__init__.py

#!/usr/bin/env python3
#
# Copyright 2017-2018 Amazon.com, Inc. and its affiliates. All Rights Reserved.
#
# Licensed under the MIT License. See the LICENSE accompanying this file
# for the specific language governing permissions and limitations under
# the License.
#
#
# Copy this script to /sbin/mount.efs and make sure it is executable.
#
# You will be able to mount an EFS file system by its short name, by adding it
# to /etc/fstab. The syntax of an fstab entry is:
#
# [Device] [Mount Point] [File System Type] [Options] [Dump] [Pass]
#
# Add an entry like this:
#
#   fs-deadbeef     /mount_point    efs     _netdev         0   0
#
# Using the 'efs' type will cause '/sbin/mount.efs' to be called by 'mount -a'
# for this file system. The '_netdev' option tells the init system that the
# 'efs' type is a networked file system type. This has been tested with systemd
# (Amazon Linux 2, CentOS 7, RHEL 7, Debian 9, and Ubuntu 16.04), and upstart
# (Amazon Linux 2017.09).
#
# Once there is an entry in fstab, the file system can be mounted with:
#
#   sudo mount /mount_point
#
# The script will add recommended mount options, if not provided in fstab.

import base64
import errno
import hashlib
import hmac
import json
import logging
import os
import platform
import pwd
import random
import re
import socket
import subprocess
import sys
import threading
import time

from contextlib import contextmanager
from datetime import datetime, timedelta
from logging.handlers import RotatingFileHandler

try:
    from configparser import ConfigParser, NoOptionError, NoSectionError
except ImportError:
    import ConfigParser
    from ConfigParser import NoOptionError, NoSectionError

try:
    from urllib.parse import quote_plus
except ImportError:
    from urllib import quote_plus

try:
    from urllib.request import urlopen, Request
    from urllib.error import URLError, HTTPError
    from urllib.parse import urlencode
except ImportError:
    from urllib2 import URLError, HTTPError, build_opener, urlopen, Request, HTTPHandler
    from urllib import urlencode

try:
    import botocore.session
    from botocore.exceptions import ClientError, NoCredentialsError, EndpointConnectionError
    BOTOCORE_PRESENT = True
except ImportError:
    BOTOCORE_PRESENT = False


VERSION = '1.30.1'
SERVICE = 'elasticfilesystem'

CLONE_NEWNET = 0x40000000
CONFIG_FILE = '/etc/amazon/efs/efs-utils.conf'
CONFIG_SECTION = 'mount'
CLIENT_INFO_SECTION = 'client-info'
CLIENT_SOURCE_STR_LEN_LIMIT = 100
# Cloudwatchlog agent dict includes cloudwatchlog botocore client, cloudwatchlog group name, cloudwatchlog stream name
CLOUDWATCHLOG_AGENT = None
CLOUDWATCH_LOG_SECTION = 'cloudwatch-log'
DEFAULT_CLOUDWATCH_LOG_GROUP = '/aws/efs/utils'
DEFAULT_RETENTION_DAYS = 14
DEFAULT_UNKNOWN_VALUE = 'unknown'

LOG_DIR = '/var/log/amazon/efs'
LOG_FILE = 'mount.log'

STATE_FILE_DIR = '/var/run/efs'

PRIVATE_KEY_FILE = '/etc/amazon/efs/privateKey.pem'
DATE_ONLY_FORMAT = '%Y%m%d'
SIGV4_DATETIME_FORMAT = '%Y%m%dT%H%M%SZ'
CERT_DATETIME_FORMAT = '%y%m%d%H%M%SZ'

AWS_CREDENTIALS_FILE = os.path.expanduser(os.path.join('~' + pwd.getpwuid(os.getuid()).pw_name, '.aws', 'credentials'))
AWS_CONFIG_FILE = os.path.expanduser(os.path.join('~' + pwd.getpwuid(os.getuid()).pw_name, '.aws', 'config'))

CA_CONFIG_BODY = """dir = %s
RANDFILE = $dir/database/.rand

[ ca ]
default_ca = local_ca

[ local_ca ]
database = $dir/database/index.txt
serial = $dir/database/serial
private_key = %s
cert = $dir/certificate.pem
new_certs_dir = $dir/certs
default_md = sha256
preserve = no
policy = efsPolicy
x509_extensions = v3_ca

[ efsPolicy ]
CN = supplied

[ req ]
prompt = no
distinguished_name = req_distinguished_name

[ req_distinguished_name ]
CN = %s

%s

%s

%s
"""

# SigV4 Auth
ALGORITHM = 'AWS4-HMAC-SHA256'
AWS4_REQUEST = 'aws4_request'

HTTP_REQUEST_METHOD = 'GET'
CANONICAL_URI = '/'
CANONICAL_HEADERS_DICT = {
    'host': '%s'
}
CANONICAL_HEADERS = '\n'.join(['%s:%s' % (k, v) for k, v in sorted(CANONICAL_HEADERS_DICT.items())])
SIGNED_HEADERS = ';'.join(CANONICAL_HEADERS_DICT.keys())
REQUEST_PAYLOAD = ''

