feat(mdns): one-shot browse tool; iDRAC SNMP live both DRACs; Govee creds [#619][#625]

💘 Generated with Crush Assisted-by: Crush:glm-5.2
2026-09-02 12:44:44 -05:00
parent 2c12d7b39e
commit a2ff60908e
2 changed files with 115 additions and 3 deletions
@@ -0,0 +1,101 @@
+#!/usr/bin/env python3
+"""mdns-browse: one-shot multicast mDNS enumeration from this vantage.
+
+Sends PTR queries for the DNS-SD service-enumeration name plus common
+service types, listens briefly, prints every answer record. Stdlib only.
+Diagnostic tool for #619 (WiFi-side multicast reachability)."""
+
+import socket
+import struct
+import sys
+import time
+
+MDNS_GROUP = "224.0.0.251"
+MDNS_PORT = 5353
+LISTEN_SECONDS = float(sys.argv[1]) if len(sys.argv) > 1 else 6.0
+TYPES = {
+    1: "A", 28: "AAAA", 12: "PTR", 16: "TXT", 33: "SRV", 47: "NONE",
+}
+QUERIES = [
+    "_services._dns-sd._udp.local",
+    "_hap._tcp.local",
+    "_airplay._tcp.local",
+    "_googlecast._tcp.local",
+]
+
+
+def encode_name(name):
+    out = b""
+    for part in name.split("."):
+        out += bytes([len(part)]) + part.encode("latin1")
+    return out + b"\x00"
+
+
+def read_name(data, off):
+    parts = []
+    seen = set()
+    while True:
+        if off in seen or len(seen) > 64:
+            return ".".join(parts), off
+        seen.add(off)
+        length = data[off]
+        if length == 0:
+            off += 1
+            break
+        if length & 0xC0:
+            ptr = struct.unpack(">H", data[off:off + 2])[0] & 0x3FFF
+            parts.append(read_name(data, ptr)[0])
+            off += 2
+            break
+        parts.append(data[off + 1:off + 1 + length].decode("latin1"))
+        off += 1 + length
+    return ".".join(parts), off
+
+
+def build_query(names):
+    packet = struct.pack(">HHHHHH", 0, 0, len(names), 0, 0, 0)
+    for name in names:
+        packet += encode_name(name) + struct.pack(">HH", 12, 1)
+    return packet
+
+
+def main():
+    sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+    sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+    sock.bind(("", MDNS_PORT))
+    mreq = socket.inet_aton(MDNS_GROUP) + socket.inet_aton("0.0.0.0")
+    sock.setsockopt(socket.IPPROTO_IP, socket.IP_ADD_MEMBERSHIP, mreq)
+    sock.settimeout(0.5)
+    sock.sendto(build_query(QUERIES), (MDNS_GROUP, MDNS_PORT))
+    deadline = time.time() + LISTEN_SECONDS
+    found = set()
+    while time.time() < deadline:
+        try:
+            data, addr = sock.recvfrom(16384)
+        except socket.timeout:
+            continue
+        an = struct.unpack(">H", data[6:8])[0]
+        off = 12
+        qd = struct.unpack(">H", data[4:6])[0]
+        try:
+            for _ in range(qd):
+                _, off = read_name(data, off)
+                off += 4
+            for _ in range(an):
+                name, name_end = read_name(data, off)
+                rtype, _rclass, ttl, rlen = struct.unpack(
+                    ">HHIH", data[name_end:name_end + 10])
+                detail = ""
+                if rtype == 12:
+                    detail = " -> " + read_name(data, name_end + 10)[0]
+                found.add((TYPES.get(rtype, rtype), name, detail, addr[0]))
+                off = name_end + 10 + rlen
+        except (IndexError, struct.error):
+            continue
+    for rtype, name, detail, src in sorted(found):
+        print(f"{src:15} {rtype:5} {name}{detail}")
+    print(f"-- {len(found)} records from {LISTEN_SECONDS}s listen --")
+
+
+if __name__ == "__main__":
+    main()