From 030df8b715d2f8bf5bb33d389c503ed49e09d9ad Mon Sep 17 00:00:00 2001
From: Thomas Basler <thomas@familie-basler.net>
Date: Sat, 19 Apr 2025 15:14:12 +0200
Subject: [PATCH] Syslog: Send dynamic headers based on log level of the
 message

The code part regarding overflow was also removed as the write method 1 in any case. Different handling regarding line break etc. in one message was also removed as the function is called only containing one log line from MessageOutput.
---
 include/SyslogLogger.h |  1 +
 src/SyslogLogger.cpp   | 38 ++++++++++++++++++++++++++++----------
 2 files changed, 29 insertions(+), 10 deletions(-)

diff --git a/include/SyslogLogger.h b/include/SyslogLogger.h
index a6982e7b..f38f3730 100644
--- a/include/SyslogLogger.h
+++ b/include/SyslogLogger.h
@@ -19,6 +19,7 @@ private:
     bool isResolved() const {
         return _address != INADDR_NONE;
     }
+    static uint8_t calculatePrival(uint8_t facility, char errorCode);
 
     Task _loopTask;
     std::mutex _mutex;
diff --git a/src/SyslogLogger.cpp b/src/SyslogLogger.cpp
index df5251e0..b8223fcc 100644
--- a/src/SyslogLogger.cpp
+++ b/src/SyslogLogger.cpp
@@ -47,7 +47,7 @@ void SyslogLogger::updateSettings(const String&& hostname)
 
     ESP_LOGI(TAG, "Logging to %s!", _syslog_hostname.c_str());
 
-    _header = "<14>1 - ";  // RFC5424: Facility USER, severity INFO, version 1, NIL timestamp.
+    _header = ">1 - ";  // RFC5424: Facility USER, severity INFO, version 1, NIL timestamp.
     _header += hostname;
     _header += " OpenDTU ";
     _header += _proc_id;
@@ -64,19 +64,22 @@ void SyslogLogger::write(const uint8_t *buffer, size_t size)
     if (!_enabled || !isResolved()) {
         return;
     }
+
+    String header = "<";
+    header += String(calculatePrival(1, buffer[0]));
+
+    _udp.beginPacket(_address, _port);
+    _udp.print(header);
+    _udp.print(_header);
+
     for (int i = 0; i < size; i++) {
         uint8_t c = buffer[i];
-        bool overflow = false;
         if (c != '\r' && c != '\n') {
             // Replace control and non-ASCII characters with '?'.
-            overflow = !_udp.write(c >= 0x20 && c < 0x7f ? c : '?');
-        }
-        if (c == '\n' || overflow) {
-            _udp.endPacket();
-            _udp.beginPacket(_address, _port);
-            _udp.print(_header);
+            _udp.write(c >= 0x20 && c < 0x7f ? c : '?');
         }
     }
+    _udp.endPacket();
 }
 
 void SyslogLogger::disable()
@@ -117,11 +120,26 @@ bool SyslogLogger::resolveAndStart()
         }
         _address = _udp.remoteIP();  // Store resolved address.
     }
-    _udp.beginPacket(_address, _port);
-    _udp.print(_header);
     return true;
 }
 
+uint8_t SyslogLogger::calculatePrival(uint8_t facility, char errorCode)
+{
+    // ESP LOG ID's are two ahead of syslog ID's
+    // e.g. ESP_LOG_ERROR (1) = Syslog ERROR 3
+    if (errorCode == 'E') {
+        return facility * 8 + ESP_LOG_ERROR + 2;
+    } else if (errorCode == 'W') {
+        return facility * 8 + ESP_LOG_WARN + 2;
+    } else if (errorCode == 'D') {
+        return facility * 8 + ESP_LOG_DEBUG + 2;
+    } else if (errorCode == 'V') {
+        return facility * 8 + ESP_LOG_VERBOSE + 2;
+    }
+
+    return facility * 8 + ESP_LOG_INFO + 2;
+}
+
 void SyslogLogger::loop()
 {
     std::lock_guard<std::mutex> lock(_mutex);