text: /* crypto/engine/eng_dyn.c */
  /*
   * Written by Geoff Thorpe (geoff@geoffthorpe.net) for the OpenSSL project
   * 2001.
   */
  /* ====================================================================
   * Copyright (c) 1999-2001 The OpenSSL Project.  All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   *
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   *
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in
   *    the documentation and/or other materials provided with the
   *    distribution.
   *
   * 3. All advertising materials mentioning features or use of this
   *    software must display the following acknowledgment:
   *    "This product includes software developed by the OpenSSL Project
   *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
   *
   * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
   *    endorse or promote products derived from this software without
   *    prior written permission. For written permission, please contact
   *    licensing@OpenSSL.org.
   *
   * 5. Products derived from this software may not be called "OpenSSL"
   *    nor may "OpenSSL" appear in their names without prior written
   *    permission of the OpenSSL Project.
   *
   * 6. Redistributions of any form whatsoever must retain the following
   *    acknowledgment:
   *    "This product includes software developed by the OpenSSL Project
   *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
   *
   * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
   * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
   * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
   * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
   * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
   * OF THE POSSIBILITY OF SUCH DAMAGE.
   * ====================================================================
   *
   * This product includes cryptographic software written by Eric Young
   * (eay@cryptsoft.com).  This product includes software written by Tim
   * Hudson (tjh@cryptsoft.com).
   *
   */
  
  #include "eng_int.h"
  #include <openssl/dso.h>
  
  /*
   * Shared libraries implementing ENGINEs for use by the "dynamic" ENGINE
   * loader should implement the hook-up functions with the following
   * prototypes.
   */
  
  /* Our ENGINE handlers */
  static int dynamic_init(ENGINE *e);
  static int dynamic_finish(ENGINE *e);
  static int dynamic_ctrl(ENGINE *e, int cmd, long i, void *p,
                          void (*f) (void));
  /* Predeclare our context type */
  typedef struct st_dynamic_data_ctx dynamic_data_ctx;
  /* The implementation for the important control command */
  static int dynamic_load(ENGINE *e, dynamic_data_ctx *ctx);
  
  #define DYNAMIC_CMD_SO_PATH             ENGINE_CMD_BASE
  #define DYNAMIC_CMD_NO_VCHECK           (ENGINE_CMD_BASE + 1)
  #define DYNAMIC_CMD_ID                  (ENGINE_CMD_BASE + 2)
  #define DYNAMIC_CMD_LIST_ADD            (ENGINE_CMD_BASE + 3)
  #define DYNAMIC_CMD_DIR_LOAD            (ENGINE_CMD_BASE + 4)
  #define DYNAMIC_CMD_DIR_ADD             (ENGINE_CMD_BASE + 5)
  #define DYNAMIC_CMD_LOAD                (ENGINE_CMD_BASE + 6)
  
  /* The constants used when creating the ENGINE */
  static const char *engine_dynamic_id = "dynamic";
  static const char *engine_dynamic_name = "Dynamic engine loading support";
  static const ENGINE_CMD_DEFN dynamic_cmd_defns[] = {
      {DYNAMIC_CMD_SO_PATH,
       "SO_PATH",
       "Specifies the path to the new ENGINE shared library",
       ENGINE_CMD_FLAG_STRING},
      {DYNAMIC_CMD_NO_VCHECK,
       "NO_VCHECK",
       "Specifies to continue even if version checking fails (boolean)",
       ENGINE_CMD_FLAG_NUMERIC},
      {DYNAMIC_CMD_ID,
       "ID",
       "Specifies an ENGINE id name for loading",
       ENGINE_CMD_FLAG_STRING},
      {DYNAMIC_CMD_LIST_ADD,
       "LIST_ADD",
       "Whether to add a loaded ENGINE to the internal list (0=no,1=yes,2=mandatory)",
       ENGINE_CMD_FLAG_NUMERIC},
      {DYNAMIC_CMD_DIR_LOAD,
       "DIR_LOAD",
       "Specifies whether to load from 'DIR_ADD' directories (0=no,1=yes,2=mandatory)",
       ENGINE_CMD_FLAG_NUMERIC},
      {DYNAMIC_CMD_DIR_ADD,
       "DIR_ADD",
       "Adds a directory from which ENGINEs can be loaded",
       ENGINE_CMD_FLAG_STRING},
      {DYNAMIC_CMD_LOAD,
       "LOAD",
       "Load up the ENGINE specified by other settings",
       ENGINE_CMD_FLAG_NO_INPUT},
      {0, NULL, NULL, 0}
  };
  
