babeld: Initial import, for Babel routing protocol.

* Initial import of the Babel routing protocol, ported to Quagga.
* LICENCE: Update the original LICENCE file to include all known potentially
  applicable copyright claims.  Ask that any future contributors to babeld/
  grant MIT/X11 licence to their work.
* *.{c,h}: Add GPL headers, in according with the SFLC guidance on
  dealing with potentially mixed GPL/other licensed work, at:

  https://www.softwarefreedom.org/resources/2007/gpl-non-gpl-collaboration.html
diff --git a/babeld/message.h b/babeld/message.h
new file mode 100644
index 0000000..1626a88
--- /dev/null
+++ b/babeld/message.h
@@ -0,0 +1,112 @@
+/*  
+ *  This file is free software: you may copy, redistribute and/or modify it  
+ *  under the terms of the GNU General Public License as published by the  
+ *  Free Software Foundation, either version 2 of the License, or (at your  
+ *  option) any later version.  
+ *  
+ *  This file is distributed in the hope that it will be useful, but  
+ *  WITHOUT ANY WARRANTY; without even the implied warranty of  
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU  
+ *  General Public License for more details.  
+ *  
+ *  You should have received a copy of the GNU General Public License  
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.  
+ *  
+ * This file incorporates work covered by the following copyright and  
+ * permission notice:  
+ *  
+Copyright (c) 2007, 2008 by Juliusz Chroboczek
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
+*/
+
+#ifndef BABEL_MESSAGE_H
+#define BABEL_MESSAGE_H
+
+#include "babel_interface.h"
+
+#define MAX_BUFFERED_UPDATES 200
+
+#define BUCKET_TOKENS_MAX 200
+#define BUCKET_TOKENS_PER_SEC 40
+
+#define MESSAGE_PAD1 0
+#define MESSAGE_PADN 1
+#define MESSAGE_ACK_REQ 2
+#define MESSAGE_ACK 3
+#define MESSAGE_HELLO 4
+#define MESSAGE_IHU 5
+#define MESSAGE_ROUTER_ID 6
+#define MESSAGE_NH 7
+#define MESSAGE_UPDATE 8
+#define MESSAGE_REQUEST 9
+#define MESSAGE_MH_REQUEST 10
+
+
+extern unsigned short myseqno;
+extern struct timeval seqno_time;
+
+extern int parasitic;
+extern int broadcast_ihu;
+extern int split_horizon;
+
+extern unsigned char packet_header[4];
+
+extern struct neighbour *unicast_neighbour;
+extern struct timeval unicast_flush_timeout;
+
+void parse_packet(const unsigned char *from, struct interface *ifp,
+                  const unsigned char *packet, int packetlen);
+void flushbuf(struct interface *ifp);
+void flushupdates(struct interface *ifp);
+void send_ack(struct neighbour *neigh, unsigned short nonce,
+              unsigned short interval);
+void send_hello_noupdate(struct interface *ifp, unsigned interval);
+void send_hello(struct interface *ifp);
+void flush_unicast(int dofree);
+void send_update(struct interface *ifp, int urgent,
+                 const unsigned char *prefix, unsigned char plen);
+void send_update_resend(struct interface *ifp,
+                        const unsigned char *prefix, unsigned char plen);
+void send_wildcard_retraction(struct interface *ifp);
+void update_myseqno(void);
+void send_self_update(struct interface *ifp);
+void send_ihu(struct neighbour *neigh, struct interface *ifp);
+void send_marginal_ihu(struct interface *ifp);
+void send_request(struct interface *ifp,
+                  const unsigned char *prefix, unsigned char plen);
+void send_unicast_request(struct neighbour *neigh,
+                          const unsigned char *prefix, unsigned char plen);
+void send_multihop_request(struct interface *ifp,
+                           const unsigned char *prefix, unsigned char plen,
+                           unsigned short seqno, const unsigned char *id,
+                           unsigned short hop_count);
+void
+send_unicast_multihop_request(struct neighbour *neigh,
+                              const unsigned char *prefix, unsigned char plen,
+                              unsigned short seqno, const unsigned char *id,
+                              unsigned short hop_count);
+void send_request_resend(struct neighbour *neigh,
+                         const unsigned char *prefix, unsigned char plen,
+                         unsigned short seqno, unsigned char *id);
+void handle_request(struct neighbour *neigh, const unsigned char *prefix,
+                    unsigned char plen, unsigned char hop_count,
+                    unsigned short seqno, const unsigned char *id);
+
+#endif