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import nacl.signing
import json
import base64
import requests
import sys
import srvlookup
def encode_base64(input_bytes):
"""Encode bytes as a base64 string without any padding."""
input_len = len(input_bytes)
output_len = 4 * ((input_len + 2) // 3) + (input_len + 2) % 3 - 2
output_bytes = base64.b64encode(input_bytes)
output_string = output_bytes[:output_len].decode("ascii")
return output_string
def decode_base64(input_string):
"""Decode a base64 string to bytes inferring padding from the length of the
string."""
input_bytes = input_string.encode("ascii")
input_len = len(input_bytes)
padding = b"=" * (3 - ((input_len + 3) % 4))
output_len = 3 * ((input_len + 2) // 4) + (input_len + 2) % 4 - 2
output_bytes = base64.b64decode(input_bytes + padding)
return output_bytes[:output_len]
def encode_canonical_json(value):
return json.dumps(
value,
# Encode code-points outside of ASCII as UTF-8 rather than \u escapes
ensure_ascii=False,
# Remove unecessary white space.
separators=(',',':'),
# Sort the keys of dictionaries.
sort_keys=True,
# Encode the resulting unicode as UTF-8 bytes.
).encode("UTF-8")
def sign_json(json_object, signing_key, signing_name):
signatures = json_object.pop("signatures", {})
unsigned = json_object.pop("unsigned", None)
signed = signing_key.sign(encode_canonical_json(json_object))
signature_base64 = encode_base64(signed.signature)
key_id = "%s:%s" % (signing_key.alg, signing_key.version)
signatures.setdefault(signing_name, {})[key_id] = signature_base64
json_object["signatures"] = signatures
if unsigned is not None:
json_object["unsigned"] = unsigned
return json_object
NACL_ED25519 = "ed25519"
def decode_signing_key_base64(algorithm, version, key_base64):
"""Decode a base64 encoded signing key
Args:
algorithm (str): The algorithm the key is for (currently "ed25519").
version (str): Identifies this key out of the keys for this entity.
key_base64 (str): Base64 encoded bytes of the key.
Returns:
A SigningKey object.
"""
if algorithm == NACL_ED25519:
key_bytes = decode_base64(key_base64)
key = nacl.signing.SigningKey(key_bytes)
key.version = version
key.alg = NACL_ED25519
return key
else:
raise ValueError("Unsupported algorithm %s" % (algorithm,))
def read_signing_keys(stream):
"""Reads a list of keys from a stream
Args:
stream : A stream to iterate for keys.
Returns:
list of SigningKey objects.
"""
keys = []
for line in stream:
algorithm, version, key_base64 = line.split()
keys.append(decode_signing_key_base64(algorithm, version, key_base64))
return keys
def lookup(destination, path):
if ":" in destination:
return "https://%s%s" % (destination, path)
else:
try:
srv = srvlookup.lookup("matrix", "tcp", destination)[0]
return "https://%s:%d%s" % (srv.host, srv.port, path)
except:
return "https://%s:%d%s" % (destination, 8448, path)
def get_json(origin_name, origin_key, destination, path):
request_json = {
"method": "GET",
"uri": path,
"origin": origin_name,
"destination": destination,
}
signed_json = sign_json(request_json, origin_key, origin_name)
authorization_headers = []
for key, sig in signed_json["signatures"][origin_name].items():
authorization_headers.append(bytes(
"X-Matrix origin=%s,key=\"%s\",sig=\"%s\"" % (
origin_name, key, sig,
)
))
result = requests.get(
lookup(destination, path),
headers={"Authorization": authorization_headers[0]},
verify=False,
)
return result.json()
def main():
origin_name, keyfile, destination, path = sys.argv[1:]
with open(keyfile) as f:
key = read_signing_keys(f)[0]
result = get_json(
origin_name, key, destination, "/_matrix/federation/v1/" + path
)
json.dump(result, sys.stdout)
if __name__ == "__main__":
main()