  /*
   * Loading code stores state inside the ENGINE structure via the "ex_data"
   * element. We load all our state into a single structure and use that as a
   * single context in the "ex_data" stack.
   */
  struct st_dynamic_data_ctx {
      /* The DSO object we load that supplies the ENGINE code */
      DSO *dynamic_dso;
      /*
       * The function pointer to the version checking shared library function
       */
      dynamic_v_check_fn v_check;
      /*
       * The function pointer to the engine-binding shared library function
       */
      dynamic_bind_engine bind_engine;
      /* The default name/path for loading the shared library */
      char *DYNAMIC_LIBNAME;
      /* Whether to continue loading on a version check failure */
      int no_vcheck;
      /* If non-NULL, stipulates the 'id' of the ENGINE to be loaded */
      char *engine_id;
      /*
       * If non-zero, a successfully loaded ENGINE should be added to the
       * internal ENGINE list. If 2, the add must succeed or the entire load
       * should fail.
       */
      int list_add_value;
      /* The symbol name for the version checking function */
      const char *DYNAMIC_F1;
      /* The symbol name for the "initialise ENGINE structure" function */
      const char *DYNAMIC_F2;
      /*
       * Whether to never use 'dirs', use 'dirs' as a fallback, or only use
       * 'dirs' for loading. Default is to use 'dirs' as a fallback.
       */
      int dir_load;
      /* A stack of directories from which ENGINEs could be loaded */
      STACK_OF(OPENSSL_STRING) *dirs;
  };
  
  /*
   * This is the "ex_data" index we obtain and reserve for use with our context
   * structure.
   */
  static int dynamic_ex_data_idx = -1;
  
  static void int_free_str(char *s)
  {
      OPENSSL_free(s);
  }
  
  /*
   * Because our ex_data element may or may not get allocated depending on
   * whether a "first-use" occurs before the ENGINE is freed, we have a memory
   * leak problem to solve. We can't declare a "new" handler for the ex_data as
   * we don't want a dynamic_data_ctx in *all* ENGINE structures of all types
   * (this is a bug in the design of CRYPTO_EX_DATA). As such, we just declare
   * a "free" handler and that will get called if an ENGINE is being destroyed
   * and there was an ex_data element corresponding to our context type.
   */
  static void dynamic_data_ctx_free_func(void *parent, void *ptr,
                                         CRYPTO_EX_DATA *ad, int idx, long argl,
                                         void *argp)
  {
      if (ptr) {
          dynamic_data_ctx *ctx = (dynamic_data_ctx *)ptr;
          DSO_free(ctx->dynamic_dso);
          OPENSSL_free(ctx->DYNAMIC_LIBNAME);
          OPENSSL_free(ctx->engine_id);
          sk_OPENSSL_STRING_pop_free(ctx->dirs, int_free_str);
          OPENSSL_free(ctx);
      }
  }
  
  /*
   * Construct the per-ENGINE context. We create it blindly and then use a lock
   * to check for a race - if so, all but one of the threads "racing" will have
   * wasted their time. The alternative involves creating everything inside the
   * lock which is far worse.
   */
  static int dynamic_set_data_ctx(ENGINE *e, dynamic_data_ctx **ctx)
  {
      dynamic_data_ctx *c = OPENSSL_zalloc(sizeof(*c));
  
      if (c == NULL) {
          ENGINEerr(ENGINE_F_DYNAMIC_SET_DATA_CTX, ERR_R_MALLOC_FAILURE);
          return 0;
      }
      c->dirs = sk_OPENSSL_STRING_new_null();
      if (c->dirs == NULL) {
          ENGINEerr(ENGINE_F_DYNAMIC_SET_DATA_CTX, ERR_R_MALLOC_FAILURE);
          OPENSSL_free(c);
          return 0;
      }
      c->DYNAMIC_F1 = "v_check";
      c->DYNAMIC_F2 = "bind_engine";
      c->dir_load = 1;
      CRYPTO_w_lock(CRYPTO_LOCK_ENGINE);
      if ((*ctx = (dynamic_data_ctx *)ENGINE_get_ex_data(e,
                                                         dynamic_ex_data_idx))
          == NULL) {
          /* Good, we're the first */
          ENGINE_set_ex_data(e, dynamic_ex_data_idx, c);
          *ctx = c;
          c = NULL;
      }
      CRYPTO_w_unlock(CRYPTO_LOCK_ENGINE);
      /*
       * If we lost the race to set the context, c is non-NULL and *ctx is the
       * context of the thread that won.
       */
      OPENSSL_free(c);
      return 1;
  }
  
