From 8b7b7b0f605c2b961c7bac7ae8c2880301168e4c Mon Sep 17 00:00:00 2001
From: Olof hagsand <olof@hagsand.se>
Date: Tue, 13 Aug 2019 13:21:11 +0200
Subject: [PATCH] * RESTCONF "content" query parameter supported * New
 clixon-lib@2019-08-13.yang revision * Bugfix: If `ietf-netconf.yang` was
 imported from any yang module, client/backend communication stops working.

---
 CHANGELOG.md                                  |  5 +
 apps/backend/backend_client.c                 | 93 +++++++++++++++++-
 apps/backend/backend_main.c                   |  9 +-
 apps/cli/cli_main.c                           |  6 ++
 apps/netconf/netconf_main.c                   |  6 ++
 apps/restconf/restconf_lib.c                  | 23 +++++
 apps/restconf/restconf_lib.h                  | 12 +++
 apps/restconf/restconf_main.c                 |  6 ++
 apps/restconf/restconf_methods_get.c          | 35 ++++++-
 example/main/example_backend.c                | 94 +++++++++++++-----
 lib/clixon/clixon_netconf_lib.h               |  2 +
 lib/clixon/clixon_proto_client.h              |  1 +
 lib/src/clixon_netconf_lib.c                  | 97 +++++++++++++++----
 lib/src/clixon_proto_client.c                 | 79 +++++++++++++++
 lib/src/clixon_xml_map.c                      |  2 +-
 test/test_restconf.sh                         |  4 +-
 test/test_restconf_jukebox.sh                 | 43 +++++++-
 test/test_yang.sh                             | 16 +--
 yang/clixon/Makefile.in                       |  2 +-
 ...-06-05.yang => clixon-lib@2019-08-13.yang} | 34 +++++++
 20 files changed, 507 insertions(+), 62 deletions(-)
 rename yang/clixon/{clixon-lib@2019-06-05.yang => clixon-lib@2019-08-13.yang} (67%)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index efc0cf5b..fdb7ae89 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,7 @@
 * Restconf RFC 8040 increased feature compliance
   * RESTCONF PATCH (plain patch) is being implemented according to RFC 8040 Section 4.6.1
     * Note RESTCONF plain patch is different from RFC 8072 "YANG Patch Media Type" which is not implemented
+  * RESTCONF "content" query parameter supported
   * RESTCONF "insert" and "point" query parameters supported
     * Applies to ordered-by-user leaf and leaf-lists
   * RESTCONF PUT/POST erroneously returned 200 OK. Instead restconf now returns:
@@ -25,6 +26,8 @@
   * The main example explains how to implement a Yang extension in a backend plugin.
 
 ### API changes on existing features (you may need to change your code)
+* New clixon-lib@2019-08-13.yang revision
+  * Added new rpc: `get-state` to get only state info in the internal Restconf/backend communication
 * Netconf edit-config "operation" attribute namespace check is enforced
   * This is enforced: `<a xmlns="uri:example" nc:operation="merge" xmlns:nc="urn:ietf:params:xml:ns:netconf:base:1.0">
   * This was previously allowed: `<a xmlns="uri:example" operation="merge">
@@ -51,6 +54,8 @@
 * pseudo-plugin added, to enable callbacks also for main programs. Useful for extensions
 
 ### Corrected Bugs
+* If `ietf-netconf.yang` was imported from any yang module, client/backend communication stops working.
+  * Fixed by adding supported netconf features before loading other yang modules
 * RESTCONF JSON identity had wrong namespace in sub-objetcs
   * Showed if you GET an object with JSON encoding that have identities
 * Fixed Segv in nacm write when MERGE and creating object
diff --git a/apps/backend/backend_client.c b/apps/backend/backend_client.c
index 07329adc..1d532db1 100644
--- a/apps/backend/backend_client.c
+++ b/apps/backend/backend_client.c
@@ -942,6 +942,94 @@ from_client_get(clicon_handle h,
     return retval;
 }
 
+/*! Retrieve device state information only
+ * 
+ * This is a CLIXON specific RPC
+ * @param[in]  h       Clicon handle 
+ * @param[in]  xe      Request: <rpc><xn></rpc> 
+ * @param[out] cbret   Return xml tree, eg <rpc-reply>..., <rpc-error.. 
+ * @param[in]  arg     client-entry
+ * @param[in]  regarg  User argument given at rpc_callback_register() 
+ * @retval     0       OK
+ * @retval    -1       Error
+ *
+ * @see from_client_get
+ */
+static int
+from_client_get_state(clicon_handle h,
+		      cxobj        *xe,
+		      cbuf         *cbret,
+		      void         *arg, 
+		      void         *regarg)
+{
+    int     retval = -1;
+    cxobj  *xfilter;
+    char   *xpath = "/";
+    cxobj  *xret = NULL;
+    int     ret;
+    cxobj **xvec = NULL;
+    size_t  xlen;    
+    cxobj  *xnacm = NULL;
+    char   *username;
+    cvec   *nsc = NULL; /* Create a netconf namespace context from filter */
+    
+    username = clicon_username_get(h);
+    if ((xfilter = xml_find(xe, "filter")) != NULL){
+	if ((xpath = xml_find_value(xfilter, "select"))==NULL)
+	    xpath="/";
+	/* Create namespace context for xpath from <filter>
+	 *  The set of namespace declarations are those in scope on the
+	 * <filter> element.
+	 */
+	else
+	    if (xml_nsctx_node(xfilter, &nsc) < 0)
+		goto done;
+    }
+    /* Get state data from plugins as defined by plugin_statedata(), if any */
+    clicon_err_reset();
+    if ((ret = client_statedata(h, xpath, nsc, &xret)) < 0)
+	goto done;
+    if (ret == 0){ /* Error from callback (error in xret) */
+	if (clicon_xml2cbuf(cbret, xret, 0, 0) < 0)
+	    goto done;
+	goto ok;
+    }
+    /* Pre-NACM access step */
+    if ((ret = nacm_access_pre(h, username, NACM_DATA, &xnacm)) < 0)
+	goto done;
+    if (ret == 0){ /* Do NACM validation */
+	if (xpath_vec_nsc(xret, nsc, "%s", &xvec, &xlen, xpath?xpath:"/") < 0)
+	    goto done;
+	/* NACM datanode/module read validation */
+	if (nacm_datanode_read(xret, xvec, xlen, username, xnacm) < 0) 
+	    goto done;
+    }
+    cprintf(cbret, "<rpc-reply>");     /* OK */
+    if (xret==NULL)
+	cprintf(cbret, "<data/>");
+    else{
+	if (xml_name_set(xret, "data") < 0)
+	    goto done;
+	if (clicon_xml2cbuf(cbret, xret, 0, 0) < 0)
+	    goto done;
+    }
+    cprintf(cbret, "</rpc-reply>");
+ ok:
+    retval = 0;
+ done:
+    clicon_debug(1, "%s retval:%d", __FUNCTION__, retval);
+    if (xnacm)
+	xml_free(xnacm);
+    if (xvec)
+	free(xvec);
+    if (nsc)
+	xml_nsctx_free(nsc);
+    if (xret)
+	xml_free(xret);
+    return retval;
+}
+
+
 /*! Request graceful termination of a NETCONF session.
  * @param[in]  h       Clicon handle 
  * @param[in]  xe      Request: <rpc><xn></rpc> 
@@ -1283,7 +1371,7 @@ from_client_msg(clicon_handle        h,
 	    goto reply; /* Dont quit here on user callbacks */
 	}
 	if (ret == 0){ /* not handled by callback */
-	    if (netconf_operation_failed(cbret, "application", "Callback not recognized")< 0)
+	    if (netconf_operation_not_supported(cbret, "application", "RPC operation not supported")< 0)
 		goto done;
 	    goto reply;
 	}
@@ -1424,6 +1512,9 @@ backend_rpc_init(clicon_handle h)
 		      "urn:ietf:params:xml:ns:netmod:notification", "create-subscription") < 0)
 	goto done;
     /* Clixon RPC */
+    if (rpc_callback_register(h, from_client_get_state, NULL,
+			      "http://clicon.org/lib", "get-state") < 0)
+	goto done;
     if (rpc_callback_register(h, from_client_debug, NULL,
 			      "http://clicon.org/lib", "debug") < 0)
 	goto done;
diff --git a/apps/backend/backend_main.c b/apps/backend/backend_main.c
index 26fb145b..5a18f89f 100644
--- a/apps/backend/backend_main.c
+++ b/apps/backend/backend_main.c
@@ -570,6 +570,12 @@ main(int    argc,
     if (xmldb_connect(h) < 0)
 	goto done;
 
