* YANG schema mount RFC 8528, Initial commit (work in progress)

* Keep track of YANG unknowns with ys_cvec of EXTENSION
* C-API: Init ys_cvec to NULL, added yang_cvec_add() and adjusted code to use it

CHANGELOG.md

@@ -43,7 +43,12 @@ Expected: beginning of 2023
 
 ### New features
 
-* Netconf monitoring, part 2
+* YANG schema mount RFC 8528 (work in progress)
+  * Restrictions:
+    * only schema-ref=inline, not shared-schema
+  * Standards: RFC 8528
+  * Enable `YANG_SCHEMA_MOUNT`
+* Netconf monitoring RFC 6022 , part 2
   * Datastores and sessions
     * Added clixon-specific transport identities: cli, snmp, netconf, restconf
     * Added source-host fro native restonf, but no other transports

apps/backend/backend_get.c

@@ -297,6 +297,19 @@ get_client_statedata(clicon_handle     h,
         if (ret == 0)
             goto fail;
     }
+#ifdef YANG_SCHEMA_MOUNT
+    if ((ret = schema_mounts_state_get(h, yspec, xpath, nsc, xret, &xerr)) < 0)
+        goto done;
+    if (ret == 0){
+        if (clixon_netconf_internal_error(xerr, " . Internal error, schema_mounts_state_get returned invalid XML", NULL) < 0)
+            goto done;
+        if (*xret)
+            xml_free(*xret);
+        *xret = xerr;
+        xerr = NULL;
+        goto fail;
+    }
+#endif
     /* Use plugin state callbacks */
     if ((ret = clixon_plugin_statedata_all(h, yspec, nsc, xpath, wdef, xret)) < 0)
         goto done;

apps/cli/cli_show.c

@@ -266,12 +266,6 @@ expand_dbvar(void   *h,
     /* Transform api-path to xpath for netconf */
     if (api_path2xpath(api_path, yspec, &xpath, &nsc, NULL) < 0)
         goto done;
-    if (nsc != NULL){
-        cvec_free(nsc);
-        nsc = NULL;
-    }
-    if (xml_nsctx_yang(y, &nsc) < 0)
-        goto done;
     if ((cbxpath = cbuf_new()) == NULL){
         clicon_err(OE_UNIX, errno, "cbuf_new");
         goto done;

apps/restconf/restconf_methods.c

@@ -143,7 +143,8 @@ match_list_keys(yang_stmt *y,
     clicon_debug(1, "%s", __FUNCTION__);
     switch (yang_keyword_get(y)){
     case Y_LIST:
-        cvk = yang_cvec_get(y); /* Use Y_LIST cache, see ys_populate_list() */
+        if ((cvk = yang_cvec_get(y)) == NULL) /* Use Y_LIST cache, see ys_populate_list() */
+            break;
         cvi = NULL;
         while ((cvi = cvec_each(cvk, cvi)) != NULL) {
             keyname = cv_string_get(cvi);           

apps/snmp/snmp_lib.c

@@ -900,7 +900,8 @@ snmp_yang2xpath_cb(yang_stmt *ys,
     }
     switch (yang_keyword_get(ys)){
     case Y_LIST:
-        cvk = yang_cvec_get(ys); /* Use Y_LIST cache, see ys_populate_list() */
+        if ((cvk = yang_cvec_get(ys)) == NULL) /* Use Y_LIST cache, see ys_populate_list() */
+            break;
         /* Iterate over individual keys  */
         assert(keyvec && cvec_len(cvk) == cvec_len(keyvec));
         for (i=0; i<cvec_len(cvk); i++){

include/clixon_custom.h

@@ -191,3 +191,9 @@
  * To keep the previous behavior (as in 6.0) set this option with #define
  */
 #undef NETCONF_DEFAULT_RETRIEVAL_REPORT_ALL
+
+/*! Development option for RFC 8528 YANG schema mount
+ * Work-in-progress
+ * See also test/test_yang_schema_mount.sh
+ */
+#undef YANG_SCHEMA_MOUNT

lib/clixon/clixon.h.in

@@ -84,6 +84,7 @@ extern "C" {
 #include <clixon/clixon_xml_sort.h>
 #include <clixon/clixon_yang_parse_lib.h>
 #include <clixon/clixon_yang_module.h>
+#include <clixon/clixon_yang_schema_mount.h>
 #include <clixon/clixon_netconf_monitoring.h>
 #include <clixon/clixon_stream.h>
 #include <clixon/clixon_proto.h>

lib/clixon/clixon_plugin.h

@@ -132,8 +132,8 @@ typedef int (plgdaemon_t)(clicon_handle);              /* Plugin pre/post daemon
  */
 typedef int (plgexit_t)(clicon_handle);                /* Plugin exit */
 
-/* For yang extension handling. 
+/* For yang extension/unknown handling. 
- * Called at parsing of yang module containing a statement of an extension.
+ * Called at parsing of yang module containing an unknown statement of an extension.
  * A plugin may identify the extension by its name, and perform actions
  * on the yang statement, such as transforming the yang.
  * A callback is made for every statement, which means that several calls per
@@ -294,7 +294,7 @@ struct clixon_plugin_api{
     plginit2_t       *ca_init;           /* Clixon plugin Init (implicit) */
     plgstart_t       *ca_start;          /* Plugin start */
     plgexit_t        *ca_exit;           /* Plugin exit */
-    plgextension_t   *ca_extension;      /* Yang extension handler */
+    plgextension_t   *ca_extension;      /* Yang extension/unknown handler */
     union {
         struct { /* cli-specific */
             cli_prompthook_t *ci_prompt;         /* Prompt hook */

lib/clixon/clixon_xml.h

@@ -165,6 +165,9 @@ typedef enum yang_bind yang_bind;
 typedef struct xml cxobj; /* struct defined in clicon_xml.c */
 
