text: /*
   * Copyright 1995-2020 The OpenSSL Project Authors. All Rights Reserved.
   * Copyright 2005 Nokia. All rights reserved.
   *
   * Licensed under the OpenSSL license (the "License").  You may not use
   * this file except in compliance with the License.  You can obtain a copy
   * in the file LICENSE in the source distribution or at
   * https://www.openssl.org/source/license.html
   */
  
  #include <stdio.h>
  #include <openssl/rand.h>
  #include <openssl/engine.h>
  #include "internal/refcount.h"
  #include "internal/cryptlib.h"
  #include "ssl_local.h"
  #include "statem/statem_local.h"
  
  static void SSL_SESSION_list_remove(SSL_CTX *ctx, SSL_SESSION *s);
  static void SSL_SESSION_list_add(SSL_CTX *ctx, SSL_SESSION *s);
  static int remove_session_lock(SSL_CTX *ctx, SSL_SESSION *c, int lck);
  
  /*
   * SSL_get_session() and SSL_get1_session() are problematic in TLS1.3 because,
   * unlike in earlier protocol versions, the session ticket may not have been
   * sent yet even though a handshake has finished. The session ticket data could
   * come in sometime later...or even change if multiple session ticket messages
   * are sent from the server. The preferred way for applications to obtain
   * a resumable session is to use SSL_CTX_sess_set_new_cb().
   */
  
  SSL_SESSION *SSL_get_session(const SSL *ssl)
  /* aka SSL_get0_session; gets 0 objects, just returns a copy of the pointer */
  {
      return ssl->session;
  }
  
  SSL_SESSION *SSL_get1_session(SSL *ssl)
  /* variant of SSL_get_session: caller really gets something */
  {
      SSL_SESSION *sess;
      /*
       * Need to lock this all up rather than just use CRYPTO_add so that
       * somebody doesn't free ssl->session between when we check it's non-null
       * and when we up the reference count.
       */
      CRYPTO_THREAD_read_lock(ssl->lock);
      sess = ssl->session;
      if (sess)
          SSL_SESSION_up_ref(sess);
      CRYPTO_THREAD_unlock(ssl->lock);
      return sess;
  }
  
  int SSL_SESSION_set_ex_data(SSL_SESSION *s, int idx, void *arg)
  {
      return CRYPTO_set_ex_data(&s->ex_data, idx, arg);
  }
  
  void *SSL_SESSION_get_ex_data(const SSL_SESSION *s, int idx)
  {
      return CRYPTO_get_ex_data(&s->ex_data, idx);
  }
  
  SSL_SESSION *SSL_SESSION_new(void)
  {
      SSL_SESSION *ss;
  
      if (!OPENSSL_init_ssl(OPENSSL_INIT_LOAD_SSL_STRINGS, NULL))
          return NULL;
  
      ss = OPENSSL_zalloc(sizeof(*ss));
      if (ss == NULL) {
          SSLerr(SSL_F_SSL_SESSION_NEW, ERR_R_MALLOC_FAILURE);
          return NULL;
      }
  
      ss->verify_result = 1;      /* avoid 0 (= X509_V_OK) just in case */
      ss->references = 1;
      ss->timeout = 60 * 5 + 4;   /* 5 minute timeout by default */
      ss->time = (unsigned long)time(NULL);
      ss->lock = CRYPTO_THREAD_lock_new();
      if (ss->lock == NULL) {
          SSLerr(SSL_F_SSL_SESSION_NEW, ERR_R_MALLOC_FAILURE);
          OPENSSL_free(ss);
          return NULL;
      }
  
      if (!CRYPTO_new_ex_data(CRYPTO_EX_INDEX_SSL_SESSION, ss, &ss->ex_data)) {
          CRYPTO_THREAD_lock_free(ss->lock);
          OPENSSL_free(ss);
          return NULL;
      }
      return ss;
  }
  
  SSL_SESSION *SSL_SESSION_dup(SSL_SESSION *src)
  {
      return ssl_session_dup(src, 1);
  }
  
  /*
   * Create a new SSL_SESSION and duplicate the contents of |src| into it. If
   * ticket == 0 then no ticket information is duplicated, otherwise it is.
   */
  SSL_SESSION *ssl_session_dup(SSL_SESSION *src, int ticket)
  {
      SSL_SESSION *dest;
  
      dest = OPENSSL_malloc(sizeof(*dest));
      if (dest == NULL) {
          goto err;
      }
      memcpy(dest, src, sizeof(*dest));
  
      /*
       * Set the various pointers to NULL so that we can call SSL_SESSION_free in
       * the case of an error whilst halfway through constructing dest
       */
  #ifndef OPENSSL_NO_PSK
      dest->psk_identity_hint = NULL;
      dest->psk_identity = NULL;
  #endif
      dest->ext.hostname = NULL;
      dest->ext.tick = NULL;
      dest->ext.alpn_selected = NULL;
  #ifndef OPENSSL_NO_SRP
      dest->srp_username = NULL;
  #endif
      dest->peer_chain = NULL;
      dest->peer = NULL;
      dest->ticket_appdata = NULL;
      memset(&dest->ex_data, 0, sizeof(dest->ex_data));
  
