src/java.base/unix/native/libnet/Inet4AddressImpl.c - platform/libcore - Git at Google

 /*
  * Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.  Oracle designates this
  * particular file as subject to the "Classpath" exception as provided
  * by Oracle in the LICENSE file that accompanied this code.
  *
  * This code 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 General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  */
 #include <ctype.h>
 #include <errno.h>
 #include <sys/types.h>
 #include <netinet/in.h>
 #include <netinet/in_systm.h>
 #include <netinet/ip.h>
 #include <netinet/ip_icmp.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/time.h>

 #include "net_util.h"

 #include "java_net_Inet4AddressImpl.h"

 #if defined(MACOSX)
 extern jobjectArray lookupIfLocalhost(JNIEnv *env, const char *hostname, jboolean includeV6);
 #endif

 #define SET_NONBLOCKING(fd) {       \
     int flags = fcntl(fd, F_GETFL); \
     flags |= O_NONBLOCK;            \
     fcntl(fd, F_SETFL, flags);      \
 }

 /*
  * Inet4AddressImpl
  */

 /*
  * Class:     java_net_Inet4AddressImpl
  * Method:    getLocalHostName
  * Signature: ()Ljava/lang/String;
  */
 JNIEXPORT jstring JNICALL
 Java_java_net_Inet4AddressImpl_getLocalHostName(JNIEnv *env, jobject this) {
     char hostname[NI_MAXHOST + 1];

     hostname[0] = '\0';
     if (gethostname(hostname, sizeof(hostname)) != 0) {
         strcpy(hostname, "localhost");
     } else {
 #if defined(__solaris__)
         // try to resolve hostname via nameservice
         // if it is known but getnameinfo fails, hostname will still be the
         // value from gethostname
         struct addrinfo hints, *res;

         // make sure string is null-terminated
         hostname[NI_MAXHOST] = '\0';
         memset(&hints, 0, sizeof(hints));
         hints.ai_flags = AI_CANONNAME;
         hints.ai_family = AF_INET;

         if (getaddrinfo(hostname, NULL, &hints, &res) == 0) {
             getnameinfo(res->ai_addr, res->ai_addrlen, hostname, sizeof(hostname),
                         NULL, 0, NI_NAMEREQD);
             freeaddrinfo(res);
         }
 #else
         // make sure string is null-terminated
         hostname[NI_MAXHOST] = '\0';
 #endif
     }
     return (*env)->NewStringUTF(env, hostname);
 }

 /*
  * Find an internet address for a given hostname. Note that this
  * code only works for addresses of type INET. The translation
  * of %d.%d.%d.%d to an address (int) occurs in java now, so the
  * String "host" shouldn't be a %d.%d.%d.%d string. The only
  * exception should be when any of the %d are out of range and
  * we fallback to a lookup.
  *
  * Class:     java_net_Inet4AddressImpl
  * Method:    lookupAllHostAddr
  * Signature: (Ljava/lang/String;)[[B
  */
 JNIEXPORT jobjectArray JNICALL
 Java_java_net_Inet4AddressImpl_lookupAllHostAddr(JNIEnv *env, jobject this,
                                                  jstring host) {
     jobjectArray ret = NULL;
     const char *hostname;
     int error = 0;
     struct addrinfo hints, *res = NULL, *resNew = NULL, *last = NULL,
         *iterator;

     initInetAddressIDs(env);
     JNU_CHECK_EXCEPTION_RETURN(env, NULL);

     if (IS_NULL(host)) {
         JNU_ThrowNullPointerException(env, "host argument is null");
         return NULL;
     }
     hostname = JNU_GetStringPlatformChars(env, host, JNI_FALSE);
     CHECK_NULL_RETURN(hostname, NULL);

     // try once, with our static buffer
     memset(&hints, 0, sizeof(hints));
     hints.ai_flags = AI_CANONNAME;
     hints.ai_family = AF_INET;

     error = getaddrinfo(hostname, NULL, &hints, &res);

     if (error) {
 #if defined(MACOSX)
         // If getaddrinfo fails try getifaddrs, see bug 8170910.
         ret = lookupIfLocalhost(env, hostname, JNI_FALSE);
         if (ret != NULL || (*env)->ExceptionCheck(env)) {
             goto cleanupAndReturn;
         }
 #endif
         // report error
         NET_ThrowUnknownHostExceptionWithGaiError(env, hostname, error);
         goto cleanupAndReturn;
     } else {
         int i = 0;
         iterator = res;
         while (iterator != NULL) {
             // skip duplicates
             int skip = 0;
             struct addrinfo *iteratorNew = resNew;
             while (iteratorNew != NULL) {
                 struct sockaddr_in *addr1, *addr2;
                 addr1 = (struct sockaddr_in *)iterator->ai_addr;
                 addr2 = (struct sockaddr_in *)iteratorNew->ai_addr;
                 if (addr1->sin_addr.s_addr == addr2->sin_addr.s_addr) {
                     skip = 1;
                     break;
                 }
                 iteratorNew = iteratorNew->ai_next;
             }

