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checkpoint resolver code

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This commit is contained in:
Bob Halley
1999-06-28 23:37:54 +00:00
parent ce07d4eaac
commit 49dd071153
3 changed files with 1024 additions and 2 deletions
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4
lib/dns/Makefile.in
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@@ -36,12 +36,12 @@ LIBS = @LIBS@
OBJS = callbacks.o compress.o db.o dbiterator.o dbtable.o dispatch.o \
lib.o master.o message.o name.o rbt.o rbtdb.o rbtdb64.o \
rdata.o rdatalist.o rdataset.o rdatasetiter.o rdataslab.o \
result.o version.o masterdump.o time.o ttl.o
resolver.o result.o version.o masterdump.o time.o ttl.o
OSRC = callbacks.c compress.c db.c dbiterator.c dbtable.c dispatch.c \
lib.c master.c name.c rbt.c rbtdb.c rbtdb64.c \
rdata.c rdatalist.c rdataset.c rdatasetiter.c rdataslab.c \
result.c version.c masterdump.c time.c ttl.c
resolver.c result.c version.c masterdump.c time.c ttl.c
SUBDIRS = include
TARGETS = include/dns/enumtype.h include/dns/enumclass.h \

104
lib/dns/include/dns/resolver.h Normal file
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@@ -0,0 +1,104 @@
/*
* Copyright (C) 1999 Internet Software Consortium.
*
* 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 INTERNET SOFTWARE CONSORTIUM DISCLAIMS
* ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
* CONSORTIUM 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.
*/
#ifndef DNS_RESOLVER_H
#define DNS_RESOLVER_H 1
/*****
***** Module Info
*****/
/*
* DNS Resolver
*
* XXX <TBS> XXX
*
* MP:
* The module ensures appropriate synchronization of data structures it
* creates and manipulates.
*
* Reliability:
* No anticipated impact.
*
* Resources:
* <TBS>
*
* Security:
* No anticipated impact.
*
* Standards:
* RFCs: 1034, 1035, 2181, <TBS>
* Drafts: <TBS>
*/
#include <isc/lang.h>
#include <isc/event.h>
#include <dns/types.h>
#include <dns/result.h>
ISC_LANG_BEGINDECLS
struct dns_fetch {
unsigned int magic;
dns_resolver_t * res;
void * private;
unsigned int tag;
ISC_LINK(struct dns_fetch) link;
};
#define DNS_FETCH_MAGIC 0x46746368U /* Ftch */
#define DNS_FETCH_VALID(fetch) ((fetch) != NULL && \
(fetch)->magic == DNS_FETCH_MAGIC)
typedef struct dns_fetchdoneevent {
ISC_EVENT_COMMON(struct dns_fetchdoneevent);
dns_result_t result;
} dns_fetchdoneevent_t;
#define DNS_FETCHOPT_TCP 0x01
#define DNS_FETCHOPT_UNSHARED 0x02
dns_result_t
dns_resolver_create(isc_mem_t *mctx,
isc_taskmgr_t *taskmgr, unsigned int ntasks,
isc_timermgr_t *timermgr,
dns_rdataclass_t rdclass,
dns_dispatch_t *dispatcher,
dns_resolver_t **resp);
void
dns_resolver_attach(dns_resolver_t *source, dns_resolver_t **targetp);
void
dns_resolver_detach(dns_resolver_t **resp);
dns_result_t
dns_resolver_createfetch(dns_resolver_t *res, dns_name_t *name,
dns_rdatatype_t type,
dns_delegation_t *delegation,
dns_forwarders_t *forwarders,
unsigned int options, isc_task_t *task,
isc_taskaction_t action, void *arg,
dns_fetch_t **fetchp);
void
dns_resolver_destroyfetch(dns_fetch_t **fetchp, isc_task_t *task);
ISC_LANG_ENDDECLS
#endif /* DNS_RESOLVER_H */

918
lib/dns/resolver.c Normal file
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@@ -0,0 +1,918 @@
#include <isc/assertions.h>
#include <isc/result.h>
#include <isc/timer.h>
#include <isc/mutex.h>
#include <isc/event.h>
#include <isc/task.h>
#include <isc/stdtime.h>
#include <dns/types.h>
#include <dns/result.h>
#include <dns/name.h>
#include <dns/events.h>