      /* We deliberately don't copy the prev and next pointers */
      dest->prev = NULL;
      dest->next = NULL;
  
      dest->references = 1;
  
      dest->lock = CRYPTO_THREAD_lock_new();
      if (dest->lock == NULL)
          goto err;
  
      if (!CRYPTO_new_ex_data(CRYPTO_EX_INDEX_SSL_SESSION, dest, &dest->ex_data))
          goto err;
  
      if (src->peer != NULL) {
          if (!X509_up_ref(src->peer))
              goto err;
          dest->peer = src->peer;
      }
  
      if (src->peer_chain != NULL) {
          dest->peer_chain = X509_chain_up_ref(src->peer_chain);
          if (dest->peer_chain == NULL)
              goto err;
      }
  #ifndef OPENSSL_NO_PSK
      if (src->psk_identity_hint) {
          dest->psk_identity_hint = OPENSSL_strdup(src->psk_identity_hint);
          if (dest->psk_identity_hint == NULL) {
              goto err;
          }
      }
      if (src->psk_identity) {
          dest->psk_identity = OPENSSL_strdup(src->psk_identity);
          if (dest->psk_identity == NULL) {
              goto err;
          }
      }
  #endif
  
      if (!CRYPTO_dup_ex_data(CRYPTO_EX_INDEX_SSL_SESSION,
                              &dest->ex_data, &src->ex_data)) {
          goto err;
      }
  
      if (src->ext.hostname) {
          dest->ext.hostname = OPENSSL_strdup(src->ext.hostname);
          if (dest->ext.hostname == NULL) {
              goto err;
          }
      }
  
      if (ticket != 0 && src->ext.tick != NULL) {
          dest->ext.tick =
              OPENSSL_memdup(src->ext.tick, src->ext.ticklen);
          if (dest->ext.tick == NULL)
              goto err;
      } else {
          dest->ext.tick_lifetime_hint = 0;
          dest->ext.ticklen = 0;
      }
  
      if (src->ext.alpn_selected != NULL) {
          dest->ext.alpn_selected = OPENSSL_memdup(src->ext.alpn_selected,
                                                   src->ext.alpn_selected_len);
          if (dest->ext.alpn_selected == NULL)
              goto err;
      }
  
  #ifndef OPENSSL_NO_SRP
      if (src->srp_username) {
          dest->srp_username = OPENSSL_strdup(src->srp_username);
          if (dest->srp_username == NULL) {
              goto err;
          }
      }
  #endif
  
      if (src->ticket_appdata != NULL) {
          dest->ticket_appdata =
              OPENSSL_memdup(src->ticket_appdata, src->ticket_appdata_len);
          if (dest->ticket_appdata == NULL)
              goto err;
      }
  
      return dest;
   err:
      SSLerr(SSL_F_SSL_SESSION_DUP, ERR_R_MALLOC_FAILURE);
      SSL_SESSION_free(dest);
      return NULL;
  }
  
  const unsigned char *SSL_SESSION_get_id(const SSL_SESSION *s, unsigned int *len)
  {
      if (len)
          *len = (unsigned int)s->session_id_length;
      return s->session_id;
  }
  const unsigned char *SSL_SESSION_get0_id_context(const SSL_SESSION *s,
                                                  unsigned int *len)
  {
      if (len != NULL)
          *len = (unsigned int)s->sid_ctx_length;
      return s->sid_ctx;
  }
  
  unsigned int SSL_SESSION_get_compress_id(const SSL_SESSION *s)
  {
      return s->compress_meth;
  }
  
  /*
   * SSLv3/TLSv1 has 32 bytes (256 bits) of session ID space. As such, filling
   * the ID with random junk repeatedly until we have no conflict is going to
   * complete in one iteration pretty much "most" of the time (btw:
   * understatement). So, if it takes us 10 iterations and we still can't avoid
   * a conflict - well that's a reasonable point to call it quits. Either the
   * RAND code is broken or someone is trying to open roughly very close to
   * 2^256 SSL sessions to our server. How you might store that many sessions
   * is perhaps a more interesting question ...
   */
  
  #define MAX_SESS_ID_ATTEMPTS 10
  static int def_generate_session_id(SSL *ssl, unsigned char *id,
                                     unsigned int *id_len)
  {
      unsigned int retry = 0;
      do
          if (RAND_bytes(id, *id_len) <= 0)
              return 0;
      while (SSL_has_matching_session_id(ssl, id, *id_len) &&
             (++retry < MAX_SESS_ID_ATTEMPTS)) ;
      if (retry < MAX_SESS_ID_ATTEMPTS)
          return 1;
      /* else - woops a session_id match */
      /*
       * XXX We should also check the external cache -- but the probability of
       * a collision is negligible, and we could not prevent the concurrent
       * creation of sessions with identical IDs since we currently don't have
       * means to atomically check whether a session ID already exists and make
       * a reservation for it if it does not (this problem applies to the
       * internal cache as well).
       */
      return 0;
  }
  
  int ssl_generate_session_id(SSL *s, SSL_SESSION *ss)
  {
      unsigned int tmp;
      GEN_SESSION_CB cb = def_generate_session_id;
  
      switch (s->version) {
      case SSL3_VERSION:
      case TLS1_VERSION:
      case TLS1_1_VERSION:
      case TLS1_2_VERSION:
      case TLS1_3_VERSION:
      case DTLS1_BAD_VER:
      case DTLS1_VERSION:
      case DTLS1_2_VERSION:
          ss->session_id_length = SSL3_SSL_SESSION_ID_LENGTH;
          break;
      default:
          SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_SSL_GENERATE_SESSION_ID,
                   SSL_R_UNSUPPORTED_SSL_VERSION);
          return 0;
      }
  
