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* Patch from Bram Kuijvenhoven to fix stream, and add MIME mode

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git-svn-id: trunk@6987 -
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michael 2007-03-24 22:46:33 +00:00
parent 74cbe82e3f
commit 28e7b354cc
1 changed files with 226 additions and 95 deletions
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321
packages/fcl-base/src/inc/base64.pp
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@ -12,7 +12,12 @@
**********************************************************************}
// Encoding and decoding streams for base64 data as described in RFC2045
// Encoding and decoding streams for base64 data as described in
// RFC2045 (Mode = bdmMIME) and
// RFC3548 (Mode = bdmStrict)
// Addition of TBase64DecodingMode supporting both Strict and MIME mode is
// (C) 2007 Hexis BV, by Bram Kuijvenhoven (bkuijvenhoven@hexis.nl)
{$MODE objfpc}
{$H+}
@ -21,7 +26,7 @@ unit base64;
interface
uses classes;
uses classes, sysutils;
type
@ -40,51 +45,88 @@ type
function Seek(Offset: Longint; Origin: Word): Longint; override;
end;
(* The TBase64DecodingStream supports two modes:
* - 'strict mode':
* - follows RFC3548
* - rejects any characters outside of base64 alphabet,
* - only accepts up to two '=' characters at the end and
* - requires the input to have a Size being a multiple of 4; otherwise raises an EBase64DecodeException
* - 'MIME mode':
* - follows RFC2045
* - ignores any characters outside of base64 alphabet
* - takes any '=' as end of string
* - handles apparently truncated input streams gracefully
*)
TBase64DecodingMode = (bdmStrict, bdmMIME);
{ TBase64DecodingStream }
TBase64DecodingStream = class(TStream)
private
FMode: TBase64DecodingMode;
procedure SetMode(const AValue: TBase64DecodingMode);
function GetSize: Int64; override;
function GetPosition: Int64; override;
protected
InputStream: TStream;
CurPos, InputStreamSize: LongInt;
Buf: array[0..2] of Byte;
BufPos: Integer; // Offset of byte which is to be read next
fEOF: Boolean;
CurPos, // 0-based (decoded) position of this stream (nr. of decoded & Read bytes since last reset)
DecodedSize: Int64; // length of decoded stream ((expected) decoded bytes since last Reset until Mode-dependent end of stream)
ReadBase64ByteCount: Int64; // number of valid base64 bytes read from input stream since last Reset
Buf: array[0..2] of Byte; // last 3 decoded bytes
BufPos: Integer; // offset in Buf of byte which is to be read next; if >2, next block must be read from InputStream & decoded
FEOF: Boolean; // if true, all decoded bytes have been read
public
constructor Create(AInputStream: TStream);
constructor Create(AInputStream: TStream; AMode: TBase64DecodingMode);
procedure Reset;
function Read(var Buffer; Count: Longint): Longint; override;
function Write(const Buffer; Count: Longint): Longint; override;
function Seek(Offset: Longint; Origin: Word): Longint; override;
property EOF: Boolean read fEOF;
property Mode: TBase64DecodingMode read FMode write SetMode;
end;
EBase64DecodingException = class(Exception)
end;
implementation
uses
Math;
const
SStrictNonBase64Char = 'Non-valid Base64 Encoding character in input';
SStrictInputTruncated = 'Input stream was truncated at non-4 byte boundary';
SStrictMisplacedPadChar = 'Unexpected padding character ''='' before end of input stream';
EncodingTable: PChar =
'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';
DecTable: array[Byte] of Byte =
(99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, // 0-15
99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, // 16-31
99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 62, 99, 99, 99, 63, // 32-47
