shell bypass 403
__all__ = ['BaseResolver', 'Resolver']
from .error import *
from .nodes import *
import re
class ResolverError(YAMLError):
pass
class BaseResolver:
DEFAULT_SCALAR_TAG = 'tag:yaml.org,2002:str'
DEFAULT_SEQUENCE_TAG = 'tag:yaml.org,2002:seq'
DEFAULT_MAPPING_TAG = 'tag:yaml.org,2002:map'
yaml_implicit_resolvers = {}
yaml_path_resolvers = {}
def __init__(self):
self.resolver_exact_paths = []
self.resolver_prefix_paths = []
@classmethod
def add_implicit_resolver(cls, tag, regexp, first):
if not 'yaml_implicit_resolvers' in cls.__dict__:
implicit_resolvers = {}
for key in cls.yaml_implicit_resolvers:
implicit_resolvers[key] = cls.yaml_implicit_resolvers[key][:]
cls.yaml_implicit_resolvers = implicit_resolvers
if first is None:
first = [None]
for ch in first:
cls.yaml_implicit_resolvers.setdefault(ch, []).append((tag, regexp))
@classmethod
def add_path_resolver(cls, tag, path, kind=None):
# Note: `add_path_resolver` is experimental. The API could be changed.
# `new_path` is a pattern that is matched against the path from the
# root to the node that is being considered. `node_path` elements are
# tuples `(node_check, index_check)`. `node_check` is a node class:
# `ScalarNode`, `SequenceNode`, `MappingNode` or `None`. `None`
# matches any kind of a node. `index_check` could be `None`, a boolean
# value, a string value, or a number. `None` and `False` match against
# any _value_ of sequence and mapping nodes. `True` matches against
# any _key_ of a mapping node. A string `index_check` matches against
# a mapping value that corresponds to a scalar key which content is
# equal to the `index_check` value. An integer `index_check` matches
# against a sequence value with the index equal to `index_check`.
if not 'yaml_path_resolvers' in cls.__dict__:
cls.yaml_path_resolvers = cls.yaml_path_resolvers.copy()
new_path = []
for element in path:
if isinstance(element, (list, tuple)):
if len(element) == 2:
node_check, index_check = element
elif len(element) == 1:
node_check = element[0]
index_check = True
else:
raise ResolverError("Invalid path element: %s" % element)
else:
node_check = None
index_check = element
if node_check is str:
node_check = ScalarNode
elif node_check is list:
node_check = SequenceNode
elif node_check is dict:
node_check = MappingNode
elif node_check not in [ScalarNode, SequenceNode, MappingNode] \
and not isinstance(node_check, str) \
and node_check is not None:
raise ResolverError("Invalid node checker: %s" % node_check)
if not isinstance(index_check, (str, int)) \
and index_check is not None:
raise ResolverError("Invalid index checker: %s" % index_check)
new_path.append((node_check, index_check))
if kind is str:
kind = ScalarNode
elif kind is list:
kind = SequenceNode
elif kind is dict:
kind = MappingNode
elif kind not in [ScalarNode, SequenceNode, MappingNode] \
and kind is not None:
raise ResolverError("Invalid node kind: %s" % kind)
cls.yaml_path_resolvers[tuple(new_path), kind] = tag
def descend_resolver(self, current_node, current_index):
if not self.yaml_path_resolvers:
return
exact_paths = {}
prefix_paths = []
if current_node:
depth = len(self.resolver_prefix_paths)
for path, kind in self.resolver_prefix_paths[-1]:
if self.check_resolver_prefix(depth, path, kind,
current_node, current_index):
if len(path) > depth:
prefix_paths.append((path, kind))
else:
exact_paths[kind] = self.yaml_path_resolvers[path, kind]
