!--------------------------------------------------------------------------------------------------
!> @author Martin Diehl, Max-Planck-Institut für Eisenforschung GmbH
!> @brief Decode Base64 strings.
!> @details See https://en.wikipedia.org/wiki/Base64.
!--------------------------------------------------------------------------------------------------
module base64
use prec
use IO
implicit none
private
character(len=*), parameter :: &
base64_encoding='ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'
public :: &
base64_init, &
base64_to_bytes, &
base64_nChar, &
base64_nByte
contains
!--------------------------------------------------------------------------------------------------
!> @brief Do self test.
!--------------------------------------------------------------------------------------------------
subroutine base64_init
print'(/,a)', ' <<<+- base64 init -+>>>'; flush(OUTPUT_UNIT)
call selfTest
end subroutine base64_init
!--------------------------------------------------------------------------------------------------
!> @brief Calculate number of Base64 characters required for storage of N bytes.
!--------------------------------------------------------------------------------------------------
pure function base64_nChar(nByte)
integer(pI64), intent(in) :: nByte
integer(pI64) :: base64_nChar
base64_nChar = 4_pI64 * (nByte/3_pI64 + merge(1_pI64,0_pI64,mod(nByte,3_pI64) /= 0_pI64))
end function base64_nChar
!--------------------------------------------------------------------------------------------------
!> @brief Calculate number of bytes required for storage of N Base64 characters.
!--------------------------------------------------------------------------------------------------
pure function base64_nByte(nBase64)
integer(pI64), intent(in) :: nBase64
integer(pI64) :: base64_nByte
base64_nByte = 3_pI64 * (nBase64/4_pI64)
end function base64_nByte
!--------------------------------------------------------------------------------------------------
!> @brief Decode Base64 ASCII string into byte-wise binary representation.
!--------------------------------------------------------------------------------------------------
function base64_to_bytes(base64_str,s,e) result(bytes)
character(len=*), intent(in) :: base64_str !< Base64 string representation
integer(pI64), intent(in), optional :: &
s, & !< start (in bytes)
e !< end (in bytes)
integer(pI64) :: s_bytes, e_bytes, s_str, e_str
integer(C_SIGNED_CHAR), dimension(:), allocatable :: bytes
if(.not. validBase64(base64_str)) call IO_error(114,ext_msg='invalid character')
if(present(s)) then
if(s<1_pI64) call IO_error(114, ext_msg='s out of range')
s_str = ((s-1_pI64)/3_pI64)*4_pI64 + 1_pI64
s_bytes = mod(s-1_pI64,3_pI64) + 1_pI64
else
s_str = 1_pI64
s_bytes = 1_pI64
endif
if(present(e)) then
if(e>base64_nByte(len(base64_str,kind=pI64))) call IO_error(114, ext_msg='e out of range')
e_str = ((e-1_pI64)/3_pI64)*4_pI64 + 4_pI64
e_bytes = e - base64_nByte(s_str)
else
e_str = len(base64_str,kind=pI64)
e_bytes = base64_nByte(len(base64_str,kind=pI64)) - base64_nByte(s_str)
if(base64_str(e_str-0_pI64:e_str-0_pI64) == '=') e_bytes = e_bytes - 1_pI64
if(base64_str(e_str-1_pI64:e_str-1_pI64) == '=') e_bytes = e_bytes - 1_pI64
endif
bytes = decodeBase64(base64_str(s_str:e_str))
bytes = bytes(s_bytes:e_bytes)
end function base64_to_bytes
!--------------------------------------------------------------------------------------------------
!> @brief Convert a Base64 ASCII string into its byte-wise binary representation.
!--------------------------------------------------------------------------------------------------
pure function decodeBase64(base64_str) result(bytes)
character(len=*), intent(in) :: base64_str !< Base64 string representation
integer(C_SIGNED_CHAR), dimension(base64_nByte(len(base64_str,pI64))) :: bytes
integer(C_SIGNED_CHAR), dimension(0:3) :: charPos
integer(pI64) :: c, b, p
c = 1_pI64
b = 1_pI64
do while(c < len(base64_str,kind=pI64))
do p=0_pI64,3_pI64
if(c+p<=len(base64_str,kind=pI64)) then
charPos(p) = int(index(base64_encoding,base64_str(c+p:c+p))-1,C_SIGNED_CHAR)
else
charPos(p) = 0_C_SIGNED_CHAR
endif
enddo
call mvbits(charPos(0),0,6,bytes(b+0),2)
call mvbits(charPos(1),4,2,bytes(b+0),0)
call mvbits(charPos(1),0,4,bytes(b+1),4)
call mvbits(charPos(2),2,4,bytes(b+1),0)
call mvbits(charPos(2),0,2,bytes(b+2),6)
call mvbits(charPos(3),0,6,bytes(b+2),0)
b = b+3_pI64
c = c+4_pI64
enddo
end function decodeBase64
!--------------------------------------------------------------------------------------------------
!> @brief Test for valid Base64 encoded string.
!> @details Input string must be properly padded.
!--------------------------------------------------------------------------------------------------
pure logical function validBase64(base64_str)
character(len=*), intent(in) :: base64_str !< Base64 string representation
integer(pI64) :: l
l = len(base64_str,pI64)
validBase64 = .true.
if(mod(l,4_pI64)/=0_pI64 .or. l < 4_pInt) validBase64 = .false.
if(verify(base64_str(:l-2_pI64),base64_encoding, kind=pI64) /= 0_pI64) validBase64 = .false.
if(verify(base64_str(l-1_pI64:),base64_encoding//'=',kind=pI64) /= 0_pI64) validBase64 = .false.
end function validBase64
!--------------------------------------------------------------------------------------------------
!> @brief Check correctness of base64 functions.
