Add option to skip message with certain syslog level

Author: cgzones

README.md

@@ -108,6 +108,9 @@ Optional settings
     ExcludeSyslogFacility=
         A list of strings. Specifies the syslog facilities to skip forwarding. Possible values are: "kern", "user", "mail", "daemon", "auth", "syslog", "lpr", "news", "uucp", "cron", "authpriv", "ftp", "ntp", "security", "console", "solaris-cron", "local0", "local1", "local2", "local3", "local4", "local5", "local6" and "local7".
 
+    ExcludeSyslogLevel=
+        A list of strings. Specifies the syslog levels to skip forwarding. Possible values are: "emerg", "alert", "crit", "err", "warning", "notice", "info" and "debug".
+
 **EXAMPLE**
 
  Example 1.UDP Multicast
@@ -149,14 +152,15 @@ UseSysLogStructuredData=yes
 UseSysLogMsgId=yes
 ```
 
-Example 5. Skipping messages with facility AUTH or AUTHPRIV
+Example 5. Skipping messages with facility AUTH or AUTHPRIV and messages with level DEBUG
 
 ``` toml
 [Network]
 Address=192.168.8.101:514
 #Protocol=udp
 LogFormat=rfc3339
 ExcludeSyslogFacility=auth authpriv
+ExcludeSyslogLevel=debug
 ```
 
 Example 6. TLS with certificate authentocation mode

conf/netlogd.conf.in

@@ -17,3 +17,4 @@
 #NoDelay=no
 #SendBuffer=
 #ExcludeSyslogFacility=
+#ExcludeSyslogLevel=

src/netlog/netlog-conf.c

@@ -240,6 +240,48 @@ int config_parse_syslog_facility(const char *unit,
         return 0;
 }
 
+int config_parse_syslog_level(const char *unit,
+                              const char *filename,
+                              unsigned line,
+                              const char *section,
+                              unsigned section_line,
+                              const char *lvalue,
+                              int ltype,
+                              const char *rvalue,
+                              void *data,
+                              void *userdata) {
+        Manager *m = userdata;
+        uint8_t val = 0;
+        int r;
+
+        assert(filename);
+        assert(lvalue);
+        assert(rvalue);
+        assert(data);
+        assert(m);
+
+        for (const char *p = rvalue;;) {
+                _cleanup_free_ char *word = NULL;
+
+                r = extract_first_word(&p, &word, NULL, EXTRACT_QUOTES|EXTRACT_RELAX);
+                if (r < 0) {
+                        log_syntax(unit, LOG_WARNING, filename, line, r, "Failed to parse %s= specifier '%s', ignoring: %m", lvalue, rvalue);
+                        return 0;
+                }
+                if (r == 0)
+                        break;
+
+                r = syslog_level_from_string(word);
+                if (r < 0) {
+                        log_syntax(unit, LOG_WARNING, filename, line, r, "Failed to parse syslog level '%s', ignoring", word);
+                } else
+                        val |= UINT8_C(1) << r;
+        }
+
+        m->excluded_syslog_levels = val;
+        return 0;
+}
+
 int manager_parse_config_file(Manager *m) {
         int r;
 

src/netlog/netlog-conf.h

@@ -73,4 +73,15 @@ int config_parse_syslog_facility(const char *unit,
                                  void *data,
                                  void *userdata);
 
+int config_parse_syslog_level(const char *unit,
+                              const char *filename,
+                              unsigned line,
+                              const char *section,
+                              unsigned section_line,
+                              const char *lvalue,