      /*-
       * If RFC5077 ticket, use empty session ID (as server).
       * Note that:
       * (a) ssl_get_prev_session() does lookahead into the
       *     ClientHello extensions to find the session ticket.
       *     When ssl_get_prev_session() fails, statem_srvr.c calls
       *     ssl_get_new_session() in tls_process_client_hello().
       *     At that point, it has not yet parsed the extensions,
       *     however, because of the lookahead, it already knows
       *     whether a ticket is expected or not.
       *
       * (b) statem_clnt.c calls ssl_get_new_session() before parsing
       *     ServerHello extensions, and before recording the session
       *     ID received from the server, so this block is a noop.
       */
      if (s->ext.ticket_expected) {
          ss->session_id_length = 0;
          return 1;
      }
  
      /* Choose which callback will set the session ID */
      CRYPTO_THREAD_read_lock(s->lock);
      CRYPTO_THREAD_read_lock(s->session_ctx->lock);
      if (s->generate_session_id)
          cb = s->generate_session_id;
      else if (s->session_ctx->generate_session_id)
          cb = s->session_ctx->generate_session_id;
      CRYPTO_THREAD_unlock(s->session_ctx->lock);
      CRYPTO_THREAD_unlock(s->lock);
      /* Choose a session ID */
      memset(ss->session_id, 0, ss->session_id_length);
      tmp = (int)ss->session_id_length;
      if (!cb(s, ss->session_id, &tmp)) {
          /* The callback failed */
          SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_SSL_GENERATE_SESSION_ID,
                   SSL_R_SSL_SESSION_ID_CALLBACK_FAILED);
          return 0;
      }
      /*
       * Don't allow the callback to set the session length to zero. nor
       * set it higher than it was.
       */
      if (tmp == 0 || tmp > ss->session_id_length) {
          /* The callback set an illegal length */
          SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_SSL_GENERATE_SESSION_ID,
                   SSL_R_SSL_SESSION_ID_HAS_BAD_LENGTH);
          return 0;
      }
      ss->session_id_length = tmp;
      /* Finally, check for a conflict */
      if (SSL_has_matching_session_id(s, ss->session_id,
                                      (unsigned int)ss->session_id_length)) {
          SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_SSL_GENERATE_SESSION_ID,
                   SSL_R_SSL_SESSION_ID_CONFLICT);
          return 0;
      }
  
      return 1;
  }
  
  int ssl_get_new_session(SSL *s, int session)
  {
      /* This gets used by clients and servers. */
  
      SSL_SESSION *ss = NULL;
  
      if ((ss = SSL_SESSION_new()) == NULL) {
          SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_SSL_GET_NEW_SESSION,
                   ERR_R_MALLOC_FAILURE);
          return 0;
      }
  
      /* If the context has a default timeout, use it */
      if (s->session_ctx->session_timeout == 0)
          ss->timeout = SSL_get_default_timeout(s);
      else
          ss->timeout = s->session_ctx->session_timeout;
  
      SSL_SESSION_free(s->session);
      s->session = NULL;
  
      if (session) {
          if (SSL_IS_TLS13(s)) {
              /*
               * We generate the session id while constructing the
               * NewSessionTicket in TLSv1.3.
               */
              ss->session_id_length = 0;
          } else if (!ssl_generate_session_id(s, ss)) {
              /* SSLfatal() already called */
              SSL_SESSION_free(ss);
              return 0;
          }
  
      } else {
          ss->session_id_length = 0;
      }
  
      if (s->sid_ctx_length > sizeof(ss->sid_ctx)) {
          SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_SSL_GET_NEW_SESSION,
                   ERR_R_INTERNAL_ERROR);
          SSL_SESSION_free(ss);
          return 0;
      }
      memcpy(ss->sid_ctx, s->sid_ctx, s->sid_ctx_length);
      ss->sid_ctx_length = s->sid_ctx_length;
      s->session = ss;
      ss->ssl_version = s->version;
      ss->verify_result = X509_V_OK;
  
      /* If client supports extended master secret set it in session */
      if (s->s3->flags & TLS1_FLAGS_RECEIVED_EXTMS)
          ss->flags |= SSL_SESS_FLAG_EXTMS;
  
      return 1;
  }
  
  SSL_SESSION *lookup_sess_in_cache(SSL *s, const unsigned char *sess_id,
                                    size_t sess_id_len)
  {
      SSL_SESSION *ret = NULL;
  
      if ((s->session_ctx->session_cache_mode
           & SSL_SESS_CACHE_NO_INTERNAL_LOOKUP) == 0) {
          SSL_SESSION data;
  
          data.ssl_version = s->version;
          if (!ossl_assert(sess_id_len <= SSL_MAX_SSL_SESSION_ID_LENGTH))
              return NULL;
  
          memcpy(data.session_id, sess_id, sess_id_len);
          data.session_id_length = sess_id_len;
  
          CRYPTO_THREAD_read_lock(s->session_ctx->lock);
          ret = lh_SSL_SESSION_retrieve(s->session_ctx->sessions, &data);
          if (ret != NULL) {
              /* don't allow other threads to steal it: */
              SSL_SESSION_up_ref(ret);
          }
          CRYPTO_THREAD_unlock(s->session_ctx->lock);
          if (ret == NULL)
              tsan_counter(&s->session_ctx->stats.sess_miss);
      }
  
      if (ret == NULL && s->session_ctx->get_session_cb != NULL) {
          int copy = 1;
  
          ret = s->session_ctx->get_session_cb(s, sess_id, sess_id_len, &copy);
  
          if (ret != NULL) {
              tsan_counter(&s->session_ctx->stats.sess_cb_hit);
  
              /*
               * Increment reference count now if the session callback asks us
               * to do so (note that if the session structures returned by the
               * callback are shared between threads, it must handle the
               * reference count itself [i.e. copy == 0], or things won't be
               * thread-safe).
               */
              if (copy)
                  SSL_SESSION_up_ref(ret);
  
