From 0d776d39bbdea4bceff3c849ca87fd33db25ac14 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Fin=20Maa=C3=9F?= <f.maass@vogl-electronic.com>
Date: Thu, 22 Feb 2024 10:08:53 +0100
Subject: [PATCH] net: dhcpv4: set log backend net ip via option
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Adds the option to set the log_backend_net ip via dhcpv4
option 7.

Signed-off-by: Fin Maaß <f.maass@vogl-electronic.com>
---
 subsys/logging/backends/Kconfig.net     |  7 +++++
 subsys/net/lib/dhcpv4/dhcpv4.c          | 40 +++++++++++++++++++++++++
 subsys/net/lib/dhcpv4/dhcpv4_internal.h |  1 +
 3 files changed, 48 insertions(+)

diff --git a/subsys/logging/backends/Kconfig.net b/subsys/logging/backends/Kconfig.net
index 36a5096235b..91de9074324 100644
--- a/subsys/logging/backends/Kconfig.net
+++ b/subsys/logging/backends/Kconfig.net
@@ -49,6 +49,13 @@ config LOG_BACKEND_NET_AUTOSTART
 	  started by the application later on. Otherwise the logging
 	  thread might block.
 
+config LOG_BACKEND_NET_USE_DHCPV4_OPTION
+	bool "Use DHCPv4 Log Server Option to configure syslog server"
+	depends on NET_DHCPV4
+	help
+	  When enabled the syslog server IP address is read from the DHCPv4
+	  Log Server Option (7).
+
 backend = NET
 backend-str = net
 source "subsys/logging/Kconfig.template.log_format_config"
diff --git a/subsys/net/lib/dhcpv4/dhcpv4.c b/subsys/net/lib/dhcpv4/dhcpv4.c
index 0cf133e6d74..25f84b04e57 100644
--- a/subsys/net/lib/dhcpv4/dhcpv4.c
+++ b/subsys/net/lib/dhcpv4/dhcpv4.c
@@ -28,6 +28,10 @@ LOG_MODULE_REGISTER(net_dhcpv4, CONFIG_NET_DHCPV4_LOG_LEVEL);
 #include <zephyr/net/dhcpv4.h>
 #include <zephyr/net/dns_resolve.h>
 
+#include <zephyr/logging/log_backend.h>
+#include <zephyr/logging/log_backend_net.h>
+#include <zephyr/logging/log_ctrl.h>
+
 #include "dhcpv4_internal.h"
 #include "ipv4.h"
 #include "net_stats.h"
@@ -56,6 +60,9 @@ static sys_slist_t option_vendor_callbacks = SYS_SLIST_STATIC_INIT(&option_vendo
 static const uint8_t min_req_options[] = {
 	DHCPV4_OPTIONS_SUBNET_MASK,
 	DHCPV4_OPTIONS_ROUTER,
+#ifdef CONFIG_LOG_BACKEND_NET_USE_DHCPV4_OPTION
+	DHCPV4_OPTIONS_LOG_SERVER,
+#endif
 #ifdef CONFIG_NET_DHCPV4_OPTION_NTP_SERVER
 	DHCPV4_OPTIONS_NTP_SERVER,
 #endif
@@ -969,6 +976,39 @@ static bool dhcpv4_parse_options(struct net_pkt *pkt,
 			break;
 		}
 #endif
+#if defined(CONFIG_LOG_BACKEND_NET_USE_DHCPV4_OPTION)
+		case DHCPV4_OPTIONS_LOG_SERVER: {
+			struct sockaddr_in log_server = { 0 };
+
+			/* Log server option may present 1 or more
+			 * addresses. Each 4 bytes in length. Log
+			 * servers should be listed in order
+			 * of preference.  Hence we choose the first
+			 * and skip the rest.
+			 */
+			if (length % 4 != 0U) {
+				NET_ERR("options_log_server, bad length");
+				return false;
+			}
+
+			if (net_pkt_read(pkt, log_server.sin_addr.s4_addr, 4) < 0 ||
+			    net_pkt_skip(pkt, length - 4U) < 0) {
+				NET_ERR("options_log_server, short packet");
+				return false;
+			}
+
+			log_server.sin_family = AF_INET;
+			log_backend_net_set_ip((struct sockaddr *)&log_server);
+
+#ifdef CONFIG_LOG_BACKEND_NET_AUTOSTART
+			log_backend_net_start();
+#endif
+
+			NET_DBG("options_log_server: %s", net_sprint_ipv4_addr(&log_server));
+
+			break;
+		}
+#endif /* CONFIG_LOG_BACKEND_NET_USE_DHCPV4_OPTION */
 #if defined(CONFIG_NET_DHCPV4_OPTION_NTP_SERVER)
 		case DHCPV4_OPTIONS_NTP_SERVER: {
 
diff --git a/subsys/net/lib/dhcpv4/dhcpv4_internal.h b/subsys/net/lib/dhcpv4/dhcpv4_internal.h
index 69b31ed7c07..77b4087bd0e 100644
--- a/subsys/net/lib/dhcpv4/dhcpv4_internal.h
+++ b/subsys/net/lib/dhcpv4/dhcpv4_internal.h
@@ -54,6 +54,7 @@ struct dhcp_msg {
 #define DHCPV4_OPTIONS_SUBNET_MASK	1
 #define DHCPV4_OPTIONS_ROUTER		3
 #define DHCPV4_OPTIONS_DNS_SERVER	6
+#define DHCPV4_OPTIONS_LOG_SERVER	7
 #define DHCPV4_OPTIONS_HOST_NAME	12
 #define DHCPV4_OPTIONS_NTP_SERVER	42
 #define DHCPV4_OPTIONS_VENDOR_SPECIFIC	43