1 files changed, 117 insertions, 0 deletions
diff --git a/src/main.lib/Plugins/ValidationPlugins/Dns/DnsValidation.cs b/src/main.lib/Plugins/ValidationPlugins/Dns/DnsValidation.cs
new file mode 100644
index 0000000..a9961d2
--- /dev/null
+++ b/src/main.lib/Plugins/ValidationPlugins/Dns/DnsValidation.cs
@@ -0,0 +1,117 @@
+using ACMESharp.Authorizations;
+using PKISharp.WACS.Clients.DNS;
+using PKISharp.WACS.Services;
+using Serilog.Context;
+using System;
+using System.Linq;
+using System.Net;
+using System.Threading;
+
+namespace PKISharp.WACS.Plugins.ValidationPlugins
+{
+    /// <summary>
+    /// Base implementation for DNS-01 validation plugins
+    /// </summary>
+    public abstract class DnsValidation<TOptions, TPlugin> : Validation<TOptions, Dns01ChallengeValidationDetails>
+    {
+        protected LookupClientProvider _dnsClientProvider { get; private set; }
+
+        protected DnsValidation(LookupClientProvider dnsClient, ILogService logService, TOptions options, string identifier) : 
+            base(logService, options, identifier)
+        {
+            _dnsClientProvider = dnsClient;
+        }
+
+        public override void PrepareChallenge()
+        {
+            CreateRecord(_challenge.DnsRecordName, _challenge.DnsRecordValue);
+            _log.Information("Answer should now be available at {answerUri}", _challenge.DnsRecordName);
+
+            // Verify that the record was created succesfully and wait for possible
+            // propagation/caching/TTL issues to resolve themselves naturally
+            var retry = 0;
+            var maxRetries = 5;
+            var retrySeconds = 30;
+            while (true)
+            {
+                if (PreValidate(retry))
+                {
+                    break;
+                }
+                else
+                {
+                    retry += 1;
+                    if (retry > maxRetries)
+                    {
+                        _log.Information("It looks like validation is going to fail, but we will try now anyway...");
+                        break;
+                    }
+                    else
+                    {
+                        _log.Information("Will retry in {s} seconds (retry {i}/{j})...", retrySeconds, retry, maxRetries);
+                        Thread.Sleep(retrySeconds * 1000);
+                    }
+                }
+            }
+        }
+
+        protected bool PreValidate(int attempt)
+        {
+            try
+            {
+                var dnsClient = _dnsClientProvider.GetClient(_challenge.DnsRecordName, attempt);
+                if (dnsClient.LookupClient.UseRandomNameServer)
+                {
+                    using (LogContext.PushProperty("NameServerIpAddresses", dnsClient.LookupClient.NameServers.Select(ns => ns.Endpoint.Address.ToString()), true))
+                    {
+                        _log.Debug("Using random name server");
+                    }
+                }
+                var tokens = dnsClient.GetTextRecordValues(_challenge.DnsRecordName, attempt).ToList();
+                if (tokens.Contains(_challenge.DnsRecordValue))
+                {
+                    _log.Information("Preliminary validation succeeded: {ExpectedTxtRecord} found in {TxtRecords}", _challenge.DnsRecordValue, String.Join(", ", tokens));
+                    return true;
+                }
+                else if (!tokens.Any())
+                {
+                    _log.Warning("Preliminary validation failed: no TXT records found");
+                }
+                else
+                {
+                    _log.Warning("Preliminary validation failed: {ExpectedTxtRecord} not found in {TxtRecords}", _challenge.DnsRecordValue, String.Join(", ", tokens));
+                }
+            }
+            catch (Exception ex)
+            {
+                _log.Error(ex, "Preliminary validation failed");
+            }
+            return false;
+        }
+
+        /// <summary>
+        /// Delete record when we're done
+        /// </summary>
+        public override void CleanUp()
+        {
+            if (_challenge != null)
+            {
+                DeleteRecord(_challenge.DnsRecordName, _challenge.DnsRecordValue);
+            }
+        }
+
+        /// <summary>
+        /// Delete validation record
+        /// </summary>
+        /// <param name="recordName">Name of the record</param>
+        public abstract void DeleteRecord(string recordName, string token);
+
+        /// <summary>
+        /// Create validation record
+        /// </summary>
+        /// <param name="recordName">Name of the record</param>
+        /// <param name="token">Contents of the record</param>
+        public abstract void CreateRecord(string recordName, string token);
+
+    }
+}