Source code for onbasca.base.models.bridge

# SPDX-FileCopyrightText: 2022 The Tor Project, Inc.
#
# SPDX-License-Identifier: BSD-3-Clause
"""Bridge base model."""
import logging
import re

from django.db import models

from onbasca.bridgeline import parse_bridge_line

from . import BaseManager, BaseModel

logger = logging.getLogger(__name__)




def fingerprint_from_bridgeline(bridgeline):
    """
    Obtain the bridge fingerprint from a bridge line.

    From ``7. Displaying Bridge Information``
    (https://gitlab.torproject.org/tpo/core/torspec/-/blob/main/bridgedb-spec.txt#L357)
    Bridges are formatted as::

        <address:port> NL

    Pluggable transports are formatted as::

        <transportname> SP <address:port> [SP arglist] NL

    Example::
        - with transport::
          obfs4 <ip>:<port> <fingerprint> cert=<cert> iat-mode=<iat-mode>
        - without transport::
          <ip>:<port> <fingerprint>

    """
    # Regular expression from:
    # https://gitlab.torproject.org/tpo/anti-censorship/bridgestrap/-/blob/719bed120f6d01829d04c19e21a80fc9a04f393e/tor.go#L41  # noqa
    fp_re = re.compile("([A-F0-9]{40})")
    # Assume any line as ``(transport) <ip>:<port> (<fingerprint>)`` is valid.
    fp = re.findall(fp_re, bridgeline)
    if len(fp) == 1:
        logger.debug("bridgeline contains fingerprint.")
        return fp[0]
    # Regular expression from:
    # https://gitlab.torproject.org/tpo/anti-censorship/bridgestrap/-/blob/719bed120f6d01829d04c19e21a80fc9a04f393e/cache.go#L17  # noqa
    ip_port_re = re.compile("[0-9a-z\[\]\.:]+:[0-9]{1,5}")  # noqa:W605
    ip_port = re.findall(ip_port_re, bridgeline)
    if len(ip_port) == 1:
        logger.warning("Not found fingerprint in bridgeline but found ip:port")
        return ip_port[0]
    logger.warning("No fingerprint nor ip found in bridgeline")
    return None





class BridgeManagerBase(BaseManager):


    def from_bridgeline(self, bridgeline):
        """Create a bridge from a bridgeline"""
        logger.debug("Creating bridge from bridgeline %s", bridgeline)
        bridgeline_kwargs = parse_bridge_line(bridgeline)
        if not bridgeline_kwargs:
            return "bridgeline is not valid.", False
        # if there're several `kwargs`, then the fingerprint is in the 2nd
        # position.
        if (
            len([kwarg for kwarg in bridgeline_kwargs if kwarg is not None])
            > 1
        ):
            fingerprint = bridgeline_kwargs[1]
        # otherwise, use the addrport as the fingerprint, which is in the 1st
        # position.
        else:
            fingerprint = bridgeline_kwargs[0]
        bridge, created = self.update_or_create(
            fingerprint=fingerprint,
            defaults={"bridgeline": bridgeline},
        )
        logger.info("Bridge %s created %s", bridge, created)
        return bridge, created






class BridgeBase(BaseModel):


    class Meta:
        abstract = True


    objects = BridgeManagerBase()
    fingerprint = models.CharField(primary_key=True, max_length=40)
    # What's the max and min length?, 154?
    bridgeline = models.CharField(max_length=255, null=True, blank=True)

    def __str__(self):
        return "{}".format(self.fingerprint)