ares_android.c - platform/external/c-ares - Git at Google

 /* Copyright (C) 2017 by John Schember <john@nachtimwald.com>
  *
  * Permission to use, copy, modify, and distribute this
  * software and its documentation for any purpose and without
  * fee is hereby granted, provided that the above copyright
  * notice appear in all copies and that both that copyright
  * notice and this permission notice appear in supporting
  * documentation, and that the name of M.I.T. not be used in
  * advertising or publicity pertaining to distribution of the
  * software without specific, written prior permission.
  * M.I.T. makes no representations about the suitability of
  * this software for any purpose.  It is provided "as is"
  * without express or implied warranty.
  */
 #if defined(ANDROID) || defined(__ANDROID__)

 #include <jni.h>

 #include "ares_setup.h"
 #include "ares.h"
 #include "ares_android.h"
 #include "ares_private.h"

 static JavaVM *android_jvm = NULL;
 static jobject android_connectivity_manager = NULL;

 /* ConnectivityManager.getActiveNetwork */
 static jmethodID android_cm_active_net_mid = NULL;
 /* ConnectivityManager.getLinkProperties */
 static jmethodID android_cm_link_props_mid = NULL;
 /* LinkProperties.getDnsServers */
 static jmethodID android_lp_dns_servers_mid = NULL;
 /* LinkProperties.getDomains */
 static jmethodID android_lp_domains_mid = NULL;
 /* List.size */
 static jmethodID android_list_size_mid = NULL;
 /* List.get */
 static jmethodID android_list_get_mid = NULL;
 /* InetAddress.getHostAddress */
 static jmethodID android_ia_host_addr_mid = NULL;

 static jclass jni_get_class(JNIEnv *env, const char *path)
 {
   jclass cls = NULL;

   if (env == NULL || path == NULL || *path == '\0')
     return NULL;

   cls = (*env)->FindClass(env, path);
   if ((*env)->ExceptionOccurred(env)) {
     (*env)->ExceptionClear(env);
     return NULL;
   }
   return cls;
 }

 static jmethodID jni_get_method_id(JNIEnv *env, jclass cls,
                                    const char *func_name, const char *signature)
 {
   jmethodID mid = NULL;

   if (env == NULL || cls == NULL || func_name == NULL || *func_name == '\0' ||
           signature == NULL || *signature == '\0')
   {
     return NULL;
   }

   mid = (*env)->GetMethodID(env, cls, func_name, signature);
   if ((*env)->ExceptionOccurred(env))
   {
     (*env)->ExceptionClear(env);
     return NULL;
   }

   return mid;
 }

 void ares_library_init_jvm(JavaVM *jvm)
 {
   android_jvm = jvm;
 }

 int ares_library_init_android(jobject connectivity_manager)
 {
   JNIEnv *env = NULL;
   int need_detatch = 0;
   int res;
   int ret = ARES_ENOTINITIALIZED;
   jclass obj_cls = NULL;

   if (android_jvm == NULL)
     goto cleanup;

   res = (*android_jvm)->GetEnv(android_jvm, (void **)&env, JNI_VERSION_1_6);
   if (res == JNI_EDETACHED)
   {
     env = NULL;
     res = (*android_jvm)->AttachCurrentThread(android_jvm, &env, NULL);
     need_detatch = 1;
   }
   if (res != JNI_OK || env == NULL)
     goto cleanup;

   android_connectivity_manager =
       (*env)->NewGlobalRef(env, connectivity_manager);
   if (android_connectivity_manager == NULL)
     goto cleanup;

   /* Initialization has succeeded. Now attempt to cache the methods that will be
    * called by ares_get_android_server_list. */
   ret = ARES_SUCCESS;

   /* ConnectivityManager in API 1. */
   obj_cls = jni_get_class(env, "android/net/ConnectivityManager");
   if (obj_cls == NULL)
     goto cleanup;

   /* ConnectivityManager.getActiveNetwork in API 23. */
   android_cm_active_net_mid =
       jni_get_method_id(env, obj_cls, "getActiveNetwork",
                         "()Landroid/net/Network;");
   if (android_cm_active_net_mid == NULL)
     goto cleanup;

   /* ConnectivityManager.getLinkProperties in API 21. */
   android_cm_link_props_mid =
       jni_get_method_id(env, obj_cls, "getLinkProperties",
                         "(Landroid/net/Network;)Landroid/net/LinkProperties;");
   if (android_cm_link_props_mid == NULL)
     goto cleanup;

