import logging
import os
from argparse import ArgumentDefaultsHelpFormatter
from math import ceil
from sbws.globals import (
DAY_SECS,
GENERATE_PERIOD,
NUM_MIN_RESULTS,
PROP276_ROUND_DIG,
SBWS_SCALE_CONSTANT,
SBWS_SCALING,
TORFLOW_BW_MARGIN,
TORFLOW_SCALING,
fail_hard,
)
from sbws.lib import destination
from sbws.lib.resultdump import load_recent_results_in_datadir
from sbws.lib.v3bwfile import V3BWFile
from sbws.util.timestamp import now_fname
log = logging.getLogger(__name__)
[docs]def gen_parser(sub):
d = (
"Generate a v3bw file based on recent results. A v3bw file is the "
"file Tor directory authorities want to read and base their "
"bandwidth votes on. "
"To avoid inconsistent reads, configure tor with "
'"V3BandwidthsFile /path/to/latest.v3bw". '
"(latest.v3bw is an atomically created symlink in the same "
"directory as output.) "
"If the file is transferred to another host, it should be written to "
"a temporary path, then renamed to the V3BandwidthsFile path.\n"
"The default scaling method is torflow's one. To use different"
"scaling methods or no scaling, see the options."
)
p = sub.add_parser(
"generate",
description=d,
formatter_class=ArgumentDefaultsHelpFormatter,
)
p.add_argument(
"--output",
default=None,
type=str,
help="If specified, write the v3bw here instead of what is"
"specified in the configuration",
)
# The reason for --scale-constant defaulting to 7500 is because at one
# time, torflow happened to generate output that averaged to 7500 bw units
# per relay. We wanted the ability to try to be like torflow. See
# https://lists.torproject.org/pipermail/tor-dev/2018-March/013049.html
p.add_argument(
"--scale-constant",
default=SBWS_SCALE_CONSTANT,
type=int,
help="When scaling bw weights, scale them using this const "
"multiplied by the number of measured relays",
)
p.add_argument(
"--scale-sbws",
action="store_true",
help="If specified, do not use bandwidth values as they "
"are, but scale them such that we have a budget of "
"scale_constant * num_measured_relays = bandwidth to give "
"out, and we do so proportionally",
)
p.add_argument(
"-t",
"--scale-torflow",
action="store_true",
default=True,
help="If specified, scale measurements using torflow's "
"method. This option is kept for compatibility with older "
"versions and it is silently ignored, since it is the "
"default.",
)
p.add_argument(
"-w",
"--raw",
action="store_true",
help="If specified, do use bandwidth raw measurements "
"without any scaling.",
)
p.add_argument(
"-m",
"--torflow-bw-margin",
default=TORFLOW_BW_MARGIN,
type=float,
help="Cap maximum bw when scaling as Torflow. ",
)
p.add_argument(
"-r",
"--round-digs",
"--torflow-round-digs",
default=PROP276_ROUND_DIG,
type=int,
help="Number of most significant digits to round bw.",
)
p.add_argument(
"-p",
"--secs-recent",
default=None,
type=int,
help="How many secs in the past are results being "
"still considered. Default is {} secs. If not scaling "
"as Torflow the default is data_period in the "
"configuration.".format(GENERATE_PERIOD),
)
p.add_argument(
"-a",
"--secs-away",
default=DAY_SECS,
type=int,
help="How many secs results have to be away from each " "other.",
)
p.add_argument(
"-n",
"--min-num",
default=NUM_MIN_RESULTS,
type=int,
help="Minimum number of a results to consider them.",
)
return p
[docs]def main(args, conf):
os.makedirs(conf.getpath("paths", "v3bw_dname"), exist_ok=True)
datadir = conf.getpath("paths", "datadir")
if not os.path.isdir(datadir):
fail_hard("%s does not exist", datadir)
if args.scale_constant < 1:
fail_hard("--scale-constant must be positive")
if args.torflow_bw_margin < 0:
fail_hard("toflow-bw-margin must be major than 0.")
if args.scale_sbws:
scaling_method = SBWS_SCALING
elif args.raw:
scaling_method = None
else:
# sbws will scale as torflow until we have a better algorithm for
# scaling (#XXX)
scaling_method = TORFLOW_SCALING
if args.secs_recent:
fresh_days = ceil(args.secs_recent / 24 / 60 / 60)
elif scaling_method == TORFLOW_SCALING:
fresh_days = ceil(GENERATE_PERIOD / 24 / 60 / 60)
else:
fresh_days = conf.getint("general", "data_period")
reset_bw_ipv4_changes = conf.getboolean("general", "reset_bw_ipv4_changes")
reset_bw_ipv6_changes = conf.getboolean("general", "reset_bw_ipv6_changes")
results = load_recent_results_in_datadir(
fresh_days,
datadir,
on_changed_ipv4=reset_bw_ipv4_changes,
on_changed_ipv6=reset_bw_ipv6_changes,
)
if len(results) < 1:
log.warning(
"No recent results, so not generating anything. (Have you "
"ran sbws scanner recently?)"
)
return
state_fpath = conf.getpath("paths", "state_fname")
consensus_path = os.path.join(
conf.getpath("tor", "datadir"), "cached-consensus"
)
# Accept None as scanner_country to be compatible with older versions.
scanner_country = conf["scanner"].get("country")
destinations_countries = destination.parse_destinations_countries(conf)
bw_file = V3BWFile.from_results(
results,
scanner_country,
destinations_countries,
state_fpath,
args.scale_constant,
scaling_method,
torflow_cap=args.torflow_bw_margin,
round_digs=args.round_digs,
secs_recent=args.secs_recent,
secs_away=args.secs_away,
min_num=args.min_num,
consensus_path=consensus_path,
)
output = args.output or conf.getpath("paths", "v3bw_fname").format(
now_fname()
)
bw_file.write(output)
bw_file.info_stats