             if (!skip) {
                 struct addrinfo *next
                     = (struct addrinfo *)malloc(sizeof(struct addrinfo));
                 if (!next) {
                     JNU_ThrowOutOfMemoryError(env, "Native heap allocation failed");
                     ret = NULL;
                     goto cleanupAndReturn;
                 }
                 memcpy(next, iterator, sizeof(struct addrinfo));
                 next->ai_next = NULL;
                 if (resNew == NULL) {
                     resNew = next;
                 } else {
                     last->ai_next = next;
                 }
                 last = next;
                 i++;
             }
             iterator = iterator->ai_next;
         }

         // allocate array - at this point i contains the number of addresses
         ret = (*env)->NewObjectArray(env, i, ia_class, NULL);
         if (IS_NULL(ret)) {
             goto cleanupAndReturn;
         }

         i = 0;
         iterator = resNew;
         while (iterator != NULL) {
             jobject iaObj = (*env)->NewObject(env, ia4_class, ia4_ctrID);
             if (IS_NULL(iaObj)) {
                 ret = NULL;
                 goto cleanupAndReturn;
             }
             setInetAddress_addr(env, iaObj, ntohl(((struct sockaddr_in *)
                                 (iterator->ai_addr))->sin_addr.s_addr));
             if ((*env)->ExceptionCheck(env))
                 goto cleanupAndReturn;
             setInetAddress_hostName(env, iaObj, host);
             if ((*env)->ExceptionCheck(env))
                 goto cleanupAndReturn;
             (*env)->SetObjectArrayElement(env, ret, i++, iaObj);
             iterator = iterator->ai_next;
         }
     }
 cleanupAndReturn:
     JNU_ReleaseStringPlatformChars(env, host, hostname);
     while (resNew != NULL) {
         last = resNew;
         resNew = resNew->ai_next;
         free(last);
     }
     if (res != NULL) {
         freeaddrinfo(res);
     }
     return ret;
 }

 /*
  * Class:     java_net_Inet4AddressImpl
  * Method:    getHostByAddr
  * Signature: (I)Ljava/lang/String;
  *
  * Theoretically the UnknownHostException could be enriched with gai error
  * information. But as it is silently ignored anyway, there's no need for this.
  * It's only important that either a valid hostname is returned or an
  * UnknownHostException is thrown.
  */
 JNIEXPORT jstring JNICALL
 Java_java_net_Inet4AddressImpl_getHostByAddr(JNIEnv *env, jobject this,
                                              jbyteArray addrArray) {
     jstring ret = NULL;
     char host[NI_MAXHOST + 1];
     jbyte caddr[4];
     jint addr;
     struct sockaddr_in sa;

     // construct a sockaddr_in structure
     memset((char *)&sa, 0, sizeof(struct sockaddr_in));
     (*env)->GetByteArrayRegion(env, addrArray, 0, 4, caddr);
     addr = ((caddr[0] << 24) & 0xff000000);
     addr |= ((caddr[1] << 16) & 0xff0000);
     addr |= ((caddr[2] << 8) & 0xff00);
     addr |= (caddr[3] & 0xff);
     sa.sin_addr.s_addr = htonl(addr);
     sa.sin_family = AF_INET;

     if (getnameinfo((struct sockaddr *)&sa, sizeof(struct sockaddr_in),
                     host, sizeof(host), NULL, 0, NI_NAMEREQD)) {
         JNU_ThrowByName(env, "java/net/UnknownHostException", NULL);
     } else {
         ret = (*env)->NewStringUTF(env, host);
         if (ret == NULL) {
             JNU_ThrowByName(env, "java/net/UnknownHostException", NULL);
         }
     }

     return ret;
 }

 /**
  * ping implementation using tcp port 7 (echo)
  */
 static jboolean
 tcp_ping4(JNIEnv *env, SOCKETADDRESS *sa, SOCKETADDRESS *netif, jint timeout,
           jint ttl)
 {
     jint fd;
     int connect_rv = -1;

     // open a TCP socket
     fd = socket(AF_INET, SOCK_STREAM, 0);
     if (fd == -1) {
         // note: if you run out of fds, you may not be able to load
         // the exception class, and get a NoClassDefFoundError instead.
         NET_ThrowNew(env, errno, "Can't create socket");
         return JNI_FALSE;
     }

