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import io
import ecdsa
import hashlib
import yaml
import base64
import sys
def render_path(path):
if path:
return "'" + ", ".join(path) + "'"
else:
return "the top level"
class ErrorHandlingDict(dict):
def __init__(self, filename, path):
self._filename = filename
self._path = path
dict.__init__({})
def __missing__(self, key):
path = render_path(self._path)
print >>sys.stderr, "error: could not find configuration key '%s' at %s in %s" % (key, path, self._filename)
sys.exit(1)
def errorhandlify(term, filename, path=[]):
if isinstance(term, basestring):
return term
elif isinstance(term, int):
return term
elif isinstance(term, dict):
result = ErrorHandlingDict(filename, path)
for k, v in term.items():
result[k] = errorhandlify(v, filename, path + [k])
return result
elif isinstance(term, list):
return [errorhandlify(e, filename, path + ["item %d" % i]) for i, e in enumerate(term, start=1)]
else:
print "unknown type", type(term)
sys.exit(1)
def verify_config(rawconfig, signature, publickey_base64, filename):
publickey = base64.decodestring(publickey_base64)
try:
vk = ecdsa.VerifyingKey.from_der(publickey)
vk.verify(signature, rawconfig, hashfunc=hashlib.sha256,
sigdecode=ecdsa.util.sigdecode_der)
except ecdsa.keys.BadSignatureError:
print >>sys.stderr, "error: configuration file %s did not have a correct signature" % (filename,)
sys.exit(1)
return errorhandlify(yaml.load(io.BytesIO(rawconfig), yaml.SafeLoader), filename)
def verify_and_read_config(filename, publickey_base64, schema=None):
rawconfig = open(filename).read()
signature = open(filename + ".sig").read()
verify_config(rawconfig, signature, publickey_base64, filename)
config = yaml.load(io.BytesIO(rawconfig), yaml.SafeLoader)
if schema:
check_config_schema(config, schema)
return errorhandlify(config, filename)
def insert_schema_path(schema, path, datatype, highleveldatatype):
if len(path) == 1:
schema[path[0]] = (datatype, highleveldatatype)
else:
if path[0] not in schema:
schema[path[0]] = {}
insert_schema_path(schema[path[0]], path[1:], datatype, highleveldatatype)
def transform_schema(in_schema):
schema = {}
for (rawpath, datatype, highleveldatatype) in in_schema:
path = rawpath.split("/")
insert_schema_path(schema, path, datatype, highleveldatatype)
return schema
def check_config_schema(config, schema):
transformed_schema = transform_schema(schema)
error = check_config_schema_part(config, transformed_schema)
if error:
print >>sys.stderr, "error:", error
sys.exit(1)
def check_config_schema_part(term, schema, path=[]):
joined_path = render_path(path)
if isinstance(term, basestring):
(schema_lowlevel, schema_highlevel) = schema
if schema_lowlevel != "string":
return "expected %s at %s, not a string" % (schema_lowlevel, joined_path,)
return None
elif isinstance(term, int):
(schema_lowlevel, schema_highlevel) = schema
if schema_lowlevel != "integer":
return "expected %s at %s, not an integer" % (schema_lowlevel, joined_path,)
return None
elif isinstance(term, dict):
if not isinstance(schema, dict):
return "expected %s at %s, not a key" % (schema, joined_path,)
for k, v in term.items():
schema_part = schema.get(k)
if schema_part == None and len(schema.keys()) == 1 and schema.keys()[0].startswith("*"):
schema_part = schema[schema.keys()[0]]
if schema_part == None:
return "configuration key '%s' at %s unknown" % (k, joined_path)
result = check_config_schema_part(v, schema_part, path + [k])
if result:
return result
return None
elif isinstance(term, list):
if not isinstance(schema, dict):
return "expected %s at %s, not a list" % (schema, joined_path,)
schema_part = schema.get("[]")
if schema_part == None:
return "expected dict at %s, not a list" % (joined_path,)
for i, e in enumerate(term, start=1):
result = check_config_schema_part(e, schema_part, path + ["item %d" % i])
if result:
return result
return None
else:
print >>sys.stderr, "unknown type", type(term)
sys.exit(1)
def read_config(filename, schema=None):
config = yaml.load(open(filename), yaml.SafeLoader)
if schema:
check_config_schema(config, schema)
return errorhandlify(config, filename)
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