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https://github.com/Such-Software/adaptive-multi-protocol-gateway.git
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77c9e12e2d
Every Dynadot request this provider has ever made was rejected with "the X-Signature provided is not valid". The signature was correct. The header name was not. urllib capitalises header names when they go through add_header, which the Request constructor does for everything passed to it, so X-Request-ID left as X-request-id. Header names are case-insensitive under RFC 9110 and Dynadot's gateway is not: it matches X-Request-ID exactly, did not find the rewritten form, and computed the signature with an empty request id while we computed ours with the UUID. A correct signature over a different string, reported as a bad signature. That message sends you to the algorithm and the credentials, which is where I spent the evening. The header we were plainly sending is the last thing anyone would suspect. Assigning the mapping after construction bypasses add_header and preserves the name. Confirmed against the live API: exact X-Request-ID is accepted, and X-Request-Id one letter different is rejected. Two tests, both of which fail against the previous code: the wire name keeps its case, and the id in the signature is the id in the header. The second is the invariant that actually broke, and it can break again without the first. Co-authored-by: jw <jw@jwmacbookm5.local>
341 lines
12 KiB
Python
341 lines
12 KiB
Python
"""Guarded Dynadot REST v2 DNS provider.
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Dynadot updates replace the full zone and use one zone-wide TTL. The provider
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therefore models every documented record field and rejects lossy or mixed-TTL
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writes. Credentials are sent only in signed headers, never in URLs or output.
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"""
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from __future__ import annotations
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import base64
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import hashlib
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import hmac
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import ipaddress
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import json
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from pathlib import Path
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import urllib.error
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import urllib.parse
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import urllib.request
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import uuid
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from typing import Any, Callable
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from .dns import (
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DEFAULT_TTL,
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DNSZoneSnapshot,
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ProviderDNSRecord,
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_read_key_value_credentials,
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)
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DYNADOT_SUPPORTED_RECORD_TYPES = {
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"A",
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"AAAA",
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"ANAME",
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"CAA",
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"CNAME",
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"EMAIL",
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"FORWARD",
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"MX",
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"SRV",
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"STEALTH",
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"TXT",
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}
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DYNADOT_API_ORIGINS = {
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"https://api.dynadot.com",
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"https://api-sandbox.dynadot.com",
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}
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def dynadot_signature(
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api_key: str,
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api_secret: str,
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path_and_query: str,
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request_id: str,
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request_body: str = "",
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) -> str:
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message = "\n".join(
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(api_key, path_and_query, request_id or "", request_body or "")
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)
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digest = hmac.new(
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api_secret.encode("utf-8"),
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message.encode("utf-8"),
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hashlib.sha256,
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).digest()
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return base64.b64encode(digest).decode("ascii")
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def _validated_origin(value: str) -> str:
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parsed = urllib.parse.urlsplit(value.rstrip("/"))
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origin = f"{parsed.scheme}://{parsed.netloc}"
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if (
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origin not in DYNADOT_API_ORIGINS
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or parsed.path
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or parsed.query
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or parsed.fragment
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or parsed.username
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):
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raise ValueError("Dynadot api_base_url is not an approved HTTPS origin")
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return origin
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def _validated_source_cidr(value: str) -> str:
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try:
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network = ipaddress.ip_network(value, strict=True)
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except ValueError as error:
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raise ValueError("Dynadot allowed_source_cidr must be a valid CIDR") from error
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if network.version != 4 or network.prefixlen != 32:
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raise ValueError("Dynadot allowed_source_cidr must be an IPv4 /32")
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return str(network)
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def _required_mapping(value: Any, message: str) -> dict[str, Any]:
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if not isinstance(value, dict):
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raise RuntimeError(message)
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return value
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def _record_value(record: dict[str, Any], name: str) -> str | None:
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value = record.get(name)
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if value is None:
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return None
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if not isinstance(value, (str, int)):
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raise RuntimeError("Dynadot returned an unsupported DNS record shape")
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return str(value)
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class DynadotDNSProvider:
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name = "dynadot"
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backup_format = "json"
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def __init__(
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self,
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*,
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credentials: Path,
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opener: Callable[..., Any] | None = None,
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request_id_factory: Callable[[], str] | None = None,
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):
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config = _read_key_value_credentials(credentials)
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self.api_base_url = _validated_origin(
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config.get("api_base_url", "")
