1 files changed, 15 insertions, 13 deletions
diff --git a/webmentions_ssg/url_security.py b/webmentions_ssg/url_security.py
index ce5d700..51c037a 100644
--- a/webmentions_ssg/url_security.py
+++ b/webmentions_ssg/url_security.py
@@ -9,15 +9,11 @@ class AddressResolutionError(Exception):
     pass
 
 
-class NonPublicAddressError(Exception):
-    pass
-
-
-def ensure_public_url(url: str) -> None:
+def is_public_url(url: str) -> bool:
     hostname = urlsplit(url).hostname
 
     if hostname is None:
-        raise NonPublicAddressError("URL has no hostname")
+        raise ValueError("No hostname was specified")
 
     try:
         answers = dns.resolver.resolve_name(hostname)
@@ -25,13 +21,19 @@ def ensure_public_url(url: str) -> None:
         raise AddressResolutionError(
             f"Could not resolve hostname {hostname!r}"
         ) from exc
+    else:
+        for address in answers.addresses():
+            if not ipaddress.ip_address(address).is_global:
+                return False
 
-    addresses = {ipaddress.ip_address(address) for address in answers.addresses()}
+        return True
 
-    if not addresses:
-        raise AddressResolutionError(f"Hostname {hostname!r} did not resolve")
 
-    if any(not address.is_global for address in addresses):
-        raise NonPublicAddressError(
-            f"Hostname {hostname!r} resolves to a non-public address"
-        )
+def is_http_url(url: str) -> bool:
+    """Return whether a URL is an absolute HTTP or HTTPS URL."""
+    try:
+        parsed = urlsplit(url)
+    except ValueError:
+        return False
+
+    return parsed.scheme.lower() in {"http", "https"} and parsed.hostname is not None