Enable configuration of RFC 5424 timestamp fractional digits (#237 cl…

…oses #224)
luigiberrettini · Jun 14, 2020 · 7e0a921 · 7e0a921
1 parent e3d8814
commit 7e0a921
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Showing 4 changed files with 40 additions and 2 deletions.
diff --git a/README.md b/README.md
@@ -111,6 +111,7 @@ The maximum length of a message is detailed in many RFCs that can be summarized
   * `hostname` ([Layout](http://github.com/NLog/NLog/wiki/Layouts)) - the HOSTNAME field of the HEADER part (default: the hostname of the computer that is creating the message)
   * `tag` ([Layout](http://github.com/NLog/NLog/wiki/Layouts)) - the TAG field of the MSG part (default: the name of the assembly that is creating the message)
 * `rfc5424` - settings related to RFC 5424:
+  * `timestampFractionalDigits` - the number of fractional digits for the TIMESTAMP field of the HEADER part (default: 6, max: 16 as per ISO 8601 but since .NET is limited to 7 the other digits will be zeroed)
   * `hostname` ([Layout](http://github.com/NLog/NLog/wiki/Layouts)) - the HOSTNAME field of the HEADER part (default: the hostname of the computer that is creating the message)
   * `appName` ([Layout](http://github.com/NLog/NLog/wiki/Layouts)) - the APPNAME field of the HEADER part (default: the name of the assembly that is creating the message)
   * `procId` ([Layout](http://github.com/NLog/NLog/wiki/Layouts)) - the PROCID field of the HEADER part (default: `-`)

diff --git a/src/NLog.Targets.Syslog.Schema/NLog.Targets.Syslog.xsd b/src/NLog.Targets.Syslog.Schema/NLog.Targets.Syslog.xsd
@@ -85,6 +85,7 @@
                                 <xs:element name="rfc5424" minOccurs="0" maxOccurs="1">
                                     <xs:complexType>
                                         <xs:choice minOccurs="0" maxOccurs="unbounded">
+                                            <xs:element name="timestampFractionalDigits" type="xs:integer" minOccurs="0" maxOccurs="1" />
                                             <xs:element name="hostname" type="nlog:Layout" minOccurs="0" maxOccurs="1" />
                                             <xs:element name="appName" type="nlog:Layout" minOccurs="0" maxOccurs="1" />
                                             <xs:element name="procId" type="nlog:Layout" minOccurs="0" maxOccurs="1" />
@@ -115,6 +116,7 @@
                                             </xs:element>
                                             <xs:element name="disableBom" type="xs:boolean" minOccurs="0" maxOccurs="1" />
                                         </xs:choice>
+                                        <xs:attribute name="timestampFractionalDigits" type="xs:integer" />
                                         <xs:attribute name="hostname" type="nlog:SimpleLayoutAttribute" />
                                         <xs:attribute name="appName" type="nlog:SimpleLayoutAttribute" />
                                         <xs:attribute name="procId" type="nlog:SimpleLayoutAttribute" />

diff --git a/src/NLog.Targets.Syslog/MessageCreation/Rfc5424.cs b/src/NLog.Targets.Syslog/MessageCreation/Rfc5424.cs
@@ -1,6 +1,7 @@
 // Licensed under the BSD license
 // See the LICENSE file in the project root for more information
 
+using System;
 using NLog.Layouts;
 using NLog.Targets.Syslog.Policies;
 using System.Globalization;
@@ -12,10 +13,13 @@ namespace NLog.Targets.Syslog.MessageCreation
 {
     internal class Rfc5424 : MessageBuilder
     {
-        private const string TimestampFormat = "{0:yyyy-MM-ddTHH:mm:ss.ffffffK}";
+        private const string BaseTimestampFormat = "yyyy-MM-ddTHH:mm:ss";
+        private const int Iso8601MaxTimestampFractionalDigits = 16;
+        private const int DotNetDateTimeMaxFractionalDigits = 7;
         private static readonly byte[] SpaceBytes = { 0x20 };
 
