Move attach*Filter() and addArpEntry() methods to NetworkStack

The SocketUtils.attach*Filter and SocketUtils.addArpEntry methods
were added there because they could not be added as JNI inside
the NetworkStack. This was not possible because on Go devices,
the NetworkStack was a jar library. But now, Go also uses an APK.
Hence, move these methods to the NetworkStack.

Fixes: 129433183
Merged-In: I66d7b3e4fbfa32bb0bc853e8cf9399031daff8a9
(cherry picked from commit fe71be2b04a3213828dc0347a1dd4a3675d20562)

Change-Id: Ice433a41469e784385f19498c154345d7b9c69b5
diff --git a/packages/NetworkStack/Android.bp b/packages/NetworkStack/Android.bp
index 57a3db5..262e6f6 100644
--- a/packages/NetworkStack/Android.bp
+++ b/packages/NetworkStack/Android.bp
@@ -49,6 +49,27 @@
     manifest: "AndroidManifestBase.xml",
 }
 
+cc_library_shared {
+    name: "libnetworkstackutilsjni",
+    srcs: [
+        "jni/network_stack_utils_jni.cpp"
+    ],
+
+    shared_libs: [
+        "liblog",
+        "libcutils",
+        "libnativehelper",
+    ],
+    static_libs: [
+        "libpcap",
+    ],
+    cflags: [
+        "-Wall",
+        "-Werror",
+        "-Wno-unused-parameter",
+    ],
+}
+
 java_defaults {
     name: "NetworkStackAppCommon",
     defaults: ["NetworkStackCommon"],
@@ -56,6 +77,7 @@
     static_libs: [
         "NetworkStackBase",
     ],
+    jni_libs: ["libnetworkstackutilsjni"],
     // Resources already included in NetworkStackBase
     resource_dirs: [],
     jarjar_rules: "jarjar-rules-shared.txt",
diff --git a/packages/NetworkStack/jni/network_stack_utils_jni.cpp b/packages/NetworkStack/jni/network_stack_utils_jni.cpp
new file mode 100644
index 0000000..5544eaa
--- /dev/null
+++ b/packages/NetworkStack/jni/network_stack_utils_jni.cpp
@@ -0,0 +1,264 @@
+/*
+ * Copyright 2019, The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#define LOG_TAG "NetworkStackUtils-JNI"
+
+#include <errno.h>
+#include <jni.h>
+#include <linux/filter.h>
+#include <linux/if_arp.h>
+#include <net/if.h>
+#include <netinet/ether.h>
+#include <netinet/icmp6.h>
+#include <netinet/ip.h>
+#include <netinet/ip6.h>
+#include <netinet/udp.h>
+#include <stdlib.h>
+
+#include <string>
+
+#include <nativehelper/JNIHelp.h>
+#include <utils/Log.h>
+
+namespace android {
+constexpr const char NETWORKSTACKUTILS_PKG_NAME[] = "android/net/util/NetworkStackUtils";
+
+static const uint32_t kEtherTypeOffset = offsetof(ether_header, ether_type);
+static const uint32_t kEtherHeaderLen = sizeof(ether_header);
+static const uint32_t kIPv4Protocol = kEtherHeaderLen + offsetof(iphdr, protocol);
+static const uint32_t kIPv4FlagsOffset = kEtherHeaderLen + offsetof(iphdr, frag_off);
+static const uint32_t kIPv6NextHeader = kEtherHeaderLen + offsetof(ip6_hdr, ip6_nxt);
+static const uint32_t kIPv6PayloadStart = kEtherHeaderLen + sizeof(ip6_hdr);
+static const uint32_t kICMPv6TypeOffset = kIPv6PayloadStart + offsetof(icmp6_hdr, icmp6_type);
+static const uint32_t kUDPSrcPortIndirectOffset = kEtherHeaderLen + offsetof(udphdr, source);
+static const uint32_t kUDPDstPortIndirectOffset = kEtherHeaderLen + offsetof(udphdr, dest);
+static const uint16_t kDhcpClientPort = 68;
+
+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 network_stack_utils_addArpEntry(JNIEnv *env, jobject thiz, jbyteArray ethAddr,
+        jbyteArray ipv4Addr, jstring ifname, jobject javaFd) {
+    arpreq req = {};
+    sockaddr_in& netAddrStruct = *reinterpret_cast<sockaddr_in*>(&req.arp_pa);
+    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;
+    }
+}
+
+static void network_stack_utils_attachDhcpFilter(JNIEnv *env, jobject clazz, jobject javaFd) {
+    static sock_filter filter_code[] = {
+        // Check the protocol is UDP.
+        BPF_STMT(BPF_LD  | BPF_B    | BPF_ABS, kIPv4Protocol),
+        BPF_JUMP(BPF_JMP | BPF_JEQ  | BPF_K,   IPPROTO_UDP, 0, 6),
+
+        // Check this is not a fragment.
+        BPF_STMT(BPF_LD  | BPF_H    | BPF_ABS, kIPv4FlagsOffset),
+        BPF_JUMP(BPF_JMP | BPF_JSET | BPF_K,   IP_OFFMASK, 4, 0),
+
+        // Get the IP header length.
+        BPF_STMT(BPF_LDX | BPF_B    | BPF_MSH, kEtherHeaderLen),
+
+        // Check the destination port.
+        BPF_STMT(BPF_LD  | BPF_H    | BPF_IND, kUDPDstPortIndirectOffset),
+        BPF_JUMP(BPF_JMP | BPF_JEQ  | BPF_K,   kDhcpClientPort, 0, 1),
