Binary file to Base64 encoded MIME

Here is an inefficient implementation of a base64 encoder/decoder.
I wanted to write my own...

FUNCTION Base64Encode(InputStream AS STRING) AS STRING

LOCAL Base64Alphabet AS STRING
 Base64Alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"

LOCAL OutputStream AS STRING
 LOCAL ByteDecVal AS INTEGER
 LOCAL BitBinVal AS INTEGER
 LOCAL ByteGroup AS STRING
 LOCAL ByteGroupBinStream AS STRING
 LOCAL Padding AS STRING

LOCAL idx AS INTEGER

DO WHILE InputStream <> ""
    ByteGroup = LEFT$(InputStream, 3)
    DO WHILE ByteGroup <> ""
        FOR idx = 7 TO 0 STEP -1
            ByteDecVal = ASC(LEFT$(ByteGroup, 1))
            BitBinVal = BIT(ByteDecVal, idx)
            ByteGroupBinStream = ByteGroupBinStream & TRIM$(STR$(BitBinVal))
        NEXT idx
        ByteGroup = REMAIN$(ByteGroup, LEFT$(ByteGroup, 1))
    LOOP
    IF LEN(ByteGroupBinStream) < 24 THEN
        Padding = STRING$((((LEN(ByteGroupBinStream) / 8) -3) * -1), "=")
        ByteGroupBinStream = ByteGroupBinStream & STRING$(INT(24 / LEN(ByteGroupBinStream)) + 1, "0")
    END IF
    DO WHILE ByteGroupBinStream <> ""
        OutputStream = OutputStream & MID$(Base64Alphabet, VAL("&B00" & LEFT$(ByteGroupBinStream, 6)) + 1, 1)
        ByteGroupBinStream = REMAIN$(ByteGroupBinStream, LEFT$(ByteGroupBinStream, 6))
    LOOP
    OutputStream = OutputStream & Padding
    ByteGroupBinStream = ""
    InputStream = REMAIN$(InputStream, LEFT$(InputStream, 3))
LOOP
FUNCTION = OutputStream
END FUNCTION

FUNCTION Base64Decode(InputStream AS STRING) AS STRING
LOCAL Base64Alphabet AS STRING
 Base64Alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"

LOCAL OutputStream AS STRING
 LOCAL ByteDecVal AS INTEGER
 LOCAL BitBinVal AS INTEGER
 LOCAL ByteGroup AS STRING
 LOCAL ByteGroupBinStream AS STRING
 LOCAL Padding AS STRING

LOCAL idx AS INTEGER

Base64Alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
InputStream = REMOVE$(InputStream, ANY REMOVE$(InputStream, ANY Base64Alphabet))
DO WHILE InputStream <> ""
    ByteGroup = LEFT$(InputStream, 4)
    DO WHILE ByteGroup <> ""
        FOR idx = 5 TO 0 STEP -1
                ByteDecVal = INSTR(Base64Alphabet, LEFT$(ByteGroup, 1)) - 1
                BitBinVal = BIT(ByteDecVal, idx)
                ByteGroupBinStream = ByteGroupBinStream & TRIM$(STR$(BitBinVal))
        NEXT idx
        ByteGroup = REMAIN$(ByteGroup, LEFT$(ByteGroup, 1))
    LOOP
    DO WHILE ByteGroupBinStream <> ""
        OutputStream = OutputStream & CHR$(VAL("&B" & LEFT$(ByteGroupBinStream, 8)))
        ByteGroupBinStream = REMAIN$(ByteGroupBinStream, LEFT$(ByteGroupBinStream, 8))
    LOOP
    InputStream = REMAIN$(InputStream, LEFT$(InputStream, 4))
LOOP
FUNCTION = OutputStream

END FUNCTION

FUNCTION PBMAIN()
    STDOUT Base64Encode("ABC")
    STDOUT Base64Decode("QUJD")
END FUNCTION

------------------

[Lance Edmonds]

Search the BBS for "attachment" and you should find some clues and possibly you may find some code too.

Also, please ask your questions to the appropriate forum - the Source Code forum is not open for general discussions.

Thanks!


------------------
Lance
PowerBASIC Support
mailto:[email protected][email protected]</A>

[Guy Gyles]

Hi, I'm writing a small mail-application in PC/CC v2.00.

Everything works fine (Host, From, To, CC, Subject) but I can't combine a message with an attachment.

Separated a message works and separated a file-attached to the mail works to, but I can't let the combination work.

Anyone an idea how to do this ?

Thanks,

Guy

------------------

[Ed Turner]

I wrote the following functions a year or
so ago to encode and decode mime64. They are
included in a Terminal emulator and have
worked fine. Don't know how they will compare
to yours Dave... probably not as good but at
least everyone can get the idea of what is
involved in decoding as well as encoding.