 /*! Callback function type for xml_apply 
+ *
+ * @param[in]  x    XML node  
+ * @param[in]  arg  General-purpose argument
  * @retval    -1    Error, aborted at first error encounter, return -1 to end user
  * @retval     0    OK, continue
  * @retval     1    Abort, dont continue with others, return 1 to end user

lib/clixon/clixon_yang_module.h

@@ -66,7 +66,7 @@ int modstate_diff_free(modstate_diff_t *);
 
 int yang_modules_init(clicon_handle h);
 char *yang_modules_revision(clicon_handle h);
-
+int yang_modules_state_build(clicon_handle h, yang_stmt *yspec, char *msid, int brief, cbuf *cb);
 int yang_modules_state_get(clicon_handle h, yang_stmt *yspec, char *xpath,
                            cvec *nsc, int brief, cxobj **xret);
 int clixon_module_upgrade(clicon_handle h, cxobj *xt, modstate_diff_t *msd, cbuf *cb);

lib/clixon/clixon_yang_schema_mount.h

@@ -0,0 +1,55 @@
+/*
+ *
+  ***** BEGIN LICENSE BLOCK *****
+ 
+  Copyright (C) 2023 Olof Hagsand
+
+  This file is part of CLIXON.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+  Alternatively, the contents of this file may be used under the terms of
+  the GNU General Public License Version 3 or later (the "GPL"),
+  in which case the provisions of the GPL are applicable instead
+  of those above. If you wish to allow use of your version of this file only
+  under the terms of the GPL, and not to allow others to
+  use your version of this file under the terms of Apache License version 2, 
+  indicate your decision by deleting the provisions above and replace them with
+  the  notice and other provisions required by the GPL. If you do not delete
+  the provisions above, a recipient may use your version of this file under
+  the terms of any one of the Apache License version 2 or the GPL.
+
+  ***** END LICENSE BLOCK *****
+
+ */
+
+#ifndef _CLIXON_YANG_SCHEMA_MOUNT_H_
+#define _CLIXON_YANG_SCHEMA_MOUNT_H_
+
+/*
+ * Constants
+ */
+
+/* RFC 8528 YANG Schema Mount
+ */
+#define YANG_SCHEMA_MOUNT_NAMESPACE "urn:ietf:params:xml:ns:yang:ietf-yang-schema-mount"
+
+/*
+ * Prototypes
+ */
+int yang_schema_mount_point(yang_stmt *y);
+
+int schema_mounts_state_get(clicon_handle h, yang_stmt *yspec, char *xpath, cvec *nsc, cxobj **xret, cxobj **xerr);
+int yang_schema_unknown(clicon_handle h, yang_stmt *yext, yang_stmt *ys);
+
+#endif  /* _CLIXON_YANG_SCHEMA_MOUNT_H_ */

lib/src/Makefile.in

@@ -84,7 +84,8 @@ SRC     = clixon_sig.c clixon_uid.c clixon_log.c clixon_err.c clixon_event.c \
 	  clixon_xml_default.c clixon_xml_bind.c clixon_json.c clixon_proc.c \
 	  clixon_yang.c clixon_yang_type.c clixon_yang_module.c clixon_netconf_monitoring.c \
 	  clixon_yang_parse_lib.c clixon_yang_sub_parse.c \
-          clixon_yang_cardinality.c clixon_xml_changelog.c clixon_xml_nsctx.c \
+          clixon_yang_cardinality.c clixon_yang_schema_mount.c \
+          clixon_xml_changelog.c clixon_xml_nsctx.c \
 	  clixon_path.c clixon_validate.c clixon_validate_minmax.c \
 	  clixon_hash.c clixon_options.c clixon_data.c clixon_plugin.c \
 	  clixon_proto.c clixon_proto_client.c \

lib/src/clixon_datastore_write.c

@@ -527,6 +527,7 @@ text_modify(clicon_handle       h,
         }
     }
     x1name = xml_name(x1);
+
     if (yang_keyword_get(y0) == Y_LEAF_LIST ||
         yang_keyword_get(y0) == Y_LEAF){
         /* This is a check that a leaf does not have sub-elements 
@@ -897,6 +898,7 @@ text_modify(clicon_handle       h,
             while ((x1c = xml_child_each(x1, x1c, CX_ELMNT)) != NULL) {
                 x0c = x0vec[i++];
                 x1cname = xml_name(x1c);
+
                 yc = yang_find_datanode(y0, x1cname);
                 if ((ret = text_modify(h, x0c, x0, x0t, x1c, x1t,
                                        yc, op,
@@ -963,10 +965,8 @@ text_modify(clicon_handle       h,
 