+    /* Add (hardcoded) netconf features in case ietf-netconf loaded here
+     * Otherwise it is loaded in netconf_module_load below
+     */
+    if (netconf_module_features(h) < 0)
+	goto done;
+
     /* Create top-level yang spec and store as option */
     if ((yspec = yspec_new()) == NULL)
 	goto done;
@@ -601,7 +607,8 @@ main(int    argc,
      /* Load yang module library, RFC7895 */
     if (yang_modules_init(h) < 0)
 	goto done;
-    /* Add netconf yang spec, used by netconf client and as internal protocol */
+    /* Add netconf yang spec, used by netconf client and as internal protocol 
+     */
     if (netconf_module_load(h) < 0)
 	goto done;
     /* Load yang restconf module */
diff --git a/apps/cli/cli_main.c b/apps/cli/cli_main.c
index 4651c5fc..d44973e4 100644
--- a/apps/cli/cli_main.c
+++ b/apps/cli/cli_main.c
@@ -472,6 +472,12 @@ main(int argc, char **argv)
 	clixon_plugins_load(h, CLIXON_PLUGIN_INIT, dir, NULL) < 0)
 	goto done;
 
+    /* Add (hardcoded) netconf features in case ietf-netconf loaded here
+     * Otherwise it is loaded in netconf_module_load below
+     */
+    if (netconf_module_features(h) < 0)
+	goto done;
+
     /* Create top-level and store as option */
     if ((yspec = yspec_new()) == NULL)
 	goto done;
diff --git a/apps/netconf/netconf_main.c b/apps/netconf/netconf_main.c
index 32e81496..f1fadb92 100644
--- a/apps/netconf/netconf_main.c
+++ b/apps/netconf/netconf_main.c
@@ -484,6 +484,12 @@ main(int    argc,
     /* Access the remaining argv/argc options (after --) w clicon-argv_get() */
     clicon_argv_set(h, argv0, argc, argv);
 
+    /* Add (hardcoded) netconf features in case ietf-netconf loaded here
+     * Otherwise it is loaded in netconf_module_load below
+     */
+    if (netconf_module_features(h) < 0)
+	goto done;
+
     /* Create top-level yang spec and store as option */
     if ((yspec = yspec_new()) == NULL)
 	goto done;
diff --git a/apps/restconf/restconf_lib.c b/apps/restconf/restconf_lib.c
index ddde425e..b4a245db 100644
--- a/apps/restconf/restconf_lib.c
+++ b/apps/restconf/restconf_lib.c
@@ -143,6 +143,7 @@ static const map_str2int http_reason_phrase_map[] = {
 };
 
 /* See RFC 8040
+ * @see restconf_media_str2int
  */
 static const map_str2int http_media_map[] = {
     {"application/yang-data+xml",     YANG_DATA_XML},
@@ -152,6 +153,16 @@ static const map_str2int http_media_map[] = {
     {NULL,                            -1}
 };
 
+/* See RFC 8040 4.8.1
+ * @see query_content_str2int
+ */
+static const map_str2int query_content_map[] = {
+    {"config",     CONTENT_CONFIG},
+    {"nonconfig",  CONTENT_NONCONFIG},
+    {"all",        CONTENT_ALL},
+    {NULL,        -1}
+};
+
 int
 restconf_err2code(char *tag)
 {
@@ -176,6 +187,18 @@ restconf_media_int2str(restconf_media media)
     return clicon_int2str(http_media_map, media);
 }
 
+const query_content
+query_content_str2int(char *str)
+{
+    return clicon_str2int(query_content_map, str);
+}
+
+const char *
+query_content_int2str(query_content nr)
+{
+    return clicon_int2str(query_content_map, nr);
+}
+
 /*! Return media_in from Content-Type, -1 if not found or unrecognized
  * @note media-type syntax does not support parameters
  * @see RFC7231 Sec 3.1.1.1 for media-type syntax type:
diff --git a/apps/restconf/restconf_lib.h b/apps/restconf/restconf_lib.h
index 6c4a2613..a7da11d5 100644
--- a/apps/restconf/restconf_lib.h
+++ b/apps/restconf/restconf_lib.h
@@ -57,6 +57,16 @@ enum restconf_media{
 };
 typedef enum restconf_media restconf_media;
 
