Improve null safety

Author: veniware

Protest/Database/ContactsJsonConverter.cs

@@ -44,13 +44,13 @@ public override void Write(Utf8JsonWriter writer, Database value, JsonSerializer
 
             writer.WriteStartObject();
 
-            if (title?.value.Length > 0)      writer.WriteString(_title, title?.value ?? String.Empty);
+            if (title?.value?.Length > 0)      writer.WriteString(_title, title?.value ?? String.Empty);
             if (name?.Length > 0)             writer.WriteString(_name, name);
-            if (department?.value.Length > 0) writer.WriteString(_department, department?.value ?? String.Empty);
+            if (department?.value?.Length > 0) writer.WriteString(_department, department?.value ?? String.Empty);
 
-            if (email?.value.Length > 0)           writer.WriteString(_email, email?.value ?? String.Empty);
-            if (telephoneNumber?.value.Length > 0) writer.WriteString(_telephone, telephoneNumber?.value ?? String.Empty);
-            if (mobileNumber?.value.Length > 0)    writer.WriteString(_mobile, mobileNumber?.value ?? String.Empty);
+            if (email?.value?.Length > 0)           writer.WriteString(_email, email?.value ?? String.Empty);
+            if (telephoneNumber?.value?.Length > 0) writer.WriteString(_telephone, telephoneNumber?.value ?? String.Empty);
+            if (mobileNumber?.value?.Length > 0)    writer.WriteString(_mobile, mobileNumber?.value ?? String.Empty);
 
             writer.WriteEndObject();
         }

Protest/Protocols/Dhcp.cs

@@ -414,7 +414,7 @@ private static byte[] Request(long timestamp, byte[] transactionId, string mac,
 
         mac = mac.Replace(":", String.Empty);
         mac = mac.Replace("-", String.Empty);
-        if (mac is not null || mac.Length == 12) {
+        if (mac is not null && mac.Length == 12) {
             buffer[index++] = Convert.ToByte(mac[0..2], 16); //client mac address
             buffer[index++] = Convert.ToByte(mac[2..4], 16);
             buffer[index++] = Convert.ToByte(mac[4..6], 16);

Protest/Proxy/TcpReverseProxy.cs

@@ -68,7 +68,7 @@ private async Task ServeClient(TcpClient proxyClient) {
             Interlocked.Increment(ref this.errors);
         }
         finally {
-            proxyClient?.Close();
+            proxyClient.Close();
         }
     }
 

Protest/Tasks/Issues.cs

@@ -17,6 +17,8 @@
 namespace Protest.Tasks;
 
 internal static class Issues {
+    public const long UNIX_BASE_TICKS = 62135596800000;
+
     private const int    MIN_LIFELINE_ENTRIES              = 10;
     private const double WEAK_PASSWORD_ENTROPY_THRESHOLD   = 36.0;
     private const double RTT_STANDARD_DEVIATION_MULTIPLIER = 20.0;
@@ -26,6 +28,7 @@ internal static class Issues {
     private const int DISK_SPACE_THRESHOLD      = 85;
     private const int DISK_IO_THRESHOLD         = 75;
 
+
     public enum SeverityLevel : byte {
         info     = 1,
         warning  = 2,
@@ -132,7 +135,7 @@ public static async void WebSocketHandler(HttpListenerContext ctx) {
 
                 if (filtered.Any()) {
                     byte[] bytes = JsonSerializer.SerializeToUtf8Bytes(filtered.Select(o => new {
-                        timestamp  = o.timestamp / 10000 - 62135596800000,
+                        timestamp  = o.timestamp / 10000 - UNIX_BASE_TICKS,
                         severity   = o.severity,
                         issue      = o.message,
                         name       = o.name,
@@ -206,7 +209,7 @@ private static void ScanDevices() {
         CheckMacAddresses();
 
         foreach (KeyValuePair<string, Database.Entry> host in ipAddresses) {
-            if (CheckRtt(host.Value, host.Key, out Issue? issue)) {
+            if (CheckRtt(host.Value, host.Key, out Issue? issue) && issue.HasValue) {
                 issues.Add(issue.Value);
             }
         }

Protest/Tasks/Lifeline.cs

@@ -189,7 +189,7 @@ private static void LifelineLoop() {
             wmiThread?.Join();
             snmpThread?.Join();
 
-            task.status = TaskWrapper.TaskStatus.Idle;
+            task?.status = TaskWrapper.TaskStatus.Idle;
             task.Sleep(Math.Max((int)((TWO_HOURS_IN_TICKS - (DateTime.UtcNow.Ticks - startTimeStamp)) / 10_000), 0));
 
             if (task.cancellationToken.IsCancellationRequested) {

Protest/Tasks/Watchdog.cs

@@ -138,7 +138,7 @@ private static void WatchLoop() {
         Thread.Sleep((int)gap);
 
         while (true) {
-            task.status = TaskWrapper.TaskStatus.Running;
+            task?.status = TaskWrapper.TaskStatus.Running;
 
             long loopStartTimeStamp = DateTime.UtcNow.Ticks;
 

Protest/Tools/IpDiscovery.cs

@@ -219,10 +219,10 @@ private static void DiscoverAdapter(ConcurrentDictionary<string, HostEntry> dic,
         }
 
         if (gwIpV4 is not null || gwIpV6 is not null) {
-            string ipv4String = gwIpV4.ToString();
+            string ipv4String = gwIpV4?.ToString() ?? null;
 
-            string hostname = NetBios.GetBiosName(ipv4String, 200);
-            string mac = Arp.ArpRequest(ipv4String);
+            string hostname = ipv4String is null ? String.Empty : NetBios.GetBiosName(ipv4String, 200);
+            string mac      = ipv4String is null ? String.Empty : Arp.ArpRequest(ipv4String);
 
             HostEntry gwHost = new HostEntry() {
                 description  = String.Empty,

Protest/Tools/LiveStats.cs

@@ -379,9 +379,7 @@ private static void WmiQuery(WebSocket ws, Lock mutex, string firstAlive, ref st
                 WsWriteText(ws, $"{{\"activeUser\":\"{Data.EscapeJsonText(username)}\",\"source\":\"WMI\"}}", mutex);
             }
         }
-        catch (NullReferenceException ex) {
-            Logger.Error(ex);
-        }
+        //catch (NullReferenceException) { }
         catch { }
     }