169 lines
4.4 KiB
Python
169 lines
4.4 KiB
Python
"""Feed models"""
|
|
|
|
from base64 import b64encode
|
|
from collections import OrderedDict, namedtuple
|
|
import datetime
|
|
from hashlib import sha256
|
|
|
|
from simplejson import dumps, loads
|
|
|
|
from ssb.util import tag
|
|
|
|
OrderedMsg = namedtuple("OrderedMsg", ("previous", "author", "sequence", "timestamp", "hash", "content"))
|
|
|
|
|
|
class NoPrivateKeyException(Exception):
|
|
"""Exception to raise when a private key is not available"""
|
|
|
|
|
|
def to_ordered(data):
|
|
"""Convert a dictionary to an ``OrderedDict``"""
|
|
|
|
smsg = OrderedMsg(**data)
|
|
|
|
return OrderedDict((k, getattr(smsg, k)) for k in smsg._fields)
|
|
|
|
|
|
def get_millis_1970():
|
|
"""Get the UNIX timestamp in milliseconds"""
|
|
|
|
return int(datetime.datetime.utcnow().timestamp() * 1000)
|
|
|
|
|
|
class Feed:
|
|
"""Base class for feeds"""
|
|
|
|
def __init__(self, public_key):
|
|
self.public_key = public_key
|
|
|
|
@property
|
|
def id(self):
|
|
"""The identifier of the feed"""
|
|
|
|
return tag(self.public_key).decode("ascii")
|
|
|
|
def sign(self, msg):
|
|
"""Sign a message"""
|
|
|
|
raise NoPrivateKeyException("Cannot use remote identity to sign (no private key!)")
|
|
|
|
|
|
class LocalFeed(Feed):
|
|
"""Class representing a local feed"""
|
|
|
|
def __init__(self, private_key): # pylint: disable=super-init-not-called
|
|
self.private_key = private_key
|
|
|
|
@property
|
|
def public_key(self):
|
|
"""The public key of the feed"""
|
|
|
|
return self.private_key.verify_key
|
|
|
|
def sign(self, msg):
|
|
"""Sign a message for this feed"""
|
|
|
|
return self.private_key.sign(msg).signature
|
|
|
|
|
|
class Message:
|
|
"""Base class for SSB messages"""
|
|
|
|
def __init__( # pylint: disable=too-many-arguments
|
|
self, feed, content, signature=None, sequence=1, timestamp=None, previous=None
|
|
):
|
|
self.feed = feed
|
|
self.content = content
|
|
|
|
if signature is None:
|
|
raise ValueError("signature can't be None")
|
|
|
|
self.signature = signature
|
|
|
|
self.previous = previous
|
|
if self.previous:
|
|
self.sequence = self.previous.sequence + 1
|
|
else:
|
|
self.sequence = sequence
|
|
|
|
self.timestamp = get_millis_1970() if timestamp is None else timestamp
|
|
|
|
@classmethod
|
|
def parse(cls, data, feed):
|
|
"""Parse raw message data"""
|
|
|
|
obj = loads(data, object_pairs_hook=OrderedDict)
|
|
msg = cls(feed, obj["content"], timestamp=obj["timestamp"])
|
|
|
|
return msg
|
|
|
|
def serialize(self, add_signature=True):
|
|
"""Serialize the message"""
|
|
|
|
return dumps(self.to_dict(add_signature=add_signature), indent=2).encode("utf-8")
|
|
|
|
def to_dict(self, add_signature=True):
|
|
"""Convert the message to a dictionary"""
|
|
|
|
obj = to_ordered(
|
|
{
|
|
"previous": self.previous.key if self.previous else None,
|
|
"author": self.feed.id,
|
|
"sequence": self.sequence,
|
|
"timestamp": self.timestamp,
|
|
"hash": "sha256",
|
|
"content": self.content,
|
|
}
|
|
)
|
|
|
|
if add_signature:
|
|
obj["signature"] = self.signature
|
|
|
|
return obj
|
|
|
|
def verify(self, signature):
|
|
"""Verify the signature of the message"""
|
|
|
|
return self.signature == signature
|
|
|
|
@property
|
|
def hash(self):
|
|
"""The cryptographic hash of the message"""
|
|
|
|
hash_ = sha256(self.serialize()).digest()
|
|
return b64encode(hash_).decode("ascii") + ".sha256"
|
|
|
|
@property
|
|
def key(self):
|
|
"""The key of the message"""
|
|
|
|
return "%" + self.hash
|
|
|
|
|
|
class LocalMessage(Message):
|
|
"""Class representing a local message"""
|
|
|
|
def __init__( # pylint: disable=too-many-arguments,super-init-not-called
|
|
self, feed, content, signature=None, sequence=1, timestamp=None, previous=None
|
|
):
|
|
self.feed = feed
|
|
self.content = content
|
|
|
|
self.previous = previous
|
|
if self.previous:
|
|
self.sequence = self.previous.sequence + 1
|
|
else:
|
|
self.sequence = sequence
|
|
|
|
self.timestamp = get_millis_1970() if timestamp is None else timestamp
|
|
|
|
if signature is None:
|
|
self.signature = self._sign()
|
|
else:
|
|
self.signature = signature
|
|
|
|
def _sign(self):
|
|
# ensure ordering of keys and indentation of 2 characters, like ssb-keys
|
|
data = self.serialize(add_signature=False)
|
|
return (b64encode(bytes(self.feed.sign(data))) + b".sig.ed25519").decode("ascii")
|