BlockListZoneManager: updated implementation of allowed list by having a separate allowed zone. Updated parser to detect inline comment. Added IsAllowed() method. Updated Query() to check count before query.

DnsServerCore/Dns/ZoneManagers/BlockListZoneManager.cs

@@ -43,6 +43,8 @@ namespace DnsServerCore.Dns.ZoneManagers
 
         readonly List<Uri> _allowListUrls = new List<Uri>();
         readonly List<Uri> _blockListUrls = new List<Uri>();
+
+        IReadOnlyDictionary<string, object> _allowListZone = new Dictionary<string, object>();
         IReadOnlyDictionary<string, List<Uri>> _blockListZone = new Dictionary<string, List<Uri>>();
 
         DnsSOARecordData _soaRecord;
@@ -109,9 +111,10 @@ namespace DnsServerCore.Dns.ZoneManagers
             return word;
         }
 
-        private Queue<string> ReadListFile(Uri listUrl, bool isAllowList, Dictionary<string, object> allowedDomains)
+        private Queue<string> ReadListFile(Uri listUrl, bool isAllowList, out Queue<string> exceptionDomains)
         {
             Queue<string> domains = new Queue<string>();
+            exceptionDomains = new Queue<string>();
 
             try
             {
@@ -141,7 +144,7 @@ namespace DnsServerCore.Dns.ZoneManagers
                         if (line.Length == 0)
                             continue; //skip empty line
 
-                        if (line.StartsWith("#") || line.StartsWith("!"))
+                        if (line.StartsWith('#') || line.StartsWith("!"))
                             continue; //skip comment line
 
                         if (line.StartsWith("||"))
@@ -153,38 +156,35 @@ namespace DnsServerCore.Dns.ZoneManagers
                                 domain = line.Substring(2, i - 2);
                                 options = line.Substring(i + 1);
 
-                                if (((options.Length == 0) || (options.StartsWith("$") && (options.Contains("doc") || options.Contains("all")))) && DnsClient.IsDomainNameValid(domain))
-                                    domains.Enqueue(domain);
+                                if (((options.Length == 0) || (options.StartsWith('$') && (options.Contains("doc") || options.Contains("all")))) && DnsClient.IsDomainNameValid(domain))
+                                    domains.Enqueue(domain.ToLower());
                             }
                             else
                             {
                                 domain = line.Substring(2);
 
                                 if (DnsClient.IsDomainNameValid(domain))
-                                    domains.Enqueue(domain);
+                                    domains.Enqueue(domain.ToLower());
                             }
                         }
                         else if (line.StartsWith("@@||"))
                         {
-                            //adblock format
-                            if (!isAllowList)
+                            //adblock format - exception syntax
+                            i = line.IndexOf('^');
+                            if (i > -1)
                             {
-                                i = line.IndexOf('^');
-                                if (i > -1)
-                                {
-                                    domain = line.Substring(4, i - 4);
-                                    options = line.Substring(i + 1);
+                                domain = line.Substring(4, i - 4);
+                                options = line.Substring(i + 1);
 
-                                    if (((options.Length == 0) || (options.StartsWith("$") && (options.Contains("doc") || options.Contains("all")))) && DnsClient.IsDomainNameValid(domain))
-                                        allowedDomains.TryAdd(domain, null);
-                                }
-                                else
-                                {
-                                    domain = line.Substring(4);
+                                if (((options.Length == 0) || (options.StartsWith('$') && (options.Contains("doc") || options.Contains("all")))) && DnsClient.IsDomainNameValid(domain))
+                                    exceptionDomains.Enqueue(domain.ToLower());
+                            }
+                            else
+                            {
+                                domain = line.Substring(4);
 
-                                    if (DnsClient.IsDomainNameValid(domain))
-                                        allowedDomains.TryAdd(domain, null);
-                                }
+                                if (DnsClient.IsDomainNameValid(domain))
+                                    exceptionDomains.Enqueue(domain.ToLower());
                             }
                         }
                         else
@@ -200,7 +200,7 @@ namespace DnsServerCore.Dns.ZoneManagers
                             {
                                 secondWord = PopWord(ref line);
 
-                                if (secondWord.Length == 0)
+                                if ((secondWord.Length == 0) || secondWord.StartsWith('#'))
                                     hostname = firstWord;
                                 else
                                     hostname = secondWord;
@@ -267,11 +267,13 @@ namespace DnsServerCore.Dns.ZoneManagers
             return null;
         }
 
-        private static bool IsZoneAllowed(Dictionary<string, object> allowedDomains, string domain)
+        private bool IsZoneAllowed(string domain)
         {
+            domain = domain.ToLower();
+
             do
             {
-                if (allowedDomains.TryGetValue(domain, out _))
+                if (_allowListZone.TryGetValue(domain, out _))
                     return true;
 
                 domain = AuthZoneManager.GetParentZone(domain);
@@ -287,37 +289,57 @@ namespace DnsServerCore.Dns.ZoneManagers
 
         public void LoadBlockLists()
         {
-            //read all allowed domains in dictionary
-            Dictionary<string, object> allowedDomains = new Dictionary<string, object>();
+            Dictionary<Uri, Queue<string>> allowListQueues = new Dictionary<Uri, Queue<string>>(_allowListUrls.Count);
+            Dictionary<Uri, Queue<string>> blockListQueues = new Dictionary<Uri, Queue<string>>(_blockListUrls.Count);
+            int totalAllowedDomains = 0;
+            int totalBlockedDomains = 0;
 
