143 lines
3.1 KiB
Objective-C
143 lines
3.1 KiB
Objective-C
//
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// Copyright (c) 2021 Open Whisper Systems. All rights reserved.
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//
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#import "ByteParser.h"
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NS_ASSUME_NONNULL_BEGIN
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@interface ByteParser ()
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@property (nonatomic, readonly) BOOL littleEndian;
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@property (nonatomic, readonly) NSData *data;
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@property (nonatomic) NSUInteger cursor;
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@property (nonatomic) BOOL hasError;
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@end
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#pragma mark -
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@implementation ByteParser
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- (instancetype)initWithData:(NSData *)data littleEndian:(BOOL)littleEndian
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{
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if (self = [super init]) {
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_littleEndian = littleEndian;
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_data = data;
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}
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return self;
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}
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#pragma mark - UInt16
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- (uint16_t)uint16AtIndex:(NSUInteger)index
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{
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uint16_t value;
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const size_t valueSize = sizeof(value);
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OWSAssertDebug(valueSize == 2);
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if (index + valueSize > self.data.length) {
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self.hasError = YES;
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return 0;
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}
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[self.data getBytes:&value range:NSMakeRange(index, valueSize)];
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if (self.littleEndian) {
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return CFSwapInt16LittleToHost(value);
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} else {
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return CFSwapInt16BigToHost(value);
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}
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}
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- (uint16_t)nextUInt16
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{
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uint16_t value = [self uint16AtIndex:self.cursor];
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self.cursor += sizeof(value);
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return value;
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}
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#pragma mark - UInt32
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- (uint32_t)uint32AtIndex:(NSUInteger)index
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{
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uint32_t value;
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const size_t valueSize = sizeof(value);
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OWSAssertDebug(valueSize == 4);
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if (index + valueSize > self.data.length) {
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self.hasError = YES;
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return 0;
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}
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[self.data getBytes:&value range:NSMakeRange(index, valueSize)];
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if (self.littleEndian) {
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return CFSwapInt32LittleToHost(value);
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} else {
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return CFSwapInt32BigToHost(value);
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}
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}
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- (uint32_t)nextUInt32
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{
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uint32_t value = [self uint32AtIndex:self.cursor];
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self.cursor += sizeof(value);
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return value;
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}
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#pragma mark - UInt64
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- (uint64_t)uint64AtIndex:(NSUInteger)index
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{
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uint64_t value;
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const size_t valueSize = sizeof(value);
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OWSAssertDebug(valueSize == 8);
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if (index + valueSize > self.data.length) {
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self.hasError = YES;
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return 0;
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}
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[self.data getBytes:&value range:NSMakeRange(index, valueSize)];
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if (self.littleEndian) {
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return CFSwapInt64LittleToHost(value);
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} else {
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return CFSwapInt64BigToHost(value);
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}
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}
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- (uint64_t)nextUInt64
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{
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uint64_t value = [self uint64AtIndex:self.cursor];
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self.cursor += sizeof(value);
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return value;
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}
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#pragma mark -
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- (BOOL)readZero:(NSUInteger)length
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{
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NSData *_Nullable subdata = [self readBytes:length];
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if (!subdata) {
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return NO;
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}
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uint8_t bytes[length];
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[subdata getBytes:bytes range:NSMakeRange(0, length)];
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for (int i = 0; i < length; i++) {
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if (bytes[i] != 0) {
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return NO;
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}
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}
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return YES;
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}
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- (nullable NSData *)readBytes:(NSUInteger)length
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{
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NSUInteger index = self.cursor;
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if (index + length > self.data.length) {
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self.hasError = YES;
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return nil;
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}
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NSData *_Nullable subdata = [self.data subdataWithRange:NSMakeRange(index, length)];
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self.cursor += length;
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return subdata;
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}
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@end
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NS_ASSUME_NONNULL_END
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