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)
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self.api_key = config.get("api_key")
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self.api_secret = config.get("api_secret")
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self.allowed_source_cidr = _validated_source_cidr(
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config.get("allowed_source_cidr", "")
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)
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if not self.api_key:
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raise ValueError(f"missing Dynadot api_key in {credentials}")
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if not self.api_secret:
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raise ValueError(f"missing Dynadot api_secret in {credentials}")
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self._opener = opener or urllib.request.urlopen
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self._request_id_factory = request_id_factory or (
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lambda: str(uuid.uuid4())
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)
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def get_hosts(self, domain: str) -> DNSZoneSnapshot:
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response = self._request("GET", self._records_path(domain))
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data = _required_mapping(
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response.get("data"), "Dynadot DNS response omitted data"
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)
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glue = _required_mapping(
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data.get("glue_info"), "Dynadot DNS response omitted glue_info"
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)
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glue_type = str(glue.get("glue_type", "")).upper()
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if glue_type and glue_type != "DNS":
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raise RuntimeError("Dynadot zone is not using Dynadot DNS")
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ttl = glue.get("ttl", DEFAULT_TTL)
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if not isinstance(ttl, int) or ttl < 60 or ttl > 86400:
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raise RuntimeError("Dynadot returned an invalid zone TTL")
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records: list[ProviderDNSRecord] = []
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for field, name_field in (
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("dns_main_list", None),
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("dns_sub_list", "sub_host"),
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):
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raw_records = glue.get(field, [])
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if not isinstance(raw_records, list):
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raise RuntimeError("Dynadot returned an unsupported DNS record list")
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for raw_record in raw_records:
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item = _required_mapping(
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raw_record, "Dynadot returned an unsupported DNS record"
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)
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record_type = str(item.get("record_type", "")).upper()
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if record_type not in DYNADOT_SUPPORTED_RECORD_TYPES:
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raise RuntimeError(
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"Dynadot returned an unsupported DNS record type"
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)
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name = "@" if name_field is None else _record_value(item, name_field)
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value1 = _record_value(item, "value1")
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value2 = _record_value(item, "value2")
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if not name or value1 is None:
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raise RuntimeError("Dynadot returned an incomplete DNS record")
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mx_pref = None
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provider_value2 = value2
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if record_type == "MX":
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try:
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mx_pref = int(value2) if value2 is not None else None
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except ValueError as error:
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raise RuntimeError(
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"Dynadot returned an invalid MX preference"
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) from error
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if mx_pref is None or not 0 <= mx_pref <= 65535:
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raise RuntimeError("Dynadot returned an invalid MX preference")
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provider_value2 = None
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records.append(
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ProviderDNSRecord(
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name=name,
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type=record_type,
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value=value1,
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ttl=ttl,
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mx_pref=mx_pref,
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provider_value2=provider_value2,
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)
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)
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raw = json.dumps(response, indent=2, sort_keys=True) + "\n"
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return DNSZoneSnapshot(
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self.name,
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domain,
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raw,
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tuple(records),
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"ok",
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"zone fetched from Dynadot",
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ttl,
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)
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def set_hosts(
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self,
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domain: str,
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records: tuple[ProviderDNSRecord, ...],
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*,
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mail_policy: str,
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) -> None:
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if mail_policy != "preserve":
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raise ValueError("Dynadot full-zone updates require mail_policy=preserve")
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if not records:
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raise ValueError("refusing to replace a Dynadot zone with no records")
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ttls = {int(record.ttl) for record in records}
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if len(ttls) != 1:
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raise ValueError("Dynadot full-zone updates require one observed zone TTL")
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ttl = next(iter(ttls))
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if ttl < 60 or ttl > 86400:
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raise ValueError("Dynadot zone TTL is invalid")
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main: list[dict[str, str]] = []
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sub: list[dict[str, str]] = []
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for record in records:
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record_type = record.type.upper()
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if record_type not in DYNADOT_SUPPORTED_RECORD_TYPES:
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raise ValueError("Dynadot record type is unsupported")
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item = {
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"record_type": record_type,
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"value1": record.value,
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}
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value2 = (
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str(record.mx_pref)