+            //read all allow lists in a queue
             foreach (Uri allowListUrl in _allowListUrls)
             {
-                Queue<string> queue = ReadListFile(allowListUrl, true, null);
+                if (!allowListQueues.ContainsKey(allowListUrl))
+                {
+                    Queue<string> allowListQueue = ReadListFile(allowListUrl, true, out Queue<string> blockListQueue);
+
+                    totalAllowedDomains += allowListQueue.Count;
+                    allowListQueues.Add(allowListUrl, allowListQueue);
+
+                    totalBlockedDomains += blockListQueue.Count;
+                    blockListQueues.Add(allowListUrl, blockListQueue);
+                }
+            }
+
+            //read all block lists in a queue
+            foreach (Uri blockListUrl in _blockListUrls)
+            {
+                if (!blockListQueues.ContainsKey(blockListUrl))
+                {
+                    Queue<string> blockListQueue = ReadListFile(blockListUrl, false, out Queue<string> allowListQueue);
+
+                    totalBlockedDomains += blockListQueue.Count;
+                    blockListQueues.Add(blockListUrl, blockListQueue);
+
+                    totalAllowedDomains += allowListQueue.Count;
+                    allowListQueues.Add(blockListUrl, allowListQueue);
+                }
+            }
+
+            //load block list zone
+            Dictionary<string, object> allowListZone = new Dictionary<string, object>(totalAllowedDomains);
+
+            foreach (KeyValuePair<Uri, Queue<string>> allowListQueue in allowListQueues)
+            {
+                Queue<string> queue = allowListQueue.Value;
 
                 while (queue.Count > 0)
                 {
                     string domain = queue.Dequeue();
 
-                    allowedDomains.TryAdd(domain, null);
+                    allowListZone.TryAdd(domain, null);
                 }
             }
 
-            //read all block lists in a queue
-            Dictionary<Uri, Queue<string>> blockListQueues = new Dictionary<Uri, Queue<string>>(_blockListUrls.Count);
-            int totalDomains = 0;
-
-            foreach (Uri blockListUrl in _blockListUrls)
-            {
-                if (!blockListQueues.ContainsKey(blockListUrl))
-                {
-                    Queue<string> blockListQueue = ReadListFile(blockListUrl, false, allowedDomains);
-                    totalDomains += blockListQueue.Count;
-                    blockListQueues.Add(blockListUrl, blockListQueue);
-                }
-            }
-
-            //load block list zone
-            Dictionary<string, List<Uri>> blockListZone = new Dictionary<string, List<Uri>>(totalDomains);
+            Dictionary<string, List<Uri>> blockListZone = new Dictionary<string, List<Uri>>(totalBlockedDomains);
 
             foreach (KeyValuePair<Uri, Queue<string>> blockListQueue in blockListQueues)
             {
@@ -327,9 +349,6 @@ namespace DnsServerCore.Dns.ZoneManagers
                 {
                     string domain = queue.Dequeue();
 
-                    if (IsZoneAllowed(allowedDomains, domain))
-                        continue; //domain is in allowed list so skip adding it to block list zone
-
                     if (!blockListZone.TryGetValue(domain, out List<Uri> blockLists))
                     {
                         blockLists = new List<Uri>(2);
@@ -340,16 +359,16 @@ namespace DnsServerCore.Dns.ZoneManagers
                 }
             }
 
-            //set new blocked zone
+            //set new allowed and blocked zones
+            _allowListZone = allowListZone;
             _blockListZone = blockListZone;
 
-            LogManager log = _dnsServer.LogManager;
-            if (log != null)
-                log.Write("DNS Server block list zone was loaded successfully.");
+            _dnsServer.LogManager?.Write("DNS Server block list zone was loaded successfully.");
         }
 
         public void Flush()
         {
+            _allowListZone = new Dictionary<string, object>();
             _blockListZone = new Dictionary<string, List<Uri>>();
         }
 
@@ -451,8 +470,19 @@ namespace DnsServerCore.Dns.ZoneManagers
             return downloaded || notModified;
         }
 
+        public bool IsAllowed(DnsDatagram request)
+        {
+            if (_allowListZone.Count < 1)
+                return false;
+
+            return IsZoneAllowed(request.Question[0].Name);
+        }
+
         public DnsDatagram Query(DnsDatagram request)
         {
+            if (_blockListZone.Count < 1)
+                return null;
+
             DnsQuestionRecord question = request.Question[0];
 
             List<Uri> blockLists = IsZoneBlocked(question.Name, out string blockedDomain);
@@ -572,6 +602,9 @@ namespace DnsServerCore.Dns.ZoneManagers
         public List<Uri> BlockListUrls
         { get { return _blockListUrls; } }
 
+        public int TotalZonesAllowed
+        { get { return _allowListZone.Count; } }
+
         public int TotalZonesBlocked
         { get { return _blockListZone.Count; } }