#include <dns/message.h>
#include <dns/dispatch.h>
#include <dns/resolver.h>
#include "../isc/util.h" /* XXX */
#define DNS_RESOLVER_TRACE
#ifdef DNS_RESOLVER_TRACE
#define RTRACE(m) printf("res %p: %s\n", res, (m))
#define RRTRACE(r, m) printf("res %p: %s\n", (r), (m))
#define FCTXTRACE(m) printf("fctx %p: %s\n", fctx, (m))
#define FTRACE(m) printf("fetch %p (res %p fctx %p tag %u): %s\n", \
fetch, fetch->res, fetch->private, fetch->tag, \
(m))
#else
#define RTRACE(m)
#define RRTRACE(r, m)
#define FCTXTRACE(m)
#define FTRACE(m)
#endif
typedef struct query {
dns_messageid_t id;
ISC_LINK(struct query) link;
} resquery_t;
typedef enum {
fetchstate_init = 0,
fetchstate_active,
fetchstate_exiting,
fetchstate_done
} fetchstate;
typedef struct fetchctx {
unsigned int magic;
fetchstate state;
dns_resolver_t * res;
unsigned int references;
unsigned int locknum;
dns_name_t name;
dns_rdatatype_t type; /* multiple types??? */
unsigned int options;
/* Locked by lock. */
isc_timer_t * timer;
isc_time_t expires;
isc_interval_t interval;
unsigned int next_tag;
ISC_LIST(dns_fetchdoneevent_t) events;
isc_event_t start_event;
dns_dispatch_t * dispatcher;
dns_message_t * message;
ISC_LIST(resquery_t) queries;
ISC_LINK(struct fetchctx) link;
} fetchctx_t;
#define FCTX_MAGIC 0x46212121U /* F!!! */
#define VALID_FCTX(fctx) ((fctx) != NULL && \
(fctx)->magic == FCTX_MAGIC)
struct dns_resolver {
/* Unlocked */
unsigned int magic;
isc_mem_t * mctx;
isc_mutex_t lock;
dns_rdataclass_t rdclass;
isc_timermgr_t * timermgr;
/* Locked by lock. */
unsigned int references;
isc_boolean_t exiting;
dns_dispatch_t * shared_dispatcher;
unsigned int ntasks;
unsigned int next_task;
isc_task_t ** tasks;
ISC_LIST(fetchctx_t) fctxs;
};
#define RES_MAGIC 0x52657321U /* Res! */
#define VALID_RESOLVER(res) ((res) != NULL && \
(res)->magic == RES_MAGIC)
static void destroy(dns_resolver_t *res);
/*
* Internal fetch routines. Caller must be holding the proper lock.
*/
static void
fctx_done(fetchctx_t *fctx, dns_result_t result) {
dns_fetchdoneevent_t *event, *next_event;
isc_task_t *task;
isc_result_t iresult;
/*
* The caller must be holding the proper lock.
*/
FCTXTRACE("done");
REQUIRE(fctx->state == fetchstate_active);
fctx->state = fetchstate_done;
for (event = ISC_LIST_HEAD(fctx->events);
event != NULL;
event = next_event) {
next_event = ISC_LIST_NEXT(event, link);
task = event->sender;
event->sender = fctx;
event->result = result;
iresult = isc_task_send(task, (isc_event_t **)&event);
if (iresult != ISC_R_SUCCESS) {
UNEXPECTED_ERROR(__FILE__, __LINE__,
"isc_task_send(): %s",
isc_result_totext(iresult));
isc_event_free((isc_event_t **)&event);
}
isc_task_detach(&task);
}
ISC_LIST_INIT(fctx->events);
}
static dns_result_t
fctx_sendquery(fetchctx_t *fctx) {
resquery_t *query;
FCTXTRACE("sendquery");
query = isc_mem_get(fctx->res->mctx, sizeof *query);
if (query == NULL)
return (DNS_R_NOMEMORY);
ISC_LIST_APPEND(fctx->queries, query, link);
/* XXXRTH do the rest of the work... */
return (DNS_R_SUCCESS);
}
static void
fctx_cancelqueries(fetchctx_t *fctx) {
resquery_t *query, *next_query;
FCTXTRACE("cancelqueries");
for (query = ISC_LIST_HEAD(fctx->queries);
query != NULL;
query = next_query) {
next_query = ISC_LIST_NEXT(query, link);
/* XXXRTH do the rest of the work... */
isc_mem_put(fctx->res->mctx, query, sizeof *query);
}
ISC_LIST_INIT(fctx->queries);
}
static void
fctx_restart(fetchctx_t *fctx) {
isc_result_t iresult;
dns_result_t result;
/*
* Caller must be holding the fetch's lock.
