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diff --git a/include/inn/hashtab.h b/include/inn/hashtab.h
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+/*  $Id: hashtab.h 5944 2002-12-08 02:33:08Z rra $
+**
+**  Generic hash table interface.
+**
+**  Written by Russ Allbery <rra@stanford.edu>
+**  This work is hereby placed in the public domain by its author.
+**
+**  A hash table takes a hash function that acts on keys, a function to
+**  extract the key from a data item stored in a hash, a function that takes
+**  a key and a data item and returns true if the key matches, and a
+**  function to be called on any data item being deleted from the hash.
+**
+**  hash_create creates a hash and hash_free frees all the space allocated
+**  by one.  hash_insert, hash_replace, and hash_delete modify it, and
+**  hash_lookup extracts values.  hash_traverse can be used to walk the
+**  hash, and hash_count returns the number of elements currently stored in
+**  the hash.  hash_searches, hash_collisions, and hash_expansions extract
+**  performance and debugging statistics.
+*/
+
+#ifndef INN_HASHTAB_H
+#define INN_HASHTAB_H 1
+
+#include <inn/defines.h>
+
+BEGIN_DECLS
+
+/* The layout of this struct is entirely internal to the implementation. */
+struct hash;
+
+/* Data types for function pointers used by the hash table interface. */
+typedef unsigned long (*hash_func)(const void *);
+typedef const void * (*hash_key_func)(const void *);
+typedef bool (*hash_equal_func)(const void *, const void *);
+typedef void (*hash_delete_func)(void *);
+typedef void (*hash_traverse_func)(void *, void *);
+
+/* Generic hash table interface. */
+struct hash *   hash_create(size_t, hash_func, hash_key_func,
+                            hash_equal_func, hash_delete_func);
+void            hash_free(struct hash *);
+void *          hash_lookup(struct hash *, const void *key);
+bool            hash_insert(struct hash *, const void *key, void *datum);
+bool            hash_replace(struct hash *, const void *key, void *datum);
+bool            hash_delete(struct hash *, const void *key);
+void            hash_traverse(struct hash *, hash_traverse_func, void *);
+unsigned long   hash_count(struct hash *);
+unsigned long   hash_searches(struct hash *);
+unsigned long   hash_collisions(struct hash *);
+unsigned long   hash_expansions(struct hash *);
+
+/* Hash functions available for callers. */
+unsigned long   hash_string(const void *);
+
+/* Functions useful for constructing new hashes. */
+unsigned long   hash_lookup2(const char *, size_t, unsigned long partial);
+
+END_DECLS
+
+#endif /* INN_HASHTAB_H */