+/*! Content query parameter RFC 8040 Sec 4.8.1 
+ */
+enum query_content{
+    CONTENT_CONFIG,
+    CONTENT_NONCONFIG,
+    CONTENT_ALL         /* default */
+
+};
+typedef enum query_content query_content;
+
 /*
  * Prototypes (also in clixon_restconf.h)
  */
@@ -66,6 +76,8 @@ const char *restconf_code2reason(int code);
 const restconf_media restconf_media_str2int(char *media);
 const char *restconf_media_int2str(restconf_media media);
 restconf_media restconf_content_type(FCGX_Request *r);
+const query_content query_content_str2int(char *str);
+const char *query_content_int2str(query_content nr);
 int restconf_badrequest(FCGX_Request *r);
 int restconf_unauthorized(FCGX_Request *r);
 int restconf_forbidden(FCGX_Request *r);
diff --git a/apps/restconf/restconf_main.c b/apps/restconf/restconf_main.c
index 31177590..eb93c6eb 100644
--- a/apps/restconf/restconf_main.c
+++ b/apps/restconf/restconf_main.c
@@ -695,6 +695,12 @@ main(int    argc,
     /* Access the remaining argv/argc options (after --) w clicon-argv_get() */
     clicon_argv_set(h, argv0, argc, argv);
     
+    /* Add (hardcoded) netconf features in case ietf-netconf loaded here
+     * Otherwise it is loaded in netconf_module_load below
+     */
+    if (netconf_module_features(h) < 0)
+	goto done;
+
     /* Create top-level yang spec and store as option */
     if ((yspec = yspec_new()) == NULL)
 	goto done;
diff --git a/apps/restconf/restconf_methods_get.c b/apps/restconf/restconf_methods_get.c
index 1f7e8554..dc9f5918 100644
--- a/apps/restconf/restconf_methods_get.c
+++ b/apps/restconf/restconf_methods_get.c
@@ -114,12 +114,31 @@ api_data_get2(clicon_handle h,
     int        ret;
     char      *namespace = NULL;
     cvec      *nsc = NULL;
+    char      *str;
+    query_content content = CONTENT_ALL;
     
     clicon_debug(1, "%s", __FUNCTION__);
     if ((yspec = clicon_dbspec_yang(h)) == NULL){
 	clicon_err(OE_FATAL, 0, "No DB_SPEC");
 	goto done;
     }
+    /* Check for content attribute */
+    if ((str = cvec_find_str(qvec, "content")) != NULL){
+	clicon_debug(1, "%s content=%s", __FUNCTION__, str);
+	if ((content = query_content_str2int(str)) == -1){
+	    if (netconf_bad_attribute_xml(&xerr, "application",
+					  "<bad-attribute>content</bad-attribute>", "Unrecognized value of content attribute") < 0)
+		goto done;
+	    if ((xe = xpath_first(xerr, "rpc-error")) == NULL){
+		clicon_err(OE_XML, EINVAL, "rpc-error not found (internal error)");
+		goto done;
+	    }
+	    if (api_return_err(h, r, xe, pretty, media_out, 0) < 0)
+		goto done;
+	    goto ok;
+	}
+    }
+
     if ((cbpath = cbuf_new()) == NULL)
         goto done;
     cprintf(cbpath, "/");
@@ -144,7 +163,21 @@ api_data_get2(clicon_handle h,
      * xpath expressions */
     if ((nsc = xml_nsctx_init(NULL, namespace)) == NULL)
 	goto done;
-    if (clicon_rpc_get(h, xpath, namespace, &xret) < 0){
+    switch (content){
+    case CONTENT_CONFIG:
+	ret = clicon_rpc_get_config(h, "running", xpath, namespace, &xret);
+	break;
+    case CONTENT_NONCONFIG:
+	ret = clicon_rpc_get_state(h, xpath, namespace, &xret);
+	break;
+    case CONTENT_ALL:
+	ret = clicon_rpc_get(h, xpath, namespace, &xret);
+	break;
+    default:
+	clicon_err(OE_XML, EINVAL, "Invalid content attribute %d", content);
+	break;
+    }
+    if (ret < 0){
 	if (netconf_operation_failed_xml(&xerr, "protocol", clicon_err_reason) < 0)
 	    goto done;
 	if ((xe = xpath_first(xerr, "rpc-error")) == NULL){
diff --git a/example/main/example_backend.c b/example/main/example_backend.c
index 647e892b..234c8d92 100644
--- a/example/main/example_backend.c
+++ b/example/main/example_backend.c
@@ -31,6 +31,12 @@
 
   ***** END LICENSE BLOCK *****
 
+  * The example have the following optional arguments that you can pass as 
+  * argc/argv after -- in clixon_backend:
+  *  -r  enable the reset function 
+  *  -s  enable the state function
+  *  -u  enable upgrade function - auto-upgrade testing
+  *  -t  enable transaction logging (cal syslog for every transaction)
  */
 #include <stdio.h>
 #include <stdlib.h>
@@ -284,7 +290,7 @@ example_copy_extra(clicon_handle h,            /* Clicon handle */
             type string;
          }
        }
- * This yang snippet is present in clixon-example.yang for exampl.
+ * This yang snippet is present in clixon-example.yang for example.
  */
 int 
 example_statedata(clicon_handle h, 
@@ -300,9 +306,12 @@ example_statedata(clicon_handle h,
     cxobj  *xt = NULL;
     char   *name;
     cvec   *nsc1 = NULL;
+    cvec   *nsc2 = NULL;
+    yang_stmt *yspec = NULL;
 
     if (!_state)
 	goto ok;
+    yspec = clicon_dbspec_yang(h);
     
     /* Example of statedata, in this case merging state data with 
      * state information. In this case adding dummy interface operation state
@@ -311,37 +320,75 @@ example_statedata(clicon_handle h,
     if (xmldb_get0(h, "running", nsc, xpath, 1, &xt, NULL) < 0)
 	goto done;
 
