libs-base/Source/GSStream.m

/** Implementation for GSStream for GNUStep
   Copyright (C) 2006 Free Software Foundation, Inc.

   Written by:  Derek Zhou <derekzhou@gmail.com>
   Written by:  Richard Frith-Macdonald <rfm@gnu.org>
   Date: 2006

   This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library General Public
   License as published by the Free Software Foundation; either
   version 2 of the License, or (at your option) any later version.

   This library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public
   License along with this library; if not, write to the Free
   Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
   Boston, MA 02111 USA.

   */
#include <unistd.h>
#include <errno.h>

#include <Foundation/NSData.h>
#include <Foundation/NSArray.h>
#include <Foundation/NSRunLoop.h>
#include <Foundation/NSException.h>
#include <Foundation/NSValue.h>
#include <Foundation/NSHost.h>
#include <Foundation/NSDebug.h>

#include "GSStream.h"
#include "GSPrivate.h"

NSString * const NSStreamDataWrittenToMemoryStreamKey
  = @"NSStreamDataWrittenToMemoryStreamKey";
NSString * const NSStreamFileCurrentOffsetKey
  = @"NSStreamFileCurrentOffsetKey";

NSString * const NSStreamSocketSecurityLevelKey
  = @"NSStreamSocketSecurityLevelKey";
NSString * const NSStreamSocketSecurityLevelNone
  = @"NSStreamSocketSecurityLevelNone";
NSString * const NSStreamSocketSecurityLevelSSLv2
  = @"NSStreamSocketSecurityLevelSSLv2";
NSString * const NSStreamSocketSecurityLevelSSLv3
  = @"NSStreamSocketSecurityLevelSSLv3";
NSString * const NSStreamSocketSecurityLevelTLSv1
  = @"NSStreamSocketSecurityLevelTLSv1";
NSString * const NSStreamSocketSecurityLevelNegotiatedSSL
  = @"NSStreamSocketSecurityLevelNegotiatedSSL";
NSString * const NSStreamSocketSSLErrorDomain
  = @"NSStreamSocketSSLErrorDomain";
NSString * const NSStreamSOCKSErrorDomain
  = @"NSStreamSOCKSErrorDomain";
NSString * const NSStreamSOCKSProxyConfigurationKey
  = @"NSStreamSOCKSProxyConfigurationKey";
NSString * const NSStreamSOCKSProxyHostKey
  = @"NSStreamSOCKSProxyHostKey";
NSString * const NSStreamSOCKSProxyPasswordKey
  = @"NSStreamSOCKSProxyPasswordKey";
NSString * const NSStreamSOCKSProxyPortKey
  = @"NSStreamSOCKSProxyPortKey";
NSString * const NSStreamSOCKSProxyUserKey
  = @"NSStreamSOCKSProxyUserKey";
NSString * const NSStreamSOCKSProxyVersion4
  = @"NSStreamSOCKSProxyVersion4";
NSString * const NSStreamSOCKSProxyVersion5
  = @"NSStreamSOCKSProxyVersion5";
NSString * const NSStreamSOCKSProxyVersionKey
  = @"NSStreamSOCKSProxyVersionKey";


/*
 * Determine the type of event to use when adding a stream to the run loop.
 * By default add as an 'ET_TRIGGER' so that the stream will be notified
 * every time the loop runs (the event id/reference must be the address of
 * the stream itsself to ensure that event/type is unique).
 *
 * Streams which actually expect to wait for I/O events must be added with
 * the appropriate information for the loop to signal them.
 */
static RunLoopEventType typeForStream(NSStream *aStream)
{
#if	defined(__MINGW32__)
  if ([aStream _loopID] == (void*)aStream)
    {
      return ET_TRIGGER;
    }
  else
    {
      return ET_HANDLE;
    }
#else
  if ([aStream _loopID] == (void*)aStream)
    {
      return ET_TRIGGER;
    }
  else if ([aStream isKindOfClass: [NSOutputStream class]] == NO
    && [aStream  streamStatus] != NSStreamStatusOpening)
    {
      return ET_RDESC;
    }
  else
    {
      return ET_WDESC;	
    }
#endif
}

@implementation	NSRunLoop (NSStream)
- (void) addStream: (NSStream*)aStream mode: (NSString*)mode
{
  [self addEvent: [aStream _loopID]
	    type: typeForStream(aStream)
	 watcher: (id<RunLoopEvents>)aStream
	 forMode: mode];
}

- (void) removeStream: (NSStream*)aStream mode: (NSString*)mode
{
  [self removeEvent: [aStream _loopID]
	       type: typeForStream(aStream)
	    forMode: mode
		all: NO];
}
@end

@implementation GSStream

- (void) close
{
  if (_currentStatus == NSStreamStatusNotOpen)
    {
      NSDebugMLog(@"Attempt to close unopened stream %@", self);
    }
  if (_currentStatus == NSStreamStatusClosed)
    {
      NSDebugMLog(@"Attempt to close already closed stream %@", self);
    }
  if (_runloop)
    {
      unsigned	i = [_modes count];

      while (i-- > 0)
	{
	  [_runloop removeStream: self mode: [_modes objectAtIndex: i]];
	}
    }
  [self _setStatus: NSStreamStatusClosed];
  /* We don't want to send any events the the delegate after the
   * stream has been closed.
   */
  _delegateValid = NO;
}

- (void) dealloc
{
  if (_currentStatus != NSStreamStatusNotOpen
    && _currentStatus != NSStreamStatusClosed)
    {
      [self close];
    }
  DESTROY(_runloop);
  DESTROY(_modes);
  DESTROY(_properties);
  DESTROY(_lastError);
  [super dealloc];
}

- (id) delegate
{
  return _delegate;
}

- (id) init
{
  if ((self = [super init]) != nil)
    {
      _delegate = self;
      _properties = nil;
      _lastError = nil;
      _modes = [NSMutableArray new];
      _currentStatus = NSStreamStatusNotOpen;
      _loopID = (void*)self;
    }
  return self;
}

- (void) open
{
  if (_currentStatus != NSStreamStatusNotOpen)
    {
      NSDebugMLog(@"Attempt to re-open stream %@", self);
    }
  [self _setStatus: NSStreamStatusOpen];
  if (_runloop)
    {
      unsigned	i = [_modes count];

      while (i-- > 0)
	{
	  [_runloop addStream: self mode: [_modes objectAtIndex: i]];
	}
    }
  [self _sendEvent: NSStreamEventOpenCompleted];
}

- (id) propertyForKey: (NSString *)key
{
  return [_properties objectForKey: key];
}

- (void) receivedEvent: (void*)data
                  type: (RunLoopEventType)type
		 extra: (void*)extra
	       forMode: (NSString*)mode
{
  [self _dispatch];
}

- (void) removeFromRunLoop: (NSRunLoop *)aRunLoop forMode: (NSString *)mode
{
  if (_runloop == aRunLoop)
    {
      if ([_modes containsObject: mode])
	{
	  if ([self _isOpened])
	    {
	      [_runloop removeStream: self mode: mode];
	    }
	  [_modes removeObject: mode];
	  if ([_modes count] == 0)
	    {
	      DESTROY(_runloop);
	    }
	}
    }
}

- (void) scheduleInRunLoop: (NSRunLoop *)aRunLoop forMode: (NSString *)mode
{
  NSAssert(!_runloop || _runloop == aRunLoop, 
    @"Attempt to schedule in more than one runloop.");
  ASSIGN(_runloop, aRunLoop);
  if ([_modes containsObject: mode] == NO)
    {
      mode = [mode copy];
      [_modes addObject: mode];
      RELEASE(mode);
      if ([self _isOpened])
	{
	  [_runloop addStream: self mode: mode];
	}
    }
}

- (void) setDelegate: (id)delegate
{
  if (delegate)
    {
      _delegate = delegate;
    }
  else
    {
      _delegate = self;
    }
  if ([self streamStatus] != NSStreamStatusClosed
    && [self streamStatus] != NSStreamStatusError)
    {
      /* We don't want to send any events the the delegate after the
       * stream has been closed.
       */
      _delegateValid
        = [_delegate respondsToSelector: @selector(stream:handleEvent:)];
    }
}

- (BOOL) setProperty: (id)property forKey: (NSString *)key
{
  if (_properties == nil)
    {
      _properties = [NSMutableDictionary new];
    }
  [_properties setObject: property forKey: key];
  return YES;
}

- (NSError *) streamError
{
  return _lastError;
}

- (NSStreamStatus) streamStatus
{
  return _currentStatus;
}

@end


@implementation	NSStream (Private)

- (void) _dispatch
{
}

- (BOOL) _isOpened
{
  return NO;
}

- (void*) _loopID
{
  return (void*)self;	// By default a stream is a TRIGGER event.
}

- (void) _recordError
{
}

- (void) _sendEvent: (NSStreamEvent)event
{
}

- (void) _setLoopID: (void *)ref
{
}

- (void) _setStatus: (NSStreamStatus)newStatus
{
}

- (BOOL) _unhandledData
{
  return NO;
}
@end

@implementation	GSStream (Private)

- (BOOL) _isOpened
{
  return !(_currentStatus == NSStreamStatusNotOpen
    || _currentStatus == NSStreamStatusOpening
    || _currentStatus == NSStreamStatusClosed);
}

- (void*) _loopID
{
  return _loopID;
}

- (void) _recordError
{
  NSError *theError;

#if	defined(__MINGW32__)
  errno = GetLastError();
#endif
  theError = [NSError errorWithDomain: NSPOSIXErrorDomain
					  code: errno
				      userInfo: nil];
  NSLog(@"%@ error(%d): - %@", self, errno, [NSError _last]);
  ASSIGN(_lastError, theError);
  _currentStatus = NSStreamStatusError;
}

- (void) _sendEvent: (NSStreamEvent)event
{
  if (event == NSStreamEventNone)
    {
      return;
    }
  else if (event == NSStreamEventOpenCompleted)
    {
      if ((_events & event) == 0)
	{
	  _events |= NSStreamEventOpenCompleted;
	  if (_delegateValid == YES)
	    {
	      [_delegate stream: self
		    handleEvent: NSStreamEventOpenCompleted];
	    }
	}
    }
  else if (event == NSStreamEventHasBytesAvailable)
    {
      if ((_events & NSStreamEventOpenCompleted) == 0)
	{
	  _events |= NSStreamEventOpenCompleted;
	  if (_delegateValid == YES)
	    {
	      [_delegate stream: self
		    handleEvent: NSStreamEventOpenCompleted];
	    }
	}
      if ((_events & NSStreamEventHasBytesAvailable) == 0)
	{
	  _events |= NSStreamEventHasBytesAvailable;
	  if (_delegateValid == YES)
	    {
	      [_delegate stream: self
		    handleEvent: NSStreamEventHasBytesAvailable];
	    }
	}
    }
  else if (event == NSStreamEventHasSpaceAvailable)
    {
      if ((_events & NSStreamEventOpenCompleted) == 0)
	{
	  _events |= NSStreamEventOpenCompleted;
	  if (_delegateValid == YES)
	    {
	      [_delegate stream: self
		    handleEvent: NSStreamEventOpenCompleted];
	    }
	}
      if ((_events & NSStreamEventHasSpaceAvailable) == 0)
	{
	  _events |= NSStreamEventHasSpaceAvailable;
	  if (_delegateValid == YES)
	    {
	      [_delegate stream: self
		    handleEvent: NSStreamEventHasSpaceAvailable];
	    }
	}
    }
  else if (event == NSStreamEventErrorOccurred)
    {
      if ((_events & NSStreamEventErrorOccurred) == 0)
	{
	  _events |= NSStreamEventErrorOccurred;
	  if (_delegateValid == YES)
	    {
	      [_delegate stream: self
		    handleEvent: NSStreamEventErrorOccurred];
	    }
	}
    }
  else if (event == NSStreamEventEndEncountered)
    {
      if ((_events & NSStreamEventEndEncountered) == 0)
	{
	  _events |= NSStreamEventEndEncountered;
	  if (_delegateValid == YES)
	    {
	      [_delegate stream: self
		    handleEvent: NSStreamEventEndEncountered];
	    }
	}
    }
  else
    {
      [NSException raise: NSInvalidArgumentException
		  format: @"Unknown event (%d) passed to _sendEvent:", event];
    }
}

- (void) _setLoopID: (void *)ref
{
  _loopID = ref;
}

- (void) _setStatus: (NSStreamStatus)newStatus
{
  _currentStatus = newStatus;
}

- (BOOL) _unhandledData
{
  if (_events
    & (NSStreamEventHasBytesAvailable | NSStreamEventHasSpaceAvailable))
    {
      return YES;
    }
  return NO;
}

- (BOOL) runLoopShouldBlock: (BOOL*)trigger
{
  if (_events
    & (NSStreamEventHasBytesAvailable | NSStreamEventHasSpaceAvailable))
    {
      /* If we have an unhandled data event, we should not watch for more
       * or trigger until the appropriate read or write has been done.
       */
      *trigger = NO;
      return NO;
    }
  if (_currentStatus == NSStreamStatusError &&
    (_events & NSStreamEventErrorOccurred) == NSStreamEventErrorOccurred)
    {
      /* If an error has occurred (and been handled),
       * we should not watch for any events at all.
       */
      *trigger = NO;
      return NO;
    }
  if (_currentStatus == NSStreamStatusAtEnd &&
    (_events & NSStreamEventEndEncountered) == NSStreamEventEndEncountered)
    {
      /* If an error has occurred (and been handled),
       * we should not watch for any events at all.
       */
      *trigger = NO;
      return NO;
    }

  if (_loopID == (void*)self)
    {
      /* If _loopID is the receiver, the stream is not receiving external
       * input, so it must trigger an event when the loop runs and must not
       * block the loop from running.
       */
      *trigger = YES;
      return NO;
    }
  else
    {
      *trigger = YES;
      return YES;
    }
}
@end

@implementation	GSInputStream

+ (void) initialize
{
  if (self == [GSInputStream class])
    {
      GSObjCAddClassBehavior(self, [GSStream class]);
    }
}

- (BOOL) hasBytesAvailable
{
  if (_currentStatus == NSStreamStatusOpen)
    {
      return YES;
    }
  if (_currentStatus == NSStreamStatusAtEnd)
    {
      if ((_events & NSStreamEventEndEncountered) == 0)
	{
	  /* We have not sent the appropriate event yet, so the
           * client must not have issued a read:maxLength:
	   * (which is the point at which we should send).
	   */
	  return YES;
	}
    }
  return NO;
}

@end

@implementation	GSOutputStream

+ (void) initialize
{
  if (self == [GSOutputStream class])
    {
      GSObjCAddClassBehavior(self, [GSStream class]);
    }
}

- (BOOL) hasSpaceAvailable
{
  if (_currentStatus == NSStreamStatusOpen)
    {
      return YES;
    }
  if (_currentStatus == NSStreamStatusAtEnd)
    {
      if ((_events & NSStreamEventEndEncountered) == 0)
	{
	  /* We have not sent the appropriate event yet, so the
           * client must not have issued a write:maxLength:
	   * (which is the point at which we should send).
	   */
	  return YES;
	}
    }
  return NO;
}

@end
@implementation	GSAbstractServerStream
+ (void) initialize
{
  if (self == [GSAbstractServerStream class])
    {
      GSObjCAddClassBehavior(self, [GSStream class]);
    }
}
@end


@implementation GSDataInputStream

/**
 * the designated initializer
 */ 
- (id) initWithData: (NSData *)data
{
  if ((self = [super init]) != nil)
    {
      ASSIGN(_data, data);
      _pointer = 0;
    }
  return self;
}

- (void) dealloc
{
  if ([self _isOpened])
    [self close];
  RELEASE(_data);
  [super dealloc];
}

- (int) read: (uint8_t *)buffer maxLength: (unsigned int)len
{
  unsigned long dataSize;
  unsigned long copySize;

  if (buffer == 0)
    {
      [NSException raise: NSInvalidArgumentException
		  format: @"null pointer for buffer"];
    }
  if (len == 0)
    {
      [NSException raise: NSInvalidArgumentException
		  format: @"zero byte read write requested"];
    }

  _events &= ~NSStreamEventHasSpaceAvailable;

  if ([self streamStatus] == NSStreamStatusClosed)
    {
      return 0;
    }

  dataSize = [_data length];
  NSAssert(dataSize >= _pointer, @"Buffer overflow!");
  if (len + _pointer > dataSize)
    {
      copySize = dataSize - _pointer;
    }
  else
    {
      copySize = len;
    }
  if (copySize) 
    {
      memcpy(buffer, [_data bytes] + _pointer, copySize);
      _pointer = _pointer + copySize;
    }
  else
    {
      [self _setStatus: NSStreamStatusAtEnd];
      [self _sendEvent: NSStreamEventEndEncountered];
    }
  return copySize;
}

- (BOOL) getBuffer: (uint8_t **)buffer length: (unsigned int *)len
{
  unsigned long dataSize = [_data length];

  NSAssert(dataSize >= _pointer, @"Buffer overflow!");
  *buffer = (uint8_t*)[_data bytes] + _pointer;
  *len = dataSize - _pointer;
  return YES;
}

- (BOOL) hasBytesAvailable
{
  unsigned long dataSize = [_data length];

  return (dataSize > _pointer);
}

- (id) propertyForKey: (NSString *)key
{
  if ([key isEqualToString: NSStreamFileCurrentOffsetKey])
    return [NSNumber numberWithLong: _pointer];
  return [super propertyForKey: key];
}

- (void) _dispatch
{
  BOOL av = [self hasBytesAvailable];
  NSStreamEvent myEvent = av ? NSStreamEventHasBytesAvailable : 
    NSStreamEventEndEncountered;
  NSStreamStatus myStatus = av ? NSStreamStatusOpen : NSStreamStatusAtEnd;
  
  [self _setStatus: myStatus];
  [self _sendEvent: myEvent];
}

@end


@implementation GSBufferOutputStream

- (id) initToBuffer: (uint8_t *)buffer capacity: (unsigned int)capacity
{
  if ((self = [super init]) != nil)
    {
      _buffer = buffer;
      _capacity = capacity;
      _pointer = 0;
    }
  return self;
}

- (int) write: (const uint8_t *)buffer maxLength: (unsigned int)len
{
  if (buffer == 0)
    {
      [NSException raise: NSInvalidArgumentException
		  format: @"null pointer for buffer"];
    }
  if (len == 0)
    {
      [NSException raise: NSInvalidArgumentException
		  format: @"zero byte length write requested"];
    }

  _events &= ~NSStreamEventHasBytesAvailable;

  if ([self streamStatus] == NSStreamStatusClosed)
    {
      return 0;
    }

  if ((_pointer + len) > _capacity)
    {
      len = _capacity - _pointer;
      if (len == 0)
	{
	  [self _setStatus: NSStreamStatusAtEnd];
	  [self _sendEvent: NSStreamEventEndEncountered];
	  return 0;
	}
    }
  memcpy((_buffer + _pointer), buffer, len);
  _pointer += len;
  return len;
}

- (id) propertyForKey: (NSString *)key
{
  if ([key isEqualToString: NSStreamFileCurrentOffsetKey])
    {
      return [NSNumber numberWithLong: _pointer];
    }
  return [super propertyForKey: key];
}

- (void) _dispatch
{
  BOOL av = [self hasSpaceAvailable];
  NSStreamEvent myEvent = av ? NSStreamEventHasSpaceAvailable : 
    NSStreamEventEndEncountered;

  [self _sendEvent: myEvent];
}

@end

@implementation GSDataOutputStream

- (id) init
{
  if ((self = [super init]) != nil)
    {
      _data = [NSMutableData new];
      _pointer = 0;
    }
  return self;
}

- (void) dealloc
{
  RELEASE(_data);
  [super dealloc];
}

- (int) write: (const uint8_t *)buffer maxLength: (unsigned int)len
{
  if (buffer == 0)
    {
      [NSException raise: NSInvalidArgumentException
		  format: @"null pointer for buffer"];
    }
  if (len == 0)
    {
      [NSException raise: NSInvalidArgumentException
		  format: @"zero byte length write requested"];
    }

  _events &= ~NSStreamEventHasBytesAvailable;

  if ([self streamStatus] == NSStreamStatusClosed)
    {
      return 0;
    }

  [_data appendBytes: buffer length: len];
  _pointer += len;
  return len;
}

- (BOOL) hasSpaceAvailable
{
  return YES;
}

- (id) propertyForKey: (NSString *)key
{
  if ([key isEqualToString: NSStreamFileCurrentOffsetKey])
    {
      return [NSNumber numberWithLong: _pointer];
    }
  else if ([key isEqualToString: NSStreamDataWrittenToMemoryStreamKey])
    {
      return _data;
    }
  return [super propertyForKey: key];
}

- (void) _dispatch
{
  BOOL av = [self hasSpaceAvailable];
  NSStreamEvent myEvent = av ? NSStreamEventHasSpaceAvailable : 
    NSStreamEventEndEncountered;

  [self _sendEvent: myEvent];
}

@end


/*
 * States for socks connection negotiation
 */
static NSString * const GSSOCKSOfferAuth = @"GSSOCKSOfferAuth";
static NSString * const GSSOCKSRecvAuth = @"GSSOCKSRecvAuth";
static NSString * const GSSOCKSSendAuth = @"GSSOCKSSendAuth";
static NSString * const GSSOCKSAckAuth = @"GSSOCKSAckAuth";
static NSString * const GSSOCKSSendConn = @"GSSOCKSSendConn";
static NSString * const GSSOCKSAckConn = @"GSSOCKSAckConn";

@interface	GSSOCKS
{
  NSString		*state;
  NSString		*addr;
  int			port;
  int			roffset;
  int			woffset;
  int			rwant;
  unsigned char		rbuffer[128];
  NSInputStream		*istream;
  NSOutputStream	*ostream;
}
- (NSString*) addr;
- (id) initToAddr: (NSString*)_addr port: (int)_port;
- (int) port;
- (NSString*) stream: (NSStream*)stream SOCKSEvent: (NSStreamEvent)event;
@end

@implementation	GSSOCKS
- (NSString*) addr
{
  return addr;
}

- (id) initToAddr: (NSString*)_addr port: (int)_port
{
  ASSIGNCOPY(addr, _addr);
  port = _port;
  state = GSSOCKSOfferAuth;
  return self;
}

- (int) port
{
  return port;
}

- (NSString*) stream: (NSStream*)stream SOCKSEvent: (NSStreamEvent)event
{
  NSString		*error = nil;
  NSDictionary		*conf;
  NSString		*user;
  NSString		*pass;

  if (event == NSStreamEventErrorOccurred
    || [stream streamStatus] == NSStreamStatusError
    || [stream streamStatus] == NSStreamStatusClosed)
    {
      return @"SOCKS errur during negotiation";
    }

  conf = [stream propertyForKey: NSStreamSOCKSProxyConfigurationKey];
  user = [conf objectForKey: NSStreamSOCKSProxyUserKey];
  pass = [conf objectForKey: NSStreamSOCKSProxyPasswordKey];
  if ([[conf objectForKey: NSStreamSOCKSProxyVersionKey]
    isEqual: NSStreamSOCKSProxyVersion4] == YES)
    {
    }
  else
    {
      again:

      if (state == GSSOCKSOfferAuth)
	{
	  int		result;
	  int		want;
	  unsigned char	buf[4];

	  /*
	   * Authorisation record is at least three bytes -
	   *   socks version (5)
	   *   authorisation method bytes to follow (1)
	   *   say we do no authorisation (0)
	   *   say we do user/pass authorisation (2)
	   */
	  buf[0] = 5;
	  if (user && pass)
	    {
	      buf[1] = 2;
	      buf[2] = 2;
	      buf[3] = 0;
	      want = 4;
	    }
	  else
	    {
	      buf[1] = 1;
	      buf[2] = 0;
	      want = 3;
	    }

	  result = [ostream write: buf + woffset maxLength: 4 - woffset];
	  if (result == 0)
	    {
	      error = @"end-of-file during SOCKS negotiation";
	    }
	  else if (result > 0)
	    {
	      woffset += result;
	      if (woffset == want)
		{
		  woffset = 0;
		  state = GSSOCKSRecvAuth;
		  goto again;
		}
	    }
	}
      else if (state == GSSOCKSRecvAuth)
	{
	  int	result;

	  result = [istream read: rbuffer + roffset maxLength: 2 - roffset];
	  if (result == 0)
	    {
	      error = @"SOCKS end-of-file during negotiation";
	    }
	  else if (result > 0)
	    {
	      roffset += result;
	      if (roffset == 2)
		{
		  roffset = 0;
		  if (rbuffer[0] != 5)
		    {
		      error = @"SOCKS authorisation response had wrong version";
		    }
		  else if (rbuffer[1] == 0)
		    {
		      state = GSSOCKSSendConn;
		      goto again;
		    }
		  else if (rbuffer[1] == 2)
		    {
		      state = GSSOCKSSendAuth;
		      goto again;
		    }
		  else
		    {
		      error = @"SOCKS authorisation response had wrong method";
		    }
		}
	    }
	}
      else if (state == GSSOCKSSendAuth)
	{
	  NSData	*u = [user dataUsingEncoding: NSUTF8StringEncoding];
	  unsigned	ul = [u length];
	  NSData	*p = [pass dataUsingEncoding: NSUTF8StringEncoding];
	  unsigned	pl = [p length];

	  if (ul < 1 || ul > 255)
	    {
	      error = @"NSStreamSOCKSProxyUserKey value too long";
	    }
	  else if (ul < 1 || ul > 255)
	    {
	      error = @"NSStreamSOCKSProxyPasswordKey value too long";
	    }
	  else
	    {
	      int		want = ul + pl + 3;
	      unsigned char	buf[want];
	      int		result;

	      buf[0] = 5;
	      buf[1] = ul;
	      memcpy(buf + 2, [u bytes], ul);
	      buf[ul + 2] = pl;
	      memcpy(buf + ul + 3, [p bytes], pl);
	      result = [ostream write: buf + woffset maxLength: want - woffset];
	      if (result == 0)
		{
		  error = @"SOCKS end-of-file during negotiation";
		}
	      else if (result > 0)
		{
		  woffset += result;
		  if (woffset == want)
		    {
		      state = GSSOCKSAckAuth;
		      goto again;
		    }
		}
	    }
	}
      else if (state == GSSOCKSAckAuth)
	{
	  int	result;

	  result = [istream read: rbuffer + roffset maxLength: 2 - roffset];
	  if (result == 0)
	    {
	      error = @"SOCKS end-of-file during negotiation";
	    }
	  else if (result > 0)
	    {
	      roffset += result;
	      if (roffset == 2)
		{
		  roffset = 0;
		  if (rbuffer[0] != 5)
		    {
		      error = @"SOCKS authorisation response had wrong version";
		    }
		  else if (rbuffer[1] == 0)
		    {
		      state = GSSOCKSSendConn;
		      goto again;
		    }
		  else if (rbuffer[1] == 2)
		    {
		      error = @"SOCKS authorisation failed";
		    }
		}
	    }
	}
      else if (state == GSSOCKSSendConn)
	{
	  unsigned char	buf[10];
	  int		want = 10;
	  int		result;
	  const char	*ptr;

	  /*
	   * Connect command is ten bytes -
	   *   socks version
	   *   connect command
	   *   reserved byte
	   *   address type
	   *   address 4 bytes (big endian)
	   *   port 2 bytes (big endian)
	   */
	  buf[0] = 5;	// Socks version number
	  buf[1] = 1;	// Connect command
	  buf[2] = 0;	// Reserved
	  buf[3] = 1;	// Address type (IPV4)
	  ptr = [addr lossyCString];
	  buf[4] = atoi(ptr);
	  while (isdigit(*ptr))
	    ptr++;
	  ptr++;
	  buf[5] = atoi(ptr);
	  while (isdigit(*ptr))
	    ptr++;
	  ptr++;
	  buf[6] = atoi(ptr);
	  while (isdigit(*ptr))
	    ptr++;
	  ptr++;
	  buf[7] = atoi(ptr);
	  buf[8] = ((port & 0xff00) >> 8);
	  buf[9] = (port & 0xff);

	  result = [ostream write: buf + woffset maxLength: want - woffset];
	  if (result == 0)
	    {
	      error = @"SOCKS end-of-file during negotiation";
	    }
	  else if (result > 0)
	    {
	      woffset += result;
	      if (woffset == want)
		{
		  rwant = 5;
		  state = GSSOCKSAckConn;
		  goto again;
		}
	    }
	}
      else if (state == GSSOCKSAckConn)
	{
	  int	result;

	  result = [istream read: rbuffer + roffset maxLength: rwant - roffset];
	  if (result == 0)
	    {
	      error = @"SOCKS end-of-file during negotiation";
	    }
	  else if (result > 0)
	    {
	      roffset += result;
	      if (roffset == rwant)
		{
		  if (rbuffer[0] != 5)
		    {
		      error = @"connect response from SOCKS had wrong version";
		    }
		  else if (rbuffer[1] != 0)
		    {
		      switch (rbuffer[1])
			{
			  case 1:
			    error = @"SOCKS server general failure";
			    break;
			  case 2:
			    error = @"SOCKS server says permission denied";
			    break;
			  case 3:
			    error = @"SOCKS server says network unreachable";
			    break;
			  case 4:
			    error = @"SOCKS server says host unreachable";
			    break;
			  case 5:
			    error = @"SOCKS server says connection refused";
			    break;
			  case 6:
			    error = @"SOCKS server says connection timed out";
			    break;
			  case 7:
			    error = @"SOCKS server says command not supported";
			    break;
			  case 8:
			    error = @"SOCKS server says address not supported";
			    break;
			  default:
			    error = @"connect response from SOCKS was failure";
			    break;
			}
		    }
		  else if (rbuffer[3] == 1)
		    {
		      rwant = 10;		// Fixed size (IPV4) address
		    }
		  else if (rbuffer[3] == 3)
		    {
		      rwant = 7 + rbuffer[4];	// Domain name leading length
		    }
		  else if (rbuffer[3] == 4)
		    {
		      rwant = 22;		// Fixed size (IPV6) address
		    }
		  else
		    {
		      error = @"SOCKS server returned unknown address type";
		    }
		  if (error == nil)
		    {
		      if (roffset < rwant)
			{
			  goto again;	// Need address/port bytes
			}
		      else
			{
			  NSString	*a;

			  error = @"";	// success
			  if (rbuffer[3] == 1)
			    {
			      a = [NSString stringWithFormat: @"%d.%d.%d.%d",
			        rbuffer[4], rbuffer[5], rbuffer[6], rbuffer[7]];
			    }
			  else if (rbuffer[3] == 3)
			    {
			      rbuffer[rwant] = '\0';
			      a = [NSString stringWithUTF8String:
			        (const char*)rbuffer];
			    }
			  else
			    {
			      unsigned char	buf[40];
			      int		i = 4;
			      int		j = 0;

			      while (i < rwant)
			        {
				  int	val = rbuffer[i++] * 256 + rbuffer[i++];

				  if (i > 4)
				    {
				      buf[j++] = ':';
				    }
				  sprintf((char*)&buf[j], "%04x", val);
				  j += 4;
				}
			      a = [NSString stringWithUTF8String:
			        (const char*)buf];
			    }
			  ASSIGN(addr, a);
			  port =  rbuffer[rwant-1] * 256 * rbuffer[rwant-2];
			}
		    }
		}
	    }
	}
    }

  return error;
}

@end