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import binascii
import sys
import traceback
import urllib.parse
from base64 import b64decode, b64encode
from collections.abc import Callable
from functools import wraps
from typing import Any, Optional
from wsgiref.util import application_uri, request_uri
from . import db
from .store import Auth, Store
from .types import (
App,
Closable,
Env,
Middleware,
ProtoMiddleware,
Response,
StartResponse,
)
DB_PATH = "paste.sqlite3"
def simple_response(
start_response: StartResponse,
status: str,
extra_headers: list[tuple[str, str]] = list(),
exc_info: Optional[tuple[Any, Any, Any]] = None,
) -> Response:
body = (status + "\n").encode()
start_response(
status,
[
("Content-Type", "text/plain"),
("Content-Length", str(len(body))),
*extra_headers,
],
exc_info,
)
return [body]
def middleware(f: ProtoMiddleware) -> Middleware:
@wraps(f)
def outer(app: App):
@wraps(app)
def inner(environ: Env, start_response: StartResponse):
return f(app, environ, start_response)
return inner
return outer
@middleware
def catch_exceptions(app: App, environ: Env, start_response: StartResponse) -> Response:
try:
return app(environ, start_response)
except Exception as e:
print("".join(traceback.format_exception(type(e), e, e.__traceback__)))
return simple_response(
start_response, "500 Internal Server Error", exc_info=sys.exc_info()
)
@middleware
def validate_method(app: App, environ: Env, start_response: StartResponse) -> Response:
if environ["REQUEST_METHOD"] in {"GET", "HEAD", "POST", "PUT", "DELETE", "OPTIONS"}:
return app(environ, start_response)
if environ["REQUEST_METHOD"] in {"CONNECT", "TRACE", "PATCH"}:
return simple_response(start_response, "405 Method Not Allowed")
return simple_response(start_response, "501 Not Implemented")
@middleware
def if_none_match(app: App, environ: Env, start_response: StartResponse) -> Response:
if "HTTP_IF_NONE_MATCH" not in environ:
return app(environ, start_response)
if_none_match = environ["HTTP_IF_NONE_MATCH"]
del environ["HTTP_IF_NONE_MATCH"]
if environ["REQUEST_METHOD"] not in {"GET", "HEAD"}:
return app(environ, start_response)
head_env = environ.copy()
head_env["REQUEST_METHOD"] = "HEAD"
etag = None
def head_start_response(
status: str,
headers: list[tuple[str, str]],
exc_info: Optional[tuple[Any, Any, Any]] = None,
) -> Callable[[bytes], object]:
_, _ = status, exc_info
nonlocal etag
for key, value in headers:
if key == "ETag":
etag = value[1:-1]
return lambda _: None
resp = app(head_env, head_start_response)
if isinstance(resp, Closable):
resp.close()
if not isinstance(etag, str):
return app(environ, start_response)
if if_none_match == "*":
start_response("304 Not Modified", [("ETag", f'"{etag}"')])
return []
etags = if_none_match.split(",")
etags = {e.strip(" \t").removeprefix("W/") for e in etags}
for e in etags:
if e[0] != '"' or e[-1] != '"':
return simple_response(start_response, "400 Bad Request")
etags = {e[1:-1] for e in etags}
if isinstance(etag, str) and etag in etags:
start_response("304 Not Modified", [("ETag", f'"{etag}"')])
return []
return app(environ, start_response)
@middleware
def options(app: App, environ: Env, start_response: StartResponse) -> Response:
if environ["REQUEST_METHOD"] != "OPTIONS":
return app(environ, start_response)
start_response(
"204 No Content",
[
("Allow", "GET, HEAD, POST, PUT, DELETE, OPTIONS"),
],
)
return []
@middleware
def open_database(app: App, environ: Env, start_response: StartResponse) -> Response:
db_path = environ.get("PASTE_DB", DB_PATH)
with db.connect(db_path) as conn:
environ["paste.db_conn"] = conn
return app(environ, start_response)
def authenticate(get_auth: Callable[[Env], Auth]) -> Middleware:
@middleware
def authenticate(app: App, environ: Env, start_response: StartResponse) -> Response:
def check_auth():
value = environ.get("HTTP_AUTHORIZATION")
if not isinstance(value, str):
return False
if not value.startswith("APIKey "):
return False
value = value.removeprefix("APIKey ")
try:
value = b64decode(value.encode(), validate=True)
except (binascii.Error, UnicodeEncodeError):
return False
return get_auth(environ).check_token(value)
if environ["REQUEST_METHOD"] in {"GET", "HEAD"} or check_auth():
return app(environ, start_response)
return simple_response(
start_response,
"401 Unauthorized",
extra_headers=[("WWW-Authenticate", "APIKey")],
)
return authenticate
def paste_application(
environ: Env,
start_response: StartResponse,
get_store: Callable[[Env], Store] = lambda environ: Store(environ["paste.db_conn"]),
/,
) -> Response:
store = get_store(environ)
name = environ["PATH_INFO"]
if environ["REQUEST_METHOD"] == "GET":
row = store.get(name)
if not row:
return simple_response(start_response, "404 Not Found")
content_type, content_hash, content = row
start_response(
"200 OK",
[
("Content-Type", content_type),
("Content-Length", str(len(content))),
("ETag", f'"{b64encode(content_hash).decode()}"'),
],
)
return [content]
elif environ["REQUEST_METHOD"] == "HEAD":
row = store.head(name)
if not row:
return simple_response(start_response, "404 Not Found")
content_type, content_hash, content_length = row
start_response(
"200 OK",
[
("Content-Type", content_type),
("Content-Length", str(content_length)),
("ETag", f'"{b64encode(content_hash).decode()}"'),
],
)
return []
elif environ["REQUEST_METHOD"] == "PUT":
content_type = environ.get("CONTENT_TYPE", "text/plain")
content_length = int(environ["CONTENT_LENGTH"])
content = environ["wsgi.input"].read(content_length)
created, content_hash = store.put(name, content, content_type)
start_response(
"201 Created" if created else "204 No Content",
[
("Location", request_uri(environ)),
("ETag", f'"{b64encode(content_hash).decode()}"'),
],
)
return []
elif environ["REQUEST_METHOD"] == "POST":
content_type = environ.get("CONTENT_TYPE", "text/plain")
content_length = int(environ["CONTENT_LENGTH"])
content = environ["wsgi.input"].read(content_length)
path, content_hash = store.post(name, content, content_type)
uri = application_uri(environ)
path = urllib.parse.quote(path)
if uri[-1] == "/" and path[:1] == "/":
uri += path[1:]
else:
uri += path
if environ.get("QUERY_STRING"):
uri += "?" + environ["QUERY_STRING"]
start_response(
"201 Created",
[("Location", uri), ("ETag", f'"{b64encode(content_hash).decode()}"')],
)
return []
elif environ["REQUEST_METHOD"] == "DELETE":
if store.delete(name):
start_response("204 No Content", [])
return []
return simple_response(start_response, "404 Not Found")
return simple_response(start_response, "500 Internal Server Error")
middlewares = [
catch_exceptions,
validate_method,
options,
if_none_match,
open_database,
authenticate(lambda environ: Auth(environ["paste.db_conn"])),
]
application: App = paste_application
for m in reversed(middlewares):
application = m(application)
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