Implementation of the users table and a generic hashtable mechanism

core/depend.mk

@@ -408,7 +408,7 @@ users.o: users.c /usr/include/stdlib.h /usr/include/features.h \
  /usr/include/bits/sigset.h /usr/include/bits/time.h \
  /usr/include/sys/sysmacros.h /usr/include/bits/pthreadtypes.h \
  /usr/include/alloca.h /usr/include/string.h /usr/include/xlocale.h \
- ../include/users.h ../include/hashtable.h
+ ../include/users.h ../include/hashtable.h ../include/atomic.h
 hashtable.o: hashtable.c /usr/include/stdlib.h /usr/include/features.h \
  /usr/include/sys/cdefs.h /usr/include/bits/wordsize.h \
  /usr/include/gnu/stubs.h /usr/include/gnu/stubs-64.h \

core/hashtable.c

@@ -31,9 +31,22 @@
  * @endverbatim
  */
 
+/**
+ * Special null function used as default memory allfunctions in the hashtable
+ * implementation. This avoids havign to special case the code that manipulates
+ * the keys and values
+ *
+ * @param	data	The data pointer
+ * @return	Return the value we were called with
+ */
+static void *
+nullfn(void *data)
+{
+	return data;
+}
 
 /**
- * Allocate a new users table
+ * Allocate a new hash table
  *
  * @param size		The size of the hash table
  * @param hashfn	The user supplied hash function
@@ -50,6 +63,8 @@ HASHTABLE 	*rval;
 	rval->hashsize = size;
 	rval->hashfn = hashfn;
 	rval->cmpfn = cmpfn;
+	rval->copyfn = nullfn;
+	rval->freefn = nullfn;
 	if ((rval->entries = calloc(size, sizeof(HASHENTRIES))) == NULL)
 	{
 		free(rval);
@@ -60,3 +75,183 @@ HASHTABLE 	*rval;
 	return rval;
 }
 