              /*
               * Add the externally cached session to the internal cache as
               * well if and only if we are supposed to.
               */
              if ((s->session_ctx->session_cache_mode &
                   SSL_SESS_CACHE_NO_INTERNAL_STORE) == 0) {
                  /*
                   * Either return value of SSL_CTX_add_session should not
                   * interrupt the session resumption process. The return
                   * value is intentionally ignored.
                   */
                  (void)SSL_CTX_add_session(s->session_ctx, ret);
              }
          }
      }
  
      return ret;
  }
  
  /*-
   * ssl_get_prev attempts to find an SSL_SESSION to be used to resume this
   * connection. It is only called by servers.
   *
   *   hello: The parsed ClientHello data
   *
   * Returns:
   *   -1: fatal error
   *    0: no session found
   *    1: a session may have been found.
   *
   * Side effects:
   *   - If a session is found then s->session is pointed at it (after freeing an
   *     existing session if need be) and s->verify_result is set from the session.
   *   - Both for new and resumed sessions, s->ext.ticket_expected is set to 1
   *     if the server should issue a new session ticket (to 0 otherwise).
   */
  int ssl_get_prev_session(SSL *s, CLIENTHELLO_MSG *hello)
  {
      /* This is used only by servers. */
  
      SSL_SESSION *ret = NULL;
      int fatal = 0;
      int try_session_cache = 0;
      SSL_TICKET_STATUS r;
  
      if (SSL_IS_TLS13(s)) {
          /*
           * By default we will send a new ticket. This can be overridden in the
           * ticket processing.
           */
          s->ext.ticket_expected = 1;
          if (!tls_parse_extension(s, TLSEXT_IDX_psk_kex_modes,
                                   SSL_EXT_CLIENT_HELLO, hello->pre_proc_exts,
                                   NULL, 0)
                  || !tls_parse_extension(s, TLSEXT_IDX_psk, SSL_EXT_CLIENT_HELLO,
                                          hello->pre_proc_exts, NULL, 0))
              return -1;
  
          ret = s->session;
      } else {
          /* sets s->ext.ticket_expected */
          r = tls_get_ticket_from_client(s, hello, &ret);
          switch (r) {
          case SSL_TICKET_FATAL_ERR_MALLOC:
          case SSL_TICKET_FATAL_ERR_OTHER:
              fatal = 1;
              SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_SSL_GET_PREV_SESSION,
                       ERR_R_INTERNAL_ERROR);
              goto err;
          case SSL_TICKET_NONE:
          case SSL_TICKET_EMPTY:
              if (hello->session_id_len > 0) {
                  try_session_cache = 1;
                  ret = lookup_sess_in_cache(s, hello->session_id,
                                             hello->session_id_len);
              }
              break;
          case SSL_TICKET_NO_DECRYPT:
          case SSL_TICKET_SUCCESS:
          case SSL_TICKET_SUCCESS_RENEW:
              break;
          }
      }
  
      if (ret == NULL)
          goto err;
  
      /* Now ret is non-NULL and we own one of its reference counts. */
  
      /* Check TLS version consistency */
      if (ret->ssl_version != s->version)
          goto err;
  
      if (ret->sid_ctx_length != s->sid_ctx_length
          || memcmp(ret->sid_ctx, s->sid_ctx, ret->sid_ctx_length)) {
          /*
           * We have the session requested by the client, but we don't want to
           * use it in this context.
           */
          goto err;               /* treat like cache miss */
      }
  
      if ((s->verify_mode & SSL_VERIFY_PEER) && s->sid_ctx_length == 0) {
          /*
           * We can't be sure if this session is being used out of context,
           * which is especially important for SSL_VERIFY_PEER. The application
           * should have used SSL[_CTX]_set_session_id_context. For this error
           * case, we generate an error instead of treating the event like a
           * cache miss (otherwise it would be easy for applications to
           * effectively disable the session cache by accident without anyone
           * noticing).
           */
  
          SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_SSL_GET_PREV_SESSION,
                   SSL_R_SESSION_ID_CONTEXT_UNINITIALIZED);
          fatal = 1;
          goto err;
      }
  
      if (ret->timeout < (long)(time(NULL) - ret->time)) { /* timeout */
          tsan_counter(&s->session_ctx->stats.sess_timeout);
          if (try_session_cache) {
              /* session was from the cache, so remove it */
              SSL_CTX_remove_session(s->session_ctx, ret);
          }
          goto err;
      }
  
      /* Check extended master secret extension consistency */
      if (ret->flags & SSL_SESS_FLAG_EXTMS) {
          /* If old session includes extms, but new does not: abort handshake */
          if (!(s->s3->flags & TLS1_FLAGS_RECEIVED_EXTMS)) {
              SSLfatal(s, SSL_AD_ILLEGAL_PARAMETER, SSL_F_SSL_GET_PREV_SESSION,
                       SSL_R_INCONSISTENT_EXTMS);
              fatal = 1;
              goto err;
          }
      } else if (s->s3->flags & TLS1_FLAGS_RECEIVED_EXTMS) {
          /* If new session includes extms, but old does not: do not resume */
          goto err;
      }
  
      if (!SSL_IS_TLS13(s)) {
          /* We already did this for TLS1.3 */
          SSL_SESSION_free(s->session);
          s->session = ret;
      }
  
      tsan_counter(&s->session_ctx->stats.sess_hit);
      s->verify_result = s->session->verify_result;
      return 1;
  
   err:
      if (ret != NULL) {
          SSL_SESSION_free(ret);
          /* In TLSv1.3 s->session was already set to ret, so we NULL it out */
          if (SSL_IS_TLS13(s))
              s->session = NULL;
  
          if (!try_session_cache) {
              /*
               * The session was from a ticket, so we should issue a ticket for
               * the new session
               */
              s->ext.ticket_expected = 1;
          }
      }
      if (fatal)
          return -1;
  
      return 0;
  }
  
  int SSL_CTX_add_session(SSL_CTX *ctx, SSL_SESSION *c)
  {
      int ret = 0;
      SSL_SESSION *s;
  