FS_ID_RE = re.compile('^(?P<fs_id>fs-[0-9a-f]+)$')
EFS_FQDN_RE = re.compile(r'^((?P<az>[a-z0-9-]+)\.)?(?P<fs_id>fs-[0-9a-f]+)\.efs\.'
                         r'(?P<region>[a-z0-9-]+)\.(?P<dns_name_suffix>[a-z0-9.]+)$')
AP_ID_RE = re.compile('^fsap-[0-9a-f]{17}$')

CREDENTIALS_KEYS = ['AccessKeyId', 'SecretAccessKey', 'Token']
ECS_URI_ENV = 'AWS_CONTAINER_CREDENTIALS_RELATIVE_URI'
ECS_TASK_METADATA_API = 'http://169.254.170.2'
WEB_IDENTITY_ROLE_ARN_ENV = 'AWS_ROLE_ARN'
WEB_IDENTITY_TOKEN_FILE_ENV = 'AWS_WEB_IDENTITY_TOKEN_FILE'
STS_ENDPOINT_URL_FORMAT = 'https://sts.{}.amazonaws.com/'
INSTANCE_METADATA_TOKEN_URL = 'http://169.254.169.254/latest/api/token'
INSTANCE_METADATA_SERVICE_URL = 'http://169.254.169.254/latest/dynamic/instance-identity/document/'
INSTANCE_IAM_URL = 'http://169.254.169.254/latest/meta-data/iam/security-credentials/'
SECURITY_CREDS_ECS_URI_HELP_URL = 'https://docs.aws.amazon.com/AmazonECS/latest/developerguide/task-iam-roles.html'
SECURITY_CREDS_WEBIDENTITY_HELP_URL = 'https://docs.aws.amazon.com/eks/latest/userguide/iam-roles-for-service-accounts.html'
SECURITY_CREDS_IAM_ROLE_HELP_URL = 'https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/iam-roles-for-amazon-ec2.html'

DEFAULT_STUNNEL_VERIFY_LEVEL = 2
DEFAULT_STUNNEL_CAFILE = '/etc/amazon/efs/efs-utils.crt'

NOT_BEFORE_MINS = 15
NOT_AFTER_HOURS = 3

EFS_ONLY_OPTIONS = [
    'accesspoint',
    'awscredsuri',
    'awsprofile',
    'az',
    'cafile',
    'iam',
    'netns',
    'noocsp',
    'ocsp',
    'tls',
    'tlsport',
    'verify'
]

UNSUPPORTED_OPTIONS = [
    'capath'
]

STUNNEL_GLOBAL_CONFIG = {
    'fips': 'no',
    'foreground': 'yes',
    'socket': [
        'l:SO_REUSEADDR=yes',
        'a:SO_BINDTODEVICE=lo',
    ],
}

STUNNEL_EFS_CONFIG = {
    'client': 'yes',
    'accept': '127.0.0.1:%s',
    'connect': '%s:2049',
    'sslVersion': 'TLSv1.2',
    'renegotiation': 'no',
    'TIMEOUTbusy': '20',
    'TIMEOUTclose': '0',
    'TIMEOUTidle': '70',
    'delay': 'yes',
}

WATCHDOG_SERVICE = 'amazon-efs-mount-watchdog'
# MacOS instances use plist files. This files needs to be loaded on launchctl (init system of MacOS)
WATCHDOG_SERVICE_PLIST_PATH = '/Library/LaunchAgents/amazon-efs-mount-watchdog.plist'
SYSTEM_RELEASE_PATH = '/etc/system-release'
OS_RELEASE_PATH = '/etc/os-release'
RHEL8_RELEASE_NAME = 'Red Hat Enterprise Linux release 8'
CENTOS8_RELEASE_NAME = 'CentOS Linux release 8'
FEDORA_RELEASE_NAME = 'Fedora release'
OPEN_SUSE_LEAP_RELEASE_NAME = 'openSUSE Leap'
SUSE_RELEASE_NAME = 'SUSE Linux Enterprise Server'
MACOS_BIG_SUR_RELEASE = 'macOS-11'

SKIP_NO_LIBWRAP_RELEASES = [RHEL8_RELEASE_NAME, CENTOS8_RELEASE_NAME, FEDORA_RELEASE_NAME, OPEN_SUSE_LEAP_RELEASE_NAME,
                            SUSE_RELEASE_NAME, MACOS_BIG_SUR_RELEASE]

# MacOS does not support the property of Socket SO_BINDTODEVICE in stunnel configuration
SKIP_NO_SO_BINDTODEVICE_RELEASES = [MACOS_BIG_SUR_RELEASE]