 /*! Modify a top-level base tree x0 with modification tree x1
  * @param[in]  h        Clicon handle
- * @param[in]  x0       Base xml tree (can be NULL in add scenarios)
+ * @param[in]  x0t      Base xml tree (can be NULL in add scenarios)
- * @param[in]  x0t      Top level of existing tree, eg needed for NACM rules
+ * @param[in]  x1t       XML tree which modifies base
- * @param[in]  x1       XML tree which modifies base
- * @param[in]  x1t      Request root node (nacm needs this)
  * @param[in]  yspec    Top-level yang spec (if y is NULL)
  * @param[in]  op       OP_MERGE, OP_REPLACE, OP_REMOVE, etc 
  * @param[in]  username User name of requestor for nacm
@@ -980,9 +980,7 @@ text_modify(clicon_handle       h,
  */
 static int
 text_modify_top(clicon_handle       h,
-                cxobj              *x0,
                 cxobj              *x0t,
-                cxobj              *x1,
                 cxobj              *x1t,
                 yang_stmt          *yspec,
                 enum operation_type op,
@@ -1002,7 +1000,7 @@ text_modify_top(clicon_handle       h,
     char      *createstr = NULL;
     
     /* Check for operations embedded in tree according to netconf */
-    if ((ret = attr_ns_value(x1,
+    if ((ret = attr_ns_value(x1t,
                              "operation", NETCONF_BASE_NAMESPACE,
                              cbret, &opstr)) < 0)
         goto done;
@@ -1011,25 +1009,25 @@ text_modify_top(clicon_handle       h,
     if (opstr != NULL)
         if (xml_operation(opstr, &op) < 0)
             goto done;
-    if ((ret = attr_ns_value(x1, "objectcreate", NULL, cbret, &createstr)) < 0)
+    if ((ret = attr_ns_value(x1t, "objectcreate", NULL, cbret, &createstr)) < 0)
         goto done;
     if (ret == 0)
         goto fail;
-    /* Special case if incoming x1 is empty, top-level only <config/> */
+    /* Special case if incoming x1t is empty, top-level only <config/> */
-    if (xml_child_nr_type(x1, CX_ELMNT) == 0){ 
+    if (xml_child_nr_type(x1t, CX_ELMNT) == 0){ 
-        if (xml_child_nr_type(x0, CX_ELMNT)){ /* base tree not empty */
+        if (xml_child_nr_type(x0t, CX_ELMNT)){ /* base tree not empty */
             switch(op){ 
             case OP_DELETE:
             case OP_REMOVE:
             case OP_REPLACE:
                 if (!permit && xnacm){
-                    if ((ret = nacm_datanode_write(h, x0, x0t, NACM_DELETE, username, xnacm, cbret)) < 0)
+                    if ((ret = nacm_datanode_write(h, x0t, x0t, NACM_DELETE, username, xnacm, cbret)) < 0)
                         goto done;
                     if (ret == 0)
                         goto fail;
                     permit = 1;
                 }
-                while ((x0c = xml_child_i(x0, 0)) != 0)
+                while ((x0c = xml_child_i(x0t, 0)) != 0)
                     if (xml_purge(x0c) < 0)
                         goto done;
                 break;
@@ -1057,25 +1055,25 @@ text_modify_top(clicon_handle       h,
     /* Special case top-level replace */
     else if (op == OP_REPLACE || op == OP_DELETE){
         if (createstr != NULL){
-            if (xml_child_nr_type(x0, CX_ELMNT)) /* base tree not empty */
+            if (xml_child_nr_type(x0t, CX_ELMNT)) /* base tree not empty */
                 clicon_data_set(h, "objectexisted", "true");
             else
                 clicon_data_set(h, "objectexisted", "false");
         }
         if (!permit && xnacm){
-            if ((ret = nacm_datanode_write(h, x1, x1t, NACM_UPDATE, username, xnacm, cbret)) < 0) 
+            if ((ret = nacm_datanode_write(h, x1t, x1t, NACM_UPDATE, username, xnacm, cbret)) < 0) 
                 goto done;
             if (ret == 0)
                 goto fail;
             permit = 1;
         }
-        while ((x0c = xml_child_i(x0, 0)) != 0)
+        while ((x0c = xml_child_i(x0t, 0)) != 0)
             if (xml_purge(x0c) < 0)
                 goto done;
     }
     /* Loop through children of the modification tree */
     x1c = NULL;
-    while ((x1c = xml_child_each(x1, x1c, CX_ELMNT)) != NULL) {
+    while ((x1c = xml_child_each(x1t, x1c, CX_ELMNT)) != NULL) {
         x1cname = xml_name(x1c);
         /* Get yang spec of the child */
         yc = NULL;
@@ -1101,7 +1099,7 @@ text_modify_top(clicon_handle       h,
             }
         }
         /* See if there is a corresponding node in the base tree */
-        if (match_base_child(x0, x1c, yc, &x0c) < 0)
+        if (match_base_child(x0t, x1c, yc, &x0c) < 0)
             goto done;
         if (x0c && (yc != xml_spec(x0c))){
             /* There is a match but is should be replaced (choice)*/
@@ -1109,7 +1107,7 @@ text_modify_top(clicon_handle       h,
                 goto done;
             x0c = NULL;
         }
-        if ((ret = text_modify(h, x0c, x0, x0t, x1c, x1t,
+        if ((ret = text_modify(h, x0c, x0t, x0t, x1c, x1t,
                                yc, op,
                                username, xnacm, permit, cbret)) < 0)
             goto done;
@@ -1228,7 +1226,7 @@ xmldb_put(clicon_handle       h,
      * Modify base tree x with modification x1. This is where the
      * new tree is made.
      */
-    if ((ret = text_modify_top(h, x0, x0, x1, x1, yspec, op, username, xnacm, permit, cbret)) < 0)
+    if ((ret = text_modify_top(h, x0, x1, yspec, op, username, xnacm, permit, cbret)) < 0)
         goto done;
     /* If xml return - ie netconf error xml tree, then stop and return OK */
     if (ret == 0){

