res_mkquery(3)res_mkquery(3)NAMEres_mkquery - Make query messages for name servers
#include <sys/types.h> #include <netinet/in.h> #include
<arpa/nameser.h> #include <resolv.h>
const u_char *domain_name,
const char *data,
const u_char *reserved,
int buf_length );
Standard C Library (libc)
Specifies a query type. The usual type is QUERY, but the parameter can
be set to any of the query types defined in the arpa/nameser.h file.
Points to the 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 cur‐
rent 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 Authoritative 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 information Mailbox
information Mail routing information User (finger) information User ID
Group ID Points to the data that is sent to the name server as a search
key. The data is stored as a character array. Defines the size of the
array pointed to by the data parameter. Specifies a reserved and cur‐
rently unused parameter. Points to a location containing the query
message. Specifies the length of the message pointed to by the buffer
The res_mkquery() function makes packets for name servers in the Inter‐
net domain. The res_mkquery() function makes a standard query message
and places it in the location pointed to by the buffer parameter.
The res_mkquery() function is one of a set of subroutines that form the
resolver, a set of functions that resolve domain names. Global infor‐
mation that is used by the resolver functions is kept in the _res data
structure. The /include/resolv.h file contains the _res data structure
Upon successful completion, the res_mkquery() function returns the size
of the query. If the query is larger than the value of the buf_length
parameter, the function fails and returns a value of -1.
If an error occurs during a resolver operation, the h_errno external
variable is set. Error code values and reasons are defined in
Contains the name server and domain name.
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_query(3), res_search(3), res_send(3).