*/
REQUIRE(fctx->state = fetchstate_active);
FCTXTRACE("restart");
iresult = isc_timer_reset(fctx->timer, isc_timertype_once,
&fctx->expires, &fctx->interval,
ISC_FALSE);
if (iresult != ISC_R_SUCCESS) {
UNEXPECTED_ERROR(__FILE__, __LINE__,
"isc_timer_reset(): %s",
isc_result_totext(iresult));
fctx_done(fctx, DNS_R_UNEXPECTED);
}
result = fctx_sendquery(fctx);
if (result != DNS_R_SUCCESS)
fctx_done(fctx, result);
}
static void
fctx_destroy(fetchctx_t *fctx) {
REQUIRE(VALID_FCTX(fctx));
REQUIRE(fctx->state == fetchstate_done);
REQUIRE(ISC_LIST_EMPTY(fctx->events));
REQUIRE(ISC_LIST_EMPTY(fctx->queries));
FCTXTRACE("destroy");
isc_timer_detach(&fctx->timer);
dns_name_free(&fctx->name, fctx->res->mctx);
isc_mem_put(fctx->res->mctx, fctx, sizeof *fctx);
}
/*
* Fetch event handlers.
*/
static void
fctx_timeout(isc_task_t *task, isc_event_t *event) {
fetchctx_t *fctx = event->arg;
REQUIRE(VALID_FCTX(fctx));
(void)task; /* Keep compiler quiet. */
FCTXTRACE("timeout");
LOCK(&fctx->res->lock);
INSIST(fctx->state == fetchstate_active);
if (event->type == ISC_TIMEREVENT_LIFE) {
fctx_cancelqueries(fctx);
fctx_done(fctx, DNS_R_TIMEDOUT);
} else {
/*
* We could cancel the running queries here, or we could let
* them keep going. Right now we choose the latter...
*/
fctx_restart(fctx);
}
UNLOCK(&fctx->res->lock);
isc_event_free(&event);
}
static void
fctx_start(isc_task_t *task, isc_event_t *event) {
fetchctx_t *fctx = event->arg;
isc_boolean_t need_fctx_destroy = ISC_FALSE;
isc_boolean_t need_resolver_destroy = ISC_FALSE;
dns_resolver_t *res;
REQUIRE(VALID_FCTX(fctx));
res = fctx->res;
(void)task; /* Keep compiler quiet. */
FCTXTRACE("start");
LOCK(&res->lock);
INSIST(fctx->state == fetchstate_init ||
fctx->state == fetchstate_exiting);
if (fctx->state == fetchstate_init) {
fctx->state = fetchstate_active;
fctx_restart(fctx);
} else {
fctx->state = fetchstate_done;
need_fctx_destroy = ISC_TRUE;
if (res->exiting && ISC_LIST_EMPTY(res->fctxs))
need_resolver_destroy = ISC_TRUE;
}
UNLOCK(&res->lock);
if (need_fctx_destroy)
fctx_destroy(fctx);
if (need_resolver_destroy)
destroy(res);
}
/*
* Fetch Creation, Joining, and Cancelation.
*/
static inline dns_result_t
fctx_join(fetchctx_t *fctx, isc_task_t *task, isc_taskaction_t action,
void *arg, dns_fetch_t *fetch)
{
isc_task_t *clone;
dns_fetchdoneevent_t *event;
FCTXTRACE("join");
/*
* We store the task we're going to send this event to in the
* sender field. We'll make the fetch the sender when we actually
* send the event.
*/
clone = NULL;
isc_task_attach(task, &clone);
event = (dns_fetchdoneevent_t *)
isc_event_allocate(fctx->res->mctx, clone,
DNS_EVENT_FETCHDONE,
action, arg, sizeof *event);
if (event == NULL)
return (DNS_R_NOMEMORY);
event->result = DNS_R_SUCCESS;
event->tag = fctx->next_tag++;
INSIST(fctx->next_tag != 0);
/*
* XXX other event initialization here.
