base64.pas

base64编码算法 base64编码算法

unit Base64;

interface

uses Classes;

function  MimeEncodeString (const s: AnsiString): AnsiString;
function  MimeEncodeStringNoCRLF (const s: AnsiString): AnsiString;
function  MimeDecodeString (const s: AnsiString): AnsiString;
procedure MimeEncodeStream (const InputStream: TStream; const OutputStream: TStream);
procedure MimeEncodeStreamNoCRLF (const InputStream: TStream; const OutputStream: TStream);
procedure MimeDecodeStream (const InputStream: TStream; const OutputStream: TStream);
function  MimeEncodedSize (const i: Cardinal): Cardinal;
function  MimeEncodedSizeNoCRLF (const i: Cardinal): Cardinal;
function  MimeDecodedSize (const i: Cardinal): Cardinal;
procedure DecodeHttpBasicAuthentication (const BasicCredentials: AnsiString; out UserId, PassWord: AnsiString);
procedure MimeEncode (const InputBuffer; const InputByteCount: Cardinal; out OutputBuffer);
procedure MimeEncodeNoCRLF (const InputBuffer; const InputByteCount: Cardinal; out OutputBuffer);
procedure MimeEncodeFullLines (const InputBuffer; const InputByteCount: Cardinal; out OutputBuffer);
function  MimeDecode (const InputBuffer; const InputBytesCount: Cardinal; out OutputBuffer): Cardinal;
function  MimeDecodePartial (const InputBuffer; const InputBytesCount: Cardinal;
  out OutputBuffer; var ByteBuffer: Cardinal; var ByteBufferSpace: Cardinal): Cardinal;
function  MimeDecodePartialEnd (out OutputBuffer; const ByteBuffer: Cardinal;
  const ByteBufferSpace: Cardinal): Cardinal;
procedure Base64Encode(InputFile, OutputFile: string);
procedure Base64Decode(InputFile, OutputFile: string);

const
 MIME_ENCODED_LINE_BREAK = 76;
 MIME_DECODED_LINE_BREAK = MIME_ENCODED_LINE_BREAK div 4 * 3;
 BUFFER_SIZE        = MIME_DECODED_LINE_BREAK * 3 * 4 * 16;
 MIME_ENCODE_TABLE  : array[0..63] of Byte = (
  065, 066, 067, 068, 069, 070, 071, 072, // 00 - 07
  073, 074, 075, 076, 077, 078, 079, 080, // 08 - 15
  081, 082, 083, 084, 085, 086, 087, 088, // 16 - 23
  089, 090, 097, 098, 099, 100, 101, 102, // 24 - 31
  103, 104, 105, 106, 107, 108, 109, 110, // 32 - 39
  111, 112, 113, 114, 115, 116, 117, 118, // 40 - 47
  119, 120, 121, 122, 048, 049, 050, 051, // 48 - 55
  052, 053, 054, 055, 056, 057, 043, 047); // 56 - 63

 MIME_PAD_CHAR      = Byte ('=');

 MIME_DECODE_TABLE  : array[Byte] of Cardinal = (
  255, 255, 255, 255, 255, 255, 255, 255, //  00 -  07
  255, 255, 255, 255, 255, 255, 255, 255, //  08 -  15
  255, 255, 255, 255, 255, 255, 255, 255, //  16 -  23
  255, 255, 255, 255, 255, 255, 255, 255, //  24 -  31
  255, 255, 255, 255, 255, 255, 255, 255, //  32 -  39
  255, 255, 255, 062, 255, 255, 255, 063, //  40 -  47
  052, 053, 054, 055, 056, 057, 058, 059, //  48 -  55
  060, 061, 255, 255, 255, 255, 255, 255, //  56 -  63
  255, 000, 001, 002, 003, 004, 005, 006, //  64 -  71
  007, 008, 009, 010, 011, 012, 013, 014, //  72 -  79
  015, 016, 017, 018, 019, 020, 021, 022, //  80 -  87
  023, 024, 025, 255, 255, 255, 255, 255, //  88 -  95
  255, 026, 027, 028, 029, 030, 031, 032, //  96 - 103
  033, 034, 035, 036, 037, 038, 039, 040, // 104 - 111
  041, 042, 043, 044, 045, 046, 047, 048, // 112 - 119
  049, 050, 051, 255, 255, 255, 255, 255, // 120 - 127
  255, 255, 255, 255, 255, 255, 255, 255,
  255, 255, 255, 255, 255, 255, 255, 255,
  255, 255, 255, 255, 255, 255, 255, 255,
  255, 255, 255, 255, 255, 255, 255, 255,
  255, 255, 255, 255, 255, 255, 255, 255,
  255, 255, 255, 255, 255, 255, 255, 255,
  255, 255, 255, 255, 255, 255, 255, 255,
  255, 255, 255, 255, 255, 255, 255, 255,
  255, 255, 255, 255, 255, 255, 255, 255,
  255, 255, 255, 255, 255, 255, 255, 255,
  255, 255, 255, 255, 255, 255, 255, 255,
  255, 255, 255, 255, 255, 255, 255, 255,
  255, 255, 255, 255, 255, 255, 255, 255,
  255, 255, 255, 255, 255, 255, 255, 255,
  255, 255, 255, 255, 255, 255, 255, 255,
  255, 255, 255, 255, 255, 255, 255, 255);

