src/java.base/windows/native/libnet/Inet4AddressImpl.c

/*
 * Copyright (c) 2000, 2025, 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 <malloc.h>

#include "net_util.h"

#include "java_net_InetAddress.h"
#include "java_net_Inet4AddressImpl.h"

/*
 * 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[256];

    if (gethostname(hostname, sizeof(hostname)) == -1) {
        strcpy(hostname, "localhost");
    }
    return JNU_NewStringPlatform(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_GetStringPlatformCharsStrict(env, host, NULL);
    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) {
        // report error
        int enh = getEnhancedExceptionsAllowed(env);
        if (enh == ENH_INIT_ERROR && (*env)->ExceptionCheck(env)) {
            goto cleanupAndReturn;
        }
        const char *hmsg = (enh == ENH_ENABLED) ? hostname : "";
        NET_ThrowByNameWithLastError( env, "java/net/UnknownHostException", hmsg);
        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: ([B)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, NI_MAXHOST, 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;
    WSAEVENT hEvent;

    // open a TCP socket
    fd = NET_Socket(AF_INET, SOCK_STREAM, 0);
    if (fd == SOCKET_ERROR) {
        // 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, WSAGetLastError(), "Can't create socket");
        return JNI_FALSE;
    }

    // set TTL
    if (ttl > 0) {
        if (setsockopt(fd, IPPROTO_IP, IP_TTL, (const char *)&ttl, sizeof(ttl)) == SOCKET_ERROR) {
            NET_ThrowNew(env, WSAGetLastError(), "setsockopt IP_TTL failed");
            closesocket(fd);
            return JNI_FALSE;
        }
    }

    // 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, WSAGetLastError(), "Can't bind socket");
            closesocket(fd);
            return JNI_FALSE;
        }
    }

    // Make the socket non blocking so we can use select/poll.
    hEvent = WSACreateEvent();
    WSAEventSelect(fd, hEvent, FD_READ|FD_CONNECT|FD_CLOSE);

    sa->sa4.sin_port = htons(7); // echo port
    connect_rv = 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 || WSAGetLastError() == WSAECONNREFUSED) {
        WSACloseEvent(hEvent);
        closesocket(fd);
        return JNI_TRUE;
    }

    switch (WSAGetLastError()) {
    case WSAEHOSTUNREACH:   // Host Unreachable
    case WSAENETUNREACH:    // Network Unreachable
    case WSAENETDOWN:       // Network is down
    case WSAEPFNOSUPPORT:   // Protocol Family unsupported
        WSACloseEvent(hEvent);
        closesocket(fd);
        return JNI_FALSE;
    case WSAEWOULDBLOCK:    // this is expected as we'll probably have to wait
        break;
    default:
        NET_ThrowByNameWithLastError(env, JNU_JAVANETPKG "ConnectException",
                                     "connect failed");
        WSACloseEvent(hEvent);
        closesocket(fd);
        return JNI_FALSE;
    }

    timeout = NET_Wait(env, fd, NET_WAIT_CONNECT, timeout);
    if (timeout >= 0) {
        // connection has been established, check for error condition
        int optlen = sizeof(connect_rv);
        if (getsockopt(fd, SOL_SOCKET, SO_ERROR, (void *)&connect_rv,
                       &optlen) < 0)
        {
            connect_rv = WSAGetLastError();
        }
        if (connect_rv == 0 || connect_rv == WSAECONNREFUSED) {
            WSACloseEvent(hEvent);
            closesocket(fd);
            return JNI_TRUE;
        }
    }
    WSACloseEvent(hEvent);
    closesocket(fd);
    return JNI_FALSE;
}

/**
 * ping implementation.
 * Send a ICMP_ECHO_REQUEST packet every second until either the timeout
 * expires or a answer is received.
 * Returns true is an ECHO_REPLY is received, otherwise, false.
 */
static jboolean
ping4(JNIEnv *env, HANDLE hIcmpFile, SOCKETADDRESS *sa,
      SOCKETADDRESS *netif, jint timeout)
{
    DWORD dwRetVal = 0;
    char SendData[32] = {0};
    LPVOID ReplyBuffer = NULL;
    DWORD ReplySize = 0;
    jboolean ret = JNI_FALSE;

    // See https://msdn.microsoft.com/en-us/library/aa366050%28VS.85%29.aspx
    // or https://msdn.microsoft.com/en-us/library/windows/desktop/aa366051%28v=vs.85%29.aspx
    ReplySize = sizeof(ICMP_ECHO_REPLY)   // The buffer should be large enough
                                          // to hold at least one ICMP_ECHO_REPLY
                                          // structure
                + sizeof(SendData)        // plus RequestSize bytes of data.
                + 8;                      // This buffer should also be large enough
                                          // to also hold 8 more bytes of data
                                          // (the size of an ICMP error message)

