8.3.x/src/res.c

/*
 *  ircd-hybrid: an advanced, lightweight Internet Relay Chat Daemon (ircd)
 *
 *  Copyright (c) 1997-2015 ircd-hybrid development team
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301
 *  USA
 */

/*! \file res.c
 * \brief ircd resolver functions
 * \version $Id$
 */

/*
 * A rewrite of Darren Reed's original res.c As there is nothing
 * left of Darren's original code, this is now licensed by the hybrid group.
 * (Well, some of the function names are the same, and bits of the structs..)
 * You can use it where it is useful, free even. Buy us a beer and stuff.
 *
 * The authors takes no responsibility for any damage or loss
 * of property which results from the use of this software.
 *
 * July 1999 - Rewrote a bunch of stuff here. Change hostent builder code,
 *     added callbacks and reference counting of returned hostents.
 *     --Bleep (Thomas Helvey <tomh@inxpress.net>)
 *
 * This was all needlessly complicated for irc. Simplified. No more hostent
 * All we really care about is the IP -> hostname mappings. That's all.
 *
 * Apr 28, 2003 --cryogen and Dianora
 */

#include "stdinc.h"
#include "list.h"
#include "event.h"
#include "irc_string.h"
#include "ircd.h"
#include "rng_mt.h"
#include "fdlist.h"
#include "s_bsd.h"
#include "misc.h"
#include "mempool.h"
#include "res.h"
#include "reslib.h"

#if (CHAR_BIT != 8)
#error this code needs to be able to address individual octets
#endif

static void res_readreply(fde_t *, void *);

#define MAXPACKET      1024  /**< rfc says 512 but we expand names so ... */
#define AR_TTL         600   /**< TTL in seconds for dns cache entries */

/*
 * RFC 1104/1105 wasn't very helpful about what these fields
 * should be named, so for now, we'll just name them this way.
 * We probably should look at what named calls them or something.
 */
#define TYPE_SIZE         (size_t)2
#define CLASS_SIZE        (size_t)2
#define TTL_SIZE          (size_t)4
#define RDLENGTH_SIZE     (size_t)2
#define ANSWER_FIXED_SIZE (TYPE_SIZE + CLASS_SIZE + TTL_SIZE + RDLENGTH_SIZE)

struct reslist
{
  dlink_node node;                           /**< Doubly linked list node. */
  int id;                                    /**< Request ID (from request header). */
  int sent;                                  /**< Number of requests sent */
  char type;                                 /**< Current request type. */
  char retries;                              /**< Retry counter */
  unsigned int sends;                        /**< Number of sends (>1 means resent). */
  time_t sentat;                             /**< Timestamp we last sent this request. */
  time_t timeout;                            /**< When this request times out. */
  struct irc_ssaddr addr;                    /**< Address for this request. */
  char name[RFC1035_MAX_DOMAIN_LENGTH + 1];  /**< Hostname for this request. */
  size_t namelength;                         /**< Actual hostname length. */
  dns_callback_fnc callback;                 /**< Callback function on completion. */
  void *callback_ctx;                        /**< Context pointer for callback. */
};

static fde_t ResolverFileDescriptor;
static dlink_list request_list;
static mp_pool_t *dns_pool;


/*
 * rem_request - remove a request from the list.
 * This must also free any memory that has been allocated for
 * temporary storage of DNS results.
 */
static void
rem_request(struct reslist *request)
{
  dlinkDelete(&request->node, &request_list);
  mp_pool_release(request);
}

/*
 * make_request - Create a DNS request record for the server.
 */
static struct reslist *
make_request(dns_callback_fnc callback, void *ctx)
{
  struct reslist *request = mp_pool_get(dns_pool);

  request->sentat       = CurrentTime;
  request->retries      = 2;
  request->timeout      = 4;  /* Start at 4 and exponential inc. */
  request->callback     = callback;
  request->callback_ctx = ctx;

  dlinkAdd(request, &request->node, &request_list);
  return request;
}

/*
 * int
 * res_ourserver(inp)
 *      looks up "inp" in irc_nsaddr_list[]
 * returns:
 *      0  : not found
 *      >0 : found
 * author:
 *      paul vixie, 29may94
 *      revised for ircd, cryogen(stu) may03
 */
static int
res_ourserver(const struct irc_ssaddr *inp)
{
  const struct sockaddr_in6 *v6in = (const struct sockaddr_in6 *)inp;
  const struct sockaddr_in *v4in = (const struct sockaddr_in *)inp;

  for (unsigned int i = 0; i < irc_nscount; ++i)
  {
    const struct irc_ssaddr *srv = &irc_nsaddr_list[i];
    const struct sockaddr_in6 *v6 = (const struct sockaddr_in6 *)srv;
    const struct sockaddr_in *v4 = (const struct sockaddr_in *)srv;

    /*
     * Could probably just memcmp(srv, inp, srv.ss_len) here
     * but we'll air on the side of caution - stu
     */
    switch (srv->ss.ss_family)
    {
      case AF_INET6:
        if (srv->ss.ss_family == inp->ss.ss_family)
          if (v6->sin6_port == v6in->sin6_port)
            if (!memcmp(&v6->sin6_addr.s6_addr, &v6in->sin6_addr.s6_addr,
                        sizeof(struct in6_addr)))
              return 1;
        break;
      case AF_INET:
        if (srv->ss.ss_family == inp->ss.ss_family)
          if (v4->sin_port == v4in->sin_port)
            if (v4->sin_addr.s_addr == v4in->sin_addr.s_addr)
              return 1;
        break;
      default:
        break;
    }
  }

  return 0;
}

/*
 * start_resolver - do everything we need to read the resolv.conf file
 * and initialize the resolver file descriptor if needed
 */
static void
start_resolver(void)
{
  irc_res_init();

  if (!ResolverFileDescriptor.flags.open)
  {
    if (comm_open(&ResolverFileDescriptor, irc_nsaddr_list[0].ss.ss_family,
                  SOCK_DGRAM, 0, "UDP resolver socket") == -1)
      return;

