idcoderheader.pas

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{ $HDR$}
{**********************************************************************}
{ Unit archived using Team Coherence                                   }
{ Team Coherence is Copyright 2002 by Quality Software Components      }
{                                                                      }
{ For further information / comments, visit our WEB site at            }
{ http://www.TeamCoherence.com                                         }
{**********************************************************************}
{}
{ $Log:  13756: IdCoderHeader.pas
{
{   Rev 1.13    9/8/2004 8:55:46 PM  JPMugaas
{ Fix for compile problem where a char is being compared with an incompatible
{ type in some compilers.
}
{
{   Rev 1.12    02/07/2004 21:59:28  CCostelloe
{ Bug fix
}
{
{   Rev 1.11    17/06/2004 14:19:00  CCostelloe
{ Bug fix for long subject lines that have characters needing CharSet encoding
}
{
{   Rev 1.10    23/04/2004 20:33:04  CCostelloe
{ Minor change to support From headers holding multiple addresses
}
{
{   Rev 1.9    2004.02.03 5:44:58 PM  czhower
{ Name changes
}
{
{   Rev 1.8    24/01/2004 19:08:14  CCostelloe
{ Cleaned up warnings
}
{
{   Rev 1.7    1/22/2004 3:56:38 PM  SPerry
{ fixed set problems
}
{
{   Rev 1.6    2004.01.22 2:34:58 PM  czhower
{ TextIsSame + D8 bug workaround
}
{
    Rev 1.5    10/16/2003 11:11:02 PM  DSiders
  Added localization comments.
}
{
{   Rev 1.4    10/8/2003 9:49:36 PM  GGrieve
{ Use IdDelete
}
{
{   Rev 1.3    6/10/2003 5:48:46 PM  SGrobety
{ DotNet updates
}
{
{   Rev 1.2    04/09/2003 20:35:28  CCostelloe
{ Parameter AUseAddressForNameIfNameMissing (defaulting to False to preserve
{ existing code) added to EncodeAddressItem
}
{
{   Rev 1.1    2003.06.23 9:46:52 AM  czhower
{ Russian, Ukranian support for headers.
}
{
{   Rev 1.0    11/14/2002 02:14:46 PM  JPMugaas
}
unit IdCoderHeader;

//TODO: Optimize and restructure code
//TODO: Redo this unit to fit with the new coders and use the exisiting MIME stuff

{
2002-08-21 JM Berg
 - brought in line with the RFC regarding
   whitespace between encoded words
 - added logic so that lines that already seem encoded are really encoded again
   (so that if a user types =?iso8859-1?Q?======?= its really encoded again
   and displayed like that on the other side)
2001-Nov-18 Peter Mee
 - Fixed multiple QP decoding in single header.
11-10-2001 - J. Peter Mugaas
  - tiny fix for 8bit header encoding suggested by Andrew P.Rybin}
interface

uses
  IdEMailAddress;

type
  TTransfer = (bit7, bit8, iso2022jp);
  CSET = set of AnsiChar;
  
// Procs
  function EncodeAddressItem(EmailAddr:TIdEmailAddressItem; const HeaderEncoding: Char;
    TransferHeader: TTransfer; MimeCharSet: string; AUseAddressForNameIfNameMissing: Boolean = False): string;
  function EncodeHeader(const Header: string; specials : CSET; const HeaderEncoding: Char;
   TransferHeader: TTransfer; MimeCharSet: string): string;
  function Encode2022JP(const S: ansistring): string;
  function EncodeAddress(EmailAddr:TIdEMailAddressList; const HeaderEncoding: Char;
    TransferHeader: TTransfer; MimeCharSet: string; AUseAddressForNameIfNameMissing: Boolean = False): string;
  function DecodeHeader(Header: string):string;
  function Decode2022JP(const S: string): string;
  Procedure DecodeAddress(EMailAddr : TIdEmailAddressItem);
  Procedure DecodeAddresses(AEMails : String; EMailAddr : TIdEmailAddressList);

implementation

uses
  IdGlobal,
  IdGlobalProtocols,
  SysUtils;

const
  csSPECIALS: CSET = ['(', ')', '[', ']', '<', '>', ':', ';', '.', ',', '@', '\', '"'];  {Do not Localize}

