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Java example source code file (NetworkInterface_winXP.c)

This example Java source code file (NetworkInterface_winXP.c) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

dword, error_success, getadaptersaddresses, ip_adapter_addresses, jni_false, jni_true, jnicall, jnienv, jniexport, jnu_throwbyname, native, null, pwchar, ulong

The NetworkInterface_winXP.c Java example source code

/*
 * Copyright (c) 2003, 2013, 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 <stdlib.h>
#include <windows.h>
#include <winsock2.h>           /* needed for htonl */
#include <iprtrmib.h>
#include <assert.h>

#include "java_net_NetworkInterface.h"
#include "jni_util.h"

#include "NetworkInterface.h"
#include "net_util.h"

/*
 * Windows implementation of the java.net.NetworkInterface native methods.
 * This module provides the implementations of getAll, getByName, getByIndex,
 * and getByAddress.
 */

extern int enumAddresses_win(JNIEnv *env, netif *netifP, netaddr **netaddrPP);
int getAddrsFromAdapter(IP_ADAPTER_ADDRESSES *ptr, netaddr **netaddrPP);

#ifdef DEBUG
void printnif (netif *nif) {
#ifdef _WIN64
        printf ("nif:0x%I64x name:%s\n", nif,nif->name);
#else
        printf ("nif:0x%x name:%s\n", nif,nif->name);
#endif
        if (nif->dNameIsUnicode) {
            printf ("dName:%S index:%d ", nif->displayName,nif->index);
        } else {
            printf ("dName:%s index:%d ", nif->displayName,nif->index);
        }
        printf ("naddrs:%d\n", nif->naddrs);
}

void printnifs (netif *netifPP, char *str) {
    netif *nif;
    printf ("%s\n", str);
    for (nif=netifPP; nif!=NULL; nif=nif->next) {
        printnif (nif);
    }
    printf("-----------------\n");
}

#endif

static int bufsize = 1024;

/*
 * return an array of IP_ADAPTER_ADDRESSES containing one element
 * for each adapter on the system. Returned in *adapters.
 * Buffer is malloc'd and must be freed (unless error returned)
 */
static int getAdapters (JNIEnv *env, IP_ADAPTER_ADDRESSES **adapters) {
    DWORD ret, flags;
    IP_ADAPTER_ADDRESSES *adapterInfo;
    ULONG len;
    adapterInfo = (IP_ADAPTER_ADDRESSES *)malloc (bufsize);
    if (adapterInfo == NULL) {
        JNU_ThrowByName(env, "java/lang/OutOfMemoryError", "Native heap allocation failure");
        return -1;
    }

    len = bufsize;
    flags = GAA_FLAG_SKIP_DNS_SERVER;
    flags |= GAA_FLAG_SKIP_MULTICAST;
    flags |= GAA_FLAG_INCLUDE_PREFIX;
    ret = GetAdaptersAddresses(AF_UNSPEC, flags, NULL, adapterInfo, &len);

    if (ret == ERROR_BUFFER_OVERFLOW) {
        IP_ADAPTER_ADDRESSES * newAdapterInfo = (IP_ADAPTER_ADDRESSES *) realloc (adapterInfo, len);
        if (newAdapterInfo == NULL) {
            free(adapterInfo);
            JNU_ThrowByName(env, "java/lang/OutOfMemoryError", "Native heap allocation failure");
            return -1;
        }

        adapterInfo = newAdapterInfo;

        bufsize = len;
        ret = GetAdaptersAddresses(AF_UNSPEC, flags, NULL, adapterInfo, &len);
    }

    if (ret != ERROR_SUCCESS) {
        free (adapterInfo);
        JNU_ThrowByName(env, "java/lang/Error",
                "IP Helper Library GetAdaptersAddresses function failed");
        return -1;
    }
    *adapters = adapterInfo;
    return ERROR_SUCCESS;
}

