Source code for h11._util

import sys
import re

__all__ = ["ProtocolError", "LocalProtocolError", "RemoteProtocolError",
           "validate", "make_sentinel", "bytesify"]

[docs]class ProtocolError(Exception): """Exception indicating a violation of the HTTP/1.1 protocol. This as an abstract base class, with two concrete base classes: :exc:`LocalProtocolError`, which indicates that you tried to do something that HTTP/1.1 says is illegal, and :exc:`RemoteProtocolError`, which indicates that the remote peer tried to do something that HTTP/1.1 says is illegal. See :ref:`error-handling` for details. In addition to the normal :exc:`Exception` features, it has one attribute: .. attribute:: error_status_hint This gives a suggestion as to what status code a server might use if this error occurred as part of a request. For a :exc:`RemoteProtocolError`, this is useful as a suggestion for how you might want to respond to a misbehaving peer, if you're implementing a server. For a :exc:`LocalProtocolError`, this can be taken as a suggestion for how your peer might have responded to *you* if h11 had allowed you to continue. The default is 400 Bad Request, a generic catch-all for protocol violations. """ def __init__(self, msg, error_status_hint=400): if type(self) is ProtocolError: raise TypeError("tried to directly instantiate ProtocolError") Exception.__init__(self, msg)
self.error_status_hint = error_status_hint # Strategy: there are a number of public APIs where a LocalProtocolError can # be raised (send(), all the different event constructors, ...), and only one # public API where RemoteProtocolError can be raised # (receive_data()). Therefore we always raise LocalProtocolError internally, # and then receive_data will translate this into a RemoteProtocolError. # # Internally: # LocalProtocolError is the generic "ProtocolError". # Externally: # LocalProtocolError is for local errors and RemoteProtocolError is for # remote errors.
[docs]class LocalProtocolError(ProtocolError): def _reraise_as_remote_protocol_error(self): # After catching a LocalProtocolError, use this method to re-raise it # as a RemoteProtocolError. This method must be called from inside an # except: block. # # An easy way to get an equivalent RemoteProtocolError is just to # modify 'self' in place. self.__class__ = RemoteProtocolError # But the re-raising is somewhat non-trivial -- you might think that # now that we've modified the in-flight exception object, that just # doing 'raise' to re-raise it would be enough. But it turns out that # this doesn't work, because Python tracks the exception type # (exc_info[0]) separately from the exception object (exc_info[1]), # and we only modified the latter. So we really do need to re-raise # the new type explicitly. if sys.version_info[0] >= 3: # On py3, the traceback is part of the exception object, so our # in-place modification preserved it and we can just re-raise: raise self else: # On py2, preserving the traceback requires 3-argument # raise... but on py3 this is a syntax error, so we have to hide # it inside an exec
exec("raise RemoteProtocolError, self, sys.exc_info()[2]")
[docs]class RemoteProtocolError(ProtocolError):
pass try: _fullmatch = type(re.compile('')).fullmatch except AttributeError: def _fullmatch(regex, data): # version specific: Python < 3.4 match = regex.match(data) if match and match.end() != len(data): match = None return match def validate(regex, data, msg="malformed data", *format_args): match = _fullmatch(regex, data) if not match: if format_args: msg = msg.format(*format_args) raise LocalProtocolError(msg) return match.groupdict() # Sentinel values # # - Inherit identity-based comparison and hashing from object # - Have a nice repr # - Have a *bonus property*: type(sentinel) is sentinel # # The bonus property is useful if you want to take the return value from # next_event() and do some sort of dispatch based on type(event). class _SentinelBase(type): def __repr__(self): return self.__name__ def make_sentinel(name): cls = _SentinelBase(name, (_SentinelBase,), {}) cls.__class__ = cls return cls # Used for methods, request targets, HTTP versions, header names, and header # values. Accepts ascii-strings, or bytes/bytearray/memoryview/..., and always # returns bytes. def bytesify(s): # Fast-path: if type(s) is bytes: return s if isinstance(s, str): s = s.encode("ascii") if isinstance(s, int): raise TypeError("expected bytes-like object, not int") return bytes(s)