  /*
   * This function retrieves the context structure from an ENGINE's "ex_data",
   * or if it doesn't exist yet, sets it up.
   */
  static dynamic_data_ctx *dynamic_get_data_ctx(ENGINE *e)
  {
      dynamic_data_ctx *ctx;
      if (dynamic_ex_data_idx < 0) {
          /*
           * Create and register the ENGINE ex_data, and associate our "free"
           * function with it to ensure any allocated contexts get freed when
           * an ENGINE goes underground.
           */
          int new_idx = ENGINE_get_ex_new_index(0, NULL, NULL, NULL,
                                                dynamic_data_ctx_free_func);
          if (new_idx == -1) {
              ENGINEerr(ENGINE_F_DYNAMIC_GET_DATA_CTX, ENGINE_R_NO_INDEX);
              return NULL;
          }
          CRYPTO_w_lock(CRYPTO_LOCK_ENGINE);
          /* Avoid a race by checking again inside this lock */
          if (dynamic_ex_data_idx < 0) {
              /* Good, someone didn't beat us to it */
              dynamic_ex_data_idx = new_idx;
              new_idx = -1;
          }
          CRYPTO_w_unlock(CRYPTO_LOCK_ENGINE);
          /*
           * In theory we could "give back" the index here if (new_idx>-1), but
           * it's not possible and wouldn't gain us much if it were.
           */
      }
      ctx = (dynamic_data_ctx *)ENGINE_get_ex_data(e, dynamic_ex_data_idx);
      /* Check if the context needs to be created */
      if ((ctx == NULL) && !dynamic_set_data_ctx(e, &ctx))
          /* "set_data" will set errors if necessary */
          return NULL;
      return ctx;
  }
  
  static ENGINE *engine_dynamic(void)
  {
      ENGINE *ret = ENGINE_new();
      if (ret == NULL)
          return NULL;
      if (!ENGINE_set_id(ret, engine_dynamic_id) ||
          !ENGINE_set_name(ret, engine_dynamic_name) ||
          !ENGINE_set_init_function(ret, dynamic_init) ||
          !ENGINE_set_finish_function(ret, dynamic_finish) ||
          !ENGINE_set_ctrl_function(ret, dynamic_ctrl) ||
          !ENGINE_set_flags(ret, ENGINE_FLAGS_BY_ID_COPY) ||
          !ENGINE_set_cmd_defns(ret, dynamic_cmd_defns)) {
          ENGINE_free(ret);
          return NULL;
      }
      return ret;
  }
  
  void ENGINE_load_dynamic(void)
  {
      ENGINE *toadd = engine_dynamic();
      if (!toadd)
          return;
      ENGINE_add(toadd);
      /*
       * If the "add" worked, it gets a structural reference. So either way, we
       * release our just-created reference.
       */
      ENGINE_free(toadd);
      /*
       * If the "add" didn't work, it was probably a conflict because it was
       * already added (eg. someone calling ENGINE_load_blah then calling
       * ENGINE_load_builtin_engines() perhaps).
       */
      ERR_clear_error();
  }
  
  static int dynamic_init(ENGINE *e)
  {
      /*
       * We always return failure - the "dyanamic" engine itself can't be used
       * for anything.
       */
      return 0;
  }
  
  static int dynamic_finish(ENGINE *e)
  {
      /*
       * This should never be called on account of "dynamic_init" always
       * failing.
       */
      return 0;
  }
  
  static int dynamic_ctrl(ENGINE *e, int cmd, long i, void *p, void (*f) (void))
  {
      dynamic_data_ctx *ctx = dynamic_get_data_ctx(e);
      int initialised;
  
