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74a169575d
curl-curl/lib/asyn.h
Stefan Eissing 2b3dfb4ad4
lib: make resolving HTTPS DNS records reliable: 
- allow to specify when they are wanted on starting a resolve
- match dns cache entries accordingly. An entry which never
  tried to get HTTPS-RRs is no answer for a resolve that wants
  it.
- fix late arrivals of resolve answers to match the "async"
  records that started them - if it still exists.
- provide for multiple "async" resolves in a transfer at the
  same time. We may need to resolve an IP interface while the
  main connection resolve has not finished yet.
- allow lookup of HTTPS-RR information as soon as it is
  available, even if A/AAAA queries are still ongoing.

For this, the "async" infrastructure is changed:

- Defined bits for DNS queries `CURL_DNSQ_A`, `CURL_DNSQ_AAAA`
  and `CURL_DNSQ_HTTPS`. These replace `ip_version` which says
  nothing about HTTPS.
  Use them in dns cache entries for matching.
- enhance the `async->id` to be a unique `uint32_t` for
  resolves inside one multi. This is weak, as the id may
  wrap around. However it is combined with the `mid` of
  the easy handle, making collisions highly unlikely.
  `data->state.async` is only accessed in few places where
  the mid/async-id match is performed.
- vtls: for ECH supporting TLS backends (openssl, rustls, wolfssl),
  retrieve the HTTPS-RR information from the dns connection filter.
  Delay the connect if the HTTPS-RR is needed, but has not
  been resolved yet.

The implementation of all this is complete for the threaded
resolver. c-ares resolver and DoH do not take advantage of
all new async features yet. To be done in separate PRs.

Details:

c-ares: cleanup settings and initialisation. Any ares channel
is only being created on starting a resolve and propagating
operations in setopt.c to the channel are not helpful.

Changed threaded+ares pollset handling so that they do not
overwrite each others `ASYNC_NAME` timeouts.

Add trace name 'threads' for tracing thread queue and
pool used by threaded resolver.

