* Notification event streams enhancements

* Yang 1.1 notification support
  * Event stream discovery support according to RFC 5277 Sec 3.2.5.1 (netconf) and RFC 8040 (restconf)

apps/backend/backend_client.c

@@ -99,20 +99,10 @@ client_subscription_add(struct client_entry *ce,
     return su;
 }
 
-static struct client_entry *
-ce_find_bypid(struct client_entry *ce_list, int pid)
-{
-    struct client_entry *ce;
-
-    for (ce = ce_list; ce; ce = ce->ce_next)
-	if (ce->ce_pid == pid)
-	    return ce;
-    return NULL;
-}
-
+/*! Delete stream subscription from client subscription list */
 static int
 client_subscription_delete(struct client_entry *ce, 
-		    struct client_subscription *su0)
+			   struct client_subscription *su0)
 {
     struct client_subscription   *su;
     struct client_subscription  **su_prev;
@@ -134,7 +124,8 @@ client_subscription_delete(struct client_entry *ce,
 
 #ifdef notused /* xxx */
 static struct client_subscription *
-client_subscription_find(struct client_entry *ce, char *stream)
+client_subscription_find(struct client_entry *ce,
+			 char *stream)
 {
     struct client_subscription   *su = NULL;
 
@@ -146,6 +137,18 @@ client_subscription_find(struct client_entry *ce, char *stream)
 }
 #endif 
 
+static struct client_entry *
+ce_find_bypid(struct client_entry *ce_list,
+	      int pid)
+{
+    struct client_entry *ce;
+
+    for (ce = ce_list; ce; ce = ce->ce_next)
+	if (ce->ce_pid == pid)
+	    return ce;
+    return NULL;
+}
+
 /*! Remove client entry state
  * Close down everything wrt clients (eg sockets, subscriptions)
  * Finally actually remove client struct in handle
@@ -258,6 +261,79 @@ from_client_get_config(clicon_handle h,
     return retval;
 }
 
+static int
+client_get_streams(clicon_handle        h,
+		   char                *xpath,
+		   cxobj              **xtop)
+{
+    int            retval = -1;
+    cxobj         *x = NULL;
+    cxobj         *xc;
+    char          *reason = NULL;
+    yang_spec     *yspec;
+    cbuf          *cb;
+
+    if ((yspec =  clicon_dbspec_yang(h)) == NULL){
+	clicon_err(OE_YANG, ENOENT, "No yang spec");
+	goto done;
+    }
+    if (*xtop==NULL){
+	clicon_err(OE_CFG, ENOENT, "XML tree expected");
+	goto done;
+    }
+    if ((cb = cbuf_new()) == NULL){
+	clicon_err(OE_UNIX, 0, "clicon buffer");
+	goto done;
+    }
+    cprintf(cb,"<restconf-state xmlns=\"urn:ietf:params:xml:ns:yang:ietf-restconf-monitoring\">");
+    if (stream_get_xml(h, cb) < 0)
+	goto done;
+    cprintf(cb,"</restconf-state>");
+    /* XXX. yspec */
+    if (xml_parse_string(cbuf_get(cb), NULL, &x) < 0)
+	goto done;
+    if (xml_merge(*xtop, x, yspec, &reason) < 0)
+	goto done;
+    if (reason){
+	while ((xc = xml_child_i(*xtop, 0)) != NULL)
+	    xml_purge(xc);	    
+	if (netconf_operation_failed_xml(xtop, "rpc", reason)< 0)
+	    goto done;
+	goto ok;
+    }
+#ifdef notyet
+    /* Code complex to filter out anything that is outside of xpath */
+    if (xpath_vec(*xtop, "%s", &xvec, &xlen, xpath?xpath:"/") < 0)
+	goto done;
+
+    /* If vectors are specified then mark the nodes found and
+     * then filter out everything else,
+     * otherwise return complete tree.
+     */
+    if (xvec != NULL){
+	for (i=0; i<xlen; i++)
+	    xml_flag_set(xvec[i], XML_FLAG_MARK);
+    }
+    /* Remove everything that is not marked */
+    if (!xml_flag(*xtop, XML_FLAG_MARK))
+	if (xml_tree_prune_flagged_sub(*xtop, XML_FLAG_MARK, 1, NULL) < 0)
+	    goto done;
+    /* reset flag */
+    if (xml_apply(*xtop, CX_ELMNT, (xml_applyfn_t*)xml_flag_reset, (void*)XML_FLAG_MARK) < 0)
+	goto done;
+#endif
+ ok:
+    retval = 0;
+ done:
+    if (cb)
+	cbuf_free(cb);
+    if (reason)
+	free(reason);
+    if (x)
+	xml_free(x);
+    return retval;
+}
+
 /*! Internal message: get
  * 
  * @param[in]  h     Clicon handle
@@ -288,6 +364,11 @@ from_client_get(clicon_handle h,
     }
     /* Get state data from plugins as defined by plugin_statedata(), if any */
     assert(xret);
+
+#if 1 /* get netconf state data */
+    if ((ret = client_get_streams(h, selector, &xret)) < 0)
+	goto done;
+#endif
     clicon_err_reset();
     if ((ret = clixon_plugin_statedata(h, selector, &xret)) < 0)
 	goto done;

