NAME

res_mkquery − Makes query messages for name servers

LIBRARY

Standard C Library (libc.a)

SYNOPSIS

#include <sys/types.h> #include <netinet/in.h> #include <arpa/nameser.h> #include <resolv.h> int res_mkquery (
int query_type,
char ∗domain_name,
int class,
int type,
char ∗data,
int data_length,
struct rrec ∗reserved,
char ∗buffer,
int buf_length );

PARAMETERS

query_typeSpecifies 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. 

domain_name
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 current domain name is defined by the name server in use or in the /etc/resolv.conf file. 

classSpecifies one of the following parameters:

C_INSpecifies the ARPA Internet. 

C_CHAOSSpecifies the Chaos network at MIT. 

typeRequires one of the following values:

T_AHost address

T_NSAuthoritative server

T_MDMail destination

T_MFMail forwarder

T_CNAMECanonical name

T_SOAStart of authority zone

T_MBMailbox domain name

T_MGMail group member

T_MRMail rename name

T_NULLNULL resource record

T_WKSWell known service

T_PTRDomain name pointer

T_HINFOHost information

T_MINFOMailbox information

T_MXMail routing information

T_UINFOUser (finger) information

T_UIDUser ID

T_GIDGroup ID

dataPoints to the data that is sent to the name server as a search key.  The data is stored as a character array. 

data_lengthDefines the size of the array pointed to by the data parameter. 

reservedSpecifies a reserved and currently unused parameter. 

bufferPoints to a location containing the query message. 

buf_lengthSpecifies the length of the message pointed to by the buffer parameter. 

DESCRIPTION

The res_mkquery() function makes packets for name servers in the Internet 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 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_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. 

FILES

/etc/resolv.conf
Contains the name server and domain name.

RELATED INFORMATION

Functions: dn_comp(3), dn_expand(3), dn_find(3), dn_skipname(3), _getlong(3), _getshort(3), putlong(3), putshort(3), res_init(3), res_send(3)