/*

 * Copyright (c) 2019, 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 <stdio.h>

#include <stddef.h>

#include <iprtrmib.h>

#include <time.h>

#include <assert.h>

#include <iphlpapi.h>

#include "jni_util.h"

#define MAX_STR_LEN         256

#define STS_NO_CONFIG       0x0             /* no configuration found */

#define STS_SL_FOUND        0x1             /* search list found */

#define STS_NS_FOUND        0x2             /* name servers found */

#define STS_ERROR           -1              /* error return  lodConfig failed memory allccation failure*/

#define IS_SL_FOUND(sts)    (sts & STS_SL_FOUND)

#define IS_NS_FOUND(sts)    (sts & STS_NS_FOUND)

/* JNI ids */

static jfieldID searchlistID;

static jfieldID nameserversID;

/*

 * Utility routine to append s2 to s1 with a space delimiter.

 *  strappend(s1="abc", "def")  => "abc def"

 *  strappend(s1="", "def")     => "def

 */

void strappend(char *s1, char *s2) {

    size_t len;

    if (s2[0] == '\0')                      /* nothing to append */

        return;

    len = strlen(s1)+1;

    if (s1[0] != 0)                         /* needs space character */

        len++;

    if (len + strlen(s2) > MAX_STR_LEN)     /* insufficient space */

        return;

    if (s1[0] != 0) {

        strcat(s1, " ");

    }

    strcat(s1, s2);

}

/*

 * Windows 2000/XP

 *

 * Use registry approach based on settings described in Appendix C

 * of "Microsoft Windows 2000 TCP/IP Implementation Details".

 *

 * DNS suffix list is obtained from SearchList registry setting. If

 * this is not specified we compile suffix list based on the

 * per-connection domain suffix.

 *

 * DNS name servers and domain settings are on a per-connection

 * basic. We therefore enumerate the network adapters to get the

 * names of each adapter and then query the corresponding registry

 * settings to obtain NameServer/DhcpNameServer and Domain/DhcpDomain.

 */

static int loadConfig(char *sl, char *ns) {

    IP_ADAPTER_INFO *adapterP;

    ULONG size;

    DWORD ret;

    DWORD dwLen;

    ULONG ulType;

    char result[MAX_STR_LEN];

    HANDLE hKey;

    int gotSearchList = 0;

    /*

     * First see if there is a global suffix list specified.

     */

    ret = RegOpenKeyEx(HKEY_LOCAL_MACHINE,

                       "SYSTEM\\CurrentControlSet\\Services\\Tcpip\\Parameters",

                       0,

                       KEY_READ,

                       (PHKEY)&hKey);

    if (ret == ERROR_SUCCESS) {

        dwLen = sizeof(result);

        ret = RegQueryValueEx(hKey, "SearchList", NULL, &ulType,

                             (LPBYTE)&result, &dwLen);

        if (ret == ERROR_SUCCESS) {

            assert(ulType == REG_SZ);

            if (strlen(result) > 0) {

                strappend(sl, result);

                gotSearchList = 1;

            }

        }

        RegCloseKey(hKey);

    }

    /*

     * Ask the IP Helper library to enumerate the adapters

     */

    size = sizeof(IP_ADAPTER_INFO);

    adapterP = (IP_ADAPTER_INFO *)malloc(size);

    if (adapterP == NULL) {

        return STS_ERROR;

    }

    ret = GetAdaptersInfo(adapterP, &size);

    if (ret == ERROR_BUFFER_OVERFLOW) {

        IP_ADAPTER_INFO *newAdapterP = (IP_ADAPTER_INFO *)realloc(adapterP, size);

        if (newAdapterP == NULL) {

            free(adapterP);

            return STS_ERROR;

        }

        adapterP = newAdapterP;

        ret = GetAdaptersInfo(adapterP, &size);

    }

    /*

     * Iterate through the list of adapters as registry settings are

     * keyed on the adapter name (GUID).

     */

    if (ret == ERROR_SUCCESS) {

        IP_ADAPTER_INFO *curr = adapterP;

        while (curr != NULL) {

            char key[MAX_STR_LEN];

            sprintf(key,

                "SYSTEM\\CurrentControlSet\\Services\\Tcpip\\Parameters\\Interfaces\\%s",

                curr->AdapterName);

            ret = RegOpenKeyEx(HKEY_LOCAL_MACHINE,

                               key,

                               0,

                               KEY_READ,

                               (PHKEY)&hKey);

            if (ret == ERROR_SUCCESS) {

                DWORD enableDhcp = 0;

