michael@0: /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: #include "plbase64.h"
michael@0: #include "prlog.h" /* For PR_NOT_REACHED */
michael@0: #include "prmem.h" /* for malloc / PR_MALLOC */
michael@0: 
michael@0: #include <string.h> /* for strlen */
michael@0: 
michael@0: static unsigned char *base = (unsigned char *)"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
michael@0: 
michael@0: static void
michael@0: encode3to4
michael@0: (
michael@0:     const unsigned char    *src,
michael@0:     unsigned char          *dest
michael@0: )
michael@0: {
michael@0:     PRUint32 b32 = (PRUint32)0;
michael@0:     PRIntn i, j = 18;
michael@0: 
michael@0:     for( i = 0; i < 3; i++ )
michael@0:     {
michael@0:         b32 <<= 8;
michael@0:         b32 |= (PRUint32)src[i];
michael@0:     }
michael@0: 
michael@0:     for( i = 0; i < 4; i++ )
michael@0:     {
michael@0:         dest[i] = base[ (PRUint32)((b32>>j) & 0x3F) ];
michael@0:         j -= 6;
michael@0:     }
michael@0: 
michael@0:     return;
michael@0: }
michael@0: 
michael@0: static void
michael@0: encode2to4
michael@0: (
michael@0:     const unsigned char    *src,
michael@0:     unsigned char          *dest
michael@0: )
michael@0: {
michael@0:     dest[0] = base[ (PRUint32)((src[0]>>2) & 0x3F) ];
michael@0:     dest[1] = base[ (PRUint32)(((src[0] & 0x03) << 4) | ((src[1] >> 4) & 0x0F)) ];
michael@0:     dest[2] = base[ (PRUint32)((src[1] & 0x0F) << 2) ];
michael@0:     dest[3] = (unsigned char)'=';
michael@0:     return;
michael@0: }
michael@0: 
michael@0: static void
michael@0: encode1to4
michael@0: (
michael@0:     const unsigned char    *src,
michael@0:     unsigned char          *dest
michael@0: )
michael@0: {
michael@0:     dest[0] = base[ (PRUint32)((src[0]>>2) & 0x3F) ];
michael@0:     dest[1] = base[ (PRUint32)((src[0] & 0x03) << 4) ];
michael@0:     dest[2] = (unsigned char)'=';
michael@0:     dest[3] = (unsigned char)'=';
michael@0:     return;
michael@0: }
michael@0: 
michael@0: static void
michael@0: encode
michael@0: (
michael@0:     const unsigned char    *src,
michael@0:     PRUint32                srclen,
michael@0:     unsigned char          *dest
michael@0: )
michael@0: {
michael@0:     while( srclen >= 3 )
michael@0:     {
michael@0:         encode3to4(src, dest);
michael@0:         src += 3;
michael@0:         dest += 4;
michael@0:         srclen -= 3;
michael@0:     }
michael@0: 
michael@0:     switch( srclen )
michael@0:     {
michael@0:         case 2:
michael@0:             encode2to4(src, dest);
michael@0:             break;
michael@0:         case 1:
michael@0:             encode1to4(src, dest);
michael@0:             break;
michael@0:         case 0:
michael@0:             break;
michael@0:         default:
michael@0:             PR_NOT_REACHED("coding error");
michael@0:     }
michael@0: 
michael@0:     return;
michael@0: }
michael@0: 
michael@0: /*
michael@0:  * PL_Base64Encode
michael@0:  *
michael@0:  * If the destination argument is NULL, a return buffer is 
michael@0:  * allocated, and the data therein will be null-terminated.  
michael@0:  * If the destination argument is not NULL, it is assumed to
michael@0:  * be of sufficient size, and the contents will not be null-
michael@0:  * terminated by this routine.
michael@0:  *
michael@0:  * Returns null if the allocation fails.