    /* At the moment, the resolver FD data is global .. */
    comm_setselect(&ResolverFileDescriptor, COMM_SELECT_READ, res_readreply, NULL, 0);
  }
}

/*
 * restart_resolver - reread resolv.conf, reopen socket
 */
void
restart_resolver(void)
{
  fd_close(&ResolverFileDescriptor);
  start_resolver();
}

/*
 * delete_resolver_queries - cleanup outstanding queries
 * for which there no longer exist clients or conf lines.
 */
void
delete_resolver_queries(const void *vptr)
{
  dlink_node *node = NULL, *node_next = NULL;

  DLINK_FOREACH_SAFE(node, node_next, request_list.head)
  {
    struct reslist *request = node->data;

    if (request->callback_ctx == vptr)
      rem_request(request);
  }
}

/*
 * send_res_msg - sends msg to all nameservers found in the "_res" structure.
 * This should reflect /etc/resolv.conf. We will get responses
 * which arent needed but is easier than checking to see if nameserver
 * isn't present. Returns number of messages successfully sent to
 * nameservers or -1 if no successful sends.
 */
static int
send_res_msg(const unsigned char *msg, int len, unsigned int rcount)
{
  int sent = 0;
  unsigned int max_queries = IRCD_MIN(irc_nscount, rcount);

  /* RES_PRIMARY option is not implemented
   * if (res.options & RES_PRIMARY || 0 == max_queries)
   */
  if (max_queries == 0)
    max_queries = 1;

  for (unsigned int i = 0; i < max_queries; ++i)
  {
    if (sendto(ResolverFileDescriptor.fd, msg, len, 0,
        (struct sockaddr*)&(irc_nsaddr_list[i]),
        irc_nsaddr_list[i].ss_len) == len)
      ++sent;
  }

  return sent;
}

/*
 * find_id - find a dns request id (id is determined by dn_mkquery)
 */
static struct reslist *
find_id(int id)
{
  dlink_node *node = NULL;

  DLINK_FOREACH(node, request_list.head)
  {
    struct reslist *request = node->data;

    if (request->id == id)
      return request;
  }

  return NULL;
}

/*
 * query_name - generate a query based on class, type and name.
 */
static void
query_name(const char *name, int query_class, int type, struct reslist *request)
{
  unsigned char buf[MAXPACKET];
  int request_len = 0;

  memset(buf, 0, sizeof(buf));

  if ((request_len = irc_res_mkquery(name, query_class, type, buf, sizeof(buf))) > 0)
  {
    HEADER *header = (HEADER *)buf;

    /*
     * Generate an unique id.
     * NOTE: we don't have to worry about converting this to and from
     * network byte order, the nameserver does not interpret this value
     * and returns it unchanged.
     */
    do
      header->id = (header->id + genrand_int32()) & 0xFFFF;
    while (find_id(header->id));

    request->id = header->id;
    ++request->sends;

    request->sent += send_res_msg(buf, request_len, request->sends);
  }
}

/*
 * do_query_name - nameserver lookup name
 */
static void
do_query_name(dns_callback_fnc callback, void *ctx, const char *name,
              struct reslist *request, int type)
{
  char host_name[RFC1035_MAX_DOMAIN_LENGTH + 1];

  strlcpy(host_name, name, sizeof(host_name));

  if (request == NULL)
  {
    request             = make_request(callback, ctx);
    request->type       = type;
    request->namelength = strlcpy(request->name, host_name, sizeof(request->name));
  }

  request->type = type;
  query_name(host_name, C_IN, type, request);
}

/*
 * do_query_number - Use this to do reverse IP# lookups.
 */
static void
do_query_number(dns_callback_fnc callback, void *ctx,
                const struct irc_ssaddr *addr,
                struct reslist *request)
{
  char ipbuf[128] = "";

  if (addr->ss.ss_family == AF_INET)
  {
    const struct sockaddr_in *v4 = (const struct sockaddr_in *)addr;
    const unsigned char *cp = (const unsigned char *)&v4->sin_addr.s_addr;

    snprintf(ipbuf, sizeof(ipbuf), "%u.%u.%u.%u.in-addr.arpa.",
             (unsigned int)(cp[3]), (unsigned int)(cp[2]),
             (unsigned int)(cp[1]), (unsigned int)(cp[0]));
  }
  else if (addr->ss.ss_family == AF_INET6)
  {
    const struct sockaddr_in6 *v6 = (const struct sockaddr_in6 *)addr;
    const unsigned char *cp = (const unsigned char *)&v6->sin6_addr.s6_addr;

