feat: add comprehensive DNS handler e2e tests

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.
2026-06-27 00:21:37 +08:00
parent 590c6f48bd
commit a0427be086
13 changed files with 989 additions and 0 deletions
@@ -0,0 +1,88 @@
+"""Simple authoritative DNS responder for e2e tests.
+
+Listens on UDP port 5353 and responds with static records:
+
+  test.example.com.   IN A     10.0.0.1
+  test2.example.com.  IN A     10.0.0.2
+  example.com.        IN AAAA  ::1
+
+All other queries receive NXDOMAIN.
+"""
+import socketserver
+import struct
+import socket
+
+
+def decode_name(data, offset):
+    labels = []
+    while True:
+        length = data[offset]
+        if length == 0:
+            offset += 1
+            break
+        if length & 0xC0:
+            offset += 2
+            break
+        offset += 1
+        labels.append(data[offset:offset + length].decode())
+        offset += length
+    return '.'.join(labels), offset
+
+
+def encode_name(name):
+    parts = name.rstrip(".").split(".")
+    return b"".join(bytes([len(p)]) + p.encode() for p in parts) + b"\x00"
+
+
+RECORDS = {
+    ("test.example.com", 1): (1, 300, socket.inet_aton("10.0.0.1")),
+    ("test2.example.com", 1): (1, 300, socket.inet_aton("10.0.0.2")),
+    ("example.com", 28): (28, 300, socket.inet_pton(socket.AF_INET6, "::1")),
+}
+
+
+class DNSResponder(socketserver.DatagramRequestHandler):
+    def handle(self):
+        data = self.rfile.read(512)
+        if len(data) < 12:
+            return
+
+        tid = struct.unpack(">H", data[:2])[0]
+        qdcount = struct.unpack(">H", data[4:6])[0]
+
+        if qdcount == 0:
+            return
+
+        qname, pos = decode_name(data, 12)
+        qtype = struct.unpack(">H", data[pos:pos + 2])[0]
+        qclass = struct.unpack(">H", data[pos + 2:pos + 4])[0]
+
+        key = (qname, qtype)
+        if key in RECORDS:
+            rcode = 0
+            ancount = 1
+            rtype, ttl, rdata = RECORDS[key]
+        else:
+            rcode = 3  # NXDOMAIN
+            ancount = 0
+            rtype, ttl, rdata = 0, 0, b""
+
+        flags = 0x8000 | 0x0400 | rcode  # QR=1, AA=1, rcode
+        header = struct.pack(">HHHHHH", tid, flags, qdcount, ancount, 0, 0)
+
+        question = data[12:pos + 4]
+
+        answer = b""
+        if ancount:
+            answer = (
+                struct.pack(">HH", 0xC00C, rtype)  # NAME pointer + TYPE
+                + struct.pack(">HI", qclass, ttl)   # CLASS + TTL
+                + struct.pack(">H", len(rdata)) + rdata  # RDLENGTH + RDATA
+            )
+
+        self.wfile.write(header + question + answer)
+
+
+if __name__ == "__main__":
+    with socketserver.UDPServer(("0.0.0.0", 5353), DNSResponder) as srv:
+        srv.serve_forever()