From: David Härdeman <david@hardeman.nu>
Date: Wed, 8 Oct 2025 05:44:56 +0000 (+0200)
Subject: odhcpd: support stderr logging
X-Git-Url: http://git.openwrt.org/?a=commitdiff_plain;h=e2ecf7ba6d72a9b66d4a3b59fdabef9885d43949;p=project%2Fodhcpd.git

odhcpd: support stderr logging

This is just for debugging purposes. Also, make sure that a cmdline loglevel
doesn't get overwritten by what's in the cfg file (it's customary that
command-line options take precedence over configuration file settings).

Signed-off-by: David Härdeman <david@hardeman.nu>
Link: https://github.com/openwrt/odhcpd/pull/273
Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
---

diff --git a/src/config.c b/src/config.c
index 0bcae10..d6573e2 100644
--- a/src/config.c
+++ b/src/config.c
@@ -41,6 +41,8 @@ struct config config = {
 	.ra_piofolder_fd = -1,
 	.uci_cfgfile = "dhcp",
 	.log_level = LOG_WARNING,
+	.log_level_cmdline = false,
+	.log_syslog = true,
 };
 
 #define START_DEFAULT	100
@@ -423,9 +425,11 @@ static void set_config(struct uci_section *s)
 	if ((c = tb[ODHCPD_ATTR_LOGLEVEL])) {
 		int log_level = (blobmsg_get_u32(c) & LOG_PRIMASK);
 
-		if (config.log_level != log_level) {
+		if (config.log_level != log_level && config.log_level_cmdline) {
 			config.log_level = log_level;
-			setlogmask(LOG_UPTO(config.log_level));
+			if (config.log_syslog)
+				setlogmask(LOG_UPTO(config.log_level));
+			notice("Log level set to %d\n", config.log_level);
 		}
 	}
 }
diff --git a/src/odhcpd.c b/src/odhcpd.c
index 6b07f0e..1f3cd1b 100644
--- a/src/odhcpd.c
+++ b/src/odhcpd.c
@@ -74,6 +74,7 @@ static void print_usage(const char *app)
 	       "\n"
 	       "	-c <path>	Use an alternative configuration file\n"
 	       "	-l <int>	Specify log level 0..7 (default %d)\n"
+	       "	-f		Log to stderr instead of syslog\n"
 	       "	-h		Print this help text and exit\n",
 	       app, config.log_level);
 }
@@ -92,10 +93,9 @@ static bool ipv6_enabled(void)
 
 int main(int argc, char **argv)
 {
-	openlog("odhcpd", LOG_PERROR | LOG_PID, LOG_DAEMON);
 	int opt;
 
-	while ((opt = getopt(argc, argv, "c:l:h")) != -1) {
+	while ((opt = getopt(argc, argv, "c:l:fh")) != -1) {
 		switch (opt) {
 		case 'c':
 			config.uci_cfgfile = realpath(optarg, NULL);
@@ -103,14 +103,24 @@ int main(int argc, char **argv)
 			break;
 		case 'l':
 			config.log_level = (atoi(optarg) & LOG_PRIMASK);
+			config.log_level_cmdline = true;
 			fprintf(stderr, "Log level set to %d\n", config.log_level);
 			break;
+		case 'f':
+			config.log_syslog = false;
+			fprintf(stderr, "Logging to stderr\n");
+			break;
 		case 'h':
 			print_usage(argv[0]);
 			return 0;
 		}
 	}
-	setlogmask(LOG_UPTO(config.log_level));
+
+	if (config.log_syslog) {
+		openlog("odhcpd", LOG_PERROR | LOG_PID, LOG_DAEMON);
+		setlogmask(LOG_UPTO(config.log_level));
+	}
+
 	uloop_init();
 
 	if (getuid() != 0) {
diff --git a/src/odhcpd.h b/src/odhcpd.h
index 0cda056..9a41a59 100644
--- a/src/odhcpd.h
+++ b/src/odhcpd.h
@@ -69,10 +69,14 @@ struct nl_sock;
 extern struct vlist_tree leases;
 extern struct config config;
 
-#define __iflog(lvl, fmt, ...)						\
-	do {								\
-		if (lvl <= config.log_level)				\
-			syslog(lvl, fmt __VA_OPT__(, ) __VA_ARGS__);	\
+#define __iflog(lvl, fmt, ...)							\
+	do {									\
+		if (lvl > config.log_level)					\
+			break;							\
+		if (config.log_syslog)						\
+			syslog(lvl, fmt __VA_OPT__(, ) __VA_ARGS__);		\
+		else								\
+			fprintf(stderr, fmt "\n" __VA_OPT__(, ) __VA_ARGS__);	\
 	} while(0)
 
 #define debug(fmt, ...)     __iflog(LOG_DEBUG, fmt __VA_OPT__(, ) __VA_ARGS__)
@@ -194,6 +198,8 @@ struct config {
 
 	char *uci_cfgfile;
 	int log_level;
+	bool log_level_cmdline;
+	bool log_syslog;
 };
 
 /* 2-byte type + 128-byte DUID, RFC8415, §11.1 */