/*

 * daemon/tcp_conn_limit.c - client TCP connection limit storage for the server.

 *

 * Copyright (c) 2018, NLnet Labs. All rights reserved.

 *

 * This software is open source.

 * 

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 * 

 * Redistributions of source code must retain the above copyright notice,

 * this list of conditions and the following disclaimer.

 * 

 * Redistributions in binary form must reproduce the above copyright notice,

 * this list of conditions and the following disclaimer in the documentation

 * and/or other materials provided with the distribution.

 * 

 * Neither the name of the NLNET LABS nor the names of its contributors may

 * be used to endorse or promote products derived from this software without

 * specific prior written permission.

 * 

 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR

 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT

 * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED

 * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR

 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF

 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING

 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS

 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */

/**

 * \file

 *

 * This file helps the server discard excess TCP connections.

 */

#include "config.h"

#include "util/regional.h"

#include "util/log.h"

#include "util/config_file.h"

#include "util/net_help.h"

#include "util/tcp_conn_limit.h"

#include "services/localzone.h"

#include "sldns/str2wire.h"

struct tcl_list*

tcl_list_create(void)

{

  struct tcl_list* tcl = (struct tcl_list*)calloc(1,

    sizeof(struct tcl_list));

  if(!tcl)

    return NULL;

  tcl->region = regional_create();

  if(!tcl->region) {

    tcl_list_delete(tcl);

    return NULL;

  }

  return tcl;

}

static void

tcl_list_free_node(rbnode_type* node, void* ATTR_UNUSED(arg))

{

  struct tcl_addr* n = (struct tcl_addr*) node;

  lock_quick_destroy(&n->lock);

#ifdef THREADS_DISABLED

  (void)n;

#endif

}

void

tcl_list_delete(struct tcl_list* tcl)

{

  if(!tcl)

    return;

  traverse_postorder(&tcl->tree, tcl_list_free_node, NULL);

  regional_destroy(tcl->region);

  free(tcl);

}

/** insert new address into tcl_list structure */

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)

{

  struct tcl_addr* node = regional_alloc_zero(tcl->region,

    sizeof(struct tcl_addr));

  if(!node)

    return NULL;

  lock_quick_init(&node->lock);

  node->limit = limit;

  if(!addr_tree_insert(&tcl->tree, &node->node, addr, addrlen, net)) {

    if(complain_duplicates)

      verbose(VERB_QUERY, "duplicate tcl address ignored.");

  }

  return node;

}

/** apply tcl_list string */

static int

tcl_list_str_cfg(struct tcl_list* tcl, const char* str, const char* s2,

  int complain_duplicates)

{

  struct sockaddr_storage addr;

  int net;

  socklen_t addrlen;

  uint32_t limit;

  if(atoi(s2) < 0) {

    log_err("bad connection limit %s", s2);

    return 0;

  }

  limit = (uint32_t)atoi(s2);

  if(!netblockstrtoaddr(str, UNBOUND_DNS_PORT, &addr, &addrlen, &net)) {

    log_err("cannot parse connection limit netblock: %s", str);

    return 0;

  }

  if(!tcl_list_insert(tcl, &addr, addrlen, net, limit,

    complain_duplicates)) {

    log_err("out of memory");

    return 0;

  }

  return 1;

}

/** read tcl_list config */

static int

read_tcl_list(struct tcl_list* tcl, struct config_file* cfg)

{

  struct config_str2list* p;

  for(p = cfg->tcp_connection_limits; p; p = p->next) {

    log_assert(p->str && p->str2);

    if(!tcl_list_str_cfg(tcl, p->str, p->str2, 1))

      return 0;

  }

  return 1;

}

int

tcl_list_apply_cfg(struct tcl_list* tcl, struct config_file* cfg)

{

  regional_free_all(tcl->region);

  addr_tree_init(&tcl->tree);

  if(!read_tcl_list(tcl, cfg))

    return 0;

  addr_tree_init_parents(&tcl->tree);

  return 1;

}

int

tcl_new_connection(struct tcl_addr* tcl)

{

  if(tcl) {

    int res = 1;

    lock_quick_lock(&tcl->lock);

    if(tcl->count >= tcl->limit)

      res = 0;

    else

      tcl->count++;

    lock_quick_unlock(&tcl->lock);

    return res;

  }

  return 1;

}

void

tcl_close_connection(struct tcl_addr* tcl)

{

  if(tcl) {

    lock_quick_lock(&tcl->lock);

    log_assert(tcl->count > 0);

    tcl->count--;

    lock_quick_unlock(&tcl->lock);

  }

}

struct tcl_addr*

tcl_addr_lookup(struct tcl_list* tcl, struct sockaddr_storage* addr,

        socklen_t addrlen)

{

  return (struct tcl_addr*)addr_tree_lookup(&tcl->tree,

    addr, addrlen);

}

size_t

tcl_list_get_mem(struct tcl_list* tcl)

{

  if(!tcl) return 0;

  return sizeof(*tcl) + regional_get_mem(tcl->region);

}

void tcl_list_swap_tree(struct tcl_list* tcl, struct tcl_list* data)

{

  /* swap tree and region */

  rbtree_type oldtree = tcl->tree;

  struct regional* oldregion = tcl->region;

  tcl->tree = data->tree;

  tcl->region = data->region;

  data->tree = oldtree;

  data->region = oldregion;

}