struct ssl_ctx_st
 
{
   SSL_METHOD *method;
 unsigned long options;
      unsigned long mode;
 
    STACK_OF(SSL_CIPHER) *cipher_list;
  /* same as above but sorted for lookup */
   STACK_OF(SSL_CIPHER) *cipher_list_by_id;
 
       struct x509_store_st /* X509_STORE */ *cert_store;
  struct lhash_st /* LHASH */ *sessions;  /* a set of SSL_SESSIONs */
 /* Most session-ids that will be cached, default is
  * SSL_SESSION_CACHE_MAX_SIZE_DEFAULT. 0 is unlimited. */
   unsigned long session_cache_size;
   struct ssl_session_st *session_cache_head;
  struct ssl_session_st *session_cache_tail;
 
     /* This can have one of 2 values, ored together,
     * SSL_SESS_CACHE_CLIENT,
    * SSL_SESS_CACHE_SERVER,
    * Default is SSL_SESSION_CACHE_SERVER, which means only
     * SSL_accept which cache SSL_SESSIONS. */
 
     int session_cache_mode;
 
 
 
      /* If timeout is not 0, it is the default timeout value set
  * when SSL_new() is called.  This has been put in to make
   * life easier to set things up */
 
     long session_timeout;
 
  /* If this callback is not null, it will be called each
      * time a session id is added to the cache.  If this function
        * returns 1, it means that the callback will do a
   * SSL_SESSION_free() when it has finished using it.  Otherwise,
     * on 0, it means the callback has finished with it.
         * If remove_session_cb is not null, it will be called when
  * a session-id is removed from the cache.  After the call,
  * OpenSSL will SSL_SESSION_free() it. */

 int (*new_session_cb)(struct ssl_st *ssl,SSL_SESSION *sess);
        void (*remove_session_cb)(struct ssl_ctx_st *ctx,SSL_SESSION *sess);
        SSL_SESSION *(*get_session_cb)(struct ssl_st *ssl,
          unsigned char *data,int len,int *copy);
     struct
      {
           int sess_connect;       /* SSL new conn - started */
                int sess_connect_renegotiate;/* SSL reneg - requested */
            int sess_connect_good;  /* SSL new conne/reneg - finished */
                int sess_accept;        /* SSL new accept - started */
              int sess_accept_renegotiate;/* SSL reneg - requested */
             int sess_accept_good;   /* SSL accept/reneg - finished */
           int sess_miss;          /* session lookup misses  */
                int sess_timeout;       /* reuse attempt on timeouted session */
            int sess_cache_full;    /* session removed due to full cache */
             int sess_hit;           /* session reuse actually done */
           int sess_cb_hit;        /* session-id that was not
 
                                      * in the cache was
                                  * passed back via the callback.  This
                                       * indicates that the application is
                                         * supplying session-id's from other
                                         * processes - spooky :-) */
 
   } stats;
 
       int references;
 
        void (*info_callback)();
 
       /* if defined, these override the X509_verify_cert() calls */
 
  int (*app_verify_callback)();
       char *app_verify_arg; /* never used; should be void * */
 
       /* default values to use in SSL structures */
 
  struct cert_st /* CERT */ *cert;
    int read_ahead;
     int verify_mode;
    int verify_depth;
   unsigned int sid_ctx_length;
        unsigned char sid_ctx[SSL_MAX_SID_CTX_LENGTH];
      int (*default_verify_callback)(int ok,X509_STORE_CTX *ctx);
 
    int purpose;            /* Purpose setting */
       int trust;              /* Trust setting */
 
    /* Default password callback. */
 
       pem_password_cb *default_passwd_callback;
 
      /* Default password callback user data. */
 
     void *default_passwd_callback_userdata;
 
        /* get client cert callback */
 
 int (*client_cert_cb)(/* SSL *ssl, X509 **x509, EVP_PKEY **pkey */);
 
   /* what we put in client cert requests */
 
      STACK_OF(X509_NAME) *client_CA;
 
        int quiet_shutdown;
 
    CRYPTO_EX_DATA ex_data;
 
        const EVP_MD *rsa_md5;  /* For SSLv2 - name is 'ssl2-md5' */
        const EVP_MD *md5;              /* For SSLv3/TLSv1 'ssl3-md5' */
    const EVP_MD *sha1;             /* For SSLv3/TLSv1 'ssl3->sha1' */
 
  STACK_OF(X509) *extra_certs;
STACK_OF(SSL_COMP) *comp_methods; /* stack of SSL_COMP, SSLv3/TLSv1 */
 
};