kurogeek
d623ef8470
Replace the static prefix+extension numbering with random 6 digit box numbers (100000-999999) signed by the machine's yggdrasil key. A serf gossip cluster on yggdrasil port 7946 exchanges the signed records; phonebox-sync verifies key -> address derivation and the signature and writes the number -> address map to /run/phonebox/numbers for the asterisk dialplan. Any yggdrasil node running the service can reach any other; clan-core's ygg-input filter is opened for SIP, RTP and gossip. Drop the server-prefix-number and ata-local-number vars, add a two-node VM test that proves directory convergence and a call over yggdrasil.
112 lines
4.2 KiB
Python
112 lines
4.2 KiB
Python
"""Rebuild the phonebox number directory from serf membership.
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Usage: phonebox-sync <serf rpc addr> <state dir>
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Runs as a serf event handler. Every alive member carries its number record
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as tags (number, key, sig, owner). A record is accepted only when the
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yggdrasil address it is gossiped from derives from `key` and `sig` is a
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valid ed25519 signature of "phonebox:<number>" under that key, so a number
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can only ever be bound to the address of the node that signed it.
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Output, consumed by the asterisk dialplan:
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<state dir>/numbers/<number> the yggdrasil address, no trailing newline
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<state dir>/contacts.txt "<number> : <owner>" per line, for the fax
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"""
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import base64
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import ipaddress
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import json
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import os
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import subprocess
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import sys
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import syslog
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import tempfile
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from cryptography.exceptions import InvalidSignature
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from cryptography.hazmat.primitives.asymmetric.ed25519 import Ed25519PublicKey
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def yggdrasil_address(public_key: bytes) -> ipaddress.IPv6Address:
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"""Port of yggdrasil-go address.AddrForKey.
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Invert the key; the address is 0x02, the count of leading one bits,
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then the bits following the first zero, truncated to 128 bits.
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"""
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bits = "".join(f"{b ^ 0xFF:08b}" for b in public_key)
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ones = len(bits) - len(bits.lstrip("1"))
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body = int(bits[ones + 1:ones + 113], 2).to_bytes(14, "big")
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return ipaddress.IPv6Address(bytes([0x02, ones]) + body)
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def verified_record(member: dict) -> tuple[str, str, str, str]:
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"""Return (number, key hex, address, owner) or raise ValueError."""
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tags = member.get("tags", {})
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try:
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number, key_hex, sig = tags["number"], tags["key"], tags["sig"]
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key = bytes.fromhex(key_hex)
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host, _ = member["addr"].rsplit(":", 1)
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address = ipaddress.IPv6Address(host.strip("[]"))
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signature = base64.b64decode(sig, validate=True)
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except (KeyError, ValueError) as e:
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raise ValueError(f"malformed record: {e}")
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if not (len(number) == 6 and number.isdigit() and number[0] != "0"):
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raise ValueError(f"invalid number {number!r}")
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if yggdrasil_address(key) != address:
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raise ValueError(f"key does not derive to address {address}")
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try:
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Ed25519PublicKey.from_public_bytes(key).verify(signature, b"phonebox:" + number.encode())
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except (ValueError, InvalidSignature):
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raise ValueError(f"bad signature for number {number}")
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return number, key_hex, str(address), tags.get("owner", "")
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def directory(members: list[dict]) -> dict[str, tuple[str, str, str]]:
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"""number -> (key hex, address, owner); on a collision the lowest key wins."""
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book = {}
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for member in members:
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try:
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number, key, address, owner = verified_record(member)
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except ValueError as e:
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syslog.syslog(syslog.LOG_WARNING, f"ignoring {member.get('name')}: {e}")
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continue
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if number in book:
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syslog.syslog(syslog.LOG_WARNING, f"number {number} claimed by keys {book[number][0]} and {key}")
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if book[number][0] <= key:
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continue
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book[number] = (key, address, owner)
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return book
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def write_atomic(path: str, content: str) -> None:
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fd, tmp = tempfile.mkstemp(dir=os.path.dirname(path))
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with os.fdopen(fd, "w") as f:
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f.write(content)
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os.chmod(tmp, 0o644)
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os.replace(tmp, path)
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def main() -> None:
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rpc_addr, state_dir = sys.argv[1:]
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syslog.openlog("phonebox-sync")
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out = subprocess.run(
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["serf", "members", "-format=json", "-status=alive", f"-rpc-addr={rpc_addr}"],
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check=True, capture_output=True, text=True,
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).stdout
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book = directory(json.loads(out)["members"])
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numbers_dir = os.path.join(state_dir, "numbers")
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os.makedirs(numbers_dir, exist_ok=True)
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for number, (_, address, _) in book.items():
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write_atomic(os.path.join(numbers_dir, number), address)
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for stale in set(os.listdir(numbers_dir)) - book.keys():
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os.unlink(os.path.join(numbers_dir, stale))
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write_atomic(
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os.path.join(state_dir, "contacts.txt"),
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"".join(f"{number}\t\t: \t\t{book[number][2]}\n" for number in sorted(book)),
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)
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syslog.syslog(syslog.LOG_INFO, f"directory has {len(book)} numbers")
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if __name__ == "__main__":
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main()
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