/*

 * util/edns.c - handle base EDNS options.

 *

 * 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 contains functions for base EDNS options.

 */

#include "config.h"

#include "util/edns.h"

#include "util/config_file.h"

#include "util/netevent.h"

#include "util/net_help.h"

#include "util/regional.h"

#include "util/rfc_1982.h"

#include "util/siphash.h"

#include "util/data/msgparse.h"

#include "util/data/msgreply.h"

#include "sldns/sbuffer.h"

struct edns_strings* edns_strings_create(void)

{

  struct edns_strings* edns_strings = calloc(1,

    sizeof(struct edns_strings));

  if(!edns_strings)

    return NULL;

  if(!(edns_strings->region = regional_create())) {

    edns_strings_delete(edns_strings);

    return NULL;

  }

  return edns_strings;

}

void edns_strings_delete(struct edns_strings* edns_strings)

{

  if(!edns_strings)

    return;

  regional_destroy(edns_strings->region);

  free(edns_strings);

}

static int

edns_strings_client_insert(struct edns_strings* edns_strings,

  struct sockaddr_storage* addr, socklen_t addrlen, int net,

  const char* string)

{

  struct edns_string_addr* esa = regional_alloc_zero(edns_strings->region,

    sizeof(struct edns_string_addr));

  if(!esa)

    return 0;

  esa->string_len = strlen(string);

  esa->string = regional_alloc_init(edns_strings->region, string,

    esa->string_len);

  if(!esa->string)

    return 0;

  if(!addr_tree_insert(&edns_strings->client_strings, &esa->node, addr,

    addrlen, net)) {

    verbose(VERB_QUERY, "duplicate EDNS client string ignored.");

  }

  return 1;

}

int edns_strings_apply_cfg(struct edns_strings* edns_strings,

  struct config_file* config)

{

  struct config_str2list* c;

  regional_free_all(edns_strings->region);

  addr_tree_init(&edns_strings->client_strings);

  for(c=config->edns_client_strings; c; c=c->next) {

    struct sockaddr_storage addr;

    socklen_t addrlen;

    int net;

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

    if(!netblockstrtoaddr(c->str, UNBOUND_DNS_PORT, &addr, &addrlen,

      &net)) {

      log_err("cannot parse EDNS client string IP netblock: "

        "%s", c->str);

      return 0;

    }

    if(!edns_strings_client_insert(edns_strings, &addr, addrlen,

      net, c->str2)) {

      log_err("out of memory while adding EDNS strings");

      return 0;

    }

  }

  edns_strings->client_string_opcode = config->edns_client_string_opcode;

  addr_tree_init_parents(&edns_strings->client_strings);

  return 1;

}

struct edns_string_addr*

edns_string_addr_lookup(rbtree_type* tree, struct sockaddr_storage* addr,

  socklen_t addrlen)

{

  return (struct edns_string_addr*)addr_tree_lookup(tree, addr, addrlen);

}

size_t

edns_strings_get_mem(struct edns_strings* edns_strings)

{

  if(!edns_strings) return 0;

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

}

void

edns_strings_swap_tree(struct edns_strings* edns_strings,

  struct edns_strings* data)

{

  rbtree_type tree = edns_strings->client_strings;

  uint16_t opcode = edns_strings->client_string_opcode;

  struct regional* region = edns_strings->region;

  edns_strings->client_strings = data->client_strings;

  edns_strings->client_string_opcode = data->client_string_opcode;

  edns_strings->region = data->region;

  data->client_strings = tree;

  data->client_string_opcode = opcode;

  data->region = region;

}

uint8_t*

edns_cookie_server_hash(const uint8_t* in, const uint8_t* secret, int v4,

  uint8_t* hash)

{

  v4?siphash(in, 20, secret, hash, 8):siphash(in, 32, secret, hash, 8);

  return hash;

}

void

edns_cookie_server_write(uint8_t* buf, const uint8_t* secret, int v4,

  uint32_t timestamp)

{

  uint8_t hash[8];

  buf[ 8] = 1;   /* Version */

  buf[ 9] = 0;   /* Reserved */

  buf[10] = 0;   /* Reserved */

  buf[11] = 0;   /* Reserved */

  sldns_write_uint32(buf + 12, timestamp);

  (void)edns_cookie_server_hash(buf, secret, v4, hash);

  memcpy(buf + 16, hash, 8);

}

enum edns_cookie_val_status

edns_cookie_server_validate(const uint8_t* cookie, size_t cookie_len,

  const uint8_t* secret, size_t secret_len, int v4,

  const uint8_t* hash_input, uint32_t now)

{

  uint8_t hash[8];

  uint32_t timestamp;

  uint32_t subt_1982 = 0; /* Initialize for the compiler; unused value */

  int comp_1982;

  if(cookie_len != 24)

    /* RFC9018 cookies are 24 bytes long */

    return COOKIE_STATUS_CLIENT_ONLY;

  if(secret_len != 16 ||  /* RFC9018 cookies have 16 byte secrets */

    cookie[8] != 1) /* RFC9018 cookies are cookie version 1 */

    return COOKIE_STATUS_INVALID;

  timestamp = sldns_read_uint32(cookie + 12);

  if((comp_1982 = compare_1982(now, timestamp)) > 0

    && (subt_1982 = subtract_1982(timestamp, now)) > 3600)

    /* Cookie is older than 1 hour (see RFC9018 Section 4.3.) */

    return COOKIE_STATUS_EXPIRED;

  if(comp_1982 <= 0 && subtract_1982(now, timestamp) > 300)

    /* Cookie time is more than 5 minutes in the future.

