forked from mia/0x0
Emi Simpson
af4b3b06c0
SUPPLEMENTALLY: - Add an `expiration` field to the `file` table of the database - Produce a migration for the above change - Overhaul the cleanup script, and integrate into fhost.py (now run using FLASK_APP=fhost flask prune) - Replace the old cleanup script with a deprecation notice - Add information about how to expire files to the index - Update the README with information about the new script Squashed commits: Add a note explaining that expired files aren't immediately removed Show correct times on the index page graph Improve the migration script, removing the need for --legacy Use automap in place of an explicit file map in migration Remove vestigial `touch()` Don't crash when upgrading a fresh database Remove vestigial warning about legacy files More efficiently filter to unexpired files when migrating mia/0x0#72 (comment) Coalesce updates to the database during migration mia/0x0#72 (comment) Remove vestigial database model mia/0x0#72 (comment) prune: Stream expired files from the database (as opposed to collecting them all first) config.example.py: Add min & max expiration + description
511 lines
16 KiB
Python
Executable file
511 lines
16 KiB
Python
Executable file
#!/usr/bin/env python3
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# -*- coding: utf-8 -*-
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"""
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Copyright © 2020 Mia Herkt
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Licensed under the EUPL, Version 1.2 or - as soon as approved
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by the European Commission - subsequent versions of the EUPL
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(the "License");
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You may not use this work except in compliance with the License.
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You may obtain a copy of the license at:
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https://joinup.ec.europa.eu/software/page/eupl
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Unless required by applicable law or agreed to in writing,
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software distributed under the License is distributed on an
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"AS IS" basis, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
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either express or implied.
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See the License for the specific language governing permissions
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and limitations under the License.
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"""
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from flask import Flask, abort, make_response, redirect, request, send_from_directory, url_for, Response, render_template
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from flask_sqlalchemy import SQLAlchemy
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from flask_migrate import Migrate
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from sqlalchemy import and_
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from jinja2.exceptions import *
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from jinja2 import ChoiceLoader, FileSystemLoader
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from hashlib import sha256
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from magic import Magic
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from mimetypes import guess_extension
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import click
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import os
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import sys
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import time
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import typing
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import requests
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from validators import url as url_valid
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from pathlib import Path
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app = Flask(__name__, instance_relative_config=True)
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app.config.update(
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SQLALCHEMY_TRACK_MODIFICATIONS = False,
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PREFERRED_URL_SCHEME = "https", # nginx users: make sure to have 'uwsgi_param UWSGI_SCHEME $scheme;' in your config
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MAX_CONTENT_LENGTH = 256 * 1024 * 1024,
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MAX_URL_LENGTH = 4096,
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USE_X_SENDFILE = False,
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FHOST_USE_X_ACCEL_REDIRECT = True, # expect nginx by default
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FHOST_STORAGE_PATH = "up",
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FHOST_MAX_EXT_LENGTH = 9,
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FHOST_EXT_OVERRIDE = {
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"audio/flac" : ".flac",
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"image/gif" : ".gif",
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"image/jpeg" : ".jpg",
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"image/png" : ".png",
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"image/svg+xml" : ".svg",
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"video/webm" : ".webm",
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"video/x-matroska" : ".mkv",
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"application/octet-stream" : ".bin",
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"text/plain" : ".log",
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"text/plain" : ".txt",
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"text/x-diff" : ".diff",
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},
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FHOST_MIME_BLACKLIST = [
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"application/x-dosexec",
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"application/java-archive",
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"application/java-vm"
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],
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FHOST_UPLOAD_BLACKLIST = None,
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NSFW_DETECT = False,
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NSFW_THRESHOLD = 0.608,
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URL_ALPHABET = "DEQhd2uFteibPwq0SWBInTpA_jcZL5GKz3YCR14Ulk87Jors9vNHgfaOmMXy6Vx-",
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)
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if not app.config["TESTING"]:
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app.config.from_pyfile("config.py")
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app.jinja_loader = ChoiceLoader([
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FileSystemLoader(str(Path(app.instance_path) / "templates")),
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app.jinja_loader
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])
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if app.config["DEBUG"]:
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app.config["FHOST_USE_X_ACCEL_REDIRECT"] = False
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if app.config["NSFW_DETECT"]:
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from nsfw_detect import NSFWDetector
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nsfw = NSFWDetector()
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try:
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mimedetect = Magic(mime=True, mime_encoding=False)
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except:
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print("""Error: You have installed the wrong version of the 'magic' module.
