- Yang deviation [deviation statement not yet support #211](https://github.com/clicon/clixon/issues/211)

- Added "depth" parameter to yang_apply
- Added extra API function to yang_cardinality to check individual relation

CHANGELOG.md

@@ -36,7 +36,8 @@ Expected: June 2021
 
 * Yang Deviation/deviate [deviation statement not yet support #211](https://github.com/clicon/clixon/issues/211)
   * See RFC7950 Sec 5.6.3
-  * Work-in-progress
+  * Implemented: "not-supported" and "add"
+  * Not yet: "replace" and "delete"
 
 ### Minor features
 

lib/clixon/clixon_yang.h

@@ -238,12 +238,12 @@ int        yang_order(yang_stmt *y);
 int        yang_print_cb(FILE *f, yang_stmt *yn, clicon_output_cb *fn);
 int        yang_print(FILE *f, yang_stmt *yn);
 int        yang_print_cbuf(cbuf *cb, yang_stmt *yn, int marginal);
+int        yang_deviation(yang_stmt *ys, void *arg);
 int        yang_spec_dump(yang_stmt *yspec, int debuglevel);
 int        if_feature(yang_stmt *yspec, char *module, char *feature);
 int        ys_populate(yang_stmt *ys, void *arg);
 int        ys_populate2(yang_stmt *ys, void *arg);
-int        yang_apply(yang_stmt *yn, enum rfc_6020 key, yang_applyfn_t fn, 
+int        yang_apply(yang_stmt *yn, enum rfc_6020 key, yang_applyfn_t fn, int from, void *arg);
-		      void *arg);
 int        yang_datanode(yang_stmt *ys);
 int        yang_abs_schema_nodeid(yang_stmt *ys, char *schema_nodeid, yang_stmt **yres);
 int        yang_desc_schema_nodeid(yang_stmt *yn, char *schema_nodeid, yang_stmt **yres);

lib/src/clixon_yang.c

@@ -513,6 +513,40 @@ ys_prune(yang_stmt *yp,
     return yc;
 }
 
+/*! Remove yang node from parent (dont free
+ * @param[in]  ys   Yang node to remove
+ * @retval     0    OK
+ * @retval     -1   Error
+ * @see ys_prune  if parent and position is known
+ * @note Do not call this in a loop of yang children (unless you know what you are doing)
+ */
+static int
+ys_prune_self(yang_stmt *ys)
+{
+    int        retval = -1;
+    yang_stmt *yp;
+    yang_stmt *yc;
+    int        i;
+
+    if ((yp = yang_parent_get(ys)) != NULL){
+	yc = NULL;
+	i = 0;
+	/* Find order of ys in child-list */
+	while ((yc = yn_each(yp, yc)) != NULL) {
+	    if (ys == yc)
+		break;
+	    i++;
+	}
+	if (yc != NULL){
+	    assert(yc == ys);
+	    ys_prune(yp, i);
+	}
+    }
+    retval = 0;
+    // done:
+    return retval;
+}
+
 /*! Free a yang statement tree recursively 
  * @param[in]  ys   Yang node to remove and all its children recursively
  * @note does not remove yang node from tree
@@ -1555,6 +1589,105 @@ yang_print_cbuf(cbuf      *cb,
     return 0;
 }
 