michael@0:  */
michael@0: 
michael@0: PR_IMPLEMENT(char *)
michael@0: PL_Base64Encode
michael@0: (
michael@0:     const char *src,
michael@0:     PRUint32    srclen,
michael@0:     char       *dest
michael@0: )
michael@0: {
michael@0:     if( 0 == srclen )
michael@0:     {
michael@0:         size_t len = strlen(src);
michael@0:         srclen = len;
michael@0:         /* Detect truncation. */
michael@0:         if( srclen != len )
michael@0:         {
michael@0:             return (char *)0;
michael@0:         }
michael@0:     }
michael@0: 
michael@0:     if( (char *)0 == dest )
michael@0:     {
michael@0:         PRUint32 destlen;
michael@0:         /* Ensure all PRUint32 values stay within range. */
michael@0:         if( srclen > (PR_UINT32_MAX/4) * 3 )
michael@0:         {
michael@0:             return (char *)0;
michael@0:         }
michael@0:         destlen = ((srclen + 2)/3) * 4;
michael@0:         dest = (char *)PR_MALLOC(destlen + 1);
michael@0:         if( (char *)0 == dest )
michael@0:         {
michael@0:             return (char *)0;
michael@0:         }
michael@0:         dest[ destlen ] = (char)0; /* null terminate */
michael@0:     }
michael@0: 
michael@0:     encode((const unsigned char *)src, srclen, (unsigned char *)dest);
michael@0:     return dest;
michael@0: }
michael@0: 
michael@0: static PRInt32
michael@0: codetovalue
michael@0: (
michael@0:     unsigned char c
michael@0: )
michael@0: {
michael@0:     if( (c >= (unsigned char)'A') && (c <= (unsigned char)'Z') )
michael@0:     {
michael@0:         return (PRInt32)(c - (unsigned char)'A');
michael@0:     }
michael@0:     else if( (c >= (unsigned char)'a') && (c <= (unsigned char)'z') )
michael@0:     {
michael@0:         return ((PRInt32)(c - (unsigned char)'a') +26);
michael@0:     }
michael@0:     else if( (c >= (unsigned char)'0') && (c <= (unsigned char)'9') )
michael@0:     {
michael@0:         return ((PRInt32)(c - (unsigned char)'0') +52);
michael@0:     }
michael@0:     else if( (unsigned char)'+' == c )
michael@0:     {
michael@0:         return (PRInt32)62;
michael@0:     }
michael@0:     else if( (unsigned char)'/' == c )
michael@0:     {
michael@0:         return (PRInt32)63;
michael@0:     }
michael@0:     else
michael@0:     {
michael@0:         return -1;
michael@0:     }
michael@0: }
michael@0: 
michael@0: static PRStatus
michael@0: decode4to3
michael@0: (
michael@0:     const unsigned char    *src,
michael@0:     unsigned char          *dest
michael@0: )
michael@0: {
michael@0:     PRUint32 b32 = (PRUint32)0;
michael@0:     PRInt32 bits;
michael@0:     PRIntn i;
michael@0: 
michael@0:     for( i = 0; i < 4; i++ )
michael@0:     {
michael@0:         bits = codetovalue(src[i]);
michael@0:         if( bits < 0 )
michael@0:         {
michael@0:             return PR_FAILURE;
michael@0:         }
michael@0: 
michael@0:         b32 <<= 6;
michael@0:         b32 |= bits;
michael@0:     }
michael@0: 
michael@0:     dest[0] = (unsigned char)((b32 >> 16) & 0xFF);
michael@0:     dest[1] = (unsigned char)((b32 >>  8) & 0xFF);
michael@0:     dest[2] = (unsigned char)((b32      ) & 0xFF);
michael@0: 
michael@0:     return PR_SUCCESS;
michael@0: }
michael@0: 
michael@0: static PRStatus
michael@0: decode3to2
michael@0: (
michael@0:     const unsigned char    *src,
michael@0:     unsigned char          *dest
michael@0: )
michael@0: {
michael@0:     PRUint32 b32 = (PRUint32)0;
michael@0:     PRInt32 bits;
michael@0:     PRUint32 ubits;
michael@0: 
michael@0:     bits = codetovalue(src[0]);
michael@0:     if( bits < 0 )
michael@0:     {
michael@0:         return PR_FAILURE;
michael@0:     }
michael@0: 
michael@0:     b32 = (PRUint32)bits;
michael@0:     b32 <<= 6;
michael@0: 
michael@0:     bits = codetovalue(src[1]);
michael@0:     if( bits < 0 )
michael@0:     {
michael@0:         return PR_FAILURE;
michael@0:     }
michael@0: 
michael@0:     b32 |= (PRUint32)bits;
michael@0:     b32 <<= 4;
michael@0: 
michael@0:     bits = codetovalue(src[2]);
michael@0:     if( bits < 0 )
michael@0:     {
michael@0:         return PR_FAILURE;
michael@0:     }
michael@0: 
michael@0:     ubits = (PRUint32)bits;
michael@0:     b32 |= (ubits >> 2);
michael@0: 
michael@0:     dest[0] = (unsigned char)((b32 >> 8) & 0xFF);
michael@0:     dest[1] = (unsigned char)((b32     ) & 0xFF);
michael@0: 
michael@0:     return PR_SUCCESS;
michael@0: }
michael@0: 
michael@0: static PRStatus
michael@0: decode2to1
michael@0: (
michael@0:     const unsigned char    *src,
michael@0:     unsigned char          *dest
michael@0: )
michael@0: {
michael@0:     PRUint32 b32;