   /* LinkProperties in API 21. */
   (*env)->DeleteLocalRef(env, obj_cls);
   obj_cls = jni_get_class(env, "android/net/LinkProperties");
   if (obj_cls == NULL)
     goto cleanup;

   /* getDnsServers in API 21. */
   android_lp_dns_servers_mid = jni_get_method_id(env, obj_cls, "getDnsServers",
                                                  "()Ljava/util/List;");
   if (android_lp_dns_servers_mid == NULL)
     goto cleanup;

   /* getDomains in API 21. */
   android_lp_domains_mid = jni_get_method_id(env, obj_cls, "getDomains",
                                                  "()Ljava/lang/String;");
   if (android_lp_domains_mid == NULL)
     goto cleanup;

   (*env)->DeleteLocalRef(env, obj_cls);
   obj_cls = jni_get_class(env, "java/util/List");
   if (obj_cls == NULL)
     goto cleanup;

   android_list_size_mid = jni_get_method_id(env, obj_cls, "size", "()I");
   if (android_list_size_mid == NULL)
     goto cleanup;

   android_list_get_mid = jni_get_method_id(env, obj_cls, "get",
                                            "(I)Ljava/lang/Object;");
   if (android_list_get_mid == NULL)
     goto cleanup;

   (*env)->DeleteLocalRef(env, obj_cls);
   obj_cls = jni_get_class(env, "java/net/InetAddress");
   if (obj_cls == NULL)
     goto cleanup;

   android_ia_host_addr_mid = jni_get_method_id(env, obj_cls, "getHostAddress",
                                                "()Ljava/lang/String;");
   if (android_ia_host_addr_mid == NULL)
     goto cleanup;

   (*env)->DeleteLocalRef(env, obj_cls);
   goto done;

 cleanup:
   if (obj_cls != NULL)
     (*env)->DeleteLocalRef(env, obj_cls);

   android_cm_active_net_mid = NULL;
   android_cm_link_props_mid = NULL;
   android_lp_dns_servers_mid = NULL;
   android_lp_domains_mid = NULL;
   android_list_size_mid = NULL;
   android_list_get_mid = NULL;
   android_ia_host_addr_mid = NULL;

 done:
   if (need_detatch)
     (*android_jvm)->DetachCurrentThread(android_jvm);

   return ret;
 }

 int ares_library_android_initialized(void)
 {
   if (android_jvm == NULL || android_connectivity_manager == NULL)
     return ARES_ENOTINITIALIZED;
   return ARES_SUCCESS;
 }

 void ares_library_cleanup_android(void)
 {
   JNIEnv *env = NULL;
   int need_detatch = 0;
   int res;

   if (android_jvm == NULL || android_connectivity_manager == NULL)
     return;

   res = (*android_jvm)->GetEnv(android_jvm, (void **)&env, JNI_VERSION_1_6);
   if (res == JNI_EDETACHED)
   {
     env = NULL;
     res = (*android_jvm)->AttachCurrentThread(android_jvm, &env, NULL);
     need_detatch = 1;
   }
   if (res != JNI_OK || env == NULL)
     return;

   android_cm_active_net_mid = NULL;
   android_cm_link_props_mid = NULL;
   android_lp_dns_servers_mid = NULL;
   android_lp_domains_mid = NULL;
   android_list_size_mid = NULL;
   android_list_get_mid = NULL;
   android_ia_host_addr_mid = NULL;

   (*env)->DeleteGlobalRef(env, android_connectivity_manager);
   android_connectivity_manager = NULL;

   if (need_detatch)
     (*android_jvm)->DetachCurrentThread(android_jvm);
 }

 char **ares_get_android_server_list(size_t max_servers,
                                     size_t *num_servers)
 {
   JNIEnv *env = NULL;
   jobject active_network = NULL;
   jobject link_properties = NULL;
   jobject server_list = NULL;
   jobject server = NULL;
   jstring str = NULL;
   jint nserv;
   const char *ch_server_address;
   int res;
   size_t i;
   char **dns_list = NULL;
   int need_detatch = 0;

   if (android_jvm == NULL || android_connectivity_manager == NULL ||
           max_servers == 0 || num_servers == NULL)
   {
     return NULL;
   }