+/*! Yang deviation/deviate 
+ *
+ * Identify deviation target node, and go through all its deviate statements.
+ * Features/if-feature must have run before
+ * @param[in] ys    The yang deviation to populate.
+ * @param[in] h     Clicon handle
+ * @see RFC 7950 5.6.3 and 7.20.3
+ */
+int
+yang_deviation(yang_stmt *ys,
+	       void      *arg)
+
+{
+    int           retval = -1;
+    char         *nodeid; 
+    yang_stmt    *ytarget = NULL;
+    yang_stmt    *yd;
+    yang_stmt    *yc;
+    yang_stmt    *yc1;
+    char         *devop;
+    clicon_handle h = (clicon_handle)arg;
+    enum rfc_6020 kw;
+    int           min;
+    int           max;
+
+    if (yang_keyword_get(ys) != Y_DEVIATION)
+	goto ok;
+    /* Absolute schema node identifier identifying target node */
+    if ((nodeid = yang_argument_get(ys)) == NULL){
+	clicon_err(OE_YANG, EINVAL, "No argument to deviation");
+	goto done;
+    }
+    /* Get target node */
+    if (yang_abs_schema_nodeid(ys, nodeid, &ytarget) < 0)
+	goto done;
+    if (ytarget == NULL){ 
+	goto ok;
+	/* The RFC does not explicitly say the target node MUST exist 
+	clicon_err(OE_YANG, 0, "schemanode sanity check of %s", nodeid);
+	goto done;
+	*/
+    }
+    /* Go through deviates of deviation */
+    yd = NULL; 
+    while ((yd = yn_each(ys, yd)) != NULL) {
+	/* description / if-feature / reference */
+	if (yang_keyword_get(yd) != Y_DEVIATE)
+	    continue;
+	devop = yang_argument_get(yd);
+	if (strcmp(devop, "not-supported") == 0){
+	    if (ys_prune_self(ytarget) < 0)
+		goto done;
+	    if (ys_free(ytarget) < 0)
+		goto done;
+	    goto ok; /* Target node removed, no other deviates possible */
+	}
+	else if (strcmp(devop, "add") == 0){
+	    yc = NULL; 
+	    while ((yc = yn_each(yd, yc)) != NULL) {
+		/* If a property can only appear once, the property MUST NOT
+		   exist in the target node. */
+		kw = yang_keyword_get(yc);
+		if (yang_find(ytarget, kw, NULL) != NULL){
+		    if (yang_cardinality_interval(h,
+						  yang_keyword_get(ytarget),
+						  kw,
+						  &min,
+						  &max) < 0)
+			goto done;
+		    if (max == 1){
+			clicon_err(OE_YANG, 0, "deviation %s: \"%s %s\" added but node already exist in target %s",
+				   nodeid,
+				   yang_key2str(kw), yang_argument_get(yc),
+				   yang_argument_get(ytarget));
+			goto done;
+		    }
+		}
+		/* Make a copy of deviate child and insert. */
+		if ((yc1 = ys_dup(yc)) == NULL)
+		    goto done;
+		if (yn_insert(ytarget, yc1) < 0)
+		    goto done;
+	    }
+	}
+	else if (strcmp(devop, "replace") == 0){
+	}
+	else if (strcmp(devop, "delete") == 0){
+	}
+	else{ /* Shouldnt happen, lex/yacc takes it */
+	    clicon_err(OE_YANG, EINVAL, "%s: invalid deviate operator", devop);
+	    goto done;
+	}
+    }
+ ok:
+    retval = 0;
+ done:
+    return retval;
+}
+
 /*! Populate yang leafs after parsing. Create cv and fill it in.
  *
  * Populate leaf in 2nd round of yang parsing, now that context is complete:
@@ -2507,6 +2640,7 @@ yang_features(clicon_handle h,
  * @param[in]  yn   yang node
  * @param[in]  key  yang keyword to use as filer or -1 for all
  * @param[in]  fn   Callback
+ * @param[in]  depth Depth argument: where to start. If <=0 call the calling node yn, if 1 start with its children, etc
  * @param[in]  arg  Argument
  * @retval    -1    Error, aborted at first error encounter
  * @retval     0    OK, all nodes traversed
@@ -2516,7 +2650,7 @@ yang_features(clicon_handle h,
  * {
  *   return 0;
  * }
- * yang_apply(ys, Y_TYPE, ys_fn, NULL);
+ * yang_apply(ys, Y_TYPE, ys_fn, 1, NULL); // Call all yn:s children recursively
  * @endcode
  * @note do not delete or move around any children during this function
  */
@@ -2524,6 +2658,7 @@ int
 yang_apply(yang_stmt     *yn, 
 	   enum rfc_6020  keyword,
 	   yang_applyfn_t fn, 
+	   int            depth,
 	   void          *arg)
 {
     int        retval = -1;
@@ -2531,17 +2666,19 @@ yang_apply(yang_stmt     *yn,
     int        i;
     int        ret;
 
-    for (i=0; i<yn->ys_len; i++){
+    if (depth <= 0){
-	ys = yn->ys_stmt[i];
+	if ((int)keyword == -1 || keyword == yn->ys_keyword){
-	if ((int)keyword == -1 || keyword == ys->ys_keyword){
+	    if ((ret = fn(yn, arg)) < 0)
-	    if ((ret = fn(ys, arg)) < 0)
 		goto done;
 	    if (ret > 0){
 		retval = ret;
 		goto done;
 	    }
 	}
-	if ((ret = yang_apply(ys, keyword, fn, arg)) < 0)
+    }
+    for (i=0; i<yn->ys_len; i++){
+	ys = yn->ys_stmt[i];
+	if ((ret = yang_apply(ys, keyword, fn, depth-1, arg)) < 0)
 	    goto done;
 	if (ret > 0){
 	    retval = ret;

lib/src/clixon_yang_cardinality.c

@@ -459,7 +459,6 @@ ycard_find(enum rfc_6020       parent,
 	   enum rfc_6020       child,
 	   const struct ycard *yclist,
 	   int                 p)
-
 {
      const struct ycard *yc;
     
