#!/usr/bin/env python3

# translate_ciphers.py
#
# Copyright The Mbed TLS Contributors
# SPDX-License-Identifier: Apache-2.0
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
# Purpose
#
# Translate ciphersuite names in MBedTLS format to OpenSSL and GNUTLS
# standards.
#
# Format and analyse strings past in via input arguments to match
# the expected strings utilised in compat.sh.
#
# sys.argv[1] should be "g" or "o" for GNUTLS or OpenSSL.
# sys.argv[2] should be a string containing one or more
# ciphersuite names.

import re
import sys

def translate_gnutls(m_cipher):
    # Remove "TLS-"
    # Replace "-WITH-" with ":+"
    # Remove "EDE"
    m_cipher = "+" + m_cipher[4:]
    m_cipher = m_cipher.replace("-WITH-", ":+")
    m_cipher = m_cipher.replace("-EDE", "")

    # SHA == SHA1, if the last 3 chars are SHA append 1
    if m_cipher[-3:] == "SHA":
        m_cipher = m_cipher+"1"

    # CCM or CCM-8 should be followed by ":+AEAD"
    if "CCM" in m_cipher:
        m_cipher = m_cipher+":+AEAD"

    # Replace the last "-" with ":+"
    # Replace "GCM:+SHAxyz" with "GCM:+AEAD"
    else:
        index=m_cipher.rindex("-")
        m_cipher = m_cipher[:index]+":+"+m_cipher[index+1:]
        m_cipher = re.sub(r"GCM\:\+SHA\d\d\d", "GCM:+AEAD", m_cipher)

    return m_cipher

def translate_ossl(m_cipher):
    # Remove "TLS-"
    # Remove "WITH"
    m_cipher = m_cipher[4:]
    m_cipher = m_cipher.replace("-WITH", "")

    # Remove the "-" from "ABC-xyz"
    m_cipher = m_cipher.replace("AES-", "AES")
    m_cipher = m_cipher.replace("CAMELLIA-", "CAMELLIA")
    m_cipher = m_cipher.replace("ARIA-", "ARIA")

    # Remove "RSA" if it is at the beginning
    if m_cipher[:4] == "RSA-":
        m_cipher = m_cipher[4:]

    # For all circumstances outside of PSK
    if "PSK" not in m_cipher:
        m_cipher = m_cipher.replace("-EDE", "")
        m_cipher = m_cipher.replace("3DES-CBC", "DES-CBC3")

        # Remove "CBC" if it is not prefixed by DES
        if "CBC" in m_cipher:
            index = m_cipher.rindex("CBC")
            if m_cipher[index-4:index-1] != "DES":
                m_cipher = m_cipher.replace("CBC-", "")

    # ECDHE-RSA-ARIA does not exist in OpenSSL
    m_cipher = m_cipher.replace("ECDHE-RSA-ARIA", "ECDHE-ARIA")

    # POLY1305 should not be followed by anything
    if "POLY1305" in m_cipher:
        index = m_cipher.rindex("POLY1305")
        m_cipher=m_cipher[:index+8]

    # If DES is being used, Replace DHE with EDH
    if "DES" in m_cipher and "DHE" in m_cipher and "ECDHE" not in m_cipher:
        m_cipher = m_cipher.replace("DHE", "EDH")

    return m_cipher

def format_ciphersuite_names(mode, ciphers):
    try:
        t = {"g": translate_gnutls, "o": translate_ossl}[mode]
        return " ".join(t(c) for c in ciphers.split())
    except Exception as E:
        if E != mode: print(E)
        else: print("Incorrect use of argument 1, should be either \"g\" or \"o\"")
        sys.exit(1)

def main():
    if len(sys.argv) != 3:
        print("""Incorrect number of arguments.
The first argument with either an \"o\" for OpenSSL or \"g\" for GNUTLS.
The second argument should a single space seperated string of MBedTLS ciphersuite names""")
        sys.exit(1)
    print(format_ciphersuite_names(sys.argv[1], sys.argv[2]))
    sys.exit(0)

if __name__ == "__main__":
    main()