/*
 * return an array of IP_ADAPTER_ADDRESSES containing one element
 * for each adapter on the system. Returned in *adapters.
 * Buffer is malloc'd and must be freed (unless error returned)
 */
IP_ADAPTER_ADDRESSES *getAdapter (JNIEnv *env,  jint index) {
    DWORD flags, val;
    IP_ADAPTER_ADDRESSES *adapterInfo, *ptr, *ret;
    ULONG len;
    adapterInfo = (IP_ADAPTER_ADDRESSES *)malloc (bufsize);
    if (adapterInfo == NULL) {
        JNU_ThrowByName(env, "java/lang/OutOfMemoryError", "Native heap allocation failure");
        return NULL;
    }
    len = bufsize;
    flags = GAA_FLAG_SKIP_DNS_SERVER;
    flags |= GAA_FLAG_SKIP_MULTICAST;
    flags |= GAA_FLAG_INCLUDE_PREFIX;
    val = GetAdaptersAddresses(AF_UNSPEC, flags, NULL, adapterInfo, &len);
    if (val == ERROR_BUFFER_OVERFLOW) {
        IP_ADAPTER_ADDRESSES * newAdapterInfo = (IP_ADAPTER_ADDRESSES *) realloc (adapterInfo, len);
        if (newAdapterInfo == NULL) {
            free(adapterInfo);
            JNU_ThrowByName(env, "java/lang/OutOfMemoryError", "Native heap allocation failure");
            return NULL;
        }

        adapterInfo = newAdapterInfo;

        bufsize = len;
        val = GetAdaptersAddresses(AF_UNSPEC, flags, NULL, adapterInfo, &len);
    }

    if (val != ERROR_SUCCESS) {
        free (adapterInfo);
        JNU_ThrowByName(env, "java/lang/Error",
                "IP Helper Library GetAdaptersAddresses function failed");
        return NULL;
    }
    ptr = adapterInfo;
    ret = NULL;
    while (ptr != NULL) {
      // in theory the IPv4 index and the IPv6 index can be the same
      // where an interface is enabled for v4 and v6
      // IfIndex == 0 IPv4 not available on this interface
      // Ipv6IfIndex == 0 IPv6 not available on this interface
      if (((ptr->IfIndex != 0)&&(ptr->IfIndex == index)) ||
          ((ptr->Ipv6IfIndex !=0) && (ptr->Ipv6IfIndex == index))) {
        ret = (IP_ADAPTER_ADDRESSES *) malloc(sizeof(IP_ADAPTER_ADDRESSES));
        if (ret == NULL) {
            free(adapterInfo);
            JNU_ThrowByName(env, "java/lang/OutOfMemoryError", "Native heap allocation failure");
            return NULL;
        }

        //copy the memory and break out of the while loop.
        memcpy(ret, ptr, sizeof(IP_ADAPTER_ADDRESSES));
        break;

      }
      ptr=ptr->Next;
    }
    free(adapterInfo);
    return ret;
}

static int ipinflen = 2048;

/*
 */
int getAllInterfacesAndAddresses (JNIEnv *env, netif **netifPP)
{
    DWORD ret;
    IP_ADAPTER_ADDRESSES *ptr, *adapters=NULL;
    ULONG len=ipinflen, count=0;
    netif *nif=NULL, *dup_nif, *last=NULL, *loopif=NULL, *curr;
    int tun=0, net=0;

    *netifPP = NULL;
   /*
    * Get the IPv4 interfaces. This information is the same
    * as what previous JDK versions would return.
    */

    ret = enumInterfaces(env, netifPP);
    if (ret == -1) {
        return -1;
    } else {
        count = ret;
    }

    /* locate the loopback (and the last) interface */
    for (nif=*netifPP, last=nif; nif!=NULL; nif=nif->next) {
        if (nif->ifType == MIB_IF_TYPE_LOOPBACK) {
            loopif = nif;
        }
        last = nif;
    }

    // Retrieve IPv4 addresses with the IP Helper API
    curr = *netifPP;
    while (curr != NULL) {
        netaddr *netaddrP;
        ret = enumAddresses_win(env, curr, &netaddrP);
        if (ret == -1) {
            return -1;
        }
        curr->addrs = netaddrP;
        curr->naddrs += ret;
        curr = curr->next;
    }

    ret = getAdapters (env, &adapters);
    if (ret != ERROR_SUCCESS) {
        goto err;
    }

