simplified base64 encoding
- ensure valid Base64 string (needs to be padded correctly) - background routine expects proper Base64 string (length = N*4) - user routine ensures correct length of byte representation
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Martin Diehl
parent
049ad4e202
commit
a70819e458
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@ -1,6 +1,7 @@
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!--------------------------------------------------------------------------------------------------
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!> @author Martin Diehl, Max-Planck-Institut für Eisenforschung GmbH
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!> @brief Decode Base64 strings
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!> @brief Decode Base64 strings.
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!> @details See https://en.wikipedia.org/wiki/Base64.
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!--------------------------------------------------------------------------------------------------
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module base64
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use prec
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@ -9,6 +10,9 @@ module base64
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implicit none
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private
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character(len=*), parameter :: &
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base64_encoding='ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'
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public :: &
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base64_init, &
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base64_to_bytes, &
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@ -19,7 +23,7 @@ contains
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!--------------------------------------------------------------------------------------------------
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!> @brief do self test
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!> @brief Do self test.
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!--------------------------------------------------------------------------------------------------
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subroutine base64_init
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@ -31,7 +35,7 @@ end subroutine base64_init
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!--------------------------------------------------------------------------------------------------
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!> @brief calculate number of Base64 characters required for storage of N bytes
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!> @brief Calculate number of Base64 characters required for storage of N bytes.
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!--------------------------------------------------------------------------------------------------
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pure function base64_nBase64(nByte)
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@ -44,7 +48,7 @@ end function base64_nBase64
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!--------------------------------------------------------------------------------------------------
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!> @brief calculate number of bytes required for storage of N Base64 characters
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!> @brief Calculate number of bytes required for storage of N Base64 characters.
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!--------------------------------------------------------------------------------------------------
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pure function base64_nByte(nBase64)
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@ -57,61 +61,64 @@ end function base64_nByte
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!--------------------------------------------------------------------------------------------------
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!> @brief return byte-wise binary representation of a (part of a) Base64 ASCII string
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!> @brief Decode Base64 ASCII string into byte-wise binary representation.
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!--------------------------------------------------------------------------------------------------
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pure function base64_to_bytes(base64_str,s,e) result(bytes)
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function base64_to_bytes(base64_str,s,e) result(bytes)
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character(len=*), intent(in) :: base64_str !< Base64 string representation
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integer(pLongInt), intent(in), optional :: &
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s, & !< start (in bytes)
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e !< end (in bytes)
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integer(pLongInt) :: s_, e_
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integer(pLongInt) :: s_bytes, e_bytes
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integer(C_SIGNED_CHAR), dimension(:), allocatable :: bytes, bytes_raw
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allocate(bytes_raw(base64_nByte(len_trim(base64_str,pLongInt))))
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if(.not. valid_base64(base64_str)) error stop 'invalid base64'
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if(present(s)) then
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s_ = s
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if(s<1_pLongInt) error stop 'invalid s'
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s_bytes = s
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else
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s_ = 1
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s_bytes = 1
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endif
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if(present(e)) then
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e_ = e
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if(e>base64_nByte(len(base64_str,kind=pLongInt))) error stop 'invalid e'
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e_bytes = e
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else
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e_ = size(bytes_raw,kind=pLongInt)
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e_bytes = base64_nByte(len(base64_str,kind=pLongInt))
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if(base64_str(len(base64_str)-0_pLongInt:len(base64_str)-0_pLongInt) == '=') &
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e_bytes = e_bytes -1_pLongInt
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if(base64_str(len(base64_str)-1_pLongInt:len(base64_str)-1_pLongInt) == '=') &
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e_bytes = e_bytes -1_pLongInt
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endif
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! ToDo: inefficient for s_>>1 or e_<<size(bytes_raw)
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bytes_raw = decode_base64(base64_str)
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bytes = bytes_raw(s_:e_)
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bytes = bytes_raw(s_bytes:e_bytes)
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end function base64_to_bytes
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!--------------------------------------------------------------------------------------------------
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!> @brief convert a Base64 ASCII string into its byte-wise binary representation
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!> @details see https://en.wikipedia.org/wiki/Base64. Input string must be properly padded.