@@ -556,3 +555,32 @@ yang_cardinality(clicon_handle h,
     return retval;
 }
 
+/*! Return cardinality interval [min,max] given yang parent and child keyword.
+ *
+ * @param[in]  h        Clicon handle
+ * @param[in]  parent_key
+ * @param[in]  child_key
+ * @param[out] minp    0 or 1
+ * @param[out] maxp    1 or NMAX (large number)
+ */
+int
+yang_cardinality_interval(clicon_handle h,
+			  enum rfc_6020 parent_key,
+			  enum rfc_6020 child_key,
+			  int          *min,
+			  int          *max)
+{
+    int                 retval = -1;
+    const struct ycard *ycplist; /* ycard parent table*/
+    
+    if ((ycplist = ycard_find(parent_key, child_key, yclist, 0)) == NULL){
+	clicon_err(OE_YANG, EINVAL, "keys %d %d do not have cardinality",
+		   parent_key, child_key);
+	goto done;
+    }
+    *min = ycplist->yc_min;
+    *max = ycplist->yc_max;
+    retval = 0;
+ done:
+    return retval;
+}

lib/src/clixon_yang_cardinality.h

@@ -40,4 +40,6 @@
  */
 int yang_cardinality(clicon_handle h, yang_stmt *yt, char *modname);
 
+int yang_cardinality_interval(clicon_handle h, enum rfc_6020 parent_key, enum rfc_6020 child_key, int *min, int *max);
+
 #endif	/* _CLIXON_YANG_CARDINALITY_H_ */

lib/src/clixon_yang_parse_lib.c

@@ -1074,14 +1074,6 @@ ys_schemanode_check(yang_stmt *ys,
 	}
 	break;
     }
-    case Y_DEVIATION:
-	if (yang_abs_schema_nodeid(ys, arg, &yres) < 0)
-	    goto done;
-	if (yres == NULL){
-	    clicon_err(OE_YANG, 0, "schemanode sanity check of %s", arg);
-	    goto done;
-	}
-	break;
     default:
 	break;
     }
@@ -1331,20 +1323,26 @@ yang_parse_post(clicon_handle h,
 	if (yang_features(h, yang_child_i(yspec, i)) < 0)
 	    goto done;
 
-    /* 4: Go through parse tree and populate it with cv types */
+    /* 4: Check deviations: not-supported add/delete/replace statements 
-    for (i=modmin; i<modmax; i++){
+     *    done after if-features since they may affect deviations but before populate since target yang statements
-	if (ys_populate(yang_child_i(yspec, i), h) < 0) /* Alt: make a yang_apply0 */
+     *    may be removed or changed
+     */
+    for (i=modmin; i<modmax; i++) /* Really only under (sub)modules no need to traverse whole tree */
+	if (yang_apply(yang_child_i(yspec, i), -1, yang_deviation, 1, (void*)h) < 0)
 	    goto done;
-	if (yang_apply(yang_child_i(yspec, i), -1, ys_populate, (void*)h) < 0)
+    
+    /* 5: Go through parse tree and populate it with cv types */
+    for (i=modmin; i<modmax; i++){
+	if (yang_apply(yang_child_i(yspec, i), -1, ys_populate, 0, (void*)h) < 0)
 	    goto done;
     }
 
-    /* 5: Resolve all types: populate type caches. Requires eg length/range cvecs
+    /* 6: Resolve all types: populate type caches. Requires eg length/range cvecs
      * from ys_populate step.
      * Must be done using static binding.
      */
     for (i=modmin; i<modmax; i++)
-	if (yang_apply(yang_child_i(yspec, i), Y_TYPE, ys_resolve_type, h) < 0)
+	if (yang_apply(yang_child_i(yspec, i), Y_TYPE, ys_resolve_type, 1, h) < 0)
 	    goto done;
 
     /* Up to here resolving is made in the context they are defined, rather 
@@ -1354,14 +1352,14 @@ yang_parse_post(clicon_handle h,
      * single tree as they are used.
      */
 
-    /* 6: Macro expansion of all grouping/uses pairs. Expansion needs marking */
+    /* 7: Macro expansion of all grouping/uses pairs. Expansion needs marking */
     for (i=0; i<ylen; i++){
 	if (yang_expand_grouping(ylist[i]) < 0)
 	    goto done;
-	yang_apply(ylist[i], -1, (yang_applyfn_t*)yang_flag_reset, (void*)YANG_FLAG_MARK);
+	yang_apply(ylist[i], -1, (yang_applyfn_t*)yang_flag_reset, 1, (void*)YANG_FLAG_MARK);
     }
 