    snprintf(ipbuf, sizeof(ipbuf),
             "%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x."
             "%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.ip6.arpa.",
             (unsigned int)(cp[15] & 0xf), (unsigned int)(cp[15] >> 4),
             (unsigned int)(cp[14] & 0xf), (unsigned int)(cp[14] >> 4),
             (unsigned int)(cp[13] & 0xf), (unsigned int)(cp[13] >> 4),
             (unsigned int)(cp[12] & 0xf), (unsigned int)(cp[12] >> 4),
             (unsigned int)(cp[11] & 0xf), (unsigned int)(cp[11] >> 4),
             (unsigned int)(cp[10] & 0xf), (unsigned int)(cp[10] >> 4),
             (unsigned int)(cp[9] & 0xf), (unsigned int)(cp[9] >> 4),
             (unsigned int)(cp[8] & 0xf), (unsigned int)(cp[8] >> 4),
             (unsigned int)(cp[7] & 0xf), (unsigned int)(cp[7] >> 4),
             (unsigned int)(cp[6] & 0xf), (unsigned int)(cp[6] >> 4),
             (unsigned int)(cp[5] & 0xf), (unsigned int)(cp[5] >> 4),
             (unsigned int)(cp[4] & 0xf), (unsigned int)(cp[4] >> 4),
             (unsigned int)(cp[3] & 0xf), (unsigned int)(cp[3] >> 4),
             (unsigned int)(cp[2] & 0xf), (unsigned int)(cp[2] >> 4),
             (unsigned int)(cp[1] & 0xf), (unsigned int)(cp[1] >> 4),
             (unsigned int)(cp[0] & 0xf), (unsigned int)(cp[0] >> 4));
  }

  if (request == NULL)
  {
    request       = make_request(callback, ctx);
    request->type = T_PTR;
    memcpy(&request->addr, addr, sizeof(struct irc_ssaddr));
  }

  query_name(ipbuf, C_IN, T_PTR, request);
}

/*
 * gethost_byname_type - get host address from name
 *
 */
void
gethost_byname_type(dns_callback_fnc callback, void *ctx, const char *name, int type)
{
  assert(name);
  do_query_name(callback, ctx, name, NULL, type);
}

/*
 * gethost_byaddr - get host name from address
 */
void
gethost_byaddr(dns_callback_fnc callback, void *ctx, const struct irc_ssaddr *addr)
{
  do_query_number(callback, ctx, addr, NULL);
}

static void
resend_query(struct reslist *request)
{
  switch (request->type)
  {
    case T_PTR:
      do_query_number(NULL, NULL, &request->addr, request);
      break;
    case T_A:
    case T_AAAA:
      do_query_name(NULL, NULL, request->name, request, request->type);
      break;
    default:
      break;
  }
}

/*
 * proc_answer - process name server reply
 */
static int
proc_answer(struct reslist *request, HEADER *header, unsigned char *buf, unsigned char *eob)
{
  char hostbuf[RFC1035_MAX_DOMAIN_LENGTH + 100]; /* working buffer */
  unsigned char *current = buf + sizeof(HEADER); /* current position in buf */
  unsigned int type = 0;       /* answer type */
  unsigned int rd_length = 0;
  int n;                       /* temp count */
  struct sockaddr_in *v4;      /* conversion */
  struct sockaddr_in6 *v6;

  for (; header->qdcount > 0; --header->qdcount)
  {
    if ((n = irc_dn_skipname(current, eob)) < 0)
      break;

    current += (size_t)n + QFIXEDSZ;
  }

  /*
   * Process each answer sent to us blech.
   */
  while (header->ancount > 0 && current < eob)
  {
    header->ancount--;

    n = irc_dn_expand(buf, eob, current, hostbuf, sizeof(hostbuf));

    if (n < 0  /* Broken message */ || n == 0  /* No more answers left */)
      return 0;

    hostbuf[RFC1035_MAX_DOMAIN_LENGTH] = '\0';

    /*
     * With Address arithmetic you have to be very anal
     * this code was not working on alpha due to that
     * (spotted by rodder/jailbird/dianora)
     */
    current += (size_t)n;

    if (!((current + ANSWER_FIXED_SIZE) < eob))
      break;

    type = irc_ns_get16(current);
    current += TYPE_SIZE;
    current += CLASS_SIZE;
    current += TTL_SIZE;
    rd_length = irc_ns_get16(current);
    current += RDLENGTH_SIZE;

    /*
     * Wait to set request->type until we verify this structure
     */
    switch (type)
    {
      case T_A:
        if (request->type != T_A)
          return 0;

        /*
         * Check for invalid rd_length or too many addresses
         */
        if (rd_length != sizeof(struct in_addr))
          return 0;

        request->addr.ss_len = sizeof(struct sockaddr_in);
        v4 = (struct sockaddr_in *)&request->addr;
        v4->sin_family = AF_INET;
        memcpy(&v4->sin_addr, current, sizeof(struct in_addr));
        return 1;
        break;
      case T_AAAA:
        if (request->type != T_AAAA)
          return 0;

        if (rd_length != sizeof(struct in6_addr))
          return 0;

        request->addr.ss_len = sizeof(struct sockaddr_in6);
        v6 = (struct sockaddr_in6 *)&request->addr;
        v6->sin6_family = AF_INET6;
        memcpy(&v6->sin6_addr, current, sizeof(struct in6_addr));
        return 1;
        break;
      case T_PTR:
        if (request->type != T_PTR)
          return 0;

        n = irc_dn_expand(buf, eob, current, hostbuf, sizeof(hostbuf));
        if (n < 0  /* Broken message */ || n == 0  /* No more answers left */)
          return 0;

        request->namelength = strlcpy(request->name, hostbuf, sizeof(request->name));
        return 1;
        break;
      case T_CNAME:
        current += rd_length;
        break;
      default:
        return 0;
        break;
    }
  }

  return 0;
}

/*
 * res_readreply - read a dns reply from the nameserver and process it.
 */
static void
res_readreply(fde_t *fd, void *data)
{
  unsigned char buf[sizeof(HEADER) + MAXPACKET];
  HEADER *header;
  struct reslist *request = NULL;
  ssize_t rc = 0;
  socklen_t len = sizeof(struct irc_ssaddr);
  struct irc_ssaddr lsin;

  while ((rc = recvfrom(fd->fd, buf, sizeof(buf), 0, (struct sockaddr *)&lsin, &len)) != -1)
  {
    if (rc <= (ssize_t)sizeof(HEADER))
      continue;

