.rfile.read(msglen)
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if len(data) < 12:
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return
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tid = struct.unpack(">H", data[:2])[0]
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qdcount = struct.unpack(">H", data[4:6])[0]
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if qdcount == 0:
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return
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qname, pos = decode_name(data, 12)
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qtype = struct.unpack(">H", data[pos:pos + 2])[0]
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qclass = struct.unpack(">H", data[pos + 2:pos + 4])[0]
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key = (qname, qtype)
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if key in RECORDS:
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rcode = 0
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ancount = 1
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rtype, ttl, rdata = RECORDS[key]
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else:
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rcode = 3 # NXDOMAIN
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ancount = 0
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rtype, ttl, rdata = 0, 0, b""
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flags = 0x8000 | 0x0400 | rcode
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header = struct.pack(">HHHHHH", tid, flags, qdcount, ancount, 0, 0)
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question = data[12:pos + 4]
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answer = b""
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if ancount:
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answer = (
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struct.pack(">HH", 0xC00C, rtype)
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+ struct.pack(">HI", qclass, ttl)
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+ struct.pack(">H", len(rdata)) + rdata
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)
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dnsmsg = header + question + answer
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self.wfile.write(struct.pack(">H", len(dnsmsg)) + dnsmsg)
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if __name__ == "__main__":
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with socketserver.TCPServer(("0.0.0.0", 5353), DNSResponder) as srv:
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srv.serve_forever()
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