val_gethostbyaddr






val_gethostbyname(), val_gethostbyname2(),
val_gethostbyname_r(), val_gethostbyname2_r() − get
DNSSEC−validated network host entry


  #include <validator/validator.h>

  extern int h_errno;
  struct hostent *val_gethostbyname(const val_context_t *ctx,
                                    const char *name,
                                    val_status_t *val_status);

  struct hostent *val_gethostbyname2(const val_context_t *ctx,
                                     const char *name,
                                     int af,
                                     val_status_t *val_status);

  int val_gethostbyname_r(const val_context_t *ctx,
                          const char *name,
                          struct hostent *ret,
                          char *buf,
                          size_t buflen,
                          struct hostent **result,
                          int *h_errnop,
                          val_status_t *val_status);

  int val_gethostbyname2_r(const val_context_t *ctx,
                           const char *name,
                           int af,
                           struct hostent *ret,
                           char *buf,
                           size_t buflen,
                           struct hostent **result,
                           int *h_errnop,
                           val_status_t *val_status);

    struct hostent *val_gethostbyaddr(val_context_t * ctx,
                                      const char *addr,
                                      int len,
                                      int type,
                                      val_status_t * val_status);

    int val_gethostbyaddr_r(val_context_t * ctx,
                            const char *addr,
                            int len,
                            int type,
                            struct hostent *ret,
                            char *buf,
                            int buflen,
                            struct hostent **result,
                            int *h_errnop,
                            val_status_t * val_status);











                             ‐2‐


val_gethostbyname(), val_gethostbyname2(),
val_gethostbyname_r(), val_gethostbyname2_r(),
val_gethostbyaddr() and val_gethostbyaddr_r() perform DNSSEC
validation of DNS queries.  They return a network host entry
value of type struct hostent and are DNSSEC‐aware versions
of the gethostbyname(3), gethostbyname2(3),
gethostbyname_r(), gethostbyname2_r(), gethostbyaddr() and
gethostbyaddr_r() functions respectively.  (See
gethostbyname(3) for more information on type struct
hostent).

     val_gethostbyname(), val_gethostbyname_r(),
val_gethostbyaddr(), and val_gethostbyaddr_r() support only
IPv4 addresses.  val_gethostbyname2() and
val_gethostbyname2_r() support both IPv4 and IPv6 addresses.

     The val_gethostbyname_r(), val_gethostbyname2_r() and
val_gethostbyaddr_r() functions are reentrant versions and
can be safely used in multi‐threaded applications.

     The ctx parameter specifies the validation context,
which can be set to NULL for default values (see libval(3)
and dnsval.conf for more details on validation contexts and
validation policy).

     val_gethostbyname(), val_gethostbyname2() and
val_gethostbyaddr() set the global h_errno variable to
return the resolver error code.  The reentrant versions
val_gethostbyname_r(), val_gethostbyname2_r() and
val_gethostbyaddr_r() use the h_errnop parameter to return
this value.  This ensures thread safety, by avoiding the
global h_errno variable.  h_errnop must not be NULL.  (See
the man page for gethostbyname(3) for possible values of
h_errno.)

     The name, af, ret, buf, buflen, and result parameters
have the same syntax and semantics as the corresponding
parameters for the original gethostbyname*() and
gethostbyaddr*() functions.  See the manual page for
gethostbyname(3) for more details about these parameters.

     The val_status parameter is used to return the
validator error code and must not be NULL.  val_istrusted()
and val_isvalidated() can be used to determine the
trustworthiness of data and p_val_status() can be used to
display the status value to the user in ASCII format (See
libval(3) more for information).

The val_gethostbyname(), val_gethostbyname2(), and
val_gethostbyaddr() functions return a pointer to a hostent
structure when they can resolve the given host name (with or
without DNSSEC validation), and NULL if data was not
available.  The memory for the returned value is statically
allocated by these two functions.  Hence, the caller must









                             ‐3‐


not free the memory for the returned value.

     The val_gethostbyname_r(), val_gethostbyname2_r() and
val_gethostbyaddr_r() functions return 0 when they can
resolve the given host name (with or without DNSSEC
validation), and a non‐zero error‐code on failure.

     The val_gethostbyaddr() and val_gethostbyaddr_r()
functions return 0 when they can resolve the given host name
(with or without DNSSEC validation), and a non‐zero error‐
code on failure.

     The val_status parameter gives an indication for
trustworthiness of data.  If the returned hostent structure
is NULL, this value gives an indication of whether the non‐
existence of data can be trusted or not.


 #include <stdio.h>
 #include <stdlib.h>
 #include <validator.h>

    int main(int argc, char *argv[])
    {
         int val_status;
         struct hostent *h = NULL;

         if (argc < 2) {
             printf("Usage: %s <hostname>\n", argv[0]);
             exit(1);
         }

         h = val_gethostbyname(NULL, argv[1], &val_status);
         printf("h_errno = %d [%s]\n", h_errno,
             hstrerror(h_errno));
         if (h) {
             printf("Validation Status = %d [%s]\n", val_status,
                    p_val_status(val_status));
         }

         return 0;
    }

These functions do not currently read the order of lookup
from /etc/hosts.conf.  At present, the default order is set
to consult the /etc/hosts file first and then query DNS.

     The current versions of these functions do not support
NIS lookups.

Copyright 2004−2013 SPARTA, Inc.  All rights reserved.  See
the COPYING file included with the DNSSEC‐Tools package for
details.










                             ‐4‐


Abhijit Hayatnagarkar, Suresh Krishnaswamy.

gethostbyname(3), gethostbyname2(3), gethostbyname_r(3),
gethostbyname2_r(3)

     val_getaddrinfo(3), val_res_query(3)

     libval(3)

     http://www.dnssec−tools.org