mirror of
https://git.sr.ht/~tsileo/microblog.pub
synced 2024-11-14 18:54:27 +00:00
45 lines
1.2 KiB
Python
45 lines
1.2 KiB
Python
import base64
|
|
import time
|
|
|
|
from app.config import BASE_URL
|
|
from app.config import hmac_sha256
|
|
|
|
SUPPORTED_RESIZE = [50, 740]
|
|
EXPIRY_PERIOD = 86400
|
|
EXPIRY_LENGTH = 7
|
|
|
|
|
|
class InvalidProxySignatureError(Exception):
|
|
pass
|
|
|
|
|
|
def proxied_media_sig(expires: int, url: str) -> str:
|
|
hm = hmac_sha256()
|
|
hm.update(f'{expires}'.encode())
|
|
hm.update(b'|')
|
|
hm.update(url.encode())
|
|
return base64.urlsafe_b64encode(hm.digest()).decode()
|
|
|
|
|
|
def verify_proxied_media_sig(expires: int, url: str, sig: str) -> None:
|
|
now = int(time.time() / EXPIRY_PERIOD)
|
|
expected = proxied_media_sig(expires, url)
|
|
if now > expires or sig != expected:
|
|
raise InvalidProxySignatureError("invalid or expired media")
|
|
|
|
|
|
def proxied_media_url(url: str) -> str:
|
|
if url.startswith(BASE_URL):
|
|
return url
|
|
expires = int(time.time() / EXPIRY_PERIOD) + EXPIRY_LENGTH
|
|
sig = proxied_media_sig(expires, url)
|
|
|
|
return BASE_URL + f"/proxy/media/{expires}/{sig}/" + base64.urlsafe_b64encode(url.encode()).decode()
|
|
|
|
|
|
def resized_media_url(url: str, size: int) -> str:
|
|
if size not in SUPPORTED_RESIZE:
|
|
raise ValueError(f"Unsupported resize {size}")
|
|
if url.startswith(BASE_URL):
|
|
return url
|
|
return proxied_media_url(url) + f"/{size}"
|