  kana_tbl : array[#$A1..#$DF] of Word = (
    $2123,$2156,$2157,$2122,$2126,$2572,$2521,$2523,$2525,$2527,
    $2529,$2563,$2565,$2567,$2543,$213C,$2522,$2524,$2526,$2528,
    $252A,$252B,$252D,$252F,$2531,$2533,$2535,$2537,$2539,$253B,
    $253D,$253F,$2541,$2544,$2546,$2548,$254A,$254B,$254C,$254D,
    $254E,$254F,$2552,$2555,$2558,$255B,$255E,$255F,$2560,$2561,
    $2562,$2564,$2566,$2568,$2569,$256A,$256B,$256C,$256D,$256F,
    $2573,$212B,$212C);

  vkana_tbl : array[#$A1..#$DF] of Word = (
    $0000,$0000,$0000,$0000,$0000,$0000,$0000,$0000,$0000,$0000,
    $0000,$0000,$0000,$0000,$0000,$0000,$0000,$0000,$2574,$0000,
    $0000,$252C,$252E,$2530,$2532,$2534,$2536,$2538,$253A,$253C,
    $253E,$2540,$2542,$2545,$2547,$2549,$0000,$0000,$0000,$0000,
    $0000,$2550,$2553,$2556,$2559,$255C,$0000,$0000,$0000,$0000,
    $0000,$0000,$0000,$0000,$0000,$0000,$0000,$0000,$0000,$0000,
    $0000,$0000,$0000);

  sj1_tbl : array[#128..#255] of Byte = (
    $00,$21,$23,$25,$27,$29,$2B,$2D,$2F,$31,$33,$35,$37,$39,$3B,$3D,
    $3F,$41,$43,$45,$47,$49,$4B,$4D,$4F,$51,$53,$55,$57,$59,$5B,$5D,
    $00,$01,$01,$01,$01,$01,$01,$01,$01,$01,$01,$01,$01,$01,$01,$01,
    $01,$01,$01,$01,$01,$01,$01,$01,$01,$01,$01,$01,$01,$01,$01,$01,
    $01,$01,$01,$01,$01,$01,$01,$01,$01,$01,$01,$01,$01,$01,$01,$01,
    $01,$01,$01,$01,$01,$01,$01,$01,$01,$01,$01,$01,$01,$01,$01,$01,
    $5F,$61,$63,$65,$67,$69,$6B,$6D,$6F,$71,$73,$75,$77,$79,$7B,$7D,
    $02,$02,$02,$02,$02,$02,$02,$02,$02,$02,$02,$02,$02,$00,$00,$00);

  sj2_tbl : array[AnsiChar] of Word = (
    $0000,$0000,$0000,$0000,$0000,$0000,$0000,$0000,$0000,$0000,
    $0000,$0000,$0000,$0000,$0000,$0000,$0000,$0000,$0000,$0000,
    $0000,$0000,$0000,$0000,$0000,$0000,$0000,$0000,$0000,$0000,
    $0000,$0000,$0000,$0000,$0000,$0000,$0000,$0000,$0000,$0000,
    $0000,$0000,$0000,$0000,$0000,$0000,$0000,$0000,$0000,$0000,
    $0000,$0000,$0000,$0000,$0000,$0000,$0000,$0000,$0000,$0000,
    $0000,$0000,$0000,$0000,$0021,$0022,$0023,$0024,$0025,$0026,
    $0027,$0028,$0029,$002A,$002B,$002C,$002D,$002E,$002F,$0030,
    $0031,$0032,$0033,$0034,$0035,$0036,$0037,$0038,$0039,$003A,
    $003B,$003C,$003D,$003E,$003F,$0040,$0041,$0042,$0043,$0044,
    $0045,$0046,$0047,$0048,$0049,$004A,$004B,$004C,$004D,$004E,
    $004F,$0050,$0051,$0052,$0053,$0054,$0055,$0056,$0057,$0058,
    $0059,$005A,$005B,$005C,$005D,$005E,$005F,$0000,$0060,$0061,
    $0062,$0063,$0064,$0065,$0066,$0067,$0068,$0069,$006A,$006B,
    $006C,$006D,$006E,$006F,$0070,$0071,$0072,$0073,$0074,$0075,
    $0076,$0077,$0078,$0079,$007A,$007B,$007C,$007D,$007E,$0121,
    $0122,$0123,$0124,$0125,$0126,$0127,$0128,$0129,$012A,$012B,
    $012C,$012D,$012E,$012F,$0130,$0131,$0132,$0133,$0134,$0135,
    $0136,$0137,$0138,$0139,$013A,$013B,$013C,$013D,$013E,$013F,
    $0140,$0141,$0142,$0143,$0144,$0145,$0146,$0147,$0148,$0149,
    $014A,$014B,$014C,$014D,$014E,$014F,$0150,$0151,$0152,$0153,
    $0154,$0155,$0156,$0157,$0158,$0159,$015A,$015B,$015C,$015D,
    $015E,$015F,$0160,$0161,$0162,$0163,$0164,$0165,$0166,$0167,
    $0168,$0169,$016A,$016B,$016C,$016D,$016E,$016F,$0170,$0171,
    $0172,$0173,$0174,$0175,$0176,$0177,$0178,$0179,$017A,$017B,
    $017C,$017D,$017E,$0000,$0000,$0000);