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if record_type == "MX"
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else record.provider_value2
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)
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if record_type == "MX" and record.mx_pref is None:
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raise ValueError("Dynadot MX records require mx_pref")
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if value2 is not None:
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item["value2"] = value2
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normalized_name = record.name.strip().rstrip(".").lower() or "@"
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if normalized_name == "@":
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main.append(item)
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else:
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item["sub_host"] = normalized_name
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sub.append(item)
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if len(main) > 20 or len(sub) > 100:
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raise ValueError("Dynadot zone exceeds documented record limits")
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body = {
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"dns_main_list": main,
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"dns_sub_list": sub,
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"ttl": ttl,
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"add_dns_to_current_setting": False,
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}
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self._request("POST", self._records_path(domain), body)
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@staticmethod
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def _records_path(domain: str) -> str:
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normalized = domain.strip().rstrip(".").lower()
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if not normalized or "/" in normalized:
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raise ValueError("invalid Dynadot domain")
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return "/restful/v2/domains/" + urllib.parse.quote(normalized) + "/records"
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def _request(
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self,
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method: str,
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path: str,
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body: dict[str, Any] | None = None,
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) -> dict[str, Any]:
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request_body = (
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json.dumps(body, sort_keys=True, separators=(",", ":"))
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if body is not None
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else ""
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)
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request_id = self._request_id_factory()
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headers = {
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"Accept": "application/json",
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"Authorization": f"Bearer {self.api_key}",
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"Content-Type": "application/json",
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"X-Request-ID": request_id,
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"X-Signature": dynadot_signature(
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self.api_key,
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self.api_secret,
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path,
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request_id,
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request_body,
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),
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}
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request = urllib.request.Request(
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self.api_base_url + path,
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data=request_body.encode("utf-8") if body is not None else None,
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method=method,
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)
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# Assigned rather than passed to the constructor, which routes every
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# header through add_header() and capitalises the name: X-Request-ID
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# becomes X-request-id on the wire.
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#
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# Header names are case-insensitive per RFC 9110, and Dynadot's gateway
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# is not. It matches X-Request-ID exactly, does not find the rewritten
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# form, and therefore computes the signature with an empty request id
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# while we computed ours with the UUID. The result is a valid signature
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# over a different string, reported as "the X-Signature provided is not
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# valid", which points at the algorithm and the credentials rather than
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# at a header we did send.
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request.headers = headers
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try:
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with self._opener(request, timeout=30) as response:
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raw = response.read().decode("utf-8")
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except urllib.error.HTTPError as error:
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# Dynadot explains the refusal in the body. Discarding it left the
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# operator with a status code and nothing to act on, which for a 400
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# is the difference between "the domain is not in this account" and
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# "the signature is wrong". Bounded and quoted because it is remote
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# text, and the credential is never in it: the key travels in a
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# header and the signature is computed, not echoed.
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detail = ""
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try:
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body = error.read().decode("utf-8", "replace").strip()
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if body:
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detail = f": {body[:400]}"
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except Exception: # noqa: BLE001 - a body is a bonus, never required
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detail = ""
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raise RuntimeError(
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f"Dynadot API rejected {method} {path} with HTTP {error.code}{detail}"
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) from error
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except urllib.error.URLError as error:
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raise RuntimeError(
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f"Dynadot API connectivity failed for {method} {path}"
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) from error
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try:
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document = json.loads(raw)
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except json.JSONDecodeError as error:
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raise RuntimeError("Dynadot API returned non-JSON data") from error
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if not isinstance(document, dict):
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raise RuntimeError("Dynadot API returned an unsupported response")
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code = document.get("code")
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if code is not None and str(code) not in {"200", "201", "0"}:
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raise RuntimeError(f"Dynadot API rejected {method} {path}")
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if document.get("success") is False:
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raise RuntimeError(f"Dynadot API rejected {method} {path}")
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return document
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