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GCDAsyncSocket.m
executable file
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GCDAsyncSocket.m
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//
// GCDAsyncSocket.m
//
// This class is in the public domain.
// Originally created by Robbie Hanson in Q4 2010.
// Updated and maintained by Deusty LLC and the Apple development community.
//
// https://github.com/robbiehanson/CocoaAsyncSocket
//
#import "GCDAsyncSocket.h"
#if TARGET_OS_IPHONE
#import <CFNetwork/CFNetwork.h>
#endif
#import <arpa/inet.h>
#import <fcntl.h>
#import <ifaddrs.h>
#import <netdb.h>
#import <netinet/in.h>
#import <net/if.h>
#import <sys/socket.h>
#import <sys/types.h>
#import <sys/ioctl.h>
#import <sys/poll.h>
#import <sys/uio.h>
#import <unistd.h>
#if ! __has_feature(objc_arc)
#warning This file must be compiled with ARC. Use -fobjc-arc flag (or convert project to ARC).
// For more information see: https://github.com/robbiehanson/CocoaAsyncSocket/wiki/ARC
#endif
/**
* Does ARC support support GCD objects?
* It does if the minimum deployment target is iOS 6+ or Mac OS X 10.8+
**/
#if TARGET_OS_IPHONE
// Compiling for iOS
#if __IPHONE_OS_VERSION_MIN_REQUIRED >= 60000 // iOS 6.0 or later
#define NEEDS_DISPATCH_RETAIN_RELEASE 0
#else // iOS 5.X or earlier
#define NEEDS_DISPATCH_RETAIN_RELEASE 1
#endif
#else
// Compiling for Mac OS X
#if MAC_OS_X_VERSION_MIN_REQUIRED >= 1080 // Mac OS X 10.8 or later
#define NEEDS_DISPATCH_RETAIN_RELEASE 0
#else
#define NEEDS_DISPATCH_RETAIN_RELEASE 1 // Mac OS X 10.7 or earlier
#endif
#endif
#if 0
// Logging Enabled - See log level below
// Logging uses the CocoaLumberjack framework (which is also GCD based).
// https://github.com/robbiehanson/CocoaLumberjack
//
// It allows us to do a lot of logging without significantly slowing down the code.
#import "DDLog.h"
#define LogAsync YES
#define LogContext 65535
#define LogObjc(flg, frmt, ...) LOG_OBJC_MAYBE(LogAsync, logLevel, flg, LogContext, frmt, ##__VA_ARGS__)
#define LogC(flg, frmt, ...) LOG_C_MAYBE(LogAsync, logLevel, flg, LogContext, frmt, ##__VA_ARGS__)
#define LogError(frmt, ...) LogObjc(LOG_FLAG_ERROR, (@"%@: " frmt), THIS_FILE, ##__VA_ARGS__)
#define LogWarn(frmt, ...) LogObjc(LOG_FLAG_WARN, (@"%@: " frmt), THIS_FILE, ##__VA_ARGS__)
#define LogInfo(frmt, ...) LogObjc(LOG_FLAG_INFO, (@"%@: " frmt), THIS_FILE, ##__VA_ARGS__)
#define LogVerbose(frmt, ...) LogObjc(LOG_FLAG_VERBOSE, (@"%@: " frmt), THIS_FILE, ##__VA_ARGS__)
#define LogCError(frmt, ...) LogC(LOG_FLAG_ERROR, (@"%@: " frmt), THIS_FILE, ##__VA_ARGS__)
#define LogCWarn(frmt, ...) LogC(LOG_FLAG_WARN, (@"%@: " frmt), THIS_FILE, ##__VA_ARGS__)
#define LogCInfo(frmt, ...) LogC(LOG_FLAG_INFO, (@"%@: " frmt), THIS_FILE, ##__VA_ARGS__)
#define LogCVerbose(frmt, ...) LogC(LOG_FLAG_VERBOSE, (@"%@: " frmt), THIS_FILE, ##__VA_ARGS__)
#define LogTrace() LogObjc(LOG_FLAG_VERBOSE, @"%@: %@", THIS_FILE, THIS_METHOD)
#define LogCTrace() LogC(LOG_FLAG_VERBOSE, @"%@: %s", THIS_FILE, __FUNCTION__)
// Log levels : off, error, warn, info, verbose
static const int logLevel = LOG_LEVEL_VERBOSE;
#else
// Logging Disabled
#define LogError(frmt, ...) {}
#define LogWarn(frmt, ...) {}
#define LogInfo(frmt, ...) {}
#define LogVerbose(frmt, ...) {}
#define LogCError(frmt, ...) {}
#define LogCWarn(frmt, ...) {}
#define LogCInfo(frmt, ...) {}
#define LogCVerbose(frmt, ...) {}
#define LogTrace() {}
#define LogCTrace(frmt, ...) {}
#endif
/**
* Seeing a return statements within an inner block
* can sometimes be mistaken for a return point of the enclosing method.