+
+        // Accept or reject.
+        BPF_STMT(BPF_RET | BPF_K,              0xffff),
+        BPF_STMT(BPF_RET | BPF_K,              0)
+    };
+    static const sock_fprog filter = {
+        sizeof(filter_code) / sizeof(filter_code[0]),
+        filter_code,
+    };
+
+    int fd = jniGetFDFromFileDescriptor(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));
+    }
+}
+
+static void network_stack_utils_attachRaFilter(JNIEnv *env, jobject clazz, jobject javaFd,
+        jint hardwareAddressType) {
+    if (hardwareAddressType != ARPHRD_ETHER) {
+        jniThrowExceptionFmt(env, "java/net/SocketException",
+                "attachRaFilter only supports ARPHRD_ETHER");
+        return;
+    }
+
+    static sock_filter filter_code[] = {
+        // Check IPv6 Next Header is ICMPv6.
+        BPF_STMT(BPF_LD  | BPF_B   | BPF_ABS,  kIPv6NextHeader),
+        BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K,    IPPROTO_ICMPV6, 0, 3),
+
+        // Check ICMPv6 type is Router Advertisement.
+        BPF_STMT(BPF_LD  | BPF_B   | BPF_ABS,  kICMPv6TypeOffset),
+        BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K,    ND_ROUTER_ADVERT, 0, 1),
+
+        // Accept or reject.
+        BPF_STMT(BPF_RET | BPF_K,              0xffff),
+        BPF_STMT(BPF_RET | BPF_K,              0)
+    };
+    static const sock_fprog filter = {
+        sizeof(filter_code) / sizeof(filter_code[0]),
+        filter_code,
+    };
+
+    int fd = jniGetFDFromFileDescriptor(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));
+    }
+}
+
+// TODO: Move all this filter code into libnetutils.
+static void network_stack_utils_attachControlPacketFilter(
+        JNIEnv *env, jobject clazz, jobject javaFd, jint hardwareAddressType) {
+    if (hardwareAddressType != ARPHRD_ETHER) {
+        jniThrowExceptionFmt(env, "java/net/SocketException",
+                "attachControlPacketFilter only supports ARPHRD_ETHER");
+        return;
+    }
+
+    // Capture all:
+    //     - ARPs
+    //     - DHCPv4 packets
+    //     - Router Advertisements & Solicitations
+    //     - Neighbor Advertisements & Solicitations
+    //
+    // tcpdump:
+    //     arp or
+    //     '(ip and udp port 68)' or
+    //     '(icmp6 and ip6[40] >= 133 and ip6[40] <= 136)'
+    static sock_filter filter_code[] = {
+        // Load the link layer next payload field.
+        BPF_STMT(BPF_LD  | BPF_H    | BPF_ABS,  kEtherTypeOffset),
+
+        // Accept all ARP.
+        // TODO: Figure out how to better filter ARPs on noisy networks.
+        BPF_JUMP(BPF_JMP | BPF_JEQ  | BPF_K,   ETHERTYPE_ARP, 16, 0),
+
+        // If IPv4:
+        BPF_JUMP(BPF_JMP | BPF_JEQ  | BPF_K,   ETHERTYPE_IP, 0, 9),
+
+        // Check the protocol is UDP.
+        BPF_STMT(BPF_LD  | BPF_B    | BPF_ABS, kIPv4Protocol),
+        BPF_JUMP(BPF_JMP | BPF_JEQ  | BPF_K,   IPPROTO_UDP, 0, 14),
+
+        // Check this is not a fragment.
+        BPF_STMT(BPF_LD  | BPF_H    | BPF_ABS, kIPv4FlagsOffset),
+        BPF_JUMP(BPF_JMP | BPF_JSET | BPF_K,   IP_OFFMASK, 12, 0),
+
+        // Get the IP header length.
+        BPF_STMT(BPF_LDX | BPF_B    | BPF_MSH, kEtherHeaderLen),
+
+        // Check the source port.
+        BPF_STMT(BPF_LD  | BPF_H    | BPF_IND, kUDPSrcPortIndirectOffset),
+        BPF_JUMP(BPF_JMP | BPF_JEQ  | BPF_K,   kDhcpClientPort, 8, 0),
+
+        // Check the destination port.
+        BPF_STMT(BPF_LD  | BPF_H    | BPF_IND, kUDPDstPortIndirectOffset),
+        BPF_JUMP(BPF_JMP | BPF_JEQ  | BPF_K,   kDhcpClientPort, 6, 7),
+
+        // IPv6 ...
+        BPF_JUMP(BPF_JMP | BPF_JEQ  | BPF_K,   ETHERTYPE_IPV6, 0, 6),
+        // ... check IPv6 Next Header is ICMPv6 (ignore fragments), ...
+        BPF_STMT(BPF_LD  | BPF_B    | BPF_ABS, kIPv6NextHeader),
+        BPF_JUMP(BPF_JMP | BPF_JEQ  | BPF_K,   IPPROTO_ICMPV6, 0, 4),
+        // ... and check the ICMPv6 type is one of RS/RA/NS/NA.
+        BPF_STMT(BPF_LD  | BPF_B    | BPF_ABS, kICMPv6TypeOffset),
+        BPF_JUMP(BPF_JMP | BPF_JGE  | BPF_K,   ND_ROUTER_SOLICIT, 0, 2),
+        BPF_JUMP(BPF_JMP | BPF_JGT  | BPF_K,   ND_NEIGHBOR_ADVERT, 1, 0),
+
+        // Accept or reject.
+        BPF_STMT(BPF_RET | BPF_K,              0xffff),
+        BPF_STMT(BPF_RET | BPF_K,              0)
+    };
+    static const sock_fprog filter = {
