Improves robustness of zone parsing.

alanedwardes · Feb 10, 2024 · 856a0d0 · 856a0d0
1 parent 82c9017
commit 856a0d0
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Showing 8 changed files with 147 additions and 14 deletions.
diff --git a/src/Ae.Dns.Protocol/Records/DnsResourceRecord.cs b/src/Ae.Dns.Protocol/Records/DnsResourceRecord.cs
@@ -129,14 +129,42 @@ public string ToZone(IDnsZone zone)
         /// <inheritdoc/>
         public void FromZone(IDnsZone zone, string input)
         {
-            var parts = input.Split(null, 5);
+            var parts = input.Split(Array.Empty<char>(), StringSplitOptions.RemoveEmptyEntries);
 
-            Host = zone.FromFormattedHost(parts[0]);
-            TimeToLive = uint.Parse(parts[1]);
-            Class = (DnsQueryClass)Enum.Parse(typeof(DnsQueryClass), parts[2]);
-            Type = (DnsQueryType)Enum.Parse(typeof(DnsQueryType), parts[3]);
+            var index = 0;
+
+            if (char.IsWhiteSpace(input.First()))
+            {
+                Host = zone.Records.Last().Host;
+            }
+            else
+            {
+                Host = zone.FromFormattedHost(parts[index++]);
+            }
+
+            if (uint.TryParse(parts[index], out var ttl))
+            {
+                TimeToLive = ttl;
+                index++;
+            }
+            else
+            {
+                TimeToLive = (uint)zone.DefaultTtl.TotalSeconds;
+            }
+
+            if (Enum.TryParse<DnsQueryClass>(parts[index], out var cl))
+            {
+                Class = cl;
+                index++;
+            }
+            else
+            {
+                Class = zone.Records.Last().Class;
+            }
+
+            Type = (DnsQueryType)Enum.Parse(typeof(DnsQueryType), parts[index++]);
             Resource = CreateResourceRecord(Type);
-            Resource.FromZone(zone, parts[4]);
+            Resource.FromZone(zone, string.Join(" ", parts.Skip(index)));
         }
     }
 }
diff --git a/src/Ae.Dns.Protocol/Records/DnsSoaResource.cs b/src/Ae.Dns.Protocol/Records/DnsSoaResource.cs
@@ -102,7 +102,7 @@ public void FromZone(IDnsZone zone, string input)
             MName = parts[0].Trim('.');
             RName = parts[1].Trim('.');
 
-            var parts1 = parts[2].Trim(new[] { '(', ')' }).Split(null);
+            var parts1 = parts[2].Trim(new[] { '(', ')' }).Split(Array.Empty<char>(), StringSplitOptions.RemoveEmptyEntries);
             Serial = uint.Parse(parts1[0]);
             Refresh = TimeSpan.FromSeconds(int.Parse(parts1[1]));
             Retry = TimeSpan.FromSeconds(int.Parse(parts1[2]));

diff --git a/src/Ae.Dns.Protocol/Records/DnsTextResource.cs b/src/Ae.Dns.Protocol/Records/DnsTextResource.cs
@@ -1,5 +1,4 @@
 using Ae.Dns.Protocol.Zone;
-using System;
 using System.Linq;
 
 namespace Ae.Dns.Protocol.Records

diff --git a/src/Ae.Dns.Protocol/Zone/DnsZone.cs b/src/Ae.Dns.Protocol/Zone/DnsZone.cs
@@ -1,5 +1,4 @@
-using Ae.Dns.Protocol.Enums;
-using Ae.Dns.Protocol.Records;
+using Ae.Dns.Protocol.Records;
 using System;
 using System.Collections.Generic;
 using System.IO;
@@ -19,6 +18,22 @@ public sealed class DnsZone : IDnsZone
         private readonly List<DnsResourceRecord> _records = new List<DnsResourceRecord>();
         private readonly SemaphoreSlim _semaphore = new SemaphoreSlim(1, 1);
 
+        /// <summary>
+        /// Construct a new <see cref="DnsZone"/> with no records.
+        /// </summary>
+        public DnsZone()
+        {
+        }
+
+        /// <summary>
+        /// Construct a new <see cref="DnsZone"/> with the specified records.
+        /// </summary>
+        /// <param name="records"></param>
+        public DnsZone(IEnumerable<DnsResourceRecord> records)
+        {
+            _records = records.ToList();
+        }
+
         /// <inheritdoc/>
         public IReadOnlyList<DnsResourceRecord> Records => _records;
 
@@ -68,9 +83,35 @@ public void DeserializeZone(string zone)
 
             var reader = new StringReader(zone);
 
+            string? spillage = null;
             string? line;
+            bool spillover = false;
             while ((line = reader.ReadLine()) != null)
             {
+                line = line.Split(';')[0];
+
+                if (line.Contains("(") && !line.Contains(")"))
+                {
+                    spillover = true;
+                }
+
+                if (line.Contains(")"))
+                {
+                    line = spillage + line;
+                    spillover = false;
+                }
+
+                if (spillover)
+                {
+                    spillage += line;
+                    continue;
+                }
+
+                if (string.IsNullOrWhiteSpace(line))
+                {
+                    continue;
+                }
+
                 if (line.StartsWith("$ORIGIN"))
                 {
                     Origin = line.Substring("$ORIGIN".Length).Trim().Trim('.');

diff --git a/tests/Ae.Dns.Tests/Ae.Dns.Tests.csproj b/tests/Ae.Dns.Tests/Ae.Dns.Tests.csproj
@@ -50,4 +50,10 @@
 		</None>
 	</ItemGroup>
 