                /*

                 * Is DHCP enabled on this interface

                 */

                dwLen = sizeof(enableDhcp);

                ret = RegQueryValueEx(hKey, "EnableDhcp", NULL, &ulType,

                                     (LPBYTE)&enableDhcp, &dwLen);

                /*

                 * If we don't have the suffix list when get the Domain

                 * or DhcpDomain. If DHCP is enabled then Domain overides

                 * DhcpDomain

                 */

                if (!gotSearchList) {

                    result[0] = '\0';

                    dwLen = sizeof(result);

                    ret = RegQueryValueEx(hKey, "Domain", NULL, &ulType,

                                         (LPBYTE)&result, &dwLen);

                    if (((ret != ERROR_SUCCESS) || (strlen(result) == 0)) &&

                        enableDhcp) {

                        dwLen = sizeof(result);

                        ret = RegQueryValueEx(hKey, "DhcpDomain", NULL, &ulType,

                                              (LPBYTE)&result, &dwLen);

                    }

                    if (ret == ERROR_SUCCESS) {

                        assert(ulType == REG_SZ);

                        strappend(sl, result);

                    }

                }

                /*

                 * Get DNS servers based on NameServer or DhcpNameServer

                 * registry setting. If NameServer is set then it overrides

                 * DhcpNameServer (even if DHCP is enabled).

                 */

                result[0] = '\0';

                dwLen = sizeof(result);

                ret = RegQueryValueEx(hKey, "NameServer", NULL, &ulType,

                                     (LPBYTE)&result, &dwLen);

                if (((ret != ERROR_SUCCESS) || (strlen(result) == 0)) &&

                    enableDhcp) {

                    dwLen = sizeof(result);

                    ret = RegQueryValueEx(hKey, "DhcpNameServer", NULL, &ulType,

                                          (LPBYTE)&result, &dwLen);

                }

                if (ret == ERROR_SUCCESS) {

                    assert(ulType == REG_SZ);

                    strappend(ns, result);

                }

                /*

                 * Finished with this registry key

                 */

                RegCloseKey(hKey);

            }

            /*

             * Onto the next adapeter

             */

            curr = curr->Next;

        }

    }

    /*

     * Free the adpater structure

     */

    if (adapterP) {

        free(adapterP);

    }

    return STS_SL_FOUND & STS_NS_FOUND;

}

/*

 * Initialize JNI field IDs.

 */

JNIEXPORT void JNICALL

Java_jdk_dns_conf_DnsResolverConfiguration_init0(JNIEnv *env, jclass cls)

{

    searchlistID = (*env)->GetStaticFieldID(env, cls, "os_searchlist",

                                      "Ljava/lang/String;");

    CHECK_NULL(searchlistID);

    nameserversID = (*env)->GetStaticFieldID(env, cls, "os_nameservers",

                                      "Ljava/lang/String;");

}

/*

 * Class:     jdk_dns_conf_DnsResolverConfguration

 * Method:    loadConfig0

 * Signature: ()V

 */

JNIEXPORT void JNICALL

Java_jdk_dns_conf_DnsResolverConfiguration_loadDNSconfig0(JNIEnv *env, jclass cls)

{

    char searchlist[MAX_STR_LEN];

    char nameservers[MAX_STR_LEN];

    jstring obj;

    searchlist[0] = '\0';

    nameservers[0] = '\0';

    if (loadConfig(searchlist, nameservers) != STS_ERROR) {

        /*

         * Populate static fields in jdk.dns.conf.ResolverConfiguration

         */

        obj = (*env)->NewStringUTF(env, searchlist);

        CHECK_NULL(obj);

        (*env)->SetStaticObjectField(env, cls, searchlistID, obj);

        obj = (*env)->NewStringUTF(env, nameservers);

        CHECK_NULL(obj);

        (*env)->SetStaticObjectField(env, cls, nameserversID, obj);

    } else {

        JNU_ThrowOutOfMemoryError(env, "native memory allocation failed");

    }

}

/*

 * Class:     jdk_dns_conf_DnsResolverConfiguration

 * Method:    notifyAddrChange0

 * Signature: ()I

 */

JNIEXPORT jint JNICALL

Java_jdk_dns_conf_DnsResolverConfiguration_notifyAddrChange0(JNIEnv *env, jclass cls)

{

    OVERLAPPED ol;

    HANDLE h;

    DWORD rc, xfer;

    ol.hEvent = (HANDLE)0;

    rc = NotifyAddrChange(&h, &ol);

    if (rc == ERROR_IO_PENDING) {

        rc = GetOverlappedResult(h, &ol, &xfer, TRUE);

        if (rc != 0) {

            return 0;   /* address changed */

        }

    }

    /* error */

    return -1;

}