MAC_OS_PLATFORM_LIST = ['darwin']
# MacOS Versions : Big Sur - 20.*, Catalina - 19.*, Mojave - 18.*. Catalina and Mojave are not supported for now
MAC_OS_SUPPORTED_VERSION_LIST = ['20']


def errcheck(ret, func, args):
    from ctypes import get_errno
    if ret == -1:
        e = get_errno()
        raise OSError(e, os.strerror(e))


def setns(fd, nstype):
    from ctypes import CDLL
    libc = CDLL('libc.so.6', use_errno=True)
    libc.setns.errcheck = errcheck
    if hasattr(fd, 'fileno'):
        fd = fd.fileno()
    return libc.setns(fd, nstype)


class NetNS(object):
    # Open sockets from given network namespace: stackoverflow.com/questions/28846059
    def __init__(self, nspath):
        self.original_nspath = '/proc/%d/ns/net' % os.getpid()
        self.target_nspath = nspath

    def __enter__(self):
        self.original_namespace = open(self.original_nspath)
        with open(self.target_nspath) as fd:
            setns(fd, CLONE_NEWNET)

    def __exit__(self, *args):
        setns(self.original_namespace, CLONE_NEWNET)
        self.original_namespace.close()


def fatal_error(user_message, log_message=None, exit_code=1):
    if log_message is None:
        log_message = user_message

    sys.stderr.write('%s\n' % user_message)
    logging.error(log_message)
    publish_cloudwatch_log(CLOUDWATCHLOG_AGENT, 'Mount failed, %s' % log_message)
    sys.exit(exit_code)


def get_target_region(config):
    def _fatal_error(message):
        fatal_error('Error retrieving region. Please set the "region" parameter in the efs-utils configuration file.', message)

    metadata_exception = 'Unknown error'
    try:
        return config.get(CONFIG_SECTION, 'region')
    except NoOptionError:
        pass

    try:
        return get_region_from_instance_metadata()
    except Exception as e:
        metadata_exception = e
        logging.warning('Region not found in config file and metadata service call failed, falling back '
                        'to legacy "dns_name_format" check')

    try:
        region = get_region_from_legacy_dns_format(config)
        sys.stdout.write('Warning: region obtained from "dns_name_format" field. Please set the "region" '
                         'parameter in the efs-utils configuration file.')
        return region
    except Exception:
        logging.warning('Legacy check for region in "dns_name_format" failed')

    _fatal_error(metadata_exception)


def get_region_from_instance_metadata():
    instance_identity = get_instance_identity_info_from_instance_metadata('region')

    if not instance_identity:
        raise Exception("Cannot retrieve region from instance_metadata")

    return instance_identity


def get_instance_identity_info_from_instance_metadata(property):
    ec2_metadata_unsuccessful_resp = 'Unsuccessful retrieval of EC2 metadata at %s.' % INSTANCE_METADATA_SERVICE_URL
    ec2_metadata_url_error_msg = 'Unable to reach %s to retrieve EC2 instance metadata.' % INSTANCE_METADATA_SERVICE_URL
    instance_identity = url_request_helper(INSTANCE_METADATA_SERVICE_URL, ec2_metadata_unsuccessful_resp,
                                           ec2_metadata_url_error_msg, retry_with_new_header_token=True)
    if instance_identity:
        try:
            return instance_identity[property]
        except KeyError as e:
            logging.warning('%s not present in %s: %s' % (property, instance_identity, e))
        except TypeError as e:
            logging.warning('response %s is not a json object: %s' % (instance_identity, e))

    return None


def get_region_from_legacy_dns_format(config):
    """
    For backwards compatibility check dns_name_format to obtain the target region. This functionality
    should only be used if region is not present in the config file and metadata calls fail.
    """
    dns_name_format = config.get(CONFIG_SECTION, 'dns_name_format')
    if '{region}' not in dns_name_format:
        split_dns_name_format = dns_name_format.split('.')
        if '{dns_name_suffix}' in dns_name_format:
            return split_dns_name_format[-2]
        elif 'amazonaws.com' in dns_name_format:
            return split_dns_name_format[-3]
    raise Exception('Region not found in dns_name_format')


def get_aws_ec2_metadata_token():
    try:
        opener = build_opener(HTTPHandler)
        request = Request(INSTANCE_METADATA_TOKEN_URL)
        request.add_header('X-aws-ec2-metadata-token-ttl-seconds', 21600)
        request.get_method = lambda: 'PUT'
        res = opener.open(request)
        return res.read()
    except NameError:
        headers = {'X-aws-ec2-metadata-token-ttl-seconds': 21600}
        req = Request(INSTANCE_METADATA_TOKEN_URL, headers=headers, method='PUT')
        res = urlopen(req)
        return res.read()


def get_aws_security_credentials(use_iam, region, awsprofile=None, aws_creds_uri=None):
    """
    Lookup AWS security credentials (access key ID and secret access key). Adapted credentials provider chain from:
    https://boto3.amazonaws.com/v1/documentation/api/latest/guide/configuration.html and
    https://docs.aws.amazon.com/sdk-for-java/v1/developer-guide/credentials.html
    """
    if not use_iam:
        return None, None

    # attempt to lookup AWS security credentials through the credentials URI the ECS agent generated
    if aws_creds_uri:
        return get_aws_security_credentials_from_ecs(aws_creds_uri, True)

    # attempt to lookup AWS security credentials in AWS credentials file (~/.aws/credentials)
    # and configs file (~/.aws/config) with given awsprofile
    if awsprofile:
        return get_aws_security_credentials_from_awsprofile(awsprofile, True)