lib/src/clixon_path.c

@@ -1344,6 +1344,7 @@ api_path_resolve(clixon_path *cplist,
     int          i;
     cg_var      *cva;
     cg_var      *cvy;
+    cvec        *cvk;
     
     if ((cp = cplist) != NULL){
         do {
@@ -1372,7 +1373,8 @@ api_path_resolve(clixon_path *cplist,
                     }
                 }
                 else if (yang_keyword_get(yc) == Y_LIST){
-                    if (cvec_len(cp->cp_cvk) > cvec_len(yang_cvec_get(yc))){
+                    cvk = yang_cvec_get(yc);
+                    if (cvec_len(cp->cp_cvk) > cvec_len(cvk)){
                         clicon_err(OE_YANG, ENOENT, "Number of keys in key-value list does not match Yang list");
                         goto fail;
                     }
@@ -1384,7 +1386,7 @@ api_path_resolve(clixon_path *cplist,
                                        cv_name_get(cva));
                             goto fail;
                         }
-                        cvy = cvec_i(yang_cvec_get(yc), i++);
+                        cvy = cvec_i(cvk, i++);
                         cv_name_set(cva, cv_string_get(cvy));
                     }
                 }

lib/src/clixon_validate_minmax.c

@@ -227,7 +227,6 @@ check_unique_list_direct(cxobj     *x,
     char      *str;
     cvec      *cvk;
 
-    cvk = yang_cvec_get(yu);
     /* If list and is sorted by system, then it is assumed elements are in key-order which is optimized
      * Other cases are "unique" constraint or list sorted by user which is quadratic in complexity
      * This second case COULD be optimized if binary insert is made on the vec vector.

lib/src/clixon_xml_bind.c

@@ -137,8 +137,8 @@ strip_body_objects(cxobj *xt)
  *
  * @param[in]   xt     XML tree node
  * @param[out]  xerr   Reason for failure, or NULL
- * @retval      1      OK Yang assignment made
  * @retval      2      OK Yang assignment not made because yang parent is anyxml or anydata
+ * @retval      1      OK Yang assignment made
  * @retval      0      Yang assigment not made and xerr set
  * @retval     -1      Error
  * @note retval = 2 is special

lib/src/clixon_xml_default.c

@@ -178,7 +178,7 @@ xml_default_choice(yang_stmt *yc,
     yang_stmt *yca = NULL;
     yang_stmt *ydef;
 
-    clicon_debug(1, "%s", __FUNCTION__);
+    clicon_debug(2, "%s", __FUNCTION__);
     /* 1. Is there a default case and no child under this choice?
      */
     x = NULL;

lib/src/clixon_yang.c

@@ -84,6 +84,7 @@
 #include "clixon_yang_parse_lib.h"
 #include "clixon_yang_cardinality.h"
 #include "clixon_yang_type.h"
+#include "clixon_yang_schema_mount.h"
 #include "clixon_yang_internal.h" /* internal included by this file only, not API*/
 
 #ifdef XML_EXPLICIT_INDEX
@@ -274,6 +275,7 @@ yang_cv_set(yang_stmt *ys,
 
 /*! Get yang statement CLIgen variable vector
  * @param[in] ys  Yang statement node
+ * @note  To add entries, use yang_cvec_add(), since this function may return NULL
  */
 cvec*
 yang_cvec_get(yang_stmt *ys)
@@ -297,6 +299,41 @@ yang_cvec_set(yang_stmt *ys,
     return 0;
 }
 
+/*! Add new value to yang cvec, create if not exist
+ *
+ * @param[in] ys    Yang statement
+ * @param[in] type  Append a new cv to the vector with this type
+ * @param[in] name  Name of variable
+ * @retval    cv    The new cligen variable
+ * @retval    NULL  Error
+ */
+static cg_var *
+yang_cvec_add(yang_stmt    *ys,
+              enum cv_type type,
+              char        *name)
+              
+{
+    cg_var *cv;
+    cvec   *cvv;
+
+    if ((cvv = yang_cvec_get(ys)) == NULL){
+        if ((cvv = cvec_new(0)) == NULL){ 
+            clicon_err(OE_YANG, errno, "cvec_new");
+            return NULL;
+        }
+        yang_cvec_set(ys, cvv);
+    }
+    if ((cv = cvec_add(cvv, type)) == NULL){
+        clicon_err(OE_YANG, errno, "cvec_add");
+        return NULL;
+    }
+    if (cv_name_set(cv, name) == NULL){
+        clicon_err(OE_YANG, errno, "cv_name_set(%s)", name);
+        return NULL;
+    }
+    return cv;
+}
+
 /*! Get yang stmt flags, used for internal algorithms
  * @param[in]  ys     Yang statement
  * @param[in]  flag   Flags value(s) to get, see YANG_FLAG_*
@@ -594,7 +631,6 @@ yang_stmt *
 ys_new(enum rfc_6020 keyw)
 {
     yang_stmt *ys;
-    cvec      *cvv;
 