-    /* 7: Top-level augmentation of all modules. 
+    /* 8: Top-level augmentation of all modules. 
      * Note: Clixon does not implement augment in USES 
      * Note: There is an ordering problem, where an augment in one module depends on an augment in
      * another module not yet augmented.
@@ -1370,21 +1368,21 @@ yang_parse_post(clicon_handle h,
 	if (yang_augment_module(ylist[i]) < 0)
 	    goto done;
 
-    /* 4: Go through parse tree and do 2nd step populate (eg default) */
+    /* 9: Go through parse tree and do 2nd step populate (eg default) */
     for (i=0; i<ylen; i++)
-	if (yang_apply(ylist[i], -1, ys_populate2, (void*)h) < 0)
+	if (yang_apply(ylist[i], -1, ys_populate2, 1, (void*)h) < 0)
 	    goto done;
 
-    /* 8: sanity checks of expanded yangs need more here */
+    /* 10: sanity checks of expanded yangs need more here */
     for (i=0; i<ylen; i++){
 	/* Check schemanode references */
-	if (yang_apply(ylist[i], -1, ys_schemanode_check, NULL) < 0)
+	if (yang_apply(ylist[i], -1, ys_schemanode_check, 1, NULL) < 0)
 	    goto done;
 	/* Check list key values */
 	if (ys_list_check(h, ylist[i]) < 0)
 	    goto done;
     }
-    /* 9. Check cardinality a second time after grouping/augment etc */
+    /* 11. Check cardinality a second time after grouping/augment etc */
     for (i=0; i<ylen; i++)
 	if (yang_cardinality(h, ylist[i], yang_argument_get(ylist[i])) < 0)
 	    goto done;

test/test_yang_deviation.sh

@@ -36,7 +36,7 @@ module example-base{
    namespace "urn:example:base";
    container system {
       must "daytime or time";
-       leaf daytime{
+      leaf daytime{ 	    /* not supported removes this */
          type string;
       }
       list name-server {
@@ -52,42 +52,24 @@ module example-base{
          } 
          leaf type {
             type string;
+	    /* add rule adds default here */
          } 
       }
    }
 }
 EOF
 
-# Example from RFC 7950 Sec 7.20.3.3
+# Args:
-cat <<EOF > $fyangdev
+# 0: daytime implemented: true/false
-module $APPNAME{
+# 1: admin type default: true/false
-   yang-version 1.1;
+function testrun()
-   prefix md;
+{
-   namespace "urn:example:deviations";
+    daytime=$1
+    admindefault=$2
     
-   import example-base {
+    new "test params: -f $cfg"
-         prefix base;
-   }
 
-   deviation /base:system/base:daytime {
+    if [ "$BE" -ne 0 ]; then
-        deviate not-supported;
-   }
-   deviation /base:system/base:user/base:type {
-       deviate add {
-         default "admin"; // new users are 'admin' by default
-       }
-   }
-   deviation /base:system {
-       deviate delete {
-         must "daytime or time";
-       }
-   }
-}
-EOF
-
-new "test params: -f $cfg"
-
-if [ "$BE" -ne 0 ]; then
 	new "kill old backend"
 	sudo clixon_backend -zf "$cfg"
 	if [ $? -ne 0 ]; then
@@ -95,24 +77,95 @@ if [ "$BE" -ne 0 ]; then
 	fi
 	new "start backend -s init -f $cfg"
 	start_backend -s init -f "$cfg"
+    fi
 
-    new "waiting"
+    new "wait backend"
     wait_backend
-fi
 
+    if ! $daytime; then # Not supported - dont continue
+	new "Add example-base daytime - should not be supported"
+	expecteof "$clixon_netconf -qf $cfg" 0 "$DEFAULTHELLO<rpc $DEFAULTNS><edit-config><target><candidate/></target><config><system xmlns=\"urn:example:base\"><daytime>Sept17</daytime></system></config></edit-config></rpc>]]>]]>" "<rpc-reply $DEFAULTNS><rpc-error><error-type>application</error-type><error-tag>unknown-element</error-tag><error-info><bad-element>daytime</bad-element></error-info><error-severity>error</error-severity><error-message>Failed to find YANG spec of XML node: daytime with parent: system in namespace: urn:example:base</error-message></rpc-error></rpc-reply>]]>]]"
+    else
+	new "Add example-base daytime - supported"
+	expecteof "$clixon_netconf -qf $cfg" 0 "$DEFAULTHELLO<rpc $DEFAULTNS><edit-config><target><candidate/></target><config><system xmlns=\"urn:example:base\"><daytime>Sept17</daytime></system></config></edit-config></rpc>]]>]]>" "<rpc-reply $DEFAULTNS><ok/></rpc-reply>]]>]]"
 