* This makes inline blocks a bit easier to read.
**/
#define return_from_block return
/**
* A socket file descriptor is really just an integer.
* It represents the index of the socket within the kernel.
* This makes invalid file descriptor comparisons easier to read.
**/
#define SOCKET_NULL -1
NSString *const GCDAsyncSocketException = @"GCDAsyncSocketException";
NSString *const GCDAsyncSocketErrorDomain = @"GCDAsyncSocketErrorDomain";
NSString *const GCDAsyncSocketQueueName = @"GCDAsyncSocket";
NSString *const GCDAsyncSocketThreadName = @"GCDAsyncSocket-CFStream";
#if SECURE_TRANSPORT_MAYBE_AVAILABLE
NSString *const GCDAsyncSocketSSLCipherSuites = @"GCDAsyncSocketSSLCipherSuites";
#if TARGET_OS_IPHONE
NSString *const GCDAsyncSocketSSLProtocolVersionMin = @"GCDAsyncSocketSSLProtocolVersionMin";
NSString *const GCDAsyncSocketSSLProtocolVersionMax = @"GCDAsyncSocketSSLProtocolVersionMax";
#else
NSString *const GCDAsyncSocketSSLDiffieHellmanParameters = @"GCDAsyncSocketSSLDiffieHellmanParameters";
#endif
#endif
enum GCDAsyncSocketFlags
{
kSocketStarted = 1 << 0, // If set, socket has been started (accepting/connecting)
kConnected = 1 << 1, // If set, the socket is connected
kForbidReadsWrites = 1 << 2, // If set, no new reads or writes are allowed
kReadsPaused = 1 << 3, // If set, reads are paused due to possible timeout
kWritesPaused = 1 << 4, // If set, writes are paused due to possible timeout
kDisconnectAfterReads = 1 << 5, // If set, disconnect after no more reads are queued
kDisconnectAfterWrites = 1 << 6, // If set, disconnect after no more writes are queued
kSocketCanAcceptBytes = 1 << 7, // If set, we know socket can accept bytes. If unset, it's unknown.
kReadSourceSuspended = 1 << 8, // If set, the read source is suspended
kWriteSourceSuspended = 1 << 9, // If set, the write source is suspended
kQueuedTLS = 1 << 10, // If set, we've queued an upgrade to TLS
kStartingReadTLS = 1 << 11, // If set, we're waiting for TLS negotiation to complete
kStartingWriteTLS = 1 << 12, // If set, we're waiting for TLS negotiation to complete
kSocketSecure = 1 << 13, // If set, socket is using secure communication via SSL/TLS
kSocketHasReadEOF = 1 << 14, // If set, we have read EOF from socket
kReadStreamClosed = 1 << 15, // If set, we've read EOF plus prebuffer has been drained
#if TARGET_OS_IPHONE
kAddedStreamsToRunLoop = 1 << 16, // If set, CFStreams have been added to listener thread
kUsingCFStreamForTLS = 1 << 17, // If set, we're forced to use CFStream instead of SecureTransport
kSecureSocketHasBytesAvailable = 1 << 18, // If set, CFReadStream has notified us of bytes available
#endif
};
enum GCDAsyncSocketConfig
{
kIPv4Disabled = 1 << 0, // If set, IPv4 is disabled
kIPv6Disabled = 1 << 1, // If set, IPv6 is disabled
kPreferIPv6 = 1 << 2, // If set, IPv6 is preferred over IPv4