     * (see RFC9018 Section 4.3.) */

    return COOKIE_STATUS_FUTURE;

  if(memcmp(edns_cookie_server_hash(hash_input, secret, v4, hash),

    cookie + 16, 8) != 0)

    /* Hashes do not match */

    return COOKIE_STATUS_INVALID;

  if(comp_1982 > 0 && subt_1982 > 1800)

    /* Valid cookie but older than 30 minutes, so create a new one

     * anyway */

    return COOKIE_STATUS_VALID_RENEW;

  return COOKIE_STATUS_VALID;

}

struct cookie_secrets*

cookie_secrets_create(void)

{

  struct cookie_secrets* cookie_secrets = calloc(1,

    sizeof(*cookie_secrets));

  if(!cookie_secrets)

    return NULL;

  lock_basic_init(&cookie_secrets->lock);

  lock_protect(&cookie_secrets->lock, &cookie_secrets->cookie_count,

    sizeof(cookie_secrets->cookie_count));

  lock_protect(&cookie_secrets->lock, cookie_secrets->cookie_secrets,

    sizeof(cookie_secret_type)*UNBOUND_COOKIE_HISTORY_SIZE);

  return cookie_secrets;

}

void

cookie_secrets_delete(struct cookie_secrets* cookie_secrets)

{

  if(!cookie_secrets)

    return;

  lock_basic_destroy(&cookie_secrets->lock);

  explicit_bzero(cookie_secrets->cookie_secrets,

    sizeof(cookie_secret_type)*UNBOUND_COOKIE_HISTORY_SIZE);

  free(cookie_secrets);

}

/** Read the cookie secret file */

static int

cookie_secret_file_read(struct cookie_secrets* cookie_secrets,

  char* cookie_secret_file)

{

  char secret[UNBOUND_COOKIE_SECRET_SIZE * 2 + 2/*'\n' and '\0'*/];

  FILE* f;

  int corrupt = 0;

  size_t count;

  log_assert(cookie_secret_file != NULL);

  cookie_secrets->cookie_count = 0;

  f = fopen(cookie_secret_file, "r");

  /* a non-existing cookie file is not an error */

  if( f == NULL ) {

    if(errno != EPERM) {

      log_err("Could not read cookie-secret-file '%s': %s",

        cookie_secret_file, strerror(errno));

      return 0;

    }

    return 1;

  }

  /* cookie secret file exists and is readable */

  for( count = 0; count < UNBOUND_COOKIE_HISTORY_SIZE; count++ ) {

    size_t secret_len = 0;

    ssize_t decoded_len = 0;

    if( fgets(secret, sizeof(secret), f) == NULL ) { break; }

    secret_len = strlen(secret);

    if( secret_len == 0 ) { break; }

    log_assert( secret_len <= sizeof(secret) );

    secret_len = secret[secret_len - 1] == '\n' ? secret_len - 1 : secret_len;

    if( secret_len != UNBOUND_COOKIE_SECRET_SIZE * 2 ) { corrupt++; break; }

    /* needed for `hex_pton`; stripping potential `\n` */

    secret[secret_len] = '\0';

    decoded_len = hex_pton(secret, cookie_secrets->cookie_secrets[count].cookie_secret,

                           UNBOUND_COOKIE_SECRET_SIZE);

    if( decoded_len != UNBOUND_COOKIE_SECRET_SIZE ) { corrupt++; break; }

    cookie_secrets->cookie_count++;

  }

  fclose(f);

  return corrupt == 0;

}

int

cookie_secrets_apply_cfg(struct cookie_secrets* cookie_secrets,

  char* cookie_secret_file)

{

  if(!cookie_secrets) {

    if(!cookie_secret_file || !cookie_secret_file[0])

      return 1; /* There is nothing to read anyway */

    log_err("Could not read cookie secrets, no structure alloced");

    return 0;

  }

  if(!cookie_secret_file_read(cookie_secrets, cookie_secret_file))

    return 0;

  return 1;

}

enum edns_cookie_val_status

cookie_secrets_server_validate(const uint8_t* cookie, size_t cookie_len,

  struct cookie_secrets* cookie_secrets, int v4,

  const uint8_t* hash_input, uint32_t now)