   if (android_cm_active_net_mid == NULL || android_cm_link_props_mid == NULL ||
       android_lp_dns_servers_mid == NULL || android_list_size_mid == NULL ||
       android_list_get_mid == NULL || android_ia_host_addr_mid == NULL)
   {
     return NULL;
   }

   res = (*android_jvm)->GetEnv(android_jvm, (void **)&env, JNI_VERSION_1_6);
   if (res == JNI_EDETACHED)
   {
     env = NULL;
     res = (*android_jvm)->AttachCurrentThread(android_jvm, &env, NULL);
     need_detatch = 1;
   }
   if (res != JNI_OK || env == NULL)
     goto done;

   /* JNI below is equivalent to this Java code.
      import android.content.Context;
      import android.net.ConnectivityManager;
      import android.net.LinkProperties;
      import android.net.Network;
      import java.net.InetAddress;
      import java.util.List;

      ConnectivityManager cm = (ConnectivityManager)this.getApplicationContext()
        .getSystemService(Context.CONNECTIVITY_SERVICE);
      Network an = cm.getActiveNetwork();
      LinkProperties lp = cm.getLinkProperties(an);
      List<InetAddress> dns = lp.getDnsServers();
      for (InetAddress ia: dns) {
        String ha = ia.getHostAddress();
      }

      Note: The JNI ConnectivityManager object and all method IDs were previously
            initialized in ares_library_init_android.
    */

   active_network = (*env)->CallObjectMethod(env, android_connectivity_manager,
                                             android_cm_active_net_mid);
   if (active_network == NULL)
     goto done;

   link_properties =
       (*env)->CallObjectMethod(env, android_connectivity_manager,
                                android_cm_link_props_mid, active_network);
   if (link_properties == NULL)
     goto done;

   server_list = (*env)->CallObjectMethod(env, link_properties,
                                          android_lp_dns_servers_mid);
   if (server_list == NULL)
     goto done;

   nserv = (*env)->CallIntMethod(env, server_list, android_list_size_mid);
   if (nserv > (jint)max_servers)
     nserv = (jint)max_servers;
   if (nserv <= 0)
     goto done;
   *num_servers = (size_t)nserv;

   dns_list = ares_malloc(sizeof(*dns_list)*(*num_servers));
   for (i=0; i<*num_servers; i++)
   {
     server = (*env)->CallObjectMethod(env, server_list, android_list_get_mid,
                                       (jint)i);
     dns_list[i] = ares_malloc(64);
     dns_list[i][0] = 0;
     if (server == NULL)
     {
       continue;
     }
     str = (*env)->CallObjectMethod(env, server, android_ia_host_addr_mid);
     ch_server_address = (*env)->GetStringUTFChars(env, str, 0);
     strncpy(dns_list[i], ch_server_address, 64);
     (*env)->ReleaseStringUTFChars(env, str, ch_server_address);
     (*env)->DeleteLocalRef(env, str);
     (*env)->DeleteLocalRef(env, server);
   }

 done:
   if ((*env)->ExceptionOccurred(env))
     (*env)->ExceptionClear(env);

   if (server_list != NULL)
     (*env)->DeleteLocalRef(env, server_list);
   if (link_properties != NULL)
     (*env)->DeleteLocalRef(env, link_properties);
   if (active_network != NULL)
     (*env)->DeleteLocalRef(env, active_network);

   if (need_detatch)
     (*android_jvm)->DetachCurrentThread(android_jvm);
   return dns_list;
 }

 char *ares_get_android_search_domains_list(void)
 {
   JNIEnv *env = NULL;
   jobject active_network = NULL;
   jobject link_properties = NULL;
   jstring domains = NULL;
   const char *domain;
   int res;
   size_t i;
   size_t cnt = 0;
   char *domain_list = NULL;
   int need_detatch = 0;

   if (android_jvm == NULL || android_connectivity_manager == NULL)
   {
     return NULL;
   }

   if (android_cm_active_net_mid == NULL || android_cm_link_props_mid == NULL ||
       android_lp_domains_mid == NULL)
   {
     return NULL;
   }

   res = (*android_jvm)->GetEnv(android_jvm, (void **)&env, JNI_VERSION_1_6);
   if (res == JNI_EDETACHED)
   {
     env = NULL;
     res = (*android_jvm)->AttachCurrentThread(android_jvm, &env, NULL);
     need_detatch = 1;
   }
   if (res != JNI_OK || env == NULL)
     goto done;