    /* Now get the IPv6 information. This includes:
     *  (a)  IPv6 information associated with interfaces already found
     *  (b)  IPv6 information for IPv6 only interfaces (probably tunnels)
     *
     * For compatibility with previous releases we use the naming
     * information gotten from enumInterfaces() for (a) entries
     * However, the index numbers are taken from the new API.
     *
     * The procedure is to go through the list of adapters returned
     * by the new API looking for entries that correspond to IPv4 interfaces
     * already found.
     */

    ptr = adapters;
    while (ptr != NULL) {
        int c;
        netif *nif0;
        if (ptr->IfType == IF_TYPE_SOFTWARE_LOOPBACK && (loopif != NULL)) {
            c = getAddrsFromAdapter(ptr, &loopif->addrs);
            if (c == -1) {
                goto err;
            }
            loopif->naddrs += c;
        } else {
            int index = ptr->IfIndex;
            if (index != 0) {
                /* This entry is associated with an IPv4 interface */
                for (nif=*netifPP; nif!=NULL; nif=nif->next) {
                    if (nif->index == index) {
                        /* found the interface entry
                         * set the index to the IPv6 index and add the
                         * IPv6 addresses
                         */
                        nif->ipv6Index = ptr->Ipv6IfIndex;
                        c = getAddrsFromAdapter(ptr, &nif->addrs);
                        nif->naddrs += c;
                        break;
                    }
                }
            } else {
                /* This entry is IPv6 only */
                char newname [128];
                int c;

                /* Windows allocates duplicate adapter entries
                 * for tunnel interfaces when there are multiple
                 * physical adapters. Need to check
                 * if this is a duplicate (ipv6Index is the same)
                 */
                dup_nif = 0;
                for (nif0=*netifPP; nif0!=NULL; nif0=nif0->next) {
                    if (nif0->hasIpv6Address &&
                                ptr->Ipv6IfIndex == nif0->ipv6Index) {
                        dup_nif = nif0;
                        break;
                    }
                }
                if (dup_nif == 0) {
                    /* new interface */
                        nif = (netif *) calloc (1, sizeof(netif));
                        if (nif == 0) {
                            goto err;
                        }
                        if (ptr->IfType == IF_TYPE_TUNNEL) {
                                sprintf (newname, "tun%d", tun);
                                tun ++;
                        } else {
                                sprintf (newname, "net%d", net);
                                net ++;
                        }
                        nif->name = malloc (strlen(newname)+1);
                        nif->displayName = malloc (wcslen(ptr->FriendlyName)*2+2);
                        if (nif->name == 0 || nif->displayName == 0) {
                                goto err;
                        }
                        strcpy (nif->name, newname);
                        wcscpy ((PWCHAR)nif->displayName, ptr->FriendlyName);
                        nif->dNameIsUnicode = TRUE;

                        // the java.net.NetworkInterface abstraction only has index
                        // so the Ipv6IfIndex needs to map onto index
                        nif->index = ptr->Ipv6IfIndex;
                        nif->ipv6Index = ptr->Ipv6IfIndex;
                        nif->hasIpv6Address = TRUE;

                        last->next = nif;
                        last = nif;
                        count++;
                        c = getAddrsFromAdapter(ptr, &nif->addrs);
                        if (c == -1) {
                                goto err;
                        }
                        nif->naddrs += c;
                 } else {
                        /* add the addresses from this adapter to the
                         * original (dup_nif)
                         */
                        c = getAddrsFromAdapter(ptr, &dup_nif->addrs);
                        if (c == -1) {
                                goto err;
                        }
                        dup_nif->naddrs += c;
                }
            }
        }
        ptr=ptr->Next;
    }

    free (adapters);
    return count;

err:
    if (*netifPP) {
        free_netif (*netifPP);
    }
    if (adapters) {
        free (adapters);
    }
    return -1;
}

/* If *netaddrPP is null, then the addresses are allocated and the beginning
 * of the allocated chain is returned in *netaddrPP.
 * If *netaddrPP is not null, then the addresses allocated here are appended
 * to the existing chain.
 *
 * Returns count of addresses or -1 on error.
 */

static int getAddrsFromAdapter(IP_ADAPTER_ADDRESSES *ptr, netaddr **netaddrPP) {
        LPSOCKADDR sock;
        int        count = 0;
        netaddr    *curr, *start = NULL, *prev = NULL;
        PIP_ADAPTER_UNICAST_ADDRESS uni_addr;
        PIP_ADAPTER_ANYCAST_ADDRESS any_addr;
        PIP_ADAPTER_PREFIX prefix;