+        sizeof(filter_code) / sizeof(filter_code[0]),
+        filter_code,
+    };
+
+    int fd = jniGetFDFromFileDescriptor(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));
+    }
+}
+
+/*
+ * JNI registration.
+ */
+static const JNINativeMethod gNetworkStackUtilsMethods[] = {
+    /* name, signature, funcPtr */
+    { "addArpEntry", "([B[BLjava/lang/String;Ljava/io/FileDescriptor;)V", (void*) network_stack_utils_addArpEntry },
+    { "attachDhcpFilter", "(Ljava/io/FileDescriptor;)V", (void*) network_stack_utils_attachDhcpFilter },
+    { "attachRaFilter", "(Ljava/io/FileDescriptor;I)V", (void*) network_stack_utils_attachRaFilter },
+    { "attachControlPacketFilter", "(Ljava/io/FileDescriptor;I)V", (void*) network_stack_utils_attachControlPacketFilter },
+};
+
+extern "C" jint JNI_OnLoad(JavaVM* vm, void*) {
+    JNIEnv *env;
+    if (vm->GetEnv(reinterpret_cast<void**>(&env), JNI_VERSION_1_6) != JNI_OK) {
+        ALOGE("ERROR: GetEnv failed");
+        return JNI_ERR;
+    }
+
+    if (jniRegisterNativeMethods(env, NETWORKSTACKUTILS_PKG_NAME,
+            gNetworkStackUtilsMethods, NELEM(gNetworkStackUtilsMethods)) < 0) {
+        return JNI_ERR;
+    }
+
+    return JNI_VERSION_1_6;
+
+}
+}; // namespace android
\ No newline at end of file
diff --git a/packages/NetworkStack/src/android/net/apf/ApfFilter.java b/packages/NetworkStack/src/android/net/apf/ApfFilter.java
index d2f3259..663e2f1 100644
--- a/packages/NetworkStack/src/android/net/apf/ApfFilter.java
+++ b/packages/NetworkStack/src/android/net/apf/ApfFilter.java
@@ -49,7 +49,6 @@
 import android.net.metrics.RaEvent;
 import android.net.util.InterfaceParams;
 import android.net.util.NetworkStackUtils;
-import android.net.util.SocketUtils;
 import android.os.PowerManager;
 import android.os.SystemClock;
 import android.system.ErrnoException;
@@ -478,7 +477,7 @@
             SocketAddress addr = makePacketSocketAddress(
                     (short) ETH_P_IPV6, mInterfaceParams.index);
             Os.bind(socket, addr);
-            SocketUtils.attachRaFilter(socket, mApfCapabilities.apfPacketFormat);
+            NetworkStackUtils.attachRaFilter(socket, mApfCapabilities.apfPacketFormat);
         } catch(SocketException|ErrnoException e) {
             Log.e(TAG, "Error starting filter", e);
             return;
diff --git a/packages/NetworkStack/src/android/net/dhcp/DhcpClient.java b/packages/NetworkStack/src/android/net/dhcp/DhcpClient.java
index 79d6a55..64adc0d 100644
--- a/packages/NetworkStack/src/android/net/dhcp/DhcpClient.java
+++ b/packages/NetworkStack/src/android/net/dhcp/DhcpClient.java
@@ -51,6 +51,7 @@
 import android.net.metrics.DhcpErrorEvent;
 import android.net.metrics.IpConnectivityLog;
 import android.net.util.InterfaceParams;
+import android.net.util.NetworkStackUtils;
 import android.net.util.SocketUtils;
 import android.os.Message;
 import android.os.SystemClock;
@@ -319,7 +320,7 @@
             mPacketSock = Os.socket(AF_PACKET, SOCK_RAW, ETH_P_IP);
             SocketAddress addr = makePacketSocketAddress((short) ETH_P_IP, mIface.index);
             Os.bind(mPacketSock, addr);
-            SocketUtils.attachDhcpFilter(mPacketSock);
+            NetworkStackUtils.attachDhcpFilter(mPacketSock);
         } catch(SocketException|ErrnoException e) {
             Log.e(TAG, "Error creating packet socket", e);
             return false;
diff --git a/packages/NetworkStack/src/android/net/dhcp/DhcpServer.java b/packages/NetworkStack/src/android/net/dhcp/DhcpServer.java
index cd993e9..8832eaa 100644
--- a/packages/NetworkStack/src/android/net/dhcp/DhcpServer.java
+++ b/packages/NetworkStack/src/android/net/dhcp/DhcpServer.java
@@ -45,6 +45,7 @@
 import android.net.INetworkStackStatusCallback;
 import android.net.MacAddress;
 import android.net.TrafficStats;
+import android.net.util.NetworkStackUtils;
 import android.net.util.SharedLog;
 import android.net.util.SocketUtils;
 import android.os.Handler;
@@ -207,7 +208,7 @@
         @Override
         public void addArpEntry(@NonNull Inet4Address ipv4Addr, @NonNull MacAddress ethAddr,
                 @NonNull String ifname, @NonNull FileDescriptor fd) throws IOException {
-            SocketUtils.addArpEntry(ipv4Addr, ethAddr, ifname, fd);
+            NetworkStackUtils.addArpEntry(ipv4Addr, ethAddr, ifname, fd);
         }
 
