Add support for custom snmp-keys

This commit adds support for defining a
different table/list keys for snmp and
yang lists.

The definition is being done using the
cx-snmp:table-key extension.

Solves #399

apps/snmp/snmp_handler.c

@@ -864,12 +864,12 @@ snmp_table_get(clixon_handle               h,
     yang_stmt *ys;
     yang_stmt *yk;
     char      *xpath = NULL;
-    cvec      *cvk_orig;
     cvec      *cvk_val = NULL;
     int        i;
     cg_var    *cv;
     char      *defaultval = NULL;
     int        ret;
+    clicon_debug(1, "%s", __FUNCTION__);
 
     /* Get yang of leaf from first part of OID */
     ys = NULL;
@@ -895,18 +895,14 @@ snmp_table_get(clixon_handle               h,
      */
     if (yang_extension_value_opt(ys, "smiv2:defval", NULL, &defaultval) < 0)
         goto done;
-
     /* Create xpath with right keys from later part of OID 
      * Inverse of snmp_str2oid
      */
-    if ((cvk_orig = yang_cvec_get(yt)) == NULL){
-        clixon_err(OE_YANG, 0, "No keys");
-        goto done;
-    }
-    if ((cvk_val = cvec_dup(cvk_orig)) == NULL){
-        clixon_err(OE_UNIX, errno, "cvec_dup");
+    if (clixon_snmp_ylist_keys(yt, &cvk_val) < 0) {
+        clixon_err(OE_XML, errno, "clixon_snmp_ylist_keys");
         goto done;
     }
+
     /* read through keys and create cvk */
     oidilen = oidslen-(oidtlen+1);
     oidi = oids+oidtlen+1;
@@ -981,7 +977,6 @@ snmp_table_set(clixon_handle               h,
     yang_stmt *yk;
     yang_stmt *yrestype = NULL;
     char      *xpath = NULL;
-    cvec      *cvk_orig;
     cvec      *cvk_val = NULL;
     int        i;
     cg_var    *cv;
@@ -990,6 +985,7 @@ snmp_table_set(clixon_handle               h,
     netsnmp_variable_list  *requestvb;
     int        rowstatus = 0;
     char      *origtype;
+    clicon_debug(1, "%s", __FUNCTION__);
 
     /* Get OID from table /list  */
     if ((ret = yangext_oid_get(yt, oidt, &oidtlen, NULL)) < 0)
@@ -1063,12 +1059,9 @@ snmp_table_set(clixon_handle               h,
     /* Create xpath with right keys from later part of OID 
      * Inverse of snmp_str2oid
      */
-    if ((cvk_orig = yang_cvec_get(yt)) == NULL){
-        clixon_err(OE_YANG, 0, "No keys");
-        goto done;
-    }
-    if ((cvk_val = cvec_dup(cvk_orig)) == NULL){
-        clixon_err(OE_UNIX, errno, "cvec_dup");
+
+    if (clixon_snmp_ylist_keys(yt, &cvk_val) < 0) {
+        clixon_err(OE_XML, errno, "clixon_snmp_ylist_keys");
         goto done;
     }
     /* read through keys and create cvk */
@@ -1190,7 +1183,7 @@ snmp_table_getnext(clixon_handle               h,
     yang_stmt *ycol;
     yang_stmt *ys;
     int        ret;
-    cvec      *cvk_name;
+    cvec      *cvk_name = NULL;
     oid        oidc[MAX_OID_LEN] = {0,}; /* Table / list oid */
     size_t     oidclen = MAX_OID_LEN;
     oid        oidk[MAX_OID_LEN] = {0,}; /* Key oid */
@@ -1220,7 +1213,7 @@ snmp_table_getnext(clixon_handle               h,
     }
     if ((xtable = xpath_first(xt, nsc, "%s", xpath)) != NULL) {
         /* Make a clone of key-list, but replace names with values */
-        if ((cvk_name = yang_cvec_get(ylist)) == NULL){
+        if (clixon_snmp_ylist_keys(ylist, &cvk_name) < 0){
             clixon_err(OE_YANG, 0, "No keys");
             goto done;
         }
@@ -1268,6 +1261,8 @@ snmp_table_getnext(clixon_handle               h,
     }
     retval = found;
  done:
+    if (cvk_name)
+        cvec_free(cvk_name);
     if (cb)
         cbuf_free(cb);
     if (xpath)