   /* JNI below is equivalent to this Java code.
      import android.content.Context;
      import android.net.ConnectivityManager;
      import android.net.LinkProperties;

      ConnectivityManager cm = (ConnectivityManager)this.getApplicationContext()
        .getSystemService(Context.CONNECTIVITY_SERVICE);
      Network an = cm.getActiveNetwork();
      LinkProperties lp = cm.getLinkProperties(an);
 	 String domains = lp.getDomains();
      for (String domain: domains.split(",")) {
        String d = domain;
      }

      Note: The JNI ConnectivityManager object and all method IDs were previously
            initialized in ares_library_init_android.
    */

   active_network = (*env)->CallObjectMethod(env, android_connectivity_manager,
                                             android_cm_active_net_mid);
   if (active_network == NULL)
     goto done;

   link_properties =
       (*env)->CallObjectMethod(env, android_connectivity_manager,
                                android_cm_link_props_mid, active_network);
   if (link_properties == NULL)
     goto done;

   /* Get the domains. It is a common separated list of domains to search. */
   domains = (*env)->CallObjectMethod(env, link_properties,
                                          android_lp_domains_mid);
   if (domains == NULL)
     goto done;

   /* Split on , */
   domain = (*env)->GetStringUTFChars(env, domains, 0);
   domain_list = ares_strdup(domain);
   (*env)->ReleaseStringUTFChars(env, domains, domain);
   (*env)->DeleteLocalRef(env, domains);

 done:
   if ((*env)->ExceptionOccurred(env))
     (*env)->ExceptionClear(env);

   if (link_properties != NULL)
     (*env)->DeleteLocalRef(env, link_properties);
   if (active_network != NULL)
     (*env)->DeleteLocalRef(env, active_network);

   if (need_detatch)
     (*android_jvm)->DetachCurrentThread(android_jvm);
   return domain_list;
 }
 #else
 /* warning: ISO C forbids an empty translation unit */
 typedef int dummy_make_iso_compilers_happy;
 #endif
	/* Copyright (C) 2017 by John Schember <john@nachtimwald.com>
	*
	* Permission to use, copy, modify, and distribute this
	* software and its documentation for any purpose and without
	* fee is hereby granted, provided that the above copyright
	* notice appear in all copies and that both that copyright
	* notice and this permission notice appear in supporting
	* documentation, and that the name of M.I.T. not be used in
	* advertising or publicity pertaining to distribution of the
	* software without specific, written prior permission.
	* M.I.T. makes no representations about the suitability of
	* this software for any purpose. It is provided "as is"
	* without express or implied warranty.
	*/
	#if defined(ANDROID) \|\| defined(__ANDROID__)

	#include <jni.h>

	#include "ares_setup.h"
	#include "ares.h"
	#include "ares_android.h"
	#include "ares_private.h"

	static JavaVM *android_jvm = NULL;
	static jobject android_connectivity_manager = NULL;

	/* ConnectivityManager.getActiveNetwork */
	static jmethodID android_cm_active_net_mid = NULL;
	/* ConnectivityManager.getLinkProperties */
	static jmethodID android_cm_link_props_mid = NULL;
	/* LinkProperties.getDnsServers */
	static jmethodID android_lp_dns_servers_mid = NULL;
	/* LinkProperties.getDomains */
	static jmethodID android_lp_domains_mid = NULL;
	/* List.size */
	static jmethodID android_list_size_mid = NULL;
	/* List.get */
	static jmethodID android_list_get_mid = NULL;
	/* InetAddress.getHostAddress */
	static jmethodID android_ia_host_addr_mid = NULL;

	static jclass jni_get_class(JNIEnv env, const char path)
	{
	jclass cls = NULL;

	if (env == NULL \|\| path == NULL \|\| *path == '\0')
	return NULL;

	cls = (*env)->FindClass(env, path);
	if ((*env)->ExceptionOccurred(env)) {
	(*env)->ExceptionClear(env);
	return NULL;
	}
	return cls;
	}

	static jmethodID jni_get_method_id(JNIEnv *env, jclass cls,
	const char func_name, const char signature)
	{
	jmethodID mid = NULL;

