microblog.pub/utils/lookup.py
2019-09-08 12:09:34 +02:00

54 lines
1.8 KiB
Python

import little_boxes.activitypub as ap
import mf2py
import requests
from little_boxes.errors import NotAnActivityError
from little_boxes.errors import RemoteServerUnavailableError
from little_boxes.webfinger import get_actor_url
def lookup(url: str) -> ap.BaseActivity:
"""Try to find an AP object related to the given URL."""
try:
if url.startswith("@"):
actor_url = get_actor_url(url)
if actor_url:
return ap.fetch_remote_activity(actor_url)
except NotAnActivityError:
pass
except requests.HTTPError:
# Some websites may returns 404, 503 or others when they don't support webfinger, and we're just taking a guess
# when performing the lookup.
pass
except requests.RequestException as err:
raise RemoteServerUnavailableError(f"failed to fetch {url}: {err!r}")
backend = ap.get_backend()
try:
resp = requests.head(
url,
timeout=10,
allow_redirects=True,
headers={"User-Agent": backend.user_agent()},
)
except requests.RequestException as err:
raise RemoteServerUnavailableError(f"failed to GET {url}: {err!r}")
try:
resp.raise_for_status()
except Exception:
return ap.fetch_remote_activity(url)
# If the page is HTML, maybe it contains an alternate link pointing to an AP object
for alternate in mf2py.parse(resp.text).get("alternates", []):
if alternate.get("type") == "application/activity+json":
return ap.fetch_remote_activity(alternate["url"])
try:
# Maybe the page was JSON-LD?
data = resp.json()
return ap.parse_activity(data)
except Exception:
pass
# Try content negotiation (retry with the AP Accept header)
return ap.fetch_remote_activity(url)