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base64.cpp

/*
 * base64.cpp - Base64 converting functions
 * Copyright (C) 2003  Justin Karneges
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 */

#include"base64.h"

//! \class Base64 base64.h
//! \brief Base64 conversion functions.
//!
//! Converts Base64 data between arrays and strings.
//!
//! \code
//! #include "base64.h"
//!
//! ...
//!
//! // encode a block of data into base64
//! QByteArray block(1024);
//! QByteArray enc = Base64::encode(block);
//!
//!  \endcode

//!
//! Encodes array \a s and returns the result.
00041 QByteArray Base64::encode(const QByteArray &s)
{
      int i;
      int len = s.size();
      char tbl[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
      int a, b, c;

      QByteArray p((len+2)/3*4);
      int at = 0;
      for( i = 0; i < len; i += 3 ) {
            a = ((unsigned char)s[i] & 3) << 4;
            if(i + 1 < len) {
                  a += (unsigned char)s[i + 1] >> 4;
                  b = ((unsigned char)s[i + 1] & 0xF) << 2;
                  if(i + 2 < len) {
                        b += (unsigned char)s[i + 2] >> 6;
                        c = (unsigned char)s[i + 2] & 0x3F;
                  }
                  else
                        c = 64;
            }
            else
                  b = c = 64;

            p[at++] = tbl[(unsigned char)s[i] >> 2];
            p[at++] = tbl[a];
            p[at++] = tbl[b];
            p[at++] = tbl[c];
      }
      return p;
}

//!
//! Decodes array \a s and returns the result.
00075 QByteArray Base64::decode(const QByteArray &s)
{
      // return value
      QByteArray p;

      // -1 specifies invalid
      // 64 specifies eof
      // everything else specifies data

      char tbl[] = {
            -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
            -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
            -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,62,-1,-1,-1,63,
            52,53,54,55,56,57,58,59,60,61,-1,-1,-1,64,-1,-1,
            -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,10,11,12,13,14,
            15,16,17,18,19,20,21,22,23,24,25,-1,-1,-1,-1,-1,
            -1,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,
            41,42,43,44,45,46,47,48,49,50,51,-1,-1,-1,-1,-1,
            -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
            -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
            -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
            -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
            -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
            -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
            -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
            -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
      };

      // this should be a multiple of 4
      int len = s.size();

      if(len % 4)
            return p;

      p.resize(len / 4 * 3);

      int i;
      int at = 0;

      int a, b, c, d;
      c = d = 0;

      for( i = 0; i < len; i += 4 ) {
            a = tbl[(int)s[i]];
            b = tbl[(int)s[i + 1]];
            c = tbl[(int)s[i + 2]];
            d = tbl[(int)s[i + 3]];
            if((a == 64 || b == 64) || (a < 0 || b < 0 || c < 0 || d < 0)) {
                  p.resize(0);
                  return p;
            }
            p[at++] = ((a & 0x3F) << 2) | ((b >> 4) & 0x03);
            p[at++] = ((b & 0x0F) << 4) | ((c >> 2) & 0x0F);
            p[at++] = ((c & 0x03) << 6) | ((d >> 0) & 0x3F);
      }

      if(c & 64)
            p.resize(at - 2);
      else if(d & 64)
            p.resize(at - 1);

      return p;
}

//!
//! Encodes array \a a and returns the result as a string.
00141 QString Base64::arrayToString(const QByteArray &a)
{
      QByteArray b = encode(a);
      QCString c;
      c.resize(b.size()+1);
      memcpy(c.data(), b.data(), b.size());
      return QString::fromLatin1(c);
}

//!
//! Decodes string \a s and returns the result as an array.
00152 QByteArray Base64::stringToArray(const QString &s)
{
      if(s.isEmpty())
            return QByteArray();
      const char *c = s.latin1();
      int len = strlen(c);
      QByteArray b(len);
      memcpy(b.data(), c, len);
      QByteArray a = decode(b);
      return a;
}

//!
//! Encodes string \a s and returns the result as a string.
00166 QString Base64::encodeString(const QString &s)
{
      QCString c = s.utf8();
      int len = c.length();
      QByteArray b(len);
      memcpy(b.data(), c.data(), len);
      return arrayToString(b);
}

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