kAllowHalfDuplexConnection = 1 << 3, // If set, the socket will stay open even if the read stream closes
};
#if TARGET_OS_IPHONE
static NSThread *cfstreamThread; // Used for CFStreams
#endif
@interface GCDAsyncSocket ()
{
uint32_t flags;
uint16_t config;
#if __has_feature(objc_arc_weak)
__weak id delegate;
#else
__unsafe_unretained id delegate;
#endif
dispatch_queue_t delegateQueue;
int socket4FD;
int socket6FD;
int connectIndex;
NSData * connectInterface4;
NSData * connectInterface6;
dispatch_queue_t socketQueue;
dispatch_source_t accept4Source;
dispatch_source_t accept6Source;
dispatch_source_t connectTimer;
dispatch_source_t readSource;
dispatch_source_t writeSource;
dispatch_source_t readTimer;
dispatch_source_t writeTimer;
NSMutableArray *readQueue;
NSMutableArray *writeQueue;
GCDAsyncReadPacket *currentRead;
GCDAsyncWritePacket *currentWrite;
unsigned long socketFDBytesAvailable;
GCDAsyncSocketPreBuffer *preBuffer;
#if TARGET_OS_IPHONE
CFStreamClientContext streamContext;
CFReadStreamRef readStream;
CFWriteStreamRef writeStream;
#endif
#if SECURE_TRANSPORT_MAYBE_AVAILABLE
SSLContextRef sslContext;
GCDAsyncSocketPreBuffer *sslPreBuffer;
size_t sslWriteCachedLength;
OSStatus sslErrCode;
#endif
void *IsOnSocketQueueOrTargetQueueKey;
id userData;
}
// Accepting
- (BOOL)doAccept:(int)socketFD;
// Connecting
- (void)startConnectTimeout:(NSTimeInterval)timeout;
- (void)endConnectTimeout;
- (void)doConnectTimeout;
- (void)lookup:(int)aConnectIndex host:(NSString *)host port:(uint16_t)port;
- (void)lookup:(int)aConnectIndex didSucceedWithAddress4:(NSData *)address4 address6:(NSData *)address6;
- (void)lookup:(int)aConnectIndex didFail:(NSError *)error;
- (BOOL)connectWithAddress4:(NSData *)address4 address6:(NSData *)address6 error:(NSError **)errPtr;
- (void)didConnect:(int)aConnectIndex;
- (void)didNotConnect:(int)aConnectIndex error:(NSError *)error;
// Disconnect
- (void)closeWithError:(NSError *)error;
- (void)maybeClose;
// Errors
- (NSError *)badConfigError:(NSString *)msg;
- (NSError *)badParamError:(NSString *)msg;
- (NSError *)gaiError:(int)gai_error;
- (NSError *)errnoError;
- (NSError *)errnoErrorWithReason:(NSString *)reason;
- (NSError *)connectTimeoutError;
- (NSError *)otherError:(NSString *)msg;
// Diagnostics
- (NSString *)connectedHost4;
- (NSString *)connectedHost6;
- (uint16_t)connectedPort4;
- (uint16_t)connectedPort6;
- (NSString *)localHost4;
- (NSString *)localHost6;
- (uint16_t)localPort4;
- (uint16_t)localPort6;
- (NSString *)connectedHostFromSocket4:(int)socketFD;
- (NSString *)connectedHostFromSocket6:(int)socketFD;
- (uint16_t)connectedPortFromSocket4:(int)socketFD;
- (uint16_t)connectedPortFromSocket6:(int)socketFD;
- (NSString *)localHostFromSocket4:(int)socketFD;
- (NSString *)localHostFromSocket6:(int)socketFD;
- (uint16_t)localPortFromSocket4:(int)socketFD;