    # attempt to lookup AWS security credentials through AWS_CONTAINER_CREDENTIALS_RELATIVE_URI environment variable
    if ECS_URI_ENV in os.environ:
        credentials, credentials_source = get_aws_security_credentials_from_ecs(os.environ[ECS_URI_ENV], False)
        if credentials and credentials_source:
            return credentials, credentials_source

    # attempt to lookup AWS security credentials through AssumeRoleWithWebIdentity
    # (e.g. for IAM Role for Service Accounts (IRSA) approach on EKS)
    if WEB_IDENTITY_ROLE_ARN_ENV in os.environ and WEB_IDENTITY_TOKEN_FILE_ENV in os.environ:
        credentials, credentials_source = get_aws_security_credentials_from_webidentity(
            os.environ[WEB_IDENTITY_ROLE_ARN_ENV],
            os.environ[WEB_IDENTITY_TOKEN_FILE_ENV],
            region,
            False
        )
        if credentials and credentials_source:
            return credentials, credentials_source

    # attempt to lookup AWS security credentials with IAM role name attached to instance
    # through IAM role name security credentials lookup uri
    iam_role_name = get_iam_role_name()
    if iam_role_name:
        credentials, credentials_source = get_aws_security_credentials_from_instance_metadata(iam_role_name)
        if credentials and credentials_source:
            return credentials, credentials_source

    error_msg = 'AWS Access Key ID and Secret Access Key are not found in AWS credentials file (%s), config file (%s), ' \
                'from ECS credentials relative uri, or from the instance security credentials service' % \
                (AWS_CREDENTIALS_FILE, AWS_CONFIG_FILE)
    fatal_error(error_msg, error_msg)


def get_aws_security_credentials_from_awsprofile(awsprofile, is_fatal=False):
    for file_path in [AWS_CREDENTIALS_FILE, AWS_CONFIG_FILE]:
        if os.path.exists(file_path):
            credentials = credentials_file_helper(file_path, awsprofile)
            if credentials['AccessKeyId']:
                return credentials, os.path.basename(file_path) + ':' + awsprofile

    # Fail if credentials cannot be fetched from the given awsprofile
    if is_fatal:
        log_message = 'AWS security credentials not found in %s or %s under named profile [%s]' % \
                    (AWS_CREDENTIALS_FILE, AWS_CONFIG_FILE, awsprofile)
        fatal_error(log_message)
    else:
        return None, None


def get_aws_security_credentials_from_ecs(aws_creds_uri, is_fatal=False):
    ecs_uri = ECS_TASK_METADATA_API + aws_creds_uri
    ecs_unsuccessful_resp = 'Unsuccessful retrieval of AWS security credentials at %s.' % ecs_uri
    ecs_url_error_msg = 'Unable to reach %s to retrieve AWS security credentials. See %s for more info.' \
                        % (ecs_uri, SECURITY_CREDS_ECS_URI_HELP_URL)
    ecs_security_dict = url_request_helper(ecs_uri, ecs_unsuccessful_resp, ecs_url_error_msg)

    if ecs_security_dict and all(k in ecs_security_dict for k in CREDENTIALS_KEYS):
        return ecs_security_dict, 'ecs:' + aws_creds_uri

    # Fail if credentials cannot be fetched from the given aws_creds_uri
    if is_fatal:
        fatal_error(ecs_unsuccessful_resp, ecs_unsuccessful_resp)
    else:
        return None, None


def get_aws_security_credentials_from_webidentity(role_arn, token_file, region, is_fatal=False):
    try:
        with open(token_file, 'r') as f:
            token = f.read()
    except Exception as e:
        if is_fatal:
            unsuccessful_resp = 'Error reading token file %s: %s' % (token_file, e)
            fatal_error(unsuccessful_resp, unsuccessful_resp)
        else:
            return None, None

    STS_ENDPOINT_URL = STS_ENDPOINT_URL_FORMAT.format(region)
    webidentity_url = STS_ENDPOINT_URL + '?' + urlencode({
        'Version': '2011-06-15',
        'Action': 'AssumeRoleWithWebIdentity',
        'RoleArn': role_arn,
        'RoleSessionName': 'efs-mount-helper',
        'WebIdentityToken': token
    })

    unsuccessful_resp = 'Unsuccessful retrieval of AWS security credentials at %s.' % STS_ENDPOINT_URL
    url_error_msg = 'Unable to reach %s to retrieve AWS security credentials. See %s for more info.' % \
                    (STS_ENDPOINT_URL, SECURITY_CREDS_WEBIDENTITY_HELP_URL)
    resp = url_request_helper(webidentity_url, unsuccessful_resp, url_error_msg, headers={'Accept': 'application/json'})

    if resp:
        creds = resp \
                .get('AssumeRoleWithWebIdentityResponse', {}) \
                .get('AssumeRoleWithWebIdentityResult', {}) \
                .get('Credentials', {})
        if all(k in creds for k in ['AccessKeyId', 'SecretAccessKey', 'SessionToken']):
            return {
                'AccessKeyId': creds['AccessKeyId'],
                'SecretAccessKey': creds['SecretAccessKey'],
                'Token': creds['SessionToken']
            }, 'webidentity:' + ','.join([role_arn, token_file])