-    /* Here a separate namespace context nsc1 is created. The original nsc 
-     * created by the system cannot be used trivially, since we dont know
-     * the prefixes, although we could by a complex mechanism find the prefix 
-     * (if it exists) and use that when creating our xpath.
-     * But it is easier creating a new namespace context nsc1.
-     */
-    if ((nsc1 = xml_nsctx_init(NULL, "urn:ietf:params:xml:ns:yang:ietf-interfaces")) == NULL)
-	goto done;
-    if (xpath_vec_nsc(xt, nsc1, "/interfaces/interface/name", &xvec, &xlen) < 0)
-       goto done;
-   if (xlen){
-       cprintf(cb, "<interfaces xmlns=\"urn:ietf:params:xml:ns:yang:ietf-interfaces\">");
-       for (i=0; i<xlen; i++){
-	   name = xml_body(xvec[i]);
-	   cprintf(cb, "<interface><name>%s</name><oper-status>up</oper-status></interface>", name);
-       }
-       cprintf(cb, "</interfaces>");
-       if (xml_parse_string(cbuf_get(cb), NULL, &xstate) < 0)
-	   goto done;
-   }
-    if (xml_parse_string("<state xmlns=\"urn:example:clixon\">"
+    if (yang_find_module_by_namespace(yspec, "urn:ietf:params:xml:ns:yang:ietf-interfaces") != NULL){
+	/* Here a separate namespace context nsc1 is created. The original nsc 
+	 * created by the system cannot be used trivially, since we dont know
+	 * the prefixes, although we could by a complex mechanism find the prefix 
+	 * (if it exists) and use that when creating our xpath.
+	 * But it is easier creating a new namespace context nsc1.
+	 */
+	if ((nsc1 = xml_nsctx_init(NULL, "urn:ietf:params:xml:ns:yang:ietf-interfaces")) == NULL)
+	    goto done;
+	if (xpath_vec_nsc(xt, nsc1, "/interfaces/interface/name", &xvec, &xlen) < 0)
+	    goto done;
+	if (xlen){
+	    cprintf(cb, "<interfaces xmlns=\"urn:ietf:params:xml:ns:yang:ietf-interfaces\">");
+	    for (i=0; i<xlen; i++){
+		name = xml_body(xvec[i]);
+		cprintf(cb, "<interface><name>%s</name><oper-status>up</oper-status></interface>", name);
+	    }
+	    cprintf(cb, "</interfaces>");
+	    if (xml_parse_string(cbuf_get(cb), NULL, &xstate) < 0)
+		goto done;
+	}
+    }
+   /* State in test_yang.sh , test_restconf.sh and test_order.sh */
+   if (yang_find_module_by_namespace(yspec, "urn:example:clixon") != NULL){
+       if (xml_parse_string("<state xmlns=\"urn:example:clixon\">"
 			 "<op>42</op>"
 			 "<op>41</op>"
 			 "<op>43</op>" /* should not be ordered */
 			 "</state>", NULL, &xstate) < 0)
-	goto done;
+	goto done; /* For the case when urn:example:clixon is not loaded */
+   }
+    /* Event state from RFC8040 Appendix B.3.1 
+     * Note: (1) order is by-system so is different, 
+     *       (2) event-count is XOR on name, so is not 42 and 4
+     */
+   if (yang_find_module_by_namespace(yspec, "urn:example:events") != NULL){
+       if ((nsc2 = xml_nsctx_init(NULL, "urn:example:events")) == NULL)
+	   goto done;
+       if (xvec){
+	   free(xvec);
+	   xvec = NULL;
+       }
+       if (xpath_vec_nsc(xt, nsc2, "/events/event/name", &xvec, &xlen) < 0)
+	   goto done;
+       if (xlen){
+	   int j = 0;
+	   int c;
+	   cprintf(cb, "<events xmlns=\"urn:example:events\">");
+	   
+	   for (i=0; i<xlen; i++){
+	       name = xml_body(xvec[i]);
+	       c = 0;
+	       for (j=0; j<strlen(name); j++)
+		   c ^= name[j];
+	       cprintf(cb, "<event><name>%s</name><event-count>%d</event-count></event>", name, c);
+	   }
+	   cprintf(cb, "</events>");
+	   if (xml_parse_string(cbuf_get(cb), NULL, &xstate) < 0)
+	       goto done;
+       }
+   }
+
  ok:
     retval = 0;
  done:
     if (nsc1)
 	xml_nsctx_free(nsc1);
+    if (nsc2)
+	xml_nsctx_free(nsc2);
     if (xt)
 	xml_free(xt);
     if (cb)
@@ -389,7 +436,6 @@ example_extension(clicon_handle h,
     return retval;
 }
 
-
 /*! Testcase upgrade function moving interfaces-state to interfaces
  * @param[in]  h       Clicon handle 
  * @param[in]  xn      XML tree to be updated
diff --git a/lib/clixon/clixon_netconf_lib.h b/lib/clixon/clixon_netconf_lib.h
index 83fc2117..ccd9b528 100644
--- a/lib/clixon/clixon_netconf_lib.h
+++ b/lib/clixon/clixon_netconf_lib.h
@@ -47,6 +47,7 @@ int netconf_invalid_value_xml(cxobj **xret, char *type, char *message);
 int netconf_too_big(cbuf *cb, char *type, char *message);
 int netconf_missing_attribute(cbuf *cb,	char *type, char *info, char *message);
 int netconf_bad_attribute(cbuf *cb, char *type, char *info, char *message);
+int netconf_bad_attribute_xml(cxobj **xret, char *type, char *info, char *message);
 int netconf_unknown_attribute(cbuf *cb,	char *type, char *info, char *message);
 int netconf_missing_element(cbuf *cb, char *type, char *element, char *message);
 int netconf_missing_element_xml(cxobj **xret, char *type, char *element, char *message);
@@ -72,6 +73,7 @@ int netconf_malformed_message_xml(cxobj **xret, char *message);
 int netconf_data_not_unique_xml(cxobj **xret, cxobj *x,	cvec *cvk);
 int netconf_minmax_elements_xml(cxobj **xret, cxobj *x, int max);
 int netconf_trymerge(cxobj *x, yang_stmt *yspec, cxobj **xret);
+int netconf_module_features(clicon_handle h);
 int netconf_module_load(clicon_handle h);
 char *netconf_db_find(cxobj *xn, char *name);
 int netconf_err2cb(cxobj *xerr, cbuf **cberr);
diff --git a/lib/clixon/clixon_proto_client.h b/lib/clixon/clixon_proto_client.h
index 0ac3783b..d49d1314 100644
--- a/lib/clixon/clixon_proto_client.h
+++ b/lib/clixon/clixon_proto_client.h
@@ -53,6 +53,7 @@ int clicon_rpc_delete_config(clicon_handle h, char *db);
 int clicon_rpc_lock(clicon_handle h, char *db);
 int clicon_rpc_unlock(clicon_handle h, char *db);
 int clicon_rpc_get(clicon_handle h, char *xpath, char *namespace, cxobj **xret);
+int clicon_rpc_get_state(clicon_handle h, char *xpath, char *namespace, cxobj **xret);
 int clicon_rpc_close_session(clicon_handle h);
 int clicon_rpc_kill_session(clicon_handle h, int session_id);
 int clicon_rpc_validate(clicon_handle h, char *db);
diff --git a/lib/src/clixon_netconf_lib.c b/lib/src/clixon_netconf_lib.c
index bb28debf..c237cc00 100644
--- a/lib/src/clixon_netconf_lib.c
+++ b/lib/src/clixon_netconf_lib.c
@@ -271,34 +271,67 @@ netconf_bad_attribute(cbuf *cb,
 		      char *info,
 		      char *message)
 {
-    int   retval = -1;
-    char *encstr = NULL;
+    int    retval = -1;
+    cxobj *xret = NULL;
 