*/
ISC_LIST_APPEND(fctx->events, event, link);
fctx->references++;
fetch->magic = DNS_FETCH_MAGIC;
fetch->res = fctx->res;
fetch->private = fctx;
fetch->tag = event->tag;
ISC_LINK_INIT(fetch, link);
return (DNS_R_SUCCESS);
}
static dns_result_t
fctx_create(dns_resolver_t *res, dns_name_t *name, dns_rdatatype_t type,
unsigned int options,
isc_task_t *worker, isc_task_t *task, isc_taskaction_t action,
void *arg, dns_fetch_t *fetch)
{
fetchctx_t *fctx;
dns_result_t result = DNS_R_SUCCESS;
isc_result_t iresult;
isc_event_t *event;
isc_interval_t interval;
fctx = isc_mem_get(res->mctx, sizeof *fctx);
if (fctx == NULL)
return (DNS_R_NOMEMORY);
FCTXTRACE("create");
result = dns_name_dup(name, res->mctx, NULL, &fctx->name);
if (result != DNS_R_SUCCESS)
goto cleanup_fetch;
fctx->type = type;
fctx->options = options;
fctx->res = res;
fctx->references = 0;
fctx->locknum = 0;
fctx->state = fetchstate_init;
fctx->dispatcher = NULL; /* XXX */
fctx->next_tag = 1;
ISC_LIST_INIT(fctx->queries);
fctx->message = NULL;
result = dns_message_create(res->mctx, &fctx->message,
DNS_MESSAGE_INTENTPARSE);
if (result != DNS_R_SUCCESS)
goto cleanup_name;
/*
* Compute an expiration time for the entire fetch.
*/
isc_interval_set(&interval, 10, 0); /* XXXRTH constant */
iresult = isc_time_nowplusinterval(&fctx->expires, &interval);
if (iresult != ISC_R_SUCCESS) {
UNEXPECTED_ERROR(__FILE__, __LINE__,
"isc_stdtime_get: %s",
isc_result_totext(iresult));
result = DNS_R_UNEXPECTED;
goto cleanup_message;
}
/*
* XXX Retry interval initialization. Should be setup by the
* transmission strategy routine (when we have one).
*/
isc_interval_set(&fctx->interval, 1, 500000000);
/*
* Create an inactive timer. It will be made active when the fetch
* is actually started.
*/
iresult = isc_timer_create(res->timermgr, isc_timertype_inactive,
NULL, NULL,
worker, fctx_timeout,
fctx, &fctx->timer);
if (iresult != ISC_R_SUCCESS) {
UNEXPECTED_ERROR(__FILE__, __LINE__,
"isc_timer_create: %s",
isc_result_totext(iresult));
result = DNS_R_UNEXPECTED;
goto cleanup_message;
}
ISC_LIST_INIT(fctx->events);
result = fctx_join(fctx, task, action, arg, fetch);
if (result != DNS_R_SUCCESS)
goto cleanup_timer;
ISC_LINK_INIT(fctx, link);
fctx->magic = FCTX_MAGIC;
/*
* The fetch is now ready to go. We send the start event to its
* task to get the ball rolling.
*
* XXX we should really send this event from dns_resolver_fetch(),
* after we've unlocked the fetch's lock, otherwise the other task
* could well block on the lock we're about to release.
*/
event = &fctx->start_event;
ISC_EVENT_INIT(event, sizeof *event, 0, 0, DNS_EVENT_FETCH,
fctx_start, fctx, (void *)fctx_create, NULL, NULL);
iresult = isc_task_send(worker, &event);
if (iresult != ISC_R_SUCCESS) {
UNEXPECTED_ERROR(__FILE__, __LINE__,
"isc_task_send: %s",
isc_result_totext(iresult));
result = DNS_R_UNEXPECTED;
goto cleanup_timer;
}
return (DNS_R_SUCCESS);
cleanup_timer:
isc_timer_detach(&fctx->timer);
cleanup_message:
dns_message_destroy(&fctx->message);
cleanup_name:
dns_name_free(&fctx->name, res->mctx);
cleanup_fetch:
isc_mem_put(res->mctx, fctx, sizeof *fctx);
return (result);
}
static void
fctx_cancel(fetchctx_t *fctx) {
isc_result_t iresult;
FCTXTRACE("cancel");
if (fctx->state != fetchstate_done) {
fctx_cancelqueries(fctx);
iresult = isc_timer_reset(fctx->timer, isc_timertype_inactive,
NULL, NULL, ISC_TRUE);
if (iresult != ISC_R_SUCCESS)
UNEXPECTED_ERROR(__FILE__, __LINE__,
"isc_timer_reset(): %s",
isc_result_totext(iresult));
fctx_done(fctx, DNS_R_CANCELED);
}
}
/*
* Handle Responses
*/
static inline dns_result_t
same_question(fetchctx_t *fctx) {
dns_result_t result;
dns_message_t *message = fctx->message;
dns_name_t *name;
dns_rdataset_t *rdataset;
/*
* Caller must be holding the fctx lock.