- (uint16_t)localPortFromSocket6:(int)socketFD;
// Utilities
- (void)getInterfaceAddress4:(NSMutableData **)addr4Ptr
address6:(NSMutableData **)addr6Ptr
fromDescription:(NSString *)interfaceDescription
port:(uint16_t)port;
- (void)setupReadAndWriteSourcesForNewlyConnectedSocket:(int)socketFD;
- (void)suspendReadSource;
- (void)resumeReadSource;
- (void)suspendWriteSource;
- (void)resumeWriteSource;
// Reading
- (void)maybeDequeueRead;
- (void)flushSSLBuffers;
- (void)doReadData;
- (void)doReadEOF;
- (void)completeCurrentRead;
- (void)endCurrentRead;
- (void)setupReadTimerWithTimeout:(NSTimeInterval)timeout;
- (void)doReadTimeout;
- (void)doReadTimeoutWithExtension:(NSTimeInterval)timeoutExtension;
// Writing
- (void)maybeDequeueWrite;
- (void)doWriteData;
- (void)completeCurrentWrite;
- (void)endCurrentWrite;
- (void)setupWriteTimerWithTimeout:(NSTimeInterval)timeout;
- (void)doWriteTimeout;
- (void)doWriteTimeoutWithExtension:(NSTimeInterval)timeoutExtension;
// Security
- (void)maybeStartTLS;
#if SECURE_TRANSPORT_MAYBE_AVAILABLE
- (void)ssl_startTLS;
- (void)ssl_continueSSLHandshake;
#endif
#if TARGET_OS_IPHONE
- (void)cf_startTLS;
#endif
// CFStream
#if TARGET_OS_IPHONE
+ (void)startCFStreamThreadIfNeeded;
- (BOOL)createReadAndWriteStream;
- (BOOL)registerForStreamCallbacksIncludingReadWrite:(BOOL)includeReadWrite;
- (BOOL)addStreamsToRunLoop;
- (BOOL)openStreams;
- (void)removeStreamsFromRunLoop;
#endif
// Class Methods
+ (NSString *)hostFromSockaddr4:(const struct sockaddr_in *)pSockaddr4;
+ (NSString *)hostFromSockaddr6:(const struct sockaddr_in6 *)pSockaddr6;
+ (uint16_t)portFromSockaddr4:(const struct sockaddr_in *)pSockaddr4;
+ (uint16_t)portFromSockaddr6:(const struct sockaddr_in6 *)pSockaddr6;
@end
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
#pragma mark -
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
/**
* A PreBuffer is used when there is more data available on the socket
* than is being requested by current read request.
* In this case we slurp up all data from the socket (to minimize sys calls),
* and store additional yet unread data in a "prebuffer".
*
* The prebuffer is entirely drained before we read from the socket again.
* In other words, a large chunk of data is written is written to the prebuffer.
* The prebuffer is then drained via a series of one or more reads (for subsequent read request(s)).
*
* A ring buffer was once used for this purpose.
* But a ring buffer takes up twice as much memory as needed (double the size for mirroring).
* In fact, it generally takes up more than twice the needed size as everything has to be rounded up to vm_page_size.
* And since the prebuffer is always completely drained after being written to, a full ring buffer isn't needed.
*
* The current design is very simple and straight-forward, while also keeping memory requirements lower.