-    if (cprintf(cb, "<rpc-reply><rpc-error>"
-		"<error-type>%s</error-type>"
-		"<error-tag>bad-attribute</error-tag>"
-		"<error-info>%s</error-info>"
-		"<error-severity>error</error-severity>",
-		type, info) <0)
-	goto err;
+    if (netconf_bad_attribute_xml(&xret, type, info, message) < 0)
+	goto done;
+    if (clicon_xml2cbuf(cb, xret, 0, 0) < 0)
+	goto done;
+    retval = 0;
+ done:
+    if (xret)
+	xml_free(xret);
+    return retval;
+}
+
+/*! Create Netconf bad-attribute error XML tree according to RFC 6241 App A
+ *
+ * An attribute value is not correct; e.g., wrong type,
+ * out of range, pattern mismatch.
+ * @param[out] xret    Error XML tree. Free with xml_free after use
+ * @param[in]  type    Error type: "rpc", "application" or "protocol"
+ * @param[in]  info    bad-attribute or bad-element xml
+ * @param[in]  message Error message (will be XML encoded)
+ */
+int
+netconf_bad_attribute_xml(cxobj **xret,
+			  char   *type,
+			  char   *info,
+			  char   *message)
+{
+    int   retval = -1;
+    cxobj *xerr = NULL;
+    char  *encstr = NULL;
+
+    if (*xret == NULL){
+	if ((*xret = xml_new("rpc-reply", NULL, NULL)) == NULL)
+	    goto done;
+    }
+    else if (xml_name_set(*xret, "rpc-reply") < 0)
+	goto done;
+    if ((xerr = xml_new("rpc-error", *xret, NULL)) == NULL)
+	goto done;
+    if (xml_parse_va(&xerr, NULL, "<error-type>%s</error-type>"
+		     "<error-tag>bad-attribute</error-tag>"
+		     "<error-info>%s</error-info>"
+		     "<error-severity>error</error-severity>", type, info) < 0)
+	goto done;
     if (message){
 	if (xml_chardata_encode(&encstr, "%s", message) < 0)
 	    goto done;
-	if (cprintf(cb, "<error-message>%s</error-message>", encstr) < 0)
-	    goto err;
+	if (xml_parse_va(&xerr, NULL, "<error-message>%s</error-message>",
+			 encstr) < 0)
+	    goto done;
     }
-    if (cprintf(cb, "</rpc-error></rpc-reply>") <0)
-	goto err;
     retval = 0;
  done:
     if (encstr)
 	free(encstr);
     return retval;
- err:
-    clicon_err(OE_XML, errno, "cprintf");
-    goto done;
 }
 
+
 /*! Create Netconf unknwon-attribute error XML tree according to RFC 6241 App A
  *
  * An unexpected attribute is present.
@@ -462,6 +495,7 @@ netconf_bad_element(cbuf *cb,
 	xml_free(xret);
     return retval;
 }
+
 int
 netconf_bad_element_xml(cxobj **xret,
 			char   *type,
@@ -1208,19 +1242,26 @@ netconf_trymerge(cxobj       *x,
 }
 
 /*! Load ietf netconf yang module and set enabled features
- * The features added are (in order):
+ *
+ * This function should be called after options loaded but before yang modules.
+ * (a yang module may import ietf-netconf and then features must be set)
+ * @param[in] h  Clixon handle
+ * @retval    0  OK
+ * @retval   -1  Error
+ * The features added are (in order) (numbers are section# in RFC6241):
  *   candidate (8.3)
  *   validate (8.6)
  *   startup (8.7)
  *   xpath (8.9)
+ * @see netconf_module_load  that is called later
  */
 int
-netconf_module_load(clicon_handle h)
+netconf_module_features(clicon_handle h)
 {
     int        retval = -1;
     cxobj     *xc;
     yang_stmt *yspec;
-
+    
     yspec = clicon_dbspec_yang(h);
     if ((xc = clicon_conf_xml(h)) == NULL){
 	clicon_err(OE_CFG, ENOENT, "Clicon configuration not loaded");
@@ -1233,6 +1274,24 @@ netconf_module_load(clicon_handle h)
 	goto done;
     if (xml_parse_string("<CLICON_FEATURE>ietf-netconf:xpath</CLICON_FEATURE>", yspec, &xc) < 0)
 	goto done;
+    retval = 0;
+ done:
+    return retval;
+}
+
+/*! Load ietf netconf yang module and set enabled features
+ * @param[in] h  Clixon handle
+ * @retval    0  OK
+ * @retval   -1  Error
+ * @see netconf_module_feature  should be called before any yang modules
+ */
+int
+netconf_module_load(clicon_handle h)
+{
+    int        retval = -1;
+    yang_stmt *yspec;
+    
+    yspec = clicon_dbspec_yang(h);
     /* Load yang spec */
     if (yang_spec_parse_module(h, "ietf-netconf", NULL, yspec)< 0)
 	goto done;
diff --git a/lib/src/clixon_proto_client.c b/lib/src/clixon_proto_client.c
index 98ed0fdd..2cedc722 100644
--- a/lib/src/clixon_proto_client.c
+++ b/lib/src/clixon_proto_client.c
@@ -615,6 +615,85 @@ clicon_rpc_get(clicon_handle       h,
     return retval;
 }
 