apps/backend/backend_main.c

@@ -756,6 +756,11 @@ main(int    argc,
 	return -1;
     }
 
+    if (stream_register(h, "NETCONF", "default NETCONF event stream") < 0)
+	goto done;
+    if (stream_register(h, "CLICON", "Clicon logs") < 0)
+	goto done;
+	
     if ((xmldb_plugin = clicon_xmldb_plugin(h)) == NULL){
 	clicon_log(LOG_ERR, "No xmldb plugin given (specify option CLICON_XMLDB_PLUGIN).\n"); 
 	goto done;
@@ -765,10 +770,11 @@ main(int    argc,
     /* Connect to plugin to get a handle */
     if (xmldb_connect(h) < 0)
 	goto done;
-    /* Parse db spec file */
+    /* Read and parse application yang specification */
     if (yang_spec_main(h) == NULL)
 	goto done;
-
+    if (yang_spec_append(h, CLIXON_DATADIR, "ietf-restconf-monitoring", NULL)< 0)
+	goto done;
     /* Set options: database dir and yangspec (could be hidden in connect?)*/
     if (xmldb_setopt(h, "dbdir", clicon_xmldb_dir(h)) < 0)
 	goto done;

apps/backend/clixon_backend_handle.c

@@ -86,6 +86,8 @@ struct backend_handle {
     int                      bh_magic;     /* magic (HDR)*/
     clicon_hash_t           *bh_copt;      /* clicon option list (HDR) */
     clicon_hash_t           *bh_data;      /* internal clicon data (HDR) */
+    event_stream_t          *ch_stream;   /* notification streams, see clixon_stream.[ch] */
+    
     /* ------ end of common handle ------ */
     struct client_entry     *bh_ce_list;   /* The client list */
     int                      bh_ce_nr;     /* Number of clients, just increment */

apps/cli/cli_handle.c

@@ -76,14 +76,14 @@
  * @see struct clicon_handle, struct backend_handle
  */
 struct cli_handle {
-    int                      cl_magic;    /* magic (HDR)*/
-    clicon_hash_t           *cl_copt;     /* clicon option list (HDR) */
-    clicon_hash_t           *cl_data;     /* internal clicon data (HDR) */
+    int             cl_magic;    /* magic (HDR)*/
+    clicon_hash_t  *cl_copt;     /* clicon option list (HDR) */
+    clicon_hash_t  *cl_data;     /* internal clicon data (HDR) */
+    event_stream_t *cl_stream;   /* notification streams, see clixon_stream.[ch] */
     /* ------ end of common handle ------ */
-    cligen_handle            cl_cligen;   /* cligen handle */
-
-    cli_syntax_t *cl_stx;	           /* syntax structure */
 
+    cligen_handle   cl_cligen;   /* cligen handle */
+    cli_syntax_t   *cl_stx;	/* syntax structure */
 };
 
 /*! Return a clicon handle for other CLICON API calls

apps/restconf/README.md

@@ -7,11 +7,13 @@ Ensure www-data is member of the CLICON_SOCK_GROUP (default clicon). If not, add
   sudo usermod -a -G clicon www-data
 ```
 
+This implementation uses FastCGI, see http://www.mit.edu/~yandros/doc/specs/fcgi-spec.html.
+
 Define nginx config file: /etc/nginx/sites-available/default
 ```
 server {
   ...
-  location /restconf {
+  location / {
     root /usr/share/nginx/html/restconf;
     fastcgi_pass unix:/www-data/fastcgi_restconf.sock;
     include fastcgi_params;