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Sanity check ICMP6 router advertisement packets

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There is a chance a packet can slip by before we install the filter
on our socket listening for RAs, so add some basic sanity checking
to make sure we've recieved an RA.

Change-Id: I14cf84a0814896a41e00f50af376dfc4988d36cb
Fixes: 29586253
This commit is contained in:
Paul Jensen
2016-07-20 15:01:17 -04:00
parent 862f109dd5
commit 4b545b04f6
1 changed files with 11 additions and 0 deletions
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11
services/net/java/android/net/apf/ApfFilter.java
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@@ -192,6 +192,7 @@ public class ApfFilter {
private static final int ICMP6_TYPE_OFFSET = ETH_HEADER_LEN + IPV6_HEADER_LEN;
private static final int ICMP6_NEIGHBOR_ANNOUNCEMENT = 136;
private static final int ICMP6_ROUTER_ADVERTISEMENT = 134;
// NOTE: this must be added to the IPv4 header length in IPV4_HEADER_SIZE_MEMORY_SLOT
private static final int UDP_DESTINATION_PORT_OFFSET = ETH_HEADER_LEN + 2;
@@ -452,6 +453,16 @@ public class ApfFilter {
Ra(byte[] packet, int length) {
mPacket = ByteBuffer.wrap(Arrays.copyOf(packet, length));
mLastSeen = curTime();
// 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) {
throw new IllegalArgumentException("Not an ICMP6 router advertisement");
}
RaEvent.Builder builder = new RaEvent.Builder();
// Ignore the checksum.