!-------------------------------------------------------------------------------------------------- !> @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'(/,1x,a)', '<<<+- base64 init -+>>>'; flush(IO_STDOUT) 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_pI64) 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