Add RPC for injecting messages in the system log

doc/ChangeLog.md

@@ -19,6 +19,12 @@ All notable changes to the project are documented in this file.
 
 ### Added
 
+- Add a `log` RPC to `infix-syslog`, and a matching admin-exec `log`
+  command in the CLI, for injecting messages in the system log over
+  NETCONF/RESTCONF, issue #1639.  The full RFC 5424 header is supported:
+  severity, facility, app-name, msgid, and structured data.  Messages
+  are time stamped on arrival and follow the configured syslog filtering
+  and forwarding rules, like any locally generated message
 - Add `/system/advanced` for low-level system customization, issue #463:
   - `rc.d`: user scripts stored in the configuration, run once at boot
     after the startup configuration has been applied, in the order listed

doc/syslog.md

@@ -138,6 +138,64 @@ admin@example:/config/syslog/…/file:foobar/> <b>leave</b>
 admin@example:/>
 </code></pre>
 
+## Logging Messages
+
+Scripts and test systems can add their own messages to the system log,
+e.g., to mark the start and end of a test run.  Messages are handed to
+the local syslog daemon as if generated on the device: they are time
+stamped on arrival and follow the same filtering and forwarding rules
+as any other message.  So where a message ends up, a log file, a remote
+server, or both, is decided by the syslog configuration, not the
+caller.
+
+From the CLI, the admin-exec `log` command takes the message text, with
+optional `severity`, `facility`, and `msgid` keywords before it:
+
+<pre class="cli"><code>admin@example:/> <b>log Kilroy was here</b>
+admin@example:/> <b>log severity warning facility daemon msgid test-start Test 42 starting</b>
+admin@example:/> <b>show log tail 2</b>
+Sep 15 15:29:01 example admin: Kilroy was here
+Sep 15 15:29:07 example admin: Test 42 starting
+</code></pre>
+
+Over NETCONF and RESTCONF the same operation is available as the
+`infix-syslog:log` RPC, which also exposes RFC 5424 structured data:
+
+```bash
+~$ curl -k -u admin:admin -X POST \
+     -H "Content-Type: application/yang-data+json" \
+     https://example.local/restconf/operations/infix-syslog:log \
+     -d '{"infix-syslog:input": {
+            "message": "Test 42 starting",
+            "severity": "warning",
+            "facility": "ietf-syslog:daemon",
+            "app-name": "infamy",
+            "msgid": "test-start",
+            "structured-data": [{
+              "id": "test@32473",
+              "param": [{"name": "name", "value": "syslog/rpc_log"}]
+            }]
+          }}'
+```
+
+| **Field**         | **Default**  | **Description**                                              |
+|-------------------|--------------|--------------------------------------------------------------|
+| `message`         | *mandatory*  | Free-form message text                                       |
+| `severity`        | `notice`     | Same levels as in the facility filters, `emergency`..`debug` |
+| `facility`        | `user`       | Any facility from the table at the end of this document      |
+| `app-name`        | calling user | RFC 5424 APP-NAME, shown as the tag in log files             |
+| `msgid`           | none         | RFC 5424 MSGID, e.g., `test-start`                           |
+| `structured-data` | none         | RFC 5424 SD elements, each an `id` with `name`/`value` params |
+
+In an [RFC5424][] formatted log file the message above is logged as:
+
+```
+2026-09-15T15:29:07.123456+02:00 example infamy - test-start [test@32473 name="syslog/rpc_log"] Test 42 starting
+```
+
+The `msgid` property filter, see [Property-Based Filtering](#property-based-filtering),
+can be used to route such messages to a dedicated log file.
+
 ## Log to Remote Server
 
 Logging to a remote syslog server is the recommended way of supervising

package/confd/confd.mk

@@ -10,7 +10,7 @@ CONFD_SITE = $(BR2_EXTERNAL_INFIX_PATH)/src/confd
 CONFD_LICENSE = BSD-3-Clause
 CONFD_LICENSE_FILES = LICENSE
 CONFD_REDISTRIBUTE = NO
-CONFD_DEPENDENCIES = host-sysrepo sysrepo rousette netopeer2 jansson libite sysrepo libsrx libglib2 libev
+CONFD_DEPENDENCIES = host-sysrepo sysrepo rousette netopeer2 jansson libite sysrepo libsrx libglib2 libev sysklogd
 CONFD_AUTORECONF = YES
 CONFD_CONF_OPTS += --disable-silent-rules --with-crypt=$(BR2_PACKAGE_CONFD_DEFAULT_CRYPT)
 CONFD_SYSREPO_SHM_PREFIX = sr_buildroot$(subst /,_,$(CONFIG_DIR))_confd

src/bin/copy.c

@@ -12,6 +12,7 @@
 #include <sys/types.h>
 #include <sys/wait.h>
 
+#include <libyang/libyang.h>
 #include <sysrepo.h>
 #include <sysrepo/netconf_acm.h>
 #include <sysrepo/values.h>
@@ -341,6 +342,9 @@ static int sysrepo_init(sr_conn_ctx_t **conn, sr_session_ctx_t **sess,
 		goto fail;
 	}
 
