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87 lines
2.5 KiB
Python
87 lines
2.5 KiB
Python
import re
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import secrets
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from typing import Any, Dict, Mapping, Optional
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import orjson
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import redis
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from django.conf import settings
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# Redis accepts keys up to 512MB in size, but there's no reason for us to use such size,
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# so we want to stay limited to 1024 characters.
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MAX_KEY_LENGTH = 1024
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class ZulipRedisError(Exception):
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pass
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class ZulipRedisKeyTooLongError(ZulipRedisError):
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pass
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class ZulipRedisKeyOfWrongFormatError(ZulipRedisError):
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pass
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def get_redis_client() -> "redis.StrictRedis[bytes]":
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return redis.StrictRedis(
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host=settings.REDIS_HOST,
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port=settings.REDIS_PORT,
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password=settings.REDIS_PASSWORD,
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db=0,
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decode_responses=False,
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)
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def put_dict_in_redis(
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redis_client: "redis.StrictRedis[bytes]",
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key_format: str,
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data_to_store: Mapping[str, Any],
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expiration_seconds: int,
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token_length: int = 64,
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token: Optional[str] = None,
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) -> str:
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key_length = len(key_format) - len("{token}") + token_length
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if key_length > MAX_KEY_LENGTH:
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raise ZulipRedisKeyTooLongError(
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f"Requested key too long in put_dict_in_redis. Key format: {key_format}, token length: {token_length}",
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)
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if token is None:
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token = secrets.token_hex(token_length // 2)
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key = key_format.format(token=token)
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with redis_client.pipeline() as pipeline:
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pipeline.set(key, orjson.dumps(data_to_store))
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pipeline.expire(key, expiration_seconds)
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pipeline.execute()
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return key
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def get_dict_from_redis(
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redis_client: "redis.StrictRedis[bytes]",
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key_format: str,
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key: str,
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) -> Optional[Dict[str, Any]]:
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# This function requires inputting the intended key_format to validate
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# that the key fits it, as an additionally security measure. This protects
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# against bugs where a caller requests a key based on user input and doesn't
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# validate it - which could potentially allow users to poke around arbitrary Redis keys.
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if len(key) > MAX_KEY_LENGTH:
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raise ZulipRedisKeyTooLongError(
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f"Requested key too long in get_dict_from_redis: {key}",
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)
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validate_key_fits_format(key, key_format)
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data = redis_client.get(key)
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if data is None:
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return None
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return orjson.loads(data)
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def validate_key_fits_format(key: str, key_format: str) -> None:
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assert "{token}" in key_format
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regex = key_format.format(token=r"[a-zA-Z0-9]+")
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if not re.fullmatch(regex, key):
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raise ZulipRedisKeyOfWrongFormatError(f"{key} does not match format {key_format}")
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