common.py

""" ./QA/common.py - common code for QA """

import contextlib
import json
import os
import shutil
import socket
import subprocess


def execute(args):
    """Execute a specified command"""
    subprocess.run(args)


def execute_jafar_and_miniooni(ooni_exe, outfile, experiment, tag, args):
    """Executes jafar and miniooni. Returns the test keys."""
    tmpoutfile = "/tmp/{}".format(outfile)
    with contextlib.suppress(FileNotFoundError):
        os.remove(tmpoutfile)  # just in case
    execute(
        [
            # Disable ASLR
            "setarch",
            "--addr-no-randomize",
            # Run cachegrind
            "valgrind",
            "--tool=cachegrind",
            "--I1=32768,8,64",
            "--D1=32768,8,64",
            "--LL=8388608,16,64",
            "--cachegrind-out-file=cachegrind.out",
            # Run jafar
            "./jafar",
            "-main-command",
            "./QA/minioonilike.py {} -n -o '{}' --home /tmp {}".format(
                ooni_exe, tmpoutfile, experiment
            ),
            "-main-user",
            "nobody",  # should be present on Unix
            "-tag",
            tag,
        ]
        + args
    )
    shutil.copy(tmpoutfile, outfile)
    result = read_result(outfile)
    assert isinstance(result, dict)
    assert isinstance(result["test_keys"], dict)
    return result["test_keys"]


def read_result(outfile):
    """Reads the result of an experiment"""
    return json.load(open(outfile, "rb"))


def test_keys(result):
    """Returns just the test keys of a specific result"""
    return result["test_keys"]


def check_maybe_binary_value(value):
    """Make sure a maybe binary value is correct"""
    assert isinstance(value, str) or (
        isinstance(value, dict)
        and value["format"] == "base64"
        and isinstance(value["data"], str)
    )


def with_free_port(func):
    """This function executes |func| passing it a port number on localhost
    which is bound but not listening for new connections"""
    # See <https://stackoverflow.com/a/45690594>
    with contextlib.closing(socket.socket(socket.AF_INET, socket.SOCK_STREAM)) as sock:
        sock.bind(("127.0.0.1", 0))
        sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
        func(sock.getsockname()[1])