     // set TTL
     if (ttl > 0) {
         setsockopt(fd, IPPROTO_IP, IP_TTL, &ttl, sizeof(ttl));
     }

     // A network interface was specified, so let's bind to it.
     if (netif != NULL) {
         if (bind(fd, &netif->sa, sizeof(struct sockaddr_in)) < 0) {
             NET_ThrowNew(env, errno, "Can't bind socket");
             close(fd);
             return JNI_FALSE;
         }
     }

     // Make the socket non blocking so we can use select/poll.
     SET_NONBLOCKING(fd);

     sa->sa4.sin_port = htons(7); // echo port
     connect_rv = NET_Connect(fd, &sa->sa, sizeof(struct sockaddr_in));

     // connection established or refused immediately, either way it means
     // we were able to reach the host!
     if (connect_rv == 0 || errno == ECONNREFUSED) {
         close(fd);
         return JNI_TRUE;
     }

     switch (errno) {
     case ENETUNREACH:   // Network Unreachable
     case EAFNOSUPPORT:  // Address Family not supported
     case EADDRNOTAVAIL: // address is not available on the remote machine
 #if defined(__linux__) || defined(_AIX)
         // On some Linux versions, when a socket is bound to the loopback
         // interface, connect will fail and errno will be set to EINVAL
         // or EHOSTUNREACH.  When that happens, don't throw an exception,
         // just return false.
     case EINVAL:
     case EHOSTUNREACH:  // No route to host
 #endif
         close(fd);
         return JNI_FALSE;
     case EINPROGRESS:   // this is expected as we'll probably have to wait
         break;
     default:
         NET_ThrowByNameWithLastError(env, JNU_JAVANETPKG "ConnectException",
                                      "connect failed");
         close(fd);
         return JNI_FALSE;
     }

     timeout = NET_Wait(env, fd, NET_WAIT_CONNECT, timeout);
     if (timeout >= 0) {
         // connection has been established, check for error condition
         socklen_t optlen = (socklen_t)sizeof(connect_rv);
         if (getsockopt(fd, SOL_SOCKET, SO_ERROR, (void*)&connect_rv,
                        &optlen) <0)
         {
             connect_rv = errno;
         }
         if (connect_rv == 0 || connect_rv == ECONNREFUSED) {
             close(fd);
             return JNI_TRUE;
         }
     }
     close(fd);
     return JNI_FALSE;
 }

 /**
  * ping implementation.
  * Send an ICMP_ECHO_REQUEST packet every second until either the timeout
  * expires or an answer is received.
  * Returns true if an ECHO_REPLY is received, false otherwise.
  */
 static jboolean
 ping4(JNIEnv *env, jint fd, SOCKETADDRESS *sa, SOCKETADDRESS *netif,
       jint timeout, jint ttl)
 {
     jint n, size = 60 * 1024, hlen, tmout2, seq = 1;
     socklen_t len;
     unsigned char sendbuf[1500], recvbuf[1500];
     struct icmp *icmp;
     struct ip *ip;
     struct sockaddr_in sa_recv;
     jchar pid;
     struct timeval tv;
     size_t plen = ICMP_ADVLENMIN + sizeof(tv);

     setsockopt(fd, SOL_SOCKET, SO_RCVBUF, &size, sizeof(size));

     // sets the ttl (max number of hops)
     if (ttl > 0) {
         setsockopt(fd, IPPROTO_IP, IP_TTL, &ttl, sizeof(ttl));
     }

     // a specific interface was specified, so let's bind the socket
     // to that interface to ensure the requests are sent only through it.
     if (netif != NULL) {
         if (bind(fd, &netif->sa, sizeof(struct sockaddr_in)) < 0) {
             NET_ThrowNew(env, errno, "Can't bind socket");
             close(fd);
             return JNI_FALSE;
         }
     }

     // icmp_id is a 16 bit data type, therefore down cast the pid
     pid = (jchar)getpid();

