1 /* -------------------------------------------------------------------------
2 * libtcp-portmon.h: tcp port monitoring library.
4 * Copyright (C) 2005 Philip Kovacs kovacsp3@comcast.net
8 * This library is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation; either
11 * version 2.1 of the License, or (at your option) any later version.
13 * This library is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * Lesser General Public License for more details.
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with this library; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
21 * --------------------------------------------------------------------------- */
23 #ifndef LIBTCP_PORTMON_H
24 #define LIBTCP_PORTMON_H
26 #include <sys/socket.h>
28 #include <arpa/inet.h>
29 #include <netinet/in.h>
30 #include <netinet/tcp.h>
40 /* ------------------------------------------------------------------------------------------------
41 * Each port monitor contains a connection hash whose contents changes dynamically as the monitor
42 * is presented with connections on each update cycle. This implementation maintains the health
43 * of this hash by enforcing several rules. First, the hash cannot contain more items than the
44 * TCP_CONNECTION_HASH_MAX_LOAD_RATIO permits. For example, a 512 element hash with a max load of
45 * 0.5 cannot contain more than 256 connections. Additional connections are ignored by the monitor.
46 * The load factor of 0.5 is low enough to keep the hash running at near O(1) performanace at all
47 * times. As elements are removed from the hash, the hash slots are tagged vacated, as required
48 * by open address hashing. The vacated tags are essential as they enable the hash to find elements
49 * for which there were collisions during insert (requiring additional probing for an open slot).
50 * The problem with vacated slots (even though they are reused) is that, as they increase in number,
51 * esp. past about 1/4 of all slots, the average number of probes the hash has to perform increases
52 * from O(1) on average to O(n) worst case. To keep the hash healthy, we simply rebuild it when the
53 * percentage of vacated slots gets too high (above TCP_CONNECTION_HASH_MAX_VACATED_RATIO).
54 * Rebuilding the hash takes O(n) on the number of elements, but it well worth it as it keeps the
55 * hash running at an average access time of O(1).
56 * ------------------------------------------------------------------------------------------------*/
58 #define TCP_CONNECTION_HASH_SIZE_DEFAULT 512 /* connection hash size default -- must be a power of two */
59 #define TCP_CONNECTION_HASH_SIZE_MAX 65536 /* connection hash size maximum -- must be a power of two */
60 #define TCP_CONNECTION_HASH_MAX_LOAD_RATIO 0.5 /* disallow inserts after this load ratio is exceeded */
61 #define TCP_CONNECTION_HASH_MAX_VACATED_RATIO 0.25 /* rebalance hash after this ratio of vacated slots is exceeded */
62 #define TCP_CONNECTION_STARTING_AGE 1 /* connection deleted if unseen again after this # of refreshes */
64 /* ----------------------------------------------------------------------------------------
65 * The tcp port monitor collection also contains a hash to track the monitors it contains.
66 * This hash, unlike the connection hash describes above, is not very dynamic. Clients of
67 * this library typically create a fixed number of monitors and let them run until program
68 * termination. For this reason, I haven't included any hash rebuilding code as is done
69 * above. You may store up to TCP_MONITOR_HASH_SIZE_MAX monitors in this hash, but you
70 * should remember that keeping the load low (e.g. 0.5) keeps the monitor lookups at O(1).
71 * ----------------------------------------------------------------------------------------*/
73 #define TCP_MONITOR_HASH_SIZE_DEFAULT 32 /* monitor hash size default -- must be a power of two */
74 #define TCP_MONITOR_HASH_SIZE_MAX 512 /* monitor hash size maximum -- must be a power of two */
75 #define TCP_MONITOR_HASH_MAX_LOAD_RATIO 0.5 /* disallow new monitors after this load ratio is exceeded */
77 /* -------------------------------------------------------------------
78 * IMPLEMENTATION INTERFACE
80 * Implementation-specific interface begins here. Clients should not
81 * manipulate these structures directly, nor call the defined helper
82 * functions. Use the "Client interface" functions defined at bottom.
83 * ------------------------------------------------------------------- */
85 /* The inventory of peekable items within the port monitor. */
86 enum tcp_port_monitor_peekables { COUNT=0, REMOTEIP, REMOTEHOST, REMOTEPORT, LOCALIP, LOCALHOST, LOCALPORT, LOCALSERVICE };
88 /* ------------------------------------------------------------------------
89 * A single tcp connection
91 * The age variable provides the mechanism for removing connections if they
92 * are not seen again in subsequent update cycles.