  base64_tbl: array [0..63] of Char = (
    'A','B','C','D','E','F','G','H',     {Do not Localize}
    'I','J','K','L','M','N','O','P',      {Do not Localize}
    'Q','R','S','T','U','V','W','X',      {Do not Localize}
    'Y','Z','a','b','c','d','e','f',      {Do not Localize}
    'g','h','i','j','k','l','m','n',      {Do not Localize}
    'o','p','q','r','s','t','u','v',       {Do not Localize}
    'w','x','y','z','0','1','2','3',       {Do not Localize}
    '4','5','6','7','8','9','+','/');      {Do not Localize}

function EncodeAddressItem(EmailAddr:TIdEmailAddressItem; const HeaderEncoding: Char;
  TransferHeader: TTransfer; MimeCharSet: string; AUseAddressForNameIfNameMissing: Boolean = False): string;
var
  S : string;
  I : Integer;
  NeedEncode : Boolean;
begin
  if ((AUseAddressForNameIfNameMissing = True) and (EmailAddr.Name = '')) then begin
    {CC: Use Address as Name...}
    EmailAddr.Name := EmailAddr.Address;
  end;
  if EmailAddr.Name <> '' then  {Do not Localize}
  begin
    NeedEncode := False;
    for I := 1 to Length(EmailAddr.Name) do
    begin
      if (EmailAddr.Name[I] < #32) or (EmailAddr.Name[I] >= #127) then
      begin
        NeedEncode := True;
        Break;
      end;
    end;
    if NeedEncode then
      S := EncodeHeader(EmailAddr.Name, csSPECIALS, HeaderEncoding, TransferHeader, MimeCharSet)
    else
    begin                { quoted string }
      S := '"';           {Do not Localize}
      for I := 1 to Length(EmailAddr.Name) do
      begin              { quote special characters }
        if (EmailAddr.Name[I] = '\') or (EmailAddr.Name[I] = '"') then S := S + '\';    {Do not Localize}
        S := S + EmailAddr.Name[I];
      end;
      S := S + '"';   {Do not Localize}
    end;
    Result := Format('%s <%s>', [S, EmailAddr.Address])    {Do not Localize}
  end
  else Result := Format('%s', [EmailAddr.Address]);     {Do not Localize}
end;

function B64(AChar: Char): Byte;
//TODO: Make this use the more efficient MIME Coder
var
  i: Integer;
begin
  for i := Low(base64_tbl) to High(base64_tbl) do begin
    if AChar = base64_tbl[i] then begin
      Result := i;
      exit;
    end;
  end;
  Result := 0;
end;

function DecodeHeader(Header: string):string;
const
  WhiteSpace = [LF, CR, CHAR32, TAB];
var
  i, l: Integer;
  HeaderEncoding,
  HeaderCharSet,
  s: string;
  a3: array [1..3] of byte;
  a4: array [1..4] of byte;
  LEncodingStartPos,encodingendpos:Integer;
  LPreviousEncodingStartPos: integer;
  substring: string;
  EncodingFound: Boolean;
  OnlyWhitespace: boolean;
  EncodingBeforeEnd: integer;
begin
  // Get the Charset part.
  EncodingBeforeEnd := -1;
  LEncodingStartPos := PosIdx('=?ISO', UpperCase(Header), 1); {do not localize}
  if LEncodingStartPos = 0 then begin
    LEncodingStartPos := PosIdx('=?WINDOWS', UpperCase(Header), 1); {do not localize}
  end;
  if LEncodingStartPos = 0 then begin
    LEncodingStartPos := PosIdx('=?KOI8', UpperCase(Header), 1); {do not localize}
  end;

  while LEncodingStartPos > 0 do begin
    // Assume we will find the encoding
    EncodingFound := True;