	if (env == NULL \|\| cls == NULL \|\| func_name == NULL \|\| *func_name == '\0' \|\|
	signature == NULL \|\| *signature == '\0')
	{
	return NULL;
	}

	mid = (*env)->GetMethodID(env, cls, func_name, signature);
	if ((*env)->ExceptionOccurred(env))
	{
	(*env)->ExceptionClear(env);
	return NULL;
	}

	return mid;
	}

	void ares_library_init_jvm(JavaVM *jvm)
	{
	android_jvm = jvm;
	}

	int ares_library_init_android(jobject connectivity_manager)
	{
	JNIEnv *env = NULL;
	int need_detatch = 0;
	int res;
	int ret = ARES_ENOTINITIALIZED;
	jclass obj_cls = NULL;

	if (android_jvm == NULL)
	goto cleanup;

	res = (android_jvm)->GetEnv(android_jvm, (void *)&env, JNI_VERSION_1_6);
	if (res == JNI_EDETACHED)
	{
	env = NULL;
	res = (*android_jvm)->AttachCurrentThread(android_jvm, &env, NULL);
	need_detatch = 1;
	}
	if (res != JNI_OK \|\| env == NULL)
	goto cleanup;

	android_connectivity_manager =
	(*env)->NewGlobalRef(env, connectivity_manager);
	if (android_connectivity_manager == NULL)
	goto cleanup;

	/* Initialization has succeeded. Now attempt to cache the methods that will be
	* called by ares_get_android_server_list. */
	ret = ARES_SUCCESS;

	/* ConnectivityManager in API 1. */
	obj_cls = jni_get_class(env, "android/net/ConnectivityManager");
	if (obj_cls == NULL)
	goto cleanup;

	/* ConnectivityManager.getActiveNetwork in API 23. */
	android_cm_active_net_mid =
	jni_get_method_id(env, obj_cls, "getActiveNetwork",
	"()Landroid/net/Network;");
	if (android_cm_active_net_mid == NULL)
	goto cleanup;

	/* ConnectivityManager.getLinkProperties in API 21. */
	android_cm_link_props_mid =
	jni_get_method_id(env, obj_cls, "getLinkProperties",
	"(Landroid/net/Network;)Landroid/net/LinkProperties;");
	if (android_cm_link_props_mid == NULL)
	goto cleanup;

	/* LinkProperties in API 21. */
	(*env)->DeleteLocalRef(env, obj_cls);
	obj_cls = jni_get_class(env, "android/net/LinkProperties");
	if (obj_cls == NULL)
	goto cleanup;

	/* getDnsServers in API 21. */
	android_lp_dns_servers_mid = jni_get_method_id(env, obj_cls, "getDnsServers",
	"()Ljava/util/List;");
	if (android_lp_dns_servers_mid == NULL)
	goto cleanup;

	/* getDomains in API 21. */
	android_lp_domains_mid = jni_get_method_id(env, obj_cls, "getDomains",
	"()Ljava/lang/String;");
	if (android_lp_domains_mid == NULL)
	goto cleanup;

	(*env)->DeleteLocalRef(env, obj_cls);
	obj_cls = jni_get_class(env, "java/util/List");
	if (obj_cls == NULL)
	goto cleanup;

	android_list_size_mid = jni_get_method_id(env, obj_cls, "size", "()I");
	if (android_list_size_mid == NULL)
	goto cleanup;

	android_list_get_mid = jni_get_method_id(env, obj_cls, "get",
	"(I)Ljava/lang/Object;");
	if (android_list_get_mid == NULL)
	goto cleanup;

	(*env)->DeleteLocalRef(env, obj_cls);
	obj_cls = jni_get_class(env, "java/net/InetAddress");
	if (obj_cls == NULL)
	goto cleanup;

	android_ia_host_addr_mid = jni_get_method_id(env, obj_cls, "getHostAddress",
	"()Ljava/lang/String;");
	if (android_ia_host_addr_mid == NULL)
	goto cleanup;