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!> @brief Convert a Base64 ASCII string into its byte-wise binary representation.
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!--------------------------------------------------------------------------------------------------
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pure function decode_base64(base64_str) result(bytes)
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character(len=*), intent(in) :: base64_str !< Base64 string representation
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integer(C_SIGNED_CHAR), dimension(base64_nByte(len_trim(base64_str,pLongInt))) :: bytes
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integer(C_SIGNED_CHAR), dimension(base64_nByte(len(base64_str,pLongInt))) :: bytes
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integer(C_SIGNED_CHAR), dimension(0:3) :: charPos
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integer(pLongInt) :: c, b, p
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character(len=*), parameter :: encoding='ABCDEFGHIJKLMNOPQRSTUVWXYZ&
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&abcdefghijklmnopqrstuvwxyz0123456789+/'
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c = 1_pLongInt
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b = 1_pLongInt
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do while(c + 3_pInt <= len_trim(base64_str,kind=pLongInt)) !ToDo: Confusing + 3
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do while(c < len(base64_str,kind=pLongInt))
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do p=0_pLongInt,3_pLongInt
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if(c+p<=len(base64_str,kind=pLongInt)) then
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charPos(p) = int(merge(index(encoding,base64_str(c+p:c+p))-1, 0, base64_str(c+p:c+p) /= '='),C_SIGNED_CHAR)
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charPos(p) = int(index(base64_encoding,base64_str(c+p:c+p))-1,C_SIGNED_CHAR)
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else
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charPos(p) = 0_C_SIGNED_CHAR
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endif
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@ -131,7 +138,27 @@ end function decode_base64
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!--------------------------------------------------------------------------------------------------
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!> @brief check correctness of base64 functions
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!> @brief Test for valid Base64 encoded string.
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!> @details Input string must be properly padded.
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!--------------------------------------------------------------------------------------------------
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pure logical function valid_base64(base64_str)
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character(len=*), intent(in) :: base64_str !< Base64 string representation
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integer(pLongInt) :: l
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l = len(base64_str,pLongInt)
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valid_base64 = .true.
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if(mod(l,4_pLongInt)/=0_pLongInt .or. l < 4_pInt) valid_base64 = .false.
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if(verify(base64_str(:l-2_pLongInt),base64_encoding, kind=pLongInt) /= 0_pLongInt) valid_base64 = .false.
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if(verify(base64_str(l-1_pLongInt:),base64_encoding//'=',kind=pLongInt) /= 0_pLongInt) valid_base64 = .false.
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end function valid_base64
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!--------------------------------------------------------------------------------------------------
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!> @brief Check correctness of base64 functions.
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!--------------------------------------------------------------------------------------------------
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subroutine selfTest
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@ -139,10 +166,10 @@ subroutine selfTest
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character(len=*), parameter :: zero_to_three = 'AAECAw=='
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bytes = base64_to_bytes(zero_to_three)
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if(any(bytes /= int([0,1,2,3,0,0],C_SIGNED_CHAR)) .or. size(bytes) /= 6) call IO_error(0,ext_msg='base64_to_bytes')
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if(any(bytes /= int([0,1,2,3],C_SIGNED_CHAR)) .or. size(bytes) /= 4) call IO_error(0,ext_msg='base64_to_bytes')
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bytes = base64_to_bytes(zero_to_three,s=2_pLongInt)
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if(any(bytes /= int([1,2,3,0,0],C_SIGNED_CHAR)) .or. size(bytes) /= 5) call IO_error(0,ext_msg='base64_to_bytes/s')
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if(any(bytes /= int([1,2,3],C_SIGNED_CHAR)) .or. size(bytes) /= 3) call IO_error(0,ext_msg='base64_to_bytes/s')
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bytes = base64_to_bytes(zero_to_three,s=2_pLongInt,e=3_pLongInt)
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if(any(bytes /= int([1,2],C_SIGNED_CHAR)) .or. size(bytes) /= 2) call IO_error(0,ext_msg='base64_to_bytes/s/e')
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