logging: runtime setting of syslog server ip address

Added functionality to change the syslog server's
ip address at runtime as well as sample for
syslog network backend

Signed-off-by: David Corbeil <david.corbeil@dynon.com>

include/zephyr/logging/log_backend_net.h

@@ -0,0 +1,34 @@
+/*
+ * Copyright (c) 2023 David Corbeil
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#ifndef ZEPHYR_LOG_BACKEND_NET_H_
+#define ZEPHYR_LOG_BACKEND_NET_H_
+
+#include <stdbool.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief Allows user to set a server IP address at runtime
+ *
+ * @details This function allows the user to set an IPv4 or IPv6 address at runtime. It can be
+ *          called either before or after the backend has been initialized. If it gets called when
+ *          the net logger backend context is running, it'll release it and create another one with
+ *          the new address next time process() gets called.
+ *
+ * @param addr     String that contains the IP address.
+ *
+ * @return True if parsing could be done, false otherwise.
+ */
+bool log_backend_net_set_addr(const char *addr);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* ZEPHYR_LOG_BACKEND_NET_H_ */

samples/net/syslog_net/Kconfig

@@ -12,4 +12,20 @@ config NET_SAMPLE_SEND_ITERATIONS
 	  Send sample data this many times before exiting. A value of
 	  zero means that the defaults in the application are used.
 
+
+config NET_SAMPLE_SERVER_RUNTIME
+	string "Syslog server IP address set at runtime"
+	help
+	  Server address for the syslog server.
+	  This server address gets set at rumtime by the sample
+	  app defore the backend is initialized. This can be
+	  either IPv4 or IPv6 address. Server listen UDP port
+	  number can be configured here too.
+	  Following syntax is supported:
+	  192.0.2.1:514
+	  192.0.2.42
+	  [2001:db8::1]:514
+	  [2001:db8::2]
+	  2001:db::42
+
 source "Kconfig.zephyr"

samples/net/syslog_net/overlay-runtime-srv-addr.conf

@@ -0,0 +1,3 @@
+CONFIG_LOG_BACKEND_NET_SERVER=""
+CONFIG_LOG_BACKEND_NET_AUTOSTART=n
+CONFIG_NET_SAMPLE_SERVER_RUNTIME="192.0.2.2:514"

samples/net/syslog_net/sample.yaml

@@ -31,3 +31,9 @@ tests:
     filter: TOOLCHAIN_HAS_NEWLIB == 1
     extra_configs:
       - CONFIG_LOG_BACKEND_NET_AUTOSTART=n
+  sample.net.syslog.runtime_srv_addr:
+    filter: TOOLCHAIN_HAS_NEWLIB == 1
+    extra_configs:
+      - CONFIG_LOG_BACKEND_NET_AUTOSTART=n
+      - CONFIG_LOG_BACKEND_NET_SERVER=""
+      - CONFIG_NET_SAMPLE_SERVER_RUNTIME="192.0.2.2:514"

samples/net/syslog_net/src/main.c

@@ -10,6 +10,7 @@ LOG_MODULE_REGISTER(net_syslog, LOG_LEVEL_DBG);
 #include <zephyr/kernel.h>
 
 #include <zephyr/logging/log_backend.h>
+#include <zephyr/logging/log_backend_net.h>
 #include <zephyr/logging/log_ctrl.h>
 
 #include <stdlib.h>
@@ -36,6 +37,16 @@ int main(void)
 		const struct log_backend *backend = log_backend_net_get();
 
 		if (!log_backend_is_active(backend)) {
+
+			/* Specifying an address by calling this function will
+			 * override the value given to LOG_BACKEND_NET_SERVER.
+			   It can also be called at any other time after the backend
+			   is started. The net context will be released and
+			   restarted with the newly specified address.
+			 */
+			if (strlen(CONFIG_LOG_BACKEND_NET_SERVER) == 0) {
+				log_backend_net_set_addr(CONFIG_NET_SAMPLE_SERVER_RUNTIME);
+			}
 			log_backend_init(backend);
 			log_backend_enable(backend, backend->cb->ctx, CONFIG_LOG_MAX_LEVEL);
 		}

subsys/logging/backends/log_backend_net.c

@@ -10,6 +10,7 @@ LOG_MODULE_REGISTER(log_backend_net, CONFIG_LOG_DEFAULT_LEVEL);
 #include <zephyr/logging/log_backend.h>
 #include <zephyr/logging/log_core.h>
 #include <zephyr/logging/log_output.h>
+#include <zephyr/logging/log_backend_net.h>
 #include <zephyr/net/net_pkt.h>
 #include <zephyr/net/net_context.h>
 
@@ -196,19 +197,39 @@ static int format_set(const struct log_backend *const backend, uint32_t log_type
 	return 0;
 }
 
-static void init_net(struct log_backend const *const backend)
+bool log_backend_net_set_addr(const char *addr)
 {
-	ARG_UNUSED(backend);
-	int ret;
+	if (net_init_done) {
+		const struct log_backend *backend = log_backend_net_get();
+		/* Release context so it can be recreated with the specified ip address
+		 * next time process() is called
+		 */
+		net_context_put(backend->cb->ctx);
+		net_init_done = false;
+	}
 
 	net_sin(&server_addr)->sin_port = htons(514);
 
-	ret = net_ipaddr_parse(CONFIG_LOG_BACKEND_NET_SERVER,
-			       sizeof(CONFIG_LOG_BACKEND_NET_SERVER) - 1,
-			       &server_addr);
-	if (ret == 0) {
-		LOG_ERR("Cannot configure syslog server address");
-		return;
+	bool ret = net_ipaddr_parse(addr, strlen(addr), &server_addr);
+
+	if (!ret) {
+		LOG_ERR("Cannot parse syslog server address");
+		return ret;
+	}
+
+	return ret;
+}
+
+static void init_net(struct log_backend const *const backend)
+{
+	ARG_UNUSED(backend);
+
+	if (strlen(CONFIG_LOG_BACKEND_NET_SERVER) != 0) {
+		bool ret = log_backend_net_set_addr(CONFIG_LOG_BACKEND_NET_SERVER);
+
+		if (!ret) {
+			return;
+		}
 	}
 
 	log_backend_deactivate(log_backend_net_get());