curl/lib/psl.c

/***************************************************************************
 *                                  _   _ ____  _
 *  Project                     ___| | | |  _ \| |
 *                             / __| | | | |_) | |
 *                            | (__| |_| |  _ <| |___
 *                             \___|\___/|_| \_\_____|
 *
 * Copyright (C) 1998 - 2020, 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.
 *
 ***************************************************************************/

#include "curl_setup.h"

#include <curl/curl.h>

#ifdef USE_LIBPSL

#include "psl.h"
#include "share.h"

/* The last 3 #include files should be in this order */
#include "curl_printf.h"
#include "curl_memory.h"
#include "memdebug.h"

void Curl_psl_destroy(struct PslCache *pslcache)
{
  if(pslcache->psl) {
    if(pslcache->dynamic)
      psl_free((psl_ctx_t *) pslcache->psl);
    pslcache->psl = NULL;
    pslcache->dynamic = FALSE;
  }
}

static time_t now_seconds(void)
{
  struct curltime now = Curl_now();

  return now.tv_sec;
}

const psl_ctx_t *Curl_psl_use(struct Curl_easy *easy)
{
  struct PslCache *pslcache = easy->psl;
  const psl_ctx_t *psl;
  time_t now;

  if(!pslcache)
    return NULL;

  Curl_share_lock(easy, CURL_LOCK_DATA_PSL, CURL_LOCK_ACCESS_SHARED);
  now = now_seconds();
  if(!pslcache->psl || pslcache->expires <= now) {
    /* Let a chance to other threads to do the job: avoids deadlock. */
    Curl_share_unlock(easy, CURL_LOCK_DATA_PSL);

    /* Update cache: this needs an exclusive lock. */
    Curl_share_lock(easy, CURL_LOCK_DATA_PSL, CURL_LOCK_ACCESS_SINGLE);

    /* Recheck in case another thread did the job. */
    now = now_seconds();
    if(!pslcache->psl || pslcache->expires <= now) {
      bool dynamic = FALSE;
      time_t expires = TIME_T_MAX;

#if defined(PSL_VERSION_NUMBER) && PSL_VERSION_NUMBER >= 0x001000
      psl = psl_latest(NULL);
      dynamic = psl != NULL;
      /* Take care of possible time computation overflow. */
      expires = now < TIME_T_MAX - PSL_TTL? now + PSL_TTL: TIME_T_MAX;

      /* Only get the built-in PSL if we do not already have the "latest". */
      if(!psl && !pslcache->dynamic)
#endif

        psl = psl_builtin();

      if(psl) {
        Curl_psl_destroy(pslcache);
        pslcache->psl = psl;
        pslcache->dynamic = dynamic;
        pslcache->expires = expires;
      }
    }
    Curl_share_unlock(easy, CURL_LOCK_DATA_PSL);  /* Release exclusive lock. */
    Curl_share_lock(easy, CURL_LOCK_DATA_PSL, CURL_LOCK_ACCESS_SHARED);
  }
  psl = pslcache->psl;
  if(!psl)
    Curl_share_unlock(easy, CURL_LOCK_DATA_PSL);
  return psl;
}

void Curl_psl_release(struct Curl_easy *easy)
{
  Curl_share_unlock(easy, CURL_LOCK_DATA_PSL);
}

#endif /* USE_LIBPSL */