         private readonly string version;
+        private readonly string timestampFormat;
         private readonly Layout hostnameLayout;
         private readonly Layout appNameLayout;
         private readonly Layout procIdLayout;
@@ -31,6 +35,7 @@ internal class Rfc5424 : MessageBuilder
         public Rfc5424(Facility facility, LogLevelSeverityConfig logLevelSeverityConfig, Rfc5424Config rfc5424Config, EnforcementConfig enforcementConfig) : base(facility, logLevelSeverityConfig, enforcementConfig)
         {
             version = rfc5424Config.Version;
+            timestampFormat = $"{{0:{TimestampFormat(rfc5424Config.TimestampFractionalDigits)}}}";
             hostnameLayout = rfc5424Config.Hostname;
             appNameLayout = rfc5424Config.AppName;
             procIdLayout = rfc5424Config.ProcId;
@@ -55,9 +60,29 @@ protected override void PrepareMessage(ByteArray buffer, LogEventInfo logEvent,
             utf8MessagePolicy.Apply(buffer);
         }
 
+        private static StringBuilder TimestampFormat(int fractionalDigits)
+        {
+            // BaseTimestampFormat.Length + 1 decimal point + 1 K + Iso8601MaxTimestampFractionalDigits
+            var maxTimestampFormatLength = BaseTimestampFormat.Length + 2 + Iso8601MaxTimestampFractionalDigits;
+            var formatSb = new StringBuilder(BaseTimestampFormat, maxTimestampFormatLength);
+
+            if (fractionalDigits <= 0)
+                return formatSb.Append("K");
+
+            var fRepeatCount = Math.Min(fractionalDigits, DotNetDateTimeMaxFractionalDigits);
+            var requestedMinusDotNet = fractionalDigits - DotNetDateTimeMaxFractionalDigits;
+            const int isoMinusDotNet = Iso8601MaxTimestampFractionalDigits - DotNetDateTimeMaxFractionalDigits;
+            var zeroRepeatCount = Math.Max(0, Math.Min(requestedMinusDotNet, isoMinusDotNet));
+            return formatSb
+                .Append('.')
+                .Append('f', fRepeatCount)
+                .Append('0', Math.Max(0, zeroRepeatCount))
+                .Append("K");
+        }
+
         private void AppendHeader(ByteArray buffer, string pri, LogEventInfo logEvent)
         {
-            var timestamp = string.Format(CultureInfo.InvariantCulture, TimestampFormat, logEvent.TimeStamp);
+            var timestamp = string.Format(CultureInfo.InvariantCulture, timestampFormat, logEvent.TimeStamp);
             var hostname = hostnamePolicySet.Apply(hostnameLayout.Render(logEvent));
             var appName = appNamePolicySet.Apply(appNameLayout.Render(logEvent));
             var procId = procIdPolicySet.Apply(procIdLayout.Render(logEvent));

diff --git a/src/NLog.Targets.Syslog/Settings/Rfc5424Config.cs b/src/NLog.Targets.Syslog/Settings/Rfc5424Config.cs
@@ -18,7 +18,9 @@ namespace NLog.Targets.Syslog.Settings
     public class Rfc5424Config : NotifyPropertyChanged, IDisposable
     {
         private const string DefaultVersion = "1";
+        private const int DefaultTimestampFractionalDigits = 6;
         private const string NilValue = "-";
+        private int timestampFractionalDigits;
         private Layout hostname;
         private Layout appName;
         private Layout procId;
@@ -30,6 +32,13 @@ public class Rfc5424Config : NotifyPropertyChanged, IDisposable
         /// <summary>The VERSION field of the HEADER part</summary>
         public string Version { get; }
 
+        /// <summary>The number of fractional digits for the TIMESTAMP field of the HEADER part</summary>
+        public int TimestampFractionalDigits
+        {
+            get => timestampFractionalDigits;
+            set => SetProperty(ref timestampFractionalDigits, value);
+        }
+
         /// <summary>The default HOSTNAME if no value is provided</summary>
         public string DefaultHostname { get; }
 
@@ -83,6 +92,7 @@ public bool DisableBom
         public Rfc5424Config()
         {
             Version = DefaultVersion;
+            TimestampFractionalDigits = DefaultTimestampFractionalDigits;
             DefaultHostname = HostFqdn();
             hostname = DefaultHostname;
             DefaultAppName = UniversalAssembly.EntryAssembly().Name();