v0.6

Fix record cache eviction
Documentation

Author: jdomnitz

TinyDNS/Cache/RecordCache.cs

@@ -19,42 +19,44 @@ internal sealed class RecordCache
     {
         readonly int sizeLimit;
         readonly TimeSpan ttl;
-        private readonly ConcurrentStack<RecordEntry> stack = new ConcurrentStack<RecordEntry>();
+        private readonly ConcurrentQueue<RecordEntry> cache = new ConcurrentQueue<RecordEntry>();
 
         public RecordCache(int sizeLimit, TimeSpan ttl)
         {
             this.sizeLimit = sizeLimit;
             this.ttl = ttl;
-
         }
 
         public void Clear()
         {
-            stack.Clear();
+            cache.Clear();
         }
 
-        public bool Cached(Message message, IPAddress endPoint)
+        public bool Cached(Message message, IPAddress endPointIP)
         {
             Expire();
             RecordEntry entry = new RecordEntry();
             entry.message = message;
-            entry.Address = endPoint;
+            entry.Address = endPointIP;
             entry.Time = DateTime.Now;
-            if (stack.Contains(entry))
-                return true;
-            stack.Push(entry);
-            if (stack.Count > sizeLimit)
-                stack.TryPop(out _);
+            lock (cache)
+            {
+                if (cache.Contains(entry))
+                    return true;
+                cache.Enqueue(entry);
+            }
+            if (cache.Count > sizeLimit)
+                cache.TryDequeue(out _);
             return false;
         }
 
         private void Expire()
         {
-            while (stack.TryPeek(out RecordEntry entry))
+            while (cache.TryPeek(out RecordEntry entry))
             {
                 if (entry.Time + ttl > DateTime.Now)
                     return;
-                stack.TryPop(out _);
+                cache.TryDequeue(out _);
             }
         }
     }

TinyDNS/Cache/RecordEntry.cs

@@ -22,10 +22,19 @@ internal struct RecordEntry : IEquatable<RecordEntry>
 
         public bool Equals(RecordEntry other)
         {
-            if (Address.Equals(other.Address))
-                return message.Equals(other.message);
+            return message.Equals(other.message);
+        }
 
+        public override bool Equals(object? obj)
+        {
+            if (obj is RecordEntry entry)
+                return Equals(entry);
             return false;
         }
+
+        public override int GetHashCode()
+        {
+            return message.GetHashCode();
+        }
     }
 }

TinyDNS/DNSResolver.cs

@@ -26,20 +26,31 @@ public sealed class DNSResolver
         private readonly HashSet<IPAddress> globalNameservers = [];
         private ResolverCache cache = new ResolverCache();
         private ResolutionMode resolutionMode;
+        /// <summary>
+        /// Create a new DNS resolver
+        /// </summary>
+        /// <param name="mode">Which strategy to use to resolve queries</param>
         public DNSResolver(ResolutionMode mode = ResolutionMode.InsecureOnly)
         {
             this.resolutionMode = mode;
             ReloadNameservers();
             NetworkChange.NetworkAddressChanged += (s, e) => ReloadNameservers();
         }
-
+        /// <summary>
+        /// Create a new DNS resolver
+        /// </summary>
+        /// <param name="nameservers">the nameservers to query</param>
+        /// <param name="mode">Which strategy to use to resolve queries</param>
         public DNSResolver(List<IPAddress> nameservers, ResolutionMode mode = ResolutionMode.InsecureOnly)
         {
             this.resolutionMode = mode;
             foreach (IPAddress nameserver in nameservers)
                 this.globalNameservers.Add(nameserver);
         }
 
+        /// <summary>
+        /// The nameservers to query
+        /// </summary>
         public List<IPAddress> NameServers
         { 
             get
@@ -68,6 +79,11 @@ private void ReloadNameservers()
             }
         }
 
+        /// <summary>
+        /// Resolve a hostname to it's IP addresses
+        /// </summary>
+        /// <param name="hostname">domain name</param>
+        /// <returns>domain's IPs</returns>
         public async Task<List<IPAddress>> ResolveHost(string hostname)
         {
             ArgumentNullException.ThrowIfNullOrEmpty(hostname, nameof(hostname));
@@ -79,6 +95,11 @@ .. await ResolveHostV6(hostname)
             return addresses;
         }
 
