136 lines
4.3 KiB
Python
Executable File
136 lines
4.3 KiB
Python
Executable File
#!/usr/bin/env python3
|
||
"""
|
||
Send DNS NOTIFY messages (RFC 1996) to Hurricane Electric's secondary
|
||
nameservers, telling them to re-poll our zones immediately rather than
|
||
waiting for the next SOA-refresh cycle (up to 1 hour).
|
||
|
||
This replicates what CoreDNS's `transfer { to <IP> }` directive would do
|
||
natively, but as an external script because that directive silently
|
||
breaks server-block startup on CoreDNS 1.11.3 + 1.12.2 in our config.
|
||
|
||
Called automatically from `make prep`. No dependencies beyond Python 3
|
||
stdlib — we craft the 12-byte DNS header + question section by hand.
|
||
|
||
NOTIFY semantics:
|
||
- QR=0 (query), Opcode=4 (NOTIFY), AA=1 (we're authoritative)
|
||
- QDCOUNT=1, question = <zone> SOA IN
|
||
- Slave responds with NOERROR + similar header, then issues AXFR/SOA
|
||
queries to see if the zone has actually changed.
|
||
"""
|
||
from __future__ import annotations
|
||
|
||
import os
|
||
import random
|
||
import socket
|
||
import struct
|
||
import sys
|
||
from pathlib import Path
|
||
|
||
HE_NAMESERVERS = [
|
||
"216.218.130.2", # ns1.he.net — the NOTIFY-accepting endpoint
|
||
# (HE's slave cluster replicates internally; one
|
||
# NOTIFY here wakes the whole pool)
|
||
]
|
||
|
||
DNS_PORT = 53
|
||
TIMEOUT_SECONDS = 5
|
||
|
||
|
||
def encode_name(name: str) -> bytes:
|
||
"""Encode a domain name as length-prefixed labels + null terminator."""
|
||
out = b""
|
||
for label in name.rstrip(".").split("."):
|
||
if len(label) > 63:
|
||
raise ValueError(f"DNS label too long: {label}")
|
||
out += bytes([len(label)]) + label.encode("ascii")
|
||
return out + b"\x00"
|
||
|
||
|
||
def build_notify(zone: str) -> bytes:
|
||
"""Build a DNS NOTIFY message for the given zone."""
|
||
txid = random.randint(0, 0xFFFF)
|
||
# Flags: QR=0, Opcode=4 (NOTIFY), AA=1, TC=0, RD=0, RA=0, Z=0, RCODE=0
|
||
# Layout: 0 0100 1 000 0 000 0000 → 0x2400
|
||
flags = (0 << 15) | (4 << 11) | (1 << 10) | 0
|
||
header = struct.pack(
|
||
">HHHHHH",
|
||
txid,
|
||
flags,
|
||
1, # QDCOUNT
|
||
0, # ANCOUNT
|
||
0, # NSCOUNT
|
||
0, # ARCOUNT
|
||
)
|
||
qname = encode_name(zone)
|
||
qtype = struct.pack(">H", 6) # SOA
|
||
qclass = struct.pack(">H", 1) # IN
|
||
return header + qname + qtype + qclass
|
||
|
||
|
||
def send_notify(zone: str, server: str) -> tuple[bool, str]:
|
||
"""Send NOTIFY for zone to server. Returns (ok, status_str)."""
|
||
pkt = build_notify(zone)
|
||
try:
|
||
with socket.socket(socket.AF_INET, socket.SOCK_DGRAM) as s:
|
||
s.settimeout(TIMEOUT_SECONDS)
|
||
s.sendto(pkt, (server, DNS_PORT))
|
||
data, _ = s.recvfrom(512)
|
||
if len(data) < 12:
|
||
return False, "short response"
|
||
# Parse flags from response header
|
||
_, rflags, _, _, _, _ = struct.unpack(">HHHHHH", data[:12])
|
||
opcode = (rflags >> 11) & 0xF
|
||
rcode = rflags & 0xF
|
||
if opcode != 4:
|
||
return False, f"opcode={opcode}"
|
||
if rcode != 0:
|
||
return False, f"rcode={rcode}"
|
||
return True, "ack"
|
||
except socket.timeout:
|
||
return False, "timeout"
|
||
except OSError as e:
|
||
return False, f"err: {e}"
|
||
|
||
|
||
def discover_zones(prepared_dir: Path) -> list[str]:
|
||
"""Return zone names from prepared zone filenames (foo.zone -> foo)."""
|
||
return sorted(f.stem for f in prepared_dir.glob("*.zone"))
|
||
|
||
|
||
def main() -> int:
|
||
prepared = Path(os.environ.get("DST_DIR", "zones-prepared"))
|
||
if not prepared.is_dir():
|
||
print(f"ERROR: prepared dir {prepared} not found", file=sys.stderr)
|
||
return 1
|
||
|
||
zones = discover_zones(prepared)
|
||
if not zones:
|
||
print(f"ERROR: no zones in {prepared}", file=sys.stderr)
|
||
return 1
|
||
|
||
quiet = "--quiet" in sys.argv
|
||
successes = failures = 0
|
||
for zone in zones:
|
||
zone_oks = []
|
||
for ns in HE_NAMESERVERS:
|
||
ok, status = send_notify(zone, ns)
|
||
if ok:
|
||
zone_oks.append(ns)
|
||
successes += 1
|
||
else:
|
||
if not quiet:
|
||
print(f" ✗ {zone:35s} → {ns:15s} {status}")
|
||
failures += 1
|
||
if zone_oks and not quiet:
|
||
print(f" ✓ {zone:35s} → {len(zone_oks)}/{len(HE_NAMESERVERS)} HE ns")
|
||
|
||
print(
|
||
f"NOTIFY summary: {successes} acks, {failures} fails "
|
||
f"across {len(zones)} zones × {len(HE_NAMESERVERS)} nameservers"
|
||
)
|
||
return 0 if failures == 0 else 2
|
||
|
||
|
||
if __name__ == "__main__":
|
||
sys.exit(main())
|