        /* If chain passed in, find end */
        if (*netaddrPP != NULL) {
            for (start=*netaddrPP; start->next!=NULL; start=start->next)
                ;

            prev=start;
        }

        prefix = ptr->FirstPrefix;
        /* Unicast */
        uni_addr = ptr->FirstUnicastAddress;
        while (uni_addr != NULL) {
        /* address is only usable if dad state is preferred or deprecated */
                if (uni_addr->DadState == IpDadStateDeprecated ||
                                uni_addr->DadState == IpDadStatePreferred) {
                        sock = uni_addr->Address.lpSockaddr;

                        // IPv4 addresses already retrieved with enumAddresses_win
                        if (sock->sa_family == AF_INET) {
                                uni_addr = uni_addr->Next;
                                continue;
                        }

            curr = (netaddr *)calloc (1, sizeof (netaddr));

            if (curr == NULL)
                goto freeAllocatedMemory;

            if (start == NULL)
                start = curr;

            if (prev != NULL)
               prev->next = curr;

            prev = curr;
            SOCKETADDRESS_COPY (&curr->addr, sock);
            if (prefix != NULL) {
              curr->mask = (short)prefix->PrefixLength;
              prefix = prefix->Next;
            }
            count ++;
        }
        uni_addr = uni_addr->Next;
    }
    /* Anycast */
    any_addr = ptr->FirstAnycastAddress;
    while (any_addr != NULL) {
        curr = (netaddr *)calloc (1, sizeof (netaddr));

        if (curr == NULL)
            goto freeAllocatedMemory;

        if (start == NULL)
            start = curr;

        if (prev != NULL)
            prev->next = curr;

        prev = curr;
        sock = any_addr->Address.lpSockaddr;
        SOCKETADDRESS_COPY (&curr->addr, sock);
        count ++;
        any_addr = any_addr->Next;
    }
    if (*netaddrPP == NULL) {
        *netaddrPP = start;
    }
    return count;

freeAllocatedMemory:

    if (*netaddrPP != NULL) {
        //N.B. the variable "start" cannot be NULL at this point because we started with an
        //existing list.
        curr=start->next;
        start->next = NULL;
        start = curr;
    }
    // otherwise, "start" points to the beginning of an incomplete list that we must deallocate.

    while (start != NULL) {
        curr = start->next;
        free(start);
        start = curr;
    }

    return -1;
}

/*
 * Create a NetworkInterface object, populate the name and index, and
 * populate the InetAddress array based on the IP addresses for this
 * interface.
 */
static jobject createNetworkInterfaceXP(JNIEnv *env, netif *ifs)
{
    jobject netifObj;
    jobject name, displayName;
    jobjectArray addrArr, bindsArr, childArr;
    netaddr *addrs;
    jint addr_index;
    int netaddrCount=ifs->naddrs;
    netaddr *netaddrP=ifs->addrs;
    jint bind_index;

    /*
     * Create a NetworkInterface object and populate it
     */
    netifObj = (*env)->NewObject(env, ni_class, ni_ctor);
    name = (*env)->NewStringUTF(env, ifs->name);
    if (ifs->dNameIsUnicode) {
        displayName = (*env)->NewString(env, (PWCHAR)ifs->displayName,
                                        (jsize)wcslen ((PWCHAR)ifs->displayName));
    } else {
        displayName = (*env)->NewStringUTF(env, ifs->displayName);
    }
    if (netifObj == NULL || name == NULL || displayName == NULL) {
        return NULL;
    }
    (*env)->SetObjectField(env, netifObj, ni_nameID, name);
    (*env)->SetObjectField(env, netifObj, ni_displayNameID, displayName);
    (*env)->SetIntField(env, netifObj, ni_indexID, ifs->index);
    /*
     * Get the IP addresses for this interface if necessary
     * Note that 0 is a valid number of addresses.
     */
    if (netaddrCount < 0) {
        netaddrCount = enumAddresses_win(env, ifs, &netaddrP);
        if (netaddrCount == -1) {
            return NULL;
        }
    }