+/*! Get database state data, clixon extension
+ * @param[in]  h         Clicon handle
+ * @param[in]  xpath     XPath in a filter stmt (or NULL/"" for no filter)
+ * @param[in]  namespace Namespace associated w xpath
+ * @param[out] xt        XML tree. Free with xml_free. 
+ *                       Either <config> or <rpc-error>. 
+ * @retval    0          OK
+ * @retval   -1          Error, fatal or xml
+ * @note if xpath is set but namespace is NULL, the default, netconf base 
+ *       namespace will be used which is most probably wrong.
+ * @code
+ *    cxobj *xt = NULL;
+ *    if (clicon_rpc_get_state(h, "/hello/world", "urn:example:hello", &xt) < 0)
+ *       err;
+ *   if ((xerr = xpath_first(xt, "/rpc-error")) != NULL){
+ *	clicon_rpc_generate_error(xerr);
+ *      err;
+ *  }
+ *    if (xt)
+ *       xml_free(xt);
+ * @endcode
+ * @see clicon_rpc_generate_error
+ */
+int
+clicon_rpc_get_state(clicon_handle       h, 
+		     char               *xpath,
+		     char               *namespace,
+		     cxobj             **xt)
+{
+    int                retval = -1;
+    struct clicon_msg *msg = NULL;
+    cbuf              *cb = NULL;
+    cxobj             *xret = NULL;
+    cxobj             *xd;
+    char              *username;
+
+    if ((cb = cbuf_new()) == NULL)
+	goto done;
+    cprintf(cb, "<rpc");
+    if ((username = clicon_username_get(h)) != NULL)
+	cprintf(cb, " username=\"%s\"", username);
+    if (namespace)
+	cprintf(cb, " xmlns:nc=\"%s\"", NETCONF_BASE_NAMESPACE);
+    cprintf(cb, "><cl:get-state xmlns:cl=\"http://clicon.org/lib\">");
+    if (xpath && strlen(xpath)) {
+	if (namespace)
+	    cprintf(cb, "<nc:filter nc:type=\"xpath\" nc:select=\"%s\" xmlns=\"%s\"/>",
+		    xpath, namespace);
+	else /* If xpath != /, this will probably yield an error later */
+	    cprintf(cb, "<filter type=\"xpath\" select=\"%s\"/>", xpath);
+    }
+    cprintf(cb, "</cl:get-state></rpc>");
+    if ((msg = clicon_msg_encode("%s", cbuf_get(cb))) == NULL)
+	goto done;
+    if (clicon_rpc_msg(h, msg, &xret, NULL) < 0)
+	goto done;
+    /* Send xml error back: first check error, then ok */
+    if ((xd = xpath_first(xret, "/rpc-reply/rpc-error")) != NULL)
+	xd = xml_parent(xd); /* point to rpc-reply */
+    else if ((xd = xpath_first(xret, "/rpc-reply/data")) == NULL)
+	if ((xd = xml_new("data", NULL, NULL)) == NULL)
+	    goto done;
+    if (xt){
+	if (xml_rm(xd) < 0)
+	    goto done;
+	*xt = xd;
+    }
+    retval = 0;
+  done:
+    if (cb)
+	cbuf_free(cb);
+    if (xret)
+	xml_free(xret);
+    if (msg)
+	free(msg);
+    return retval;
+}
+
+
 /*! Close a (user) session
  * @param[in] h        CLICON handle
  * @retval    0        OK
diff --git a/lib/src/clixon_xml_map.c b/lib/src/clixon_xml_map.c
index 83a9403a..6344245e 100644
--- a/lib/src/clixon_xml_map.c
+++ b/lib/src/clixon_xml_map.c
@@ -3196,7 +3196,7 @@ xml_merge(cxobj     *x0,
 	    goto done;
 	if (ymod == NULL){
 	    if (reason &&
-		(*reason = strdup("No namespace in XML tree found")) == NULL){
+		(*reason = strdup("Namespace not found or yang spec not loaded")) == NULL){
 		    clicon_err(OE_UNIX, errno, "strdup");
 		    goto done;
 	    }
diff --git a/test/test_restconf.sh b/test/test_restconf.sh
index 38ca60a6..6fa21d4c 100755
--- a/test/test_restconf.sh
+++ b/test/test_restconf.sh
@@ -74,12 +74,12 @@ expecteq "$(curl -s -H 'Accept: application/yang-data+xml' -G http://localhost/r
 
 # Should be alphabetically ordered
 new "restconf get restconf/operations. RFC8040 3.3.2 (json)"
-expecteq "$(curl -sG http://localhost/restconf/operations)" 0 '{"operations": {"clixon-example:client-rpc": null,"clixon-example:empty": null,"clixon-example:optional": null,"clixon-example:example": null,"clixon-lib:debug": null,"clixon-lib:ping": null,"ietf-netconf:get-config": null,"ietf-netconf:edit-config": null,"ietf-netconf:copy-config": null,"ietf-netconf:delete-config": null,"ietf-netconf:lock": null,"ietf-netconf:unlock": null,"ietf-netconf:get": null,"ietf-netconf:close-session": null,"ietf-netconf:kill-session": null,"ietf-netconf:commit": null,"ietf-netconf:discard-changes": null,"ietf-netconf:validate": null,"clixon-rfc5277:create-subscription": null}}
+expecteq "$(curl -sG http://localhost/restconf/operations)" 0 '{"operations": {"clixon-example:client-rpc": null,"clixon-example:empty": null,"clixon-example:optional": null,"clixon-example:example": null,"clixon-lib:debug": null,"clixon-lib:ping": null,"clixon-lib:get-state": null,"ietf-netconf:get-config": null,"ietf-netconf:edit-config": null,"ietf-netconf:copy-config": null,"ietf-netconf:delete-config": null,"ietf-netconf:lock": null,"ietf-netconf:unlock": null,"ietf-netconf:get": null,"ietf-netconf:close-session": null,"ietf-netconf:kill-session": null,"ietf-netconf:commit": null,"ietf-netconf:discard-changes": null,"ietf-netconf:validate": null,"clixon-rfc5277:create-subscription": null}}
 
