302 lines
11 KiB
Python
302 lines
11 KiB
Python
import base64
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import uuid
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from functools import partial
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from typing import Optional, Tuple
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from urllib.parse import urlparse
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import httpx
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import urlman
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from asgiref.sync import sync_to_async
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from cryptography.hazmat.primitives import hashes, serialization
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from cryptography.hazmat.primitives.asymmetric import padding, rsa
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from django.db import models
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from django.utils import timezone
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from django.utils.http import http_date
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from OpenSSL import crypto
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from core.ld import canonicalise
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from users.models.domain import Domain
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def upload_namer(prefix, instance, filename):
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"""
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Names uploaded images etc.
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"""
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now = timezone.now()
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filename = base64.b32encode(uuid.uuid4().bytes).decode("ascii")
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return f"{prefix}/{now.year}/{now.month}/{now.day}/{filename}"
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class Identity(models.Model):
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"""
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Represents both local and remote Fediverse identities (actors)
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"""
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# The Actor URI is essentially also a PK - we keep the default numeric
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# one around as well for making nice URLs etc.
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actor_uri = models.CharField(max_length=500, blank=True, null=True, unique=True)
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local = models.BooleanField()
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users = models.ManyToManyField("users.User", related_name="identities")
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username = models.CharField(max_length=500, blank=True, null=True)
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# Must be a display domain if present
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domain = models.ForeignKey(
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"users.Domain",
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blank=True,
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null=True,
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on_delete=models.PROTECT,
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)
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name = models.CharField(max_length=500, blank=True, null=True)
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summary = models.TextField(blank=True, null=True)
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manually_approves_followers = models.BooleanField(blank=True, null=True)
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profile_uri = models.CharField(max_length=500, blank=True, null=True)
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inbox_uri = models.CharField(max_length=500, blank=True, null=True)
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outbox_uri = models.CharField(max_length=500, blank=True, null=True)
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icon_uri = models.CharField(max_length=500, blank=True, null=True)
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image_uri = models.CharField(max_length=500, blank=True, null=True)
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icon = models.ImageField(
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upload_to=partial(upload_namer, "profile_images"), blank=True, null=True
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)
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image = models.ImageField(
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upload_to=partial(upload_namer, "background_images"), blank=True, null=True
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)
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private_key = models.TextField(null=True, blank=True)
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public_key = models.TextField(null=True, blank=True)
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created = models.DateTimeField(auto_now_add=True)
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updated = models.DateTimeField(auto_now=True)
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fetched = models.DateTimeField(null=True, blank=True)
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deleted = models.DateTimeField(null=True, blank=True)
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class Meta:
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verbose_name_plural = "identities"
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unique_together = [("username", "domain")]
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@classmethod
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def by_handle(cls, handle, fetch=False, local=False):
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if handle.startswith("@"):
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raise ValueError("Handle must not start with @")
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if "@" not in handle:
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raise ValueError("Handle must contain domain")
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username, domain = handle.split("@")
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try:
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if local:
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return cls.objects.get(username=username, domain_id=domain, local=True)
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else:
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return cls.objects.get(username=username, domain_id=domain)
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except cls.DoesNotExist:
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if fetch and not local:
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return cls.objects.create(handle=handle, local=False)
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return None
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@classmethod
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def by_actor_uri(cls, uri) -> Optional["Identity"]:
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try:
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return cls.objects.get(actor_uri=uri)
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except cls.DoesNotExist:
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return None
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@classmethod
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def by_actor_uri_with_create(cls, uri) -> "Identity":
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try:
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return cls.objects.get(actor_uri=uri)
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except cls.DoesNotExist:
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return cls.objects.create(actor_uri=uri, local=False)
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@property
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def handle(self):
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return f"{self.username}@{self.domain_id}"
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@property
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def data_age(self) -> float:
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"""
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How old our copy of this data is, in seconds
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"""
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if self.local:
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return 0
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if self.fetched is None:
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return 10000000000
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return (timezone.now() - self.fetched).total_seconds()
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def generate_keypair(self):
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if not self.local:
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raise ValueError("Cannot generate keypair for remote user")
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private_key = rsa.generate_private_key(
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public_exponent=65537,
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key_size=2048,
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)
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self.private_key = private_key.private_bytes(
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encoding=serialization.Encoding.PEM,
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format=serialization.PrivateFormat.PKCS8,
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encryption_algorithm=serialization.NoEncryption(),
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)
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self.public_key = private_key.public_key().public_bytes(
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encoding=serialization.Encoding.PEM,
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format=serialization.PublicFormat.SubjectPublicKeyInfo,
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)
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self.save()
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@classmethod
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async def fetch_webfinger(cls, handle: str) -> Tuple[Optional[str], Optional[str]]:
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"""
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Given a username@domain handle, returns a tuple of
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(actor uri, canonical handle) or None, None if it does not resolve.