    addrArr = (*env)->NewObjectArray(env, netaddrCount, ni_iacls, NULL);
    if (addrArr == NULL) {
        return NULL;
    }

    bindsArr = (*env)->NewObjectArray(env, netaddrCount, ni_ibcls, NULL);
    if (bindsArr == NULL) {
      free_netaddr(netaddrP);
      return NULL;
    }

    addrs = netaddrP;
    addr_index = 0;
    bind_index = 0;
    while (addrs != NULL) {
        jobject iaObj, ia2Obj;
        jobject ibObj = NULL;
        if (addrs->addr.him.sa_family == AF_INET) {
            iaObj = (*env)->NewObject(env, ni_ia4cls, ni_ia4Ctor);
            if (iaObj == NULL) {
                return NULL;
            }
            /* default ctor will set family to AF_INET */

            setInetAddress_addr(env, iaObj, ntohl(addrs->addr.him4.sin_addr.s_addr));

            ibObj = (*env)->NewObject(env, ni_ibcls, ni_ibctrID);
            if (ibObj == NULL) {
              free_netaddr(netaddrP);
              return NULL;
            }
            (*env)->SetObjectField(env, ibObj, ni_ibaddressID, iaObj);
            ia2Obj = (*env)->NewObject(env, ni_ia4cls, ni_ia4Ctor);
            if (ia2Obj == NULL) {
              free_netaddr(netaddrP);
              return NULL;
            }
            setInetAddress_addr(env, ia2Obj, ntohl(addrs->brdcast.him4.sin_addr.s_addr));
            (*env)->SetObjectField(env, ibObj, ni_ibbroadcastID, ia2Obj);
            (*env)->SetShortField(env, ibObj, ni_ibmaskID, addrs->mask);
            (*env)->SetObjectArrayElement(env, bindsArr, bind_index++, ibObj);
        } else /* AF_INET6 */ {
            int scope;
            iaObj = (*env)->NewObject(env, ni_ia6cls, ni_ia6ctrID);
            if (iaObj) {
                int ret = setInet6Address_ipaddress(env, iaObj, (jbyte *)&(addrs->addr.him6.sin6_addr.s6_addr));
                if (ret == JNI_FALSE) {
                    return NULL;
                }
                scope = addrs->addr.him6.sin6_scope_id;
                if (scope != 0) { /* zero is default value, no need to set */
                    setInet6Address_scopeid(env, iaObj, scope);
                    setInet6Address_scopeifname(env, iaObj, netifObj);
                }
                ibObj = (*env)->NewObject(env, ni_ibcls, ni_ibctrID);
                if (ibObj == NULL) {
                  free_netaddr(netaddrP);
                  return NULL;
                }
                (*env)->SetObjectField(env, ibObj, ni_ibaddressID, iaObj);
                (*env)->SetShortField(env, ibObj, ni_ibmaskID, addrs->mask);
                (*env)->SetObjectArrayElement(env, bindsArr, bind_index++, ibObj);
            }
        }
        (*env)->SetObjectArrayElement(env, addrArr, addr_index, iaObj);
        addrs = addrs->next;
        addr_index++;
    }
    (*env)->SetObjectField(env, netifObj, ni_addrsID, addrArr);
    (*env)->SetObjectField(env, netifObj, ni_bindsID, bindsArr);

    /*
     * Windows doesn't have virtual interfaces, so child array
     * is always empty.
     */
    childArr = (*env)->NewObjectArray(env, 0, ni_class, NULL);
    if (childArr == NULL) {
      return NULL;
    }
    (*env)->SetObjectField(env, netifObj, ni_childsID, childArr);

    /* return the NetworkInterface */
    return netifObj;
}

JNIEXPORT jobject JNICALL Java_java_net_NetworkInterface_getByName0_XP
    (JNIEnv *env, jclass cls, jstring name)
{
    netif *ifList, *curr;
    jboolean isCopy;
    const char *name_utf;
    jobject netifObj = NULL;

    if (getAllInterfacesAndAddresses (env, &ifList) < 0) {
        return NULL;
    }