      /*
       * add just 1 reference count for the SSL_CTX's session cache even though
       * it has two ways of access: each session is in a doubly linked list and
       * an lhash
       */
      SSL_SESSION_up_ref(c);
      /*
       * if session c is in already in cache, we take back the increment later
       */
  
      CRYPTO_THREAD_write_lock(ctx->lock);
      s = lh_SSL_SESSION_insert(ctx->sessions, c);
  
      /*
       * s != NULL iff we already had a session with the given PID. In this
       * case, s == c should hold (then we did not really modify
       * ctx->sessions), or we're in trouble.
       */
      if (s != NULL && s != c) {
          /* We *are* in trouble ... */
          SSL_SESSION_list_remove(ctx, s);
          SSL_SESSION_free(s);
          /*
           * ... so pretend the other session did not exist in cache (we cannot
           * handle two SSL_SESSION structures with identical session ID in the
           * same cache, which could happen e.g. when two threads concurrently
           * obtain the same session from an external cache)
           */
          s = NULL;
      } else if (s == NULL &&
                 lh_SSL_SESSION_retrieve(ctx->sessions, c) == NULL) {
          /* s == NULL can also mean OOM error in lh_SSL_SESSION_insert ... */
  
          /*
           * ... so take back the extra reference and also don't add
           * the session to the SSL_SESSION_list at this time
           */
          s = c;
      }
  
      /* Put at the head of the queue unless it is already in the cache */
      if (s == NULL)
          SSL_SESSION_list_add(ctx, c);
  
      if (s != NULL) {
          /*
           * existing cache entry -- decrement previously incremented reference
           * count because it already takes into account the cache
           */
  
          SSL_SESSION_free(s);    /* s == c */
          ret = 0;
      } else {
          /*
           * new cache entry -- remove old ones if cache has become too large
           */
  
          ret = 1;
  
          if (SSL_CTX_sess_get_cache_size(ctx) > 0) {
              while (SSL_CTX_sess_number(ctx) > SSL_CTX_sess_get_cache_size(ctx)) {
                  if (!remove_session_lock(ctx, ctx->session_cache_tail, 0))
                      break;
                  else
                      tsan_counter(&ctx->stats.sess_cache_full);
              }
          }
      }
      CRYPTO_THREAD_unlock(ctx->lock);
      return ret;
  }
  
  int SSL_CTX_remove_session(SSL_CTX *ctx, SSL_SESSION *c)
  {
      return remove_session_lock(ctx, c, 1);
  }
  
  static int remove_session_lock(SSL_CTX *ctx, SSL_SESSION *c, int lck)
  {
      SSL_SESSION *r;
      int ret = 0;
  
      if ((c != NULL) && (c->session_id_length != 0)) {
          if (lck)
              CRYPTO_THREAD_write_lock(ctx->lock);
          if ((r = lh_SSL_SESSION_retrieve(ctx->sessions, c)) != NULL) {
              ret = 1;
              r = lh_SSL_SESSION_delete(ctx->sessions, r);
              SSL_SESSION_list_remove(ctx, r);
          }
          c->not_resumable = 1;
  
          if (lck)
              CRYPTO_THREAD_unlock(ctx->lock);
  
          if (ctx->remove_session_cb != NULL)
              ctx->remove_session_cb(ctx, c);
  
          if (ret)
              SSL_SESSION_free(r);
      } else
          ret = 0;
      return ret;
  }
  
  void SSL_SESSION_free(SSL_SESSION *ss)
  {
      int i;
  
      if (ss == NULL)
          return;
      CRYPTO_DOWN_REF(&ss->references, &i, ss->lock);
      REF_PRINT_COUNT("SSL_SESSION", ss);
      if (i > 0)
          return;
      REF_ASSERT_ISNT(i < 0);
  
      CRYPTO_free_ex_data(CRYPTO_EX_INDEX_SSL_SESSION, ss, &ss->ex_data);
  
      OPENSSL_cleanse(ss->master_key, sizeof(ss->master_key));
      OPENSSL_cleanse(ss->session_id, sizeof(ss->session_id));
      X509_free(ss->peer);
      sk_X509_pop_free(ss->peer_chain, X509_free);
      OPENSSL_free(ss->ext.hostname);
      OPENSSL_free(ss->ext.tick);
  #ifndef OPENSSL_NO_PSK
      OPENSSL_free(ss->psk_identity_hint);
      OPENSSL_free(ss->psk_identity);
  #endif
  #ifndef OPENSSL_NO_SRP
      OPENSSL_free(ss->srp_username);
  #endif
      OPENSSL_free(ss->ext.alpn_selected);
      OPENSSL_free(ss->ticket_appdata);
      CRYPTO_THREAD_lock_free(ss->lock);
      OPENSSL_clear_free(ss, sizeof(*ss));
  }
  
  int SSL_SESSION_up_ref(SSL_SESSION *ss)
  {
      int i;
  
      if (CRYPTO_UP_REF(&ss->references, &i, ss->lock) <= 0)
          return 0;
  
