Basic IPv6 Router Advertisement daemon

am: 1a1cb0e914

Change-Id: I242eb8e932581a537a47f31e3f16c7e776da91cf

core/java/android/net/NetworkUtils.java

@@ -45,12 +45,19 @@ public class NetworkUtils {
     public native static void attachDhcpFilter(FileDescriptor fd) throws SocketException;
 
     /**
-     * Attaches a socket filter that accepts ICMP6 router advertisement packets to the given socket.
+     * Attaches a socket filter that accepts ICMPv6 router advertisements to the given socket.
      * @param fd the socket's {@link FileDescriptor}.
      * @param packetType the hardware address type, one of ARPHRD_*.
      */
     public native static void attachRaFilter(FileDescriptor fd, int packetType) throws SocketException;
 
+    /**
+     * Configures a socket for receiving ICMPv6 router solicitations and sending advertisements.
+     * @param fd the socket's {@link FileDescriptor}.
+     * @param ifIndex the interface index.
+     */
+    public native static void setupRaSocket(FileDescriptor fd, int ifIndex) throws SocketException;
+
     /**
      * Binds the current process to the network designated by {@code netId}.  All sockets created
      * in the future (and not explicitly bound via a bound {@link SocketFactory} (see

core/jni/android_net_NetUtils.cpp

@@ -122,6 +122,99 @@ static void android_net_utils_attachRaFilter(JNIEnv *env, jobject clazz, jobject
     }
 }
 
+static void android_net_utils_setupRaSocket(JNIEnv *env, jobject clazz, jobject javaFd,
+        jint ifIndex)
+{
+    static const int kLinkLocalHopLimit = 255;
+
+    int fd = jniGetFDFromFileDescriptor(env, javaFd);
+
+    // Set an ICMPv6 filter that only passes Router Solicitations.
+    struct icmp6_filter rs_only;
+    ICMP6_FILTER_SETBLOCKALL(&rs_only);
+    ICMP6_FILTER_SETPASS(ND_ROUTER_SOLICIT, &rs_only);
+    socklen_t len = sizeof(rs_only);
+    if (setsockopt(fd, IPPROTO_ICMPV6, ICMP6_FILTER, &rs_only, len) != 0) {
+        jniThrowExceptionFmt(env, "java/net/SocketException",
+                "setsockopt(ICMP6_FILTER): %s", strerror(errno));
+        return;
+    }
+
+    // Most/all of the rest of these options can be set via Java code, but
+    // because we're here on account of setting an icmp6_filter go ahead
+    // and do it all natively for now.
+    //
+    // TODO: Consider moving these out to Java.
+
+    // Set the multicast hoplimit to 255 (link-local only).
+    int hops = kLinkLocalHopLimit;
+    len = sizeof(hops);
+    if (setsockopt(fd, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &hops, len) != 0) {
+        jniThrowExceptionFmt(env, "java/net/SocketException",
+                "setsockopt(IPV6_MULTICAST_HOPS): %s", strerror(errno));
+        return;
+    }
+
+    // Set the unicast hoplimit to 255 (link-local only).
+    hops = kLinkLocalHopLimit;
+    len = sizeof(hops);
+    if (setsockopt(fd, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &hops, len) != 0) {
+        jniThrowExceptionFmt(env, "java/net/SocketException",
+                "setsockopt(IPV6_UNICAST_HOPS): %s", strerror(errno));
+        return;
+    }
+
+    // Explicitly disable multicast loopback.
+    int off = 0;
+    len = sizeof(off);
+    if (setsockopt(fd, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, &off, len) != 0) {
+        jniThrowExceptionFmt(env, "java/net/SocketException",
+                "setsockopt(IPV6_MULTICAST_LOOP): %s", strerror(errno));
+        return;
+    }
+
+    // Specify the IPv6 interface to use for outbound multicast.
+    len = sizeof(ifIndex);
+    if (setsockopt(fd, IPPROTO_IPV6, IPV6_MULTICAST_IF, &ifIndex, len) != 0) {
+        jniThrowExceptionFmt(env, "java/net/SocketException",
+                "setsockopt(IPV6_MULTICAST_IF): %s", strerror(errno));
+        return;
+    }
+
+    // Additional options to be considered:
+    //     - IPV6_TCLASS
+    //     - IPV6_RECVPKTINFO
+    //     - IPV6_RECVHOPLIMIT
+
+    // Bind to [::].
+    const struct sockaddr_in6 sin6 = {
+            .sin6_family = AF_INET6,
+            .sin6_port = 0,
+            .sin6_flowinfo = 0,
+            .sin6_addr = IN6ADDR_ANY_INIT,
+            .sin6_scope_id = 0,
+    };
+    auto sa = reinterpret_cast<const struct sockaddr *>(&sin6);
+    len = sizeof(sin6);
+    if (bind(fd, sa, len) != 0) {
+        jniThrowExceptionFmt(env, "java/net/SocketException",
+                "bind(IN6ADDR_ANY): %s", strerror(errno));
+        return;
+    }
+
+    // Join the all-routers multicast group, ff02::2%index.
+    struct ipv6_mreq all_rtrs = {
+        .ipv6mr_multiaddr = {{{0xff,2,0,0,0,0,0,0,0,0,0,0,0,0,0,2}}},
+        .ipv6mr_interface = ifIndex,
+    };
+    len = sizeof(all_rtrs);
+    if (setsockopt(fd, IPPROTO_IPV6, IPV6_JOIN_GROUP, &all_rtrs, len) != 0) {
+        jniThrowExceptionFmt(env, "java/net/SocketException",
+                "setsockopt(IPV6_JOIN_GROUP): %s", strerror(errno));
+        return;
+    }
+}
+
 static jboolean android_net_utils_bindProcessToNetwork(JNIEnv *env, jobject thiz, jint netId)
 {
     return (jboolean) !setNetworkForProcess(netId);
@@ -170,6 +263,7 @@ static const JNINativeMethod gNetworkUtilMethods[] = {
     { "queryUserAccess", "(II)Z", (void*)android_net_utils_queryUserAccess },
     { "attachDhcpFilter", "(Ljava/io/FileDescriptor;)V", (void*) android_net_utils_attachDhcpFilter },
     { "attachRaFilter", "(Ljava/io/FileDescriptor;I)V", (void*) android_net_utils_attachRaFilter },
+    { "setupRaSocket", "(Ljava/io/FileDescriptor;I)V", (void*) android_net_utils_setupRaSocket },
 };
 
 int register_android_net_NetworkUtils(JNIEnv* env)