    ReplyBuffer = (VOID *)malloc(ReplySize);
    if (ReplyBuffer == NULL) {
        IcmpCloseHandle(hIcmpFile);
        NET_ThrowNew(env, -1, "Unable to allocate memory");
        return JNI_FALSE;
    }

    if (netif == NULL) {
        dwRetVal = IcmpSendEcho(hIcmpFile,  // HANDLE IcmpHandle,
                                sa->sa4.sin_addr.s_addr, // IPAddr DestinationAddress,
                                SendData,   // LPVOID RequestData,
                                sizeof(SendData),   // WORD RequestSize,
                                NULL,       // PIP_OPTION_INFORMATION RequestOptions,
                                ReplyBuffer,// LPVOID ReplyBuffer,
                                ReplySize,  // DWORD ReplySize,
                                // Note: IcmpSendEcho and its derivatives
                                // seem to have an undocumented minimum
                                // timeout of 1000ms below which the
                                // api behaves inconsistently.
                                (timeout < 1000) ? 1000 : timeout); // DWORD Timeout
    } else {
        dwRetVal = IcmpSendEcho2Ex(hIcmpFile,  // HANDLE IcmpHandle,
                                   NULL,       // HANDLE Event
                                   NULL,       // PIO_APC_ROUTINE ApcRoutine
                                   NULL,       // ApcContext
                                   netif->sa4.sin_addr.s_addr, // IPAddr SourceAddress,
                                   sa->sa4.sin_addr.s_addr, // IPAddr DestinationAddress,
                                   SendData,   // LPVOID RequestData,
                                   sizeof(SendData), // WORD RequestSize,
                                   NULL,       // PIP_OPTION_INFORMATION RequestOptions,
                                   ReplyBuffer,// LPVOID ReplyBuffer,
                                   ReplySize,  // DWORD ReplySize,
                                   (timeout < 1000) ? 1000 : timeout); // DWORD Timeout
    }

    if (dwRetVal == 0) { // if the call failed
        TCHAR *buf = NULL;
        DWORD n;
        DWORD err = WSAGetLastError();
        switch (err) {
            case ERROR_NO_NETWORK:
            case ERROR_NETWORK_UNREACHABLE:
            case ERROR_HOST_UNREACHABLE:
            case ERROR_PROTOCOL_UNREACHABLE:
            case ERROR_PORT_UNREACHABLE:
            case ERROR_REQUEST_ABORTED:
            case ERROR_INCORRECT_ADDRESS:
            case ERROR_HOST_DOWN:
            case ERROR_INVALID_COMPUTERNAME:
            case ERROR_INVALID_NETNAME:
            case WSAEHOSTUNREACH:   /* Host Unreachable */
            case WSAENETUNREACH:    /* Network Unreachable */
            case WSAENETDOWN:       /* Network is down */
            case WSAEPFNOSUPPORT:   /* Protocol Family unsupported */
            case IP_REQ_TIMED_OUT:
                break;
            default:
                n = FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER |
                        FORMAT_MESSAGE_FROM_SYSTEM,
                        NULL, err, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
                        (LPTSTR)&buf, 0, NULL);
                if (n > 3) {
                    // Drop final '.', CR, LF
                    if (buf[n - 1] == TEXT('\n')) n--;
                    if (buf[n - 1] == TEXT('\r')) n--;
                    if (buf[n - 1] == TEXT('.')) n--;
                    buf[n] = TEXT('\0');
                }
                NET_ThrowNew(env, err, buf);
                LocalFree(buf);
                break;
        }
    } else {
        PICMP_ECHO_REPLY pEchoReply = (PICMP_ECHO_REPLY)ReplyBuffer;

        // This is to take into account the undocumented minimum
        // timeout mentioned in the IcmpSendEcho call above.
        // We perform an extra check to make sure that our
        // roundtrip time was less than our desired timeout
        // for cases where that timeout is < 1000ms.
        if (pEchoReply->Status == IP_SUCCESS &&
            (int)pEchoReply->RoundTripTime <= timeout)
        {
            ret = JNI_TRUE;
        }
    }

    free(ReplyBuffer);
    IcmpCloseHandle(hIcmpFile);

    return ret;
}

/*
 * 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;
    SOCKETADDRESS sa, inf, *netif = NULL;
    HANDLE hIcmpFile;

    // 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 an ICMP handle.
    hIcmpFile = IcmpCreateFile();
    if (hIcmpFile == INVALID_HANDLE_VALUE) {
        int err = WSAGetLastError();
        if (err == ERROR_ACCESS_DENIED) {
            // fall back to TCP echo if access is denied to ICMP
            return tcp_ping4(env, &sa, netif, timeout, ttl);
        } else {
            NET_ThrowNew(env, err, "Unable to create ICMP file handle");
            return JNI_FALSE;
        }
    } else {
        // It didn't fail, so we can use ICMP.
        return ping4(env, hIcmpFile, &sa, netif, timeout);
    }
}