         @Override
diff --git a/packages/NetworkStack/src/android/net/ip/ConnectivityPacketTracker.java b/packages/NetworkStack/src/android/net/ip/ConnectivityPacketTracker.java
index de54824..eb49218 100644
--- a/packages/NetworkStack/src/android/net/ip/ConnectivityPacketTracker.java
+++ b/packages/NetworkStack/src/android/net/ip/ConnectivityPacketTracker.java
@@ -25,8 +25,8 @@
 
 import android.net.util.ConnectivityPacketSummary;
 import android.net.util.InterfaceParams;
+import android.net.util.NetworkStackUtils;
 import android.net.util.PacketReader;
-import android.net.util.SocketUtils;
 import android.os.Handler;
 import android.system.ErrnoException;
 import android.system.Os;
@@ -103,7 +103,7 @@
             FileDescriptor s = null;
             try {
                 s = Os.socket(AF_PACKET, SOCK_RAW | SOCK_NONBLOCK, 0);
-                SocketUtils.attachControlPacketFilter(s, ARPHRD_ETHER);
+                NetworkStackUtils.attachControlPacketFilter(s, ARPHRD_ETHER);
                 Os.bind(s, makePacketSocketAddress((short) ETH_P_ALL, mInterface.index));
             } catch (ErrnoException | IOException e) {
                 logError("Failed to create packet tracking socket: ", e);
diff --git a/packages/NetworkStack/src/android/net/util/NetworkStackUtils.java b/packages/NetworkStack/src/android/net/util/NetworkStackUtils.java
index 9d2df57..dada61c 100644
--- a/packages/NetworkStack/src/android/net/util/NetworkStackUtils.java
+++ b/packages/NetworkStack/src/android/net/util/NetworkStackUtils.java
@@ -23,14 +23,18 @@
 