    /* get the name as a C string */
    name_utf = (*env)->GetStringUTFChars(env, name, &isCopy);

    /* Search by name */
    curr = ifList;
    while (curr != NULL) {
        if (strcmp(name_utf, curr->name) == 0) {
            break;
        }
        curr = curr->next;
    }

    /* if found create a NetworkInterface */
    if (curr != NULL) {;
        netifObj = createNetworkInterfaceXP(env, curr);
    }

    /* release the UTF string */
    (*env)->ReleaseStringUTFChars(env, name, name_utf);

    /* release the interface list */
    free_netif(ifList);

    return netifObj;
}

/*
 * Class:     NetworkInterface
 * Method:    getByIndex0_XP
 * Signature: (I)LNetworkInterface;
 */
JNIEXPORT jobject JNICALL Java_java_net_NetworkInterface_getByIndex0_XP
  (JNIEnv *env, jclass cls, jint index)
{
    netif *ifList, *curr;
    jobject netifObj = NULL;

    if (getAllInterfacesAndAddresses (env, &ifList) < 0) {
        return NULL;
    }

    /* search by index */
    curr = ifList;
    while (curr != NULL) {
        if (index == curr->index) {
            break;
        }
        curr = curr->next;
    }

    /* if found create a NetworkInterface */
    if (curr != NULL) {
        netifObj = createNetworkInterfaceXP(env, curr);
    }

    /* release the interface list */
    free_netif(ifList);

    return netifObj;
}

/*
 * Class:     java_net_NetworkInterface
 * Method:    getByInetAddress0
 * Signature: (Ljava/net/InetAddress;)Ljava/net/NetworkInterface;
 */
JNIEXPORT jobject JNICALL Java_java_net_NetworkInterface_getByInetAddress0_XP
    (JNIEnv *env, jclass cls, jobject iaObj)
{
    netif *ifList, *curr;
    jobject netifObj = NULL;

    /* get the list of interfaces */
    if (getAllInterfacesAndAddresses (env, &ifList) < 0) {
        return NULL;
    }

    /*
     * Enumerate the addresses on each interface until we find a
     * matching address.
     */
    curr = ifList;
    while (curr != NULL) {
        netaddr *addrList = curr->addrs;
        netaddr *addrP;

        /* iterate through each address */
        addrP = addrList;

        while (addrP != NULL) {
            if (NET_SockaddrEqualsInetAddress(env,
                                (struct sockaddr*)&addrP->addr, iaObj)) {
                break;
            }
            addrP = addrP->next;
        }

        /*
         * Address matched so create NetworkInterface for this interface
         * and address list.
         */
        if (addrP != NULL) {
            netifObj = createNetworkInterfaceXP(env, curr);
            break;
        }

        /* on next interface */
        curr = curr->next;
    }

    /* release the interface list */
    free_netif(ifList);

    return netifObj;
}

/*
 * Class:     java_net_NetworkInterface
 * Method:    getAll
 * Signature: ()[Ljava/net/NetworkInterface;
 */
JNIEXPORT jobjectArray JNICALL Java_java_net_NetworkInterface_getAll_XP
    (JNIEnv *env, jclass cls)
{
    int count;
    netif *ifList, *curr;
    jobjectArray netIFArr;
    jint arr_index;

    /*
     * Get list of interfaces
     */
    count = getAllInterfacesAndAddresses (env, &ifList);
    if (count < 0) {
        return NULL;
    }

    /* allocate a NetworkInterface array */
    netIFArr = (*env)->NewObjectArray(env, count, cls, NULL);
    if (netIFArr == NULL) {
        return NULL;
    }

    /*
     * Iterate through the interfaces, create a NetworkInterface instance
     * for each array element and populate the object.
     */
    curr = ifList;
    arr_index = 0;
    while (curr != NULL) {
        jobject netifObj;

        netifObj = createNetworkInterfaceXP(env, curr);
        if (netifObj == NULL) {
            return NULL;
        }

        /* put the NetworkInterface into the array */
        (*env)->SetObjectArrayElement(env, netIFArr, arr_index++, netifObj);
        curr = curr->next;
    }

