115 lines
3.6 KiB
Python
115 lines
3.6 KiB
Python
"""Utility functions and classes for the stix2 library."""
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import datetime as dt
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import json
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from dateutil import parser
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import pytz
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# Sentinel value for properties that should be set to the current time.
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# We can't use the standard 'default' approach, since if there are multiple
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# timestamps in a single object, the timestamps will vary by a few microseconds.
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NOW = object()
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class STIXdatetime(dt.datetime):
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def __new__(cls, *args, **kwargs):
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precision = kwargs.pop('precision', None)
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if isinstance(args[0], dt.datetime): # Allow passing in a datetime object
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dttm = args[0]
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args = (dttm.year, dttm.month, dttm.day, dttm.hour, dttm.minute,
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dttm.second, dttm.microsecond, dttm.tzinfo)
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# self will be an instance of STIXdatetime, not dt.datetime
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self = dt.datetime.__new__(cls, *args, **kwargs)
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self.precision = precision
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return self
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def get_timestamp():
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return STIXdatetime.now(tz=pytz.UTC)
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def format_datetime(dttm):
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# 1. Convert to timezone-aware
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# 2. Convert to UTC
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# 3. Format in ISO format
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# 4. Ensure correct precision
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# 4a. Add subsecond value if non-zero and precision not defined
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# 5. Add "Z"
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if dttm.tzinfo is None or dttm.tzinfo.utcoffset(dttm) is None:
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# dttm is timezone-naive; assume UTC
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zoned = pytz.utc.localize(dttm)
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else:
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zoned = dttm.astimezone(pytz.utc)
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ts = zoned.strftime("%Y-%m-%dT%H:%M:%S")
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ms = zoned.strftime("%f")
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precision = getattr(dttm, "precision", None)
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if precision == 'second':
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pass # Alredy precise to the second
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elif precision == "millisecond":
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ts = ts + '.' + ms[:3]
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elif zoned.microsecond > 0:
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ts = ts + '.' + ms.rstrip("0")
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return ts + "Z"
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def parse_into_datetime(value, precision=None):
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if isinstance(value, dt.date):
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if hasattr(value, 'hour'):
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ts = value
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else:
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# Add a time component
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ts = dt.datetime.combine(value, dt.time(0, 0, tzinfo=pytz.utc))
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else:
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# value isn't a date or datetime object so assume it's a string
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try:
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parsed = parser.parse(value)
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except (TypeError, ValueError):
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# Unknown format
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raise ValueError("must be a datetime object, date object, or "
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"timestamp string in a recognizable format.")
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if parsed.tzinfo:
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ts = parsed.astimezone(pytz.utc)
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else:
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# Doesn't have timezone info in the string; assume UTC
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ts = pytz.utc.localize(parsed)
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# Ensure correct precision
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if not precision:
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return ts
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ms = ts.microsecond
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if precision == 'second':
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ts = ts.replace(microsecond=0)
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elif precision == 'millisecond':
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ms_len = len(str(ms))
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if ms_len > 3:
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# Truncate to millisecond precision
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factor = 10 ** (ms_len - 3)
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ts = ts.replace(microsecond=(ts.microsecond // factor) * factor)
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else:
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ts = ts.replace(microsecond=0)
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return STIXdatetime(ts, precision=precision)
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def get_dict(data):
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"""Return data as a dictionary.
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Input can be a dictionary, string, or file-like object.
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"""
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if type(data) is dict:
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return data
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else:
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try:
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return json.loads(data)
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except TypeError:
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pass
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try:
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return json.load(data)
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except AttributeError:
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pass
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try:
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return dict(data)
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except (ValueError, TypeError):
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raise ValueError("Cannot convert '%s' to dictionary." % str(data))
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