 import java.io.FileDescriptor;
 import java.io.IOException;
+import java.net.Inet4Address;
+import java.net.SocketException;
 import java.util.List;
 import java.util.function.Predicate;
 
-
 /**
  * Collection of utilities for the network stack.
  */
 public class NetworkStackUtils {
+    static {
+        System.loadLibrary("networkstackutilsjni");
+    }
 
     /**
      * @return True if the array is null or 0-length.
@@ -98,4 +102,39 @@
         String value = DeviceConfig.getProperty(namespace, name);
         return value != null ? value : defaultValue;
     }
+
+    /**
+     * Attaches a socket filter that accepts DHCP packets to the given socket.
+     */
+    public static native void attachDhcpFilter(FileDescriptor fd) throws SocketException;
+
+    /**
+     * 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 static native void attachRaFilter(FileDescriptor fd, int packetType)
+            throws SocketException;
+
+    /**
+     * Attaches a socket filter that accepts L2-L4 signaling traffic required for IP connectivity.
+     *
+     * This includes: all ARP, ICMPv6 RS/RA/NS/NA messages, and DHCPv4 exchanges.
+     *
+     * @param fd the socket's {@link FileDescriptor}.
+     * @param packetType the hardware address type, one of ARPHRD_*.
+     */
+    public static native void attachControlPacketFilter(FileDescriptor fd, int packetType)
+            throws SocketException;
+
+    /**
+     * Add an entry into the ARP cache.
+     */
+    public static void addArpEntry(Inet4Address ipv4Addr, android.net.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;
 }
diff --git a/packages/NetworkStack/tests/Android.bp b/packages/NetworkStack/tests/Android.bp
index d0f419c..fe3c1e8 100644
--- a/packages/NetworkStack/tests/Android.bp
+++ b/packages/NetworkStack/tests/Android.bp
@@ -57,6 +57,7 @@
         "liblzma",
         "libnativehelper",
         "libnetworkstacktestsjni",
+        "libnetworkstackutilsjni",
         "libpackagelistparser",
         "libpcre2",
         "libprocessgroup",