	(*env)->DeleteLocalRef(env, obj_cls);
	goto done;

	cleanup:
	if (obj_cls != NULL)
	(*env)->DeleteLocalRef(env, obj_cls);

	android_cm_active_net_mid = NULL;
	android_cm_link_props_mid = NULL;
	android_lp_dns_servers_mid = NULL;
	android_lp_domains_mid = NULL;
	android_list_size_mid = NULL;
	android_list_get_mid = NULL;
	android_ia_host_addr_mid = NULL;

	done:
	if (need_detatch)
	(*android_jvm)->DetachCurrentThread(android_jvm);

	return ret;
	}

	int ares_library_android_initialized(void)
	{
	if (android_jvm == NULL \|\| android_connectivity_manager == NULL)
	return ARES_ENOTINITIALIZED;
	return ARES_SUCCESS;
	}

	void ares_library_cleanup_android(void)
	{
	JNIEnv *env = NULL;
	int need_detatch = 0;
	int res;

	if (android_jvm == NULL \|\| android_connectivity_manager == NULL)
	return;

	res = (android_jvm)->GetEnv(android_jvm, (void *)&env, JNI_VERSION_1_6);
	if (res == JNI_EDETACHED)
	{
	env = NULL;
	res = (*android_jvm)->AttachCurrentThread(android_jvm, &env, NULL);
	need_detatch = 1;
	}
	if (res != JNI_OK \|\| env == NULL)
	return;

	android_cm_active_net_mid = NULL;
	android_cm_link_props_mid = NULL;
	android_lp_dns_servers_mid = NULL;
	android_lp_domains_mid = NULL;
	android_list_size_mid = NULL;
	android_list_get_mid = NULL;
	android_ia_host_addr_mid = NULL;

	(*env)->DeleteGlobalRef(env, android_connectivity_manager);
	android_connectivity_manager = NULL;

	if (need_detatch)
	(*android_jvm)->DetachCurrentThread(android_jvm);
	}

	char **ares_get_android_server_list(size_t max_servers,
	size_t *num_servers)
	{
	JNIEnv *env = NULL;
	jobject active_network = NULL;
	jobject link_properties = NULL;
	jobject server_list = NULL;
	jobject server = NULL;
	jstring str = NULL;
	jint nserv;
	const char *ch_server_address;
	int res;
	size_t i;
	char **dns_list = NULL;
	int need_detatch = 0;

	if (android_jvm == NULL \|\| android_connectivity_manager == NULL \|\|
	max_servers == 0 \|\| num_servers == NULL)
	{
	return NULL;
	}

	if (android_cm_active_net_mid == NULL \|\| android_cm_link_props_mid == NULL \|\|
	android_lp_dns_servers_mid == NULL \|\| android_list_size_mid == NULL \|\|
	android_list_get_mid == NULL \|\| android_ia_host_addr_mid == NULL)
	{
	return NULL;
	}

	res = (android_jvm)->GetEnv(android_jvm, (void *)&env, JNI_VERSION_1_6);
	if (res == JNI_EDETACHED)
	{
	env = NULL;
	res = (*android_jvm)->AttachCurrentThread(android_jvm, &env, NULL);
	need_detatch = 1;
	}
	if (res != JNI_OK \|\| env == NULL)
	goto done;

	/* JNI below is equivalent to this Java code.
	import android.content.Context;
	import android.net.ConnectivityManager;
	import android.net.LinkProperties;
	import android.net.Network;
	import java.net.InetAddress;
	import java.util.List;

	ConnectivityManager cm = (ConnectivityManager)this.getApplicationContext()
	.getSystemService(Context.CONNECTIVITY_SERVICE);
	Network an = cm.getActiveNetwork();
	LinkProperties lp = cm.getLinkProperties(an);
	List<InetAddress> dns = lp.getDnsServers();
	for (InetAddress ia: dns) {
	String ha = ia.getHostAddress();
	}

	Note: The JNI ConnectivityManager object and all method IDs were previously
	initialized in ares_library_init_android.
	*/

	active_network = (*env)->CallObjectMethod(env, android_connectivity_manager,
	android_cm_active_net_mid);
	if (active_network == NULL)
	goto done;

	link_properties =
	(*env)->CallObjectMethod(env, android_connectivity_manager,
	android_cm_link_props_mid, active_network);
	if (link_properties == NULL)
	goto done;

	server_list = (*env)->CallObjectMethod(env, link_properties,
	android_lp_dns_servers_mid);
	if (server_list == NULL)
	goto done;

	nserv = (*env)->CallIntMethod(env, server_list, android_list_size_mid);
	if (nserv > (jint)max_servers)
	nserv = (jint)max_servers;
	if (nserv <= 0)
	goto done;
	*num_servers = (size_t)nserv;

