Initial commit for new v2

app/webfinger.py

@@ -0,0 +1,79 @@
+from typing import Any
+from urllib.parse import urlparse
+
+import httpx
+from loguru import logger
+
+from app import activitypub as ap
+
+
+def webfinger(
+    resource: str,
+) -> dict[str, Any] | None:  # noqa: C901
+    """Mastodon-like WebFinger resolution to retrieve the activity stream Actor URL."""
+    logger.info(f"performing webfinger resolution for {resource}")
+    protos = ["https", "http"]
+    if resource.startswith("http://"):
+        protos.reverse()
+        host = urlparse(resource).netloc
+    elif resource.startswith("https://"):
+        host = urlparse(resource).netloc
+    else:
+        if resource.startswith("acct:"):
+            resource = resource[5:]
+        if resource.startswith("@"):
+            resource = resource[1:]
+        _, host = resource.split("@", 1)
+        resource = "acct:" + resource
+
+    is_404 = False
+
+    for i, proto in enumerate(protos):
+        try:
+            url = f"{proto}://{host}/.well-known/webfinger"
+            resp = ap.get(url, params={"resource": resource})
+            break
+        except httpx.HTTPStatusError as http_error:
+            logger.exception("HTTP error")
+            if http_error.response.status_code in [403, 404, 410]:
+                is_404 = True
+                continue
+            raise
+        except httpx.HTTPError:
+            logger.exception("req failed")
+            # If we tried https first and the domain is "http only"
+            if i == 0:
+                continue
+            break
+    if is_404:
+        return None
+
+    return resp
+
+
+def get_remote_follow_template(resource: str) -> str | None:
+    data = webfinger(resource)
+    if data is None:
+        return None
+    for link in data["links"]:
+        if link.get("rel") == "http://ostatus.org/schema/1.0/subscribe":
+            return link.get("template")
+    return None
+
+
+def get_actor_url(resource: str) -> str | None:
+    """Mastodon-like WebFinger resolution to retrieve the activity stream Actor URL.
+
+    Returns:
+        the Actor URL or None if the resolution failed.
+    """
+    data = webfinger(resource)
+    if data is None:
+        return None
+    for link in data["links"]:
+        if (
+            link.get("rel") == "self"
+            and link.get("type") == "application/activity+json"
+        ):
+            return link.get("href")
+    return None