res_send() — Send resolver query for domain name servers

Standards

Format

#define _XOPEN_SOURCE_EXTENDED 1
#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/nameser.h>
#include <resolv.h>

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

General description

This routine is one of several functions used for sending query and reply messages with Internet domain name servers (DNS).

The res_send() routine sends a pre-formatted query and returns an answer. It will call res_init() if RES_INIT is not set, send the query to the local name server, and handle timeouts and retries. The length of the reply message is returned, or -1 if there were errors.

Returned value

If successful, res_send() returns the length of the reply message.

If unsuccessful, res_send() returns -1. The errors defined in <arpa/nameser.h> can be found in the buf.rcode, if an answer was supplied in the answer buffer.

Related information

• arpa/nameser.h
• netinet/in.h
• resolv.h
• sys/types.h
• dn_comp() — Resolver domain name compression
• dn_expand() — Resolver domain name expansion
• dn_find() — Resolver domain name find
• dn_skipname() — Resolver domain name skipping
• res_init() — Domain name resolver initialization
• res_mkquery() — Make resolver query for domain name servers
• res_query() — Resolver query for domain name servers
• res_querydomain() — Build domain name and resolver query
• res_search() — Resolver query for domain name servers