1 files changed, 76 insertions, 0 deletions
diff --git a/src/main/java/com/lumaserv/bgp/protocol/BGPPacket.java b/src/main/java/com/lumaserv/bgp/protocol/BGPPacket.java
new file mode 100644
index 0000000..e7cf66b
--- /dev/null
+++ b/src/main/java/com/lumaserv/bgp/protocol/BGPPacket.java
@@ -0,0 +1,76 @@
+package com.lumaserv.bgp.protocol;
+
+import lombok.AllArgsConstructor;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+import lombok.Setter;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.Arrays;
+
+@Setter
+@Getter
+@NoArgsConstructor
+public class BGPPacket {
+
+    Type type;
+    byte[] message;
+
+    public BGPPacket(byte[] packet) {
+        type = Type.fromValue(packet[18]);
+        message = new byte[packet.length-19];
+        System.arraycopy(packet, 19, message, 0, message.length);
+    }
+
+    public byte[] build() {
+        byte[] packet = new byte[message.length + 19];
+        Arrays.fill(packet, 0, 16, (byte) 0xFF);
+        packet[16] = (byte)(packet.length >> 8);
+        packet[17] = (byte)(packet.length & 0xFF);
+        packet[18] = type.getValue();
+        System.arraycopy(message, 0, packet, 19, message.length);
+        return packet;
+    }
+
+    public static BGPPacket read(InputStream stream) throws IOException {
+        byte[] packet = new byte[18];
+        int value;
+        for(int i=0; i<packet.length; i++) {
+            value = stream.read();
+            if(value == -1)
+                throw new IOException("Unexpected end of stream");
+            packet[i] = (byte) value;
+        }
+        int length = ((packet[16] & 0xFF) << 8) | (packet[17] & 0xFF);
+        byte[] newPacket = new byte[length];
+        System.arraycopy(packet, 0, newPacket, 0, packet.length);
+        packet = newPacket;
+        for(int i=18; i<packet.length; i++) {
+            value = stream.read();
+            if(value == -1)
+                throw new IOException("Unexpected end of stream");
+            packet[i] = (byte) value;
+        }
+        return new BGPPacket(packet);
+    }
+
+    @AllArgsConstructor
+    @Getter
+    public enum Type {
+        OPEN((byte) 1),
+        UPDATE((byte) 2),
+        NOTIFICATION((byte) 3),
+        KEEPALIVE((byte) 4),
+        ROUTE_REFRESH((byte) 5);
+        final byte value;
+        public static Type fromValue(byte value) {
+            for(Type t : values()) {
+                if(t.value == value)
+                    return t;
+            }
+            return null;
+        }
+    }
+
+}