    /*
     * Check against possibly fake replies
     */
    if (!res_ourserver(&lsin))
      continue;

    /*
     * Convert DNS reply reader from Network byte order to CPU byte order.
     */
    header = (HEADER *)buf;
    header->ancount = ntohs(header->ancount);
    header->qdcount = ntohs(header->qdcount);
    header->nscount = ntohs(header->nscount);
    header->arcount = ntohs(header->arcount);

    /*
     * Response for an id which we have already received an answer for
     * just ignore this response.
     */
    if ((request = find_id(header->id)) == NULL)
      continue;

    if (header->rcode != NO_ERRORS || header->ancount == 0)
    {
      /*
       * If a bad error was returned, stop here and don't
       * send any more (no retries granted).
       */
      (*request->callback)(request->callback_ctx, NULL, NULL, 0);
      rem_request(request);
      continue;
    }

    /*
     * If this fails there was an error decoding the received packet.
     * We only give it one shot. If it fails, just leave the client
     * unresolved.
     */
    if (!proc_answer(request, header, buf, buf + rc))
    {
      (*request->callback)(request->callback_ctx, NULL, NULL, 0);
      rem_request(request);
      continue;
    }

    if (request->type == T_PTR)
    {
      if (request->namelength == 0)
      {
        /*
         * Got a PTR response with no name, something bogus is happening
         * don't bother trying again, the client address doesn't resolve
         */
        (*request->callback)(request->callback_ctx, NULL, NULL, 0);
        rem_request(request);
        continue;
      }

      /*
       * Lookup the 'authoritative' name that we were given for the ip#.
       */
      if (request->addr.ss.ss_family == AF_INET6)
        gethost_byname_type(request->callback, request->callback_ctx, request->name, T_AAAA);
      else
        gethost_byname_type(request->callback, request->callback_ctx, request->name, T_A);
      rem_request(request);
    }
    else
    {
      /*
       * Got a name and address response, client resolved
       */
      (*request->callback)(request->callback_ctx, &request->addr, request->name, request->namelength);
      rem_request(request);
    }

    continue;
  }

  comm_setselect(fd, COMM_SELECT_READ, res_readreply, NULL, 0);
}

/*
 * timeout_query_list - Remove queries from the list which have been
 * there too long without being resolved.
 */
static time_t
timeout_query_list(void)
{
  dlink_node *node = NULL, *node_next = NULL;
  struct reslist *request = NULL;
  time_t next_time = 0;
  time_t timeout   = 0;

  DLINK_FOREACH_SAFE(node, node_next, request_list.head)
  {
    request = node->data;
    timeout = request->sentat + request->timeout;

    if (CurrentTime >= timeout)
    {
      if (--request->retries <= 0)
      {
        (*request->callback)(request->callback_ctx, NULL, NULL, 0);
        rem_request(request);
        continue;
      }
      else
      {
        request->sentat = CurrentTime;
        request->timeout += request->timeout;
        resend_query(request);
      }
    }

    if (next_time == 0 || timeout < next_time)
      next_time = timeout;
  }

  return (next_time > CurrentTime) ? next_time : (CurrentTime + AR_TTL);
}

/*
 * timeout_resolver - check request list
 */
static void
timeout_resolver(void *unused)
{
  timeout_query_list();
}

/*
 * init_resolver - initialize resolver and resolver library
 */
void
init_resolver(void)
{
  static struct event event_timeout_resolver =
  {
    .name = "timeout_resolver",
    .handler = timeout_resolver,
    .when = 1
  };

  dns_pool = mp_pool_new(sizeof(struct reslist), MP_CHUNK_SIZE_DNS);

