Update jni to get int descriptor in native layer

ConnectivityService is going to become a mainline module which
can not access the hidden APIs. The int descriptor of a
FileDescriptor is hidden for internal use only. The Network and
NetworkUtls will be parts of CS module. The corresponding usage
should be removed. There is no way in a module to access the
descriptor, so update the jni to set a FileDescriptor to native
to get the int descriptor inside the platform.

Also, update the other references in android_net_NetUtils for
getting fd to use the NDK functions in the libnativehelper.

Bug: 170598012
Test: atest FrameworksNetTests CtsNetTestCasesLatestSdk
Test: manually connect to a VPN
Change-Id: I2143c079feac53917a6e7bf7422f3180f51437fb

core/java/android/net/Network.java

@@ -420,7 +420,7 @@ public class Network implements Parcelable {
             throw new SocketException("Only AF_INET/AF_INET6 sockets supported");
         }
 
-        final int err = NetworkUtils.bindSocketToNetwork(fd.getInt$(), netId);
+        final int err = NetworkUtils.bindSocketToNetwork(fd, netId);
         if (err != 0) {
             // bindSocketToNetwork returns negative errno.
             throw new ErrnoException("Binding socket to network " + netId, -err)

core/java/android/net/NetworkUtils.java

@@ -81,11 +81,11 @@ public class NetworkUtils {
     public native static boolean bindProcessToNetworkForHostResolution(int netId);
 
     /**
-     * Explicitly binds {@code socketfd} to the network designated by {@code netId}.  This
+     * Explicitly binds {@code fd} to the network designated by {@code netId}.  This
      * overrides any binding via {@link #bindProcessToNetwork}.
      * @return 0 on success or negative errno on failure.
      */
-    public native static int bindSocketToNetwork(int socketfd, int netId);
+    public static native int bindSocketToNetwork(FileDescriptor fd, int netId);
 
     /**
      * Protect {@code fd} from VPN connections.  After protecting, data sent through
@@ -93,9 +93,7 @@ public class NetworkUtils {
      * forwarded through the VPN.
      */
     @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.R, trackingBug = 170729553)
-    public static boolean protectFromVpn(FileDescriptor fd) {
+    public static native boolean protectFromVpn(FileDescriptor fd);
-        return protectFromVpn(fd.getInt$());
-    }
 
     /**
      * Protect {@code socketfd} from VPN connections.  After protecting, data sent through

core/jni/android_net_NetUtils.cpp

@@ -18,6 +18,7 @@
 
 #include <vector>
 
+#include <android/file_descriptor_jni.h>
 #include <arpa/inet.h>
 #include <linux/filter.h>
 #include <linux/if_arp.h>
@@ -83,7 +84,7 @@ static void android_net_utils_attachDropAllBPFFilter(JNIEnv *env, jobject clazz,
         filter_code,
     };
 
-    int fd = jniGetFDFromFileDescriptor(env, javaFd);
+    int fd = AFileDescriptor_getFD(env, javaFd);
     if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &filter, sizeof(filter)) != 0) {
         jniThrowExceptionFmt(env, "java/net/SocketException",
                 "setsockopt(SO_ATTACH_FILTER): %s", strerror(errno));
@@ -93,7 +94,7 @@ static void android_net_utils_attachDropAllBPFFilter(JNIEnv *env, jobject clazz,
 static void android_net_utils_detachBPFFilter(JNIEnv *env, jobject clazz, jobject javaFd)
 {
     int optval_ignored = 0;
-    int fd = jniGetFDFromFileDescriptor(env, javaFd);
+    int fd = AFileDescriptor_getFD(env, javaFd);
     if (setsockopt(fd, SOL_SOCKET, SO_DETACH_FILTER, &optval_ignored, sizeof(optval_ignored)) !=
         0) {
         jniThrowExceptionFmt(env, "java/net/SocketException",
@@ -117,10 +118,9 @@ static jboolean android_net_utils_bindProcessToNetworkForHostResolution(JNIEnv *
     return (jboolean) !setNetworkForResolv(netId);
 }
 
