Files
adaptive-multi-protocol-gat…/ampg/dynadot_dns.py
T
jw b5df743fbb Surface Dynadot's refusal instead of only its status code
A 400 from Dynadot arrived as "HTTP 400" and nothing else. Dynadot explains the
refusal in the response body and we were discarding it, so the operator was left
with a number that does not distinguish "the domain is not in this account" from
"the signature is wrong" from "the caller address is not allowlisted". All three
are 400 and all three have different fixes.

The body is bounded to 400 characters and quoted as remote text. No credential
can appear in it: the key travels in an Authorization header and the signature
is computed rather than echoed.

Reading the body is best-effort. A stream that cannot be read must not cost the
status code as well, so the failure to read is swallowed and the code is still
raised, which is what the second test pins.
2026-08-24 09:01:33 -04:00

330 lines
12 KiB
Python

"""Guarded Dynadot REST v2 DNS provider.
Dynadot updates replace the full zone and use one zone-wide TTL. The provider
therefore models every documented record field and rejects lossy or mixed-TTL
writes. Credentials are sent only in signed headers, never in URLs or output.
"""
from __future__ import annotations
import base64
import hashlib
import hmac
import ipaddress
import json
from pathlib import Path
import urllib.error
import urllib.parse
import urllib.request
import uuid
from typing import Any, Callable
from .dns import (
DEFAULT_TTL,
DNSZoneSnapshot,
ProviderDNSRecord,
_read_key_value_credentials,
)
DYNADOT_SUPPORTED_RECORD_TYPES = {
"A",
"AAAA",
"ANAME",
"CAA",
"CNAME",
"EMAIL",
"FORWARD",
"MX",
"SRV",
"STEALTH",
"TXT",
}
DYNADOT_API_ORIGINS = {
"https://api.dynadot.com",
"https://api-sandbox.dynadot.com",
}
def dynadot_signature(
api_key: str,
api_secret: str,
path_and_query: str,
request_id: str,
request_body: str = "",
) -> str:
message = "\n".join(
(api_key, path_and_query, request_id or "", request_body or "")
)
digest = hmac.new(
api_secret.encode("utf-8"),
message.encode("utf-8"),
hashlib.sha256,
).digest()
return base64.b64encode(digest).decode("ascii")
def _validated_origin(value: str) -> str:
parsed = urllib.parse.urlsplit(value.rstrip("/"))
origin = f"{parsed.scheme}://{parsed.netloc}"
if (
origin not in DYNADOT_API_ORIGINS
or parsed.path
or parsed.query
or parsed.fragment
or parsed.username
):
raise ValueError("Dynadot api_base_url is not an approved HTTPS origin")
return origin
def _validated_source_cidr(value: str) -> str:
try:
network = ipaddress.ip_network(value, strict=True)
except ValueError as error:
raise ValueError("Dynadot allowed_source_cidr must be a valid CIDR") from error
if network.version != 4 or network.prefixlen != 32:
raise ValueError("Dynadot allowed_source_cidr must be an IPv4 /32")
return str(network)
def _required_mapping(value: Any, message: str) -> dict[str, Any]:
if not isinstance(value, dict):
raise RuntimeError(message)
return value
def _record_value(record: dict[str, Any], name: str) -> str | None:
value = record.get(name)
if value is None:
return None
if not isinstance(value, (str, int)):
raise RuntimeError("Dynadot returned an unsupported DNS record shape")
return str(value)
class DynadotDNSProvider:
name = "dynadot"
backup_format = "json"
def __init__(
self,
*,
credentials: Path,
opener: Callable[..., Any] | None = None,
request_id_factory: Callable[[], str] | None = None,
):
config = _read_key_value_credentials(credentials)
self.api_base_url = _validated_origin(
config.get("api_base_url", "")
)
self.api_key = config.get("api_key")
self.api_secret = config.get("api_secret")
self.allowed_source_cidr = _validated_source_cidr(
config.get("allowed_source_cidr", "")
)
if not self.api_key:
raise ValueError(f"missing Dynadot api_key in {credentials}")
if not self.api_secret:
raise ValueError(f"missing Dynadot api_secret in {credentials}")
self._opener = opener or urllib.request.urlopen
self._request_id_factory = request_id_factory or (
lambda: str(uuid.uuid4())
)
def get_hosts(self, domain: str) -> DNSZoneSnapshot:
response = self._request("GET", self._records_path(domain))
data = _required_mapping(
response.get("data"), "Dynadot DNS response omitted data"
)
glue = _required_mapping(
data.get("glue_info"), "Dynadot DNS response omitted glue_info"
)
glue_type = str(glue.get("glue_type", "")).upper()
if glue_type and glue_type != "DNS":
raise RuntimeError("Dynadot zone is not using Dynadot DNS")
ttl = glue.get("ttl", DEFAULT_TTL)
if not isinstance(ttl, int) or ttl < 60 or ttl > 86400:
raise RuntimeError("Dynadot returned an invalid zone TTL")
records: list[ProviderDNSRecord] = []
for field, name_field in (
("dns_main_list", None),
("dns_sub_list", "sub_host"),
):
raw_records = glue.get(field, [])
if not isinstance(raw_records, list):
raise RuntimeError("Dynadot returned an unsupported DNS record list")
for raw_record in raw_records:
item = _required_mapping(
raw_record, "Dynadot returned an unsupported DNS record"