**/
@interface GCDAsyncSocketPreBuffer : NSObject
{
uint8_t *preBuffer;
size_t preBufferSize;
uint8_t *readPointer;
uint8_t *writePointer;
}
- (id)initWithCapacity:(size_t)numBytes;
- (void)ensureCapacityForWrite:(size_t)numBytes;
- (size_t)availableBytes;
- (uint8_t *)readBuffer;
- (void)getReadBuffer:(uint8_t **)bufferPtr availableBytes:(size_t *)availableBytesPtr;
- (size_t)availableSpace;
- (uint8_t *)writeBuffer;
- (void)getWriteBuffer:(uint8_t **)bufferPtr availableSpace:(size_t *)availableSpacePtr;
- (void)didRead:(size_t)bytesRead;
- (void)didWrite:(size_t)bytesWritten;
- (void)reset;
@end
@implementation GCDAsyncSocketPreBuffer
- (id)initWithCapacity:(size_t)numBytes
{
if ((self = [super init]))
{
preBufferSize = numBytes;
preBuffer = malloc(preBufferSize);
readPointer = preBuffer;
writePointer = preBuffer;
}
return self;
}
- (void)dealloc
{
if (preBuffer)
free(preBuffer);
}
- (void)ensureCapacityForWrite:(size_t)numBytes
{
size_t availableSpace = preBufferSize - (writePointer - readPointer);
if (numBytes > availableSpace)
{
size_t additionalBytes = numBytes - availableSpace;
size_t newPreBufferSize = preBufferSize + additionalBytes;
uint8_t *newPreBuffer = realloc(preBuffer, newPreBufferSize);
size_t readPointerOffset = readPointer - preBuffer;
size_t writePointerOffset = writePointer - preBuffer;
preBuffer = newPreBuffer;
preBufferSize = newPreBufferSize;
readPointer = preBuffer + readPointerOffset;
writePointer = preBuffer + writePointerOffset;
}
}
- (size_t)availableBytes
{
return writePointer - readPointer;
}
- (uint8_t *)readBuffer
{
return readPointer;
}
- (void)getReadBuffer:(uint8_t **)bufferPtr availableBytes:(size_t *)availableBytesPtr
{
if (bufferPtr) *bufferPtr = readPointer;
if (availableBytesPtr) *availableBytesPtr = writePointer - readPointer;
}
- (void)didRead:(size_t)bytesRead
{
readPointer += bytesRead;
if (readPointer == writePointer)
{
// The prebuffer has been drained. Reset pointers.
readPointer = preBuffer;
writePointer = preBuffer;
}
}
- (size_t)availableSpace
{
return preBufferSize - (writePointer - readPointer);
}
- (uint8_t *)writeBuffer
{
return writePointer;
}
- (void)getWriteBuffer:(uint8_t **)bufferPtr availableSpace:(size_t *)availableSpacePtr
{
if (bufferPtr) *bufferPtr = writePointer;
if (availableSpacePtr) *availableSpacePtr = preBufferSize - (writePointer - readPointer);
}
- (void)didWrite:(size_t)bytesWritten
{
writePointer += bytesWritten;
}
- (void)reset
{
readPointer = preBuffer;
writePointer = preBuffer;
}
@end
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
#pragma mark -
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
/**
* The GCDAsyncReadPacket encompasses the instructions for any given read.
* The content of a read packet allows the code to determine if we're:
* - reading to a certain length
* - reading to a certain separator
* - or simply reading the first chunk of available data
**/
@interface GCDAsyncReadPacket : NSObject
{
@public
NSMutableData *buffer;
NSUInteger startOffset;
NSUInteger bytesDone;
NSUInteger maxLength;
NSTimeInterval timeout;
NSUInteger readLength;
NSData *term;
BOOL bufferOwner;
NSUInteger originalBufferLength;
long tag;
}
- (id)initWithData:(NSMutableData *)d
startOffset:(NSUInteger)s
maxLength:(NSUInteger)m
timeout:(NSTimeInterval)t
readLength:(NSUInteger)l
terminator:(NSData *)e
tag:(long)i;
- (void)ensureCapacityForAdditionalDataOfLength:(NSUInteger)bytesToRead;
- (NSUInteger)optimalReadLengthWithDefault:(NSUInteger)defaultValue shouldPreBuffer:(BOOL *)shouldPreBufferPtr;
- (NSUInteger)readLengthForNonTermWithHint:(NSUInteger)bytesAvailable;
- (NSUInteger)readLengthForTermWithHint:(NSUInteger)bytesAvailable shouldPreBuffer:(BOOL *)shouldPreBufferPtr;
- (NSUInteger)readLengthForTermWithPreBuffer:(GCDAsyncSocketPreBuffer *)preBuffer found:(BOOL *)foundPtr;
- (NSInteger)searchForTermAfterPreBuffering:(ssize_t)numBytes;
@end
@implementation GCDAsyncReadPacket
- (id)initWithData:(NSMutableData *)d
startOffset:(NSUInteger)s
maxLength:(NSUInteger)m
timeout:(NSTimeInterval)t
readLength:(NSUInteger)l
terminator:(NSData *)e
tag:(long)i
{
if((self = [super init]))
{
bytesDone = 0;
maxLength = m;
timeout = t;
readLength = l;
term = [e copy];
tag = i;
if (d)
{
buffer = d;
startOffset = s;
bufferOwner = NO;
originalBufferLength = [d length];
}
else
{
if (readLength > 0)
buffer = [[NSMutableData alloc] initWithLength:readLength];
else
buffer = [[NSMutableData alloc] initWithLength:0];
startOffset = 0;
bufferOwner = YES;
originalBufferLength = 0;
}
}
return self;
}
/**
* Increases the length of the buffer (if needed) to ensure a read of the given size will fit.