-static jint android_net_utils_bindSocketToNetwork(JNIEnv *env, jobject thiz, jint socket,
+static jint android_net_utils_bindSocketToNetwork(JNIEnv *env, jobject thiz, jobject javaFd,
-        jint netId)
+                                                  jint netId) {
-{
+    return setNetworkForSocket(netId, AFileDescriptor_getFD(env, javaFd));
-    return setNetworkForSocket(netId, socket);
 }
 
 static jboolean android_net_utils_protectFromVpn(JNIEnv *env, jobject thiz, jint socket)
@@ -128,6 +128,10 @@ static jboolean android_net_utils_protectFromVpn(JNIEnv *env, jobject thiz, jint
     return (jboolean) !protectFromVpn(socket);
 }
 
+static jboolean android_net_utils_protectFromVpnWithFd(JNIEnv *env, jobject thiz, jobject javaFd) {
+    return android_net_utils_protectFromVpn(env, thiz, AFileDescriptor_getFD(env, javaFd));
+}
+
 static jboolean android_net_utils_queryUserAccess(JNIEnv *env, jobject thiz, jint uid, jint netId)
 {
     return (jboolean) !queryUserAccess(uid, netId);
@@ -178,7 +182,7 @@ static jobject android_net_utils_resNetworkSend(JNIEnv *env, jobject thiz, jint
 }
 
 static jobject android_net_utils_resNetworkResult(JNIEnv *env, jobject thiz, jobject javaFd) {
-    int fd = jniGetFDFromFileDescriptor(env, javaFd);
+    int fd = AFileDescriptor_getFD(env, javaFd);
     int rcode;
     std::vector<uint8_t> buf(MAXPACKETSIZE, 0);
 
@@ -205,7 +209,7 @@ static jobject android_net_utils_resNetworkResult(JNIEnv *env, jobject thiz, job
 }
 
 static void android_net_utils_resNetworkCancel(JNIEnv *env, jobject thiz, jobject javaFd) {
-    int fd = jniGetFDFromFileDescriptor(env, javaFd);
+    int fd = AFileDescriptor_getFD(env, javaFd);
     resNetworkCancel(fd);
     jniSetFileDescriptorOfFD(env, javaFd, -1);
 }
@@ -231,7 +235,7 @@ static jobject android_net_utils_getTcpRepairWindow(JNIEnv *env, jobject thiz, j
         return NULL;
     }
 
-    int fd = jniGetFDFromFileDescriptor(env, javaFd);
+    int fd = AFileDescriptor_getFD(env, javaFd);
     struct tcp_repair_window trw = {};
     socklen_t size = sizeof(trw);
 
@@ -271,8 +275,9 @@ static const JNINativeMethod gNetworkUtilMethods[] = {
     { "bindProcessToNetwork", "(I)Z", (void*) android_net_utils_bindProcessToNetwork },
     { "getBoundNetworkForProcess", "()I", (void*) android_net_utils_getBoundNetworkForProcess },
     { "bindProcessToNetworkForHostResolution", "(I)Z", (void*) android_net_utils_bindProcessToNetworkForHostResolution },
-    { "bindSocketToNetwork", "(II)I", (void*) android_net_utils_bindSocketToNetwork },
+    { "bindSocketToNetwork", "(Ljava/io/FileDescriptor;I)I", (void*) android_net_utils_bindSocketToNetwork },
-    { "protectFromVpn", "(I)Z", (void*)android_net_utils_protectFromVpn },
+    { "protectFromVpn", "(I)Z", (void*) android_net_utils_protectFromVpn },
+    { "protectFromVpn", "(Ljava/io/FileDescriptor;)Z", (void*) android_net_utils_protectFromVpnWithFd },
     { "queryUserAccess", "(II)Z", (void*)android_net_utils_queryUserAccess },
     { "attachDropAllBPFFilter", "(Ljava/io/FileDescriptor;)V", (void*) android_net_utils_attachDropAllBPFFilter },
     { "detachBPFFilter", "(Ljava/io/FileDescriptor;)V", (void*) android_net_utils_detachBPFFilter },