    # Fail if credentials cannot be fetched from the given aws_creds_uri
    if is_fatal:
        fatal_error(unsuccessful_resp, unsuccessful_resp)
    else:
        return None, None


def get_aws_security_credentials_from_instance_metadata(iam_role_name):
    security_creds_lookup_url = INSTANCE_IAM_URL + iam_role_name
    unsuccessful_resp = 'Unsuccessful retrieval of AWS security credentials at %s.' % security_creds_lookup_url
    url_error_msg = 'Unable to reach %s to retrieve AWS security credentials. See %s for more info.' % \
                    (security_creds_lookup_url, SECURITY_CREDS_IAM_ROLE_HELP_URL)
    iam_security_dict = url_request_helper(security_creds_lookup_url, unsuccessful_resp,
                                           url_error_msg, retry_with_new_header_token=True)

    if iam_security_dict and all(k in iam_security_dict for k in CREDENTIALS_KEYS):
        return iam_security_dict, 'metadata:'
    else:
        return None, None


def get_iam_role_name():
    iam_role_unsuccessful_resp = 'Unsuccessful retrieval of IAM role name at %s.' % INSTANCE_IAM_URL
    iam_role_url_error_msg = 'Unable to reach %s to retrieve IAM role name. See %s for more info.' % \
                             (INSTANCE_IAM_URL, SECURITY_CREDS_IAM_ROLE_HELP_URL)
    iam_role_name = url_request_helper(INSTANCE_IAM_URL, iam_role_unsuccessful_resp,
                                       iam_role_url_error_msg, retry_with_new_header_token=True)
    return iam_role_name


def credentials_file_helper(file_path, awsprofile):
    aws_credentials_configs = read_config(file_path)
    credentials = {'AccessKeyId': None, 'SecretAccessKey': None, 'Token': None}

    try:
        access_key = aws_credentials_configs.get(awsprofile, 'aws_access_key_id')
        secret_key = aws_credentials_configs.get(awsprofile, 'aws_secret_access_key')
        session_token = aws_credentials_configs.get(awsprofile, 'aws_session_token')

        credentials['AccessKeyId'] = access_key
        credentials['SecretAccessKey'] = secret_key
        credentials['Token'] = session_token
    except NoOptionError as e:
        if 'aws_access_key_id' in str(e) or 'aws_secret_access_key' in str(e):
            logging.debug('aws_access_key_id or aws_secret_access_key not found in %s under named profile [%s]', file_path,
                          awsprofile)
        if 'aws_session_token' in str(e):
            logging.debug('aws_session_token not found in %s', file_path)
            credentials['AccessKeyId'] = aws_credentials_configs.get(awsprofile, 'aws_access_key_id')
            credentials['SecretAccessKey'] = aws_credentials_configs.get(awsprofile, 'aws_secret_access_key')
    except NoSectionError:
        logging.debug('No [%s] section found in config file %s', awsprofile, file_path)

    return credentials


def get_aws_profile(options, use_iam):
    awsprofile = options.get('awsprofile')
    if not awsprofile and use_iam:
        for file_path in [AWS_CREDENTIALS_FILE, AWS_CONFIG_FILE]:
            aws_credentials_configs = read_config(file_path)
            # check if aws access key id is found under [default] section in current file and return 'default' if so
            try:
                access_key = aws_credentials_configs.get('default', 'aws_access_key_id')
                if access_key is not None:
                    return 'default'
            except (NoSectionError, NoOptionError):
                continue

    return awsprofile


def url_request_helper(url, unsuccessful_resp, url_error_msg, headers={}, retry_with_new_header_token=False):
    try:
        req = Request(url)
        for k, v in headers.items():
            req.add_header(k, v)
        request_resp = urlopen(req, timeout=1)

        return get_resp_obj(request_resp, url, unsuccessful_resp)
    except HTTPError as e:
        # For instance enable with IMDSv2, Unauthorized 401 error will be thrown,
        # to retrieve metadata, the header should embeded with metadata token
        if e.code == 401 and retry_with_new_header_token:
            token = get_aws_ec2_metadata_token()
            req.add_header('X-aws-ec2-metadata-token', token)
            request_resp = urlopen(req, timeout=1)
            return get_resp_obj(request_resp, url, unsuccessful_resp)
        err_msg = 'Unable to reach the url at %s: status=%d, reason is %s' % (url, e.code, e.reason)
    except URLError as e:
        err_msg = 'Unable to reach the url at %s, reason is %s' % (url, e.reason)

    if err_msg:
        logging.debug('%s %s', url_error_msg, err_msg)
    return None


def get_resp_obj(request_resp, url, unsuccessful_resp):
    if request_resp.getcode() != 200:
        logging.debug(unsuccessful_resp + ' %s: ResponseCode=%d', url, request_resp.getcode())
        return None

    resp_body = request_resp.read()
    resp_body_type = type(resp_body)
    try:
        if resp_body_type is str:
            resp_dict = json.loads(resp_body)
        else:
            resp_dict = json.loads(resp_body.decode(request_resp.headers.get_content_charset() or 'us-ascii'))