**/
- (void)ensureCapacityForAdditionalDataOfLength:(NSUInteger)bytesToRead
{
NSUInteger buffSize = [buffer length];
NSUInteger buffUsed = startOffset + bytesDone;
NSUInteger buffSpace = buffSize - buffUsed;
if (bytesToRead > buffSpace)
{
NSUInteger buffInc = bytesToRead - buffSpace;
[buffer increaseLengthBy:buffInc];
}
}
/**
* This method is used when we do NOT know how much data is available to be read from the socket.
* This method returns the default value unless it exceeds the specified readLength or maxLength.
*
* Furthermore, the shouldPreBuffer decision is based upon the packet type,
* and whether the returned value would fit in the current buffer without requiring a resize of the buffer.
**/
- (NSUInteger)optimalReadLengthWithDefault:(NSUInteger)defaultValue shouldPreBuffer:(BOOL *)shouldPreBufferPtr
{
NSUInteger result;
if (readLength > 0)
{
// Read a specific length of data
result = MIN(defaultValue, (readLength - bytesDone));
// There is no need to prebuffer since we know exactly how much data we need to read.
// Even if the buffer isn't currently big enough to fit this amount of data,
// it would have to be resized eventually anyway.
if (shouldPreBufferPtr)
*shouldPreBufferPtr = NO;
}
else
{
// Either reading until we find a specified terminator,
// or we're simply reading all available data.
//
// In other words, one of:
//
// - readDataToData packet
// - readDataWithTimeout packet
if (maxLength > 0)
result = MIN(defaultValue, (maxLength - bytesDone));
else
result = defaultValue;
// Since we don't know the size of the read in advance,
// the shouldPreBuffer decision is based upon whether the returned value would fit
// in the current buffer without requiring a resize of the buffer.
//
// This is because, in all likelyhood, the amount read from the socket will be less than the default value.
// Thus we should avoid over-allocating the read buffer when we can simply use the pre-buffer instead.
if (shouldPreBufferPtr)
{
NSUInteger buffSize = [buffer length];
NSUInteger buffUsed = startOffset + bytesDone;
NSUInteger buffSpace = buffSize - buffUsed;
if (buffSpace >= result)
*shouldPreBufferPtr = NO;
else
*shouldPreBufferPtr = YES;
}
}
return result;
}
/**
* For read packets without a set terminator, returns the amount of data
* that can be read without exceeding the readLength or maxLength.
*
* The given parameter indicates the number of bytes estimated to be available on the socket,
* which is taken into consideration during the calculation.
*
* The given hint MUST be greater than zero.
**/
- (NSUInteger)readLengthForNonTermWithHint:(NSUInteger)bytesAvailable
{
NSAssert(term == nil, @"This method does not apply to term reads");
NSAssert(bytesAvailable > 0, @"Invalid parameter: bytesAvailable");
if (readLength > 0)
{
// Read a specific length of data
return MIN(bytesAvailable, (readLength - bytesDone));
// No need to avoid resizing the buffer.
// If the user provided their own buffer,
// and told us to read a certain length of data that exceeds the size of the buffer,
// then it is clear that our code will resize the buffer during the read operation.
//
// This method does not actually do any resizing.
// The resizing will happen elsewhere if needed.
}
else
{
// Read all available data
NSUInteger result = bytesAvailable;
if (maxLength > 0)
{
result = MIN(result, (maxLength - bytesDone));
}
// No need to avoid resizing the buffer.
// If the user provided their own buffer,
// and told us to read all available data without giving us a maxLength,
// then it is clear that our code might resize the buffer during the read operation.
//
// This method does not actually do any resizing.
