source: qca/trunk/examples/common/base64.cpp@ 165

/*
 * 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.
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.
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.
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.
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.
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);
}