michael@0:     PRUint32 ubits;
michael@0:     PRInt32 bits;
michael@0: 
michael@0:     bits = codetovalue(src[0]);
michael@0:     if( bits < 0 )
michael@0:     {
michael@0:         return PR_FAILURE;
michael@0:     }
michael@0: 
michael@0:     ubits = (PRUint32)bits;
michael@0:     b32 = (ubits << 2);
michael@0: 
michael@0:     bits = codetovalue(src[1]);
michael@0:     if( bits < 0 )
michael@0:     {
michael@0:         return PR_FAILURE;
michael@0:     }
michael@0: 
michael@0:     ubits = (PRUint32)bits;
michael@0:     b32 |= (ubits >> 4);
michael@0: 
michael@0:     dest[0] = (unsigned char)b32;
michael@0: 
michael@0:     return PR_SUCCESS;
michael@0: }
michael@0: 
michael@0: static PRStatus
michael@0: decode
michael@0: (
michael@0:     const unsigned char    *src,
michael@0:     PRUint32                srclen,
michael@0:     unsigned char          *dest
michael@0: )
michael@0: {
michael@0:     PRStatus rv;
michael@0: 
michael@0:     while( srclen >= 4 )
michael@0:     {
michael@0:         rv = decode4to3(src, dest);
michael@0:         if( PR_SUCCESS != rv )
michael@0:         {
michael@0:             return PR_FAILURE;
michael@0:         }
michael@0: 
michael@0:         src += 4;
michael@0:         dest += 3;
michael@0:         srclen -= 4;
michael@0:     }
michael@0: 
michael@0:     switch( srclen )
michael@0:     {
michael@0:         case 3:
michael@0:             rv = decode3to2(src, dest);
michael@0:             break;
michael@0:         case 2:
michael@0:             rv = decode2to1(src, dest);
michael@0:             break;
michael@0:         case 1:
michael@0:             rv = PR_FAILURE;
michael@0:             break;
michael@0:         case 0:
michael@0:             rv = PR_SUCCESS;
michael@0:             break;
michael@0:         default:
michael@0:             PR_NOT_REACHED("coding error");
michael@0:     }
michael@0: 
michael@0:     return rv;
michael@0: }
michael@0: 
michael@0: /*
michael@0:  * PL_Base64Decode
michael@0:  *
michael@0:  * If the destination argument is NULL, a return buffer is
michael@0:  * allocated and the data therein will be null-terminated.
michael@0:  * If the destination argument is not null, it is assumed
michael@0:  * to be of sufficient size, and the data will not be null-
michael@0:  * terminated by this routine.
michael@0:  * 
michael@0:  * Returns null if the allocation fails, or if the source string is 
michael@0:  * not well-formed.
michael@0:  */
michael@0: 
michael@0: PR_IMPLEMENT(char *)
michael@0: PL_Base64Decode
michael@0: (
michael@0:     const char *src,
michael@0:     PRUint32    srclen,
michael@0:     char       *dest
michael@0: )
michael@0: {
michael@0:     PRStatus status;
michael@0:     PRBool allocated = PR_FALSE;
michael@0: 
michael@0:     if( (char *)0 == src )
michael@0:     {
michael@0:         return (char *)0;
michael@0:     }
michael@0: 
michael@0:     if( 0 == srclen )
michael@0:     {
michael@0:         size_t len = strlen(src);
michael@0:         srclen = len;
michael@0:         /* Detect truncation. */
michael@0:         if( srclen != len )
michael@0:         {
michael@0:             return (char *)0;
michael@0:         }
michael@0:     }
michael@0: 
michael@0:     if( srclen && (0 == (srclen & 3)) )
michael@0:     {
michael@0:         if( (char)'=' == src[ srclen-1 ] )
michael@0:         {
michael@0:             if( (char)'=' == src[ srclen-2 ] )
michael@0:             {
michael@0:                 srclen -= 2;
michael@0:             }
michael@0:             else
michael@0:             {
michael@0:                 srclen -= 1;
michael@0:             }
michael@0:         }
michael@0:     }
michael@0: 
michael@0:     if( (char *)0 == dest )
michael@0:     {
michael@0:         /* The following computes ((srclen * 3) / 4) without overflow. */
michael@0:         PRUint32 destlen = (srclen / 4) * 3 + ((srclen % 4) * 3) / 4;
michael@0:         dest = (char *)PR_MALLOC(destlen + 1);
michael@0:         if( (char *)0 == dest )
michael@0:         {
michael@0:             return (char *)0;
michael@0:         }
michael@0:         dest[ destlen ] = (char)0; /* null terminate */
michael@0:         allocated = PR_TRUE;
michael@0:     }
michael@0: 
michael@0:     status = decode((const unsigned char *)src, srclen, (unsigned char *)dest);
michael@0:     if( PR_SUCCESS != status )
michael@0:     {
michael@0:         if( PR_TRUE == allocated )
michael@0:         {
michael@0:             PR_DELETE(dest);
michael@0:         }
michael@0: 
michael@0:         return (char *)0;
michael@0:     }
michael@0: 
michael@0:     return dest;
michael@0: }