'
 
 new "restconf get restconf/operations. RFC8040 3.3.2 (xml)"
 ret=$(curl -s -H "Accept: application/yang-data+xml" -G http://localhost/restconf/operations)
-expect='<operations><client-rpc xmlns="urn:example:clixon"/><empty xmlns="urn:example:clixon"/><optional xmlns="urn:example:clixon"/><example xmlns="urn:example:clixon"/><debug xmlns="http://clicon.org/lib"/><ping xmlns="http://clicon.org/lib"/><get-config xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"/><edit-config xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"/><copy-config xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"/><delete-config xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"/><lock xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"/><unlock xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"/><get xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"/><close-session xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"/><kill-session xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"/><commit xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"/><discard-changes xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"/><validate xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"/><create-subscription xmlns="urn:ietf:params:xml:ns:netmod:notification"/></operations>'
+expect='<operations><client-rpc xmlns="urn:example:clixon"/><empty xmlns="urn:example:clixon"/><optional xmlns="urn:example:clixon"/><example xmlns="urn:example:clixon"/><debug xmlns="http://clicon.org/lib"/><ping xmlns="http://clicon.org/lib"/><get-state xmlns="http://clicon.org/lib"/><get-config xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"/><edit-config xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"/><copy-config xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"/><delete-config xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"/><lock xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"/><unlock xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"/><get xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"/><close-session xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"/><kill-session xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"/><commit xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"/><discard-changes xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"/><validate xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"/><create-subscription xmlns="urn:ietf:params:xml:ns:netmod:notification"/></operations>'
 match=`echo $ret | grep -EZo "$expect"`
 if [ -z "$match" ]; then
     err "$expect" "$ret"
diff --git a/test/test_restconf_jukebox.sh b/test/test_restconf_jukebox.sh
index 411adf9c..3d5f2edf 100755
--- a/test/test_restconf_jukebox.sh
+++ b/test/test_restconf_jukebox.sh
@@ -8,6 +8,7 @@ APPNAME=example
 
 cfg=$dir/conf.xml
 fjukebox=$dir/example-jukebox.yang
+fcontent=$dir/example-events.yang
 
 # A "system" module as defined in B.2.4 
 cat <<EOF > $dir/example-system.yang
@@ -38,6 +39,25 @@ cat <<EOF > $cfg
 </clixon-config>
 EOF
 
+# yang B.3.1. "content" Parameter
+cat <<EOF > $fcontent
+   module example-events {
+      namespace "urn:example:events";
+      prefix "ex";
+     container events {
+       list event {
+         key name;
+         leaf name { type string; }
+         leaf description { type string; }
+         leaf event-count {
+           type uint32;
+           config false;
+         }
+       }
+     }
+}
+EOF
+
 # Common Jukebox spec (fjukebox must be set)
 . ./jukebox.sh
 
@@ -50,8 +70,8 @@ if [ $BE -ne 0 ]; then
 	err
     fi
     sudo pkill clixon_backend # to be sure
-    new "start backend -s init -f $cfg"
-    start_backend -s init -f $cfg
+    new "start backend -s init -f $cfg -- -s"
+    start_backend -s init -f "$cfg" -- -s
 fi
 
 new "kill old restconf daemon"
@@ -77,7 +97,7 @@ expectpart "$(curl -si -X GET -H 'Accept: application/yang-data+xml' http://loca
 # This just catches the header and the jukebox module, the RFC has foo and bar which
 # seems wrong to recreate
 new "B.1.2.  Retrieve the Server Module Information"
-expectpart "$(curl -si -X GET -H 'Accept: application/yang-data+json' http://localhost/restconf/data/ietf-yang-library:modules-state)" 0 "HTTP/1.1 200 OK" 'Cache-Control: no-cache' "Content-Type: application/yang-data+json" '{"ietf-yang-library:modules-state":{"module-set-id":' '"module":\[{"name":"example-jukebox","revision":"2016-08-15","namespace":"http://example.com/ns/example-jukebox","conformance-type":"implement"}'
+expectpart "$(curl -si -X GET -H 'Accept: application/yang-data+json' http://localhost/restconf/data/ietf-yang-library:modules-state)" 0 "HTTP/1.1 200 OK" 'Cache-Control: no-cache' "Content-Type: application/yang-data+json" '{"ietf-yang-library:modules-state":{"module-set-id":' '"module":\[{"name":"example-events","revision":\[null\],"namespace":"urn:example:events","conformance-type":"implement"},{"name":"example-jukebox","revision":"2016-08-15","namespace":"http://example.com/ns/example-jukebox","conformance-type":"implement"}'
 
 new "B.1.3.  Retrieve the Server Capability Information"
 expectpart "$(curl -si -X GET -H 'Accept: application/yang-data+xml' http://localhost/restconf/data/ietf-restconf-monitoring:restconf-state/capabilities)" 0 "HTTP/1.1 200 OK" "Content-Type: application/yang-data+xml" 'Cache-Control: no-cache' '<capabilities xmlns="urn:ietf:params:xml:ns:yang:ietf-restconf-monitoring"><capability>urn:ietf:params:restconf:capability:defaults:1.0?basic-mode=explicit</capability></capabilities>'
@@ -129,6 +149,22 @@ expectpart "$(curl -si -X PATCH http://localhost/restconf/data/example-jukebox:j
 new "B.2.5.  Check edit"
 expectpart "$(curl -si -X GET http://localhost/restconf/data/example-jukebox:jukebox/library/artist=Nick%20Cave%20and%20the%20Bad%20Seeds -H 'Accept: application/yang-data+xml')" 0 'HTTP/1.1 200 OK' '<artist xmlns="http://example.com/ns/example-jukebox"><name>Nick Cave and the Bad Seeds</name><album><name>Tender Prey</name><year>1988</year></album><album><name>The Good Son</name><year>1990</year></album></artist>'
 
