//
//  JSbcoder.m
//
//  Created by Jon Shier on 3/4/05.
//</code>
 
<code>#import "JSbcoder.h"
 
@implementation JSbcoder
 
- (NSDictionary *) decodeTorrentFileData: (NSData *) torrentData {
 
//Need error checking. Check that the data starts with d.
 
const char *torrentFileBytes = [torrentData bytes];
 
[self setDataLength: [torrentData length]];
 
return [NSDictionary dictionaryWithDictionary: [self decodeDictionaryFromBytes: torrentFileBytes withRange: NSMakeRange(1, dataLength - 2)]];
}
 
- (NSDictionary *) convertDictionaryDataToStrings: (NSDictionary *) torrentDictionary {
NSMutableArray *keyArray = [NSMutableArray arrayWithArray: [torrentDictionary allKeys]];
NSMutableArray *valueArray = [NSMutableArray arrayWithArray: [torrentDictionary allValues]];
 
for (int i = 0; i &lt; [keyArray count]; i++) {
[keyArray replaceObjectAtIndex: i withObject: [NSString stringWithUTF8String: [[keyArray objectAtIndex: i] bytes]]];
}
 
for (int i = 0; i &lt; [valueArray count]; i++) {
if([[valueArray objectAtIndex: i] isKindOfClass: [NSData class]] &amp;&amp; ![[keyArray objectAtIndex: i] isEqualToString: @"pieces"]) {
if(IsEmpty([NSString stringWithUTF8String: [[valueArray objectAtIndex: i] bytes]])) NSLog(@"A value is nil, value array is: %@ nil value at index %i which is %@ string of which is %@\n", valueArray, i, [valueArray objectAtIndex: i], [NSString stringWithUTF8String: [[valueArray objectAtIndex: i] bytes]]);
[valueArray replaceObjectAtIndex: i withObject: [NSString stringWithUTF8String: [[valueArray objectAtIndex: i] bytes]]];
} else if([[valueArray objectAtIndex: i] isKindOfClass: [NSDictionary class]]) {
[valueArray replaceObjectAtIndex: i withObject: [self convertDictionaryDataToStrings: [valueArray objectAtIndex: i]]];
}
}
 
return [NSDictionary dictionaryWithObjects: valueArray forKeys: keyArray];
}
 
- (NSNumber *) decodeIntegerFromBytes: (const char*) torrentData withRange: (NSRange) range {
 
return [NSNumber numberWithInt: [[[[NSString alloc] initWithBytes:torrentData + range.location length:range.length encoding:NSUTF8StringEncoding] autorelease] intValue]];
}
 
- (NSData *) decodeStringAndReturnDataFromBytes: (const char*) torrentData withRange: (NSRange) range {
 
return [[NSData dataWithBytes: torrentData length: dataLength] subdataWithRange: range];
}
 
- (unsigned int) findBlockRangeAtIndex: (unsigned int) index inBytes: (const char *) torrentData {
int j = 0;
int blockLength = 1;
 
//Need error checking
 
while (index + blockLength &lt; dataLength) {
blockLength++;
if (torrentData[index + blockLength] == 'i') {
for (j = 1; j &lt; dataLength; j++) {
if (torrentData[index + j + blockLength] == 'e') break;
}
blockLength += j;
} else if (isdigit(torrentData[index + blockLength])) {
NSRange range;
for (j = 0; j &lt; dataLength; j++) {
if (isdigit(torrentData[j + index + blockLength]) &amp;&amp; torrentData[j + index + 1 + blockLength] == ':') {
range.location = index + blockLength;
range.length = j + 1;
break;
}
}
blockLength += j + 1;
j = [[[[NSString alloc] initWithBytes:torrentData + range.location length:range.length encoding:NSUTF8StringEncoding] autorelease] intValue];
blockLength += j;
} else if (torrentData[index + blockLength] == 'l') {
blockLength += [self findBlockRangeAtIndex: (index + blockLength) inBytes: torrentData] - 1;
} else if (torrentData[index + blockLength] == 'd') {
blockLength += [self findBlockRangeAtIndex: (index + blockLength) inBytes: torrentData] - 1;
} else if (torrentData[index + blockLength] == 'e') {
break;
}
}
 
return blockLength + 1;
}
 
- (NSArray *) decodeListFromBytes: (const char *) torrentData withRange: (NSRange) range {
 
