_!@sddlZddlmZddlmZddlmZddlmZddlm Z ddl m Z d d Z Gd d d e ZdS) N) text_type)json) want_bytes) BadPayload) BadSignature)SignercCst|jitS)z5Checks whether a serializer generates text or binary.) isinstancedumpsr) serializerr ?/tmp/pip-build-5gj8f0j9/itsdangerous/itsdangerous/serializer.pyis_text_serializer src@seZdZdZeZeZdej igZ ddddddddZ dddZ d d Z dd d Zdd dZdddZdddZdddZdddZdddZddddZddZdS) SerializeraThis class provides a serialization interface on top of the signer. It provides a similar API to json/pickle and other modules but is structured differently internally. If you want to change the underlying implementation for parsing and loading you have to override the :meth:`load_payload` and :meth:`dump_payload` functions. This implementation uses simplejson if available for dumping and loading and will fall back to the standard library's json module if it's not available. You do not need to subclass this class in order to switch out or customize the :class:`.Signer`. You can instead pass a different class to the constructor as well as keyword arguments as a dict that should be forwarded. .. code-block:: python s = Serializer(signer_kwargs={'key_derivation': 'hmac'}) You may want to upgrade the signing parameters without invalidating existing signatures that are in use. Fallback signatures can be given that will be tried if unsigning with the current signer fails. Fallback signers can be defined by providing a list of ``fallback_signers``. Each item can be one of the following: a signer class (which is instantiated with ``signer_kwargs``, ``salt``, and ``secret_key``), a tuple ``(signer_class, signer_kwargs)``, or a dict of ``signer_kwargs``. For example, this is a serializer that signs using SHA-512, but will unsign using either SHA-512 or SHA1: .. code-block:: python s = Serializer( signer_kwargs={"digest_method": hashlib.sha512}, fallback_signers=[{"digest_method": hashlib.sha1}] ) .. versionchanged:: 0.14: The ``signer`` and ``signer_kwargs`` parameters were added to the constructor. .. versionchanged:: 1.1.0: Added support for ``fallback_signers`` and configured a default SHA-512 fallback. This fallback is for users who used the yanked 1.0.0 release which defaulted to SHA-512. Z digest_methods itsdangerousNcCst||_t||_|dkr3|j}||_t||_|dkr`|j}||_|pri|_|dkrt |j pf}||_ |pi|_ dS)N) r secret_keysaltdefault_serializerr rdefault_signersigner signer_kwargslistdefault_fallback_signersfallback_signersserializer_kwargs)selfrrr rrrrr r r __init__Ps         zSerializer.__init__cCs|dkr!|j}|j}n t|}y&|rE|jd}|j|SWn7tk r}ztdd|WYdd}~XnXdS)aLoads the encoded object. This function raises :class:`.BadPayload` if the payload is not valid. The ``serializer`` parameter can be used to override the serializer stored on the class. The encoded ``payload`` should always be bytes. Nzutf-8zSCould not load the payload because an exception occurred on unserializing the data.original_error)r rdecodeloads Exceptionr)rpayloadr Zis_texter r r load_payloadis    zSerializer.load_payloadcCst|jj||jS)zDumps the encoded object. The return value is always bytes. If the internal serializer returns text, the value will be encoded as UTF-8. )rr r r)robjr r r dump_payloadszSerializer.dump_payloadcCs1|dkr|j}|j|jd||jS)zCreates a new instance of the signer to be used. The default implementation uses the :class:`.Signer` base class. Nr)rrrr)rrr r r make_signers  zSerializer.make_signerccs|dkr|j}|j|Vxv|jD]k}t|tkrW|}|j}n*t|tkrx|\}}n |j}||jd||Vq-WdS)zIterates over all signers to be tried for unsigning. Starts with the configured signer, then constructs each signer specified in ``fallback_signers``. Nr) rr%rtypedictrtuplerr)rrfallbackkwargsr r r iter_unsignerss    zSerializer.iter_unsignerscCsIt|j|}|j|j|}|jrE|jd}|S)zReturns a signed string serialized with the internal serializer. The return value can be either a byte or unicode string depending on the format of the internal serializer. zutf-8)rr$r%signrr)rr#rr rvr r r r s  zSerializer.dumpscCs|j|j||dS)zLike :meth:`dumps` but dumps into a file. The file handle has to be compatible with what the internal serializer expects. N)writer )rr#frr r r dumpszSerializer.dumpcCs~t|}d}x_|j|D]N}y|j|j|SWq"tk ro}z |}WYdd}~Xq"Xq"W|dS)ziReverse of :meth:`dumps`. Raises :exc:`.BadSignature` if the signature validation fails. N)rr+r"Zunsignr)rsrZlast_exceptionrerrr r r rs zSerializer.loadscCs|j|j|S)z)Like :meth:`loads` but loads from a file.)rread)rr/rr r r loadszSerializer.loadcCs|j||S)a9Like :meth:`loads` but without verifying the signature. This is potentially very dangerous to use depending on how your serializer works. The return value is ``(signature_valid, payload)`` instead of just the payload. The first item will be a boolean that indicates if the signature is valid. This function never fails. Use it for debugging only and if you know that your serializer module is not exploitable (for example, do not use it with a pickle serializer). .. versionadded:: 0.15 )_loads_unsafe_impl)rr1rr r r loads_unsafeszSerializer.loads_unsafecCsy&d|j|d||pifSWnttk r}zT|jdkrNdSy#d|j|j|piifSWntk rdSYnXWYdd}~XnXdS)zfLow level helper function to implement :meth:`loads_unsafe` in serializer subclasses. TrNF)FN)FN)rrr r"r)rr1rZ load_kwargsZload_payload_kwargsr!r r r r5s&  zSerializer._loads_unsafe_implcOs|j|j||S)zYLike :meth:`loads_unsafe` but loads from a file. .. versionadded:: 0.15 )r6r3)rr/argsr*r r r load_unsafeszSerializer.load_unsafe)__name__ __module__ __qualname____doc__rrrrhashlibsha512rrr"r$r%r+r r0rr4r6r5r8r r r r rs* 1   r)r=_compatr_jsonrencodingrexcrrrrrobjectrr r r r s