  start_resolver();
  event_add(&event_timeout_resolver, NULL);
}
Revision:	6838
Committed:	Tue Nov 24 17:28:38 2015 UTC (10 years, 8 months ago) by michael
Content type:	text/x-csrc
File size:	19879 byte(s)
Log Message:	- res.c: remove unused header includes
#	Content
1	/*
2	* ircd-hybrid: an advanced, lightweight Internet Relay Chat Daemon (ircd)
3	*
4	* Copyright (c) 1997-2015 ircd-hybrid development team
5	*
6	* This program is free software; you can redistribute it and/or modify
7	* it under the terms of the GNU General Public License as published by
8	* the Free Software Foundation; either version 2 of the License, or
9	* (at your option) any later version.
10	*
11	* This program is distributed in the hope that it will be useful,
12	* but WITHOUT ANY WARRANTY; without even the implied warranty of
13	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14	* GNU General Public License for more details.
15	*
16	* You should have received a copy of the GNU General Public License
17	* along with this program; if not, write to the Free Software
18	* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301
19	* USA
20	*/
21
22	/*! \file res.c
23	* \brief ircd resolver functions
24	* \version $Id$
25	*/
26
27	/*
28	* A rewrite of Darren Reed's original res.c As there is nothing
29	* left of Darren's original code, this is now licensed by the hybrid group.
30	* (Well, some of the function names are the same, and bits of the structs..)
31	* You can use it where it is useful, free even. Buy us a beer and stuff.
32	*
33	* The authors takes no responsibility for any damage or loss
34	* of property which results from the use of this software.
35	*
36	* July 1999 - Rewrote a bunch of stuff here. Change hostent builder code,
37	* added callbacks and reference counting of returned hostents.
38	* --Bleep (Thomas Helvey <tomh@inxpress.net>)
39	*
40	* This was all needlessly complicated for irc. Simplified. No more hostent
41	* All we really care about is the IP -> hostname mappings. That's all.
42	*
43	* Apr 28, 2003 --cryogen and Dianora
44	*/
45
46	#include "stdinc.h"
47	#include "list.h"
48	#include "event.h"
49	#include "irc_string.h"
50	#include "ircd.h"
51	#include "rng_mt.h"
52	#include "fdlist.h"
53	#include "s_bsd.h"
54	#include "misc.h"
55	#include "mempool.h"
56	#include "res.h"
57	#include "reslib.h"
58
59	#if (CHAR_BIT != 8)
60	#error this code needs to be able to address individual octets
61	#endif
62
63	static void res_readreply(fde_t , void );
64
65	#define MAXPACKET 1024 /*< rfc says 512 but we expand names so ... /
66	#define AR_TTL 600 /*< TTL in seconds for dns cache entries /
67
68	/*
69	* RFC 1104/1105 wasn't very helpful about what these fields
70	* should be named, so for now, we'll just name them this way.
71	* We probably should look at what named calls them or something.
72	*/
73	#define TYPE_SIZE (size_t)2
74	#define CLASS_SIZE (size_t)2
75	#define TTL_SIZE (size_t)4
76	#define RDLENGTH_SIZE (size_t)2
77	#define ANSWER_FIXED_SIZE (TYPE_SIZE + CLASS_SIZE + TTL_SIZE + RDLENGTH_SIZE)
78
79	struct reslist
80	{
81	dlink_node node; /*< Doubly linked list node. /
82	int id; /*< Request ID (from request header). /
83	int sent; /*< Number of requests sent /
84	char type; /*< Current request type. /
85	char retries; /*< Retry counter /
86	unsigned int sends; /*< Number of sends (>1 means resent). /
87	time_t sentat; /*< Timestamp we last sent this request. /
88	time_t timeout; /*< When this request times out. /
89	struct irc_ssaddr addr; /*< Address for this request. /
90	char name[RFC1035_MAX_DOMAIN_LENGTH + 1]; /*< Hostname for this request. /
91	size_t namelength; /*< Actual hostname length. /
92	dns_callback_fnc callback; /*< Callback function on completion. /
93	void callback_ctx; /< Context pointer for callback. /
94	};
95
96	static fde_t ResolverFileDescriptor;
97	static dlink_list request_list;
98	static mp_pool_t *dns_pool;
99
100
101	/*
102	* rem_request - remove a request from the list.
103	* This must also free any memory that has been allocated for
104	* temporary storage of DNS results.
105	*/
106	static void
107	rem_request(struct reslist *request)
108	{
109	dlinkDelete(&request->node, &request_list);
110	mp_pool_release(request);
111	}
112
113	/*
114	* make_request - Create a DNS request record for the server.
115	*/
116	static struct reslist *
117	make_request(dns_callback_fnc callback, void *ctx)
118	{
119	struct reslist *request = mp_pool_get(dns_pool);
120
121	request->sentat = CurrentTime;
122	request->retries = 2;
123	request->timeout = 4; /* Start at 4 and exponential inc. */
124	request->callback = callback;
125	request->callback_ctx = ctx;
126
127	dlinkAdd(request, &request->node, &request_list);
128	return request;
129	}
130
131	/*
132	* int
133	* res_ourserver(inp)
134	* looks up "inp" in irc_nsaddr_list[]
135	* returns:
136	* 0 : not found
137	* >0 : found
138	* author:
139	* paul vixie, 29may94
140	* revised for ircd, cryogen(stu) may03
141	*/
142	static int
143	res_ourserver(const struct irc_ssaddr *inp)