+	<ItemGroup>
+	  <None Update="Zone\*.zone">
+	    <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+	  </None>
+	</ItemGroup>
+
 </Project>
diff --git a/tests/Ae.Dns.Tests/Zone/DnsZoneTests.cs b/tests/Ae.Dns.Tests/Zone/DnsZoneTests.cs
@@ -2,6 +2,8 @@
 using Ae.Dns.Protocol.Records;
 using Ae.Dns.Protocol.Zone;
 using System;
+using System.IO;
+using System.Linq;
 using System.Net;
 using System.Threading.Tasks;
 using Xunit;
@@ -11,10 +13,9 @@ namespace Ae.Dns.Tests.Zone
     [Obsolete]
     public sealed class DnsZoneTests
     {
-        [Fact]
-        public async Task TestRoundTripZone()
+        private IDnsZone _wikipediaExampleZone = new DnsZone(new[]
         {
-            var zone = await RoundTripRecords(new DnsResourceRecord
+            new DnsResourceRecord
             {
                 Class = DnsQueryClass.IN,
                 Type = DnsQueryType.SOA,
@@ -129,7 +130,17 @@ public async Task TestRoundTripZone()
                 Host = "mail3.example.com",
                 TimeToLive = 3600,
                 Resource = new DnsIpAddressResource { IPAddress = IPAddress.Parse("192.0.2.5") }
-            });
+            }
+        })
+        {
+            Origin = "example.com",
+            DefaultTtl = TimeSpan.FromHours(1)
+        };
+
+        [Fact]
+        public async Task TestRoundTripZone()
+        {
+            var zone = await RoundTripRecords(_wikipediaExampleZone.Records.ToArray());
 
             Assert.NotNull(zone);
         }
@@ -163,6 +174,26 @@ public async Task TestTxtResource()
             Assert.NotNull(zone);
         }
 
+        [Fact]
+        public async Task TestLoadZone1()
+        {
+            var zone = new DnsZone();
+            zone.DeserializeZone(await File.ReadAllTextAsync("Zone/test1.zone"));
+
+            Assert.Equal(zone.Records, _wikipediaExampleZone.Records);
+
+            var serialized = await RoundTripRecords(zone.Records.ToArray());
+
+            Assert.NotNull(serialized);
+        }
+
+        [Fact]
+        public async Task TestLoadZone2()
+        {
+            var zone = new DnsZone();
+            zone.DeserializeZone(await File.ReadAllTextAsync("Zone/test2.zone"));
+        }
+
         public async Task<string> RoundTripRecords(params DnsResourceRecord[] records)
         {
             var originalZone = new DnsZone

diff --git a/tests/Ae.Dns.Tests/Zone/test1.zone b/tests/Ae.Dns.Tests/Zone/test1.zone
@@ -0,0 +1,17 @@
+$ORIGIN example.com.     ; designates the start of this zone file in the namespace
+$TTL 3600                ; default expiration time (in seconds) of all RRs without their own TTL value
+example.com.  IN  SOA   ns.example.com. username.example.com. ( 2020091025 7200 3600 1209600 3600 )
+example.com.  IN  NS    ns                    ; ns.example.com is a nameserver for example.com
+example.com.  IN  NS    ns.somewhere.example. ; ns.somewhere.example is a backup nameserver for example.com
+example.com.  IN  MX    10 mail.example.com.  ; mail.example.com is the mailserver for example.com
+@             IN  MX    20 mail2.example.com. ; equivalent to above line, "@" represents zone origin
+@             IN  MX    50 mail3              ; equivalent to above line, but using a relative host name
+example.com.  IN  A     192.0.2.1             ; IPv4 address for example.com
+              IN  AAAA  2001:db8:10::1        ; IPv6 address for example.com
+ns            IN  A     192.0.2.2             ; IPv4 address for ns.example.com
+              IN  AAAA  2001:db8:10::2        ; IPv6 address for ns.example.com
+www           IN  CNAME example.com.          ; www.example.com is an alias for example.com
+wwwtest       IN  CNAME www                   ; wwwtest.example.com is another alias for www.example.com
+mail          IN  A     192.0.2.3             ; IPv4 address for mail.example.com
+mail2         IN  A     192.0.2.4             ; IPv4 address for mail2.example.com
+mail3         IN  A     192.0.2.5             ; IPv4 address for mail3.example.com
diff --git a/tests/Ae.Dns.Tests/Zone/test2.zone b/tests/Ae.Dns.Tests/Zone/test2.zone
@@ -0,0 +1,11 @@
+$ORIGIN localhost.
+@  86400  IN  SOA   @  root (
+                  1999010100 ; serial
+                       10800 ; refresh (3 hours)
+                         900 ; retry (15 minutes)
+                      604800 ; expire (1 week)
+                       86400 ; minimum (1 day)
+                    )
+@  86400  IN  NS    @
+@  86400  IN  A     127.0.0.1
+@  86400  IN  AAAA  ::1