)
record_type = str(item.get("record_type", "")).upper()
if record_type not in DYNADOT_SUPPORTED_RECORD_TYPES:
raise RuntimeError(
"Dynadot returned an unsupported DNS record type"
)
name = "@" if name_field is None else _record_value(item, name_field)
value1 = _record_value(item, "value1")
value2 = _record_value(item, "value2")
if not name or value1 is None:
raise RuntimeError("Dynadot returned an incomplete DNS record")
mx_pref = None
provider_value2 = value2
if record_type == "MX":
try:
mx_pref = int(value2) if value2 is not None else None
except ValueError as error:
raise RuntimeError(
"Dynadot returned an invalid MX preference"
) from error
if mx_pref is None or not 0 <= mx_pref <= 65535:
raise RuntimeError("Dynadot returned an invalid MX preference")
provider_value2 = None
records.append(
ProviderDNSRecord(
name=name,
type=record_type,
value=value1,
ttl=ttl,
mx_pref=mx_pref,
provider_value2=provider_value2,
)
)
raw = json.dumps(response, indent=2, sort_keys=True) + "\n"
return DNSZoneSnapshot(
self.name,
domain,
raw,
tuple(records),
"ok",
"zone fetched from Dynadot",
ttl,
)
def set_hosts(
self,
domain: str,
records: tuple[ProviderDNSRecord, ...],
*,
mail_policy: str,
) -> None:
if mail_policy != "preserve":
raise ValueError("Dynadot full-zone updates require mail_policy=preserve")
if not records:
raise ValueError("refusing to replace a Dynadot zone with no records")
ttls = {int(record.ttl) for record in records}
if len(ttls) != 1:
raise ValueError("Dynadot full-zone updates require one observed zone TTL")
ttl = next(iter(ttls))
if ttl < 60 or ttl > 86400:
raise ValueError("Dynadot zone TTL is invalid")
main: list[dict[str, str]] = []
sub: list[dict[str, str]] = []
for record in records:
record_type = record.type.upper()
if record_type not in DYNADOT_SUPPORTED_RECORD_TYPES:
raise ValueError("Dynadot record type is unsupported")
item = {
"record_type": record_type,
"value1": record.value,
}
value2 = (
str(record.mx_pref)
if record_type == "MX"
else record.provider_value2
)
if record_type == "MX" and record.mx_pref is None:
raise ValueError("Dynadot MX records require mx_pref")
if value2 is not None:
item["value2"] = value2
normalized_name = record.name.strip().rstrip(".").lower() or "@"
if normalized_name == "@":
main.append(item)
else:
item["sub_host"] = normalized_name
sub.append(item)
if len(main) > 20 or len(sub) > 100:
raise ValueError("Dynadot zone exceeds documented record limits")
body = {
"dns_main_list": main,
"dns_sub_list": sub,
"ttl": ttl,
"add_dns_to_current_setting": False,
}
self._request("POST", self._records_path(domain), body)
@staticmethod
def _records_path(domain: str) -> str:
normalized = domain.strip().rstrip(".").lower()
if not normalized or "/" in normalized:
raise ValueError("invalid Dynadot domain")
return "/restful/v2/domains/" + urllib.parse.quote(normalized) + "/records"
def _request(
self,
method: str,
path: str,
body: dict[str, Any] | None = None,
) -> dict[str, Any]:
request_body = (
json.dumps(body, sort_keys=True, separators=(",", ":"))
if body is not None
else ""
)
request_id = self._request_id_factory()
headers = {
"Accept": "application/json",
"Authorization": f"Bearer {self.api_key}",
"Content-Type": "application/json",
"X-Request-ID": request_id,
"X-Signature": dynadot_signature(
self.api_key,
self.api_secret,
path,
request_id,
request_body,
),
}
request = urllib.request.Request(
self.api_base_url + path,
data=request_body.encode("utf-8") if body is not None else None,
headers=headers,
method=method,
)
try:
with self._opener(request, timeout=30) as response:
raw = response.read().decode("utf-8")
except urllib.error.HTTPError as error:
# Dynadot explains the refusal in the body. Discarding it left the
# operator with a status code and nothing to act on, which for a 400
# is the difference between "the domain is not in this account" and
# "the signature is wrong". Bounded and quoted because it is remote
# text, and the credential is never in it: the key travels in a
# header and the signature is computed, not echoed.
detail = ""
try:
body = error.read().decode("utf-8", "replace").strip()
if body:
detail = f": {body[:400]}"
except Exception: # noqa: BLE001 - a body is a bonus, never required
detail = ""
raise RuntimeError(
f"Dynadot API rejected {method} {path} with HTTP {error.code}{detail}"
) from error
except urllib.error.URLError as error:
raise RuntimeError(
f"Dynadot API connectivity failed for {method} {path}"
) from error
try:
document = json.loads(raw)
except json.JSONDecodeError as error:
raise RuntimeError("Dynadot API returned non-JSON data") from error
if not isinstance(document, dict):
raise RuntimeError("Dynadot API returned an unsupported response")
code = document.get("code")
if code is not None and str(code) not in {"200", "201", "0"}:
raise RuntimeError(f"Dynadot API rejected {method} {path}")
if document.get("success") is False:
raise RuntimeError(f"Dynadot API rejected {method} {path}")
return document