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Commit 12da4a5e authored by Remi NGUYEN VAN's avatar Remi NGUYEN VAN
Browse files

Add util to add an ARP table entry 

This is to be used by the new DhcpServer to add ARP entries with new
addresses before sending unicast responses.

Test: manual: cat /proc/net/arp with implementation based on this
Bug: b/109584964
Change-Id: I3559893583aa3c49b188ad689a41ee2f3e9d9bf3
parent c1413d0a

core/java/android/net/NetworkUtils.java

+12 −0
Original line number Diff line number Diff line
@@ -22,6 +22,7 @@ import android.util.Log; 
import android.util.Pair;



import java.io.FileDescriptor;

import java.io.IOException;

import java.math.BigInteger;

import java.net.Inet4Address;

import java.net.Inet6Address;
@@ -130,6 +131,17 @@ public class NetworkUtils { 
     */

    public native static boolean queryUserAccess(int uid, int netId);



    /**

     * Add an entry into the ARP cache.

     */

    public static void addArpEntry(Inet4Address ipv4Addr, MacAddress ethAddr, String ifname,

            FileDescriptor fd) throws IOException {

        addArpEntry(ethAddr.toByteArray(), ipv4Addr.getAddress(), ifname, fd);

    }



    private static native void addArpEntry(byte[] ethAddr, byte[] netAddr, String ifname,

            FileDescriptor fd) throws IOException;



    /**

     * @see #intToInet4AddressHTL(int)

     * @deprecated Use either {@link #intToInet4AddressHTH(int)}

core/jni/android_net_NetUtils.cpp

+50 −0
Original line number Diff line number Diff line
@@ -323,6 +323,55 @@ static jboolean android_net_utils_queryUserAccess(JNIEnv *env, jobject thiz, jin 
    return (jboolean) !queryUserAccess(uid, netId);

}



static bool checkLenAndCopy(JNIEnv* env, const jbyteArray& addr, int len, void* dst)

{

    if (env->GetArrayLength(addr) != len) {

        return false;

    }

    env->GetByteArrayRegion(addr, 0, len, reinterpret_cast<jbyte*>(dst));

    return true;

}



static void android_net_utils_addArpEntry(JNIEnv *env, jobject thiz, jbyteArray ethAddr,

        jbyteArray ipv4Addr, jstring ifname, jobject javaFd)

{

    struct arpreq req = {};

    struct sockaddr_in& netAddrStruct = *reinterpret_cast<sockaddr_in*>(&req.arp_pa);

    struct sockaddr& ethAddrStruct = req.arp_ha;



    ethAddrStruct.sa_family = ARPHRD_ETHER;

    if (!checkLenAndCopy(env, ethAddr, ETH_ALEN, ethAddrStruct.sa_data)) {

        jniThrowException(env, "java/io/IOException", "Invalid ethAddr length");

        return;

    }



    netAddrStruct.sin_family = AF_INET;

    if (!checkLenAndCopy(env, ipv4Addr, sizeof(in_addr), &netAddrStruct.sin_addr)) {

        jniThrowException(env, "java/io/IOException", "Invalid ipv4Addr length");

        return;

    }



    int ifLen = env->GetStringLength(ifname);

    // IFNAMSIZ includes the terminating NULL character

    if (ifLen >= IFNAMSIZ) {

        jniThrowException(env, "java/io/IOException", "ifname too long");

        return;

    }

    env->GetStringUTFRegion(ifname, 0, ifLen, req.arp_dev);



    req.arp_flags = ATF_COM;  // Completed entry (ha valid)

    int fd = jniGetFDFromFileDescriptor(env, javaFd);

    if (fd < 0) {

        jniThrowExceptionFmt(env, "java/io/IOException", "Invalid file descriptor");

        return;

    }

    // See also: man 7 arp

    if (ioctl(fd, SIOCSARP, &req)) {

        jniThrowExceptionFmt(env, "java/io/IOException", "ioctl error: %s", strerror(errno));

        return;

    }

}





// ----------------------------------------------------------------------------
@@ -337,6 +386,7 @@ static const JNINativeMethod gNetworkUtilMethods[] = { 
    { "bindSocketToNetwork", "(II)I", (void*) android_net_utils_bindSocketToNetwork },

    { "protectFromVpn", "(I)Z", (void*)android_net_utils_protectFromVpn },

    { "queryUserAccess", "(II)Z", (void*)android_net_utils_queryUserAccess },

    { "addArpEntry", "([B[BLjava/lang/String;Ljava/io/FileDescriptor;)V", (void*) android_net_utils_addArpEntry },

    { "attachDhcpFilter", "(Ljava/io/FileDescriptor;)V", (void*) android_net_utils_attachDhcpFilter },

    { "attachRaFilter", "(Ljava/io/FileDescriptor;I)V", (void*) android_net_utils_attachRaFilter },

    { "attachControlPacketFilter", "(Ljava/io/FileDescriptor;I)V", (void*) android_net_utils_attachControlPacketFilter },