Merge "Fix typo in IpConfiguration comment"
diff --git a/core/java/android/net/NetworkUtils.java b/core/java/android/net/NetworkUtils.java
index 599ccb2..34e9476 100644
--- a/core/java/android/net/NetworkUtils.java
+++ b/core/java/android/net/NetworkUtils.java
@@ -22,6 +22,7 @@
 import android.util.Pair;
 
 import java.io.FileDescriptor;
+import java.io.IOException;
 import java.math.BigInteger;
 import java.net.Inet4Address;
 import java.net.Inet6Address;
@@ -131,6 +132,17 @@
     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)}
      *             or {@link #intToInet4AddressHTL(int)}
@@ -149,7 +161,7 @@
      * @param hostAddress an int coding for an IPv4 address, where higher-order int byte is
      *                    lower-order IPv4 address byte
      */
-    public static InetAddress intToInet4AddressHTL(int hostAddress) {
+    public static Inet4Address intToInet4AddressHTL(int hostAddress) {
         return intToInet4AddressHTH(Integer.reverseBytes(hostAddress));
     }
 
@@ -157,14 +169,14 @@
      * Convert a IPv4 address from an integer to an InetAddress (0x01020304 -> 1.2.3.4)
      * @param hostAddress an int coding for an IPv4 address
      */
-    public static InetAddress intToInet4AddressHTH(int hostAddress) {
+    public static Inet4Address intToInet4AddressHTH(int hostAddress) {
         byte[] addressBytes = { (byte) (0xff & (hostAddress >> 24)),
                 (byte) (0xff & (hostAddress >> 16)),
                 (byte) (0xff & (hostAddress >> 8)),
                 (byte) (0xff & hostAddress) };
 
         try {
-            return InetAddress.getByAddress(addressBytes);
+            return (Inet4Address) InetAddress.getByAddress(addressBytes);
         } catch (UnknownHostException e) {
             throw new AssertionError();
         }
@@ -397,6 +409,28 @@
     }
 
     /**
+     * Get a prefix mask as Inet4Address for a given prefix length.
+     *
+     * <p>For example 20 -> 255.255.240.0
+     */
+    public static Inet4Address getPrefixMaskAsInet4Address(int prefixLength)
+            throws IllegalArgumentException {
+        return intToInet4AddressHTH(prefixLengthToV4NetmaskIntHTH(prefixLength));
+    }
+
+    /**
+     * Get the broadcast address for a given prefix.
+     *
+     * <p>For example 192.168.0.1/24 -> 192.168.0.255
+     */
+    public static Inet4Address getBroadcastAddress(Inet4Address addr, int prefixLength)
+            throws IllegalArgumentException {
+        final int intBroadcastAddr = inet4AddressToIntHTH(addr)
+                | ~prefixLengthToV4NetmaskIntHTH(prefixLength);
+        return intToInet4AddressHTH(intBroadcastAddr);
+    }
+
+    /**
      * Check if IP address type is consistent between two InetAddress.
      * @return true if both are the same type.  False otherwise.
      */
diff --git a/core/jni/android_net_NetUtils.cpp b/core/jni/android_net_NetUtils.cpp
index 823f1cc..9b138eb 100644
--- a/core/jni/android_net_NetUtils.cpp
+++ b/core/jni/android_net_NetUtils.cpp
@@ -323,6 +323,55 @@
     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 @@
     { "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 },
diff --git a/tests/net/java/android/net/NetworkUtilsTest.java b/tests/net/java/android/net/NetworkUtilsTest.java
index 2b172da..3452819 100644
--- a/tests/net/java/android/net/NetworkUtilsTest.java
+++ b/tests/net/java/android/net/NetworkUtilsTest.java
@@ -24,6 +24,8 @@
 import static android.net.NetworkUtils.netmaskToPrefixLength;
 import static android.net.NetworkUtils.prefixLengthToV4NetmaskIntHTH;
 import static android.net.NetworkUtils.prefixLengthToV4NetmaskIntHTL;
+import static android.net.NetworkUtils.getBroadcastAddress;
+import static android.net.NetworkUtils.getPrefixMaskAsInet4Address;
 
 import static junit.framework.Assert.assertEquals;
 
@@ -125,7 +127,6 @@
         assertInvalidNetworkMask(IPv4Address("255.255.0.255"));
     }
 
-
     @Test
     public void testPrefixLengthToV4NetmaskIntHTL() {
         assertEquals(0, prefixLengthToV4NetmaskIntHTL(0));
@@ -266,4 +267,44 @@
         assertEquals(BigInteger.valueOf(7l - 4 + 4 + 16 + 65536),
                 NetworkUtils.routedIPv6AddressCount(set));
     }
+
+    @Test
+    public void testGetPrefixMaskAsAddress() {
+        assertEquals("255.255.240.0", getPrefixMaskAsInet4Address(20).getHostAddress());
+        assertEquals("255.0.0.0", getPrefixMaskAsInet4Address(8).getHostAddress());
+        assertEquals("0.0.0.0", getPrefixMaskAsInet4Address(0).getHostAddress());
+        assertEquals("255.255.255.255", getPrefixMaskAsInet4Address(32).getHostAddress());
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void testGetPrefixMaskAsAddress_PrefixTooLarge() {
+        getPrefixMaskAsInet4Address(33);
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void testGetPrefixMaskAsAddress_NegativePrefix() {
+        getPrefixMaskAsInet4Address(-1);
+    }
+
+    @Test
+    public void testGetBroadcastAddress() {
+        assertEquals("192.168.15.255",
+                getBroadcastAddress(IPv4Address("192.168.0.123"), 20).getHostAddress());
+        assertEquals("192.255.255.255",
+                getBroadcastAddress(IPv4Address("192.168.0.123"), 8).getHostAddress());
+        assertEquals("192.168.0.123",
+                getBroadcastAddress(IPv4Address("192.168.0.123"), 32).getHostAddress());
+        assertEquals("255.255.255.255",
+                getBroadcastAddress(IPv4Address("192.168.0.123"), 0).getHostAddress());
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void testGetBroadcastAddress_PrefixTooLarge() {
+        getBroadcastAddress(IPv4Address("192.168.0.123"), 33);
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void testGetBroadcastAddress_NegativePrefix() {
+        getBroadcastAddress(IPv4Address("192.168.0.123"), -1);
+    }
 }