res_search(3)res_search(3)NAME
res_search, res_query - Query a domain server and check the response
SYNOPSIS
#include <sys/types.h> #include <netinet/in.h> #include
<arpa/nameser.h> #include <resolv.h>
int res_search(
const char *domain_name,
int class,
int type,
u_char *answer,
int answer_len );
The res_query() syntax is as follows: int res_query(
const char *domain_name,
int class,
int type,
u_char *answer,
int answer_len );
LIBRARY
Standard C Library (libc)
PARAMETERS
Points to the fully-qualified name of the domain. If the domain_name
parameter points to a single label and the RES_DEFNAMES bit is set, as
it is by default, the function appends domain_name to the current
domain name. The current domain name is defined by the name server in
use or in the /etc/resolv.conf file. Specifies one of the following
parameters: Specifies the ARPA Internet. Specifies the Chaos network
at MIT. Requires one of the following values: Host address Authorita‐
tive server Mail destination Mail forwarder Canonical name Start of
authority zone Mailbox domain name Mail group member Mail rename name
NULL resource record Well known service Domain name pointer Host infor‐
mation Mailbox information Mail routing information User (finger)
information User ID Group ID Points to a location of the server's
reply. Specifies the length of the answer pointed to by the answer
parameter.
DESCRIPTION
The res_search() and res_query() functions construct a query, send it
to the local server, and await a response. In addition, res_search()
implements the default and search rules specified by the RES_DEFNAMES
and RES_DNSRCH resolver options. The function returns the first suc‐
cessful reply.
The res_search() and res_query() functions part of a set of subroutines
that form the resolver, a set of functions that resolve domain names.
Global information that is used by the resolver functions is kept in
the _res data structure. The /include/resolv.h file contains the _res
data structure definition.
RETURN VALUES
Upon successful completion, the res_search() function returns the size
of the answer. If the answer is larger than the value of the answer_len
parameter, the function fails and returns a value of -1.
ERRORS
If an error occurs during a resolver operation, the h_errno external
variable is set. Error code values and reasons are defined in
<netdb.h>.
FILES
Contains the name server and domain name.
SEE ALSO
Functions: dn_comp(3), dn_expand(3), dn_find(3), dn_skipname(3), _get‐
long(3), _getshort(3), putlong(3), putshort(3), res_init(3),
res_mkquery(3), res_query(3), res_send(3).
res_search(3)