shared: add nm_utils_syslog_coerce_from_nm() util

When a VPN plugin logs to syslog(), it should not use the syslog
levels that were passed in by NetworkManager directly. Instead,
it must map LOG_NOTICE to LOG_INFO and LOG_INFO to LOG_DEBUG.

Add a utility function does gets that right.

1 files changed, 32 insertions, 0 deletions

diff --git a/shared/nm-utils/nm-vpn-plugin-macros.h b/shared/nm-utils/nm-vpn-plugin-macros.h
index 06f5b28663..acc549f2f3 100644
--- a/shared/nm-utils/nm-vpn-plugin-macros.h
+++ b/shared/nm-utils/nm-vpn-plugin-macros.h
@@ -24,6 +24,38 @@
 
 #include <syslog.h>
 
+static inline int
+nm_utils_syslog_coerce_from_nm (int syslog_level)
+{
+	/* NetworkManager uses internally NMLogLevel levels. When spawning
+	 * the VPN plugin, it maps those levels to syslog levels as follows:
+	 *
+	 *  LOGL_INFO = LOG_NOTICE,
+	 *  LOGL_DEBUG = LOG_INFO,
+	 *  LOGL_TRACE = LOG_DEBUG,
+	 *
+	 * However, when actually printing to syslog, we don't want to print messages
+	 * with LOGL_INFO level as LOG_NOTICE, because they are *not* to be highlighted.
+	 *
+	 * In other words: NetworkManager has 3 levels that should not require highlighting:
+	 * LOGL_INFO, LOGL_DEBUG, LOGL_TRACE. syslog on the other hand has only LOG_INFO and LOG_DEBUG.
+	 *
+	 * So, coerce those values before printing to syslog. When you receive the syslog_level
+	 * from NetworkManager, instead of calling
+	 *   syslog(syslog_level, ...)
+	 * you should call
+	 *   syslog(nm_utils_syslog_coerce_from_nm(syslog_level), ...)
+	 */
+	switch (syslog_level) {
+	case LOG_INFO:
+		return LOG_DEBUG;
+	case LOG_NOTICE:
+		return LOG_INFO;
+	default:
+		return syslog_level;
+	}
+}
+
 static inline const char *
 nm_utils_syslog_to_str (int syslog_level)
 {