52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 99, 99, 99, 00, 99, 99, // 48-63
99, 00, 01, 02, 03, 04, 05, 06, 07, 08, 09, 10, 11, 12, 13, 14, // 64-79
15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 99, 99, 99, 99, 99, // 80-95
99, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, // 96-111
41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 99, 99, 99, 99, 99, // 112-127
99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99,
99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99,
99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99,
99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99,
99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99,
99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99,
99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99,
99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99);
const
NA = 85; // not in base64 alphabet at all; binary: 01010101
PC = 255; // padding character 11111111
DecTable: array[Byte] of Byte =
(NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, // 0-15
NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, // 16-31
NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, 62, NA, NA, NA, 63, // 32-47
52, 53, 54, 55, 56, 57, 58, 59, 60, 61, NA, NA, NA, PC, NA, NA, // 48-63
NA, 00, 01, 02, 03, 04, 05, 06, 07, 08, 09, 10, 11, 12, 13, 14, // 64-79
15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, NA, NA, NA, NA, NA, // 80-95
NA, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, // 96-111
41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, NA, NA, NA, NA, NA, // 112-127
NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA,
NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA,
NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA,
NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA,
NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA,
NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA,
NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA,
NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA);
Alphabet = ['a'..'z','A'..'Z','0'..'9','+','/','=']; // all 65 chars that are in the base64 encoding alphabet
constructor TBase64EncodingStream.Create(AOutputStream: TStream);
begin
@ -164,96 +206,211 @@ begin
raise EStreamError.Create('Invalid stream operation');
end;
procedure TBase64DecodingStream.SetMode(const AValue: TBase64DecodingMode);
begin
if FMode = AValue then exit;
FMode := AValue;
DecodedSize := -1; // forget any calculations on this
end;
function TBase64DecodingStream.GetSize: Int64;
var
endBytes: array[0..1] of Char;
ipos, isize: Int64;
scanBuf: array[0..1023] of Char;
count: LongInt;
i: Integer;
c: Char;
begin
// Note: this method only works on Seekable InputStreams (for bdmStrict we also get the Size property)
if DecodedSize<>-1 then Exit(DecodedSize);
ipos := InputStream.Position; // save position in input stream
case Mode of
bdmMIME: begin
// read until end of input stream or first occurence of a '='
Result := ReadBase64ByteCount; // keep number of valid base64 bytes since last Reset in Result
repeat
count := InputStream.Read(scanBuf, SizeOf(scanBuf));
for i := 0 to count-1 do begin
c := scanBuf[i];
if c in Alphabet-['='] then // base64 encoding characters except '='
Inc(Result)
else if c = '=' then // end marker '='
Break;
end;
until count = 0;
writeln(Result);
// we are now either at the end of the stream, or encountered our first '=', stored in c
if c = '=' then begin // '=' found
if Result mod 4 <= 1 then // badly placed '=', disregard last block
Result := (Result div 4) * 3
else // 4 byte block ended with '=' or '=='
Result := (Result div 4) * 3 + Result mod 4 - 1;
end else // end of stream
Result := (Result div 4) * 3; // number of valid 4 byte blocks times 3
end;
bdmStrict:begin