     if ((ys = malloc(sizeof(*ys))) == NULL){
         clicon_err(OE_YANG, errno, "malloc");
@@ -602,13 +638,6 @@ ys_new(enum rfc_6020 keyw)
     }
     memset(ys, 0, sizeof(*ys));
     ys->ys_keyword    = keyw;
-    /* The cvec contains stmt-specific variables. Only few stmts need variables so the
-       cvec could be lazily created to save some heap and cycles. */
-    if ((cvv = cvec_new(0)) == NULL){ 
-        clicon_err(OE_YANG, errno, "cvec_new");
-        return NULL;
-    }
-    yang_cvec_set(ys, cvv);
     _stats_yang_nr++;
     return ys;
 }
@@ -1082,13 +1111,17 @@ yang_match(yang_stmt *yn,
     return match;
 }
 
+
 /*! Find child data node with matching argument (container, leaf, list, leaf-list)
  *
  * @param[in]  yn         Yang node, current context node.
- * @param[in]  argument   if NULL, match any(first) argument. XXX is that really a case?
+ * @param[in]  argument   Argument that child should match with
+ * @retval     ymatch     Matching child
+ * @retval     NULL       No match or error
  *
  * @see yang_find   Looks for any node
  * @note May deviate from RFC since it explores choice/case not just return it.
+ * XXX: differentiate between not found and error
  */
 yang_stmt *
 yang_find_datanode(yang_stmt *yn, 
@@ -1099,7 +1132,16 @@ yang_find_datanode(yang_stmt *yn,
     yang_stmt *yspec;
     yang_stmt *ysmatch = NULL;
     char      *name;
+#ifdef YANG_SCHEMA_MOUNT
+    int ret;
     
+    /* Sanity-check mount-point extension */
+    if ((ret = yang_schema_mount_point(yn)) < 0)
+        goto done;
+    if (ret == 1){
+        ; // NYI
+    }
+#endif
     ys = NULL;
     while ((ys = yn_each(yn, ys)) != NULL){
         if (yang_keyword_get(ys) == Y_CHOICE){ /* Look for its children */
@@ -1109,14 +1151,11 @@ yang_find_datanode(yang_stmt *yn,
                     ysmatch = yang_find_datanode(yc, argument);
                 else
                     if (yang_datanode(yc)){
-                        if (argument == NULL)
-                            ysmatch = yc;
-                        else
                         if (yc->ys_argument && strcmp(argument, yc->ys_argument) == 0)
                             ysmatch = yc;
                     }
                 if (ysmatch)
-                    goto match; // maybe break?
+                    goto done; // maybe break?
             }
         } /* Y_CHOICE */
         else if (yang_keyword_get(ys) == Y_INPUT ||
@@ -1131,7 +1170,7 @@ yang_find_datanode(yang_stmt *yn,
                 if (ys->ys_argument && strcmp(argument, ys->ys_argument) == 0)
                     ysmatch = ys;
             if (ysmatch)
-                goto match; // maybe break?
+                goto done; // maybe break?
         }
     }
     /* Special case: if not match and yang node is module or submodule, extend
@@ -1150,7 +1189,7 @@ yang_find_datanode(yang_stmt *yn,
             }
         }
     }
- match:
+ done:
     return ysmatch;
 }
 
@@ -2265,14 +2304,12 @@ bound_add(yang_stmt   *ys,
     char   *reason = NULL;
     int     ret = 1;
 
-    if ((cv = cvec_add(ys->ys_cvec, cvtype)) == NULL){
+    if (ys == NULL){
-        clicon_err(OE_YANG, errno, "cvec_add");
+        clicon_err(OE_YANG, EINVAL, "ys is NULL");
         goto done;
     }
-    if (cv_name_set(cv, name) == NULL){
+    if ((cv = yang_cvec_add(ys, cvtype, name)) == NULL)
-        clicon_err(OE_YANG, errno, "cv_name_set(%s)", name);
         goto done;
-    }
     if (cvtype == CGV_DEC64)
         cv_dec64_n_set(cv, fraction_digits);
     if (strcmp(val, "min") == 0)
@@ -2480,7 +2517,6 @@ ys_populate_identity(clicon_handle h,
     int             retval = -1;
     yang_stmt      *yc = NULL;
     yang_stmt      *ybaseid;
-    cg_var         *cv;
     char           *baseid;
     char           *prefix = NULL;
     char           *id = NULL;
@@ -2526,17 +2562,10 @@ ys_populate_identity(clicon_handle h,
         if (cvec_find(idrefvec, idref) != NULL)
             continue;
         /* Add derived id to ybaseid */
-        if ((cv = cv_new(CGV_STRING)) == NULL){
+        if (yang_cvec_add(ybaseid, CGV_STRING, idref) == NULL){
             clicon_err(OE_UNIX, errno, "cv_new"); 
             goto done;
         }
-        /* add prefix */
-        cv_name_set(cv, idref);
-        cvec_append_var(idrefvec, cv); /* cv copied */
-        if (cv){
-            cv_free(cv);
-            cv = NULL;
-        }
         /* Transitive to the root */
         if (ys_populate_identity(h, ybaseid, idref) < 0)
             goto done;
@@ -2662,11 +2691,20 @@ ys_populate_unique(clicon_handle h,
 }
 