Closes #21175
2026-04-01 15:36:31 +02:00

271 lines
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#ifndef HEADER_CURL_ASYN_H
#define HEADER_CURL_ASYN_H
/***************************************************************************
* _ _ ____ _
* Project ___| | | | _ \| |
* / __| | | | |_) | |
* | (__| |_| | _ <| |___
* \___|\___/|_| \_\_____|
*
* Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
*
* This software is licensed as described in the file COPYING, which
* you should have received as part of this distribution. The terms
* are also available at https://curl.se/docs/copyright.html.
*
* You may opt to use, copy, modify, merge, publish, distribute and/or sell
* copies of the Software, and permit persons to whom the Software is
* furnished to do so, under the terms of the COPYING file.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
* SPDX-License-Identifier: curl
*
***************************************************************************/
#include "curl_setup.h"
#if defined(USE_HTTPSRR) && defined(USE_ARES)
#include "httpsrr.h"
#endif
struct Curl_easy;
struct Curl_dns_entry;
struct Curl_resolv_async;
struct Curl_multi;
struct easy_pollset;
#ifdef CURLRES_ASYNCH
#include "curl_addrinfo.h"
struct hostent;
struct connectdata;
struct easy_pollset;
#if defined(USE_RESOLV_ARES) && defined(USE_RESOLV_THREADED)
#error cannot have both USE_RESOLV_ARES and USE_RESOLV_THREADED defined
#endif
/*
* This header defines all functions in the internal asynch resolver interface.
* All asynch resolvers need to provide these functions.
* asyn-ares.c and asyn-thread.c are the current implementations of asynch
* resolver backends.
*/
/*
* Curl_async_global_init()
*
* Called from curl_global_init() to initialize global resolver environment.
* Returning anything else than CURLE_OK fails curl_global_init().
*/
int Curl_async_global_init(void);
/*
* Curl_async_global_cleanup()
* Called from curl_global_cleanup() to destroy global resolver environment.
*/
void Curl_async_global_cleanup(void);
/*
* Curl_async_getaddrinfo() - when using this resolver
*
* Returns name information about the given hostname and port number. If
* successful, the 'hostent' is returned and the fourth argument will point to
* memory we need to free after use. That memory *MUST* be freed with
* Curl_freeaddrinfo(), nothing else.
*
* Each resolver backend must of course make sure to return data in the
* correct format to comply with this.
*/
CURLcode Curl_async_getaddrinfo(struct Curl_easy *data,
struct Curl_resolv_async *async);
const struct Curl_addrinfo *
Curl_async_get_ai(struct Curl_easy *data,
struct Curl_resolv_async *async,
int ai_family, unsigned int index);
#ifdef USE_HTTPSRR
const struct Curl_https_rrinfo *
Curl_async_get_https(struct Curl_easy *data,
struct Curl_resolv_async *async);
bool Curl_async_knows_https(struct Curl_easy *data,
struct Curl_resolv_async *async);
#endif /* USE_HTTPSRR */
#ifdef USE_ARES
/* common functions for c-ares and threaded resolver with HTTPSRR */
#include <ares.h>
CURLcode Curl_ares_pollset(struct Curl_easy *data,
ares_channel channel,
struct easy_pollset *ps);
timediff_t Curl_ares_timeout_ms(struct Curl_easy *data,
struct Curl_resolv_async *async,
ares_channel channel);
int Curl_ares_perform(ares_channel channel, timediff_t timeout_ms);
#endif
#ifdef USE_RESOLV_ARES
/* async resolving implementation using c-ares alone */
struct async_ares_ctx {
ares_channel channel;
struct Curl_addrinfo *temp_ai; /* intermediary result while fetching c-ares
parts */
int ares_status; /* ARES_SUCCESS, ARES_ENOTFOUND, etc. */
CURLcode result; /* CURLE_OK or error handling response */
struct curltime happy_eyeballs_dns_time; /* when this timer started, or 0 */
#ifdef USE_HTTPSRR
struct Curl_https_rrinfo hinfo;
#endif
};
void Curl_async_ares_shutdown(struct Curl_easy *data,
struct Curl_resolv_async *async);
void Curl_async_ares_destroy(struct Curl_easy *data,
struct Curl_resolv_async *async);
#endif /* USE_RESOLV_ARES */
#ifdef USE_RESOLV_THREADED
struct async_thrdd_item;
/* Context for threaded resolver */
struct async_thrdd_ctx {
struct async_thrdd_item *res_A; /* ipv4 result */
struct async_thrdd_item *res_AAAA; /* ipv6 result */
#if defined(USE_HTTPSRR) && defined(USE_ARES)
struct {
ares_channel channel;
struct Curl_https_rrinfo hinfo;
} rr;
#endif
};
void Curl_async_thrdd_shutdown(struct Curl_easy *data,
struct Curl_resolv_async *async);
void Curl_async_thrdd_destroy(struct Curl_easy *data,
struct Curl_resolv_async *async);
CURLcode Curl_async_thrdd_multi_init(struct Curl_multi *multi,
uint32_t min_threads,
uint32_t max_threads,
uint32_t idle_time_ms);
void Curl_async_thrdd_multi_destroy(struct Curl_multi *multi, bool join);
void Curl_async_thrdd_multi_process(struct Curl_multi *multi);
CURLcode Curl_async_thrdd_multi_set_props(struct Curl_multi *multi,
uint32_t min_threads,
uint32_t max_threads,
uint32_t idle_time_ms);
#endif /* USE_RESOLV_THREADED */
#ifndef CURL_DISABLE_DOH
struct doh_probes;
#endif
/*
* Curl_async_await()
*
* Waits for a resolve to finish. This function should be avoided since using
* this risk getting the multi interface to "hang".
*
* On return 'entry' is assigned the resolved dns (CURLE_OK or NULL otherwise.
*
* Returns CURLE_COULDNT_RESOLVE_HOST if the host was not resolved,
* CURLE_OPERATION_TIMEDOUT if a time-out occurred, or other errors.
*/
CURLcode Curl_async_await(struct Curl_easy *data, uint32_t resolv_id,
struct Curl_dns_entry **pdns);
/*
* Take the result of an async resolve operation.
* Returns CURLE_OK with `*pdns` != NULL, CURLE_AGAIN while still
* ongoing or an error code for a failed resolve.
*/
CURLcode Curl_async_take_result(struct Curl_easy *data,
struct Curl_resolv_async *async,
struct Curl_dns_entry **pdns);
/* Curl_async_pollset()
*
* This function is called from the Curl_multi_pollset() function. 'sock' is a
* pointer to an array to hold the file descriptors, with 'numsock' being the
* size of that array (in number of entries). This function is supposed to
* return bitmask indicating what file descriptors (referring to array indexes
* in the 'sock' array) to wait for, read/write.
*/
CURLcode Curl_async_pollset(struct Curl_easy *data,
struct Curl_resolv_async *async,
struct easy_pollset *ps);
#else /* CURLRES_ASYNCH */
/* convert these functions if an asynch resolver is not used */
#define Curl_async_global_init() CURLE_OK
#define Curl_async_global_cleanup() Curl_nop_stmt
#define Curl_async_get_ai(a,b,c,d) NULL
#define Curl_async_await(a,b,c) CURLE_COULDNT_RESOLVE_HOST
#define Curl_async_take_result(x, y, z) CURLE_COULDNT_RESOLVE_HOST
#define Curl_async_pollset(x, y, z) CURLE_OK
#endif /* !CURLRES_ASYNCH */
#if defined(CURLRES_ASYNCH) || !defined(CURL_DISABLE_DOH)
#define USE_CURL_ASYNC
#endif
#ifdef USE_CURL_ASYNC
struct Curl_resolv_async {
struct Curl_resolv_async *next;
#ifdef USE_RESOLV_ARES
struct async_ares_ctx ares;
#elif defined(USE_RESOLV_THREADED)
struct async_thrdd_ctx thrdd;
#endif
#ifndef CURL_DISABLE_DOH
struct doh_probes *doh; /* DoH specific data for this request */
#endif
struct curltime start;
timediff_t interval_end;
timediff_t timeout_ms;
CURLcode result;
uint32_t poll_interval;
uint32_t id; /* unique id per easy handle of the resolve operation */
/* what is being resolved */
uint16_t port;
uint8_t dns_queries; /* what queries are being performed */
uint8_t dns_responses; /* what queries had responses so far. */
uint8_t transport;
uint8_t queries_ongoing;
BIT(is_ipaddr);
BIT(is_ipv4addr);
BIT(done);
BIT(shutdown);
char hostname[1];
};
timediff_t Curl_async_timeleft_ms(struct Curl_easy *data,
struct Curl_resolv_async *async);
/* Shut down the given async resolve. */
void Curl_async_shutdown(struct Curl_easy *data,
struct Curl_resolv_async *async);
/* Frees the resources of the given async resolve and the struct itself. */
void Curl_async_destroy(struct Curl_easy *data,
struct Curl_resolv_async *async);
#else /* !USE_CURL_ASYNC */
#define Curl_async_shutdown(x,y) Curl_nop_stmt
#endif /* USE_CURL_ASYNC */
/********** end of generic resolver interface functions *****************/
#endif /* HEADER_CURL_ASYN_H */
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