93 * ------------------------------------------------------------------------ */
94 typedef struct _tcp_connection_t {
97 in_addr_t remote_addr;
98 in_port_t remote_port;
102 /* ----------------------------------
105 * Returns 0 on success, -1 otherwise
106 * ----------------------------------*/
107 int copy_tcp_connection(
108 tcp_connection_t * /* p_dest_connection */,
109 const tcp_connection_t * /* p_source_connection */
112 /* ------------------------------------------------------------------------
113 * A tcp connection node/list
115 * Connections within each monitor are stored in a double-linked list.
116 * ------------------------------------------------------------------------ */
117 typedef struct _tcp_connection_node_t {
118 tcp_connection_t connection;
119 struct _tcp_connection_node_t * p_prev;
120 struct _tcp_connection_node_t * p_next;
121 } tcp_connection_node_t;
123 typedef struct _tcp_connection_list_t {
124 tcp_connection_node_t * p_head;
125 tcp_connection_node_t * p_tail;
126 } tcp_connection_list_t;
131 typedef struct _tcp_port_monitor_t {
132 in_port_t port_range_begin;
133 in_port_t port_range_end; /* begin = end to monitor a single port */
134 tcp_connection_list_t connection_list; /* list of connections for this monitor */
135 hash_table_t hash; /* hash table contains pointers into monitor's connection list */
136 tcp_connection_t **p_peek; /* array of connection pointers for O(1) peeking by index */
137 } tcp_port_monitor_t;
139 /* -----------------------------------------------------------------------------
140 * Open-addressed hash implementation requires that we supply two hash functions
141 * and a match function to compare two hash elements for identity.
142 * ----------------------------------------------------------------------------- */
144 /* --------------------------------------------------
145 * Functions to hash the connections within a monitor
146 * --------------------------------------------------*/
148 /* First connection hash function */
149 int connection_hash_function_1( const void * /* p_data */ );
151 /* Second connection hash function */
152 int connection_hash_function_2( const void * /* p_data */ );
154 /* Connection match function returns non-zero if hash elements are identical. */
155 int connection_match_function( const void * /* p_data1 */, const void * /* p_data2 */ );
157 /* --------------------------------------------------
158 * Functions to hash the monitors within a collection
159 * --------------------------------------------------*/
161 /* First monitor hash function */
162 int monitor_hash_function_1( const void * /* p_data */ );
164 /* Second monitor hash function */
165 int monitor_hash_function_2( const void * /* p_data */ );
167 /* Monitor match function returns non-zero if hash elements are identical. */
168 int monitor_match_function( const void * /* p_data1 */, const void * /* p_data2 */ );
170 /* ------------------------
171 * A port monitor node/list
172 * ------------------------ */
173 typedef struct _tcp_port_monitor_node_t {
174 tcp_port_monitor_t * p_monitor;
175 struct _tcp_port_monitor_node_t *p_next;
176 } tcp_port_monitor_node_t;
178 typedef struct __tcp_port_monitor_list_t {
179 tcp_port_monitor_node_t * p_head;
180 tcp_port_monitor_node_t * p_tail;
181 } tcp_port_monitor_list_t;
183 /* ---------------------------------------
184 * A port monitor utility function typedef
185 * ---------------------------------------*/
186 typedef void (*tcp_port_monitor_function_ptr_t)( tcp_port_monitor_t * /* p_monitor */, void * /* p_void */ );
188 /* ---------------------------------------------------------------------------
189 * Port monitor utility functions implementing tcp_port_monitor_function_ptr_t
190 * ---------------------------------------------------------------------------*/
191 void destroy_tcp_port_monitor(
192 tcp_port_monitor_t * /* p_monitor */,
193 void * /* p_void (use NULL for this function) */
196 void age_tcp_port_monitor(
197 tcp_port_monitor_t * /* p_monitor */,
198 void * /* p_void (use NULL for this function) */
201 void maintain_tcp_port_monitor_hash(
202 tcp_port_monitor_t * /* p_monitor */,
203 void * /* p_void (use NULL for this function) */
206 void rebuild_tcp_port_monitor_peek_table(
207 tcp_port_monitor_t * /* p_monitor */,
208 void * /* p_void (use NULL for this function) */
211 void show_connection_to_tcp_port_monitor(
212 tcp_port_monitor_t * /* p_monitor */,
213 void * /* p_connection (client should cast) */
216 /* -----------------------------
217 * A tcp port monitor collection
218 * -----------------------------*/
219 typedef struct _tcp_port_monitor_collection_t {
220 tcp_port_monitor_list_t monitor_list; /* list of monitors for this collection */
221 hash_table_t hash; /* hash table contains pointers into collection's monitor list */
222 } tcp_port_monitor_collection_t;
224 /* ---------------------------------------------------------------------------------------
225 * Apply a tcp_port_monitor_function_ptr_t function to each port monitor in the collection.