 /*! Populate unknown node with extension
+ *
  * @param[in] h    Clicon handle
  * @param[in] ys   The yang statement (unknown) to populate.
+ * @retval    0    OK
+ * @retval   -1    Error
  * RFC 7950 Sec 7.19:
  * If no "argument" statement is present, the keyword expects no argument when
  * it is used.
+ * A pointer to the unknwon node is stored in the cvec of the extension:
+ *                     1              n
+ *   yang-extension ext1 (cvec) --->  unknown of ext1
+ *          (yext)               (ys)
+ *
+ * @note this breaks if yangs are freed
  * Note there is some complexity in different yang modules with unknown-statements.
  * y0) The location of the extension definition. E.g. extension autocli-op
  * y1) The location of the unknown-statement (ys). This is for example: cl:autocli-op hide.
@@ -2717,6 +2755,10 @@ ys_populate_unknown(clicon_handle h,
         clicon_debug(1, "plugin_extension() failed");
         return -1;
     }
+#endif
+#ifdef YANG_SCHEMA_MOUNT
+    if (yang_schema_unknown(h, yext, ys) < 0)
+        goto done;
 #endif
     /* Make extension callbacks that may alter yang structure 
      * Note: this may be a "layering" violation: assuming plugins are loaded
@@ -2724,6 +2766,12 @@ ys_populate_unknown(clicon_handle h,
      */
     if (clixon_plugin_extension_all(h, yext, ys) < 0)
         goto done;
+#if 1
+    /* Add unknown to vector in extension */
+    if ((cv = yang_cvec_add(yext, CGV_VOID, yang_argument_get(ys))) == NULL)
+        goto done;
+    cv_void_set(cv, ys);
+#endif
     retval = 0;
  done:
     if (prefix)

lib/src/clixon_yang_internal.h

@@ -95,6 +95,7 @@ struct yang_stmt{
                                         Y_TYPE & identity: store all derived 
                                            types as <module>:<id> list
                                         Y_UNIQUE: vector of descendant schema node ids
+                                        Y_EXTENSION: vector of instantiated UNKNOWNSo
                                      */
     yang_type_cache   *ys_typecache; /* If ys_keyword==Y_TYPE, cache all typedef data except unions */
     char              *ys_when_xpath; /* Special conditional for a "when"-associated augment/uses xpath */

lib/src/clixon_yang_module.c

@@ -192,8 +192,8 @@ yang_modules_revision(clicon_handle h)
  * If also CLICON_MODULE_LIBRARY_RFC7895 is set, module-state is built according to RFC7895 instead
  * @see RFC8525 
  */
-static int
+int
-yms_build(clicon_handle    h,
+yang_modules_state_build(clicon_handle    h,
                          yang_stmt       *yspec,
                          char            *msid,
                          int              brief,
@@ -361,7 +361,7 @@ yang_modules_state_get(clicon_handle    h,
             goto done;
         }
         /* Build a cb string: <modules-state>... */
-        if (yms_build(h, yspec, msid, brief, cb) < 0)
+        if (yang_modules_state_build(h, yspec, msid, brief, cb) < 0)
             goto done;
         /* Parse cb, x is on the form: <top><modules-state>... 
          * Note, list is not sorted since it is state (should not be)
@@ -391,7 +391,6 @@ yang_modules_state_get(clicon_handle    h,
         /* Remove everything that is not marked */
         if (xml_tree_prune_flagged_sub(x, XML_FLAG_MARK, 1, NULL) < 0)
             goto done;
-
         if ((ret = netconf_trymerge(x, yspec, xret)) < 0)
             goto done;
         if (ret == 0)