*/
/*
* XXXRTH Currently we support only one question.
*/
if (message->counts[DNS_SECTION_QUESTION] != 1)
return (DNS_R_FORMERR);
result = dns_message_firstname(message, DNS_SECTION_QUESTION);
if (result != DNS_R_SUCCESS)
return (result);
name = NULL;
dns_message_currentname(message, DNS_SECTION_QUESTION, &name);
rdataset = ISC_LIST_HEAD(name->list);
INSIST(rdataset != NULL);
INSIST(ISC_LIST_NEXT(rdataset, link) == NULL);
if (fctx->type != rdataset->type ||
fctx->res->rdclass != rdataset->rdclass ||
!dns_name_equal(&fctx->name, name))
return (DNS_R_FORMERR);
return (DNS_R_SUCCESS);
}
static void
fctx_response(isc_task_t *task, isc_event_t *event) {
dns_result_t result;
fetchctx_t *fctx = event->arg;
dns_dispatchevent_t *devent = (dns_dispatchevent_t *)event;
isc_boolean_t bad_sender = ISC_FALSE;
dns_message_t *message;
REQUIRE(VALID_FCTX(fctx));
REQUIRE(event->type == DNS_EVENT_DISPATCH);
LOCK(&fctx->res->lock);
INSIST(fctx->state == fetchstate_active);
message = fctx->message;
result = dns_message_parse(message, &devent->buffer);
if (result != DNS_R_SUCCESS) {
switch (result) {
case DNS_R_FORMERR:
case DNS_R_UNEXPECTEDEND:
bad_sender = ISC_TRUE;
break;
case DNS_R_MOREDATA:
result = DNS_R_NOTIMPLEMENTED;
break;
}
goto done;
}
INSIST((message->flags & DNS_MESSAGEFLAG_QR) != 0);
/*
* INSIST() that the message comes from the place we sent it to,
* since the dispatch code should ensure this.
*
* INSIST() that the message id is correct (this should also be
* ensured by the dispatch code).
*/
/*
* Is it a query response?
*/
if (message->opcode != dns_opcode_query) {
/* XXXRTH Log */
bad_sender = ISC_TRUE;
goto done;
}
/*
* Is the remote server broken, or does it dislike us?
*/
if (message->rcode != dns_rcode_noerror &&
message->rcode != dns_rcode_nxdomain) {
bad_sender = ISC_TRUE;
/*
* XXXRTH If we want to catch a FORMERR caused by an EDNS0
* OPT RR, this is the place to do it.
*/
goto done;
}
/*
* Does the it answer the question we asked?
*/
result = same_question(fctx);
if (result != DNS_R_SUCCESS) {
/* XXXRTH Log */
if (result == DNS_R_FORMERR)
bad_sender = ISC_TRUE;
goto done;
}
result = DNS_R_SUCCESS;
done:
/*
* XXXRTH Record round-trip statistics here.
*/
if (bad_sender) {
/*
* XXXRTH We will mark the sender as bad here instead
* of doing the printf().
*/
printf("bad sender\n");
/*
* Keep trying.
*/
fctx_restart(fctx);
} else {
/*
* All is well, or we got an error fatal to the fetch.
* In either case, we're done.