apps/snmp/snmp_lib.c

@@ -1030,7 +1030,7 @@ snmp_yang2xpath_cb(yang_stmt *ys,
     }
     switch (yang_keyword_get(ys)){
     case Y_LIST:
-        if ((cvk = yang_cvec_get(ys)) == NULL) /* Use Y_LIST cache, see ys_populate_list() */
+        if (clixon_snmp_ylist_keys(ys, &cvk) < 0)
             break;
         /* Iterate over individual keys  */
         assert(keyvec && cvec_len(cvk) == cvec_len(keyvec));
@@ -1042,6 +1042,7 @@ snmp_yang2xpath_cb(yang_stmt *ys,
                     cv_string_get(cvec_i(cvk, i)),
                     cv_string_get(cvec_i(keyvec, i)));
         }
+        cvec_free(cvk);
         break;
     case Y_LEAF_LIST:
         assert(0); // NYI
@@ -1389,3 +1390,41 @@ clixon_snmp_api_oid_find(oid   *oid0,
     // done:
     return retval;
 }
+
+/*! Get an SNMP key list from a ylist. 
+ * @param[in]  ylist   ylist 
+ * @param[out] ylist_keys  Vector of key names (strings). 
+ * @retval -1 Error
+ * @retval  0 OK
+ * Note: ylist_keys need to be freed.
+ */
+int clixon_snmp_ylist_keys(yang_stmt *ylist, cvec **ylist_keys) {
+    int retval = -1;
+    cvec *cvk = NULL;
+    char *smi_key_name = NULL;
+    if (yang_extension_value(ylist, "table-key", CLIXON_SNMP_NS, NULL, &smi_key_name) < 0){ 
+        clicon_err(OE_XML, errno, "could not lookup table-key");
+        goto done;
+    }
+
+    if (!smi_key_name){
+        /* Keys, go through keys */
+        if ((cvk = yang_cvec_get(ylist)) == NULL){
+            clicon_err(OE_YANG, 0, "No keys");
+            goto done;
+        }
+
+        cvk = cvec_dup(cvk);
+    } else {
+        cvk = cvec_new(0);
+        if (cvec_add_string(cvk, NULL, smi_key_name) < 0){
+            clicon_err(OE_UNIX, 0, "Could not add key");
+            goto done;
+        }
+    }
+
+    *ylist_keys = cvk;
+    retval = 0;
+done:
+    return retval;
+}

apps/snmp/snmp_lib.h

@@ -48,6 +48,7 @@ extern "C" {
 #define CLIXON_ERR_SNMP_MIB 0x1000
 
 #define IETF_YANG_SMIV2_NS "urn:ietf:params:xml:ns:yang:ietf-yang-smiv2"
+#define CLIXON_SNMP_NS "http://clicon.org/snmp"
 
 /* Special case/extended Clixon ASN1 types
  * Set in type_yang2asn1() if extended is true
@@ -107,6 +108,7 @@ int    snmp_str2oid(char *str, yang_stmt *yi, oid *objid, size_t *objidlen);
 int    snmp_oid2str(oid **oidi, size_t *oidilen, yang_stmt *yi, cg_var *cv);
 int    clixon_snmp_err_cb(void *handle, int suberr, cbuf *cb);
 int    snmp_xmlkey2val_oid(cxobj *xrow, cvec *cvk_name, cvec **cvk_orig, oid *objidk, size_t *objidklen);
+int    clixon_snmp_ylist_keys(yang_stmt *ylist, cvec **ylist_keys);
 
 /*========== libnetsnmp-specific code =============== */
 int    clixon_snmp_api_agent_check(void);

apps/snmp/snmp_register.c

@@ -285,11 +285,12 @@ mibyang_table_register(clixon_handle h,
         clixon_err(OE_UNIX, errno, "SNMP_MALLOC_TYPEDEF");
         goto done;
     }
-    /* Keys, go through keys */
-    if ((cvk = yang_cvec_get(ylist)) == NULL){
-        clixon_err(OE_YANG, 0, "No keys");
+
+    if (clixon_snmp_ylist_keys(ylist, &cvk) < 0) {
+        clixon_err(OE_XML, errno, "clixon_snmp_ylist_keys");
         goto done;
     }
+
     cvi = NULL;
     /* Iterate over individual keys  */
     while ((cvi = cvec_each(cvk, cvi)) != NULL) {
@@ -331,6 +332,9 @@ mibyang_table_register(clixon_handle h,
  ok:
     retval = 0;
  done:
+    if (cvk)
+        cvec_free(cvk);
+
     return retval;
 }
 
@@ -496,7 +500,8 @@ mibyang_table_poll(clixon_handle h,
     }
     if ((xtable = xpath_first(xt, nsc, "%s", xpath)) != NULL) {
         /* Make a clone of key-list, but replace names with values */
-        if ((cvk_name = yang_cvec_get(ylist)) == NULL){
+
+        if (clixon_snmp_ylist_keys(ylist, &cvk_name) < 0){
             clixon_err(OE_YANG, 0, "No keys");
             goto done;
         }
@@ -517,6 +522,8 @@ mibyang_table_poll(clixon_handle h,
     }
     retval = 0;
  done:
+    if (cvk_name)
+        cvec_free(cvk_name);
     if (xpath)
         free(xpath);
     if (cvk_val)

yang/clixon/Makefile.in

@@ -48,6 +48,7 @@ YANGSPECS	+= clixon-rfc5277@2008-07-01.yang
 YANGSPECS	+= clixon-xml-changelog@2019-03-21.yang
 YANGSPECS	+= clixon-restconf@2022-08-01.yang # 5.9
 YANGSPECS	+= clixon-autocli@2023-09-01.yang  # 6.4
+YANGSPECS	+= clixon-snmp@2023-01-17.yang
 
 all:	
 

yang/clixon/clixon-snmp@2023-01-17.yang

@@ -0,0 +1,55 @@
+module clixon-snmp{
+    yang-version 1.1;
+    namespace "http://clicon.org/snmp";
+    prefix cx-snmp;
+
+    organization
+        "Clicon / Clixon";
+
+    contact
+        "Olof Hagsand <olof@hagsand.se>";
+
+    description
+        "Clixon SNMP-specific extensions.
+         Design inspired by ietf-netconf-acm.yang
+      
+       ***** BEGIN LICENSE BLOCK *****
+       Copyright (C) 2020-2021 Olof Hagsand and Rubicon Communications, LLC(Netgate)
+       
+       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 *****";
+
+
+    revision 2023-01-17 {
+        description
+            "Initial version";
+    }
+    extension table-key {
+        argument key-name;
+
+        description 
+            "Selects an alternative key for an SNMP table represented by the YANG list.";
+    }
+}