        return resp_dict
    except ValueError as e:
        logging.info('ValueError parsing "%s" into json: %s. Returning response body.' % (str(resp_body), e))
        return resp_body if resp_body_type is str else resp_body.decode('utf-8')


def parse_options(options):
    opts = {}
    for o in options.split(','):
        if '=' in o:
            k, v = o.split('=')
            opts[k] = v
        else:
            opts[o] = None
    return opts


def get_tls_port_range(config):
    lower_bound = config.getint(CONFIG_SECTION, 'port_range_lower_bound')
    upper_bound = config.getint(CONFIG_SECTION, 'port_range_upper_bound')

    if lower_bound >= upper_bound:
        fatal_error('Configuration option "port_range_upper_bound" defined as %d '
                    'must be strictly greater than "port_range_lower_bound" defined as %d.'
                    % (upper_bound, lower_bound))

    return lower_bound, upper_bound


def choose_tls_port(config, options):
    if 'tlsport' in options:
        ports_to_try = [int(options['tlsport'])]
    else:
        lower_bound, upper_bound = get_tls_port_range(config)

        tls_ports = list(range(lower_bound, upper_bound))

        # Choose a random midpoint, and then try ports in-order from there
        mid = random.randrange(len(tls_ports))

        ports_to_try = tls_ports[mid:] + tls_ports[:mid]
        assert len(tls_ports) == len(ports_to_try)

    if 'netns' not in options:
        tls_port = find_tls_port_in_range(ports_to_try)
    else:
        with NetNS(nspath=options['netns']):
            tls_port = find_tls_port_in_range(ports_to_try)

    if tls_port:
        return tls_port

    if 'tlsport' in options:
        fatal_error('Specified port [%s] is unavailable. Try selecting a different port.' % options['tlsport'])
    else:
        fatal_error('Failed to locate an available port in the range [%d, %d], try specifying a different port range in %s'
                    % (lower_bound, upper_bound, CONFIG_FILE))


def find_tls_port_in_range(ports_to_try):
    sock = socket.socket()
    for tls_port in ports_to_try:
        try:
            logging.info("binding %s", tls_port)
            sock.bind(('localhost', tls_port))
            sock.close()
            return tls_port
        except socket.error as e:
            logging.info(e)
            continue
    sock.close()
    return None


def is_ocsp_enabled(config, options):
    if 'ocsp' in options:
        return True
    elif 'noocsp' in options:
        return False
    else:
        return config.getboolean(CONFIG_SECTION, 'stunnel_check_cert_validity')


def get_mount_specific_filename(fs_id, mountpoint, tls_port):
    return '%s.%s.%d' % (fs_id, os.path.abspath(mountpoint).replace(os.sep, '.').lstrip('.'), tls_port)


def serialize_stunnel_config(config, header=None):
    lines = []

    if header:
        lines.append('[%s]' % header)

    for k, v in config.items():
        if type(v) is list:
            for item in v:
                lines.append('%s = %s' % (k, item))
        else:
            lines.append('%s = %s' % (k, v))

    return lines


def add_stunnel_ca_options(efs_config, config, options, region):
    if 'cafile' in options:
        stunnel_cafile = options['cafile']
    else:
        try:
            config_section = get_config_section(config, region)
            stunnel_cafile = config.get(config_section, 'stunnel_cafile')
            logging.debug("Using stunnel_cafile %s in config section [%s]", stunnel_cafile, config_section)
        except NoOptionError:
            logging.debug('No CA file configured, using default CA file %s', DEFAULT_STUNNEL_CAFILE)
            stunnel_cafile = DEFAULT_STUNNEL_CAFILE

    if not os.path.exists(stunnel_cafile):
        fatal_error('Failed to find certificate authority file for verification',
                    'Failed to find CAfile "%s"' % stunnel_cafile)

    efs_config['CAfile'] = stunnel_cafile


def get_config_section(config, region):
    region_specific_config_section = '%s.%s' % (CONFIG_SECTION, region)
    if config.has_section(region_specific_config_section):
        config_section = region_specific_config_section
    else:
        config_section = CONFIG_SECTION
    return config_section


def is_stunnel_option_supported(stunnel_output, stunnel_option_name):
    supported = False
    for line in stunnel_output:
        if line.startswith(stunnel_option_name):
            supported = True
            break

    if not supported:
        logging.warning('stunnel does not support "%s"', stunnel_option_name)

    return supported


def get_version_specific_stunnel_options():
    stunnel_command = [_stunnel_bin(), '-help']
    proc = subprocess.Popen(stunnel_command, stdout=subprocess.PIPE, stderr=subprocess.PIPE, close_fds=True)
    proc.wait()
    _, err = proc.communicate()

    stunnel_output = err.splitlines()

    check_host_supported = is_stunnel_option_supported(stunnel_output, b'checkHost')
    ocsp_aia_supported = is_stunnel_option_supported(stunnel_output, b'OCSPaia')