      if (!ctx) {
          ENGINEerr(ENGINE_F_DYNAMIC_CTRL, ENGINE_R_NOT_LOADED);
          return 0;
      }
      initialised = ((ctx->dynamic_dso == NULL) ? 0 : 1);
      /* All our control commands require the ENGINE to be uninitialised */
      if (initialised) {
          ENGINEerr(ENGINE_F_DYNAMIC_CTRL, ENGINE_R_ALREADY_LOADED);
          return 0;
      }
      switch (cmd) {
      case DYNAMIC_CMD_SO_PATH:
          /* a NULL 'p' or a string of zero-length is the same thing */
          if (p && (strlen((const char *)p) < 1))
              p = NULL;
          OPENSSL_free(ctx->DYNAMIC_LIBNAME);
          if (p)
              ctx->DYNAMIC_LIBNAME = OPENSSL_strdup(p);
          else
              ctx->DYNAMIC_LIBNAME = NULL;
          return (ctx->DYNAMIC_LIBNAME ? 1 : 0);
      case DYNAMIC_CMD_NO_VCHECK:
          ctx->no_vcheck = ((i == 0) ? 0 : 1);
          return 1;
      case DYNAMIC_CMD_ID:
          /* a NULL 'p' or a string of zero-length is the same thing */
          if (p && (strlen((const char *)p) < 1))
              p = NULL;
          OPENSSL_free(ctx->engine_id);
          if (p)
              ctx->engine_id = OPENSSL_strdup(p);
          else
              ctx->engine_id = NULL;
          return (ctx->engine_id ? 1 : 0);
      case DYNAMIC_CMD_LIST_ADD:
          if ((i < 0) || (i > 2)) {
              ENGINEerr(ENGINE_F_DYNAMIC_CTRL, ENGINE_R_INVALID_ARGUMENT);
              return 0;
          }
          ctx->list_add_value = (int)i;
          return 1;
      case DYNAMIC_CMD_LOAD:
          return dynamic_load(e, ctx);
      case DYNAMIC_CMD_DIR_LOAD:
          if ((i < 0) || (i > 2)) {
              ENGINEerr(ENGINE_F_DYNAMIC_CTRL, ENGINE_R_INVALID_ARGUMENT);
              return 0;
          }
          ctx->dir_load = (int)i;
          return 1;
      case DYNAMIC_CMD_DIR_ADD:
          /* a NULL 'p' or a string of zero-length is the same thing */
          if (!p || (strlen((const char *)p) < 1)) {
              ENGINEerr(ENGINE_F_DYNAMIC_CTRL, ENGINE_R_INVALID_ARGUMENT);
              return 0;
          }
          {
              char *tmp_str = OPENSSL_strdup(p);
              if (!tmp_str) {
                  ENGINEerr(ENGINE_F_DYNAMIC_CTRL, ERR_R_MALLOC_FAILURE);
                  return 0;
              }
              sk_OPENSSL_STRING_insert(ctx->dirs, tmp_str, -1);
          }
          return 1;
      default:
          break;
      }
      ENGINEerr(ENGINE_F_DYNAMIC_CTRL, ENGINE_R_CTRL_COMMAND_NOT_IMPLEMENTED);
      return 0;
  }
  
  static int int_load(dynamic_data_ctx *ctx)
  {
      int num, loop;
      /* Unless told not to, try a direct load */
      if ((ctx->dir_load != 2) && (DSO_load(ctx->dynamic_dso,
                                            ctx->DYNAMIC_LIBNAME, NULL,
                                            0)) != NULL)
          return 1;
      /* If we're not allowed to use 'dirs' or we have none, fail */
      if (!ctx->dir_load || (num = sk_OPENSSL_STRING_num(ctx->dirs)) < 1)
          return 0;
      for (loop = 0; loop < num; loop++) {
          const char *s = sk_OPENSSL_STRING_value(ctx->dirs, loop);
          char *merge = DSO_merge(ctx->dynamic_dso, ctx->DYNAMIC_LIBNAME, s);
          if (!merge)
              return 0;
          if (DSO_load(ctx->dynamic_dso, merge, NULL, 0)) {
              /* Found what we're looking for */
              OPENSSL_free(merge);
              return 1;
          }
          OPENSSL_free(merge);
      }
      return 0;
  }
  
  static int dynamic_load(ENGINE *e, dynamic_data_ctx *ctx)
  {
      ENGINE cpy;
      dynamic_fns fns;
  