lib/src/clixon_yang_schema_mount.c

@@ -0,0 +1,346 @@
+/*
+ *
+  ***** BEGIN LICENSE BLOCK *****
+ 
+  Copyright (C) 2023 Olof Hagsand
+
+  This file is part of CLIXON.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+  Alternatively, the contents of this file may be used under the terms of
+  the GNU General Public License Version 3 or later (the "GPL"),
+  in which case the provisions of the GPL are applicable instead
+  of those above. If you wish to allow use of your version of this file only
+  under the terms of the GPL, and not to allow others to
+  use your version of this file under the terms of Apache License version 2, 
+  indicate your decision by deleting the provisions above and replace them with
+  the  notice and other provisions required by the GPL. If you do not delete
+  the provisions above, a recipient may use your version of this file under
+  the terms of any one of the Apache License version 2 or the GPL.
+
+  ***** END LICENSE BLOCK *****
+
+ * RFC 8525 Yang schema mount support
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "clixon_config.h" /* generated by config & autoconf */
+#endif
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <limits.h>
+#include <string.h>
+
+/* cligen */
+#include <cligen/cligen.h>
+
+/* clixon */
+#include "clixon_queue.h"
+#include "clixon_hash.h"
+#include "clixon_handle.h"
+#include "clixon_err.h"
+#include "clixon_log.h"
+#include "clixon_yang.h"
+#include "clixon_xml.h"
+#include "clixon_xml_io.h"
+#include "clixon_yang_module.h"
+#include "clixon_netconf_lib.h"
+
+#include "clixon_yang_schema_mount.h"
+
+/*! Check if y is a RFC 8525 YANG schema mount
+ *
+ * Check if:
+ * - y is CONTAINER or LIST, AND
+ * - y has YANG schema mount "mount-point" as child element, AND
+ * - the extension label matches y (see note below)
+ * If so, then return 1
+ * @param[in] y   Yang statement
+ * @retval    1   Yes, y is a RFC 8525 YANG mount-point
+ * @retval    0   No, y is not
+ * @retval   -1   Error
+ * @note That this may be a restriction on the usage of "label". The RFC is somewhat unclear.
+ */
+int
+yang_schema_mount_point(yang_stmt *y)
+{
+    int           retval = -1;
+    enum rfc_6020 keyw;
+    int           exist = 0;
+    char         *value = NULL;
+
+    if (y == NULL){
+        clicon_err(OE_YANG, EINVAL, "y is NULL");
+        goto done;
+    }
+    keyw = yang_keyword_get(y);
+    if (keyw != Y_CONTAINER && keyw != Y_LIST)
+        goto fail;
+    if (yang_extension_value(y, "mount-point", YANG_SCHEMA_MOUNT_NAMESPACE, &exist, &value) < 0)
+        goto done;
+    if (exist == 0)
+        goto fail;
+    if (value == NULL)
+        goto fail;
+    retval = 1;
+ done:
+    return retval;
+ fail:
+    retval = 0;
+    goto done;
+}
+
+/*! Find schema mounts - callback function for xml_apply
+ *
+ * @param[in]  x    XML node  
+ * @param[in]  arg  cvec, if match add node
+ * @retval    -1    Error, aborted at first error encounter, return -1 to end user
+ * @retval     0    OK, continue
+ * @retval     1    Abort, dont continue with others, return 1 to end user
+ * @retval     2    Locally abort this subtree, continue with others
+ */
+static int
+find_schema_mounts(cxobj *x,
+                   void  *arg)
+{
+    int        ret;
+    yang_stmt *y;
+    cvec      *cvv = (cvec *)arg;
+    cg_var    *cv;
+    
+    if ((y = xml_spec(x)) == NULL)
+        return 2;
+    if (yang_config(y) == 0)
+        return 2;
+    if ((ret = yang_schema_mount_point(y)) < 0)
+        return -1;
+    if (ret == 0)
+        return 0;
+    if ((cv = cvec_add(cvv, CGV_VOID)) == NULL){
+        clicon_err(OE_UNIX, errno, "cvec_add");
+        return -1;
+    }
+    cv_void_set(cv, x);
+    return 0;
+}
+ 
+/*! Find mount-points and return yang-library state
+ *
+ * Brute force: traverse whole XML, match all x that have ymount as yspec
+ * Add yang-library state for all x
+ * @param[in]     h       Clicon handle
+ * @param[in]     yspec   Yang spec
+ * @param[in]     xpath   XML Xpath
+ * @param[in]     nsc     XML Namespace context for xpath
+ * @param[in,out] xret    Existing XML tree, merge x into this
+ * @param[out]    xerr    XML error tree, if retval = 0
+ * @retval        1       OK
+ * @retval        0       Validation failed, error in xret
+ * @retval       -1       Error (fatal)
+ *
+ * RFC 8528 Section 3.4:
+ *   A schema for a mount point contained in a mounted module can be
+ *   specified by implementing the "ietf-yang-library" and
+ *   "ietf-yang-schema-mount" modules in the mounted schema and specifying
+ *   the schemas in exactly the same way as the top-level schema.
+ * Alt: see snmp_yang2xml to get instances instead of brute force traverse of whole tree
+ */
+static int
+schema_mounts_yang_library(clicon_handle h,
+                           yang_stmt    *yspec,
+                           char         *xpath,
+                           cvec         *nsc,
+                           cxobj       **xret,
+                           cxobj       **xerr)
+{
+    int     retval = -1;
+    cvec   *cvv = NULL;
+    cg_var *cv;
+    cxobj  *xmp;          /* xml mount-point */
+    cxobj  *xylib = NULL; /* xml yang-lib */
+    cbuf   *cb = NULL;
+    char   *msid = "mount-point"; /* modules-set-id dummy */
+
+    if ((cb = cbuf_new()) == NULL){
+        clicon_err(OE_UNIX, 0, "clicon buffer");
+        goto done;
+    }
+    if ((cvv = cvec_new(0)) == NULL){
