NSData-WIFoundation.m

/* $Id$ */

/*
 *  Copyright (c) 2003-2009 Axel Andersson
 *  All rights reserved.
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions
 *  are met:
 *  1. Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *  2. Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#import <WiredFoundation/NSData-WIFoundation.h>

@implementation NSData(WIDataChecksum)

+ (NSData *)dataWithBase64EncodedString:(NSString *)string {
        NSMutableData                   *mutableData;
        NSData                                  *data;
        const unsigned char             *buffer;
        unsigned char                   ch, inbuffer[4], outbuffer[3];
        NSUInteger                              i, length, count, position, offset;
        BOOL                                    ignore, stop, end;
        
        data = [string dataUsingEncoding:NSASCIIStringEncoding];
        length = [data length];
        position = offset = 0;
        buffer = [data bytes];
        mutableData = [NSMutableData dataWithCapacity:length];
        
        while(position < length) {
                ignore = end = NO;
                ch = buffer[position++];
                
                if(ch >= 'A' && ch <= 'Z')
                        ch = ch - 'A';
                else if(ch >= 'a' && ch <= 'z')
                        ch = ch - 'a' + 26;
                else if(ch >= '0' && ch <= '9')
                        ch = ch - '0' + 52;
                else if(ch == '+')
                        ch = 62;
                else if(ch == '=')
                        end = YES;
                else if(ch == '/')
                        ch = 63;
                else
                        ignore = YES;
                
                if(!ignore) {
                        count = 3;
                        stop = NO;
                        
                        if(end) {
                                if(offset == 0)
                                        break;
                                else if(offset == 1 || offset == 2)
                                        count = 1;
                                else
                                        count = 2;
                                
                                offset = 3;
                                stop = YES;
                        }
                        
                        inbuffer[offset++] = ch;
                        
                        if(offset == 4) {
                                outbuffer[0] =  (inbuffer[0]         << 2) | ((inbuffer[1] & 0x30) >> 4);
                                outbuffer[1] = ((inbuffer[1] & 0x0F) << 4) | ((inbuffer[2] & 0x3C) >> 2);
                                outbuffer[2] = ((inbuffer[2] & 0x03) << 6) |  (inbuffer[3] & 0x3F);
                                
                                for(i = 0; i < count; i++)
                                        [mutableData appendBytes:&outbuffer[i] length:1];

                                offset = 0;
                        }
                        
                        if(stop)
                                break;
                }
        }
        
        return mutableData;
}



- (NSString *)base64EncodedString {
        NSMutableString                 *string;
        const unsigned char             *buffer;
        unsigned char                   inbuffer[3], outbuffer[4];
        NSUInteger                              i, count, length, position, remaining;
        static char                             table[] =
                "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
        
        length = [self length];
        buffer = [self bytes];
        position = 0;
        string = [NSMutableString stringWithCapacity:(NSUInteger) (length * (4.0f / 3.0f)) + 4];
        
        while(position < length) {
                for(i = 0; i < 3; i++) {
                        if(position + i < length)
                                inbuffer[i] = buffer[position + i];
                        else
                                inbuffer[i] = '\0';
                }
                
                outbuffer[0] =  (inbuffer[0] & 0xFC) >> 2;
                outbuffer[1] = ((inbuffer[0] & 0x03) << 4) | ((inbuffer[1] & 0xF0) >> 4);
                outbuffer[2] = ((inbuffer[1] & 0x0F) << 2) | ((inbuffer[2] & 0xC0) >> 6);
                outbuffer[3] =   inbuffer[2] & 0x3F;
                
                remaining = length - position;
                
                if(remaining == 1)
                        count = 2;
                else if(remaining == 2)
                        count = 3;
                else
                        count = 4;
                
                for(i = 0; i < count; i++)
                        [string appendFormat:@"%c", table[outbuffer[i]]];
                
                for(i = count; i < 4; i++)
                        [string appendFormat:@"%c", '='];
                
                position += 3;
        }
        
        return string;
}



#pragma mark -

- (NSString *)SHA1 {
        CC_SHA1_CTX                             c;
        static unsigned char    hex[] = "0123456789abcdef";
        unsigned char                   sha[CC_SHA1_DIGEST_LENGTH];
        char                                    text[CC_SHA1_DIGEST_LENGTH * 2 + 1];
        NSUInteger                              i;

        CC_SHA1_Init(&c);
        CC_SHA1_Update(&c, [self bytes], (CC_LONG)[self length]);
        CC_SHA1_Final(sha, &c);

        for(i = 0; i < CC_SHA1_DIGEST_LENGTH; i++) {
                text[i + i]                     = hex[sha[i] >> 4];
                text[i + i + 1]         = hex[sha[i] & 0x0F];
        }

        text[i + i] = '\0';

        return [NSString stringWithUTF8String:text];
}

@end