     // Make the socket non blocking so we can use select
     SET_NONBLOCKING(fd);
     do {
         // create the ICMP request
         icmp = (struct icmp *)sendbuf;
         icmp->icmp_type = ICMP_ECHO;
         icmp->icmp_code = 0;
         // let's tag the ECHO packet with our pid so we can identify it
         icmp->icmp_id = htons(pid);
         icmp->icmp_seq = htons(seq);
         seq++;
         gettimeofday(&tv, NULL);
         memcpy(icmp->icmp_data, &tv, sizeof(tv));
         icmp->icmp_cksum = 0;
         // manually calculate checksum
         icmp->icmp_cksum = in_cksum((u_short *)icmp, plen);
         // send it
         n = sendto(fd, sendbuf, plen, 0, &sa->sa, sizeof(struct sockaddr_in));
         if (n < 0 && errno != EINPROGRESS) {
 #if defined(__linux__)
             /*
              * On some Linux versions, when a socket is bound to the loopback
              * interface, sendto will fail and errno will be set to
              * EINVAL or EHOSTUNREACH. When that happens, don't throw an
              * exception, just return false.
              */
             if (errno != EINVAL && errno != EHOSTUNREACH) {
                 NET_ThrowNew(env, errno, "Can't send ICMP packet");
             }
 #else
             NET_ThrowNew(env, errno, "Can't send ICMP packet");
 #endif
             close(fd);
             return JNI_FALSE;
         }

         tmout2 = timeout > 1000 ? 1000 : timeout;
         do {
             tmout2 = NET_Wait(env, fd, NET_WAIT_READ, tmout2);
             if (tmout2 >= 0) {
                 len = sizeof(sa_recv);
                 n = recvfrom(fd, recvbuf, sizeof(recvbuf), 0,
                              (struct sockaddr *)&sa_recv, &len);
                 // check if we received enough data
                 if (n < (jint)sizeof(struct ip)) {
                     continue;
                 }
                 ip = (struct ip *)recvbuf;
                 hlen = ((jint)(unsigned int)(ip->ip_hl)) << 2;
                 // check if we received enough data
                 if (n < (jint)(hlen + sizeof(struct icmp))) {
                     continue;
                 }
                 icmp = (struct icmp *)(recvbuf + hlen);
                 // We did receive something, but is it what we were expecting?
                 // I.E.: An ICMP_ECHO_REPLY packet with the proper PID and
                 //       from the host that we are trying to determine is reachable.
                 if (icmp->icmp_type == ICMP_ECHOREPLY &&
                     (ntohs(icmp->icmp_id) == pid))
                 {
                     if (sa->sa4.sin_addr.s_addr == sa_recv.sin_addr.s_addr) {
                         close(fd);
                         return JNI_TRUE;
                     } else if (sa->sa4.sin_addr.s_addr == 0) {
                         close(fd);
                         return JNI_TRUE;
                     }
                 }
             }
         } while (tmout2 > 0);
         timeout -= 1000;
     } while (timeout > 0);
     close(fd);
     return JNI_FALSE;
 }

 /*
  * Class:     java_net_Inet4AddressImpl
  * Method:    isReachable0
  * Signature: ([bI[bI)Z
  */
 JNIEXPORT jboolean JNICALL
 Java_java_net_Inet4AddressImpl_isReachable0(JNIEnv *env, jobject this,
                                             jbyteArray addrArray, jint timeout,
                                             jbyteArray ifArray, jint ttl)
 {
     jbyte caddr[4];
     jint addr = 0, sz, fd;
     SOCKETADDRESS sa, inf, *netif = NULL;

     // check if address array size is 4 (IPv4 address)
     sz = (*env)->GetArrayLength(env, addrArray);
     if (sz != 4) {
       return JNI_FALSE;
     }

     // convert IP address from byte array to integer
     memset((char *)caddr, 0, sizeof(caddr));
     (*env)->GetByteArrayRegion(env, addrArray, 0, 4, caddr);
     addr = ((caddr[0] << 24) & 0xff000000);
     addr |= ((caddr[1] << 16) & 0xff0000);
     addr |= ((caddr[2] << 8) & 0xff00);
     addr |= (caddr[3] & 0xff);
     memset((char *)&sa, 0, sizeof(SOCKETADDRESS));
     sa.sa4.sin_addr.s_addr = htonl(addr);
     sa.sa4.sin_family = AF_INET;

     // If a network interface was specified, let's convert its address as well.
     if (!(IS_NULL(ifArray))) {
         memset((char *)caddr, 0, sizeof(caddr));
         (*env)->GetByteArrayRegion(env, ifArray, 0, 4, caddr);
         addr = ((caddr[0] << 24) & 0xff000000);
         addr |= ((caddr[1] << 16) & 0xff0000);
         addr |= ((caddr[2] << 8) & 0xff00);
         addr |= (caddr[3] & 0xff);
         memset((char *)&inf, 0, sizeof(SOCKETADDRESS));
         inf.sa4.sin_addr.s_addr = htonl(addr);
         inf.sa4.sin_family = AF_INET;
         netif = &inf;
     }

