tcp_conn_limit.c revision 356345 
1/*
2 * daemon/tcp_conn_limit.c - 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 helps the server discard excess TCP connections.
40 */
41#include "config.h"
42#include "util/regional.h"
43#include "util/log.h"
44#include "util/config_file.h"
45#include "util/net_help.h"
46#include "util/tcp_conn_limit.h"
47#include "services/localzone.h"
48#include "sldns/str2wire.h"
49
50struct tcl_list*
51tcl_list_create(void)
52{
53	struct tcl_list* tcl = (struct tcl_list*)calloc(1,
54		sizeof(struct tcl_list));
55	if(!tcl)
56		return NULL;
57	tcl->region = regional_create();
58	if(!tcl->region) {
59		tcl_list_delete(tcl);
60		return NULL;
61	}
62	return tcl;
63}
64
65static void
66tcl_list_free_node(rbnode_type* node, void* ATTR_UNUSED(arg))
67{
68	struct tcl_addr* n = (struct tcl_addr*) node;
69	lock_quick_destroy(&n->lock);
70#ifdef THREADS_DISABLED
71	(void)n;
72#endif
73}
74
75void
76tcl_list_delete(struct tcl_list* tcl)
77{
78	if(!tcl)
79		return;
80	traverse_postorder(&tcl->tree, tcl_list_free_node, NULL);
81	regional_destroy(tcl->region);
82	free(tcl);
83}
84
85/** insert new address into tcl_list structure */
86static struct tcl_addr*
87tcl_list_insert(struct tcl_list* tcl, struct sockaddr_storage* addr,
88	socklen_t addrlen, int net, uint32_t limit,
89	int complain_duplicates)
90{
91	struct tcl_addr* node = regional_alloc_zero(tcl->region,
92		sizeof(struct tcl_addr));
93	if(!node)
94		return NULL;
95	lock_quick_init(&node->lock);
96	node->limit = limit;
97	if(!addr_tree_insert(&tcl->tree, &node->node, addr, addrlen, net)) {
98		if(complain_duplicates)
99			verbose(VERB_QUERY, "duplicate tcl address ignored.");
100	}
101	return node;
102}
103
104/** apply tcl_list string */
105static int
106tcl_list_str_cfg(struct tcl_list* tcl, const char* str, const char* s2,
107	int complain_duplicates)
108{
109	struct sockaddr_storage addr;
110	int net;
111	socklen_t addrlen;
112	uint32_t limit;
113	if(atoi(s2) < 0) {
114		log_err("bad connection limit %s", s2);
115		return 0;
116	}
117	limit = (uint32_t)atoi(s2);
118	if(!netblockstrtoaddr(str, UNBOUND_DNS_PORT, &addr, &addrlen, &net)) {
119		log_err("cannot parse connection limit netblock: %s", str);
120		return 0;
121	}
122	if(!tcl_list_insert(tcl, &addr, addrlen, net, limit,
123		complain_duplicates)) {
124		log_err("out of memory");
125		return 0;
126	}
127	return 1;
128}
129
130/** read tcl_list config */
131static int
132read_tcl_list(struct tcl_list* tcl, struct config_file* cfg)
133{
134	struct config_str2list* p;
135	for(p = cfg->tcp_connection_limits; p; p = p->next) {
136		log_assert(p->str && p->str2);
137		if(!tcl_list_str_cfg(tcl, p->str, p->str2, 1))
138			return 0;
139	}
140	return 1;
141}
142
143int
144tcl_list_apply_cfg(struct tcl_list* tcl, struct config_file* cfg)
145{
146	regional_free_all(tcl->region);
147	addr_tree_init(&tcl->tree);
148	if(!read_tcl_list(tcl, cfg))
149		return 0;
150	addr_tree_init_parents(&tcl->tree);
151	return 1;
152}
153
154int
155tcl_new_connection(struct tcl_addr* tcl)
156{
157	if(tcl) {
158		int res = 1;
159		lock_quick_lock(&tcl->lock);
160		if(tcl->count >= tcl->limit)
161			res = 0;
162		else
163			tcl->count++;
164		lock_quick_unlock(&tcl->lock);
165		return res;
166	}
167	return 1;
168}
169
170void
171tcl_close_connection(struct tcl_addr* tcl)
172{
173	if(tcl) {
174		lock_quick_lock(&tcl->lock);
175		log_assert(tcl->count > 0);
176		tcl->count--;
177		lock_quick_unlock(&tcl->lock);
178	}
179}
180
181struct tcl_addr*
182tcl_addr_lookup(struct tcl_list* tcl, struct sockaddr_storage* addr,
183        socklen_t addrlen)
184{
185	return (struct tcl_addr*)addr_tree_lookup(&tcl->tree,
186		addr, addrlen);
187}
188
189size_t
190tcl_list_get_mem(struct tcl_list* tcl)
191{
192	if(!tcl) return 0;
193	return sizeof(*tcl) + regional_get_mem(tcl->region);
194}
195