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Please install python-magic.""")
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sys.exit(1)
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db = SQLAlchemy(app)
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migrate = Migrate(app, db)
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class URL(db.Model):
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id = db.Column(db.Integer, primary_key = True)
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url = db.Column(db.UnicodeText, unique = True)
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def __init__(self, url):
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self.url = url
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def getname(self):
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return su.enbase(self.id)
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def geturl(self):
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return url_for("get", path=self.getname(), _external=True) + "\n"
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def get(url):
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u = URL.query.filter_by(url=url).first()
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if not u:
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u = URL(url)
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db.session.add(u)
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db.session.commit()
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return u
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class File(db.Model):
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id = db.Column(db.Integer, primary_key = True)
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sha256 = db.Column(db.String, unique = True)
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ext = db.Column(db.UnicodeText)
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mime = db.Column(db.UnicodeText)
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addr = db.Column(db.UnicodeText)
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removed = db.Column(db.Boolean, default=False)
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nsfw_score = db.Column(db.Float)
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expiration = db.Column(db.BigInteger)
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def __init__(self, sha256, ext, mime, addr, expiration):
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self.sha256 = sha256
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self.ext = ext
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self.mime = mime
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self.addr = addr
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self.expiration = expiration
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def getname(self):
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return u"{0}{1}".format(su.enbase(self.id), self.ext)
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def geturl(self):
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n = self.getname()
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if self.nsfw_score and self.nsfw_score > app.config["NSFW_THRESHOLD"]:
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return url_for("get", path=n, _external=True, _anchor="nsfw") + "\n"
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else:
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return url_for("get", path=n, _external=True) + "\n"
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"""
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requested_expiration can be:
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- None, to use the longest allowed file lifespan
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- a duration (in hours) that the file should live for
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- a timestamp in epoch millis that the file should expire at
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Any value greater that the longest allowed file lifespan will be rounded down to that
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value.
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"""
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def store(file_, requested_expiration: typing.Optional[int], addr):
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data = file_.read()
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digest = sha256(data).hexdigest()
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def get_mime():
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guess = mimedetect.from_buffer(data)
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app.logger.debug(f"MIME - specified: '{file_.content_type}' - detected: '{guess}'")
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if not file_.content_type or not "/" in file_.content_type or file_.content_type == "application/octet-stream":
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mime = guess
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else:
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mime = file_.content_type
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if mime in app.config["FHOST_MIME_BLACKLIST"] or guess in app.config["FHOST_MIME_BLACKLIST"]:
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abort(415)
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if mime.startswith("text/") and not "charset" in mime:
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mime += "; charset=utf-8"
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return mime
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def get_ext(mime):
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ext = "".join(Path(file_.filename).suffixes[-2:])
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gmime = mime.split(";")[0]
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guess = guess_extension(gmime)
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app.logger.debug(f"extension - specified: '{ext}' - detected: '{guess}'")
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if not ext:
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if gmime in app.config["FHOST_EXT_OVERRIDE"]:
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ext = app.config["FHOST_EXT_OVERRIDE"][gmime]
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else:
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ext = guess_extension(gmime)
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return ext[:app.config["FHOST_MAX_EXT_LENGTH"]] or ".bin"
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# Returns the epoch millisecond that this file should expire
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#
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# Uses the expiration time provided by the user (requested_expiration)
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# upper-bounded by an algorithm that computes the size based on the size of the
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# file.
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#
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# That is, all files are assigned a computed expiration, which can voluntarily
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# shortened by the user either by providing a timestamp in epoch millis or a
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# duration in hours.