     // Let's try to create a RAW socket to send ICMP packets.
     // This usually requires "root" privileges, so it's likely to fail.
     fd = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP);
     if (fd == -1) {
         return tcp_ping4(env, &sa, netif, timeout, ttl);
     } else {
         // It didn't fail, so we can use ICMP_ECHO requests.
         return ping4(env, fd, &sa, netif, timeout, ttl);
     }
 }
	/*
	* Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code 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 General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/
	#include <ctype.h>
	#include <errno.h>
	#include <sys/types.h>
	#include <netinet/in.h>
	#include <netinet/in_systm.h>
	#include <netinet/ip.h>
	#include <netinet/ip_icmp.h>
	#include <stdlib.h>
	#include <string.h>
	#include <sys/time.h>

	#include "net_util.h"

	#include "java_net_Inet4AddressImpl.h"

	#if defined(MACOSX)
	extern jobjectArray lookupIfLocalhost(JNIEnv env, const char hostname, jboolean includeV6);
	#endif

	#define SET_NONBLOCKING(fd) { \
	int flags = fcntl(fd, F_GETFL); \
	flags \|= O_NONBLOCK; \
	fcntl(fd, F_SETFL, flags); \
	}

	/*
	* Inet4AddressImpl
	*/

	/*
	* Class: java_net_Inet4AddressImpl
	* Method: getLocalHostName
	* Signature: ()Ljava/lang/String;
	*/
	JNIEXPORT jstring JNICALL
	Java_java_net_Inet4AddressImpl_getLocalHostName(JNIEnv *env, jobject this) {
	char hostname[NI_MAXHOST + 1];

	hostname[0] = '\0';
	if (gethostname(hostname, sizeof(hostname)) != 0) {
	strcpy(hostname, "localhost");
	} else {
	#if defined(__solaris__)
	// try to resolve hostname via nameservice
	// if it is known but getnameinfo fails, hostname will still be the
	// value from gethostname
	struct addrinfo hints, *res;

	// make sure string is null-terminated
	hostname[NI_MAXHOST] = '\0';
	memset(&hints, 0, sizeof(hints));
	hints.ai_flags = AI_CANONNAME;
	hints.ai_family = AF_INET;

	if (getaddrinfo(hostname, NULL, &hints, &res) == 0) {
	getnameinfo(res->ai_addr, res->ai_addrlen, hostname, sizeof(hostname),
	NULL, 0, NI_NAMEREQD);
	freeaddrinfo(res);
	}
	#else
	// make sure string is null-terminated
	hostname[NI_MAXHOST] = '\0';
	#endif
	}
	return (*env)->NewStringUTF(env, hostname);
	}

	/*
	* Find an internet address for a given hostname. Note that this
	* code only works for addresses of type INET. The translation
	* of %d.%d.%d.%d to an address (int) occurs in java now, so the
	* String "host" shouldn't be a %d.%d.%d.%d string. The only
	* exception should be when any of the %d are out of range and
	* we fallback to a lookup.
	*
	* Class: java_net_Inet4AddressImpl
	* Method: lookupAllHostAddr
	* Signature: (Ljava/lang/String;)[[B
	*/
	JNIEXPORT jobjectArray JNICALL
	Java_java_net_Inet4AddressImpl_lookupAllHostAddr(JNIEnv *env, jobject this,
	jstring host) {
	jobjectArray ret = NULL;
	const char *hostname;
	int error = 0;
	struct addrinfo hints, res = NULL, resNew = NULL, *last = NULL,
	*iterator;

	initInetAddressIDs(env);
	JNU_CHECK_EXCEPTION_RETURN(env, NULL);

	if (IS_NULL(host)) {
	JNU_ThrowNullPointerException(env, "host argument is null");
	return NULL;
	}
	hostname = JNU_GetStringPlatformChars(env, host, JNI_FALSE);
	CHECK_NULL_RETURN(hostname, NULL);

	// try once, with our static buffer
	memset(&hints, 0, sizeof(hints));
	hints.ai_flags = AI_CANONNAME;
	hints.ai_family = AF_INET;

	error = getaddrinfo(hostname, NULL, &hints, &res);

	if (error) {
	#if defined(MACOSX)
	// If getaddrinfo fails try getifaddrs, see bug 8170910.
	ret = lookupIfLocalhost(env, hostname, JNI_FALSE);
	if (ret != NULL \|\| (*env)->ExceptionCheck(env)) {
	goto cleanupAndReturn;
	}
	#endif
	// report error
	NET_ThrowUnknownHostExceptionWithGaiError(env, hostname, error);
	goto cleanupAndReturn;
	} else {
	int i = 0;
	iterator = res;
	while (iterator != NULL) {
	// skip duplicates
	int skip = 0;
	struct addrinfo *iteratorNew = resNew;
	while (iteratorNew != NULL) {
	struct sockaddr_in addr1, addr2;
	addr1 = (struct sockaddr_in *)iterator->ai_addr;
	addr2 = (struct sockaddr_in *)iteratorNew->ai_addr;
	if (addr1->sin_addr.s_addr == addr2->sin_addr.s_addr) {
	skip = 1;
	break;
	}
	iteratorNew = iteratorNew->ai_next;
	}

