# -*- coding: utf-8 -*-

# Copyright (c) 2020 Detlev Offenbach <detlev@die-offenbachs.de>
#

"""
Module implementing a check for use of SSL/TLS with insecure protocols.
"""

#
# This is a modified version of the one found in the bandit package.
#
# Original Copyright 2014 Hewlett-Packard Development Company, L.P.
#
# SPDX-License-Identifier: Apache-2.0
#

from Security.SecurityDefaults import SecurityDefaults


def getChecks():
    """
    Public method to get a dictionary with checks handled by this module.
    
    @return dictionary containing checker lists containing checker function and
        list of codes
    @rtype dict
    """
    return {
        "Call": [
            (checkInsecureSslProtocolVersion, ("S502",)),
            (checkSslWithoutVersion, ("S504",)),
        ],
        "FunctionDef": [
            (checkInsecureSslDefaults, ("S503",)),
        ],
    }


def checkInsecureSslProtocolVersion(reportError, context, config):
    """
    Function to check for use of insecure SSL protocol version.
    
    @param reportError function to be used to report errors
    @type func
    @param context security context object
    @type SecurityContext
    @param config dictionary with configuration data
    @type dict
    """
    if config and "insecure_ssl_protocol_versions" in config:
        insecureProtocolVersions = config["insecure_ssl_protocol_versions"]
    else:
        insecureProtocolVersions = SecurityDefaults[
            "insecure_ssl_protocol_versions"]
    
    if context.callFunctionNameQual == 'ssl.wrap_socket':
        if context.checkCallArgValue('ssl_version', insecureProtocolVersions):
            reportError(
                context.getLinenoForCallArg('ssl_version') - 1,
                context.getOffsetForCallArg('ssl_version'),
                "S502.1",
                "H",
                "H",
            )
    
    elif context.callFunctionNameQual == 'pyOpenSSL.SSL.Context':
        if context.checkCallArgValue('method', insecureProtocolVersions):
            reportError(
                context.getLinenoForCallArg('method') - 1,
                context.getOffsetForCallArg('method'),
                "S502.2",
                "H",
                "H",
            )
    
    elif (
        context.callFunctionNameQual != 'ssl.wrap_socket' and
        context.callFunctionNameQual != 'pyOpenSSL.SSL.Context'
    ):
        if context.checkCallArgValue('method', insecureProtocolVersions):
            reportError(
                context.getLinenoForCallArg('method') - 1,
                context.getOffsetForCallArg('method'),
                "S502.3",
                "H",
                "H",
            )
        
        elif context.checkCallArgValue('ssl_version',
                                       insecureProtocolVersions):
            reportError(
                context.getLinenoForCallArg('ssl_version') - 1,
                context.getOffsetForCallArg('ssl_version'),
                "S502.3",
                "H",
                "H",
            )


def checkInsecureSslDefaults(reportError, context, config):
    """
    Function to check for SSL use with insecure defaults specified.
    
    @param reportError function to be used to report errors
    @type func
    @param context security context object
    @type SecurityContext
    @param config dictionary with configuration data
    @type dict
    """
    if config and "insecure_ssl_protocol_versions" in config:
        insecureProtocolVersions = config["insecure_ssl_protocol_versions"]
    else:
        insecureProtocolVersions = SecurityDefaults[
            "insecure_ssl_protocol_versions"]
    
    for default in context.functionDefDefaultsQual:
        val = default.split(".")[-1]
        if val in insecureProtocolVersions:
            reportError(
                context.node.lineno - 1,
                context.node.col_offset,
                "S503",
                "M",
                "M",
            )


def checkSslWithoutVersion(reportError, context, config):
    """
    Function to check for SSL use with no version specified.
    
    @param reportError function to be used to report errors
    @type func
    @param context security context object
    @type SecurityContext
    @param config dictionary with configuration data
    @type dict
    """
    if context.callFunctionNameQual == 'ssl.wrap_socket':
        if context.checkCallArgValue('ssl_version') is None:
            # checkCallArgValue() returns False if the argument is found
            # but does not match the supplied value (or the default None).
            # It returns None if the argument passed doesn't exist. This
            # tests for that (ssl_version is not specified).
            reportError(
                context.node.lineno - 1,
                context.node.col_offset,
                "S504",
                "L",
                "M",
            )