// The resizing will happen elsewhere if needed.
return result;
}
}
/**
* For read packets with a set terminator, returns the amount of data
* that can be read without exceeding the maxLength.
*
* The given parameter indicates the number of bytes estimated to be available on the socket,
* which is taken into consideration during the calculation.
*
* To optimize memory allocations, mem copies, and mem moves
* the shouldPreBuffer boolean value will indicate if the data should be read into a prebuffer first,
* or if the data can be read directly into the read packet's buffer.
**/
- (NSUInteger)readLengthForTermWithHint:(NSUInteger)bytesAvailable shouldPreBuffer:(BOOL *)shouldPreBufferPtr
{
NSAssert(term != nil, @"This method does not apply to non-term reads");
NSAssert(bytesAvailable > 0, @"Invalid parameter: bytesAvailable");
NSUInteger result = bytesAvailable;
if (maxLength > 0)
{
result = MIN(result, (maxLength - bytesDone));
}
// Should the data be read into the read packet's buffer, or into a pre-buffer first?
//
// One would imagine the preferred option is the faster one.
// So which one is faster?
//
// Reading directly into the packet's buffer requires:
// 1. Possibly resizing packet buffer (malloc/realloc)
// 2. Filling buffer (read)
// 3. Searching for term (memcmp)
// 4. Possibly copying overflow into prebuffer (malloc/realloc, memcpy)
//
// Reading into prebuffer first:
// 1. Possibly resizing prebuffer (malloc/realloc)
// 2. Filling buffer (read)
// 3. Searching for term (memcmp)
// 4. Copying underflow into packet buffer (malloc/realloc, memcpy)
// 5. Removing underflow from prebuffer (memmove)
//
// Comparing the performance of the two we can see that reading
// data into the prebuffer first is slower due to the extra memove.
//
// However:
// The implementation of NSMutableData is open source via core foundation's CFMutableData.
// Decreasing the length of a mutable data object doesn't cause a realloc.
// In other words, the capacity of a mutable data object can grow, but doesn't shrink.
//
// This means the prebuffer will rarely need a realloc.
// The packet buffer, on the other hand, may often need a realloc.
// This is especially true if we are the buffer owner.
// Furthermore, if we are constantly realloc'ing the packet buffer,
// and then moving the overflow into the prebuffer,
// then we're consistently over-allocating memory for each term read.
// And now we get into a bit of a tradeoff between speed and memory utilization.
//
// The end result is that the two perform very similarly.
// And we can answer the original question very simply by another means.
//
// If we can read all the data directly into the packet's buffer without resizing it first,
// then we do so. Otherwise we use the prebuffer.
if (shouldPreBufferPtr)
{
NSUInteger buffSize = [buffer length];
NSUInteger buffUsed = startOffset + bytesDone;
if ((buffSize - buffUsed) >= result)
*shouldPreBufferPtr = NO;
else
*shouldPreBufferPtr = YES;
}
return result;
}
/**
* For read packets with a set terminator,
* returns the amount of data that can be read from the given preBuffer,
* without going over a terminator or the maxLength.
*
* It is assumed the terminator has not already been read.
**/
- (NSUInteger)readLengthForTermWithPreBuffer:(GCDAsyncSocketPreBuffer *)preBuffer found:(BOOL *)foundPtr
{
NSAssert(term != nil, @"This method does not apply to non-term reads");
NSAssert([preBuffer availableBytes] > 0, @"Invoked with empty pre buffer!");
// We know that the terminator, as a whole, doesn't exist in our own buffer.
// But it is possible that a _portion_ of it exists in our buffer.
// So we're going to look for the terminator starting with a portion of our own buffer.
//
// Example:
//
// term length = 3 bytes
// bytesDone = 5 bytes
// preBuffer length = 5 bytes
//
// If we append the preBuffer to our buffer,
// it would look like this:
//
// ---------------------
// |B|B|B|B|B|P|P|P|P|P|
// ---------------------
//
// So we start our search here:
//
// ---------------------
// |B|B|B|B|B|P|P|P|P|P|
// -------^-^-^---------
//
// And move forwards...
//
// ---------------------
// |B|B|B|B|B|P|P|P|P|P|
// ---------^-^-^-------
//
// Until we find the terminator or reach the end.