226 * ---------------------------------------------------------------------------------------*/
227 void for_each_tcp_port_monitor_in_collection(
228 tcp_port_monitor_collection_t * /* p_collection */,
229 tcp_port_monitor_function_ptr_t /* p_function */,
230 void * /* p_function_args (for user arguments) */
233 /* ----------------------------------------------------------------------------------------
234 * Calculate an efficient hash size based on the desired number of elements and load factor.
235 * ---------------------------------------------------------------------------------------- */
236 int calc_efficient_hash_size(
237 int /* min_elements, the minimum number of elements to store */,
238 int /* max_hash_size, the maximum permissible hash size */,
239 double /* max_load_factor, the fractional load we wish not to exceed, e.g. 0.5 */
242 /* ----------------------------------------------------------------------
245 * Clients should call only those functions below this line.
246 * ---------------------------------------------------------------------- */
248 /* struct to hold monitor creation arguments */
249 typedef struct _tcp_port_monitor_args_t {
250 int min_port_monitor_connections; /* monitor must support tracking at least this many connections */
251 } tcp_port_monitor_args_t;
254 /* struct to hold collection creation arguments */
255 typedef struct _tcp_port_monitor_collection_args_t {
256 int min_port_monitors; /* collection must support creation of at least this many monitors */
257 } tcp_port_monitor_collection_args_t;
259 /* ----------------------------------
260 * Client operations on port monitors
261 * ---------------------------------- */
263 /* Clients should first try to "find_tcp_port_monitor" before creating one
264 so that there are no redundant monitors. */
265 tcp_port_monitor_t * create_tcp_port_monitor(
266 in_port_t /* port_range_begin */,
267 in_port_t /* port_range_end */,
268 tcp_port_monitor_args_t * /* p_creation_args, NULL ok for library defaults */
271 /* Clients use this function to get connection data from the indicated port monitor.
272 The requested monitor value is copied into a client-supplied char buffer.
273 Returns 0 on success, -1 otherwise. */
274 int peek_tcp_port_monitor(
275 const tcp_port_monitor_t * /* p_monitor */,
276 int /* item, ( item of interest, from tcp_port_monitor_peekables enum ) */,
277 int /* connection_index, ( 0 to number of connections in monitor - 1 )*/,
278 char * /* p_buffer, buffer to receive requested value */,
279 size_t /* buffer_size, size of p_buffer */
282 /* --------------------------------
283 * Client operations on collections
284 * -------------------------------- */
286 /* Create a monitor collection. Do this one first. */
287 tcp_port_monitor_collection_t * create_tcp_port_monitor_collection(
288 tcp_port_monitor_collection_args_t * /* p_creation_args, NULL ok for library defaults */
291 /* Destroy the monitor collection (and everything it contains). Do this one last. */
292 void destroy_tcp_port_monitor_collection(
293 tcp_port_monitor_collection_t * /* p_collection */
296 /* Updates the tcp statitics for all monitors within a collection */
297 void update_tcp_port_monitor_collection(
298 tcp_port_monitor_collection_t * /* p_collection */
301 /* After clients create a monitor, use this to add it to the collection.
302 Returns 0 on success, -1 otherwise. */
303 int insert_tcp_port_monitor_into_collection(
304 tcp_port_monitor_collection_t * /* p_collection */,
305 tcp_port_monitor_t * /* p_monitor */
308 /* Clients need a way to find monitors */
309 tcp_port_monitor_t * find_tcp_port_monitor(
310 const tcp_port_monitor_collection_t * /* p_collection */,
311 in_port_t /* port_range_begin */,
312 in_port_t /* port_range_end */