// seek to end of input stream, read last two bytes and determine size
// from InputStream size and the number of leading '=' bytes
// NB we don't raise an exception here if the input does not contains an integer multiple of 4 bytes
ipos := InputStream.Position;
isize := InputStream.Size;
Result := ((ReadBase64ByteCount + (isize - ipos) + 3) div 4) * 3;
InputStream.Seek(-2, soFromEnd);
InputStream.Read(endBytes, 2);
if endBytes[1] = '=' then begin // last byte
Dec(Result);
if endBytes[0] = '=' then // second to last byte
Dec(Result);
end;
end;
end;
InputStream.Position := ipos; // restore position in input stream
// store calculated DecodedSize
DecodedSize := Result;
end;
function TBase64DecodingStream.GetPosition: Int64;
begin
Result := CurPos;
end;
constructor TBase64DecodingStream.Create(AInputStream: TStream);
begin
Create(AInputStream, bdmMIME); // MIME mode is default
end;
constructor TBase64DecodingStream.Create(AInputStream: TStream; AMode: TBase64DecodingMode);
begin
inherited Create;
InputStream := AInputStream;
Mode := AMode;
Reset;
end;
procedure TBase64DecodingStream.Reset;
begin
InputStreamSize := -1;
BufPos := 3;
fEOF := False;
ReadBase64ByteCount := 0; // number of bytes Read form InputStream since last call to Reset
CurPos := 0; // position in decoded byte sequence since last Reset
DecodedSize := -1; // indicates unknown; will be set after first call to GetSize or when reaching end of stream
BufPos := 3; // signals we need to read & decode a new block of 4 bytes
FEOF := False;
end;
function TBase64DecodingStream.Read(var Buffer; Count: Longint): Longint;
var
p: PChar;
b: Char;
ReadBuf: array[0..3] of Byte;
ToRead, OrgToRead, HaveRead, ReadOK, i, j: Integer;
p: PByte;
b: byte;
ReadBuf: array[0..3] of Byte; // buffer to store last read 4 input bytes
ToRead, OrgToRead, HaveRead, ReadOK, i: Integer;
procedure DetectedEnd(ASize:Int64);
begin
DecodedSize := ASize;
// Correct Count if at end of base64 input
if CurPos + Count > DecodedSize then
Count := DecodedSize - CurPos;
end;
begin
if Count <= 0 then exit(0);
if InputStreamSize <> -1 then begin
if CurPos + Count > InputStreamSize then
Count := InputStreamSize - CurPos;
if Count <= 0 then exit(0); // nothing to read, quit
if DecodedSize <> -1 then begin // try using calculated size info if possible
if CurPos + Count > DecodedSize then
Count := DecodedSize - CurPos;
if Count <= 0 then exit(0);
end;
Result := 0;
p := PChar(@Buffer);
while (Count > 0) and not fEOF do begin
p := @Buffer;
while true do begin
// get new 4-byte block if at end of Buf
if BufPos > 2 then begin
BufPos := 0;
// Read the next 4 valid bytes
ToRead := 4;
ReadOK := 0;
ToRead := 4; // number of base64 bytes left to read into ReadBuf
ReadOK := 0; // number of base64 bytes already read into ReadBuf
while ToRead > 0 do begin
OrgToRead := ToRead;
HaveRead := InputStream.Read(ReadBuf[ReadOK], ToRead);
//WriteLn('ToRead = ', ToRead, ', HaveRead = ', HaveRead, ', ReadOK=', ReadOk);
if HaveRead > 0 then begin
i := ReadOk;
while i<HaveRead do begin
ReadBuf[i] := DecTable[ReadBuf[i]];
if ReadBuf[i] = 99 then
for j := i to 3 do
ReadBuf[i] := ReadBuf[i + 1]
else begin
Inc(i);
if HaveRead > 0 then begin // if any new bytes; in ReadBuf[ReadOK .. ReadOK + HaveRead-1]
for i := ReadOK to ReadOK + HaveRead - 1 do begin
b := DecTable[ReadBuf[i]];
if b <> NA then begin // valid base64 alphabet character ('=' inclusive)
ReadBuf[ReadOK] := b;
Inc(ReadOK);
Dec(ToRead);
end else if Mode=bdmStrict then begin // non-valid character
raise EBase64DecodingException.CreateFmt(SStrictNonBase64Char,[]);
end;
end;
end;
if HaveRead <> OrgToRead then begin
//WriteLn('Ende? ReadOK=', ReadOK, ', count=', Count);
if HaveRead <> OrgToRead then begin // less than 4 base64 bytes could be read; end of input stream