    //we need 3 more question marks first and after that a '?='    {Do not Localize}
    //to find the end of the substring, we can't just search for '?=',    {Do not Localize}
    //example: '=?ISO-8859-1?Q?=E4?='    {Do not Localize}
    encodingendpos := PosIdx('?', UpperCase(Header),LEncodingStartPos+5);  {Do not Localize}
    if encodingendpos = 0 then begin
      EncodingFound := False;
    end else begin
      // valid encoded words can not contain spaces
      // if the user types something *almost* like an encoded word,
      // and its sent as-is, we need to find this!!
      for i := LEncodingStartPos to encodingendpos-1 do begin
        if CharIsInSet(Header, i, Whitespace) then begin
          EncodingFound := false;
          break;
        end;
      end;
    end;

    if EncodingFound then
    begin
      encodingendpos:=PosIdx('?', UpperCase(Header),encodingendpos+1);  {Do not Localize}
      if encodingendpos=0 then
      begin
        EncodingFound := false;
      end else begin
        for i := LEncodingStartPos to encodingendpos-1 do begin
          if CharIsInSet(Header, i, Whitespace) then begin
            EncodingFound := false;
            break;
          end;
        end;
      end;
    end;

    if EncodingFound then
    begin
      encodingendpos:=PosIdx('?=', UpperCase(Header),encodingendpos+1);  {Do not Localize}
      if encodingendpos > 0 then
      begin
        for i := LEncodingStartPos to encodingendpos-1 do begin
          if CharIsInSet(Header, i, Whitespace) then begin
            EncodingFound := false;
            break;
          end;
        end;

        if EncodingFound then begin
          substring:=Copy(Header,LEncodingStartPos,encodingendpos-LEncodingStartPos+2);
          //now decode the substring
          for i := 1 to 3 do
          begin
            l := Pos('?', substring);   {Do not Localize}
            substring := Copy(substring, l+1, Length(substring) - l + 1 );
            if i = 1 then
            begin
              HeaderCharSet := Copy(substring, 1, Pos('?', substring)-1)  {Do not Localize}
            end else if i = 2 then
            begin
              HeaderEncoding := copy(substring,1,1);
            end;
          end;

          //now Substring needs to end with '?=' otherwise give up!    {Do not Localize}
          if Copy(substring,Length(substring)-1,2)<>'?=' then    {Do not Localize}
          begin
            EncodingFound := false;
          end;
        end;

        if (EncodingBeforeEnd>=0) and EncodingFound and (LEncodingStartPos > 0) then begin
          OnlyWhitespace := true;
          for i:=EncodingBeforeEnd to LEncodingStartPos-1 do begin
            if not (CharIsInSet(Header, i, WhiteSpace)) then begin
              OnlyWhitespace := false;
              break;
            end;
          end;
          if OnlyWhitespace then begin
            Delete(Header, EncodingBeforeEnd, LEncodingStartPos-EncodingBeforeEnd);
            encodingendpos := encodingendpos - (LEncodingStartPos-encodingbeforeend);
            LEncodingStartPos := EncodingBeforeEnd;
          end;
        end;

        // Get the HeaderEncoding
        if TextIsSame(HeaderEncoding, 'Q') {Do not Localize}
        and EncodingFound then begin
          i := 1;
          s := '';        {Do not Localize}
          repeat // substring can be accessed by index here, because we know that it ends with '?='    {Do not Localize}
            if substring[i] = '_' then  {Do not Localize}
            begin
              s := s + ' ';    {Do not Localize}
            end else if (substring[i] = '=') and (Length(substring)>=i+2+2) then //make sure we can access i+2 and '?=' is still beyond    {Do not Localize}
            begin
              s := s + chr(StrToInt('$' + substring[i+1] + substring[i+2]));   {Do not Localize}
              inc(i,2);
            end else
            begin
              s := s + substring[i];
            end;
            inc(i);
          until (substring[i]='?') and (substring[i+1]='=')   {Do not Localize}
        end else if EncodingFound then
        begin
          while Length(substring) >= 4 do
          begin
            a4[1] := b64(substring[1]);
            a4[2] := b64(substring[2]);
            a4[3] := b64(substring[3]);
            a4[4] := b64(substring[4]);
            a3[1] := Byte((a4[1] shl 2) or (a4[2] shr 4));
            a3[2] := Byte((a4[2] shl 4) or (a4[3] shr 2));
            a3[3] := Byte((a4[3] shl 6) or (a4[4] shr 0));
            substring := Copy(substring, 5, Length(substring));
            s := s + CHR(a3[1]) + CHR(a3[2]) + CHR(a3[3]);
          end;
        end;

        if EncodingFound then
        begin
          if TextIsSame(HeaderCharSet, 'ISO-2022-JP') then  {Do not Localize}
          begin
            substring := Decode2022JP(s);
          end else
          begin
            substring := s;
          end;

          //replace old substring in header with decoded one:
          header := Copy(header, 1, LEncodingStartPos - 1)