+/**
+ * Delete an entire hash table
+ *
+ * @param	table	The hash table to delete
+ */
+void
+hashtable_free(HASHTABLE *table)
+{
+int		i;
+HASHENTRIES	*entry, *ptr;
+
+	for (i = 0; i < table->hashsize; i++)
+	{
+		entry = table->entries[i];
+		if (entry->key)
+		{
+			table->freefn(entry->key);
+			table->freefn(entry->value);
+		}
+		entry = entry->next;
+		while (entry)
+		{
+			ptr = entry->next;
+			table->freefn(entry->key);
+			table->freefn(entry->value);
+			free(entry);
+			entry = ptr;
+		}
+	}
+	free(table->entries);
+	free(table);
+}
+
+/**
+ * Provide memory management functions to the hash table. This allows
+ * function pointers to be registered that can make copies of the
+ * key and value.
+ *
+ * @param table		The hash table
+ * @param copyfn	The copy function
+ * @param freefn	The free function
+ */
+void
+hashtable_memory_fns(HASHTABLE *table, HASHMEMORYFN copyfn, HASHMEMORYFN freefn)
+{
+	table->copyfn = copyfn;
+	table->freefn = freefn;
+}
+
+/**
+ * Add an item to the hash table.
+ *
+ * @param table		The hash table to which to add the item
+ * @param key		The key of the item
+ * @param value		The value for the item
+ * @return	Return the number of items added
+ */
+int
+hashtable_add(HASHTABLE *table, void *key, void *value)
+{
+int		hashkey = table->hashfn(key);
+HASHENTRIES	*entry;
+
+	entry = table->entries[hashkey % table->hashsize];
+	while (entry->next && entry->key && table->cmpfn(key, entry->key) != 0)
+	{
+		entry = entry->next;
+	}
+	if (entry->key == NULL)
+	{
+		/* Entry is empty - special case for first insert */
+		entry->key = table->copyfn(key);
+		entry->value = table->copyfn(value);
+	}
+	else if (table->cmpfn(key, entry->key) == 0)
+	{
+		/* Duplicate key value */
+		return 0;
+	}
+	else
+	{
+		HASHENTRIES	*ptr = (HASHENTRIES *)malloc(sizeof(HASHENTRIES));
+		if (ptr == NULL)
+			return 0;
+		ptr->key = table->copyfn(key);
+		ptr->value = table->copyfn(value);
+		ptr->next = NULL;
+		entry->next = ptr;
+	}
+	return 1;
+}
+
+/**
+ * Delete an item from the hash table that has a given key
+ *
+ * @param table		The hash table to delete from
+ * @param key		The key value of the item to remove
+ * @return Return the number of items deleted
+ */
+int
+hashtable_delete(HASHTABLE *table, void *key)
+{
+int		hashkey = table->hashfn(key);
+HASHENTRIES	*entry, *ptr;
+
+	entry = table->entries[hashkey % table->hashsize];
+	while (entry && entry->key && table->cmpfn(key, entry->key) != 0)
+	{
+		entry = entry->next;
+	}
+	if (entry == NULL || entry->key == NULL)
+	{
+		/* Not found */
+		return 0;
+	}
+
+	if (entry == table->entries[hashkey % table->hashsize])
+	{
+		/* We are removing from the special first entry */
+		if (entry->next)
+		{
+			table->freefn(entry->key);
+			table->freefn(entry->value);
+			entry->key = entry->next->key;
+			entry->value = entry->next->value;
+			ptr = entry->next;
+			entry->next = ptr->next;
+			free(ptr);
+		}
+		else
+		{
+			table->freefn(entry->key);
+			table->freefn(entry->value);
+			entry->key = NULL;
+			entry->value = NULL;
+		}
+	}
+	else
+	{
+		ptr = table->entries[hashkey % table->hashsize];
+		while (ptr && ptr->next != entry)
+			ptr = ptr->next;
+		if (ptr == NULL)
+			return 0;	/* This should never happen */
+		ptr->next = entry->next;
+		table->freefn(entry->key);
+		table->freefn(entry->value);
+		free(entry);
+	}
+	return 1;
+}
+
+/**
+ * Fetch an item with a given key value from the hash table
+ *
+ * @param table		The hash table
+ * @param key		The key value
+ * @return The item or NULL if the item was not found
+ */
+void *
+hashtable_fetch(HASHTABLE *table, void *key)
+{
+int		hashkey = table->hashfn(key);
+HASHENTRIES	*entry;
+
+	entry = table->entries[hashkey % table->hashsize];
+	while (entry && entry->key && table->cmpfn(key, entry->key) != 0)
+	{
+		entry = entry->next;
+	}
+	if (entry == NULL || entry->key == NULL)
+	{
+		return NULL;
+	}
+	else
+	{
+		return entry->value;
+	}
+}
+

core/service.c

@@ -70,7 +70,7 @@ SERVICE 	*service;
 	service->state = SERVICE_STATE_ALLOC;
 	service->credentials.name = NULL;
 	service->credentials.authdata = NULL;
-	service->users = NULL;
+	service->users = users_alloc();
 
 	spinlock_acquire(&service_spin);
 	service->next = allServices;

core/users.c

@@ -18,6 +18,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <users.h>
+#include <atomic.h>
 
 /**
  * @file users.c User table maintenance routines
@@ -40,7 +41,7 @@
 static int
 user_hash(char *key)
 {
-	return (*key + *(key + 1)) % 52;
+	return (*key + *(key + 1));
 }
 
 /**
@@ -62,6 +63,70 @@ USERS 	*rval;
 		return NULL;
 	}
 
+	hashtable_memory_fns(rval->data, (HASHMEMORYFN)strdup, (HASHMEMORYFN)free);
+
 	return rval;
 }
 
+/**
+ * Remove the users table
+ *
+ * @param users	The users table to remove
+ */
+void
+users_free(USERS *users)
+{
+	hashtable_free(users->data);
+	free(users);
+}
+
+/**
+ * Add a new user to the user table. The user name must be unique
+ *
+ * @param users		The users table
+ * @param user		The user name
+ * @param auth		The authentication data
+ * @return	The number of users added to the table
+ */
+int
+users_add(USERS *users, char *user, char *auth)
+{
+int	add;
+
+	atomic_add(&users->stats.n_adds, 1);
+	add = hashtable_add(users->data, user, auth);
+	atomic_add(&users->stats.n_entries, add);
+	return add;
+}
+
+/**
+ * Delete a user from the user table.
+ *
+ * @param users		The users table
+ * @param user		The user name
+ * @return	The number of users deleted from the table
+ */
+int
+users_delete(USERS *users, char *user)
+{
+int	del;
+
+	atomic_add(&users->stats.n_deletes, 1);
+	del = hashtable_delete(users->data, user);
+	atomic_add(&users->stats.n_entries, del * -1);
+	return del;
+}
+
+/**
+ * Fetch the authentication data for a particular user from the users table
+ *
+ * @param users		The users table
+ * @param user		The user name
+ * @return	The authentication data or NULL on error
+ */
+char
+*users_fetch(USERS *users, char *user)  
+{
+	atomic_add(&users->stats.n_fetches, 1);
+	return hashtable_fetch(users->data, user);
+}

