tcp_conn_limit.h revision 356345 
1/*
2 * daemon/tcp_conn_limit.h - client TCP connection limit storage for the server.
3 *
4 * Copyright (c) 2018, NLnet Labs. All rights reserved.
5 *
6 * This software is open source.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 *
12 * Redistributions of source code must retain the above copyright notice,
13 * this list of conditions and the following disclaimer.
14 *
15 * Redistributions in binary form must reproduce the above copyright notice,
16 * this list of conditions and the following disclaimer in the documentation
17 * and/or other materials provided with the distribution.
18 *
19 * Neither the name of the NLNET LABS nor the names of its contributors may
20 * be used to endorse or promote products derived from this software without
21 * specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
24 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
25 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
26 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
27 * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
28 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
29 * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
30 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
31 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
32 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
33 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
34 */
35
36/**
37 * \file
38 *
39 * This file keeps track of the limit on the number of TCP connections
40 * each client makes the server.
41 */
42
43#ifndef DAEMON_TCP_CONN_LIMIT_H
44#define DAEMON_TCP_CONN_LIMIT_H
45#include "util/storage/dnstree.h"
46#include "util/locks.h"
47struct config_file;
48struct regional;
49
50/**
51 * TCP connection limit storage structure
52 */
53struct tcl_list {
54	/** regional for allocation */
55	struct regional* region;
56	/**
57	 * Tree of the addresses that are TCP connection limited.
58	 * contents of type tcl_addr.
59	 */
60	rbtree_type tree;
61};
62
63/**
64 *
65 * An address span with connection limit information
66 */
67struct tcl_addr {
68	/** node in address tree */
69	struct addr_tree_node node;
70	/** lock on structure data */
71	lock_quick_type lock;
72	/** connection limit on this netblock */
73	uint32_t limit;
74	/** current connection count on this netblock */
75	uint32_t count;
76};
77
78/**
79 * Create TCP connection limit structure
80 * @return new structure or NULL on error.
81 */
82struct tcl_list* tcl_list_create(void);
83
84/**
85 * Delete TCP connection limit structure.
86 * @param tcl: to delete.
87 */
88void tcl_list_delete(struct tcl_list* tcl);
89
90/**
91 * Process TCP connection limit config.
92 * @param tcl: where to store.
93 * @param cfg: config options.
94 * @return 0 on error.
95 */
96int tcl_list_apply_cfg(struct tcl_list* tcl, struct config_file* cfg);
97
98/**
99 * Increment TCP connection count if found, provided the
100 * count was below the limit.
101 * @param tcl: structure for tcl storage, or NULL.
102 * @return: 0 if limit reached, 1 if tcl was NULL or limit not reached.
103 */
104int tcl_new_connection(struct tcl_addr* tcl);
105
106/**
107 * Decrement TCP connection count if found.
108 * @param tcl: structure for tcl storage, or NULL.
109 */
110void tcl_close_connection(struct tcl_addr* tcl);
111
112/**
113 * Lookup address to see its TCP connection limit structure
114 * @param tcl: structure for address storage.
115 * @param addr: address to check
116 * @param addrlen: length of addr.
117 * @return: tcl structure from this address.
118 */
119struct tcl_addr*
120tcl_addr_lookup(struct tcl_list* tcl, struct sockaddr_storage* addr,
121        socklen_t addrlen);
122
123/**
124 * Get memory used by TCP connection limit structure.
125 * @param tcl: structure for address storage.
126 * @return bytes in use.
127 */
128size_t tcl_list_get_mem(struct tcl_list* tcl);
129
130#endif /* DAEMON_TCP_CONN_LIMIT_H */
131