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tcp_conn_limit.h revision 1.1.1.2 
      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"
     47 struct config_file;
     48 struct regional;
     49 
     50 /**
     51  * TCP connection limit storage structure
     52  */
     53 struct 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  */
     67 struct 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  */
     82 struct tcl_list* tcl_list_create(void);
     83 
     84 /**
     85  * Delete TCP connection limit structure.
     86  * @param tcl: to delete.
     87  */
     88 void 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  */
     96 int 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  */
    104 int 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  */
    110 void 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  */
    119 struct tcl_addr*
    120 tcl_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  */
    128 size_t tcl_list_get_mem(struct tcl_list* tcl);
    129 
    130 /**
    131  * Swap internal tree with preallocated entries. Caller should manage
    132  * tcl_addr item locks.
    133  * @param tcl: the tcp connection list structure.
    134  * @param data: the data structure used to take elements from. This contains
    135  * 	the old elements on return.
    136  */
    137 void tcl_list_swap_tree(struct tcl_list* tcl, struct tcl_list* data);
    138 
    139 #endif /* DAEMON_TCP_CONN_LIMIT_H */
    140