Fix concurrent nc_client_init() and nc_server_init()

src/session.c

@@ -2512,6 +2512,110 @@ nc_session_tls_crl_verify_post_handshake(void *tls_session, void *cert_store)
 
 #endif /* NC_ENABLED_SSH_TLS */
 
+/**
+ * @brief Initialize or destroy the global state of the libraries used by libnetconf2.
+ *
+ * @param[in] side Side that is being initialized/destroyed.
+ * @param[in] destroy Whether to destroy the global state instead of initializing it.
+ * @return 0 on success, -1 on error.
+ */
+static int
+nc_global_init_destroy(NC_SIDE side, int destroy)
+{
+#ifdef NC_ENABLED_SSH_TLS
+    /* lock protecting the init flags and the global init of the libraries, which is not thread-safe */
+    static pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;
+
+    /* whether the client/server side has the libraries initialized */
+    static int init_client = 0, init_server = 0;
+
+    int rc = 0, curl_inited = 0, tls_inited = 0, *inited;
+
+    inited = (side == NC_CLIENT) ? &init_client : &init_server;
+
+    /* GLOBAL INIT LOCK */
+    pthread_mutex_lock(&lock);
+
+    if (destroy) {
+        if (!*inited) {
+            /* this side has not initialized the libraries */
+            goto cleanup;
+        }
+        *inited = 0;
+
+        if (!init_client && !init_server) {
+            /* the last side using the libraries, destroy them in the reverse order */
+            ssh_finalize();
+            nc_tls_backend_destroy_wrap();
+            curl_global_cleanup();
+        }
+        goto cleanup;
+    }
+
+    if (init_client || init_server) {
+        /* the libraries are already initialized by the other side */
+        *inited = 1;
+        goto cleanup;
+    }
+
+    if (curl_global_init(CURL_GLOBAL_SSL | CURL_GLOBAL_ACK_EINTR)) {
+        ERR(NULL, "%s: failed to init CURL.", __func__);
+        rc = -1;
+        goto cleanup;
+    }
+    curl_inited = 1;
+
+    if (nc_tls_backend_init_wrap()) {
+        ERR(NULL, "%s: failed to init the SSL library backend.", __func__);
+        rc = -1;
+        goto cleanup;
+    }
+    tls_inited = 1;
+
+    /* optional for dynamic library, mandatory for static */
+    if (ssh_init()) {
+        ERR(NULL, "%s: failed to init libssh.", __func__);
+        rc = -1;
+        goto cleanup;
+    }
+
+    *inited = 1;
+
+cleanup:
+    if (rc) {
+        /* leave no library initialized behind */
+        if (tls_inited) {
+            nc_tls_backend_destroy_wrap();
+        }
+        if (curl_inited) {
+            curl_global_cleanup();
+        }
+    }
+
+    /* GLOBAL INIT UNLOCK */
+    pthread_mutex_unlock(&lock);
+
+    return rc;
+#else
+    (void)side;
+    (void)destroy;
+
+    return 0;
+#endif /* NC_ENABLED_SSH_TLS */
+}
+
+int
+nc_global_init(NC_SIDE side)
+{
+    return nc_global_init_destroy(side, 0);
+}
+
+void
+nc_global_destroy(NC_SIDE side)
+{
+    nc_global_init_destroy(side, 1);
+}
+
 API const char *
 nc_yang_module_dir(void)
 {

src/session_client.c

@@ -1908,18 +1908,7 @@ nc_session_ntf_thread_running(const struct nc_session *session)
 API int
 nc_client_init(void)
 {
-#ifdef NC_ENABLED_SSH_TLS
-    if (nc_tls_backend_init_wrap()) {
-        ERR(NULL, "%s: failed to init the SSL library backend.", __func__);
-        return -1;
-    }
-    if (ssh_init()) {
-        ERR(NULL, "%s: failed to init libssh.", __func__);
-        return -1;
-    }
-#endif
-
-    return 0;
+    return nc_global_init(NC_CLIENT);
 }
 