+        /// <summary>
+        /// Resolve a hostname to it's IP v4 addresses
+        /// </summary>
+        /// <param name="hostname">domain name</param>
+        /// <returns>domain's IPs</returns>
         public async Task<List<IPAddress>> ResolveHostV4(string hostname)
         {
             ArgumentNullException.ThrowIfNullOrEmpty(hostname, nameof(hostname));
@@ -100,6 +121,11 @@ public async Task<List<IPAddress>> ResolveHostV4(string hostname)
             return addresses;
         }
 
+        /// <summary>
+        /// Resolve a hostname to it's IPv6 addresses
+        /// </summary>
+        /// <param name="hostname">domain name</param>
+        /// <returns>domain's IPs</returns>
         public async Task<List<IPAddress>> ResolveHostV6(string hostname)
         {
             ArgumentNullException.ThrowIfNullOrEmpty(hostname, nameof(hostname));
@@ -121,6 +147,12 @@ public async Task<List<IPAddress>> ResolveHostV6(string hostname)
             return addresses;
         }
 
+        /// <summary>
+        /// Lookup the domain name for an IP address
+        /// </summary>
+        /// <param name="address"></param>
+        /// <returns>The response message</returns>
+        /// <exception cref="ArgumentNullException"></exception>
         public async Task<Message?> ResolveIPRecord(IPAddress address)
         {
             if (address == null)
@@ -129,6 +161,12 @@ public async Task<List<IPAddress>> ResolveHostV6(string hostname)
             bool privateQuery = IsPrivate(address, addressBytes);
             return await ResolveQuery(new QuestionRecord(DomainParser.FromIP(addressBytes), DNSRecordType.PTR, false), privateQuery);
         }
+
+        /// <summary>
+        /// Lookup the domain name for an IP address
+        /// </summary>
+        /// <param name="address"></param>
+        /// <returns>The domain</returns>
         public async Task<string?> ResolveIP(IPAddress address)
         {
             Message? response = await ResolveIPRecord(address);
@@ -143,6 +181,11 @@ public async Task<List<IPAddress>> ResolveHostV6(string hostname)
             return null;
         }
 
+        /// <summary>
+        /// Sends a query and returns the response message
+        /// </summary>
+        /// <param name="question"></param>
+        /// <returns></returns>
         public async Task<Message?> ResolveQuery(QuestionRecord question)
         {
             bool privateQuery = (question.Name.Last() == "local");

TinyDNS/DomainParser.cs

@@ -11,6 +11,7 @@
 // along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 using System.Globalization;
+using System.Net;
 using System.Text;
 
 namespace TinyDNS
@@ -108,6 +109,11 @@ public static List<string> Parse(string domain)
             return labels;
         }
 
+        internal static List<string> FromIP(IPAddress address)
+        {
+            return FromIP(address.GetAddressBytes());
+        }
+
         internal static List<string> FromIP(byte[] address)
         {
             List<string> host;

TinyDNS/MDNS.cs

@@ -208,7 +208,7 @@ public async Task Query(List<string> domain, DNSRecordType type, bool unicastRes
 
         public async Task<List<Message>> ResolveInverseQuery(IPAddress address, bool unicastResponse = false)
         {
-            var domain = DomainParser.FromIP(address.GetAddressBytes());
+            var domain = DomainParser.FromIP(address);
             List<Message> responses = new List<Message>();
             MessageEventHandler handler = delegate (DNSMessageEvent e)
             {

TinyDNS/Message.cs

@@ -142,7 +142,9 @@ public bool Equals(Message? other)
 
         public override bool Equals(object? obj)
         {
-            return Equals(obj as Message);
+            if (obj is Message message)
+                return Equals(message);
+            return false;
         }
 
         public override string ToString()

TinyDNS/TinyDNS.csproj

@@ -4,7 +4,7 @@
     <TargetFrameworks>net80</TargetFrameworks>
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
-    <Version>0.5</Version>
+    <Version>0.6</Version>
     <PackageLicenseExpression>AGPL-3.0-or-later</PackageLicenseExpression>
     <PackageReadmeFile>README.md</PackageReadmeFile>
     <Authors>jdomnitz</Authors>