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def get_expiration() -> int:
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current_epoch_millis = time.time() * 1000;
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# Maximum lifetime of the file in milliseconds
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this_files_max_lifespan = get_max_lifespan(len(data));
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# The latest allowed expiration date for this file, in epoch millis
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this_files_max_expiration = this_files_max_lifespan + 1000 * time.time();
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if requested_expiration is None:
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return this_files_max_expiration
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elif requested_expiration < 1650460320000:
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# Treat the requested expiration time as a duration in hours
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requested_expiration_ms = requested_expiration * 60 * 60 * 1000
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return min(this_files_max_expiration, current_epoch_millis + requested_expiration_ms)
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else:
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# Treat the requested expiration time as a timestamp in epoch millis
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return min(this_files_max_expiration, requested_expiration);
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f = File.query.filter_by(sha256=digest).first()
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if f:
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# If the file already exists
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if f.removed:
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# The file was removed by moderation, so don't accept it back
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abort(451)
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if f.expiration is None:
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# The file has expired, so give it a new expiration date
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f.expiration = get_expiration()
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else:
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# The file already exists, update the expiration if needed
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f.expiration = max(f.expiration, get_expiration())
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else:
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mime = get_mime()
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ext = get_ext(mime)
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expiration = get_expiration()
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f = File(digest, ext, mime, addr, expiration)
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f.addr = addr
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storage = Path(app.config["FHOST_STORAGE_PATH"])
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storage.mkdir(parents=True, exist_ok=True)
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p = storage / digest
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if not p.is_file():
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with open(p, "wb") as of:
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of.write(data)
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if not f.nsfw_score and app.config["NSFW_DETECT"]:
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f.nsfw_score = nsfw.detect(p)
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db.session.add(f)
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db.session.commit()
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return f
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class UrlEncoder(object):
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def __init__(self,alphabet, min_length):
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self.alphabet = alphabet
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self.min_length = min_length
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def enbase(self, x):
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n = len(self.alphabet)
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str = ""
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while x > 0:
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str = (self.alphabet[int(x % n)]) + str
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x = int(x // n)
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padding = self.alphabet[0] * (self.min_length - len(str))
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return '%s%s' % (padding, str)
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def debase(self, x):
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n = len(self.alphabet)
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result = 0
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for i, c in enumerate(reversed(x)):
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result += self.alphabet.index(c) * (n ** i)
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return result
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su = UrlEncoder(alphabet=app.config["URL_ALPHABET"], min_length=1)
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def fhost_url(scheme=None):
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if not scheme:
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return url_for(".fhost", _external=True).rstrip("/")
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else:
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return url_for(".fhost", _external=True, _scheme=scheme).rstrip("/")
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def is_fhost_url(url):
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return url.startswith(fhost_url()) or url.startswith(fhost_url("https"))
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def shorten(url):
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if len(url) > app.config["MAX_URL_LENGTH"]:
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abort(414)
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if not url_valid(url) or is_fhost_url(url) or "\n" in url:
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abort(400)
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u = URL.get(url)
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return u.geturl()
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def in_upload_bl(addr):
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if app.config["FHOST_UPLOAD_BLACKLIST"]:
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with app.open_instance_resource(app.config["FHOST_UPLOAD_BLACKLIST"], "r") as bl:
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check = addr.lstrip("::ffff:")
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for l in bl.readlines():
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if not l.startswith("#"):
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if check == l.rstrip():
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return True
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return False
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"""
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requested_expiration can be:
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- None, to use the longest allowed file lifespan
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- a duration (in hours) that the file should live for
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- a timestamp in epoch millis that the file should expire at
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Any value greater that the longest allowed file lifespan will be rounded down to that
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value.