*/
fctx_done(fctx, result);
}
UNLOCK(&fctx->res->lock);
isc_event_free(&event);
}
/***
*** Resolver Methods
***/
static void
destroy(dns_resolver_t *res) {
unsigned int i;
REQUIRE(res->exiting);
REQUIRE(res->references == 0);
REQUIRE(ISC_LIST_EMPTY(res->fctxs));
RTRACE("destroy");
isc_mutex_destroy(&res->lock);
for (i = 0; i < res->ntasks; i++) {
isc_task_shutdown(res->tasks[i]);
isc_task_detach(&res->tasks[i]);
}
isc_mem_put(res->mctx, res->tasks,
res->ntasks * sizeof (isc_task_t *));
res->magic = 0;
isc_mem_put(res->mctx, res, sizeof *res);
}
dns_result_t
dns_resolver_create(isc_mem_t *mctx,
isc_taskmgr_t *taskmgr, unsigned int ntasks,
isc_timermgr_t *timermgr,
dns_rdataclass_t rdclass,
dns_dispatch_t *dispatcher,
dns_resolver_t **resp)
{
dns_resolver_t *res;
dns_result_t result = DNS_R_SUCCESS;
isc_result_t iresult;
unsigned int i, tasks_created = 0;
REQUIRE(resp != NULL && *resp == NULL);
REQUIRE(ntasks > 0);
res = isc_mem_get(mctx, sizeof *res);
if (res == NULL)
return (DNS_R_NOMEMORY);
RTRACE("create");
res->mctx = mctx;
res->rdclass = rdclass;
res->timermgr = timermgr;
res->ntasks = ntasks;
res->next_task = 0;
res->shared_dispatcher = dispatcher; /* XXXRTH: attach! */
res->tasks = isc_mem_get(mctx, ntasks * sizeof (isc_task_t *));
if (res->tasks == NULL) {
result = DNS_R_NOMEMORY;
goto cleanup_res;
}
for (i = 0; i < ntasks; i++) {
res->tasks[i] = NULL;
iresult = isc_task_create(taskmgr, mctx, 0, &res->tasks[i]);
if (iresult != ISC_R_SUCCESS) {
UNEXPECTED_ERROR(__FILE__, __LINE__,
"isc_task_create() failed: %s",
isc_result_totext(iresult));
result = DNS_R_UNEXPECTED;
goto cleanup_tasks;
}
tasks_created++;
}
res->references = 1;
res->exiting = ISC_FALSE;
iresult = isc_mutex_init(&res->lock);
if (iresult != ISC_R_SUCCESS) {
UNEXPECTED_ERROR(__FILE__, __LINE__,
"isc_mutex_init() failed: %s",
isc_result_totext(iresult));
result = DNS_R_UNEXPECTED;
goto cleanup_tasks;
}
ISC_LIST_INIT(res->fctxs);
res->magic = RES_MAGIC;
*resp = res;
return (DNS_R_SUCCESS);
cleanup_tasks:
for (i = 0; i < tasks_created; i++) {
isc_task_shutdown(res->tasks[i]);
isc_task_detach(&res->tasks[i]);
}
isc_mem_put(mctx, res->tasks, res->ntasks * sizeof (isc_task_t *));
cleanup_res:
isc_mem_put(mctx, res, sizeof *res);
return (result);
}
void
dns_resolver_attach(dns_resolver_t *source, dns_resolver_t **targetp) {
REQUIRE(VALID_RESOLVER(source));
REQUIRE(targetp != NULL && *targetp == NULL);
RRTRACE(source, "attach");
LOCK(&source->lock);
REQUIRE(!source->exiting);
INSIST(source->references > 0);
source->references++;
INSIST(source->references != 0);
UNLOCK(&source->lock);
*targetp = source;
}
void
dns_resolver_detach(dns_resolver_t **resp) {
dns_resolver_t *res;
isc_boolean_t need_destroy = ISC_FALSE;
fetchctx_t *fctx;
REQUIRE(resp != NULL);
res = *resp;
REQUIRE(VALID_RESOLVER(res));
RTRACE("detach");
LOCK(&res->lock);
INSIST(res->references > 0);
res->references--;
if (res->references == 0) {
RTRACE("exiting");
res->exiting = ISC_TRUE;
for (fctx = ISC_LIST_HEAD(res->fctxs);
fctx != NULL;
fctx = ISC_LIST_NEXT(fctx, link))
fctx_cancel(fctx);
if (ISC_LIST_EMPTY(res->fctxs))
need_destroy = ISC_TRUE;
}
UNLOCK(&res->lock);
if (need_destroy)
destroy(res);
*resp = NULL;
}
static inline isc_boolean_t
fctx_match(fetchctx_t *fctx, dns_name_t *name, dns_rdatatype_t type,
unsigned int options)
{
if (fctx->type != type || fctx->options != options)
return (ISC_FALSE);
return (dns_name_equal(&fctx->name, name));
}
dns_result_t
dns_resolver_createfetch(dns_resolver_t *res, dns_name_t *name,
dns_rdatatype_t type,
dns_delegation_t *delegation,
dns_forwarders_t *forwarders,
unsigned int options, isc_task_t *task,
isc_taskaction_t action, void *arg,
dns_fetch_t **fetchp)
{
dns_fetch_t *fetch;
fetchctx_t *fctx = NULL;
dns_result_t result;
isc_task_t *worker;
(void)delegation;
(void)forwarders;
REQUIRE(VALID_RESOLVER(res));
REQUIRE(fetchp != NULL && *fetchp == NULL);
/*
* We require !res->exiting, since if it were exiting, that would
* mean that the reference count was wrong!