    /* release the interface list */
    free_netif(ifList);

    return netIFArr;
}

/*
 * Class:     java_net_NetworkInterface
 * Method:    supportsMulticast0
 * Signature: (Ljava/lang/String;I)Z
 */
JNIEXPORT jboolean JNICALL Java_java_net_NetworkInterface_supportsMulticast0_XP
    (JNIEnv *env, jclass cls, jstring name, jint index) {
      IP_ADAPTER_ADDRESSES *ptr;
      jboolean val = JNI_TRUE;

      ptr = getAdapter(env, index);
      if (ptr != NULL) {
        val = ptr->Flags & IP_ADAPTER_NO_MULTICAST ? JNI_FALSE : JNI_TRUE;
        free(ptr);
      }
      return val;
}

/*
 * Class:     java_net_NetworkInterface
 * Method:    isUp0
 * Signature: (Ljava/lang/String;I)Z
 */
JNIEXPORT jboolean JNICALL Java_java_net_NetworkInterface_isUp0_XP
    (JNIEnv *env, jclass cls, jstring name, jint index) {
      IP_ADAPTER_ADDRESSES *ptr;
      jboolean val = JNI_FALSE;

      ptr = getAdapter(env, index);
      if (ptr != NULL) {
        val = ptr->OperStatus == IfOperStatusUp ? JNI_TRUE : JNI_FALSE;
        free(ptr);
      }
      return val;
}

/*
 * Class:     java_net_NetworkInterface
 * Method:    getMacAddr0
 * Signature: (Ljava/lang/String;I)Z
 */
JNIEXPORT jbyteArray JNICALL Java_java_net_NetworkInterface_getMacAddr0_XP
    (JNIEnv *env, jclass cls, jstring name, jint index) {
      IP_ADAPTER_ADDRESSES *ptr;
      jbyteArray ret = NULL;
      int len;

      ptr = getAdapter(env, index);
      if (ptr != NULL) {
        len = ptr->PhysicalAddressLength;
        if (len > 0) {
          ret = (*env)->NewByteArray(env, len);
          if (!IS_NULL(ret)) {
            (*env)->SetByteArrayRegion(env, ret, 0, len,
                                       (jbyte*) ptr->PhysicalAddress);
          }
        }
        free(ptr);
      }
      return ret;
}

/*
 * Class:       java_net_NetworkInterface
 * Method:      getMTU0
 * Signature:   ([bLjava/lang/String;I)I
 */
JNIEXPORT jint JNICALL Java_java_net_NetworkInterface_getMTU0_XP
    (JNIEnv *env, jclass cls, jstring name, jint index) {
      IP_ADAPTER_ADDRESSES *ptr;
      jint ret = -1;

      ptr = getAdapter(env, index);
      if (ptr != NULL) {
        ret = ptr->Mtu;
        free(ptr);
      }
      return ret;
}

/*
 * Class:     java_net_NetworkInterface
 * Method:    isLoopback0
 * Signature: (Ljava/lang/String;I)Z
 */
JNIEXPORT jboolean JNICALL Java_java_net_NetworkInterface_isLoopback0_XP
    (JNIEnv *env, jclass cls, jstring name, jint index) {
      IP_ADAPTER_ADDRESSES *ptr;
      jboolean val = JNI_FALSE;

      ptr = getAdapter(env, index);
      if (ptr != NULL) {
        val = ptr->IfType == IF_TYPE_SOFTWARE_LOOPBACK ? JNI_TRUE : JNI_FALSE;
        free(ptr);
      }
      return val;
}

/*
 * Class:     java_net_NetworkInterface
 * Method:    isP2P0
 * Signature: (Ljava/lang/String;I)Z
 */
JNIEXPORT jboolean JNICALL Java_java_net_NetworkInterface_isP2P0_XP
    (JNIEnv *env, jclass cls, jstring name, jint index) {
      IP_ADAPTER_ADDRESSES *ptr;
      jboolean val = JNI_FALSE;

      ptr = getAdapter(env, index);
      if (ptr != NULL) {
        if (ptr->IfType == IF_TYPE_PPP || ptr->IfType == IF_TYPE_SLIP ||
           ptr->IfType == IF_TYPE_TUNNEL) {
          val = JNI_TRUE;
        }
        free(ptr);
      }
      return val;
}

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