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"""
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domain = handle.split("@")[1]
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async with httpx.AsyncClient() as client:
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response = await client.get(
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f"https://{domain}/.well-known/webfinger?resource=acct:{handle}",
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headers={"Accept": "application/json"},
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follow_redirects=True,
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)
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if response.status_code >= 400:
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return None, None
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data = response.json()
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if data["subject"].startswith("acct:"):
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data["subject"] = data["subject"][5:]
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for link in data["links"]:
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if (
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link.get("type") == "application/activity+json"
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and link.get("rel") == "self"
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):
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return link["href"], data["subject"]
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return None, None
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async def fetch_actor(self) -> bool:
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"""
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Fetches the user's actor information, as well as their domain from
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webfinger if it's available.
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"""
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if self.local:
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raise ValueError("Cannot fetch local identities")
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async with httpx.AsyncClient() as client:
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response = await client.get(
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self.actor_uri,
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headers={"Accept": "application/json"},
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follow_redirects=True,
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)
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if response.status_code >= 400:
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return False
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document = canonicalise(response.json(), include_security=True)
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self.name = document.get("name")
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self.profile_uri = document.get("url")
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self.inbox_uri = document.get("inbox")
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self.outbox_uri = document.get("outbox")
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self.summary = document.get("summary")
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self.username = document.get("preferredUsername")
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self.manually_approves_followers = document.get(
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"as:manuallyApprovesFollowers"
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)
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self.public_key = document.get("publicKey", {}).get("publicKeyPem")
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self.icon_uri = document.get("icon", {}).get("url")
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self.image_uri = document.get("image", {}).get("url")
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# Now go do webfinger with that info to see if we can get a canonical domain
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actor_url_parts = urlparse(self.actor_uri)
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get_domain = sync_to_async(Domain.get_remote_domain)
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if self.username:
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webfinger_actor, webfinger_handle = await self.fetch_webfinger(
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f"{self.username}@{actor_url_parts.hostname}"
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)
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if webfinger_handle:
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webfinger_username, webfinger_domain = webfinger_handle.split("@")
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self.username = webfinger_username
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self.domain = await get_domain(webfinger_domain)
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else:
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self.domain = await get_domain(actor_url_parts.hostname)
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else:
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self.domain = await get_domain(actor_url_parts.hostname)
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self.fetched = timezone.now()
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await sync_to_async(self.save)()
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return True
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def sign(self, cleartext: str) -> str:
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if not self.private_key:
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raise ValueError("Cannot sign - no private key")
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private_key = serialization.load_pem_private_key(
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self.private_key.encode("ascii"),
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password=None,
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)
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return base64.b64encode(
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private_key.sign(
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cleartext.encode("ascii"),
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padding.PSS(
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mgf=padding.MGF1(hashes.SHA256()),
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salt_length=padding.PSS.MAX_LENGTH,
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),
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hashes.SHA256(),
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)
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).decode("ascii")
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def verify_signature(self, signature: bytes, cleartext: str) -> bool:
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if not self.public_key:
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raise ValueError("Cannot verify - no public key")
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x509 = crypto.X509()
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x509.set_pubkey(
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crypto.load_publickey(
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crypto.FILETYPE_PEM,
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self.public_key.encode("ascii"),
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)
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)
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try:
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crypto.verify(x509, signature, cleartext.encode("ascii"), "sha256")
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except crypto.Error:
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return False
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return True
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async def signed_request(self, host, method, path, document):
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"""
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Delivers the document to the specified host, method, path and signed
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as this user.
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"""
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date_string = http_date(timezone.now().timestamp())
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headers = {
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"(request-target)": f"{method} {path}",
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"Host": host,
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"Date": date_string,
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}
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headers_string = " ".join(headers.keys())
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signed_string = "\n".join(f"{name}: {value}" for name, value in headers.items())
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signature = self.sign(signed_string)
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del headers["(request-target)"]
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headers[
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"Signature"
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] = f'keyId="{self.urls.key.full()}",headers="{headers_string}",signature="{signature}"'
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async with httpx.AsyncClient() as client:
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return await client.request(
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method,
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"https://{host}{path}",
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headers=headers,
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data=document,
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)
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def validate_signature(self, request):
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"""
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Attempts to validate the signature on an incoming request.
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Returns False if the signature is invalid, None if it cannot be verified
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as we do not have the key locally, or the name of the actor if it is valid.
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"""
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pass
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def __str__(self):
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return self.handle or self.actor_uri
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class urls(urlman.Urls):
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view = "/@{self.username}@{self.domain_id}/"
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view_short = "/@{self.username}/"
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actor = "{view}actor/"
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key = "{actor}#main-key"
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inbox = "{actor}inbox/"
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outbox = "{actor}outbox/"
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activate = "{view}activate/"
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def get_scheme(self, url):
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return "https"
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def get_hostname(self, url):
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return self.instance.domain.uri_domain
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