144	{
145	const struct sockaddr_in6 v6in = (const struct sockaddr_in6 )inp;
146	const struct sockaddr_in v4in = (const struct sockaddr_in )inp;
147
148	for (unsigned int i = 0; i < irc_nscount; ++i)
149	{
150	const struct irc_ssaddr *srv = &irc_nsaddr_list[i];
151	const struct sockaddr_in6 v6 = (const struct sockaddr_in6 )srv;
152	const struct sockaddr_in v4 = (const struct sockaddr_in )srv;
153
154	/*
155	* Could probably just memcmp(srv, inp, srv.ss_len) here
156	* but we'll air on the side of caution - stu
157	*/
158	switch (srv->ss.ss_family)
159	{
160	case AF_INET6:
161	if (srv->ss.ss_family == inp->ss.ss_family)
162	if (v6->sin6_port == v6in->sin6_port)
163	if (!memcmp(&v6->sin6_addr.s6_addr, &v6in->sin6_addr.s6_addr,
164	sizeof(struct in6_addr)))
165	return 1;
166	break;
167	case AF_INET:
168	if (srv->ss.ss_family == inp->ss.ss_family)
169	if (v4->sin_port == v4in->sin_port)
170	if (v4->sin_addr.s_addr == v4in->sin_addr.s_addr)
171	return 1;
172	break;
173	default:
174	break;
175	}
176	}
177
178	return 0;
179	}
180
181	/*
182	* start_resolver - do everything we need to read the resolv.conf file
183	* and initialize the resolver file descriptor if needed
184	*/
185	static void
186	start_resolver(void)
187	{
188	irc_res_init();
189
190	if (!ResolverFileDescriptor.flags.open)
191	{
192	if (comm_open(&ResolverFileDescriptor, irc_nsaddr_list[0].ss.ss_family,
193	SOCK_DGRAM, 0, "UDP resolver socket") == -1)
194	return;
195
196	/* At the moment, the resolver FD data is global .. */
197	comm_setselect(&ResolverFileDescriptor, COMM_SELECT_READ, res_readreply, NULL, 0);
198	}
199	}
200
201	/*
202	* restart_resolver - reread resolv.conf, reopen socket
203	*/
204	void
205	restart_resolver(void)
206	{
207	fd_close(&ResolverFileDescriptor);
208	start_resolver();
209	}
210
211	/*
212	* delete_resolver_queries - cleanup outstanding queries
213	* for which there no longer exist clients or conf lines.
214	*/
215	void
216	delete_resolver_queries(const void *vptr)
217	{
218	dlink_node node = NULL, node_next = NULL;
219
220	DLINK_FOREACH_SAFE(node, node_next, request_list.head)
221	{
222	struct reslist *request = node->data;
223
224	if (request->callback_ctx == vptr)
225	rem_request(request);
226	}
227	}
228
229	/*
230	* send_res_msg - sends msg to all nameservers found in the "_res" structure.
231	* This should reflect /etc/resolv.conf. We will get responses
232	* which arent needed but is easier than checking to see if nameserver
233	* isn't present. Returns number of messages successfully sent to
234	* nameservers or -1 if no successful sends.
235	*/
236	static int
237	send_res_msg(const unsigned char *msg, int len, unsigned int rcount)
238	{
239	int sent = 0;
240	unsigned int max_queries = IRCD_MIN(irc_nscount, rcount);
241
242	/* RES_PRIMARY option is not implemented
243	* if (res.options & RES_PRIMARY \|\| 0 == max_queries)
244	*/
245	if (max_queries == 0)
246	max_queries = 1;
247
248	for (unsigned int i = 0; i < max_queries; ++i)
249	{
250	if (sendto(ResolverFileDescriptor.fd, msg, len, 0,
251	(struct sockaddr*)&(irc_nsaddr_list[i]),
252	irc_nsaddr_list[i].ss_len) == len)
253	++sent;
254	}
255
256	return sent;
257	}
258
259	/*
260	* find_id - find a dns request id (id is determined by dn_mkquery)
261	*/
262	static struct reslist *
263	find_id(int id)
264	{
265	dlink_node *node = NULL;
266
267	DLINK_FOREACH(node, request_list.head)
268	{
269	struct reslist *request = node->data;
270
271	if (request->id == id)
272	return request;
273	}
274
275	return NULL;
276	}
277
278	/*
279	* query_name - generate a query based on class, type and name.
280	*/
281	static void
282	query_name(const char name, int query_class, int type, struct reslist request)
283	{
284	unsigned char buf[MAXPACKET];
285	int request_len = 0;
286
287	memset(buf, 0, sizeof(buf));
288
289	if ((request_len = irc_res_mkquery(name, query_class, type, buf, sizeof(buf))) > 0)
290	{
291	HEADER header = (HEADER )buf;
292
293	/*
294	* Generate an unique id.
295	* NOTE: we don't have to worry about converting this to and from
296	* network byte order, the nameserver does not interpret this value
297	* and returns it unchanged.
298	*/
299	do
300	header->id = (header->id + genrand_int32()) & 0xFFFF;
301	while (find_id(header->id));
302
303	request->id = header->id;
304	++request->sends;
305
306	request->sent += send_res_msg(buf, request_len, request->sends);
307	}
308	}
309
310	/*
311	* do_query_name - nameserver lookup name
312	*/
313	static void
314	do_query_name(dns_callback_fnc callback, void ctx, const char name,
315	struct reslist *request, int type)
316	{
317	char host_name[RFC1035_MAX_DOMAIN_LENGTH + 1];
318
319	strlcpy(host_name, name, sizeof(host_name));
320
321	if (request == NULL)
322	{
323	request = make_request(callback, ctx);
324	request->type = type;
325	request->namelength = strlcpy(request->name, host_name, sizeof(request->name));
326	}
327
328	request->type = type;
329	query_name(host_name, C_IN, type, request);
330	}
331
332	/*
333	* do_query_number - Use this to do reverse IP# lookups.