	dns_list = ares_malloc(sizeof(dns_list)(*num_servers));
	for (i=0; i<*num_servers; i++)
	{
	server = (*env)->CallObjectMethod(env, server_list, android_list_get_mid,
	(jint)i);
	dns_list[i] = ares_malloc(64);
	dns_list[i][0] = 0;
	if (server == NULL)
	{
	continue;
	}
	str = (*env)->CallObjectMethod(env, server, android_ia_host_addr_mid);
	ch_server_address = (*env)->GetStringUTFChars(env, str, 0);
	strncpy(dns_list[i], ch_server_address, 64);
	(*env)->ReleaseStringUTFChars(env, str, ch_server_address);
	(*env)->DeleteLocalRef(env, str);
	(*env)->DeleteLocalRef(env, server);
	}

	done:
	if ((*env)->ExceptionOccurred(env))
	(*env)->ExceptionClear(env);

	if (server_list != NULL)
	(*env)->DeleteLocalRef(env, server_list);
	if (link_properties != NULL)
	(*env)->DeleteLocalRef(env, link_properties);
	if (active_network != NULL)
	(*env)->DeleteLocalRef(env, active_network);

	if (need_detatch)
	(*android_jvm)->DetachCurrentThread(android_jvm);
	return dns_list;
	}

	char *ares_get_android_search_domains_list(void)
	{
	JNIEnv *env = NULL;
	jobject active_network = NULL;
	jobject link_properties = NULL;
	jstring domains = NULL;
	const char *domain;
	int res;
	size_t i;
	size_t cnt = 0;
	char *domain_list = NULL;
	int need_detatch = 0;

	if (android_jvm == NULL \|\| android_connectivity_manager == NULL)
	{
	return NULL;
	}

	if (android_cm_active_net_mid == NULL \|\| android_cm_link_props_mid == NULL \|\|
	android_lp_domains_mid == NULL)
	{
	return NULL;
	}

	res = (android_jvm)->GetEnv(android_jvm, (void *)&env, JNI_VERSION_1_6);
	if (res == JNI_EDETACHED)
	{
	env = NULL;
	res = (*android_jvm)->AttachCurrentThread(android_jvm, &env, NULL);
	need_detatch = 1;
	}
	if (res != JNI_OK \|\| env == NULL)
	goto done;

	/* JNI below is equivalent to this Java code.
	import android.content.Context;
	import android.net.ConnectivityManager;
	import android.net.LinkProperties;

	ConnectivityManager cm = (ConnectivityManager)this.getApplicationContext()
	.getSystemService(Context.CONNECTIVITY_SERVICE);
	Network an = cm.getActiveNetwork();
	LinkProperties lp = cm.getLinkProperties(an);
	String domains = lp.getDomains();
	for (String domain: domains.split(",")) {
	String d = domain;
	}

	Note: The JNI ConnectivityManager object and all method IDs were previously
	initialized in ares_library_init_android.
	*/

	active_network = (*env)->CallObjectMethod(env, android_connectivity_manager,
	android_cm_active_net_mid);
	if (active_network == NULL)
	goto done;

	link_properties =
	(*env)->CallObjectMethod(env, android_connectivity_manager,
	android_cm_link_props_mid, active_network);
	if (link_properties == NULL)
	goto done;

	/* Get the domains. It is a common separated list of domains to search. */
	domains = (*env)->CallObjectMethod(env, link_properties,
	android_lp_domains_mid);
	if (domains == NULL)
	goto done;

	/* Split on , */
	domain = (*env)->GetStringUTFChars(env, domains, 0);
	domain_list = ares_strdup(domain);
	(*env)->ReleaseStringUTFChars(env, domains, domain);
	(*env)->DeleteLocalRef(env, domains);

	done:
	if ((*env)->ExceptionOccurred(env))
	(*env)->ExceptionClear(env);

	if (link_properties != NULL)
	(*env)->DeleteLocalRef(env, link_properties);
	if (active_network != NULL)
	(*env)->DeleteLocalRef(env, active_network);

	if (need_detatch)
	(*android_jvm)->DetachCurrentThread(android_jvm);
	return domain_list;
	}
	#else
	/* warning: ISO C forbids an empty translation unit */
	typedef int dummy_make_iso_compilers_happy;
	#endif