diff --git a/babeld/source.h b/babeld/source.h
new file mode 100644
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--- /dev/null
+++ b/babeld/source.h
@@ -0,0 +1,66 @@
+/*  
+ *  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_SOURCE_H
+#define BABEL_SOURCE_H
+
+#define SOURCE_GC_TIME 200
+
+struct source {
+    struct source *next;
+    unsigned char id[8];
+    unsigned char prefix[16];
+    unsigned char plen;
+    unsigned short seqno;
+    unsigned short metric;
+    time_t time;
+};
+
+int source_match(struct source *src,
+                 const unsigned char *p, unsigned char plen);
+struct source *find_source(const unsigned char *id,
+                           const unsigned char *p,
+                           unsigned char plen,
+                           int create, unsigned short seqno);
+int flush_source(struct source *src);
+void update_source(struct source *src,
+                   unsigned short seqno, unsigned short metric);
+void expire_sources(void);
+
+
+#endif