      if (ctx->dynamic_dso == NULL)
          ctx->dynamic_dso = DSO_new();
      if (ctx->dynamic_dso == NULL)
          return 0;
      if (!ctx->DYNAMIC_LIBNAME) {
          if (!ctx->engine_id)
              return 0;
          ctx->DYNAMIC_LIBNAME =
              DSO_convert_filename(ctx->dynamic_dso, ctx->engine_id);
      }
      if (!int_load(ctx)) {
          ENGINEerr(ENGINE_F_DYNAMIC_LOAD, ENGINE_R_DSO_NOT_FOUND);
          DSO_free(ctx->dynamic_dso);
          ctx->dynamic_dso = NULL;
          return 0;
      }
      /* We have to find a bind function otherwise it'll always end badly */
      if (!
          (ctx->bind_engine =
           (dynamic_bind_engine) DSO_bind_func(ctx->dynamic_dso,
                                               ctx->DYNAMIC_F2))) {
          ctx->bind_engine = NULL;
          DSO_free(ctx->dynamic_dso);
          ctx->dynamic_dso = NULL;
          ENGINEerr(ENGINE_F_DYNAMIC_LOAD, ENGINE_R_DSO_FAILURE);
          return 0;
      }
      /* Do we perform version checking? */
      if (!ctx->no_vcheck) {
          unsigned long vcheck_res = 0;
          /*
           * Now we try to find a version checking function and decide how to
           * cope with failure if/when it fails.
           */
          ctx->v_check =
              (dynamic_v_check_fn) DSO_bind_func(ctx->dynamic_dso,
                                                 ctx->DYNAMIC_F1);
          if (ctx->v_check)
              vcheck_res = ctx->v_check(OSSL_DYNAMIC_VERSION);
          /*
           * We fail if the version checker veto'd the load *or* if it is
           * deferring to us (by returning its version) and we think it is too
           * old.
           */
          if (vcheck_res < OSSL_DYNAMIC_OLDEST) {
              /* Fail */
              ctx->bind_engine = NULL;
              ctx->v_check = NULL;
              DSO_free(ctx->dynamic_dso);
              ctx->dynamic_dso = NULL;
              ENGINEerr(ENGINE_F_DYNAMIC_LOAD,
                        ENGINE_R_VERSION_INCOMPATIBILITY);
              return 0;
          }
      }
      /*
       * First binary copy the ENGINE structure so that we can roll back if the
       * hand-over fails
       */
      memcpy(&cpy, e, sizeof(ENGINE));
      /*
       * Provide the ERR, "ex_data", memory, and locking callbacks so the
       * loaded library uses our state rather than its own. FIXME: As noted in
       * engine.h, much of this would be simplified if each area of code
       * provided its own "summary" structure of all related callbacks. It
       * would also increase opaqueness.
       */
      fns.static_state = ENGINE_get_static_state();
      fns.lock_fns.lock_locking_cb = CRYPTO_get_locking_callback();
      fns.lock_fns.lock_add_lock_cb = CRYPTO_get_add_lock_callback();
      fns.lock_fns.dynlock_create_cb = CRYPTO_get_dynlock_create_callback();
      fns.lock_fns.dynlock_lock_cb = CRYPTO_get_dynlock_lock_callback();
      fns.lock_fns.dynlock_destroy_cb = CRYPTO_get_dynlock_destroy_callback();
      /*
       * Now that we've loaded the dynamic engine, make sure no "dynamic"
       * ENGINE elements will show through.
       */
      engine_set_all_null(e);
  
      /* Try to bind the ENGINE onto our own ENGINE structure */
      if (!ctx->bind_engine(e, ctx->engine_id, &fns)) {
          ctx->bind_engine = NULL;
          ctx->v_check = NULL;
          DSO_free(ctx->dynamic_dso);
          ctx->dynamic_dso = NULL;
          ENGINEerr(ENGINE_F_DYNAMIC_LOAD, ENGINE_R_INIT_FAILED);
          /* Copy the original ENGINE structure back */
          memcpy(e, &cpy, sizeof(ENGINE));
          return 0;
      }
      /* Do we try to add this ENGINE to the internal list too? */
      if (ctx->list_add_value > 0) {
          if (!ENGINE_add(e)) {
              /* Do we tolerate this or fail? */
              if (ctx->list_add_value > 1) {
                  /*
                   * Fail - NB: By this time, it's too late to rollback, and
                   * trying to do so allows the bind_engine() code to have
                   * created leaks. We just have to fail where we are, after
                   * the ENGINE has changed.
                   */
                  ENGINEerr(ENGINE_F_DYNAMIC_LOAD,
                            ENGINE_R_CONFLICTING_ENGINE_ID);
                  return 0;
              }
              /* Tolerate */
              ERR_clear_error();
          }
      }
      return 1;
  }
  