//
// ---------------------
// |B|B|B|B|B|P|P|P|P|P|
// ---------------^-^-^-
BOOL found = NO;
NSUInteger termLength = [term length];
NSUInteger preBufferLength = [preBuffer availableBytes];
if ((bytesDone + preBufferLength) < termLength)
{
// Not enough data for a full term sequence yet
return preBufferLength;
}
NSUInteger maxPreBufferLength;
if (maxLength > 0) {
maxPreBufferLength = MIN(preBufferLength, (maxLength - bytesDone));
// Note: maxLength >= termLength
}
else {
maxPreBufferLength = preBufferLength;
}
uint8_t seq[termLength];
const void *termBuf = [term bytes];
NSUInteger bufLen = MIN(bytesDone, (termLength - 1));
uint8_t *buf = (uint8_t *)[buffer mutableBytes] + startOffset + bytesDone - bufLen;
NSUInteger preLen = termLength - bufLen;
const uint8_t *pre = [preBuffer readBuffer];
NSUInteger loopCount = bufLen + maxPreBufferLength - termLength + 1; // Plus one. See example above.
NSUInteger result = maxPreBufferLength;
NSUInteger i;
for (i = 0; i < loopCount; i++)
{
if (bufLen > 0)
{
// Combining bytes from buffer and preBuffer
memcpy(seq, buf, bufLen);
memcpy(seq + bufLen, pre, preLen);
if (memcmp(seq, termBuf, termLength) == 0)
{
result = preLen;
found = YES;
break;
}
buf++;
bufLen--;
preLen++;
}
else
{
// Comparing directly from preBuffer
if (memcmp(pre, termBuf, termLength) == 0)
{
NSUInteger preOffset = pre - [preBuffer readBuffer]; // pointer arithmetic
result = preOffset + termLength;
found = YES;
break;
}
pre++;
}
}
// There is no need to avoid resizing the buffer in this particular situation.
if (foundPtr) *foundPtr = found;
return result;
}
/**
* For read packets with a set terminator, scans the packet buffer for the term.
* It is assumed the terminator had not been fully read prior to the new bytes.
*
* If the term is found, the number of excess bytes after the term are returned.
* If the term is not found, this method will return -1.
*
* Note: A return value of zero means the term was found at the very end.
*
* Prerequisites:
* The given number of bytes have been added to the end of our buffer.
* Our bytesDone variable has NOT been changed due to the prebuffered bytes.
**/
- (NSInteger)searchForTermAfterPreBuffering:(ssize_t)numBytes
{
NSAssert(term != nil, @"This method does not apply to non-term reads");
// The implementation of this method is very similar to the above method.
// See the above method for a discussion of the algorithm used here.
uint8_t *buff = [buffer mutableBytes];
NSUInteger buffLength = bytesDone + numBytes;
const void *termBuff = [term bytes];
NSUInteger termLength = [term length];
// Note: We are dealing with unsigned integers,
// so make sure the math doesn't go below zero.
NSUInteger i = ((buffLength - numBytes) >= termLength) ? (buffLength - numBytes - termLength + 1) : 0;
while (i + termLength <= buffLength)
{
uint8_t *subBuffer = buff + startOffset + i;
if (memcmp(subBuffer, termBuff, termLength) == 0)
{
return buffLength - (i + termLength);
}
i++;
}
return -1;
}
@end
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
#pragma mark -
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
/**
* The GCDAsyncWritePacket encompasses the instructions for any given write.
**/
@interface GCDAsyncWritePacket : NSObject
{
@public
NSData *buffer;
NSUInteger bytesDone;
long tag;
NSTimeInterval timeout;
}
- (id)initWithData:(NSData *)d timeout:(NSTimeInterval)t tag:(long)i;
@end
@implementation GCDAsyncWritePacket
- (id)initWithData:(NSData *)d timeout:(NSTimeInterval)t tag:(long)i
{
if((self = [super init]))
{
buffer = d; // Retain not copy. For performance as documented in header file.
bytesDone = 0;
timeout = t;
tag = i;
}
return self;
}
@end
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
#pragma mark -
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
/**