Add generic endpoint list parsing

dns_sync/config.py

@@ -1,9 +1,84 @@
 import os
 from dataclasses import dataclass
+from urllib.parse import urlsplit
 
+from .adapters import Endpoint
 from .normalizer import normalize_hostname, normalize_ipv4
 
 
+def parse_endpoint_list(
+    plugin: str,
+    value: str,
+    default_port: int,
+) -> tuple[Endpoint, ...]:
+    if not 1 <= default_port <= 65535:
+        raise RuntimeError(
+            "Endpoint default port must be between 1 and 65535"
+        )
+
+    raw_addresses = value.split(",")
+    if any(not item.strip() for item in raw_addresses):
+        raise RuntimeError(
+            f"{plugin.upper()} endpoint list contains an empty address"
+        )
+
+    endpoints: list[Endpoint] = []
+    identities: set[str] = set()
+
+    for raw_address in raw_addresses:
+        address = raw_address.strip().rstrip("/")
+
+        if "://" in address:
+            raise RuntimeError(
+                f"{plugin.upper()} endpoint {raw_address!r} must not "
+                "include a URL scheme"
+            )
+
+        if any(character.isspace() for character in address):
+            raise RuntimeError(
+                f"{plugin.upper()} endpoint {raw_address!r} "
+                "contains whitespace"
+            )
+
+        parsed = urlsplit(f"//{address}")
+        if (
+            not parsed.hostname
+            or parsed.username
+            or parsed.password
+            or parsed.path
+            or parsed.query
+            or parsed.fragment
+        ):
+            raise RuntimeError(
+                f"Invalid {plugin.upper()} endpoint address: "
+                f"{raw_address!r}"
+            )
+
+        try:
+            port = parsed.port or default_port
+        except ValueError as exc:
+            raise RuntimeError(
+                f"Invalid {plugin.upper()} endpoint port: "
+                f"{raw_address!r}"
+            ) from exc
+
+        host = parsed.hostname.lower()
+        normalized_address = (
+            f"[{host}]:{port}" if ":" in host else f"{host}:{port}"
+        )
+        endpoint = Endpoint(plugin, normalized_address)
+
+        if endpoint.identity in identities:
+            raise RuntimeError(
+                f"Duplicate {plugin.upper()} endpoint: {endpoint.address}"
+            )
+
+        identities.add(endpoint.identity)
+        endpoints.append(endpoint)
+
+    return tuple(endpoints)
+
+
 def env_bool(name: str, default: bool) -> bool:
     value = os.getenv(name)
     if value is None: