java/common/JNISupport.c

/* -*- Mode: C; tab-width: 4 -*-
 *
 * Copyright (c) 2004 Apple Computer, Inc. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.

    Change History (most recent first):

$Log: JNISupport.c,v $
Revision 1.17  2006/08/14 23:25:08  cheshire
Re-licensed mDNSResponder daemon source code under Apache License, Version 2.0

Revision 1.16  2006/07/14 02:35:47  cheshire
Added (commented out) syslog debugging messages

Revision 1.15  2006/06/27 19:34:43  cheshire
<rdar://problem/4430023> txtRecord parameter of DNSServiceResolveReply() should be unsigned char *

Revision 1.14  2006/06/20 23:03:35  rpantos
<rdar://problem/3839132> Java needs to implement DNSServiceRegisterRecord equivalent

Revision 1.13  2005/10/26 01:52:24  cheshire
<rdar://problem/4316286> Race condition in Java code (doesn't work at all on Linux)

Revision 1.12  2005/07/13 19:20:32  cheshire
<rdar://problem/4175511> Race condition in Java API
Additional cleanup suggested by Roger -- NewContext() doesn't need ownerClass parameter any more

Revision 1.11  2005/07/11 01:55:21  cheshire
<rdar://problem/4175511> Race condition in Java API

Revision 1.10  2005/07/05 13:01:52  cheshire
<rdar://problem/4169791> If mDNSResponder daemon is stopped, Java API spins, burning CPU time

Revision 1.9  2004/12/11 03:01:00  rpantos
<rdar://problem/3907498> Java DNSRecord API should be cleaned up

Revision 1.8  2004/11/30 23:51:05  cheshire
Remove double semicolons

Revision 1.7  2004/11/23 08:12:04  shersche
Implement if_nametoindex and if_indextoname for Win32 platforms

Revision 1.6  2004/11/23 03:41:14  cheshire
Change JNISupport.c to call if_indextoname & if_nametoindex directly.
(May require some additional glue code to work on Windows.)

Revision 1.5  2004/11/17 17:07:44  cheshire
Updated comment about AUTO_CALLBACKS

Revision 1.4  2004/11/12 03:23:09  rpantos
rdar://problem/3809541 implement getIfIndexForName, getNameForIfIndex.

Revision 1.3  2004/06/18 04:44:17  rpantos
Adapt to API unification on Windows

Revision 1.2  2004/05/28 23:34:42  ksekar
<rdar://problem/3672903>: Java project build errors

Revision 1.1  2004/04/30 16:29:35  rpantos
First checked in.


	This file contains the platform support for DNSSD and related Java classes.
	It is used to shim through to the underlying <dns_sd.h> API.
 */

#pragma ident	"%Z%%M%	%I%	%E% SMI"

// AUTO_CALLBACKS should be set to 1 if the underlying mDNS implementation fires response
// callbacks automatically (as in the early Windows prototypes).
// AUTO_CALLBACKS should be set to 0 if the client must call DNSServiceProcessResult() to
// invoke response callbacks (as is true on Mac OS X, Posix, Windows, etc.).
// (Invoking callbacks automatically on a different thread sounds attractive, but while
// the client gains by not needing to add an event source to its main event loop, it loses
// by being forced to deal with concurrency and locking, which can be a bigger burden.)
#ifndef	AUTO_CALLBACKS
#define	AUTO_CALLBACKS	0
#endif

#if !AUTO_CALLBACKS
#ifdef _WIN32
#include <winsock2.h>
#else //_WIN32
#include <sys/types.h>
#include <sys/select.h>
#endif // _WIN32
#endif // AUTO_CALLBACKS

#include <dns_sd.h>

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#ifdef _WIN32
#include <winsock2.h>
#include <iphlpapi.h>
static char	*	if_indextoname( DWORD ifIndex, char * nameBuff);
static DWORD	if_nametoindex( const char * nameStr );
#define IF_NAMESIZE MAX_ADAPTER_NAME_LENGTH
#else // _WIN32
#include <sys/socket.h>
#include <net/if.h>
#endif // _WIN32
#include <jni.h>

#include "DNSSD.java.h"

//#include <syslog.h>

// convenience definition
#ifdef __GNUC__
#define	_UNUSED	__attribute__ ((unused))
#else
#define	_UNUSED
#endif

enum {
	kInterfaceVersion = 1		// Must match version in .jar file
};

typedef struct OpContext	OpContext;

struct	OpContext
{
	DNSServiceRef	ServiceRef;
	JNIEnv			*Env;
	jobject			JavaObj;
	jobject			ClientObj;
	jmethodID		Callback;
	jmethodID		Callback2;
};

// For AUTO_CALLBACKS, we must attach the callback thread to the Java VM prior to upcall.
#if AUTO_CALLBACKS
JavaVM		*gJavaVM = NULL;
#endif


JNIEXPORT jint JNICALL Java_com_apple_dnssd_AppleDNSSD_InitLibrary( JNIEnv *pEnv, jclass cls,
						jint callerVersion)
{
	/* Ensure that caller & interface versions match. */
	if ( callerVersion != kInterfaceVersion)
		return kDNSServiceErr_Incompatible;

#if AUTO_CALLBACKS
	{
		jsize	numVMs;

		if ( 0 != JNI_GetCreatedJavaVMs( &gJavaVM, 1, &numVMs))
			return kDNSServiceErr_BadState;
	}
#endif

	// Set AppleDNSSD.hasAutoCallbacks
	{
#if AUTO_CALLBACKS
		jboolean	hasAutoC = JNI_TRUE;
#else
		jboolean	hasAutoC = JNI_FALSE;
#endif
		jfieldID	hasAutoCField = (*pEnv)->GetStaticFieldID( pEnv, cls, "hasAutoCallbacks", "Z");
		(*pEnv)->SetStaticBooleanField( pEnv, cls, hasAutoCField, hasAutoC);
	}

	return kDNSServiceErr_NoError;
}


static const char*	SafeGetUTFChars( JNIEnv *pEnv, jstring str)
// Wrapper for JNI GetStringUTFChars() that returns NULL for null str.
{
	return str != NULL ? (*pEnv)->GetStringUTFChars( pEnv, str, 0) : NULL;
}

static void			SafeReleaseUTFChars( JNIEnv *pEnv, jstring str, const char *buff)
// Wrapper for JNI GetStringUTFChars() that handles null str.
{
	if ( str != NULL)
		(*pEnv)->ReleaseStringUTFChars( pEnv, str, buff);
}


#if AUTO_CALLBACKS
static void	SetupCallbackState( JNIEnv **ppEnv)
{
	(*gJavaVM)->AttachCurrentThread( gJavaVM, (void**) ppEnv, NULL);
}

static void	TeardownCallbackState( void )
{
	(*gJavaVM)->DetachCurrentThread( gJavaVM);
}

#else	// AUTO_CALLBACKS

static void	SetupCallbackState( JNIEnv **ppEnv _UNUSED)
{
	// No setup necessary if ProcessResults() has been called
}

static void	TeardownCallbackState( void )
{
	// No teardown necessary if ProcessResults() has been called
}
#endif	// AUTO_CALLBACKS


static OpContext	*NewContext( JNIEnv *pEnv, jobject owner,
								const char *callbackName, const char *callbackSig)
// Create and initialize a new OpContext.
{
	OpContext				*pContext = (OpContext*) malloc( sizeof *pContext);

	if ( pContext != NULL)
	{
		jfieldID		clientField = (*pEnv)->GetFieldID( pEnv, (*pEnv)->GetObjectClass( pEnv, owner),
															"fListener", "Lcom/apple/dnssd/BaseListener;");

		pContext->JavaObj = (*pEnv)->NewWeakGlobalRef( pEnv, owner);	// must convert local ref to global to cache;
		pContext->ClientObj = (*pEnv)->GetObjectField( pEnv, owner, clientField);
		pContext->ClientObj = (*pEnv)->NewWeakGlobalRef( pEnv, pContext->ClientObj);	// must convert local ref to global to cache
		pContext->Callback = (*pEnv)->GetMethodID( pEnv,
								(*pEnv)->GetObjectClass( pEnv, pContext->ClientObj),
								callbackName, callbackSig);
		pContext->Callback2 = NULL;		// not always used
	}

	return pContext;
}


static void			ReportError( JNIEnv *pEnv, jobject target, jobject service, DNSServiceErrorType err)
// Invoke operationFailed() method on target with err.
{
	jclass			cls = (*pEnv)->GetObjectClass( pEnv, target);
	jmethodID		opFailed = (*pEnv)->GetMethodID( pEnv, cls, "operationFailed",
								"(Lcom/apple/dnssd/DNSSDService;I)V");

	(*pEnv)->CallVoidMethod( pEnv, target, opFailed, service, err);
}

JNIEXPORT void JNICALL Java_com_apple_dnssd_AppleService_HaltOperation( JNIEnv *pEnv, jobject pThis)
/* Deallocate the dns_sd service browser and set the Java object's fNativeContext field to 0. */
{
	jclass			cls = (*pEnv)->GetObjectClass( pEnv, pThis);
	jfieldID		contextField = (*pEnv)->GetFieldID( pEnv, cls, "fNativeContext", "J");

	if ( contextField != 0)
	{
		OpContext	*pContext = (OpContext*) (*pEnv)->GetLongField( pEnv, pThis, contextField);
		if ( pContext != NULL)
		{
			// MUST clear fNativeContext first, BEFORE calling DNSServiceRefDeallocate()
			(*pEnv)->SetLongField( pEnv, pThis, contextField, 0);
			if ( pContext->ServiceRef != NULL)
				DNSServiceRefDeallocate( pContext->ServiceRef);

			(*pEnv)->DeleteWeakGlobalRef( pEnv, pContext->JavaObj);
			(*pEnv)->DeleteWeakGlobalRef( pEnv, pContext->ClientObj);
			free( pContext);
		}
	}
}


JNIEXPORT jint JNICALL Java_com_apple_dnssd_AppleService_BlockForData( JNIEnv *pEnv, jobject pThis)
/* Block until data arrives, or one second passes. Returns 1 if data present, 0 otherwise. */
{
// BlockForData() not supported with AUTO_CALLBACKS
#if !AUTO_CALLBACKS
	jclass			cls = (*pEnv)->GetObjectClass( pEnv, pThis);
	jfieldID		contextField = (*pEnv)->GetFieldID( pEnv, cls, "fNativeContext", "J");

	if ( contextField != 0)
	{
		OpContext	*pContext = (OpContext*) (*pEnv)->GetLongField( pEnv, pThis, contextField);
		if ( pContext != NULL)
		{
			fd_set			readFDs;
			int				sd = DNSServiceRefSockFD( pContext->ServiceRef);
			struct timeval	timeout = { 1, 0 };
			FD_ZERO( &readFDs);
			FD_SET( sd, &readFDs);

			// Q: Why do we poll here?
			// A: Because there's no other thread-safe way to do it.
			// Mac OS X terminates a select() call if you close one of the sockets it's listening on, but Linux does not,
			// and arguably Linux is correct (See <http://www.ussg.iu.edu/hypermail/linux/kernel/0405.1/0418.html>)
			// The problem is that the Mac OS X behaviour assumes that it's okay for one thread to close a socket while
			// some other thread is monitoring that socket in select(), but the difficulty is that there's no general way
			// to make that thread-safe, because there's no atomic way to enter select() and release a lock simultaneously.
			// If we try to do this without holding any lock, then right as we jump to the select() routine,
			// some other thread could stop our operation (thereby closing the socket),
			// and then that thread (or even some third, unrelated thread)
			// could do some other DNS-SD operation (or some other operation that opens a new file descriptor)
			// and then we'd blindly resume our fall into the select() call, now blocking on a file descriptor
			// that may coincidentally have the same numerical value, but is semantically unrelated
			// to the true file descriptor we thought we were blocking on.
			// We can't stop this race condition from happening, but at least if we wake up once a second we can detect
			// when fNativeContext has gone to zero, and thereby discover that we were blocking on the wrong fd.

			if (select( sd + 1, &readFDs, (fd_set*) NULL, (fd_set*) NULL, &timeout) == 1) return(1);
		}
	}
#endif // !AUTO_CALLBACKS
	return(0);
}


JNIEXPORT jint JNICALL Java_com_apple_dnssd_AppleService_ProcessResults( JNIEnv *pEnv, jobject pThis)
/* Call through to DNSServiceProcessResult() while data remains on socket. */
{
#if !AUTO_CALLBACKS	// ProcessResults() not supported with AUTO_CALLBACKS

	jclass			cls = (*pEnv)->GetObjectClass( pEnv, pThis);
	jfieldID		contextField = (*pEnv)->GetFieldID( pEnv, cls, "fNativeContext", "J");
	OpContext		*pContext = (OpContext*) (*pEnv)->GetLongField( pEnv, pThis, contextField);
	DNSServiceErrorType err = kDNSServiceErr_BadState;

	if ( pContext != NULL)
	{
		int				sd = DNSServiceRefSockFD( pContext->ServiceRef);
		fd_set			readFDs;
		struct timeval	zeroTimeout = { 0, 0 };

		pContext->Env = pEnv;

		FD_ZERO( &readFDs);
		FD_SET( sd, &readFDs);

		err = kDNSServiceErr_NoError;
		if (0 < select(sd + 1, &readFDs, (fd_set*) NULL, (fd_set*) NULL, &zeroTimeout))
		{
			err = DNSServiceProcessResult(pContext->ServiceRef);
			// Use caution here!
			// We cannot touch any data structures associated with this operation!
			// The DNSServiceProcessResult() routine should have invoked our callback,
			// and our callback could have terminated the operation with op.stop();
			// and that means HaltOperation() will have been called, which frees pContext.
			// Basically, from here we just have to get out without touching any stale
			// data structures that could blow up on us! Particularly, any attempt
			// to loop here reading more results from the file descriptor is unsafe.
		}
	}
	return err;
#endif // AUTO_CALLBACKS
}


static void DNSSD_API	ServiceBrowseReply( DNSServiceRef sdRef _UNUSED, DNSServiceFlags flags, uint32_t interfaceIndex,
								DNSServiceErrorType errorCode, const char *serviceName, const char *regtype,
								const char *replyDomain, void *context)
{
	OpContext		*pContext = (OpContext*) context;

	SetupCallbackState( &pContext->Env);

	if ( pContext->ClientObj != NULL && pContext->Callback != NULL)
	{
		if ( errorCode == kDNSServiceErr_NoError)
		{
			(*pContext->Env)->CallVoidMethod( pContext->Env, pContext->ClientObj,
								( flags & kDNSServiceFlagsAdd) != 0 ? pContext->Callback : pContext->Callback2,
								pContext->JavaObj, flags, interfaceIndex,
								(*pContext->Env)->NewStringUTF( pContext->Env, serviceName),
								(*pContext->Env)->NewStringUTF( pContext->Env, regtype),
								(*pContext->Env)->NewStringUTF( pContext->Env, replyDomain));
		}
		else
			ReportError( pContext->Env, pContext->ClientObj, pContext->JavaObj, errorCode);
	}

	TeardownCallbackState();
}

JNIEXPORT jint JNICALL Java_com_apple_dnssd_AppleBrowser_CreateBrowser( JNIEnv *pEnv, jobject pThis,
							jint flags, jint ifIndex, jstring regType, jstring domain)
{
	jclass					cls = (*pEnv)->GetObjectClass( pEnv, pThis);
	jfieldID				contextField = (*pEnv)->GetFieldID( pEnv, cls, "fNativeContext", "J");
	OpContext				*pContext = NULL;
	DNSServiceErrorType		err = kDNSServiceErr_NoError;

	if ( contextField != 0)
		pContext = NewContext( pEnv, pThis, "serviceFound",
								"(Lcom/apple/dnssd/DNSSDService;IILjava/lang/String;Ljava/lang/String;Ljava/lang/String;)V");
	else
		err = kDNSServiceErr_BadParam;

	if ( pContext != NULL)
	{
		const char	*regStr = SafeGetUTFChars( pEnv, regType);
		const char	*domainStr = SafeGetUTFChars( pEnv, domain);

		pContext->Callback2 = (*pEnv)->GetMethodID( pEnv,
								(*pEnv)->GetObjectClass( pEnv, pContext->ClientObj),
								"serviceLost", "(Lcom/apple/dnssd/DNSSDService;IILjava/lang/String;Ljava/lang/String;Ljava/lang/String;)V");

		err = DNSServiceBrowse( &pContext->ServiceRef, flags, ifIndex, regStr, domainStr, ServiceBrowseReply, pContext);
		if ( err == kDNSServiceErr_NoError)
		{
			(*pEnv)->SetLongField( pEnv, pThis, contextField, (jlong) pContext);
		}

		SafeReleaseUTFChars( pEnv, regType, regStr);
		SafeReleaseUTFChars( pEnv, domain, domainStr);
	}
	else
		err = kDNSServiceErr_NoMemory;

	return err;
}


static void DNSSD_API	ServiceResolveReply( DNSServiceRef sdRef _UNUSED, DNSServiceFlags flags, uint32_t interfaceIndex,
								DNSServiceErrorType errorCode, const char *fullname, const char *hosttarget,
								uint16_t port, uint16_t txtLen, const unsigned char *txtRecord, void *context)
{
	OpContext		*pContext = (OpContext*) context;
	jclass			txtCls;
	jmethodID		txtCtor;
	jbyteArray		txtBytes;
	jobject			txtObj;
	jbyte			*pBytes;

	SetupCallbackState( &pContext->Env);

	txtCls = (*pContext->Env)->FindClass( pContext->Env, "com/apple/dnssd/TXTRecord");
	txtCtor = (*pContext->Env)->GetMethodID( pContext->Env, txtCls, "<init>", "([B)V");

	if ( pContext->ClientObj != NULL && pContext->Callback != NULL && txtCtor != NULL &&
		 NULL != ( txtBytes = (*pContext->Env)->NewByteArray( pContext->Env, txtLen)))
	{
		if ( errorCode == kDNSServiceErr_NoError)
		{
			// Since Java ints are defined to be big-endian, we canonicalize 'port' from a 16-bit
			// pattern into a number here.
			port = ( ((unsigned char*) &port)[0] << 8) | ((unsigned char*) &port)[1];

			// Initialize txtBytes with contents of txtRecord
			pBytes = (*pContext->Env)->GetByteArrayElements( pContext->Env, txtBytes, NULL);
			memcpy( pBytes, txtRecord, txtLen);
			(*pContext->Env)->ReleaseByteArrayElements( pContext->Env, txtBytes, pBytes, JNI_COMMIT);

			// Construct txtObj with txtBytes
			txtObj = (*pContext->Env)->NewObject( pContext->Env, txtCls, txtCtor, txtBytes);
			(*pContext->Env)->DeleteLocalRef( pContext->Env, txtBytes);

			(*pContext->Env)->CallVoidMethod( pContext->Env, pContext->ClientObj, pContext->Callback,
								pContext->JavaObj, flags, interfaceIndex,
								(*pContext->Env)->NewStringUTF( pContext->Env, fullname),
								(*pContext->Env)->NewStringUTF( pContext->Env, hosttarget),
								port, txtObj);
		}
		else
			ReportError( pContext->Env, pContext->ClientObj, pContext->JavaObj, errorCode);
	}

	TeardownCallbackState();
}

JNIEXPORT jint JNICALL Java_com_apple_dnssd_AppleResolver_CreateResolver( JNIEnv *pEnv, jobject pThis,
							jint flags, jint ifIndex, jstring serviceName, jstring regType, jstring domain)
{
	jclass					cls = (*pEnv)->GetObjectClass( pEnv, pThis);
	jfieldID				contextField = (*pEnv)->GetFieldID( pEnv, cls, "fNativeContext", "J");
	OpContext				*pContext = NULL;
	DNSServiceErrorType		err = kDNSServiceErr_NoError;

	if ( contextField != 0)
		pContext = NewContext( pEnv, pThis, "serviceResolved",
								"(Lcom/apple/dnssd/DNSSDService;IILjava/lang/String;Ljava/lang/String;ILcom/apple/dnssd/TXTRecord;)V");
	else
		err = kDNSServiceErr_BadParam;

	if ( pContext != NULL)
	{
		const char	*servStr = SafeGetUTFChars( pEnv, serviceName);
		const char	*regStr = SafeGetUTFChars( pEnv, regType);
		const char	*domainStr = SafeGetUTFChars( pEnv, domain);

		err = DNSServiceResolve( &pContext->ServiceRef, flags, ifIndex,
								servStr, regStr, domainStr, ServiceResolveReply, pContext);
		if ( err == kDNSServiceErr_NoError)
		{
			(*pEnv)->SetLongField( pEnv, pThis, contextField, (jlong) pContext);
		}

		SafeReleaseUTFChars( pEnv, serviceName, servStr);
		SafeReleaseUTFChars( pEnv, regType, regStr);
		SafeReleaseUTFChars( pEnv, domain, domainStr);
	}
	else
		err = kDNSServiceErr_NoMemory;

	return err;
}


static void DNSSD_API	ServiceRegisterReply( DNSServiceRef sdRef _UNUSED, DNSServiceFlags flags,
								DNSServiceErrorType errorCode, const char *serviceName,
								const char *regType, const char *domain, void *context)
{
	OpContext		*pContext = (OpContext*) context;

	SetupCallbackState( &pContext->Env);

	if ( pContext->ClientObj != NULL && pContext->Callback != NULL)
	{
		if ( errorCode == kDNSServiceErr_NoError)
		{
			(*pContext->Env)->CallVoidMethod( pContext->Env, pContext->ClientObj, pContext->Callback,
								pContext->JavaObj, flags,
								(*pContext->Env)->NewStringUTF( pContext->Env, serviceName),
								(*pContext->Env)->NewStringUTF( pContext->Env, regType),
								(*pContext->Env)->NewStringUTF( pContext->Env, domain));
		}
		else
			ReportError( pContext->Env, pContext->ClientObj, pContext->JavaObj, errorCode);
	}
	TeardownCallbackState();
}

JNIEXPORT jint JNICALL Java_com_apple_dnssd_AppleRegistration_BeginRegister( JNIEnv *pEnv, jobject pThis,
							jint ifIndex, jint flags, jstring serviceName, jstring regType,
							jstring domain, jstring host, jint port, jbyteArray txtRecord)
{
	//syslog(LOG_ERR, "BR");
	jclass					cls = (*pEnv)->GetObjectClass( pEnv, pThis);
	jfieldID				contextField = (*pEnv)->GetFieldID( pEnv, cls, "fNativeContext", "J");
	OpContext				*pContext = NULL;
	DNSServiceErrorType		err = kDNSServiceErr_NoError;
	jbyte					*pBytes;
	jsize					numBytes;

	//syslog(LOG_ERR, "BR: contextField %d", contextField);

	if ( contextField != 0)
		pContext = NewContext( pEnv, pThis, "serviceRegistered",
								"(Lcom/apple/dnssd/DNSSDRegistration;ILjava/lang/String;Ljava/lang/String;Ljava/lang/String;)V");
	else
		err = kDNSServiceErr_BadParam;

	if ( pContext != NULL)
	{
		const char	*servStr = SafeGetUTFChars( pEnv, serviceName);
		const char	*regStr = SafeGetUTFChars( pEnv, regType);
		const char	*domainStr = SafeGetUTFChars( pEnv, domain);
		const char	*hostStr = SafeGetUTFChars( pEnv, host);

		//syslog(LOG_ERR, "BR: regStr %s", regStr);

		// Since Java ints are defined to be big-endian, we de-canonicalize 'port' from a
		// big-endian number into a 16-bit pattern here.
		uint16_t	portBits = port;
		portBits = ( ((unsigned char*) &portBits)[0] << 8) | ((unsigned char*) &portBits)[1];

		pBytes = txtRecord ? (*pEnv)->GetByteArrayElements( pEnv, txtRecord, NULL) : NULL;
		numBytes = txtRecord ? (*pEnv)->GetArrayLength( pEnv, txtRecord) : 0;

		err = DNSServiceRegister( &pContext->ServiceRef, flags, ifIndex, servStr, regStr,
								domainStr, hostStr, portBits,
								numBytes, pBytes, ServiceRegisterReply, pContext);
		if ( err == kDNSServiceErr_NoError)
		{
			(*pEnv)->SetLongField( pEnv, pThis, contextField, (jlong) pContext);
		}

		if ( pBytes != NULL)
			(*pEnv)->ReleaseByteArrayElements( pEnv, txtRecord, pBytes, 0);

		SafeReleaseUTFChars( pEnv, serviceName, servStr);
		SafeReleaseUTFChars( pEnv, regType, regStr);
		SafeReleaseUTFChars( pEnv, domain, domainStr);
		SafeReleaseUTFChars( pEnv, host, hostStr);
	}
	else
		err = kDNSServiceErr_NoMemory;

	return err;
}

JNIEXPORT jint JNICALL Java_com_apple_dnssd_AppleRegistration_AddRecord( JNIEnv *pEnv, jobject pThis,
							jint flags, jint rrType, jbyteArray rData, jint ttl, jobject destObj)
{
	jclass					cls = (*pEnv)->GetObjectClass( pEnv, pThis);
	jfieldID				contextField = (*pEnv)->GetFieldID( pEnv, cls, "fNativeContext", "J");
	jclass					destCls = (*pEnv)->GetObjectClass( pEnv, destObj);
	jfieldID				recField = (*pEnv)->GetFieldID( pEnv, destCls, "fRecord", "J");
	OpContext				*pContext = NULL;
	DNSServiceErrorType		err = kDNSServiceErr_NoError;
	jbyte					*pBytes;
	jsize					numBytes;
	DNSRecordRef			recRef;

	if ( contextField != 0)
		pContext = (OpContext*) (*pEnv)->GetLongField( pEnv, pThis, contextField);
	if ( pContext == NULL || pContext->ServiceRef == NULL)
		return kDNSServiceErr_BadParam;

	pBytes = (*pEnv)->GetByteArrayElements( pEnv, rData, NULL);
	numBytes = (*pEnv)->GetArrayLength( pEnv, rData);

	err = DNSServiceAddRecord( pContext->ServiceRef, &recRef, flags, rrType, numBytes, pBytes, ttl);
	if ( err == kDNSServiceErr_NoError)
	{
		(*pEnv)->SetLongField( pEnv, destObj, recField, (jlong) recRef);
	}

	if ( pBytes != NULL)
		(*pEnv)->ReleaseByteArrayElements( pEnv, rData, pBytes, 0);

	return err;
}

JNIEXPORT jint JNICALL Java_com_apple_dnssd_AppleDNSRecord_Update( JNIEnv *pEnv, jobject pThis,
														jint flags, jbyteArray rData, jint ttl)
{
	jclass					cls = (*pEnv)->GetObjectClass( pEnv, pThis);
	jfieldID				ownerField = (*pEnv)->GetFieldID( pEnv, cls, "fOwner", "Lcom/apple/dnssd/AppleService;");
	jfieldID				recField = (*pEnv)->GetFieldID( pEnv, cls, "fRecord", "J");
	OpContext				*pContext = NULL;
	DNSServiceErrorType		err = kDNSServiceErr_NoError;
	jbyte					*pBytes;
	jsize					numBytes;
	DNSRecordRef			recRef = NULL;

	if ( ownerField != 0)
	{
		jobject		ownerObj = (*pEnv)->GetObjectField( pEnv, pThis, ownerField);
		jclass		ownerClass = (*pEnv)->GetObjectClass( pEnv, ownerObj);
		jfieldID	contextField = (*pEnv)->GetFieldID( pEnv, ownerClass, "fNativeContext", "J");
		if ( contextField != 0)
			pContext = (OpContext*) (*pEnv)->GetLongField( pEnv, ownerObj, contextField);
	}
	if ( recField != 0)
		recRef = (DNSRecordRef) (*pEnv)->GetLongField( pEnv, pThis, recField);
	if ( pContext == NULL || pContext->ServiceRef == NULL)
		return kDNSServiceErr_BadParam;

	pBytes = (*pEnv)->GetByteArrayElements( pEnv, rData, NULL);
	numBytes = (*pEnv)->GetArrayLength( pEnv, rData);

	err = DNSServiceUpdateRecord( pContext->ServiceRef, recRef, flags, numBytes, pBytes, ttl);

	if ( pBytes != NULL)
		(*pEnv)->ReleaseByteArrayElements( pEnv, rData, pBytes, 0);

	return err;
}

JNIEXPORT jint JNICALL Java_com_apple_dnssd_AppleDNSRecord_Remove( JNIEnv *pEnv, jobject pThis)
{
	jclass					cls = (*pEnv)->GetObjectClass( pEnv, pThis);
	jfieldID				ownerField = (*pEnv)->GetFieldID( pEnv, cls, "fOwner", "Lcom/apple/dnssd/AppleService;");
	jfieldID				recField = (*pEnv)->GetFieldID( pEnv, cls, "fRecord", "J");
	OpContext				*pContext = NULL;
	DNSServiceErrorType		err = kDNSServiceErr_NoError;
	DNSRecordRef			recRef = NULL;

	if ( ownerField != 0)
	{
		jobject		ownerObj = (*pEnv)->GetObjectField( pEnv, pThis, ownerField);
		jclass		ownerClass = (*pEnv)->GetObjectClass( pEnv, ownerObj);
		jfieldID	contextField = (*pEnv)->GetFieldID( pEnv, ownerClass, "fNativeContext", "J");
		if ( contextField != 0)
			pContext = (OpContext*) (*pEnv)->GetLongField( pEnv, ownerObj, contextField);
	}
	if ( recField != 0)
		recRef = (DNSRecordRef) (*pEnv)->GetLongField( pEnv, pThis, recField);
	if ( pContext == NULL || pContext->ServiceRef == NULL)
		return kDNSServiceErr_BadParam;

	err = DNSServiceRemoveRecord( pContext->ServiceRef, recRef, 0);

	return err;
}


JNIEXPORT jint JNICALL Java_com_apple_dnssd_AppleRecordRegistrar_CreateConnection( JNIEnv *pEnv, jobject pThis)
{
	jclass					cls = (*pEnv)->GetObjectClass( pEnv, pThis);
	jfieldID				contextField = (*pEnv)->GetFieldID( pEnv, cls, "fNativeContext", "J");
	OpContext				*pContext = NULL;
	DNSServiceErrorType		err = kDNSServiceErr_NoError;

	if ( contextField != 0)
		pContext = NewContext( pEnv, pThis, "recordRegistered", "(Lcom/apple/dnssd/DNSRecord;I)V");
	else
		err = kDNSServiceErr_BadParam;

	if ( pContext != NULL)
	{
		err = DNSServiceCreateConnection( &pContext->ServiceRef);
		if ( err == kDNSServiceErr_NoError)
		{
			(*pEnv)->SetLongField( pEnv, pThis, contextField, (jlong) pContext);
		}
	}
	else
		err = kDNSServiceErr_NoMemory;

	return err;
}

struct RecordRegistrationRef
{
	OpContext		*Context;
	jobject			RecordObj;
};
typedef struct RecordRegistrationRef	RecordRegistrationRef;

static void DNSSD_API	RegisterRecordReply( DNSServiceRef sdRef _UNUSED,
								DNSRecordRef recordRef _UNUSED, DNSServiceFlags flags,
								DNSServiceErrorType errorCode, void *context)
{
	RecordRegistrationRef	*regEnvelope = (RecordRegistrationRef*) context;
	OpContext		*pContext = regEnvelope->Context;

	SetupCallbackState( &pContext->Env);

	if ( pContext->ClientObj != NULL && pContext->Callback != NULL)
	{
		if ( errorCode == kDNSServiceErr_NoError)
		{
			(*pContext->Env)->CallVoidMethod( pContext->Env, pContext->ClientObj, pContext->Callback,
												regEnvelope->RecordObj, flags);
		}
		else
			ReportError( pContext->Env, pContext->ClientObj, pContext->JavaObj, errorCode);
	}

	(*pContext->Env)->DeleteWeakGlobalRef( pContext->Env, regEnvelope->RecordObj);
	free( regEnvelope);

	TeardownCallbackState();
}

JNIEXPORT jint JNICALL Java_com_apple_dnssd_AppleRecordRegistrar_RegisterRecord( JNIEnv *pEnv, jobject pThis,
							jint flags, jint ifIndex, jstring fullname, jint rrType, jint rrClass,
							jbyteArray rData, jint ttl, jobject destObj)
{
	jclass					cls = (*pEnv)->GetObjectClass( pEnv, pThis);
	jfieldID				contextField = (*pEnv)->GetFieldID( pEnv, cls, "fNativeContext", "J");
	jclass					destCls = (*pEnv)->GetObjectClass( pEnv, destObj);
	jfieldID				recField = (*pEnv)->GetFieldID( pEnv, destCls, "fRecord", "J");
	const char				*nameStr = SafeGetUTFChars( pEnv, fullname);
	OpContext				*pContext = NULL;
	DNSServiceErrorType		err = kDNSServiceErr_NoError;
	jbyte					*pBytes;
	jsize					numBytes;
	DNSRecordRef			recRef;
	RecordRegistrationRef	*regEnvelope;

	if ( contextField != 0)
		pContext = (OpContext*) (*pEnv)->GetLongField( pEnv, pThis, contextField);
	if ( pContext == NULL || pContext->ServiceRef == NULL || nameStr == NULL)
		return kDNSServiceErr_BadParam;

	regEnvelope = calloc( 1, sizeof *regEnvelope);
	if ( regEnvelope == NULL)
		return kDNSServiceErr_NoMemory;
	regEnvelope->Context = pContext;
	regEnvelope->RecordObj = (*pEnv)->NewWeakGlobalRef( pEnv, destObj);	// must convert local ref to global to cache

	pBytes = (*pEnv)->GetByteArrayElements( pEnv, rData, NULL);
	numBytes = (*pEnv)->GetArrayLength( pEnv, rData);

	err = DNSServiceRegisterRecord( pContext->ServiceRef, &recRef, flags, ifIndex,
									nameStr, rrType, rrClass, numBytes, pBytes, ttl,
									RegisterRecordReply, regEnvelope);

	if ( err == kDNSServiceErr_NoError)
	{
		(*pEnv)->SetLongField( pEnv, destObj, recField, (jlong) recRef);
	}
	else
	{
		if ( regEnvelope->RecordObj != NULL)
			(*pEnv)->DeleteWeakGlobalRef( pEnv, regEnvelope->RecordObj);
		free( regEnvelope);
	}

	if ( pBytes != NULL)
		(*pEnv)->ReleaseByteArrayElements( pEnv, rData, pBytes, 0);

	SafeReleaseUTFChars( pEnv, fullname, nameStr);

	return err;
}


static void DNSSD_API	ServiceQueryReply( DNSServiceRef sdRef _UNUSED, DNSServiceFlags flags, uint32_t interfaceIndex,
								DNSServiceErrorType errorCode, const char *serviceName,
								uint16_t rrtype, uint16_t rrclass, uint16_t rdlen,
								const void *rdata, uint32_t ttl, void *context)
{
	OpContext		*pContext = (OpContext*) context;
	jbyteArray		rDataObj;
	jbyte			*pBytes;

	SetupCallbackState( &pContext->Env);

	if ( pContext->ClientObj != NULL && pContext->Callback != NULL &&
		 NULL != ( rDataObj = (*pContext->Env)->NewByteArray( pContext->Env, rdlen)))
	{
		if ( errorCode == kDNSServiceErr_NoError)
		{
			// Initialize rDataObj with contents of rdata
			pBytes = (*pContext->Env)->GetByteArrayElements( pContext->Env, rDataObj, NULL);
			memcpy( pBytes, rdata, rdlen);
			(*pContext->Env)->ReleaseByteArrayElements( pContext->Env, rDataObj, pBytes, JNI_COMMIT);

			(*pContext->Env)->CallVoidMethod( pContext->Env, pContext->ClientObj, pContext->Callback,
								pContext->JavaObj, flags, interfaceIndex,
								(*pContext->Env)->NewStringUTF( pContext->Env, serviceName),
								rrtype, rrclass, rDataObj, ttl);
		}
		else
			ReportError( pContext->Env, pContext->ClientObj, pContext->JavaObj, errorCode);
	}
	TeardownCallbackState();
}

JNIEXPORT jint JNICALL Java_com_apple_dnssd_AppleQuery_CreateQuery( JNIEnv *pEnv, jobject pThis,
							jint flags, jint ifIndex, jstring serviceName, jint rrtype, jint rrclass)
{
	jclass					cls = (*pEnv)->GetObjectClass( pEnv, pThis);
	jfieldID				contextField = (*pEnv)->GetFieldID( pEnv, cls, "fNativeContext", "J");
	OpContext				*pContext = NULL;
	DNSServiceErrorType		err = kDNSServiceErr_NoError;

	if ( contextField != 0)
		pContext = NewContext( pEnv, pThis, "queryAnswered",
								"(Lcom/apple/dnssd/DNSSDService;IILjava/lang/String;II[BI)V");
	else
		err = kDNSServiceErr_BadParam;

	if ( pContext != NULL)
	{
		const char	*servStr = SafeGetUTFChars( pEnv, serviceName);

		err = DNSServiceQueryRecord( &pContext->ServiceRef, flags, ifIndex, servStr,
									rrtype, rrclass, ServiceQueryReply, pContext);
		if ( err == kDNSServiceErr_NoError)
		{
			(*pEnv)->SetLongField( pEnv, pThis, contextField, (jlong) pContext);
		}

		SafeReleaseUTFChars( pEnv, serviceName, servStr);
	}
	else
		err = kDNSServiceErr_NoMemory;

	return err;
}


static void DNSSD_API	DomainEnumReply( DNSServiceRef sdRef _UNUSED, DNSServiceFlags flags, uint32_t interfaceIndex,
								DNSServiceErrorType errorCode, const char *replyDomain, void *context)
{
	OpContext		*pContext = (OpContext*) context;

	SetupCallbackState( &pContext->Env);

	if ( pContext->ClientObj != NULL && pContext->Callback != NULL)
	{
		if ( errorCode == kDNSServiceErr_NoError)
		{
			(*pContext->Env)->CallVoidMethod( pContext->Env, pContext->ClientObj,
								( flags & kDNSServiceFlagsAdd) != 0 ? pContext->Callback : pContext->Callback2,
								pContext->JavaObj, flags, interfaceIndex,
								(*pContext->Env)->NewStringUTF( pContext->Env, replyDomain));
		}
		else
			ReportError( pContext->Env, pContext->ClientObj, pContext->JavaObj, errorCode);
	}
	TeardownCallbackState();
}

JNIEXPORT jint JNICALL Java_com_apple_dnssd_AppleDomainEnum_BeginEnum( JNIEnv *pEnv, jobject pThis,
							jint flags, jint ifIndex)
{
	jclass					cls = (*pEnv)->GetObjectClass( pEnv, pThis);
	jfieldID				contextField = (*pEnv)->GetFieldID( pEnv, cls, "fNativeContext", "J");
	OpContext				*pContext = NULL;
	DNSServiceErrorType		err = kDNSServiceErr_NoError;

	if ( contextField != 0)
		pContext = NewContext( pEnv, pThis, "domainFound",
								"(Lcom/apple/dnssd/DNSSDService;IILjava/lang/String;)V");
	else
		err = kDNSServiceErr_BadParam;

	if ( pContext != NULL)
	{
		pContext->Callback2 = (*pEnv)->GetMethodID( pEnv,
								(*pEnv)->GetObjectClass( pEnv, pContext->ClientObj),
								"domainLost", "(Lcom/apple/dnssd/DNSSDService;IILjava/lang/String;)V");

		err = DNSServiceEnumerateDomains( &pContext->ServiceRef, flags, ifIndex,
											DomainEnumReply, pContext);
		if ( err == kDNSServiceErr_NoError)
		{
			(*pEnv)->SetLongField( pEnv, pThis, contextField, (jlong) pContext);
		}
	}
	else
		err = kDNSServiceErr_NoMemory;

	return err;
}


JNIEXPORT jint JNICALL Java_com_apple_dnssd_AppleDNSSD_ConstructName( JNIEnv *pEnv, jobject pThis _UNUSED,
							jstring serviceName, jstring regtype, jstring domain, jobjectArray pOut)
{
	DNSServiceErrorType		err = kDNSServiceErr_NoError;
	const char				*nameStr = SafeGetUTFChars( pEnv, serviceName);
	const char				*regStr = SafeGetUTFChars( pEnv, regtype);
	const char				*domStr = SafeGetUTFChars( pEnv, domain);
	char					buff[ kDNSServiceMaxDomainName + 1];

	err = DNSServiceConstructFullName( buff, nameStr, regStr, domStr);

	if ( err == kDNSServiceErr_NoError)
	{
		// pOut is expected to be a String[1] array.
		(*pEnv)->SetObjectArrayElement( pEnv, pOut, 0, (*pEnv)->NewStringUTF( pEnv, buff));
	}

	SafeReleaseUTFChars( pEnv, serviceName, nameStr);
	SafeReleaseUTFChars( pEnv, regtype, regStr);
	SafeReleaseUTFChars( pEnv, domain, domStr);

	return err;
}

JNIEXPORT void JNICALL Java_com_apple_dnssd_AppleDNSSD_ReconfirmRecord( JNIEnv *pEnv, jobject pThis _UNUSED,
							jint flags, jint ifIndex, jstring fullName,
							jint rrtype, jint rrclass, jbyteArray rdata)
{
	jbyte					*pBytes;
	jsize					numBytes;
	const char				*nameStr = SafeGetUTFChars( pEnv, fullName);

	pBytes = (*pEnv)->GetByteArrayElements( pEnv, rdata, NULL);
	numBytes = (*pEnv)->GetArrayLength( pEnv, rdata);

	DNSServiceReconfirmRecord( flags, ifIndex, nameStr, rrtype, rrclass, numBytes, pBytes);

	if ( pBytes != NULL)
		(*pEnv)->ReleaseByteArrayElements( pEnv, rdata, pBytes, 0);

	SafeReleaseUTFChars( pEnv, fullName, nameStr);
}

#define LOCAL_ONLY_NAME "loo"

JNIEXPORT jstring JNICALL Java_com_apple_dnssd_AppleDNSSD_GetNameForIfIndex( JNIEnv *pEnv, jobject pThis _UNUSED,
							jint ifIndex)
{
	char					*p = LOCAL_ONLY_NAME, nameBuff[IF_NAMESIZE];

	if (ifIndex != (jint) kDNSServiceInterfaceIndexLocalOnly)
		p = if_indextoname( ifIndex, nameBuff );

	return (*pEnv)->NewStringUTF( pEnv, p);
}


JNIEXPORT jint JNICALL Java_com_apple_dnssd_AppleDNSSD_GetIfIndexForName( JNIEnv *pEnv, jobject pThis _UNUSED,
							jstring ifName)
{
	uint32_t				ifIndex = kDNSServiceInterfaceIndexLocalOnly;
	const char				*nameStr = SafeGetUTFChars( pEnv, ifName);

	if (strcmp(nameStr, LOCAL_ONLY_NAME))
		ifIndex = if_nametoindex( nameStr);

	SafeReleaseUTFChars( pEnv, ifName, nameStr);

	return ifIndex;
}


#if defined(_WIN32)
static char*
if_indextoname( DWORD ifIndex, char * nameBuff)
{
	PIP_ADAPTER_INFO	pAdapterInfo = NULL;
	PIP_ADAPTER_INFO	pAdapter = NULL;
	DWORD				dwRetVal = 0;
	char			*	ifName = NULL;
	ULONG				ulOutBufLen = 0;

	if (GetAdaptersInfo( NULL, &ulOutBufLen) != ERROR_BUFFER_OVERFLOW)
	{
		goto exit;
	}

	pAdapterInfo = (IP_ADAPTER_INFO *) malloc(ulOutBufLen);

	if (pAdapterInfo == NULL)
	{
		goto exit;
	}

	dwRetVal = GetAdaptersInfo( pAdapterInfo, &ulOutBufLen );

	if (dwRetVal != NO_ERROR)
	{
		goto exit;
	}

	pAdapter = pAdapterInfo;
	while (pAdapter)
	{
		if (pAdapter->Index == ifIndex)
		{
			// It would be better if we passed in the length of nameBuff to this
			// function, so we would have absolute certainty that no buffer
			// overflows would occur.  Buffer overflows *shouldn't* occur because
			// nameBuff is of size MAX_ADAPTER_NAME_LENGTH.
			strcpy( nameBuff, pAdapter->AdapterName );
			ifName = nameBuff;
			break;
		}

		pAdapter = pAdapter->Next;
	}

exit:

	if (pAdapterInfo != NULL)
	{
		free( pAdapterInfo );
		pAdapterInfo = NULL;
	}

	return ifName;
}


static DWORD
if_nametoindex( const char * nameStr )
{
	PIP_ADAPTER_INFO	pAdapterInfo = NULL;
	PIP_ADAPTER_INFO	pAdapter = NULL;
	DWORD				dwRetVal = 0;
	DWORD				ifIndex = 0;
	ULONG				ulOutBufLen = 0;

	if (GetAdaptersInfo( NULL, &ulOutBufLen) != ERROR_BUFFER_OVERFLOW)
	{
		goto exit;
	}

	pAdapterInfo = (IP_ADAPTER_INFO *) malloc(ulOutBufLen);

	if (pAdapterInfo == NULL)
	{
		goto exit;
	}

	dwRetVal = GetAdaptersInfo( pAdapterInfo, &ulOutBufLen );

	if (dwRetVal != NO_ERROR)
	{
		goto exit;
	}

	pAdapter = pAdapterInfo;
	while (pAdapter)
	{
		if (strcmp(pAdapter->AdapterName, nameStr) == 0)
		{
			ifIndex = pAdapter->Index;
			break;
		}

		pAdapter = pAdapter->Next;
	}

exit:

	if (pAdapterInfo != NULL)
	{
		free( pAdapterInfo );
		pAdapterInfo = NULL;
	}

	return ifIndex;
}
#endif