+        clicon_err(OE_UNIX, errno, "cvec_new");
+        goto done;
+    }
+    if (xml_apply(*xret, CX_ELMNT, find_schema_mounts, cvv) < 0)
+        goto done;
+    cv = NULL;
+    while ((cv = cvec_each(cvv, cv)) != NULL) {
+        xmp = cv_void_get(cv);
+        /* addsub here */
+        cbuf_reset(cb);
+        // XXX change yspec to mount-point
+        /* Build a cb string: <modules-state>... */
+        if (yang_modules_state_build(h, yspec, msid, 0, cb) < 0)
+            goto done;
+        /* Parse cb, x is on the form: <top><modules-state>... 
+         * Note, list is not sorted since it is state (should not be)
+         */
+        if (clixon_xml_parse_string(cbuf_get(cb), YB_MODULE, yspec, &xylib, NULL) < 0){
+            if (xret && netconf_operation_failed_xml(xret, "protocol", clicon_err_reason)< 0)
+                goto done;
+            goto fail;
+        }
+        if (xml_rootchild(xylib, 0, &xylib) < 0)
+            goto done;
+        if (xml_addsub(xmp, xylib) < 0)
+            goto done;
+        xylib = NULL;
+    }
+    retval = 1;
+ done:
+    if (cvv)
+        cvec_free(cvv);
+    if (cb)
+        cbuf_free(cb);
+    return retval;
+ fail:
+    retval = 0;
+    goto done;
+}
+
+/*! Get modules state according to RFC 8528
+ *
+ * @param[in]     h       Clicon handle
+ * @param[in]     yspec   Yang spec
+ * @param[in]     xpath   XML Xpath
+ * @param[in]     nsc     XML Namespace context for xpath
+ * @param[in,out] xret    Existing XML tree, merge x into this
+ * @param[out]    xerr    XML error tree, if retval = 0
+ * @retval        1       OK
+ * @retval        0       Validation failed, error in xret
+ * @retval       -1       Error (fatal)
+ * @note  Only "inline" specification of mounted schema supported, not "shared schema"
+ */
+int
+schema_mounts_state_get(clicon_handle h,
+                        yang_stmt    *yspec,
+                        char         *xpath,
+                        cvec         *nsc,
+                        cxobj       **xret,
+                        cxobj       **xerr)
+{
+    int        retval = -1;
+    cbuf      *cb = NULL;
+    int        ret;
+    yang_stmt *yext;
+    yang_stmt *ymount;
+    yang_stmt *ymodext;
+    yang_stmt *ymod;
+    cg_var    *cv;
+    cg_var    *cv1;
+    char      *label;
+    cvec      *cvv;
+    cxobj     *x1 = NULL;
+
+    if ((ymodext = yang_find(yspec, Y_MODULE, "ietf-yang-schema-mount")) == NULL ||
+        (yext = yang_find(ymodext, Y_EXTENSION, "mount-point")) == NULL){
+        goto ok;
+        //        clicon_err(OE_YANG, 0, "yang schema mount-point extension not found");
+        //        goto done;
+    }
+    if ((cvv = yang_cvec_get(yext)) != NULL){
+        if ((cb = cbuf_new()) ==NULL){
+            clicon_err(OE_XML, errno, "cbuf_new");
+            goto done;
+        }
+        cprintf(cb, "<schema-mounts xmlns=\"%s\">", YANG_SCHEMA_MOUNT_NAMESPACE); // XXX only if hit
+        cv = NULL;
+        while ((cv = cvec_each(cvv, cv)) != NULL){
+            ymount = (yang_stmt*)cv_void_get(cv);
+            ymod = ys_module(ymount);
+            if ((cv1 = yang_cv_get(ymount)) == NULL){
+                clicon_err(OE_YANG, 0, "mount-point extension must have label");
+                goto done;
+            }
+            label = cv_string_get(cv1);
+            cprintf(cb, "<mount-point>");
+            cprintf(cb, "<module>%s</module>", yang_argument_get(ymod));
+            cprintf(cb, "<label>%s</label>", label);
+            cprintf(cb, "<inline/>");
+            cprintf(cb, "</mount-point>");
+        }
+        cprintf(cb, "</schema-mounts>");
+        if ((ret = clixon_xml_parse_string(cbuf_get(cb), YB_MODULE, yspec, &x1, xerr)) < 0)
+            goto done;
+        if (ret == 0)
+            goto fail;
+        if ((ret = netconf_trymerge(x1, yspec, xret)) < 0)
+            goto done;
+        if (ret == 0)
+            goto fail;
+    }
+    /* Find mount-points and return yang-library state */
+    if (0 && schema_mounts_yang_library(h, yspec, xpath, nsc, xret, xerr) < 0)
+        goto done;
+ ok:
+    retval = 1;
+ done:
+    if (x1)
+        xml_free(x1);
+    if (cb)
+        cbuf_free(cb);
+    return retval;
+ fail:
+    retval = 0;
+    goto done;
+}
+
+/*! Callback for yang schema mount-point extension
+ * 
+ * @param[in] h    Clixon handle
+ * @param[in] yext Yang node of extension 
+ * @param[in] ys   Yang node of (unknown) statement belonging to extension
+ * @retval     0   OK
+ * @retval    -1   Error
+    // XXX his may not even be necessary
+ */
+int
+yang_schema_unknown(clicon_handle h,
+                    yang_stmt    *yext,
+                    yang_stmt    *ys)
+{
+    int        retval = -1;
+    char      *extname;
+    char      *modname;
+    yang_stmt *ymod;
+    cg_var    *cv;
+    char      *label;
+
+    ymod = ys_module(yext);
+    modname = yang_argument_get(ymod);
+    extname = yang_argument_get(yext);
+    if (strcmp(modname, "ietf-yang-schema-mount") != 0 || strcmp(extname, "mount-point") != 0)
+        goto ok;
+    if ((cv = yang_cv_get(ys)) == NULL){
+        clicon_err(OE_YANG, 0, "mount-point extension must have label");
+        goto done;
+    }
+    label = cv_string_get(cv);
+    clicon_debug(1, "%s Enabled extension:%s:%s label:%s", __FUNCTION__, modname, extname, label);
+    // XXX his may not even be necessary
+ ok:
+    retval = 0;
+ done:
+    return retval;
+}