*/
REQUIRE(!res->exiting);
RTRACE("createfetch");
/* XXXRTH */
if ((options & DNS_FETCHOPT_TCP) != 0)
return (DNS_R_NOTIMPLEMENTED);
fetch = isc_mem_get(res->mctx, sizeof *fetch);
if (fetch == NULL)
return (DNS_R_NOMEMORY);
LOCK(&res->lock);
/*
* XXXRTH This is for correctness, and doesn't represent the final
* way of assigning tasks, or the final form of the fetch table.
*/
worker = res->tasks[res->next_task];
res->next_task++;
if (res->next_task == res->ntasks)
res->next_task = 0;
if ((options & DNS_FETCHOPT_UNSHARED) == 0) {
for (fctx = ISC_LIST_HEAD(res->fctxs);
fctx != NULL;
fctx = ISC_LIST_NEXT(fctx, link)) {
if (fctx_match(fctx, name, type, options))
break;
}
}
if (fctx == NULL || fctx->state == fetchstate_done) {
result = fctx_create(res,
name, type, options,
worker,
task, action, arg,
fetch);
if (result == DNS_R_SUCCESS) {
fctx = fetch->private;
ISC_LIST_APPEND(res->fctxs, fctx, link);
}
} else
result = fctx_join(fctx, task, action, arg, fetch);
UNLOCK(&res->lock);
if (result == DNS_R_SUCCESS) {
FTRACE("created");
*fetchp = fetch;
} else
isc_mem_put(res->mctx, fetch, sizeof *fetch);
return (result);
}
void
dns_resolver_destroyfetch(dns_fetch_t **fetchp, isc_task_t *task) {
dns_fetch_t *fetch;
dns_fetchdoneevent_t *event, *next_event;
fetchctx_t *fctx;
dns_resolver_t *res;
isc_boolean_t need_fctx_destroy = ISC_FALSE;
isc_boolean_t need_resolver_destroy = ISC_FALSE;
isc_task_t *etask;
/*
* XXXRTH We could make it so that even if all the clients detach
* from the fetch, the fctx keeps going. Perhaps this should be
* a resolver option? Right now if they all go away the fctx will
* be destroyed too.
*/
REQUIRE(fetchp != NULL);
fetch = *fetchp;
REQUIRE(DNS_FETCH_VALID(fetch));
res = fetch->res;
fctx = fetch->private;
FTRACE("destroyfetch");
LOCK(&res->lock);
event = NULL;
if (fctx->state != fetchstate_done) {
for (event = ISC_LIST_HEAD(fctx->events);
event != NULL;
event = next_event) {
next_event = ISC_LIST_NEXT(event, link);
if (event->tag == fetch->tag) {
ISC_LIST_UNLINK(fctx->events, event, link);
FTRACE("found");
break;
}
}
} else if (task != NULL)
(void)isc_task_purge(task, fctx, DNS_EVENT_FETCHDONE,
fetch->tag);
INSIST(fctx->references > 0);
fctx->references--;
if (fctx->references == 0) {
ISC_LIST_UNLINK(res->fctxs, fctx, link);
if (fctx->state == fetchstate_init) {
/*
* The fctx is still initializing, which means that
* the start event either hasn't been delivered, or
* is being processed right now, but is blocked waiting
* for the lock.
*
* Rather than try to purge the event, we simply
* wait for it to happen, deferring further destruction
* until it has been processed.
*/
fctx->state = fetchstate_exiting;
} else {
need_fctx_destroy = ISC_TRUE;
if (res->exiting && ISC_LIST_EMPTY(res->fctxs))
need_resolver_destroy = ISC_TRUE;
}
}
UNLOCK(&res->lock);
if (event != NULL) {
etask = event->sender;
isc_task_detach(&etask);
isc_event_free((isc_event_t **)&event);
}
if (need_fctx_destroy)
fctx_destroy(fctx);
if (need_resolver_destroy)
destroy(res);
isc_mem_put(res->mctx, fetch, sizeof *fetch);
*fetchp = NULL;
}