    return check_host_supported, ocsp_aia_supported


def _stunnel_bin():
    return find_command_path('stunnel',
                             'Please install it following the instructions at '
                             'https://docs.aws.amazon.com/efs/latest/ug/using-amazon-efs-utils.html#upgrading-stunnel')


def find_command_path(command, install_method):
    try:
        env_path = '/sbin:/usr/sbin:/usr/local/sbin:/root/bin:/usr/local/bin:/usr/bin:/bin'
        os.putenv('PATH', env_path)
        path = subprocess.check_output(['which', command])
    except subprocess.CalledProcessError as e:
        fatal_error('Failed to locate %s in %s - %s' % (command, env_path, install_method), e)
    return path.strip().decode()


def get_system_release_version():
    # MacOS does not maintain paths /etc/os-release and /etc/sys-release
    if check_if_platform_is_mac():
        return platform.platform()

    try:
        with open(SYSTEM_RELEASE_PATH) as f:
            return f.read().strip()
    except IOError:
        logging.debug('Unable to read %s', SYSTEM_RELEASE_PATH)

    try:
        with open(OS_RELEASE_PATH) as f:
            for line in f:
                if 'PRETTY_NAME' in line:
                    return line.split('=')[1].strip()
    except IOError:
        logging.debug('Unable to read %s', OS_RELEASE_PATH)

    return DEFAULT_UNKNOWN_VALUE


def write_stunnel_config_file(config, state_file_dir, fs_id, mountpoint, tls_port, dns_name, verify_level, ocsp_enabled,
                              options, region, log_dir=LOG_DIR, cert_details=None):
    """
    Serializes stunnel configuration to a file. Unfortunately this does not conform to Python's config file format, so we have to
    hand-serialize it.
    """

    mount_filename = get_mount_specific_filename(fs_id, mountpoint, tls_port)

    system_release_version = get_system_release_version()
    global_config = dict(STUNNEL_GLOBAL_CONFIG)
    if any(release in system_release_version for release in SKIP_NO_SO_BINDTODEVICE_RELEASES):
        global_config['socket'].remove('a:SO_BINDTODEVICE=lo')

    if config.getboolean(CONFIG_SECTION, 'stunnel_debug_enabled'):
        global_config['debug'] = 'debug'

        if config.has_option(CONFIG_SECTION, 'stunnel_logs_file'):
            global_config['output'] = config.get(CONFIG_SECTION, 'stunnel_logs_file').replace('{fs_id}', fs_id)
        else:
            global_config['output'] = os.path.join(log_dir, '%s.stunnel.log' % mount_filename)

    efs_config = dict(STUNNEL_EFS_CONFIG)
    efs_config['accept'] = efs_config['accept'] % tls_port
    efs_config['connect'] = efs_config['connect'] % dns_name
    efs_config['verify'] = verify_level
    if verify_level > 0:
        add_stunnel_ca_options(efs_config, config, options, region)

    if cert_details:
        efs_config['cert'] = cert_details['certificate']
        efs_config['key'] = cert_details['privateKey']

    check_host_supported, ocsp_aia_supported = get_version_specific_stunnel_options()

    tls_controls_message = 'WARNING: Your client lacks sufficient controls to properly enforce TLS. Please upgrade stunnel, ' \
        'or disable "%%s" in %s.\nSee %s for more detail.' % (CONFIG_FILE,
                                                              'https://docs.aws.amazon.com/console/efs/troubleshooting-tls')

    if config.getboolean(CONFIG_SECTION, 'stunnel_check_cert_hostname'):
        if check_host_supported:
            # Stunnel checkHost option checks if the specified DNS host name or wildcard matches any of the provider in peer
            # certificate's CN fields, after introducing the AZ field in dns name, the host name in the stunnel config file
            # is not valid, remove the az info there
            efs_config['checkHost'] = dns_name[dns_name.index(fs_id):]
        else:
            fatal_error(tls_controls_message % 'stunnel_check_cert_hostname')

    # Only use the config setting if the override is not set
    if ocsp_enabled:
        if ocsp_aia_supported:
            efs_config['OCSPaia'] = 'yes'
        else:
            fatal_error(tls_controls_message % 'stunnel_check_cert_validity')

    if not any(release in system_release_version for release in SKIP_NO_LIBWRAP_RELEASES):
        efs_config['libwrap'] = 'no'

    stunnel_config = '\n'.join(serialize_stunnel_config(global_config) + serialize_stunnel_config(efs_config, 'efs'))
    logging.debug('Writing stunnel configuration:\n%s', stunnel_config)

    stunnel_config_file = os.path.join(state_file_dir, 'stunnel-config.%s' % mount_filename)

    with open(stunnel_config_file, 'w') as f:
        f.write(stunnel_config)

    return stunnel_config_file


def write_tls_tunnel_state_file(fs_id, mountpoint, tls_port, tunnel_pid, command, files, state_file_dir, cert_details=None):
    """
    Return the name of the temporary file containing TLS tunnel state, prefixed with a '~'. This file needs to be renamed to a
    non-temporary version following a successful mount.
    """
    state_file = '~' + get_mount_specific_filename(fs_id, mountpoint, tls_port)

    state = {
        'pid': tunnel_pid,
        'cmd': command,
        'files': files,
    }