include/hashtable.h

@@ -38,25 +38,38 @@
  * The next pointer is the overflow chain for this hashentry.
  */
 typedef struct hashentry {
-	void			*key;		/**< The value of the key or NULL if empty entry */
+	void			*key;	/**< The value of the key or NULL if empty entry */
-	void			*value;		/**< The value associated with key */
+	void			*value;	/**< The value associated with key */
-	struct	hashentry	*next;		/**< The overflow chain */
+	struct	hashentry	*next;	/**< The overflow chain */
 } HASHENTRIES;
 
+/**
+ * The type definition for the memory allocation functions
+ */
+typedef void *(*HASHMEMORYFN)(void *);
+
 /**
  * The general purpose hashtable struct.
  */
 typedef struct hashtable {
 	int		hashsize;			/**< The number of HASHENTRIES */
-	HASHENTRIES	*entries;			/**< The entries themselves */
+	HASHENTRIES	**entries;			/**< The entries themselves */
 	int		(*hashfn)(void *);		/**< The hash function */
 	int		(*cmpfn)(void *, void *);	/**< The key comparison function */
+	HASHMEMORYFN	copyfn;				/**< Optional copy function */
+	HASHMEMORYFN	freefn;				/**< Optional free function */
 } HASHTABLE;
 
-extern HASHTABLE	*hashtable_alloc(int, int (*hashfn)(),
+extern HASHTABLE	*hashtable_alloc(int, int (*hashfn)(), int (*cmpfn)());
-					 int (*cmpfn)());		/**< Allocate a hashtable */
+				/**< Allocate a hashtable */
+extern void		hashtable_memory_fns(HASHTABLE *, HASHMEMORYFN, HASHMEMORYFN);
+				/**< Provide an interface to control key/value memory
+				 * manipulation
+				 */
 extern void		hashtable_free(HASHTABLE *);			/**< Free a hashtable */
-extern int		hashtable_add(HASHTABLE *, char *, void *);	/**< Add an entry */
+extern int		hashtable_add(HASHTABLE *, void *, void *);	/**< Add an entry */
-extern int		hashtable_delete(HASHTABLE *, char *);		/**< Delete an entry table */
+extern int		hashtable_delete(HASHTABLE *, void *);
-extern void		*hashtable_fetch(HASHTABLE *, char *);		/**< Fetch the data for a given key */
+				/**< Delete an entry table */
+extern void		*hashtable_fetch(HASHTABLE *, void *);
+				/**< Fetch the data for a given key */
 #endif

include/users.h

@@ -31,12 +31,26 @@
  * @endverbatim
  */
 
+/**
+ * The users table statistics structure
+ */
+typedef struct {
+	int	n_entries;		/**< The number of entries */
+	int	n_adds;			/**< The number of inserts */
+	int	n_deletes;		/**< The number of deletes */
+	int	n_fetches;		/**< The number of fetchs */
+} USERS_STATS;
+/**
+ * The user table, this contains the username and authentication data required
+ * for the authentication implementation within the gateway.
+ */
 typedef struct users {
-	HASHTABLE	*data;
+	HASHTABLE	*data;		/**< The hashtable containing the actual data */
+	USERS_STATS	stats;		/**< The statistics for the users table */
 } USERS;
 
 extern USERS	*users_alloc();				/**< Allocate a users table */
-extern		users_free(USERS *);			/**< Free a users table */
+extern void	users_free(USERS *);			/**< Free a users table */
 extern int	users_add(USERS *, char *, char *);	/**< Add a user to the users table */
 extern int	users_delete(USERS *, char *);		/**< Delete a user from the users table */
 extern char	*users_fetch(USERS *, char *);		/**< Fetch the authentication data for a user */