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/* $OpenBSD: res_search_async.c,v 1.8 2013/06/01 14:34:34 eric Exp $ */
/*
* Copyright (c) 2012 Eric Faurot <eric@openbsd.org>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <sys/types.h>
#include <sys/uio.h>
#include <arpa/nameser.h>
#include <err.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "asr.h"
#include "asr_private.h"
static int res_search_async_run(struct async *, struct async_res *);
/*
* Unlike res_query_async(), this function returns a valid packet only if
* h_errno is NETDB_SUCCESS.
*/
struct async *
res_search_async(const char *name, int class, int type, struct asr *asr)
{
struct asr_ctx *ac;
struct async *as;
DPRINT("asr: res_search_async(\"%s\", %i, %i)\n", name, class, type);
ac = asr_use_resolver(asr);
as = res_search_async_ctx(name, class, type, ac);
asr_ctx_unref(ac);
return (as);
}
struct async *
res_search_async_ctx(const char *name, int class, int type, struct asr_ctx *ac)
{
struct async *as;
char alias[MAXDNAME];
DPRINT("asr: res_search_async_ctx(\"%s\", %i, %i)\n", name, class,
type);
if (asr_hostalias(ac, name, alias, sizeof(alias)))
return res_query_async_ctx(alias, class, type, ac);
if ((as = async_new(ac, ASR_SEARCH)) == NULL)
goto err; /* errno set */
as->as_run = res_search_async_run;
if ((as->as.search.name = strdup(name)) == NULL)
goto err; /* errno set */
as->as.search.class = class;
as->as.search.type = type;
return (as);
err:
if (as)
async_free(as);
return (NULL);
}
#define HERRNO_UNSET -2
static int
res_search_async_run(struct async *as, struct async_res *ar)
{
int r;
char fqdn[MAXDNAME];
next:
switch (as->as_state) {
case ASR_STATE_INIT:
as->as.search.saved_h_errno = HERRNO_UNSET;
async_set_state(as, ASR_STATE_NEXT_DOMAIN);
break;
case ASR_STATE_NEXT_DOMAIN:
/*
* Reset flags to be able to identify the case in
* STATE_SUBQUERY.
*/
as->as_dom_flags = 0;
r = asr_iter_domain(as, as->as.search.name, fqdn, sizeof(fqdn));
if (r == -1) {
async_set_state(as, ASR_STATE_NOT_FOUND);
break;
}
if (r == 0) {
ar->ar_errno = EINVAL;
ar->ar_h_errno = NO_RECOVERY;
ar->ar_datalen = -1;
ar->ar_data = NULL;
async_set_state(as, ASR_STATE_HALT);
break;
}
as->as.search.subq = res_query_async_ctx(fqdn,
as->as.search.class, as->as.search.type, as->as_ctx);
if (as->as.search.subq == NULL) {
ar->ar_errno = errno;
if (errno == EINVAL)
ar->ar_h_errno = NO_RECOVERY;
else
ar->ar_h_errno = NETDB_INTERNAL;
ar->ar_datalen = -1;
ar->ar_data = NULL;
async_set_state(as, ASR_STATE_HALT);
break;
}
async_set_state(as, ASR_STATE_SUBQUERY);
break;
case ASR_STATE_SUBQUERY:
if ((r = async_run(as->as.search.subq, ar)) == ASYNC_COND)
return (ASYNC_COND);
as->as.search.subq = NULL;
if (ar->ar_h_errno == NETDB_SUCCESS) {
async_set_state(as, ASR_STATE_HALT);
break;
}
/*
* The original res_search() does this in the domain search
* loop, but only for ECONNREFUSED. I think we can do better
* because technically if we get an errno, it means
* we couldn't reach any nameserver, so there is no point
* in trying further.
*/
if (ar->ar_errno) {
async_set_state(as, ASR_STATE_HALT);
break;
}
free(ar->ar_data);
/*
* The original resolver does something like this.
*/
if (as->as_dom_flags & (ASYNC_DOM_NDOTS | ASYNC_DOM_ASIS))
as->as.search.saved_h_errno = ar->ar_h_errno;
if (as->as_dom_flags & ASYNC_DOM_DOMAIN) {
if (ar->ar_h_errno == NO_DATA)
as->as.search.flags |= ASYNC_NODATA;
else if (ar->ar_h_errno == TRY_AGAIN)
as->as.search.flags |= ASYNC_AGAIN;
}
async_set_state(as, ASR_STATE_NEXT_DOMAIN);
break;
case ASR_STATE_NOT_FOUND:
if (as->as.search.saved_h_errno != HERRNO_UNSET)
ar->ar_h_errno = as->as.search.saved_h_errno;
else if (as->as.search.flags & ASYNC_NODATA)
ar->ar_h_errno = NO_DATA;
else if (as->as.search.flags & ASYNC_AGAIN)
ar->ar_h_errno = TRY_AGAIN;
/*
* Else, we got the ar_h_errno value set by res_query_async()
* for the last domain.
*/
ar->ar_datalen = -1;
ar->ar_data = NULL;
async_set_state(as, ASR_STATE_HALT);
break;
case ASR_STATE_HALT:
return (ASYNC_DONE);
default:
ar->ar_errno = EOPNOTSUPP;
ar->ar_h_errno = NETDB_INTERNAL;
async_set_state(as, ASR_STATE_HALT);
break;
}
goto next;
}
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