//WriteLn('End: ReadOK=', ReadOK, ', count=', Count);
for i := ReadOK to 3 do
ReadBuf[i] := Ord('=');
fEOF := True;
if ReadOK < 2 then exit; // Not enough data available in input stream
break;
ReadBuf[i] := 0; // pad buffer with zeros so decoding of 4-bytes will be correct
if (Mode = bdmStrict) and (ReadOK > 0) then
raise EBase64DecodingException.CreateFmt(SStrictInputTruncated,[]);
Break;
end;
end;
// Check for fill bytes
if (Count >= 2) and (ReadBuf[3] = Ord('=')) then begin
//WriteLn('Endemarkierung!');
fEOF := True;
if ReadBuf[2] = Ord('=') then
Count := 1
else
Count := 2;
Inc(ReadBase64ByteCount, ReadOK);
// Check for pad characters
case Mode of
bdmStrict:begin
if ReadOK = 0 then // end of input stream was reached at 4-byte boundary
DetectedEnd(CurPos)
else if (ReadBuf[0] = PC) or (ReadBuf[1] = PC) then
raise EBase64DecodingException.CreateFmt(SStrictMisplacedPadChar,[]) // =BBB or B=BB
else if (ReadBuf[2] = PC) then begin
if (ReadBuf[3] <> PC) or (InputStream.Position < InputStream.Size) then
raise EBase64DecodingException.CreateFmt(SStrictMisplacedPadChar,[]); // BB=B or BB==, but not at end of input stream
DetectedEnd(CurPos + 1) // only one byte left to read; BB==, at end of input stream
end else if (ReadBuf[3] = PC) then begin
if (InputStream.Position < InputStream.Size) then
raise EBase64DecodingException.CreateFmt(SStrictMisplacedPadChar,[]); // BBB=, but not at end of input stream
DetectedEnd(CurPos + 2); // only two bytes left to read; BBB=, at end of input stream
end;
end;
bdmMIME:begin
if ReadOK = 0 then // end of input stream was reached at 4-byte boundary
DetectedEnd(CurPos)
else if (ReadBuf[0] = PC) or (ReadBuf[1] = PC) then
DetectedEnd(CurPos) // =BBB or B=BB: end here
else if (ReadBuf[2] = PC) then begin
DetectedEnd(CurPos + 1) // only one byte left to read; BB=B or BB==
end else if (ReadBuf[3] = PC) then begin
DetectedEnd(CurPos + 2); // only two bytes left to read; BBB=
end;
end;
end;
// Decode the 4 bytes in the buffer to 3 undecoded bytes
Buf[0] := ReadBuf[0] shl 2 or ReadBuf[1] shr 4;
Buf[0] := ReadBuf[0] shl 2 or ReadBuf[1] shr 4;
Buf[1] := (ReadBuf[1] and 15) shl 4 or ReadBuf[2] shr 2;
Buf[2] := (ReadBuf[2] and 3) shl 6 or ReadBuf[3];
Buf[2] := (ReadBuf[2] and 3) shl 6 or ReadBuf[3];
end;
if Count <= 0 then begin
Break;
end;
p[0] := Chr(Buf[BufPos]);
// write one byte to Count
p^ := Buf[BufPos];
Inc(p);
Inc(BufPos);
Inc(CurPos);
Dec(Count);
Inc(Result);
end;
// check for EOF
if (DecodedSize <> -1) and (CurPos >= DecodedSize) then begin
FEOF := true;
end;
end;
function TBase64DecodingStream.Write(const Buffer; Count: Longint): Longint;
@ -262,35 +419,9 @@ begin
end;
function TBase64DecodingStream.Seek(Offset: Longint; Origin: Word): Longint;
var
ipos: LongInt;
endbytes: array[0..1] of Char;
begin
{This will work only if the input stream supports seeking / Size. If not, the
input stream will raise an exception; we don't handle them here but pass them
to the caller.}
if InputStreamSize = -1 then begin
ipos := InputStream.Position;
InputStreamSize := ((InputStream.Size - ipos + 3) div 4) * 3;
InputStream.Seek(-2, soFromEnd);
InputStream.Read(endbytes, 2);
InputStream.Position := ipos;
if endbytes[1] = '=' then begin
Dec(InputStreamSize);
if endbytes[0] = '=' then
Dec(InputStreamSize);
end;
end;
// This stream only supports the Seek modes needed for determining its size
if (Origin = soFromCurrent) and (Offset = 0) then
Result := CurPos
else if (Origin = soFromEnd) and (Offset = 0) then
Result := InputStreamSize
else if (Origin = soFromBeginning) and (Offset = CurPos) then
Result := CurPos
else
raise EStreamError.Create('Invalid stream operation');
// TODO: implement Seeking in TBase64DecodingStream
raise EStreamError.Create('Invalid stream operation');
end;