ares_send - Initiate a DNS query
#include <ares.h> typedef void (*ares_callback)(void *arg, int status, int timeouts, unsigned char *abuf, int alen) void ares_send(ares_channel channel, const unsigned char *qbuf, int qlen, ares_callback callback, void *arg)
ARES_SEND(3) Library Functions Manual ARES_SEND(3)
NAME
ares_send - Initiate a DNS query
SYNOPSIS
#include <ares.h>
typedef void (*ares_callback)(void *arg, int status,
int timeouts, unsigned char *abuf, int alen)
void ares_send(ares_channel channel, const unsigned char *qbuf,
int qlen, ares_callback callback, void *arg)
DESCRIPTION
The ares_send function initiates a DNS query on the name service chan-
nel identified by channel. The parameters qbuf and qlen give the DNS
query, which should already have been formatted according to the DNS
protocol. When the query is complete or has failed, the ares library
will invoke callback. Completion or failure of the query may happen
immediately, or may happen during a later call to ares_process(3) or
ares_destroy(3).
The callback argument arg is copied from the ares_send argument arg.
The callback argument status indicates whether the query succeeded and,
if not, how it failed. It may have any of the following values:
ARES_SUCCESS The query completed.
ARES_EBADQUERY The query buffer was poorly formed (was not long
enough for a DNS header or was too long for TCP
transmission).
ARES_ETIMEOUT No name servers responded within the timeout period.
ARES_ECONNREFUSED No name servers could be contacted.
ARES_ENOMEM Memory was exhausted.
ARES_ECANCELLED The query was cancelled.
ARES_EDESTRUCTION The name service channel channel is being destroyed;
the query will not be completed.
The callback argument timeouts reports how many times a query timed out
during the execution of the given request.
If the query completed, the callback argument abuf points to a result
buffer of length alen. If the query did not complete, abuf will be
NULL and alen will be 0.
Unless the flag ARES_FLAG_NOCHECKRESP was set at channel initialization
time, ares_send will normally ignore responses whose questions do not
match the questions in qbuf, as well as responses with reply codes of
SERVFAIL, NOTIMP, and REFUSED. Unlike other query functions in the
ares library, however, ares_send does not inspect the header of the
reply packet to determine the error status, so a callback status of
ARES_SUCCESS does not reflect as much about the response as for other
query functions.
ATTRIBUTES
See attributes(7) for descriptions of the following attributes:
+---------------+------------------+
|ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+---------------+------------------+
|Availability | library/libcares |
+---------------+------------------+
|Stability | Volatile |
+---------------+------------------+
SEE ALSO
ares_process(3)
AUTHOR
Greg Hudson, MIT Information Systems
Copyright 1998 by the Massachusetts Institute of Technology.
NOTES
Source code for open source software components in Oracle Solaris can
be found at https://www.oracle.com/downloads/opensource/solaris-source-
code-downloads.html.
This software was built from source available at
https://github.com/oracle/solaris-userland. The original community
source was downloaded from https://c-ares.haxx.se/download/c-
ares-1.17.2.tar.gz.
Further information about this software can be found on the open source
community website at https://c-ares.haxx.se/.
25 July 1998 ARES_SEND(3)