else:
for path, kind in self.yaml_path_resolvers:
if not path:
exact_paths[kind] = self.yaml_path_resolvers[path, kind]
else:
prefix_paths.append((path, kind))
self.resolver_exact_paths.append(exact_paths)
self.resolver_prefix_paths.append(prefix_paths)
def ascend_resolver(self):
if not self.yaml_path_resolvers:
return
self.resolver_exact_paths.pop()
self.resolver_prefix_paths.pop()
def check_resolver_prefix(self, depth, path, kind,
current_node, current_index):
node_check, index_check = path[depth-1]
if isinstance(node_check, str):
if current_node.tag != node_check:
return
elif node_check is not None:
if not isinstance(current_node, node_check):
return
if index_check is True and current_index is not None:
return
if (index_check is False or index_check is None) \
and current_index is None:
return
if isinstance(index_check, str):
if not (isinstance(current_index, ScalarNode)
and index_check == current_index.value):
return
elif isinstance(index_check, int) and not isinstance(index_check, bool):
if index_check != current_index:
return
return True
def resolve(self, kind, value, implicit):
if kind is ScalarNode and implicit[0]:
if value == '':
resolvers = self.yaml_implicit_resolvers.get('', [])
else:
resolvers = self.yaml_implicit_resolvers.get(value[0], [])
wildcard_resolvers = self.yaml_implicit_resolvers.get(None, [])
for tag, regexp in resolvers + wildcard_resolvers:
if regexp.match(value):
return tag
implicit = implicit[1]
if self.yaml_path_resolvers:
exact_paths = self.resolver_exact_paths[-1]
if kind in exact_paths:
return exact_paths[kind]
if None in exact_paths:
return exact_paths[None]
if kind is ScalarNode:
return self.DEFAULT_SCALAR_TAG
elif kind is SequenceNode:
return self.DEFAULT_SEQUENCE_TAG
elif kind is MappingNode:
return self.DEFAULT_MAPPING_TAG
class Resolver(BaseResolver):
pass
Resolver.add_implicit_resolver(
'tag:yaml.org,2002:bool',
re.compile(r'''^(?:yes|Yes|YES|no|No|NO
|true|True|TRUE|false|False|FALSE
|on|On|ON|off|Off|OFF)$''', re.X),
list('yYnNtTfFoO'))
Resolver.add_implicit_resolver(
'tag:yaml.org,2002:float',
re.compile(r'''^(?:[-+]?(?:[0-9][0-9_]*)\.[0-9_]*(?:[eE][-+][0-9]+)?
|\.[0-9_]+(?:[eE][-+][0-9]+)?
|[-+]?[0-9][0-9_]*(?::[0-5]?[0-9])+\.[0-9_]*
|[-+]?\.(?:inf|Inf|INF)
|\.(?:nan|NaN|NAN))$''', re.X),
list('-+0123456789.'))
Resolver.add_implicit_resolver(
'tag:yaml.org,2002:int',
re.compile(r'''^(?:[-+]?0b[0-1_]+
|[-+]?0[0-7_]+
|[-+]?(?:0|[1-9][0-9_]*)
|[-+]?0x[0-9a-fA-F_]+
|[-+]?[1-9][0-9_]*(?::[0-5]?[0-9])+)$''', re.X),
list('-+0123456789'))
Resolver.add_implicit_resolver(
'tag:yaml.org,2002:merge',
re.compile(r'^(?:<<)$'),
['<'])
Resolver.add_implicit_resolver(
'tag:yaml.org,2002:null',
re.compile(r'''^(?: ~
|null|Null|NULL
| )$''', re.X),
['~', 'n', 'N', ''])
Resolver.add_implicit_resolver(
'tag:yaml.org,2002:timestamp',
re.compile(r'''^(?:[0-9][0-9][0-9][0-9]-[0-9][0-9]-[0-9][0-9]
|[0-9][0-9][0-9][0-9] -[0-9][0-9]? -[0-9][0-9]?
(?:[Tt]|[ \t]+)[0-9][0-9]?
:[0-9][0-9] :[0-9][0-9] (?:\.[0-9]*)?
(?:[ \t]*(?:Z|[-+][0-9][0-9]?(?::[0-9][0-9])?))?)$''', re.X),
list('0123456789'))
Resolver.add_implicit_resolver(
'tag:yaml.org,2002:value',
re.compile(r'^(?:=)$'),
['='])
# The following resolver is only for documentation purposes. It cannot work
# because plain scalars cannot start with '!', '&', or '*'.
Resolver.add_implicit_resolver(
'tag:yaml.org,2002:yaml',
re.compile(r'^(?:!|&|\*)$'),
list('!&*'))