//Insert error checking
 
return [NSArray arrayWithArray:[self createArrayFromData: torrentData withRange: range]];
}
 
- (NSDictionary *) decodeDictionaryFromBytes: (const char *) torrentData withRange: (NSRange) range {
 
//Need error checking
 
NSArray *methodArray = [NSArray arrayWithArray:[self createArrayFromData: torrentData withRange: range]];
 
NSMutableArray *keyArray = [NSMutableArray array];
NSMutableArray *valueArray = [NSMutableArray array];
for(int i = 0; i &lt; [methodArray count]; i += 2) {
if([[methodArray objectAtIndex: i] isKindOfClass: [NSData class]]) {
if(IsEmpty([NSString stringWithUTF8String:[[methodArray objectAtIndex: i] bytes]])) {
[keyArray addObject: [methodArray objectAtIndex: i]];
} else [keyArray addObject: [NSString stringWithUTF8String:[[methodArray objectAtIndex: i] bytes]]];
} else {
[keyArray addObject: [methodArray objectAtIndex: i]];
}
}
 
for(int i = 1; i &lt; [methodArray count]; i += 2) {
if([[methodArray objectAtIndex: i] isKindOfClass: [NSData class]] ) {
if(IsEmpty([NSString stringWithUTF8String:[[methodArray objectAtIndex: i] bytes]])) {
[valueArray addObject: [methodArray objectAtIndex: i]];
} else [valueArray addObject: [NSString stringWithUTF8String:[[methodArray objectAtIndex: i] bytes]]];
} else {
[valueArray addObject: [methodArray objectAtIndex: i]];
}
}
return [NSDictionary dictionaryWithObjects: valueArray forKeys: keyArray];
}
 
- (void) setDataLength: (unsigned int) torrentFileDataLength {
dataLength = torrentFileDataLength;
}
 
- (NSArray *) createArrayFromData: (const char *) torrentData withRange: (NSRange) range {
NSMutableArray *methodArray = [NSMutableArray array];
 
unsigned int j = 0;
unsigned int k = range.length + range.location;
for (int i = range.location; i &lt;= k; i++) {
if (torrentData[i] == 'i') {
for (j = 1; j &lt; dataLength; j++) {
if (torrentData[i + j] == 'e') break;
}
range.location = i + 1;
range.length = j - 1;
[methodArray addObject: [self decodeIntegerFromBytes: torrentData withRange: range]];
i += j;
} else if (isdigit(torrentData[i])) {
for (j = 0; j &lt; dataLength; j++) {
if (isdigit(torrentData[j + i]) &amp;&amp; torrentData[j + i + 1] == ':') {
range.location = i;
range.length = j + 1;
break;
}
}
i += range.length;
j = [[[[NSString alloc] initWithBytes:torrentData + range.location length:range.length encoding:NSUTF8StringEncoding] autorelease] intValue];
range.location += range.length + 1;
range.length = j;
[methodArray addObject: [self decodeStringAndReturnDataFromBytes: torrentData withRange: range]];
i += range.length;
} else if (torrentData[i] == 'l') {
range.location = i + 1;
range.length = [self findBlockRangeAtIndex: i inBytes: torrentData] - 2;
[methodArray addObject: [self decodeListFromBytes: torrentData withRange: range]];
i += range.length + 1;
} else if (torrentData[i] == 'd') {
range.location = i + 1;
range.length = [self findBlockRangeAtIndex: i inBytes: torrentData] - 2;
[methodArray addObject: [self decodeDictionaryFromBytes: torrentData withRange: range]];
i += range.length + 1;
}
}
return methodArray;
}
 
@end