{

  size_t i;

  enum edns_cookie_val_status cookie_val_status,

    last = COOKIE_STATUS_INVALID;

  if(!cookie_secrets)

    return COOKIE_STATUS_INVALID; /* There are no cookie secrets.*/

  lock_basic_lock(&cookie_secrets->lock);

  if(cookie_secrets->cookie_count == 0) {

    lock_basic_unlock(&cookie_secrets->lock);

    return COOKIE_STATUS_INVALID; /* There are no cookie secrets.*/

  }

  for(i=0; i<cookie_secrets->cookie_count; i++) {

    cookie_val_status = edns_cookie_server_validate(cookie,

      cookie_len,

      cookie_secrets->cookie_secrets[i].cookie_secret,

      UNBOUND_COOKIE_SECRET_SIZE, v4, hash_input, now);

    if(cookie_val_status == COOKIE_STATUS_VALID ||

      cookie_val_status == COOKIE_STATUS_VALID_RENEW) {

      lock_basic_unlock(&cookie_secrets->lock);

      /* For staging cookies, write a fresh cookie. */

      if(i != 0)

        return COOKIE_STATUS_VALID_RENEW;

      return cookie_val_status;

    }

    if(last == COOKIE_STATUS_INVALID)

      last = cookie_val_status; /* Store more interesting

        failure to return. */

  }

  lock_basic_unlock(&cookie_secrets->lock);

  return last;

}

void add_cookie_secret(struct cookie_secrets* cookie_secrets,

  uint8_t* secret, size_t secret_len)

{

  log_assert(secret_len == UNBOUND_COOKIE_SECRET_SIZE);

  (void)secret_len;

  if(!cookie_secrets)

    return;

  /* New cookie secret becomes the staging secret (position 1)

   * unless there is no active cookie yet, then it becomes the active

   * secret.  If the UNBOUND_COOKIE_HISTORY_SIZE > 2 then all staging cookies

   * are moved one position down.

   */

  if(cookie_secrets->cookie_count == 0) {

    memcpy( cookie_secrets->cookie_secrets->cookie_secret

           , secret, UNBOUND_COOKIE_SECRET_SIZE);

    cookie_secrets->cookie_count = 1;

    explicit_bzero(secret, UNBOUND_COOKIE_SECRET_SIZE);

    return;

  }

#if UNBOUND_COOKIE_HISTORY_SIZE > 2

  memmove( &cookie_secrets->cookie_secrets[2], &cookie_secrets->cookie_secrets[1]

         , sizeof(struct cookie_secret) * (UNBOUND_COOKIE_HISTORY_SIZE - 2));

#endif

  memcpy( cookie_secrets->cookie_secrets[1].cookie_secret

        , secret, UNBOUND_COOKIE_SECRET_SIZE);

  cookie_secrets->cookie_count = cookie_secrets->cookie_count     < UNBOUND_COOKIE_HISTORY_SIZE

                    ? cookie_secrets->cookie_count + 1 : UNBOUND_COOKIE_HISTORY_SIZE;

  explicit_bzero(secret, UNBOUND_COOKIE_SECRET_SIZE);

}

void activate_cookie_secret(struct cookie_secrets* cookie_secrets)

{

  uint8_t active_secret[UNBOUND_COOKIE_SECRET_SIZE];

  if(!cookie_secrets)

    return;

  /* The staging secret becomes the active secret.

   * The active secret becomes a staging secret.

   * If the UNBOUND_COOKIE_HISTORY_SIZE > 2 then all staging secrets are moved

   * one position up and the previously active secret becomes the last

   * staging secret.

   */

  if(cookie_secrets->cookie_count < 2)

    return;

  memcpy( active_secret, cookie_secrets->cookie_secrets[0].cookie_secret

        , UNBOUND_COOKIE_SECRET_SIZE);

  memmove( &cookie_secrets->cookie_secrets[0], &cookie_secrets->cookie_secrets[1]

         , sizeof(struct cookie_secret) * (UNBOUND_COOKIE_HISTORY_SIZE - 1));

  memcpy( cookie_secrets->cookie_secrets[cookie_secrets->cookie_count - 1].cookie_secret

        , active_secret, UNBOUND_COOKIE_SECRET_SIZE);

  explicit_bzero(active_secret, UNBOUND_COOKIE_SECRET_SIZE);

}

void drop_cookie_secret(struct cookie_secrets* cookie_secrets)

{

  if(!cookie_secrets)

    return;

  /* Drops a staging cookie secret. If there are more than one, it will

   * drop the last staging secret. */

  if(cookie_secrets->cookie_count < 2)

    return;

  explicit_bzero( cookie_secrets->cookie_secrets[cookie_secrets->cookie_count - 1].cookie_secret

                , UNBOUND_COOKIE_SECRET_SIZE);

  cookie_secrets->cookie_count -= 1;

}