	if (!skip) {
	struct addrinfo *next
	= (struct addrinfo *)malloc(sizeof(struct addrinfo));
	if (!next) {
	JNU_ThrowOutOfMemoryError(env, "Native heap allocation failed");
	ret = NULL;
	goto cleanupAndReturn;
	}
	memcpy(next, iterator, sizeof(struct addrinfo));
	next->ai_next = NULL;
	if (resNew == NULL) {
	resNew = next;
	} else {
	last->ai_next = next;
	}
	last = next;
	i++;
	}
	iterator = iterator->ai_next;
	}

	// allocate array - at this point i contains the number of addresses
	ret = (*env)->NewObjectArray(env, i, ia_class, NULL);
	if (IS_NULL(ret)) {
	goto cleanupAndReturn;
	}

	i = 0;
	iterator = resNew;
	while (iterator != NULL) {
	jobject iaObj = (*env)->NewObject(env, ia4_class, ia4_ctrID);
	if (IS_NULL(iaObj)) {
	ret = NULL;
	goto cleanupAndReturn;
	}
	setInetAddress_addr(env, iaObj, ntohl(((struct sockaddr_in *)
	(iterator->ai_addr))->sin_addr.s_addr));
	if ((*env)->ExceptionCheck(env))
	goto cleanupAndReturn;
	setInetAddress_hostName(env, iaObj, host);
	if ((*env)->ExceptionCheck(env))
	goto cleanupAndReturn;
	(*env)->SetObjectArrayElement(env, ret, i++, iaObj);
	iterator = iterator->ai_next;
	}
	}
	cleanupAndReturn:
	JNU_ReleaseStringPlatformChars(env, host, hostname);
	while (resNew != NULL) {
	last = resNew;
	resNew = resNew->ai_next;
	free(last);
	}
	if (res != NULL) {
	freeaddrinfo(res);
	}
	return ret;
	}

	/*
	* Class: java_net_Inet4AddressImpl
	* Method: getHostByAddr
	* Signature: (I)Ljava/lang/String;
	*
	* Theoretically the UnknownHostException could be enriched with gai error
	* information. But as it is silently ignored anyway, there's no need for this.
	* It's only important that either a valid hostname is returned or an
	* UnknownHostException is thrown.
	*/
	JNIEXPORT jstring JNICALL
	Java_java_net_Inet4AddressImpl_getHostByAddr(JNIEnv *env, jobject this,
	jbyteArray addrArray) {
	jstring ret = NULL;
	char host[NI_MAXHOST + 1];
	jbyte caddr[4];
	jint addr;
	struct sockaddr_in sa;

	// construct a sockaddr_in structure
	memset((char *)&sa, 0, sizeof(struct sockaddr_in));
	(*env)->GetByteArrayRegion(env, addrArray, 0, 4, caddr);
	addr = ((caddr[0] << 24) & 0xff000000);
	addr \|= ((caddr[1] << 16) & 0xff0000);
	addr \|= ((caddr[2] << 8) & 0xff00);
	addr \|= (caddr[3] & 0xff);
	sa.sin_addr.s_addr = htonl(addr);
	sa.sin_family = AF_INET;

	if (getnameinfo((struct sockaddr *)&sa, sizeof(struct sockaddr_in),
	host, sizeof(host), NULL, 0, NI_NAMEREQD)) {
	JNU_ThrowByName(env, "java/net/UnknownHostException", NULL);
	} else {
	ret = (*env)->NewStringUTF(env, host);
	if (ret == NULL) {
	JNU_ThrowByName(env, "java/net/UnknownHostException", NULL);
	}
	}

	return ret;
	}

	/**
	* ping implementation using tcp port 7 (echo)
	*/
	static jboolean
	tcp_ping4(JNIEnv env, SOCKETADDRESS sa, SOCKETADDRESS *netif, jint timeout,
	jint ttl)
	{
	jint fd;
	int connect_rv = -1;

	// open a TCP socket
	fd = socket(AF_INET, SOCK_STREAM, 0);
	if (fd == -1) {
	// note: if you run out of fds, you may not be able to load
	// the exception class, and get a NoClassDefFoundError instead.
	NET_ThrowNew(env, errno, "Can't create socket");
	return JNI_FALSE;
	}