334	*/
335	static void
336	do_query_number(dns_callback_fnc callback, void *ctx,
337	const struct irc_ssaddr *addr,
338	struct reslist *request)
339	{
340	char ipbuf[128] = "";
341
342	if (addr->ss.ss_family == AF_INET)
343	{
344	const struct sockaddr_in v4 = (const struct sockaddr_in )addr;
345	const unsigned char cp = (const unsigned char )&v4->sin_addr.s_addr;
346
347	snprintf(ipbuf, sizeof(ipbuf), "%u.%u.%u.%u.in-addr.arpa.",
348	(unsigned int)(cp[3]), (unsigned int)(cp[2]),
349	(unsigned int)(cp[1]), (unsigned int)(cp[0]));
350	}
351	else if (addr->ss.ss_family == AF_INET6)
352	{
353	const struct sockaddr_in6 v6 = (const struct sockaddr_in6 )addr;
354	const unsigned char cp = (const unsigned char )&v6->sin6_addr.s6_addr;
355
356	snprintf(ipbuf, sizeof(ipbuf),
357	"%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x."
358	"%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.ip6.arpa.",
359	(unsigned int)(cp[15] & 0xf), (unsigned int)(cp[15] >> 4),
360	(unsigned int)(cp[14] & 0xf), (unsigned int)(cp[14] >> 4),
361	(unsigned int)(cp[13] & 0xf), (unsigned int)(cp[13] >> 4),
362	(unsigned int)(cp[12] & 0xf), (unsigned int)(cp[12] >> 4),
363	(unsigned int)(cp[11] & 0xf), (unsigned int)(cp[11] >> 4),
364	(unsigned int)(cp[10] & 0xf), (unsigned int)(cp[10] >> 4),
365	(unsigned int)(cp[9] & 0xf), (unsigned int)(cp[9] >> 4),
366	(unsigned int)(cp[8] & 0xf), (unsigned int)(cp[8] >> 4),
367	(unsigned int)(cp[7] & 0xf), (unsigned int)(cp[7] >> 4),
368	(unsigned int)(cp[6] & 0xf), (unsigned int)(cp[6] >> 4),
369	(unsigned int)(cp[5] & 0xf), (unsigned int)(cp[5] >> 4),
370	(unsigned int)(cp[4] & 0xf), (unsigned int)(cp[4] >> 4),
371	(unsigned int)(cp[3] & 0xf), (unsigned int)(cp[3] >> 4),
372	(unsigned int)(cp[2] & 0xf), (unsigned int)(cp[2] >> 4),
373	(unsigned int)(cp[1] & 0xf), (unsigned int)(cp[1] >> 4),
374	(unsigned int)(cp[0] & 0xf), (unsigned int)(cp[0] >> 4));
375	}
376
377	if (request == NULL)
378	{
379	request = make_request(callback, ctx);
380	request->type = T_PTR;
381	memcpy(&request->addr, addr, sizeof(struct irc_ssaddr));
382	}
383
384	query_name(ipbuf, C_IN, T_PTR, request);
385	}
386
387	/*
388	* gethost_byname_type - get host address from name
389	*
390	*/
391	void
392	gethost_byname_type(dns_callback_fnc callback, void ctx, const char name, int type)
393	{
394	assert(name);
395	do_query_name(callback, ctx, name, NULL, type);
396	}
397
398	/*
399	* gethost_byaddr - get host name from address
400	*/
401	void
402	gethost_byaddr(dns_callback_fnc callback, void ctx, const struct irc_ssaddr addr)
403	{
404	do_query_number(callback, ctx, addr, NULL);
405	}
406
407	static void
408	resend_query(struct reslist *request)
409	{
410	switch (request->type)
411	{
412	case T_PTR:
413	do_query_number(NULL, NULL, &request->addr, request);
414	break;
415	case T_A:
416	case T_AAAA:
417	do_query_name(NULL, NULL, request->name, request, request->type);
418	break;
419	default:
420	break;
421	}
422	}
423
424	/*
425	* proc_answer - process name server reply
426	*/
427	static int
428	proc_answer(struct reslist request, HEADER header, unsigned char buf, unsigned char eob)
429	{
430	char hostbuf[RFC1035_MAX_DOMAIN_LENGTH + 100]; /* working buffer */
431	unsigned char current = buf + sizeof(HEADER); / current position in buf */
432	unsigned int type = 0; /* answer type */
433	unsigned int rd_length = 0;
434	int n; /* temp count */
435	struct sockaddr_in v4; / conversion */
436	struct sockaddr_in6 *v6;
437
438	for (; header->qdcount > 0; --header->qdcount)
439	{
440	if ((n = irc_dn_skipname(current, eob)) < 0)
441	break;
442
443	current += (size_t)n + QFIXEDSZ;
444	}
445
446	/*
447	* Process each answer sent to us blech.
448	*/
449	while (header->ancount > 0 && current < eob)
450	{
451	header->ancount--;
452
453	n = irc_dn_expand(buf, eob, current, hostbuf, sizeof(hostbuf));
454
455	if (n < 0 /* Broken message / \|\| n == 0 / No more answers left */)
456	return 0;
457
458	hostbuf[RFC1035_MAX_DOMAIN_LENGTH] = '\0';
459
460	/*
461	* With Address arithmetic you have to be very anal
462	* this code was not working on alpha due to that
463	* (spotted by rodder/jailbird/dianora)
464	*/
465	current += (size_t)n;
466
467	if (!((current + ANSWER_FIXED_SIZE) < eob))
468	break;
469
470	type = irc_ns_get16(current);
471	current += TYPE_SIZE;
472	current += CLASS_SIZE;
473	current += TTL_SIZE;
474	rd_length = irc_ns_get16(current);
475	current += RDLENGTH_SIZE;
476
477	/*
478	* Wait to set request->type until we verify this structure
479	*/
480	switch (type)
481	{
482	case T_A:
483	if (request->type != T_A)
484	return 0;
485
486	/*
487	* Check for invalid rd_length or too many addresses
488	*/
489	if (rd_length != sizeof(struct in_addr))
490	return 0;
491
492	request->addr.ss_len = sizeof(struct sockaddr_in);
493	v4 = (struct sockaddr_in *)&request->addr;
494	v4->sin_family = AF_INET;
495	memcpy(&v4->sin_addr, current, sizeof(struct in_addr));
496	return 1;
497	break;
498	case T_AAAA:
499	if (request->type != T_AAAA)
500	return 0;
