Add support for longest prefix match of IPPrefixes

* Implement IPPrefix.hashCode() and equals() for longest prefix match.

* Add withdrawnPrefixes to MPUnreachableNLRIAttribute.

2 files changed, 57 insertions, 3 deletions

diff --git a/src/main/java/com/lumaserv/bgp/protocol/IPPrefix.java b/src/main/java/com/lumaserv/bgp/protocol/IPPrefix.java
index 5d38cf6..57cfe90 100644
--- a/src/main/java/com/lumaserv/bgp/protocol/IPPrefix.java
+++ b/src/main/java/com/lumaserv/bgp/protocol/IPPrefix.java
@@ -15,6 +15,42 @@ public class IPPrefix {
     byte[] address;
     int length;
 
+    /**
+     * Include length bits from address in hash to allow longest
+     * prefix matches.
+     */
+    public int hashCode() {
+        int hash = length + address.length << 7;
+        final int bytes = (length+7)/8;
+        for (int i = 0; i < bytes; i++) {
+            hash += (int)address[i] << (i % 4) * 8;
+        }
+        return hash;
+    }
+
+    /**
+     * Include length bits from address in comparison to allow longest
+     * prefix matches.
+     */
+    public boolean equals(Object obj) {
+        if (!(obj instanceof IPPrefix))
+            return false;
+
+        IPPrefix other = (IPPrefix)obj;
+
+        if (length != other.length
+            || address.length != other.address.length)
+            return false;
+
+        final int bytes = (length+7)/8;
+        for (int i=0; i < bytes; i++) {
+            if (address[i] != other.address[i])
+                return false;
+        }
+
+        return true;
+    }
+
     public String toString() {
         try {
             return IPAddress.toString(InetAddress.getByAddress(address)) + "/" + length;
diff --git a/src/main/java/com/lumaserv/bgp/protocol/attribute/MPUnreachableNLRIAttribute.java b/src/main/java/com/lumaserv/bgp/protocol/attribute/MPUnreachableNLRIAttribute.java
index 32600d9..fdbec22 100644
--- a/src/main/java/com/lumaserv/bgp/protocol/attribute/MPUnreachableNLRIAttribute.java
+++ b/src/main/java/com/lumaserv/bgp/protocol/attribute/MPUnreachableNLRIAttribute.java
@@ -4,9 +4,12 @@ import lombok.Getter;
 import lombok.Setter;
 
 import com.lumaserv.bgp.protocol.AFI;
+import com.lumaserv.bgp.protocol.IPPrefix;
 import com.lumaserv.bgp.protocol.SAFI;
 
 import java.nio.ByteBuffer;
+import java.util.ArrayList;
+import java.util.Collection;
 
 @Getter
 @Setter
@@ -14,12 +17,27 @@ public class MPUnreachableNLRIAttribute implements PathAttribute {
 
     AFI afi;
     SAFI safi;
-    int nlriLen;
+    Collection<IPPrefix> withdrawnPrefixes;
 
     public MPUnreachableNLRIAttribute(byte typeCode, byte[] data) {
         afi = AFI.fromInteger((data[0] << 8) | data[1]);
         safi = SAFI.fromInteger(data[2]);
-        nlriLen = data.length - 3;
+        int nlriLen = data.length - 3;
+
+        withdrawnPrefixes = new ArrayList<>();
+
+        int offset = 3;
+        int offsetOffset = offset;
+        while ((offset - offsetOffset) < nlriLen) {
+            IPPrefix prefix = new IPPrefix()
+                    .setLength((int)(data[offset]&0xff)) // FIXME IPv4/IPv6 etc
+                    .setAddress(new byte[16]);
+            offset++;
+            int addressLen = (int) Math.ceil(prefix.getLength() / 8d);
+            System.arraycopy(data, offset, prefix.getAddress(), 0, addressLen);
+            offset += addressLen;
+            withdrawnPrefixes.add(prefix);
+        }
     }
 
     public byte getTypeCode() {
@@ -32,6 +50,6 @@ public class MPUnreachableNLRIAttribute implements PathAttribute {
     }
 
     public String toString() {
-        return "{AFI:" + afi + " SAFI:" + safi + " NLRIs:" + nlriLen + "}";
+        return "{AFI:" + afi + " SAFI:" + safi + " Withdrawn NLRIs:" + withdrawnPrefixes + "}";
     }
 }