#!/usr/bin/python3

"""
* File: clsha2
* Version  : 1.0
* License  : BSD
*
*
* Copyright (c) 2022 - 2024
*	Ralf Senderek, Ireland.  All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in the
*    documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
*    must display the following acknowledgement:
*	   This product includes software developed by Ralf Senderek.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
"""


import sys, os
from base64 import *
from binascii import *

try:
     from cryptlib_py import *
except:
     ERR_IMPORT = """
     The python3 library is not installed. You need to install
     the packages cryptlib-python3 and cryptlib.
     You will find them for a variety of operating systems here:
            https://senderek.ie/cryptlib
     or in the Fedora repository.
     """
     print(ERR_IMPORT)
     exit (5)


Version = "clsha2 version 1.0"
HashSize = 32
OK = 0
ERR_NOBYTES = 1
ERR_PERM = 2
MaxBytes = 500000000
Source = "file"
Mode = "hex"
Text = ""
InputBytes = ""
# we try to read all bytes in a single pass
ReadMoreBytes = False
FileName = ""

def print_help():
     Help = """
SHA2 hashvalues of files or standard input
     
usage: clsha1 [OPTION] [FILE]

No FILE or "-" reads from standard input.

Options are:
     --help       prints this message
     --version    prints the version
     --base64     prints the hashvalue in base64 encoding instead of hex

Full documentation <https://senderek.ie/cryptlib/tools/clsha2>     

This program depends on two packages providing the cryptlib shared object
library and the python3-bindings to this library.

You can download both packages in RPM format at 
https://senderek.ie/cryptlib/downloads

Or in FEDORA you can install the packages cryptlib and cryptlib-python3
directly from the repository.

"""
     print( Help )


#############################################################
if len(sys.argv) > 1 :
     if sys.argv[1] == "--help":
          print_help()
          exit( OK )

     if sys.argv[1] == "--version":
          print ( Version )
          exit( OK )
     
     if sys.argv[1] == "--base64" or sys.argv[1] == "-b64" :
          Mode = "base64"
          try:
              sys.argv.remove( "-b64" )
          except:
              pass
          try:
              sys.argv.remove( "--base64" )
          except:
              pass

if len(sys.argv) > 1 :
     if sys.argv[1] == "-":
          try:
               Text = sys.stdin.read( MaxBytes )
               Source = "stdin"
               FileName = "-"
          except:
               exit ( ERR_PERM )
     elif os.path.isfile(sys.argv[1]):
          FileName = sys.argv[1]
          try:
               F = open( FileName, "rb" )
               InputBytes = F.read( MaxBytes )
          except:
               print( "cannot open file " + str(FileName) )
               exit ( ERR_PERM )
else:
     try:
          Text = sys.stdin.read( MaxBytes )
          Source = "stdin"
          FileName = "-"
     except:
          pass


##### Begin Cryptlib code #####

cryptInit()

cryptUser = CRYPT_UNUSED
hashContext_object =  cryptCreateContext( cryptUser, CRYPT_ALGO_SHA2 )
hashContext = int( hashContext_object )
Algo = bytearray( b'     ' )
namesize = cryptGetAttributeString( hashContext, CRYPT_CTXINFO_NAME_ALGO, Algo )

# hashedData must be modifiable Buffer
hashedData = bytearray()
if Text:
     hashedData.extend( Text.encode() )
else:
     hashedData.extend( InputBytes )

nullData = bytearray( b'' )

if  len(hashedData) < MaxBytes:
     # we only need one pass, no looping required
     cryptEncrypt( hashContext, hashedData )
     
else:
     # use all bytes that have been read already
     cryptEncrypt( hashContext, hashedData )
     # there are more bytes to be read
     ReadMoreBytes = True
     while ReadMoreBytes: 
          # start with empty bytearray
          del( hashedData )
          hashedData = bytearray()
          if Source == "file":
               InputBytes = F.read( MaxBytes )
               hashedData.extend( InputBytes )
               if len( InputBytes ) < MaxBytes:
                    ReadMoreBytes = False
                    # no more input
                    F.close()
          else:
               Text = sys.stdin.read( MaxBytes )
               hashedData.extend( Text.encode() )
               if len( Text ) < MaxBytes:
                    ReadMoreBytes = False
          cryptEncrypt( hashContext, hashedData )

if hashedData:     
     # end the operation with null bytes input
     if hashedData:
          cryptEncrypt( hashContext, nullData )
     else:
          exit( ERR_NOBYTES )

     # the hashvalue needs a minimum of 32 Bytes
     hashvalue = bytearray( b' '*HashSize )
     num =  cryptGetAttributeString( hashContext, CRYPT_CTXINFO_HASHVALUE, hashvalue ) 

     # output
     if num == HashSize:
          if Mode == "base64":
               print ( b64encode( hashvalue ).decode() + "  " + FileName )
          else:	  
               print( hexlify( hashvalue ).decode() + "  " + FileName )

cryptDestroyContext( hashContext )

cryptEnd()
sys.exit( OK )