FUNCTION mimeEncode(BYVAL strng AS STRING) AS STRING
	DIM temp?, first?, second?, third?, fourth?
	DIM Firstletter$, Secondletter$, Thirdletter$, rtn$
	rtn = nll
	n& = Len(strng)
	For i& = 1 to n& step 3
		Firstletter = Mid$(strng, i&, 1)
		If i& = n&  Then
			Secondletter = Chr$(0)
			Thirdletter = Chr$(0)
		else
			Secondletter = Mid$(strng, i& + 1, 1)
			If i& + 1 = n& Then
				Thirdletter = Chr$(0)
			Else
				Thirdletter = Mid$(strng, i& + 2, 1)
			End If
		End if
		first = ASC(Firstletter)
		SHIFT RIGHT first, 2
		second = ASC(Firstletter)
		SHIFT LEFT second, 4
		second = second AND	&H30
		temp = ASC(Secondletter)
		SHIFT RIGHT temp, 4
		second = second OR temp
		If i& = n& Then
			rtn = rtn & Nvt$(first) & Nvt$(second) & "=="
		Else
			third = ASC(Secondletter)
			SHIFT LEFT third, 2
			third = third AND &H3C
			temp = ASC(Thirdletter)
			SHIFT RIGHT temp, 6
			third = third OR temp
			If i& + 1 = n& Then
				rtn = rtn & Nvt$(first) & Nvt$(second) & Nvt$(third) & "="
			Else
				fourth = ASC(Thirdletter)
				fourth = fourth AND	&H3F
				rtn = rtn & Nvt$(first) & Nvt$(second) & Nvt$(third) & Nvt$(fourth)
			End if
		End If
	Next i&
	FUNCTION = rtn
END FUNCTION


FUNCTION ConvertToNvt(t AS Byte) As Byte
	IF t > 64 and t < 91 Then
		Function = t - 65
	Elseif t > 96 and t < 123 Then
		Function = t - 71
	Elseif t > 47 and t < 58 Then
		Function = t + 4
	Elseif t = 43 Then
		Function = 62
	Else
		Function = 63
	End If
END FUNCTION


FUNCTION mimeDecode(BYVAL strng AS STRING) AS STRING
	DIM temp?, first?, second?, third?
	DIM Firstletter$, Secondletter$, Thirdletter$, Fourthletter$, rtn$
	rtn = nll
	n& = Len(strng)
	For i& = 1 to n& step 4
		Firstletter = Mid$(strng, i&, 1)
		Secondletter = Mid$(strng, i& + 1, 1)
		Thirdletter = Mid$(strng, i& + 2, 1)
		Fourthletter = Mid$(strng, i& + 3, 1)
		first = ConvertToNvt(ASC(Firstletter))
		SHIFT LEFT first, 2
		temp = ConvertToNvt(ASC(Secondletter))
		SHIFT RIGHT temp, 4
		first = first OR temp
		If Thirdletter = "=" Then
			rtn = rtn & Chr$(first)
		Else
			second = ConvertToNvt(ASC(Secondletter))
			SHIFT LEFT second, 4
			temp = ConvertToNvt(ASC(Thirdletter))
			SHIFT RIGHT temp, 2
			second = second OR temp
			If Fourthletter = "=" Then
				rtn = rtn & Chr$(first) & Chr$(second)
			Else
				third = ConvertToNvt(ASC(Thirdletter))
				SHIFT LEFT third, 6
				temp = ConvertToNvt(ASC(Fourthletter))
				third = third OR temp
				rtn = rtn & Chr$(first) & Chr$(second) & Chr$(third)
			End If
		End If
	Next i&
	FUNCTION = rtn
END FUNCTION


SUB SetNvt()
	S$ = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
	For i& = 1 to 64
		Nvt(i& - 1) = Mid$(S$, i&, 1)
	Next i&
END SUB

By the way, you will need to set Nvt$ as
Global or else just include it in the
MimeEncode Function.
Cheers.


[This message has been edited by Ed Turner (edited 07-11-99).]

[Dave Navarro]

'----------------------------------------------------------------------------
' Convert a file to MIME text (Base64 Encoded) for PB/DLL or PB/CC
' by Dave Navarro ([email protected])
'
FUNCTION FileToMIME(InFile AS ASCIIZ, OutFile AS ASCIIZ) AS LONG
 
  LOCAL Enc     AS STRING * 64
  LOCAL b       AS ASCIIZ * 4
  LOCAL InBuff  AS STRING
  LOCAL OutBuff AS STRING
  LOCAL i       AS LONG
 
  Enc = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
 
  OPEN InFile FOR BINARY AS #1
  OPEN OutFile FOR OUTPUT AS #2
 
    PRINT# 2, "MIME-Version: 1.0"
    PRINT# 2, "Content-Type: application/octet-stream; name=" + InFile
    PRINT# 2, "Content-transfer-encoding: base64"
    PRINT# 2, ""
 
    WHILE NOT EOF(1)
      GET$ 1, 57, InBuff
      OutBuff = ""
      WHILE LEN(InBuff)
        b = LEFT$(InBuff, 3)
        ! mov AL, b[0]
        ! shr AL, 2
        ! movzx i, AL
        OutBuff = OutBuff + MID$(Enc, i+1, 1)
        ! mov AL, b[1]
        ! mov AH, b[0]
        ! shr AX, 4
        ! and AL, &H3F
        ! movzx i, AL
        OutBuff = OutBuff + MID$(Enc, i+1, 1)
        IF LEN(InBuff) = 1 THEN
          OutBuff = OutBuff + "=="
          EXIT DO
        END IF
        ! mov AL, b[2]
        ! mov AH, b[1]
        ! shr AX, 6
        ! and AL, &H3F
        ! movzx i, AL
        OutBuff = OutBuff + MID$(Enc, i+1, 1)
        IF LEN(InBuff) = 2 THEN
          OutBuff = OutBuff + "="
          EXIT DO
        END IF
        ! mov AL, b[2]
        ! and AL, &H3F
        ! movzx i, AL
        OutBuff = OutBuff + MID$(Enc, i+1, 1)
        InBuff = MID$(InBuff, 4)
      WEND
      PRINT#2, OutBuff
    WEND
  CLOSE
 
END FUNCTION