type
 PByte4 = ^TByte4;
 TByte4 = packed record
  b1: Byte;
  b2: Byte;
  b3: Byte;
  b4: Byte;
 end;

 PByte3 = ^TByte3;
 TByte3 = packed record
  b1: Byte;
  b2: Byte;
  b3: Byte;
 end;

implementation


function MimeEncodeString (const s: AnsiString): AnsiString;
var
 l                  : Cardinal;
begin
 if Pointer (s) <> nil then
  begin
   l := Cardinal (Pointer (Cardinal (s) - 4)^);
   SetLength (Result, MimeEncodedSize (l));
   MimeEncode (Pointer (s)^, l, Pointer (Result)^);
  end
 else
  Result := '';
end;

function MimeEncodeStringNoCRLF (const s: AnsiString): AnsiString;
var
 l                  : Cardinal;
begin
 if Pointer (s) <> nil then
  begin
   l := Cardinal (Pointer (Cardinal (s) - 4)^);
   SetLength (Result, MimeEncodedSizeNoCRLF (l));
   MimeEncodeNoCRLF (Pointer (s)^, l, Pointer (Result)^);
  end
 else
  Result := '';
end;

function MimeDecodeString (const s: AnsiString): AnsiString;
var
 ByteBuffer, ByteBufferSpace: Cardinal;
 l                  : Cardinal;
begin
 if Pointer (s) <> nil then
  begin
   l := Cardinal (Pointer (Cardinal (s) - 4)^);
   SetLength (Result, (l + 3) div 4 * 3);
   ByteBuffer := 0;
   ByteBufferSpace := 4;
   l := MimeDecodePartial (Pointer (s)^, l, Pointer (Result)^, ByteBuffer, ByteBufferSpace);
   Inc (l, MimeDecodePartialEnd (Pointer (Cardinal (Result) + l)^,
     ByteBuffer, ByteBufferSpace));
   SetLength (Result, l);
  end
 else
  Result := '';
end;

procedure MimeEncodeStream (const InputStream: TStream; const OutputStream: TStream);
var
 InputBuffer : array[0..BUFFER_SIZE - 1] of Byte;
 OutputBuffer : array[0.. (BUFFER_SIZE + 2) div 3 * 4 + BUFFER_SIZE div 
   MIME_DECODED_LINE_BREAK * 2 - 1] of Byte;
 BytesRead : Cardinal;
 IDelta, ODelta : Cardinal;
begin
 BytesRead := InputStream.Read (InputBuffer, SizeOf (InputBuffer));
 
 while BytesRead = SizeOf (InputBuffer) do
  begin
   MimeEncodeFullLines (InputBuffer, SizeOf (InputBuffer), OutputBuffer);
   OutputStream.Write (OutputBuffer, SizeOf (OutputBuffer));
   BytesRead := InputStream.Read (InputBuffer, SizeOf (InputBuffer));
  end;

 MimeEncodeFullLines (InputBuffer, BytesRead, OutputBuffer);
 