+	/* Like klish-plugin-sysrepo, lets RPC callbacks see who called */
+	sr_session_set_orig_name(*sess, user);
+
 	return SR_ERR_OK;
 fail:
 	sysrepo_print_error(*sess);
@@ -859,7 +863,7 @@ static int usage_rpc(int rc)
 	       "Arguments:\n"
 	       "  rpc-xpath          RPC XPath (e.g., /ietf-system:set-current-datetime)\n"
 	       "  key value          Pairs of RPC argument names and values\n"
-	       "                     Values can be comma-separated for lists/leaf-lists\n"
+	       "                     Leaf-list values can be comma-separated\n"
 	       "\n"
 	       "Examples:\n"
 	       "  %s /ietf-system:set-current-datetime current-datetime \"2025-01-01T00:00:00Z\"\n"
@@ -870,6 +874,22 @@ static int usage_rpc(int rc)
 	return rc;
 }
 
+static bool is_leaflist(sr_conn_ctx_t *conn, const char *rpc_xpath, const char *key)
+{
+	char xpath[strlen(rpc_xpath) + strlen(key) + 2];
+	const struct lysc_node *node;
+	const struct ly_ctx *ctx;
+	bool rc;
+
+	snprintf(xpath, sizeof(xpath), "%s/%s", rpc_xpath, key);
+	ctx = sr_acquire_context(conn);
+	node = lys_find_path(ctx, NULL, xpath, 0);
+	rc = node && node->nodetype == LYS_LEAFLIST;
+	sr_release_context(conn);
+
+	return rc;
+}
+
 /* Execute RPC from CLI arguments: xpath and key-value pairs */
 static int rpc_exec(const char *rpc_xpath, int argc, char *argv[])
 {
@@ -892,8 +912,8 @@ static int rpc_exec(const char *rpc_xpath, int argc, char *argv[])
 		const char *val = argv[i + 1];
 		char *val_copy, *token, *saveptr;
 
-		/* Check if value contains commas - split into multiple values */
-		if (strchr(val, ',')) {
+		/* Comma-separated values are only a list for leaf-lists */
+		if (strchr(val, ',') && is_leaflist(conn, rpc_xpath, key)) {
 			val_copy = strdup(val);
 			if (!val_copy) {
 				warnx("Memory allocation failed");

src/confd/configure.ac

@@ -110,6 +110,7 @@ PKG_CHECK_MODULES([libite],  [libite >= 2.6.1])
 PKG_CHECK_MODULES([sysrepo], [sysrepo >= 4.2.10])
 PKG_CHECK_MODULES([libyang], [libyang >= 4.2.2])
 PKG_CHECK_MODULES([libsrx],  [libsrx >= 1.0.0])
+PKG_CHECK_MODULES([libsyslog], [libsyslog >= 2.7.0])
 PKG_CHECK_MODULES([libcrypto], [libcrypto])
 
 AC_CHECK_HEADER([ev.h],

src/confd/src/Makefile.am

@@ -20,6 +20,7 @@ confd_plugin_la_CFLAGS  =			\
 	$(libcrypto_CFLAGS)			\
 	$(sysrepo_CFLAGS)			\
 	$(libsrx_CFLAGS)			\
+	$(libsyslog_CFLAGS)			\
 	$(CFLAGS)
 
 confd_plugin_la_LIBADD  =			\
@@ -29,7 +30,8 @@ confd_plugin_la_LIBADD  =			\
 	$(libite_LIBS)				\
 	$(libcrypto_LIBS)			\
 	$(sysrepo_LIBS)				\
-	$(libsrx_LIBS)
+	$(libsrx_LIBS)				\
+	$(libsyslog_LIBS)
 
 confd_plugin_la_SOURCES =			\
 	base64.c		base64.h	\

src/confd/src/core.c

@@ -900,6 +900,10 @@ int sr_plugin_init_cb(sr_session_ctx_t *session, void **priv)
 	if (rc)
 		goto err;
 
+	rc = syslog_rpc_init(&confd);
+	if (rc)
+		goto err;
+
 	/* Candidate infer configurations */
 	rc = interfaces_cand_init(&confd);
 	if (rc)

src/confd/src/core.h

@@ -133,6 +133,10 @@ typedef enum {
 	if ((rc = register_rpc(s, x, c, a, u)))			\
 		goto fail
 
+#define REGISTER_RPC_TREE(s,x,c,a,u)				\
+	if ((rc = register_rpc_tree(s, x, c, a, u)))		\
+		goto fail
+
 struct confd {
 	sr_session_ctx_t       *session; /* running datastore */
 	sr_session_ctx_t       *startup; /* startup datastore */
@@ -192,6 +196,15 @@ static inline int register_rpc(sr_session_ctx_t *session, const char *xpath,
 	return rc;
 }
 
+static inline int register_rpc_tree(sr_session_ctx_t *session, const char *xpath,
+	sr_rpc_tree_cb cb, void *arg, sr_subscription_ctx_t **sub)
+{
+	int rc = sr_rpc_subscribe_tree(session, xpath, cb, arg, 0, SR_SUBSCR_NO_THREAD, sub);
+	if (rc)
+		ERROR("failed subscribing to %s rpc: %s", xpath, sr_strerror(rc));
+	return rc;
+}
+
 
 /* core.c */
 int finit_enable(const char *svc);
@@ -211,6 +224,7 @@ int interfaces_cand_init(struct confd *confd);
 
 /* syslog.c */
 int syslog_change(sr_session_ctx_t *session, struct lyd_node *config, struct lyd_node *diff, sr_event_t event, struct confd *confd);
+int syslog_rpc_init(struct confd *confd);
 
 /* system.c */
 int system_rpc_init (struct confd *confd);