501
502	if (rd_length != sizeof(struct in6_addr))
503	return 0;
504
505	request->addr.ss_len = sizeof(struct sockaddr_in6);
506	v6 = (struct sockaddr_in6 *)&request->addr;
507	v6->sin6_family = AF_INET6;
508	memcpy(&v6->sin6_addr, current, sizeof(struct in6_addr));
509	return 1;
510	break;
511	case T_PTR:
512	if (request->type != T_PTR)
513	return 0;
514
515	n = irc_dn_expand(buf, eob, current, hostbuf, sizeof(hostbuf));
516	if (n < 0 /* Broken message / \|\| n == 0 / No more answers left */)
517	return 0;
518
519	request->namelength = strlcpy(request->name, hostbuf, sizeof(request->name));
520	return 1;
521	break;
522	case T_CNAME:
523	current += rd_length;
524	break;
525	default:
526	return 0;
527	break;
528	}
529	}
530
531	return 0;
532	}
533
534	/*
535	* res_readreply - read a dns reply from the nameserver and process it.
536	*/
537	static void
538	res_readreply(fde_t fd, void data)
539	{
540	unsigned char buf[sizeof(HEADER) + MAXPACKET];
541	HEADER *header;
542	struct reslist *request = NULL;
543	ssize_t rc = 0;
544	socklen_t len = sizeof(struct irc_ssaddr);
545	struct irc_ssaddr lsin;
546
547	while ((rc = recvfrom(fd->fd, buf, sizeof(buf), 0, (struct sockaddr *)&lsin, &len)) != -1)
548	{
549	if (rc <= (ssize_t)sizeof(HEADER))
550	continue;
551
552	/*
553	* Check against possibly fake replies
554	*/
555	if (!res_ourserver(&lsin))
556	continue;
557
558	/*
559	* Convert DNS reply reader from Network byte order to CPU byte order.
560	*/
561	header = (HEADER *)buf;
562	header->ancount = ntohs(header->ancount);
563	header->qdcount = ntohs(header->qdcount);
564	header->nscount = ntohs(header->nscount);
565	header->arcount = ntohs(header->arcount);
566
567	/*
568	* Response for an id which we have already received an answer for
569	* just ignore this response.
570	*/
571	if ((request = find_id(header->id)) == NULL)
572	continue;
573
574	if (header->rcode != NO_ERRORS \|\| header->ancount == 0)
575	{
576	/*
577	* If a bad error was returned, stop here and don't
578	* send any more (no retries granted).
579	*/
580	(*request->callback)(request->callback_ctx, NULL, NULL, 0);
581	rem_request(request);
582	continue;
583	}
584
585	/*
586	* If this fails there was an error decoding the received packet.
587	* We only give it one shot. If it fails, just leave the client
588	* unresolved.
589	*/
590	if (!proc_answer(request, header, buf, buf + rc))
591	{
592	(*request->callback)(request->callback_ctx, NULL, NULL, 0);
593	rem_request(request);
594	continue;
595	}
596
597	if (request->type == T_PTR)
598	{
599	if (request->namelength == 0)
600	{
601	/*
602	* Got a PTR response with no name, something bogus is happening
603	* don't bother trying again, the client address doesn't resolve
604	*/
605	(*request->callback)(request->callback_ctx, NULL, NULL, 0);
606	rem_request(request);
607	continue;
608	}
609
610	/*
611	* Lookup the 'authoritative' name that we were given for the ip#.
612	*/
613	if (request->addr.ss.ss_family == AF_INET6)
614	gethost_byname_type(request->callback, request->callback_ctx, request->name, T_AAAA);
615	else
616	gethost_byname_type(request->callback, request->callback_ctx, request->name, T_A);
617	rem_request(request);
618	}
619	else
620	{
621	/*
622	* Got a name and address response, client resolved
623	*/
624	(*request->callback)(request->callback_ctx, &request->addr, request->name, request->namelength);
625	rem_request(request);
626	}
627
628	continue;
629	}
630
631	comm_setselect(fd, COMM_SELECT_READ, res_readreply, NULL, 0);
632	}
633
634	/*
635	* timeout_query_list - Remove queries from the list which have been
636	* there too long without being resolved.
637	*/
638	static time_t
639	timeout_query_list(void)
640	{
641	dlink_node node = NULL, node_next = NULL;
642	struct reslist *request = NULL;
643	time_t next_time = 0;
644	time_t timeout = 0;
645
646	DLINK_FOREACH_SAFE(node, node_next, request_list.head)
647	{
648	request = node->data;
649	timeout = request->sentat + request->timeout;
650
651	if (CurrentTime >= timeout)
652	{
653	if (--request->retries <= 0)
654	{
655	(*request->callback)(request->callback_ctx, NULL, NULL, 0);
656	rem_request(request);
657	continue;
658	}
659	else
660	{
661	request->sentat = CurrentTime;
662	request->timeout += request->timeout;
663	resend_query(request);
664	}
665	}
666
667	if (next_time == 0 \|\| timeout < next_time)
668	next_time = timeout;
669	}
670
671	return (next_time > CurrentTime) ? next_time : (CurrentTime + AR_TTL);
672	}
673
674	/*
675	* timeout_resolver - check request list
676	*/
677	static void
678	timeout_resolver(void *unused)
679	{
680	timeout_query_list();
681	}
682
683	/*
684	* init_resolver - initialize resolver and resolver library
685	*/
686	void
687	init_resolver(void)
688	{
689	static struct event event_timeout_resolver =
690	{
691	.name = "timeout_resolver",
692	.handler = timeout_resolver,
693	.when = 1
694	};
695
696	dns_pool = mp_pool_new(sizeof(struct reslist), MP_CHUNK_SIZE_DNS);
697
698	start_resolver();
699	event_add(&event_timeout_resolver, NULL);
700	}