!--------------------------------------------------------------------------------------------------
subroutine selfTest
integer(C_SIGNED_CHAR), dimension(:), allocatable :: bytes
character(len=*), parameter :: zero_to_three = 'AAECAw=='
! https://en.wikipedia.org/wiki/Base64#Output_padding
if(base64_nChar(20_pI64) /= 28_pI64) error stop 'base64_nChar/20/28'
if(base64_nChar(19_pI64) /= 28_pI64) error stop 'base64_nChar/19/28'
if(base64_nChar(18_pI64) /= 24_pI64) error stop 'base64_nChar/18/24'
if(base64_nChar(17_pI64) /= 24_pI64) error stop 'base64_nChar/17/24'
if(base64_nChar(16_pI64) /= 24_pI64) error stop 'base64_nChar/16/24'
if(base64_nByte(4_pI64) /= 3_pI64) error stop 'base64_nByte/4/3'
if(base64_nByte(8_pI64) /= 6_pI64) error stop 'base64_nByte/8/6'
bytes = base64_to_bytes(zero_to_three)
if(any(bytes /= int([0,1,2,3],C_SIGNED_CHAR)) .or. size(bytes) /= 4) error stop 'base64_to_bytes//'
bytes = base64_to_bytes(zero_to_three,e=1_pI64)
if(any(bytes /= int([0],C_SIGNED_CHAR)) .or. size(bytes) /= 1) error stop 'base64_to_bytes//1'
bytes = base64_to_bytes(zero_to_three,e=2_pI64)
if(any(bytes /= int([0,1],C_SIGNED_CHAR)) .or. size(bytes) /= 2) error stop 'base64_to_bytes//2'
bytes = base64_to_bytes(zero_to_three,e=3_pI64)
if(any(bytes /= int([0,1,2],C_SIGNED_CHAR)) .or. size(bytes) /= 3) error stop 'base64_to_bytes//3'
bytes = base64_to_bytes(zero_to_three,e=4_pI64)
if(any(bytes /= int([0,1,2,3],C_SIGNED_CHAR)) .or. size(bytes) /= 4) error stop 'base64_to_bytes//4'
bytes = base64_to_bytes(zero_to_three,s=1_pI64)
if(any(bytes /= int([0,1,2,3],C_SIGNED_CHAR)) .or. size(bytes) /= 4) error stop 'base64_to_bytes/1/'
bytes = base64_to_bytes(zero_to_three,s=2_pI64)
if(any(bytes /= int([1,2,3],C_SIGNED_CHAR)) .or. size(bytes) /= 3) error stop 'base64_to_bytes/2/'
bytes = base64_to_bytes(zero_to_three,s=3_pI64)
if(any(bytes /= int([2,3],C_SIGNED_CHAR)) .or. size(bytes) /= 2) error stop 'base64_to_bytes/3/'
bytes = base64_to_bytes(zero_to_three,s=4_pI64)
if(any(bytes /= int([3],C_SIGNED_CHAR)) .or. size(bytes) /= 1) error stop 'base64_to_bytes/4/'
bytes = base64_to_bytes(zero_to_three,s=1_pI64,e=1_pI64)
if(any(bytes /= int([0],C_SIGNED_CHAR)) .or. size(bytes) /= 1) error stop 'base64_to_bytes/1/1'
bytes = base64_to_bytes(zero_to_three,s=2_pI64,e=2_pI64)
if(any(bytes /= int([1],C_SIGNED_CHAR)) .or. size(bytes) /= 1) error stop 'base64_to_bytes/2/2'
bytes = base64_to_bytes(zero_to_three,s=3_pI64,e=3_pI64)
if(any(bytes /= int([2],C_SIGNED_CHAR)) .or. size(bytes) /= 1) error stop 'base64_to_bytes/3/3'
bytes = base64_to_bytes(zero_to_three,s=4_pI64,e=4_pI64)
if(any(bytes /= int([3],C_SIGNED_CHAR)) .or. size(bytes) /= 1) error stop 'base64_to_bytes/4/4'
bytes = base64_to_bytes(zero_to_three,s=1_pI64,e=2_pI64)
if(any(bytes /= int([0,1],C_SIGNED_CHAR)) .or. size(bytes) /= 2) error stop 'base64_to_bytes/1/2'
bytes = base64_to_bytes(zero_to_three,s=2_pI64,e=3_pI64)
if(any(bytes /= int([1,2],C_SIGNED_CHAR)) .or. size(bytes) /= 2) error stop 'base64_to_bytes/2/3'
bytes = base64_to_bytes(zero_to_three,s=3_pI64,e=4_pI64)
if(any(bytes /= int([2,3],C_SIGNED_CHAR)) .or. size(bytes) /= 2) error stop 'base64_to_bytes/3/4'
bytes = base64_to_bytes(zero_to_three,s=1_pI64,e=3_pI64)
if(any(bytes /= int([0,1,2],C_SIGNED_CHAR)) .or. size(bytes) /= 3) error stop 'base64_to_bytes/1/3'
bytes = base64_to_bytes(zero_to_three,s=2_pI64,e=4_pI64)
if(any(bytes /= int([1,2,3],C_SIGNED_CHAR)) .or. size(bytes) /= 3) error stop 'base64_to_bytes/2/4'
bytes = base64_to_bytes(zero_to_three,s=1_pI64,e=4_pI64)
if(any(bytes /= int([0,1,2,3],C_SIGNED_CHAR)) .or. size(bytes) /= 4) error stop 'base64_to_bytes/1/4'
end subroutine selfTest
end module base64