      REF_PRINT_COUNT("SSL_SESSION", ss);
      REF_ASSERT_ISNT(i < 2);
      return ((i > 1) ? 1 : 0);
  }
  
  int SSL_set_session(SSL *s, SSL_SESSION *session)
  {
      ssl_clear_bad_session(s);
      if (s->ctx->method != s->method) {
          if (!SSL_set_ssl_method(s, s->ctx->method))
              return 0;
      }
  
      if (session != NULL) {
          SSL_SESSION_up_ref(session);
          s->verify_result = session->verify_result;
      }
      SSL_SESSION_free(s->session);
      s->session = session;
  
      return 1;
  }
  
  int SSL_SESSION_set1_id(SSL_SESSION *s, const unsigned char *sid,
                          unsigned int sid_len)
  {
      if (sid_len > SSL_MAX_SSL_SESSION_ID_LENGTH) {
        SSLerr(SSL_F_SSL_SESSION_SET1_ID,
               SSL_R_SSL_SESSION_ID_TOO_LONG);
        return 0;
      }
      s->session_id_length = sid_len;
      if (sid != s->session_id)
          memcpy(s->session_id, sid, sid_len);
      return 1;
  }
  
  long SSL_SESSION_set_timeout(SSL_SESSION *s, long t)
  {
      if (s == NULL)
          return 0;
      s->timeout = t;
      return 1;
  }
  
  long SSL_SESSION_get_timeout(const SSL_SESSION *s)
  {
      if (s == NULL)
          return 0;
      return s->timeout;
  }
  
  long SSL_SESSION_get_time(const SSL_SESSION *s)
  {
      if (s == NULL)
          return 0;
      return s->time;
  }
  
  long SSL_SESSION_set_time(SSL_SESSION *s, long t)
  {
      if (s == NULL)
          return 0;
      s->time = t;
      return t;
  }
  
  int SSL_SESSION_get_protocol_version(const SSL_SESSION *s)
  {
      return s->ssl_version;
  }
  
  int SSL_SESSION_set_protocol_version(SSL_SESSION *s, int version)
  {
      s->ssl_version = version;
      return 1;
  }
  
  const SSL_CIPHER *SSL_SESSION_get0_cipher(const SSL_SESSION *s)
  {
      return s->cipher;
  }
  
  int SSL_SESSION_set_cipher(SSL_SESSION *s, const SSL_CIPHER *cipher)
  {
      s->cipher = cipher;
      return 1;
  }
  
  const char *SSL_SESSION_get0_hostname(const SSL_SESSION *s)
  {
      return s->ext.hostname;
  }
  
  int SSL_SESSION_set1_hostname(SSL_SESSION *s, const char *hostname)
  {
      OPENSSL_free(s->ext.hostname);
      if (hostname == NULL) {
          s->ext.hostname = NULL;
          return 1;
      }
      s->ext.hostname = OPENSSL_strdup(hostname);
  
      return s->ext.hostname != NULL;
  }
  
  int SSL_SESSION_has_ticket(const SSL_SESSION *s)
  {
      return (s->ext.ticklen > 0) ? 1 : 0;
  }
  
  unsigned long SSL_SESSION_get_ticket_lifetime_hint(const SSL_SESSION *s)
  {
      return s->ext.tick_lifetime_hint;
  }
  
  void SSL_SESSION_get0_ticket(const SSL_SESSION *s, const unsigned char **tick,
                               size_t *len)
  {
      *len = s->ext.ticklen;
      if (tick != NULL)
          *tick = s->ext.tick;
  }
  
  uint32_t SSL_SESSION_get_max_early_data(const SSL_SESSION *s)
  {
      return s->ext.max_early_data;
  }
  
  int SSL_SESSION_set_max_early_data(SSL_SESSION *s, uint32_t max_early_data)
  {
      s->ext.max_early_data = max_early_data;
  
      return 1;
  }
  
  void SSL_SESSION_get0_alpn_selected(const SSL_SESSION *s,
                                      const unsigned char **alpn,
                                      size_t *len)
  {
      *alpn = s->ext.alpn_selected;
      *len = s->ext.alpn_selected_len;
  }
  
  int SSL_SESSION_set1_alpn_selected(SSL_SESSION *s, const unsigned char *alpn,
                                     size_t len)
  {
      OPENSSL_free(s->ext.alpn_selected);
      if (alpn == NULL || len == 0) {
          s->ext.alpn_selected = NULL;
          s->ext.alpn_selected_len = 0;
          return 1;
      }
      s->ext.alpn_selected = OPENSSL_memdup(alpn, len);
      if (s->ext.alpn_selected == NULL) {
          s->ext.alpn_selected_len = 0;
          return 0;
      }
      s->ext.alpn_selected_len = len;
  
      return 1;
  }
  
  X509 *SSL_SESSION_get0_peer(SSL_SESSION *s)
  {
      return s->peer;
  }
  
  int SSL_SESSION_set1_id_context(SSL_SESSION *s, const unsigned char *sid_ctx,
                                  unsigned int sid_ctx_len)
  {
      if (sid_ctx_len > SSL_MAX_SID_CTX_LENGTH) {
          SSLerr(SSL_F_SSL_SESSION_SET1_ID_CONTEXT,
                 SSL_R_SSL_SESSION_ID_CONTEXT_TOO_LONG);
          return 0;
      }
      s->sid_ctx_length = sid_ctx_len;
      if (sid_ctx != s->sid_ctx)
          memcpy(s->sid_ctx, sid_ctx, sid_ctx_len);
  
