res_send()

send a preformatted Internet domain name query

Synopsis:

#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/nameser.h>
#include <resolv.h>

int res_send( const char *msg, 
              int msglen, 
              char *answer,
              int anslen );

Description:

The res_send() function is a low-level routine that's used by res_query() to send a preformatted Internet domain name query and return an answer. It calls res_init() if RES_INIT isn't set, sends the query to the local name server, and handles timeouts and retries.

The resolver routines are used for making, sending, and interpreting query and reply messages with Internet domain name servers.

Global configuration and state information used by the resolver routines is kept in the structure _res. For more information on the options, see res_init().

Returns:

The length of a reply message, in bytes, or -1 if an error occurs.

Files:

/etc/resolv.conf
Resolver configuration file.

Environment variables:

LOCALDOMAIN
When set, LOCALDOMAIN contains a domain name that overrides the current domain name.

Classification:

UNIX

Safety:
Interrupt handler No
Signal handler No
Thread No

See also:

dn_comp(), dn_expand(), gethostbyname(), res_init(), res_mkquery(), res_query(), res_search()

/etc/resolv.conf, hostname, named in the TCP/IP User's Guide

RFC 1032, RFC 1033, RFC 1034, RFC 1035, RFC 974