+                              int ltype,
+                              const char *rvalue,
+                              void *data,
+                              void *userdata);
+
 int manager_parse_config_file(Manager *m);

src/netlog/netlog-gperf.gperf

@@ -33,3 +33,4 @@ Network.KeepAliveProbes,          config_parse_unsigned,                  0, off
 Network.NoDelay,                  config_parse_bool,                      0, offsetof(Manager, no_delay)
 Network.SendBuffer,               config_parse_iec_size,                  0, offsetof(Manager, send_buffer)
 Network.ExcludeSyslogFacility,    config_parse_syslog_facility,           0, offsetof(Manager, excluded_syslog_facilities)
+Network.ExcludeSyslogLevel,       config_parse_syslog_level,              0, offsetof(Manager, excluded_syslog_levels)

src/netlog/netlog-manager.c

@@ -73,6 +73,19 @@ static const char *const syslog_facility_table[_SYSLOG_FACILITY_MAX] = {
 
 DEFINE_STRING_TABLE_LOOKUP(syslog_facility, SysLogFacility);
 
+static const char *const syslog_level_table[_SYSLOG_LEVEL_MAX] = {
+        [SYSLOG_LEVEL_EMERGENCY]     = "emerg",
+        [SYSLOG_LEVEL_ALERT]         = "alert",
+        [SYSLOG_LEVEL_CRITICAL]      = "crit",
+        [SYSLOG_LEVEL_ERROR]         = "err",
+        [SYSLOG_LEVEL_WARNING]       = "warning",
+        [SYSLOG_LEVEL_NOTICE]        = "notice",
+        [SYSLOG_LEVEL_INFORMATIONAL] = "info",
+        [SYSLOG_LEVEL_DEBUG]         = "debug",
+};
+
+DEFINE_STRING_TABLE_LOOKUP(syslog_level, SysLogLevel);
+
 typedef struct ParseFieldVec {
         const char *field;
         size_t field_len;
@@ -222,6 +235,10 @@ static int manager_read_journal_input(Manager *m) {
                 r = safe_atou(priority, &sev);
                 if (r < 0)
                         log_debug("Failed to parse syslog priority: %s", priority);
+                else if (sev < _SYSLOG_LEVEL_MAX && ((UINT8_C(1) << sev) & m->excluded_syslog_levels)) {
+                        log_debug("Skipping message with excluded syslog level %s.", syslog_level_to_string(sev));
+                        return 0;
+                }
 
                 if (sev > LOG_DEBUG)
                         sev = JOURNAL_DEFAULT_SEVERITY;

src/netlog/netlog-manager.h

@@ -59,6 +59,20 @@ typedef enum SysLogFacility {
         _SYSLOG_FACILITY_INVALID     = -EINVAL,
 } SysLogFacility;
 
+/* RFC 5424 Section 6.2.1 */
+typedef enum SysLogLevel {
+        SYSLOG_LEVEL_EMERGENCY     = 0,
+        SYSLOG_LEVEL_ALERT         = 1,
+        SYSLOG_LEVEL_CRITICAL      = 2,
+        SYSLOG_LEVEL_ERROR         = 3,
+        SYSLOG_LEVEL_WARNING       = 4,
+        SYSLOG_LEVEL_NOTICE        = 5,
+        SYSLOG_LEVEL_INFORMATIONAL = 6,
+        SYSLOG_LEVEL_DEBUG         = 7,
+        _SYSLOG_LEVEL_MAX,
+        _SYSLOG_LEVEL_INVALID      = -EINVAL,
+} SysLogLevel;
+
 typedef struct Manager Manager;
 
 struct Manager {
@@ -89,6 +103,7 @@ struct Manager {
         char *server_name;
 
         uint32_t excluded_syslog_facilities;
+        uint8_t excluded_syslog_levels;
 
         /* journal  */
         int journal_watch_fd;
@@ -159,3 +174,6 @@ int log_format_from_string(const char *s) _pure_;
 
 const char *syslog_facility_to_string(SysLogFacility v) _const_;
 SysLogFacility syslog_facility_from_string(const char *s) _pure_;
+
+const char *syslog_level_to_string(SysLogLevel v) _const_;
+SysLogLevel syslog_level_from_string(const char *s) _pure_;