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#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""
Helpers for encoding/decoding server_message_data values.
These are Base64URL-encoded proto3 messages with shape:
- field 1: string UUID (36 chars)
- field 3: google.protobuf.Timestamp (1=seconds, 2=nanos)
Supports UUID_ONLY, TIMESTAMP_ONLY, and UUID_AND_TIMESTAMP.
"""
from typing import Dict, Optional, Tuple
import base64
from datetime import datetime, timezone
try:
from zoneinfo import ZoneInfo # Python 3.9+
except Exception:
ZoneInfo = None # type: ignore
def _b64url_decode_padded(s: str) -> bytes:
t = s.replace("-", "+").replace("_", "/")
pad = (-len(t)) % 4
if pad:
t += "=" * pad
return base64.b64decode(t)
def _b64url_encode_nopad(b: bytes) -> str:
return base64.urlsafe_b64encode(b).decode("ascii").rstrip("=")
def _read_varint(buf: bytes, i: int) -> Tuple[int, int]:
shift = 0
val = 0
while i < len(buf):
b = buf[i]
i += 1
val |= (b & 0x7F) << shift
if not (b & 0x80):
return val, i
shift += 7
if shift > 63:
break
raise ValueError("invalid varint")
def _write_varint(v: int) -> bytes:
out = bytearray()
vv = int(v)
while True:
to_write = vv & 0x7F
vv >>= 7
if vv:
out.append(to_write | 0x80)
else:
out.append(to_write)
break
return bytes(out)
def _make_key(field_no: int, wire_type: int) -> bytes:
return _write_varint((field_no << 3) | wire_type)
def _decode_timestamp(buf: bytes) -> Tuple[Optional[int], Optional[int]]:
i = 0
seconds: Optional[int] = None
nanos: Optional[int] = None
while i < len(buf):
key, i = _read_varint(buf, i)
field_no = key >> 3
wt = key & 0x07
if wt == 0:
val, i = _read_varint(buf, i)
if field_no == 1:
seconds = int(val)
elif field_no == 2:
nanos = int(val)
elif wt == 2:
ln, i2 = _read_varint(buf, i)
i = i2 + ln
elif wt == 1:
i += 8
elif wt == 5:
i += 4
else:
break
return seconds, nanos
def _encode_timestamp(seconds: Optional[int], nanos: Optional[int]) -> bytes:
parts = bytearray()
if seconds is not None:
parts += _make_key(1, 0)
parts += _write_varint(int(seconds))
if nanos is not None:
parts += _make_key(2, 0)
parts += _write_varint(int(nanos))
return bytes(parts)
def decode_server_message_data(b64url: str) -> Dict:
try:
raw = _b64url_decode_padded(b64url)
except Exception as e:
return {"error": f"base64url decode failed: {e}"}
i = 0
uuid: Optional[str] = None
seconds: Optional[int] = None
nanos: Optional[int] = None
while i < len(raw):
key, i = _read_varint(raw, i)
field_no = key >> 3
wt = key & 0x07
if wt == 2:
ln, i2 = _read_varint(raw, i)
i = i2
data = raw[i:i+ln]
i += ln
if field_no == 1:
try:
uuid = data.decode("utf-8")
except Exception:
uuid = None
elif field_no == 3:
s, n = _decode_timestamp(data)
if s is not None:
seconds = s
if n is not None:
nanos = n
elif wt == 0:
_, i = _read_varint(raw, i)
elif wt == 1:
i += 8
elif wt == 5:
i += 4
else:
break
iso_utc: Optional[str] = None
iso_ny: Optional[str] = None
if seconds is not None:
micros = int((nanos or 0) / 1000)
dt = datetime.fromtimestamp(int(seconds), tz=timezone.utc).replace(microsecond=micros)
iso_utc = dt.isoformat().replace("+00:00", "Z")
if ZoneInfo is not None:
try:
iso_ny = dt.astimezone(ZoneInfo("America/New_York")).isoformat()
except Exception:
iso_ny = None
if uuid and (seconds is not None or nanos is not None):
t = "UUID_AND_TIMESTAMP"
elif uuid:
t = "UUID_ONLY"
elif seconds is not None or nanos is not None:
t = "TIMESTAMP_ONLY"
else:
t = "UNKNOWN"
return {
"uuid": uuid,
"seconds": seconds,
"nanos": nanos,
"iso_utc": iso_utc,
"iso_ny": iso_ny,
"type": t,
}
def encode_server_message_data(uuid: Optional[str] = None,
seconds: Optional[int] = None,
nanos: Optional[int] = None) -> str:
parts = bytearray()
if uuid:
b = uuid.encode("utf-8")
parts += _make_key(1, 2)
parts += _write_varint(len(b))
parts += b
if seconds is not None or nanos is not None:
ts = _encode_timestamp(seconds, nanos)
parts += _make_key(3, 2)
parts += _write_varint(len(ts))
parts += ts
return _b64url_encode_nopad(bytes(parts)) |