+# note reverse order of down/up as it is ordered by system and down is before up
+new 'B.3.1.  "content" Parameter (preamble, add content)'
+expectpart "$(curl -si -X PUT -H 'Content-Type: application/yang-data+json' http://localhost/restconf/data/example-events:events -d '{"example-events:events":{"event":[{"name":"interface-down","description":"Interface down notification count"},{"name":"interface-up","description":"Interface up notification count"}]}}')" 0 "HTTP/1.1 201 Created"
+
+new 'B.3.1.  "content" Parameter (wrong content)'
+expectpart "$(curl -si -X GET http://localhost/restconf/data/example-events:events?content=kalle -H 'Accept: application/yang-data+json')" 0 'HTTP/1.1 400 Bad Request' '{"ietf-restconf:errors":{"error":{"error-type":"application","error-tag":"bad-attribute","error-info":{"bad-attribute":"content"},"error-severity":"error","error-message":"Unrecognized value of content attribute"}}}'
+
+new 'B.3.1.  "content" Parameter example 1: content=all'
+expectpart "$(curl -si -X GET http://localhost/restconf/data/example-events:events?content=all -H 'Accept: application/yang-data+json')" 0 'HTTP/1.1 200 OK' '{"example-events:events":{"event":\[{"name":"interface-down","description":"Interface down notification count","event-count":90},{"name":"interface-up","description":"Interface up notification count","event-count":77}\]}}'
+
+new 'B.3.1.  "content" Parameter example 2: content=config'
+expectpart "$(curl -si -X GET http://localhost/restconf/data/example-events:events?content=config -H 'Accept: application/yang-data+json')" 0 'HTTP/1.1 200 OK' '{"example-events:events":{"event":\[{"name":"interface-down","description":"Interface down notification count"},{"name":"interface-up","description":"Interface up notification count"}\]}}'
+
+new 'B.3.1.  "content" Parameter example 3: content=nonconfig'
+expectpart "$(curl -si -X GET http://localhost/restconf/data/example-events:events?content=nonconfig -H 'Accept: application/yang-data+json')" 0 'HTTP/1.1 200 OK' '{"example-events:events":{"event":\[{"name":"interface-down","event-count":90},{"name":"interface-up","event-count":77}\]}}'
+
 new "restconf DELETE whole datastore"
 expectfn 'curl -s -X DELETE http://localhost/restconf/data' 0 ""
 
@@ -188,7 +224,6 @@ expectpart "$(curl -si -X GET http://localhost/restconf/data/example-jukebox:ext
 if false; then # NYI
 
 new "B.2.2.  Detect Datastore Resource Entity-Tag Change" # XXX done except entity-changed
-new 'B.3.1.  "content" Parameter'
 new 'B.3.2.  "depth" Parameter'
 new 'B.3.3.  "fields" Parameter'
 new 'B.3.6.  "filter" Parameter'
diff --git a/test/test_yang.sh b/test/test_yang.sh
index b962201a..3c1891ee 100755
--- a/test/test_yang.sh
+++ b/test/test_yang.sh
@@ -2,7 +2,7 @@
 # Yang test: multi-keys and empty type
 
 # Magic line must be first in script (see README.md)
-s="$_" ; . ./lib.sh || if [ "$s" = $0 ]; then exit 0; else return 0; fi
+s="$_" ; . ./lib.sh || if [ "$s" = "$0" ]; then exit 0; else return 0; fi
 
 APPNAME=example
 
@@ -143,14 +143,14 @@ EOF
 
 new "test params: -f $cfg"
 
-if [ $BE -ne 0 ]; then
+if [ "$BE" -ne 0 ]; then
     new "kill old backend"
-    sudo clixon_backend -zf $cfg
+    sudo clixon_backend -zf "$cfg"
     if [ $? -ne 0 ]; then
 	err
     fi
     new "start backend -s init -f $cfg"
-    start_backend -s init -f $cfg
+    start_backend -s init -f "$cfg"
 
     new "waiting"
     wait_backend
@@ -280,18 +280,18 @@ expecteof "$clixon_netconf -qf $cfg" 0 "<rpc><validate><source><candidate/></sou
 new "netconf submodule discard-changes"
 expecteof "$clixon_netconf -qf $cfg" 0 "<rpc><discard-changes/></rpc>]]>]]>" "^<rpc-reply><ok/></rpc-reply>]]>]]>$"
 
-if [ $BE -eq 0 ]; then
+if [ "$BE" -eq 0 ]; then
     exit # BE
 fi
 
 new "Kill backend"
 # Check if premature kill
-pid=`pgrep -u root -f clixon_backend`
+pid=$(pgrep -u root -f clixon_backend)
 if [ -z "$pid" ]; then
     err "backend already dead"
 fi
 # kill backend
-stop_backend -f $cfg
+stop_backend -f "$cfg"
 sudo pkill -u root -f clixon_backend
 
-rm -rf $dir
+rm -rf "$dir"
diff --git a/yang/clixon/Makefile.in b/yang/clixon/Makefile.in
index c982ddc2..87d5e65b 100644
--- a/yang/clixon/Makefile.in
+++ b/yang/clixon/Makefile.in
@@ -42,7 +42,7 @@ datarootdir     = @datarootdir@
 YANG_INSTALLDIR   = @YANG_INSTALLDIR@
 
 YANGSPECS	 = clixon-config@2019-06-05.yang
-YANGSPECS	+= clixon-lib@2019-06-05.yang
+YANGSPECS	+= clixon-lib@2019-08-13.yang
 YANGSPECS	+= clixon-rfc5277@2008-07-01.yang
 YANGSPECS	+= clixon-xml-changelog@2019-03-21.yang
 
diff --git a/yang/clixon/clixon-lib@2019-06-05.yang b/yang/clixon/clixon-lib@2019-08-13.yang
similarity index 67%
rename from yang/clixon/clixon-lib@2019-06-05.yang
rename to yang/clixon/clixon-lib@2019-08-13.yang
index 370819c8..343ca634 100644
--- a/yang/clixon/clixon-lib@2019-06-05.yang
+++ b/yang/clixon/clixon-lib@2019-08-13.yang
@@ -40,6 +40,10 @@ module clixon-lib {
 
        ***** END LICENSE BLOCK *****";
 
+    revision 2019-08-13 {
+	description
+	    "get-state added for restconf content=nonconfig internal rpc";
+    }
     revision 2019-06-05 {
 	description
 	    "ping rpc added for liveness";
@@ -59,4 +63,34 @@ module clixon-lib {
     rpc ping {
         description "Check aliveness of backend daemon.";
     }
+    rpc get-state {
+      description
+        "Retrieve device state information only. This is a clixon extension
+         to ietf-netconf to implement RESTCONF GET with attribute 
+         content=nonconfig. 
+         The reason is that netconf only has <get> and <get-config> neither
+         which retrieves state only";
+
+      reference "RFC 8040 4.8.1";
+
+      input {
+        anyxml filter {
+          description
+            "This parameter specifies the portion of the system
+             configuration and state data to retrieve.";
+          nc:get-filter-element-attributes;
+        }
+      }
+
+      output {
+        anyxml data {
+          description
+            "Copy of the running datastore subset and/or state
+             data that matched the filter criteria (if any).
+             An empty data container indicates that the request did not
+             produce any results.";
+        }
+      }
+    }
+
 }