ApfFilter: systematically use u8, u16, u32 getters

This patch adds a getUint8 getter for ByteBuffers and changes ApfFilter
to make uses of getUint8/16/32 everywhere.

The return types of getUint16 is also changed from long to int, which
will expand gracefully to long as an unsigned int as it is guaranteed to
be positive after getUint16.

Test: ApfTest passes

(cherry picked from commit 995dd94673005b43d32456e2de5fda0090b23576)

Change-Id: I606ebc5aedfcacde400d27cc6bc37145769b122c

diff --git a/services/net/java/android/net/apf/ApfFilter.java b/services/net/java/android/net/apf/ApfFilter.java
index 957a8d3..18d69ec 100644 (file)
--- a/services/net/java/android/net/apf/ApfFilter.java
+++ b/services/net/java/android/net/apf/ApfFilter.java
@@ -379,16 +379,16 @@ public class ApfFilter {
         // TODO: Make this static once RA is its own class.
         private void prefixOptionToString(StringBuffer sb, int offset) {
             String prefix = IPv6AddresstoString(offset + 16);
-            int length = uint8(mPacket.get(offset + 2));
-            long valid = mPacket.getInt(offset + 4);
-            long preferred = mPacket.getInt(offset + 8);
+            int length = getUint8(mPacket, offset + 2);
+            long valid = getUint32(mPacket, offset + 4);
+            long preferred = getUint32(mPacket, offset + 8);
             sb.append(String.format("%s/%d %ds/%ds ", prefix, length, valid, preferred));
         }
 
         private void rdnssOptionToString(StringBuffer sb, int offset) {
-            int optLen = uint8(mPacket.get(offset + 1)) * 8;
+            int optLen = getUint8(mPacket, offset + 1) * 8;
             if (optLen < 24) return;  // Malformed or empty.
-            long lifetime = uint32(mPacket.getInt(offset + 4));
+            long lifetime = getUint32(mPacket, offset + 4);
             int numServers = (optLen - 8) / 16;
             sb.append("DNS ").append(lifetime).append("s");
             for (int server = 0; server < numServers; server++) {
@@ -402,7 +402,7 @@ public class ApfFilter {
                 sb.append(String.format("RA %s -> %s %ds ",
                         IPv6AddresstoString(IPV6_SRC_ADDR_OFFSET),
                         IPv6AddresstoString(IPV6_DEST_ADDR_OFFSET),
-                        uint16(mPacket.getShort(ICMP6_RA_ROUTER_LIFETIME_OFFSET))));
+                        getUint16(mPacket, ICMP6_RA_ROUTER_LIFETIME_OFFSET)));
                 for (int i: mPrefixOptionOffsets) {
                     prefixOptionToString(sb, i);
                 }
@@ -454,8 +454,8 @@ public class ApfFilter {
             // Sanity check packet in case a packet arrives before we attach RA filter
             // to our packet socket. b/29586253
             if (getUint16(mPacket, ETH_ETHERTYPE_OFFSET) != ETH_P_IPV6 ||
-                    uint8(mPacket.get(IPV6_NEXT_HEADER_OFFSET)) != IPPROTO_ICMPV6 ||
-                    uint8(mPacket.get(ICMP6_TYPE_OFFSET)) != ICMP6_ROUTER_ADVERTISEMENT) {
+                    getUint8(mPacket, IPV6_NEXT_HEADER_OFFSET) != IPPROTO_ICMPV6 ||
+                    getUint8(mPacket, ICMP6_TYPE_OFFSET) != ICMP6_ROUTER_ADVERTISEMENT) {
                 throw new InvalidRaException("Not an ICMP6 router advertisement");
             }
 
@@ -477,8 +477,8 @@ public class ApfFilter {
             mPacket.position(ICMP6_RA_OPTION_OFFSET);
             while (mPacket.hasRemaining()) {
                 final int position = mPacket.position();
-                final int optionType = uint8(mPacket.get(position));
-                final int optionLength = uint8(mPacket.get(position + 1)) * 8;
+                final int optionType = getUint8(mPacket, position);
+                final int optionLength = getUint8(mPacket, position + 1) * 8;
                 long lifetime;
                 switch (optionType) {
                     case ICMP6_PREFIX_OPTION_TYPE:
@@ -563,10 +563,10 @@ public class ApfFilter {
                 final long optionLifetime;
                 switch (lifetimeLength) {
                     case 2:
-                        optionLifetime = uint16(byteBuffer.getShort(offset));
+                        optionLifetime = getUint16(byteBuffer, offset);
                         break;
                     case 4:
-                        optionLifetime = uint32(byteBuffer.getInt(offset));
+                        optionLifetime = getUint32(byteBuffer, offset);
                         break;
                     default:
                         throw new IllegalStateException("bogus lifetime size " + lifetimeLength);
@@ -1162,7 +1162,11 @@ public class ApfFilter {
         return i & 0xffffffffL;
     }
 
-    private static long getUint16(ByteBuffer buffer, int position) {
+    private static int getUint8(ByteBuffer buffer, int position) {
+        return uint8(buffer.get(position));
+    }
+
+    private static int getUint16(ByteBuffer buffer, int position) {
         return uint16(buffer.getShort(position));
     }