      return 1;
  }
  
  int SSL_SESSION_is_resumable(const SSL_SESSION *s)
  {
      /*
       * In the case of EAP-FAST, we can have a pre-shared "ticket" without a
       * session ID.
       */
      return !s->not_resumable
             && (s->session_id_length > 0 || s->ext.ticklen > 0);
  }
  
  long SSL_CTX_set_timeout(SSL_CTX *s, long t)
  {
      long l;
      if (s == NULL)
          return 0;
      l = s->session_timeout;
      s->session_timeout = t;
      return l;
  }
  
  long SSL_CTX_get_timeout(const SSL_CTX *s)
  {
      if (s == NULL)
          return 0;
      return s->session_timeout;
  }
  
  int SSL_set_session_secret_cb(SSL *s,
                                tls_session_secret_cb_fn tls_session_secret_cb,
                                void *arg)
  {
      if (s == NULL)
          return 0;
      s->ext.session_secret_cb = tls_session_secret_cb;
      s->ext.session_secret_cb_arg = arg;
      return 1;
  }
  
  int SSL_set_session_ticket_ext_cb(SSL *s, tls_session_ticket_ext_cb_fn cb,
                                    void *arg)
  {
      if (s == NULL)
          return 0;
      s->ext.session_ticket_cb = cb;
      s->ext.session_ticket_cb_arg = arg;
      return 1;
  }
  
  int SSL_set_session_ticket_ext(SSL *s, void *ext_data, int ext_len)
  {
      if (s->version >= TLS1_VERSION) {
          OPENSSL_free(s->ext.session_ticket);
          s->ext.session_ticket = NULL;
          s->ext.session_ticket =
              OPENSSL_malloc(sizeof(TLS_SESSION_TICKET_EXT) + ext_len);
          if (s->ext.session_ticket == NULL) {
              SSLerr(SSL_F_SSL_SET_SESSION_TICKET_EXT, ERR_R_MALLOC_FAILURE);
              return 0;
          }
  
          if (ext_data != NULL) {
              s->ext.session_ticket->length = ext_len;
              s->ext.session_ticket->data = s->ext.session_ticket + 1;
              memcpy(s->ext.session_ticket->data, ext_data, ext_len);
          } else {
              s->ext.session_ticket->length = 0;
              s->ext.session_ticket->data = NULL;
          }
  
          return 1;
      }
  
      return 0;
  }
  
  typedef struct timeout_param_st {
      SSL_CTX *ctx;
      long time;
      LHASH_OF(SSL_SESSION) *cache;
  } TIMEOUT_PARAM;
  
  static void timeout_cb(SSL_SESSION *s, TIMEOUT_PARAM *p)
  {
      if ((p->time == 0) || (p->time > (s->time + s->timeout))) { /* timeout */
          /*
           * The reason we don't call SSL_CTX_remove_session() is to save on
           * locking overhead
           */
          (void)lh_SSL_SESSION_delete(p->cache, s);
          SSL_SESSION_list_remove(p->ctx, s);
          s->not_resumable = 1;
          if (p->ctx->remove_session_cb != NULL)
              p->ctx->remove_session_cb(p->ctx, s);
          SSL_SESSION_free(s);
      }
  }
  
  IMPLEMENT_LHASH_DOALL_ARG(SSL_SESSION, TIMEOUT_PARAM);
  
  void SSL_CTX_flush_sessions(SSL_CTX *s, long t)
  {
      unsigned long i;
      TIMEOUT_PARAM tp;
  
      tp.ctx = s;
      tp.cache = s->sessions;
      if (tp.cache == NULL)
          return;
      tp.time = t;
      CRYPTO_THREAD_write_lock(s->lock);
      i = lh_SSL_SESSION_get_down_load(s->sessions);
      lh_SSL_SESSION_set_down_load(s->sessions, 0);
      lh_SSL_SESSION_doall_TIMEOUT_PARAM(tp.cache, timeout_cb, &tp);
      lh_SSL_SESSION_set_down_load(s->sessions, i);
      CRYPTO_THREAD_unlock(s->lock);
  }
  
  int ssl_clear_bad_session(SSL *s)
  {
      if ((s->session != NULL) &&
          !(s->shutdown & SSL_SENT_SHUTDOWN) &&
          !(SSL_in_init(s) || SSL_in_before(s))) {
          SSL_CTX_remove_session(s->session_ctx, s->session);
          return 1;
      } else
          return 0;
  }
  
  /* locked by SSL_CTX in the calling function */
  static void SSL_SESSION_list_remove(SSL_CTX *ctx, SSL_SESSION *s)
  {
      if ((s->next == NULL) || (s->prev == NULL))
          return;
  
      if (s->next == (SSL_SESSION *)&(ctx->session_cache_tail)) {
          /* last element in list */
          if (s->prev == (SSL_SESSION *)&(ctx->session_cache_head)) {
              /* only one element in list */
              ctx->session_cache_head = NULL;
              ctx->session_cache_tail = NULL;
          } else {
              ctx->session_cache_tail = s->prev;
              s->prev->next = (SSL_SESSION *)&(ctx->session_cache_tail);
          }
      } else {
          if (s->prev == (SSL_SESSION *)&(ctx->session_cache_head)) {
              /* first element in list */
              ctx->session_cache_head = s->next;
              s->next->prev = (SSL_SESSION *)&(ctx->session_cache_head);
          } else {
              /* middle of list */
              s->next->prev = s->prev;
              s->prev->next = s->next;
          }
      }
      s->prev = s->next = NULL;
  }
  
  static void SSL_SESSION_list_add(SSL_CTX *ctx, SSL_SESSION *s)
  {
      if ((s->next != NULL) && (s->prev != NULL))
          SSL_SESSION_list_remove(ctx, s);
  