-if [ "$BE" -eq 0 ]; then
+	new "Add user bob"
-    exit # BE
+	expecteof "$clixon_netconf -qf $cfg" 0 "$DEFAULTHELLO<rpc $DEFAULTNS><edit-config><target><candidate/></target><config><system xmlns=\"urn:example:base\"><user><name>bob</name></user></system></config></edit-config></rpc>]]>]]>" "<rpc-reply $DEFAULTNS><ok/></rpc-reply>]]>]]"
-fi
 
-new "Kill backend"
+	new "netconf commit"
-# Check if premature kill
+	expecteof "$clixon_netconf -qf $cfg" 0 "$DEFAULTHELLO<rpc $DEFAULTNS><commit/></rpc>]]>]]>" "^<rpc-reply $DEFAULTNS><ok/></rpc-reply>]]>]]>$"
-pid=$(pgrep -u root -f clixon_backend)
+	
-if [ -z "$pid" ]; then
+	if $admindefault; then 
+	    new "Get type admin expected"
+	    expecteof "$clixon_netconf -qf $cfg" 0 "$DEFAULTHELLO<rpc $DEFAULTNS><get-config><source><running/></source><filter type=\"xpath\" select=\"/base:system/base:user[base:name='bob']\" xmlns:base=\"urn:example:base\"/></get-config></rpc>]]>]]>" "^<rpc-reply $DEFAULTNS><data><system xmlns=\"urn:example:base\"><user><name>bob</name><type>admin</type></user></system></data></rpc-reply>]]>]]>$"
+# XXX Cannot select a default value??	    
+#	    expecteof "$clixon_netconf -qf $cfg" 0 "$DEFAULTHELLO<rpc $DEFAULTNS><get-config><source><running/></source><filter type=\"xpath\" select=\"/base:system/base:user[base:name='bob']/base:type\" xmlns:base=\"urn:example:base\"/></get-config></rpc>]]>]]>" foo
+	else
+	    new "Get type none expected"
+	    expecteof "$clixon_netconf -qf $cfg" 0 "$DEFAULTHELLO<rpc $DEFAULTNS><get-config><source><running/></source><filter type=\"xpath\" select=\"/base:system/base:user[base:name='bob']/base:type\" xmlns:base=\"urn:example:base\"/></get-config></rpc>]]>]]>" "^<rpc-reply $DEFAULTNS><data/></rpc-reply>]]>]]>$"
+	fi
+    fi
+    if [ "$BE" -ne 0 ]; then
+	new "Kill backend"
+	# Check if premature kill
+	pid=$(pgrep -u root -f clixon_backend)
+	if [ -z "$pid" ]; then
 	    err "backend already dead"
-fi
+	fi
-# kill backend
+	# kill backend
-stop_backend -f "$cfg"
+	stop_backend -f "$cfg"
+    fi
+} # testrun
+
+# Example from RFC 7950 Sec 7.20.3.3
+cat <<EOF > $fyangdev
+module example-deviations{
+   yang-version 1.1;
+   prefix md;
+   namespace "urn:example:deviations";
+   import example-base {
+         prefix base;
+   }
+}
+EOF
+new "daytime supported"
+testrun true false
+
+# Example from RFC 7950 Sec 7.20.3.3
+cat <<EOF > $fyangdev
+module example-deviations{
+   yang-version 1.1;
+   prefix md;
+   namespace "urn:example:deviations";
+   import example-base {
+         prefix base;
+   }
+   deviation /base:system/base:daytime {
+      deviate not-supported;
+   }
+}
+EOF
+new "daytime not supported"
+testrun false false
+
+# Example from RFC 7950 Sec 7.20.3.3
+cat <<EOF > $fyangdev
+module example-deviations{
+   yang-version 1.1;
+   prefix md;
+   namespace "urn:example:deviations";
+   import example-base {
+         prefix base;
+   }
+   deviation /base:system/base:user/base:type {
+      deviate add {
+         default "admin"; // new users are 'admin' by default
+      }
+   }
+}
+EOF
+new "deviate add, check admin default"
+testrun true true
 
 rm -rf "$dir"