	// set TTL
	if (ttl > 0) {
	setsockopt(fd, IPPROTO_IP, IP_TTL, &ttl, sizeof(ttl));
	}

	// A network interface was specified, so let's bind to it.
	if (netif != NULL) {
	if (bind(fd, &netif->sa, sizeof(struct sockaddr_in)) < 0) {
	NET_ThrowNew(env, errno, "Can't bind socket");
	close(fd);
	return JNI_FALSE;
	}
	}

	// Make the socket non blocking so we can use select/poll.
	SET_NONBLOCKING(fd);

	sa->sa4.sin_port = htons(7); // echo port
	connect_rv = NET_Connect(fd, &sa->sa, sizeof(struct sockaddr_in));

	// connection established or refused immediately, either way it means
	// we were able to reach the host!
	if (connect_rv == 0 \|\| errno == ECONNREFUSED) {
	close(fd);
	return JNI_TRUE;
	}

	switch (errno) {
	case ENETUNREACH: // Network Unreachable
	case EAFNOSUPPORT: // Address Family not supported
	case EADDRNOTAVAIL: // address is not available on the remote machine
	#if defined(__linux__) \|\| defined(_AIX)
	// On some Linux versions, when a socket is bound to the loopback
	// interface, connect will fail and errno will be set to EINVAL
	// or EHOSTUNREACH. When that happens, don't throw an exception,
	// just return false.
	case EINVAL:
	case EHOSTUNREACH: // No route to host
	#endif
	close(fd);
	return JNI_FALSE;
	case EINPROGRESS: // this is expected as we'll probably have to wait
	break;
	default:
	NET_ThrowByNameWithLastError(env, JNU_JAVANETPKG "ConnectException",
	"connect failed");
	close(fd);
	return JNI_FALSE;
	}

	timeout = NET_Wait(env, fd, NET_WAIT_CONNECT, timeout);
	if (timeout >= 0) {
	// connection has been established, check for error condition
	socklen_t optlen = (socklen_t)sizeof(connect_rv);
	if (getsockopt(fd, SOL_SOCKET, SO_ERROR, (void*)&connect_rv,
	&optlen) <0)
	{
	connect_rv = errno;
	}
	if (connect_rv == 0 \|\| connect_rv == ECONNREFUSED) {
	close(fd);
	return JNI_TRUE;
	}
	}
	close(fd);
	return JNI_FALSE;
	}

	/**
	* ping implementation.
	* Send an ICMP_ECHO_REQUEST packet every second until either the timeout
	* expires or an answer is received.
	* Returns true if an ECHO_REPLY is received, false otherwise.
	*/
	static jboolean
	ping4(JNIEnv env, jint fd, SOCKETADDRESS sa, SOCKETADDRESS *netif,
	jint timeout, jint ttl)
	{
	jint n, size = 60 * 1024, hlen, tmout2, seq = 1;
	socklen_t len;
	unsigned char sendbuf[1500], recvbuf[1500];
	struct icmp *icmp;
	struct ip *ip;
	struct sockaddr_in sa_recv;
	jchar pid;
	struct timeval tv;
	size_t plen = ICMP_ADVLENMIN + sizeof(tv);

	setsockopt(fd, SOL_SOCKET, SO_RCVBUF, &size, sizeof(size));

	// sets the ttl (max number of hops)
	if (ttl > 0) {
	setsockopt(fd, IPPROTO_IP, IP_TTL, &ttl, sizeof(ttl));
	}

	// a specific interface was specified, so let's bind the socket
	// to that interface to ensure the requests are sent only through it.
	if (netif != NULL) {
	if (bind(fd, &netif->sa, sizeof(struct sockaddr_in)) < 0) {
	NET_ThrowNew(env, errno, "Can't bind socket");
	close(fd);
	return JNI_FALSE;
	}
	}

	// icmp_id is a 16 bit data type, therefore down cast the pid
	pid = (jchar)getpid();

	// Make the socket non blocking so we can use select
	SET_NONBLOCKING(fd);
	do {
	// create the ICMP request
	icmp = (struct icmp *)sendbuf;
	icmp->icmp_type = ICMP_ECHO;
	icmp->icmp_code = 0;
	// let's tag the ECHO packet with our pid so we can identify it
	icmp->icmp_id = htons(pid);
	icmp->icmp_seq = htons(seq);
	seq++;
	gettimeofday(&tv, NULL);
	memcpy(icmp->icmp_data, &tv, sizeof(tv));
	icmp->icmp_cksum = 0;
	// manually calculate checksum
	icmp->icmp_cksum = in_cksum((u_short *)icmp, plen);
	// send it
	n = sendto(fd, sendbuf, plen, 0, &sa->sa, sizeof(struct sockaddr_in));
	if (n < 0 && errno != EINPROGRESS) {
	#if defined(__linux__)
	/*
	* On some Linux versions, when a socket is bound to the loopback
	* interface, sendto will fail and errno will be set to
	* EINVAL or EHOSTUNREACH. When that happens, don't throw an
	* exception, just return false.
	*/
	if (errno != EINVAL && errno != EHOSTUNREACH) {
	NET_ThrowNew(env, errno, "Can't send ICMP packet");
	}
	#else
	NET_ThrowNew(env, errno, "Can't send ICMP packet");
	#endif
	close(fd);
	return JNI_FALSE;
	}