 API void
@@ -1931,9 +1920,9 @@ nc_client_destroy(void)
     nc_client_ch_del_bind(NULL, 0, 0);
     nc_client_ssh_destroy_opts();
     nc_client_tls_destroy_opts();
-    nc_tls_backend_destroy_wrap();
-    ssh_finalize();
 #endif /* NC_ENABLED_SSH_TLS */
+
+    nc_global_destroy(NC_CLIENT);
 }
 
 static NC_MSG_TYPE

src/session_p.h

@@ -1462,6 +1462,21 @@ int nc_poll(struct pollfd *pfd, uint16_t pfd_count, int timeout);
  */
 int nc_sock_configure_ka(int sock, const struct nc_keepalives *ka);
 
+/**
+ * @brief Initialize the global state of the libraries used by libnetconf2.
+ *
+ * @param[in] side Side that is being initialized.
+ * @return 0 on success, -1 on error.
+ */
+int nc_global_init(NC_SIDE side);
+
+/**
+ * @brief Destroy the global state of the libraries used by libnetconf2.
+ *
+ * @param[in] side Side that is being destroyed.
+ */
+void nc_global_destroy(NC_SIDE side);
+
 struct nc_session *nc_new_session(NC_SIDE side, int shared_ti);
 
 int nc_session_rpc_lock(struct nc_session *session, int timeout, const char *func);

src/session_server.c

@@ -1524,6 +1524,8 @@ nc_server_init_rwlock(pthread_rwlock_t *rwlock)
 API int
 nc_server_init(void)
 {
+    int glob_inited = 0;
+
 #ifdef NC_ENABLED_SSH_TLS
     int r;
 #endif /* NC_ENABLED_SSH_TLS */
@@ -1547,23 +1549,13 @@ nc_server_init(void)
     ATOMIC_STORE_RELAXED(server_opts.config->refcount, 1);
     ATOMIC_STORE_RELAXED(server_opts.idle_timeout, 0);
 
-#ifdef NC_ENABLED_SSH_TLS
-    if (curl_global_init(CURL_GLOBAL_SSL | CURL_GLOBAL_ACK_EINTR)) {
-        ERR(NULL, "%s: failed to init CURL.", __func__);
-        goto error;
-    }
-
-    if (nc_tls_backend_init_wrap()) {
-        ERR(NULL, "%s: failed to init the SSL library backend.", __func__);
-        goto error;
-    }
-
-    /* optional for dynamic library, mandatory for static */
-    if (ssh_init()) {
-        ERR(NULL, "%s: failed to init libssh.", __func__);
+    /* initialize the global state of the used libraries, shared with the client side */
+    if (nc_global_init(NC_SERVER)) {
         goto error;
     }
+    glob_inited = 1;
 
+#ifdef NC_ENABLED_SSH_TLS
     if ((r = pthread_mutex_init(&server_opts.cert_exp_notif.lock, NULL))) {
         ERR(NULL, "%s: failed to init certificate expiration notification thread lock(%s).", __func__, strerror(r));
         goto error;
@@ -1584,6 +1576,9 @@ nc_server_init(void)
     nc_server_config_release(server_opts.config);
     server_opts.config = NULL;
     ATOMIC_STORE_RELAXED(server_opts.new_session_id, 0);
+    if (glob_inited) {
+        nc_global_destroy(NC_SERVER);
+    }
     return -1;
 }
 
@@ -1701,17 +1696,15 @@ nc_server_destroy(void)
     nc_server_config_release(config);
 
 #ifdef NC_ENABLED_SSH_TLS
-    curl_global_cleanup();
-    nc_tls_backend_destroy_wrap();
-    ssh_finalize();
-
     /* close the TLS keylog file */
     if (server_opts.tls_keylog_file) {
         fclose(server_opts.tls_keylog_file);
         server_opts.tls_keylog_file = NULL;
     }
 #endif /* NC_ENABLED_SSH_TLS */
 
+    nc_global_destroy(NC_SERVER);
+
 cleanup:
     if (opts_locked) {
         nc_rwlock_unlock(&server_opts.opts_lock, __func__);

tests/test_thread_messages.c

@@ -116,6 +116,7 @@ server_thread(void *arg)
     pthread_barrier_wait(&barrier);
 
     nc_server_notif_free(notif);
+    nc_assert(!nc_server_destroy());
     return arg;
 }
 
@@ -227,6 +228,7 @@ main(void)
 
     /* cleanup */
     nc_session_free(sess, NULL);
+    nc_client_destroy();
     ly_ctx_destroy(server_ctx);
     ly_ctx_destroy(client_ctx);
     for (uint8_t i = 0; i < 4; i++) {