      if (ctx->session_cache_head == NULL) {
          ctx->session_cache_head = s;
          ctx->session_cache_tail = s;
          s->prev = (SSL_SESSION *)&(ctx->session_cache_head);
          s->next = (SSL_SESSION *)&(ctx->session_cache_tail);
      } else {
          s->next = ctx->session_cache_head;
          s->next->prev = s;
          s->prev = (SSL_SESSION *)&(ctx->session_cache_head);
          ctx->session_cache_head = s;
      }
  }
  
  void SSL_CTX_sess_set_new_cb(SSL_CTX *ctx,
                               int (*cb) (struct ssl_st *ssl, SSL_SESSION *sess))
  {
      ctx->new_session_cb = cb;
  }
  
  int (*SSL_CTX_sess_get_new_cb(SSL_CTX *ctx)) (SSL *ssl, SSL_SESSION *sess) {
      return ctx->new_session_cb;
  }
  
  void SSL_CTX_sess_set_remove_cb(SSL_CTX *ctx,
                                  void (*cb) (SSL_CTX *ctx, SSL_SESSION *sess))
  {
      ctx->remove_session_cb = cb;
  }
  
  void (*SSL_CTX_sess_get_remove_cb(SSL_CTX *ctx)) (SSL_CTX *ctx,
                                                    SSL_SESSION *sess) {
      return ctx->remove_session_cb;
  }
  
  void SSL_CTX_sess_set_get_cb(SSL_CTX *ctx,
                               SSL_SESSION *(*cb) (struct ssl_st *ssl,
                                                   const unsigned char *data,
                                                   int len, int *copy))
  {
      ctx->get_session_cb = cb;
  }
  
  SSL_SESSION *(*SSL_CTX_sess_get_get_cb(SSL_CTX *ctx)) (SSL *ssl,
                                                         const unsigned char
                                                         *data, int len,
                                                         int *copy) {
      return ctx->get_session_cb;
  }
  
  void SSL_CTX_set_info_callback(SSL_CTX *ctx,
                                 void (*cb) (const SSL *ssl, int type, int val))
  {
      ctx->info_callback = cb;
  }
  
  void (*SSL_CTX_get_info_callback(SSL_CTX *ctx)) (const SSL *ssl, int type,
                                                   int val) {
      return ctx->info_callback;
  }
  
  void SSL_CTX_set_client_cert_cb(SSL_CTX *ctx,
                                  int (*cb) (SSL *ssl, X509 **x509,
                                             EVP_PKEY **pkey))
  {
      ctx->client_cert_cb = cb;
  }
  
  int (*SSL_CTX_get_client_cert_cb(SSL_CTX *ctx)) (SSL *ssl, X509 **x509,
                                                   EVP_PKEY **pkey) {
      return ctx->client_cert_cb;
  }
  
  #ifndef OPENSSL_NO_ENGINE
  int SSL_CTX_set_client_cert_engine(SSL_CTX *ctx, ENGINE *e)
  {
      if (!ENGINE_init(e)) {
          SSLerr(SSL_F_SSL_CTX_SET_CLIENT_CERT_ENGINE, ERR_R_ENGINE_LIB);
          return 0;
      }
      if (!ENGINE_get_ssl_client_cert_function(e)) {
          SSLerr(SSL_F_SSL_CTX_SET_CLIENT_CERT_ENGINE,
                 SSL_R_NO_CLIENT_CERT_METHOD);
          ENGINE_finish(e);
          return 0;
      }
      ctx->client_cert_engine = e;
      return 1;
  }
  #endif
  
  void SSL_CTX_set_cookie_generate_cb(SSL_CTX *ctx,
                                      int (*cb) (SSL *ssl,
                                                 unsigned char *cookie,
                                                 unsigned int *cookie_len))
  {
      ctx->app_gen_cookie_cb = cb;
  }
  
  void SSL_CTX_set_cookie_verify_cb(SSL_CTX *ctx,
                                    int (*cb) (SSL *ssl,
                                               const unsigned char *cookie,
                                               unsigned int cookie_len))
  {
      ctx->app_verify_cookie_cb = cb;
  }
  
  int SSL_SESSION_set1_ticket_appdata(SSL_SESSION *ss, const void *data, size_t len)
  {
      OPENSSL_free(ss->ticket_appdata);
      ss->ticket_appdata_len = 0;
      if (data == NULL || len == 0) {
          ss->ticket_appdata = NULL;
          return 1;
      }
      ss->ticket_appdata = OPENSSL_memdup(data, len);
      if (ss->ticket_appdata != NULL) {
          ss->ticket_appdata_len = len;
          return 1;
      }
      return 0;
  }
  
  int SSL_SESSION_get0_ticket_appdata(SSL_SESSION *ss, void **data, size_t *len)
  {
      *data = ss->ticket_appdata;
      *len = ss->ticket_appdata_len;
      return 1;
  }
  
  void SSL_CTX_set_stateless_cookie_generate_cb(
      SSL_CTX *ctx,
      int (*cb) (SSL *ssl,
                 unsigned char *cookie,
                 size_t *cookie_len))
  {
      ctx->gen_stateless_cookie_cb = cb;
  }
  
  void SSL_CTX_set_stateless_cookie_verify_cb(
      SSL_CTX *ctx,
      int (*cb) (SSL *ssl,
                 const unsigned char *cookie,
                 size_t cookie_len))
  {
      ctx->verify_stateless_cookie_cb = cb;
  }
  
  IMPLEMENT_PEM_rw(SSL_SESSION, SSL_SESSION, PEM_STRING_SSL_SESSION, SSL_SESSION)
  