 IDelta := BytesRead div MIME_DECODED_LINE_BREAK; // Number of lines processed.
 ODelta := IDelta * (MIME_ENCODED_LINE_BREAK + 2);
 IDelta := IDelta * MIME_DECODED_LINE_BREAK;
 MimeEncodeNoCRLF(Pointer(Cardinal (@InputBuffer) + IDelta)^, BytesRead - IDelta, 
   Pointer (Cardinal (@OutputBuffer) + ODelta)^);
 
 OutputStream.Write (OutputBuffer, MimeEncodedSize (BytesRead));
end;

procedure MimeEncodeStreamNoCRLF (const InputStream: TStream; const OutputStream: TStream);
var
 InputBuffer        : array[0..BUFFER_SIZE - 1] of Byte;
 OutputBuffer       : array[0.. ((BUFFER_SIZE + 2) div 3) * 4 - 1] of Byte;
 BytesRead          : Cardinal;
begin
 BytesRead := InputStream.Read (InputBuffer, SizeOf (InputBuffer));
 while BytesRead = SizeOf (InputBuffer) do
  begin
   MimeEncodeNoCRLF (InputBuffer, SizeOf (InputBuffer), OutputBuffer);
   OutputStream.Write (OutputBuffer, SizeOf (OutputBuffer));
   BytesRead := InputStream.Read (InputBuffer, SizeOf (InputBuffer));
  end;

 MimeEncodeNoCRLF (InputBuffer, BytesRead, OutputBuffer);
 OutputStream.Write (OutputBuffer, (BytesRead + 2) div 3 * 4);
end;

procedure MimeDecodeStream (const InputStream: TStream; const OutputStream: TStream);
var
 ByteBuffer, ByteBufferSpace: Cardinal;
 InputBuffer        : array[0..BUFFER_SIZE - 1] of Byte;
 OutputBuffer       : array[0.. (BUFFER_SIZE + 3) div 4 * 3 - 1] of Byte;
 BytesRead          : Cardinal;
begin
 ByteBuffer := 0;
 ByteBufferSpace := 4;
 BytesRead := InputStream.Read (InputBuffer, SizeOf (InputBuffer));
 while BytesRead > 0 do
  begin
   OutputStream.Write(OutputBuffer, MimeDecodePartial(InputBuffer, BytesRead, 
     OutputBuffer, ByteBuffer, ByteBufferSpace));
   BytesRead := InputStream.Read (InputBuffer, SizeOf (InputBuffer));
  end;
 OutputStream.Write (OutputBuffer, MimeDecodePartialEnd (OutputBuffer, ByteBuffer, 
   ByteBufferSpace));
end;

procedure DecodeHttpBasicAuthentication (const BasicCredentials: AnsiString; out UserId, PassWord: AnsiString);
label
 Fail;
const
 LBasic = 6;                { Length ('Basic ') }
var
 DecodedPtr, p      : PAnsiChar;
 i, l               : Cardinal;
begin
 p := Pointer (BasicCredentials);
 if p = nil then goto Fail;
 
 l := Cardinal (Pointer (p - 4)^);
 if l <= LBasic then goto Fail;
 
 Dec (l, LBasic);
 Inc (p, LBasic);
 
 GetMem (DecodedPtr, (l + 3) div 4 * 3 { MimeDecodedSize (l) });
 l := MimeDecode (p^, l, DecodedPtr^);
 i := 0;
 p := DecodedPtr;
 while (l > 0) and (p[i] <> ':') do
  begin
   Inc (i);
   Dec (l);
  end;
 SetString (UserId, DecodedPtr, i);
 if l > 1 then
  SetString (PassWord, DecodedPtr + i + 1, l - 1)
 else
  PassWord := '';
 
 FreeMem (DecodedPtr);
 Exit;
 
 Fail:
 UserId := '';
 PassWord := '';
end;

function MimeEncodedSize (const i: Cardinal): Cardinal;
begin
 Result := (i + 2) div 3 * 4 + (i - 1) div MIME_DECODED_LINE_BREAK * 2;
end;

function MimeEncodedSizeNoCRLF (const i: Cardinal): Cardinal;
begin
 Result := (i + 2) div 3 * 4;
end;