	tmout2 = timeout > 1000 ? 1000 : timeout;
	do {
	tmout2 = NET_Wait(env, fd, NET_WAIT_READ, tmout2);
	if (tmout2 >= 0) {
	len = sizeof(sa_recv);
	n = recvfrom(fd, recvbuf, sizeof(recvbuf), 0,
	(struct sockaddr *)&sa_recv, &len);
	// check if we received enough data
	if (n < (jint)sizeof(struct ip)) {
	continue;
	}
	ip = (struct ip *)recvbuf;
	hlen = ((jint)(unsigned int)(ip->ip_hl)) << 2;
	// check if we received enough data
	if (n < (jint)(hlen + sizeof(struct icmp))) {
	continue;
	}
	icmp = (struct icmp *)(recvbuf + hlen);
	// We did receive something, but is it what we were expecting?
	// I.E.: An ICMP_ECHO_REPLY packet with the proper PID and
	// from the host that we are trying to determine is reachable.
	if (icmp->icmp_type == ICMP_ECHOREPLY &&
	(ntohs(icmp->icmp_id) == pid))
	{
	if (sa->sa4.sin_addr.s_addr == sa_recv.sin_addr.s_addr) {
	close(fd);
	return JNI_TRUE;
	} else if (sa->sa4.sin_addr.s_addr == 0) {
	close(fd);
	return JNI_TRUE;
	}
	}
	}
	} while (tmout2 > 0);
	timeout -= 1000;
	} while (timeout > 0);
	close(fd);
	return JNI_FALSE;
	}

	/*
	* Class: java_net_Inet4AddressImpl
	* Method: isReachable0
	* Signature: ([bI[bI)Z
	*/
	JNIEXPORT jboolean JNICALL
	Java_java_net_Inet4AddressImpl_isReachable0(JNIEnv *env, jobject this,
	jbyteArray addrArray, jint timeout,
	jbyteArray ifArray, jint ttl)
	{
	jbyte caddr[4];
	jint addr = 0, sz, fd;
	SOCKETADDRESS sa, inf, *netif = NULL;

	// check if address array size is 4 (IPv4 address)
	sz = (*env)->GetArrayLength(env, addrArray);
	if (sz != 4) {
	return JNI_FALSE;
	}

	// convert IP address from byte array to integer
	memset((char *)caddr, 0, sizeof(caddr));
	(*env)->GetByteArrayRegion(env, addrArray, 0, 4, caddr);
	addr = ((caddr[0] << 24) & 0xff000000);
	addr \|= ((caddr[1] << 16) & 0xff0000);
	addr \|= ((caddr[2] << 8) & 0xff00);
	addr \|= (caddr[3] & 0xff);
	memset((char *)&sa, 0, sizeof(SOCKETADDRESS));
	sa.sa4.sin_addr.s_addr = htonl(addr);
	sa.sa4.sin_family = AF_INET;

	// If a network interface was specified, let's convert its address as well.
	if (!(IS_NULL(ifArray))) {
	memset((char *)caddr, 0, sizeof(caddr));
	(*env)->GetByteArrayRegion(env, ifArray, 0, 4, caddr);
	addr = ((caddr[0] << 24) & 0xff000000);
	addr \|= ((caddr[1] << 16) & 0xff0000);
	addr \|= ((caddr[2] << 8) & 0xff00);
	addr \|= (caddr[3] & 0xff);
	memset((char *)&inf, 0, sizeof(SOCKETADDRESS));
	inf.sa4.sin_addr.s_addr = htonl(addr);
	inf.sa4.sin_family = AF_INET;
	netif = &inf;
	}

	// Let's try to create a RAW socket to send ICMP packets.
	// This usually requires "root" privileges, so it's likely to fail.
	fd = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP);
	if (fd == -1) {
	return tcp_ping4(env, &sa, netif, timeout, ttl);
	} else {
	// It didn't fail, so we can use ICMP_ECHO requests.
	return ping4(env, fd, &sa, netif, timeout, ttl);
	}
	}