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"""
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def store_file(f, requested_expiration: typing.Optional[int], addr):
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if in_upload_bl(addr):
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return "Your host is blocked from uploading files.\n", 451
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sf = File.store(f, requested_expiration, addr)
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return sf.geturl()
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def store_url(url, addr):
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if is_fhost_url(url):
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abort(400)
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h = { "Accept-Encoding" : "identity" }
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r = requests.get(url, stream=True, verify=False, headers=h)
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try:
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r.raise_for_status()
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except requests.exceptions.HTTPError as e:
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return str(e) + "\n"
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if "content-length" in r.headers:
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l = int(r.headers["content-length"])
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if l < app.config["MAX_CONTENT_LENGTH"]:
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def urlfile(**kwargs):
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return type('',(),kwargs)()
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f = urlfile(read=r.raw.read, content_type=r.headers["content-type"], filename="")
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return store_file(f, None, addr)
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else:
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abort(413)
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else:
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abort(411)
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@app.route("/<path:path>")
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def get(path):
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path = Path(path.split("/", 1)[0])
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sufs = "".join(path.suffixes[-2:])
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name = path.name[:-len(sufs) or None]
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id = su.debase(name)
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if sufs:
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f = File.query.get(id)
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if f and f.ext == sufs:
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if f.removed:
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abort(451)
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fpath = Path(app.config["FHOST_STORAGE_PATH"]) / f.sha256
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if not fpath.is_file():
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abort(404)
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if app.config["FHOST_USE_X_ACCEL_REDIRECT"]:
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response = make_response()
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response.headers["Content-Type"] = f.mime
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response.headers["Content-Length"] = fpath.stat().st_size
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response.headers["X-Accel-Redirect"] = "/" + str(fpath)
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return response
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else:
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return send_from_directory(app.config["FHOST_STORAGE_PATH"], f.sha256, mimetype = f.mime)
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else:
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u = URL.query.get(id)
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if u:
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return redirect(u.url)
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abort(404)
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@app.route("/", methods=["GET", "POST"])
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def fhost():
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if request.method == "POST":
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sf = None
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if "file" in request.files:
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try:
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# Store the file with the requested expiration date
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return store_file(
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request.files["file"],
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int(request.form["expires"]),
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request.remote_addr
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)
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except ValueError:
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# The requested expiration date wasn't properly formed
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abort(400)
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except KeyError:
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# No expiration date was requested, store with the max lifespan
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return store_file(
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request.files["file"],
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None,
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request.remote_addr
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)
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elif "url" in request.form:
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return store_url(request.form["url"], request.remote_addr)
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elif "shorten" in request.form:
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return shorten(request.form["shorten"])
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abort(400)
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else:
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return render_template("index.html")
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@app.route("/robots.txt")
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def robots():
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return """User-agent: *
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Disallow: /
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"""
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@app.errorhandler(400)
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@app.errorhandler(404)
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@app.errorhandler(411)
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@app.errorhandler(413)
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@app.errorhandler(414)
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@app.errorhandler(415)
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@app.errorhandler(451)
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def ehandler(e):
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try:
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return render_template(f"{e.code}.html", id=id), e.code
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except TemplateNotFound:
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return "Segmentation fault\n", e.code
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@app.cli.command("prune")
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def prune():
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"""
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Clean up expired files
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Deletes any files from the filesystem which have hit their expiration time. This
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doesn't remove them from the database, only from the filesystem. It's recommended
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that server owners run this command regularly, or set it up on a timer.
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"""
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current_time = time.time() * 1000;
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# The path to where uploaded files are stored
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storage = Path(app.config["FHOST_STORAGE_PATH"])
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# A list of all files who've passed their expiration times
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expired_files = File.query\
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.where(
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and_(
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File.expiration.is_not(None),
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File.expiration < current_time
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)
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)
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files_removed = 0;
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# For every expired file...
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for file in expired_files:
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# Log the file we're about to remove
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file_name = file.getname()
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file_hash = file.sha256
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file_path = storage / file_hash
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print(f"Removing expired file {file_name} [{file_hash}]")
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# Remove it from the file system
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try:
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os.remove(file_path)
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files_removed += 1;
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except FileNotFoundError:
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pass # If the file was already gone, we're good
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except OSError as e:
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print(e)
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print(
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"\n------------------------------------"
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"Encountered an error while trying to remove file {file_path}. Double"
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"check to make sure the server is configured correctly, permissions are"
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"okay, and everything is ship shape, then try again.")
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return;
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# Finally, mark that the file was removed
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file.expiration = None;
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db.session.commit()
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print(f"\nDone! {files_removed} file(s) removed")
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""" For a file of a given size, determine the largest allowed lifespan of that file
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Based on the current app's configuration: Specifically, the MAX_CONTENT_LENGTH, as well
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as FHOST_{MIN,MAX}_EXPIRATION.
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This lifespan may be shortened by a user's request, but no files should be allowed to
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expire at a point after this number.
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Value returned is a duration in milliseconds.
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"""
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def get_max_lifespan(filesize: int) -> int:
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min_exp = app.config.get("FHOST_MIN_EXPIRATION", 30 * 24 * 60 * 60 * 1000)
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max_exp = app.config.get("FHOST_MAX_EXPIRATION", 365 * 24 * 60 * 60 * 1000)
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max_size = app.config.get("MAX_CONTENT_LENGTH", 256 * 1024 * 1024)
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return min_exp + int((-max_exp + min_exp) * (filesize / max_size - 1) ** 3)
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