Build KarlDNS self-hosted DynDNS service

router_dyndns/web/forms.py

@@ -0,0 +1,31 @@
+from __future__ import annotations
+
+import urllib.parse
+
+from fastapi import HTTPException, Request
+
+from ..ddns_models import DdnsSettings
+
+MAX_FORM_FIELDS = 100
+
+
+def parse_form(body: bytes) -> dict[str, list[str]]:
+    try:
+        decoded = body.decode("utf-8")
+    except UnicodeDecodeError as exc:
+        raise HTTPException(status_code=400, detail="form body must be valid UTF-8") from exc
+    try:
+        return urllib.parse.parse_qs(decoded, keep_blank_values=True, max_num_fields=MAX_FORM_FIELDS)
+    except ValueError as exc:
+        raise HTTPException(status_code=400, detail=f"form must not contain more than {MAX_FORM_FIELDS} fields") from exc
+
+
+async def request_form(request: Request, settings: DdnsSettings) -> dict[str, list[str]]:
+    body = await request.body()
+    if len(body) > settings.max_request_body_bytes:
+        raise HTTPException(status_code=413, detail="request body too large")
+    return parse_form(body)
+
+
+def first_form_value(form: dict[str, list[str]], key: str) -> str:
+    return form.get(key, [""])[0].strip()