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
50 struct tcl_list*
tcl_list_create(void)51 tcl_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
65 static void
tcl_list_free_node(rbnode_type * node,void * ATTR_UNUSED (arg))66 tcl_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
75 void
tcl_list_delete(struct tcl_list * tcl)76 tcl_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 */
86 static struct tcl_addr*
tcl_list_insert(struct tcl_list * tcl,struct sockaddr_storage * addr,socklen_t addrlen,int net,uint32_t limit,int complain_duplicates)87 tcl_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 */
105 static int
tcl_list_str_cfg(struct tcl_list * tcl,const char * str,const char * s2,int complain_duplicates)106 tcl_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 */
131 static int
read_tcl_list(struct tcl_list * tcl,struct config_file * cfg)132 read_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
143 int
tcl_list_apply_cfg(struct tcl_list * tcl,struct config_file * cfg)144 tcl_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
154 int
tcl_new_connection(struct tcl_addr * tcl)155 tcl_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
170 void
tcl_close_connection(struct tcl_addr * tcl)171 tcl_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
181 struct tcl_addr*
tcl_addr_lookup(struct tcl_list * tcl,struct sockaddr_storage * addr,socklen_t addrlen)182 tcl_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
189 size_t
tcl_list_get_mem(struct tcl_list * tcl)190 tcl_list_get_mem(struct tcl_list* tcl)
191 {
192 if(!tcl) return 0;
193 return sizeof(*tcl) + regional_get_mem(tcl->region);
194 }
195