    if cert_details:
        state.update(cert_details)

    with open(os.path.join(state_file_dir, state_file), 'w') as f:
        json.dump(state, f)

    return state_file


def test_tunnel_process(tunnel_proc, fs_id):
    tunnel_proc.poll()
    if tunnel_proc.returncode is not None:
        out, err = tunnel_proc.communicate()
        fatal_error('Failed to initialize TLS tunnel for %s' % fs_id,
                    'Failed to start TLS tunnel (errno=%d). stdout="%s" stderr="%s"'
                    % (tunnel_proc.returncode, out.strip(), err.strip()))


def poll_tunnel_process(tunnel_proc, fs_id, mount_completed):
    """
    poll the tunnel process health every .5s during the mount attempt to fail fast if the tunnel dies - since this is not called
    from the main thread, if the tunnel fails, exit uncleanly with os._exit
    """
    while not mount_completed.is_set():
        try:
            test_tunnel_process(tunnel_proc, fs_id)
        except SystemExit as e:
            os._exit(e.code)
        mount_completed.wait(.5)


def get_init_system(comm_file='/proc/1/comm'):
    init_system = DEFAULT_UNKNOWN_VALUE
    if not check_if_platform_is_mac():
        try:
            with open(comm_file) as f:
                init_system = f.read().strip()
        except IOError:
            logging.warning('Unable to read %s', comm_file)
    else:
        init_system = 'launchd'

    logging.debug('Identified init system: %s', init_system)
    return init_system


def check_network_target(fs_id):
    with open(os.devnull, 'w') as devnull:
        if not check_if_platform_is_mac():
            rc = subprocess.call(['systemctl', 'status', 'network.target'], stdout=devnull, stderr=devnull, close_fds=True)
        else:
            rc = subprocess.call(['sudo', 'ifconfig', 'en0'], stdout=devnull, stderr=devnull, close_fds=True)

    if rc != 0:
        fatal_error('Failed to mount %s because the network was not yet available, add "_netdev" to your mount options' % fs_id,
                    exit_code=0)


def check_network_status(fs_id, init_system):
    if init_system != 'systemd':
        logging.debug('Not testing network on non-systemd init systems')
        return

    check_network_target(fs_id)


def start_watchdog(init_system):
    if init_system == 'init':
        proc = subprocess.Popen(
                ['/sbin/status', WATCHDOG_SERVICE], stdout=subprocess.PIPE, stderr=subprocess.PIPE, close_fds=True)
        status, _ = proc.communicate()
        if 'stop' in str(status):
            with open(os.devnull, 'w') as devnull:
                subprocess.Popen(['/sbin/start', WATCHDOG_SERVICE], stdout=devnull, stderr=devnull, close_fds=True)
        elif 'start' in str(status):
            logging.debug('%s is already running', WATCHDOG_SERVICE)

    elif init_system == 'systemd':
        rc = subprocess.call(['systemctl', 'is-active', '--quiet', WATCHDOG_SERVICE], close_fds=True)
        if rc != 0:
            with open(os.devnull, 'w') as devnull:
                subprocess.Popen(['systemctl', 'start', WATCHDOG_SERVICE], stdout=devnull, stderr=devnull, close_fds=True)
        else:
            logging.debug('%s is already running', WATCHDOG_SERVICE)

    elif init_system == 'launchd':
        rc = subprocess.Popen(['sudo', 'launchctl', 'list', WATCHDOG_SERVICE], stdout=subprocess.PIPE,
                              stderr=subprocess.PIPE, close_fds=True)
        if rc != 0:
            if not os.path.exists(WATCHDOG_SERVICE_PLIST_PATH):
                fatal_error('Watchdog plist file missing. Copy the watchdog plist file in directory /Library/LaunchAgents')
            with open(os.devnull, 'w') as devnull:
                subprocess.Popen(['sudo', 'launchctl', 'load', WATCHDOG_SERVICE_PLIST_PATH], stdout=devnull,
                                 stderr=devnull, close_fds=True)
        else:
            logging.debug('%s is already running', WATCHDOG_SERVICE)

    else:
        error_message = 'Could not start %s, unrecognized init system "%s"' % (WATCHDOG_SERVICE, init_system)
        sys.stderr.write('%s\n' % error_message)
        logging.warning(error_message)


def create_required_directory(config, directory):
    mode = 0o750
    try:
        mode_str = config.get(CONFIG_SECTION, 'state_file_dir_mode')
        try:
            mode = int(mode_str, 8)
        except ValueError:
            logging.warning('Bad state_file_dir_mode "%s" in config file "%s"', mode_str, CONFIG_FILE)
    except NoOptionError:
        pass

    try:
        os.makedirs(directory, mode)
    except OSError as e:
        if errno.EEXIST != e.errno or not os.path.isdir(directory):
            raise


@contextmanager
def bootstrap_tls(config, init_system, dns_name, fs_id, mountpoint, options, state_file_dir=STATE_FILE_DIR):
    tls_port = choose_tls_port(config, options)
    # override the tlsport option so that we can later override the port the NFS client uses to connect to stunnel.