Fixed: Ensure SSL cert exists before saving config

Trap missing certificate exception to avoid bootloop

Fixes #4403

src/NzbDrone.Core/Validation/Paths/FileExistsValidator.cs

@@ -0,0 +1,26 @@
+using FluentValidation.Validators;
+using NzbDrone.Common.Disk;
+
+namespace NzbDrone.Core.Validation.Paths
+{
+    public class FileExistsValidator : PropertyValidator
+    {
+        private readonly IDiskProvider _diskProvider;
+
+        public FileExistsValidator(IDiskProvider diskProvider)
+            : base("File does not exist")
+        {
+            _diskProvider = diskProvider;
+        }
+
+        protected override bool IsValid(PropertyValidatorContext context)
+        {
+            if (context.PropertyValue == null)
+            {
+                return false;
+            }
+
+            return _diskProvider.FileExists(context.PropertyValue.ToString());
+        }
+    }
+}

src/NzbDrone.Host/WebHost/WebHostController.cs

@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
+using System.Security.Cryptography;
 using System.Security.Cryptography.X509Certificates;
 using Microsoft.AspNetCore.Builder;
 using Microsoft.AspNetCore.Hosting;
@@ -10,6 +11,7 @@
 using NLog;
 using NLog.Extensions.Logging;
 using NzbDrone.Common.EnvironmentInfo;
+using NzbDrone.Common.Exceptions;
 using NzbDrone.Common.Extensions;
 using NzbDrone.Common.Serializer;
 using NzbDrone.Core.Configuration;
@@ -72,7 +74,21 @@ public void StartServer()
                     {
                         options.ConfigureHttpsDefaults(configureOptions =>
                         {
-                            var certificate = new X509Certificate2(_configFileProvider.SslCertPath, _configFileProvider.SslCertPassword, X509KeyStorageFlags.DefaultKeySet);
+                            X509Certificate2 certificate;
+
+                            try
+                            {
+                                certificate = new X509Certificate2(sslCertPath, _configFileProvider.SslCertPassword, X509KeyStorageFlags.DefaultKeySet);
+                            }
+                            catch (CryptographicException ex)
+                            {
+                                if (ex.HResult == 0x2 || ex.HResult == 0x2006D080)
+                                {
+                                    throw new RadarrStartupException(ex, $"The SSL certificate file {sslCertPath} does not exist");
+                                }
+
+                                throw new RadarrStartupException(ex);
+                            }
 
                             configureOptions.ServerCertificate = certificate;
                         });

src/Radarr.Api.V3/Config/HostConfigModule.cs

@@ -1,6 +1,7 @@
 using System.IO;
 using System.Linq;
 using System.Reflection;
+using System.Security.Cryptography.X509Certificates;
 using FluentValidation;
 using NzbDrone.Common.Extensions;
 using NzbDrone.Core.Authentication;
@@ -18,7 +19,10 @@ public class HostConfigModule : RadarrRestModule<HostConfigResource>
         private readonly IConfigService _configService;
         private readonly IUserService _userService;
 
-        public HostConfigModule(IConfigFileProvider configFileProvider, IConfigService configService, IUserService userService)
+        public HostConfigModule(IConfigFileProvider configFileProvider,
+                                IConfigService configService,
+                                IUserService userService,
+                                FileExistsValidator fileExistsValidator)
             : base("/config/host")
         {
             _configFileProvider = configFileProvider;
@@ -43,7 +47,14 @@ public HostConfigModule(IConfigFileProvider configFileProvider, IConfigService c
 
             SharedValidator.RuleFor(c => c.SslPort).ValidPort().When(c => c.EnableSsl);
             SharedValidator.RuleFor(c => c.SslPort).NotEqual(c => c.Port).When(c => c.EnableSsl);
-            SharedValidator.RuleFor(c => c.SslCertPath).NotEmpty().When(c => c.EnableSsl);
+
+            SharedValidator.RuleFor(c => c.SslCertPath)
+                .Cascade(CascadeMode.StopOnFirstFailure)
+                .NotEmpty()
+                .IsValidPath()
+                .SetValidator(fileExistsValidator)
+                .Must((resource, path) => IsValidSslCertificate(resource)).WithMessage("Invalid SSL certificate file or password")
+                .When(c => c.EnableSsl);
 
             SharedValidator.RuleFor(c => c.Branch).NotEmpty().WithMessage("Branch name is required, 'master' is the default");
             SharedValidator.RuleFor(c => c.UpdateScriptPath).IsValidPath().When(c => c.UpdateMechanism == UpdateMechanism.Script);
@@ -53,6 +64,21 @@ public HostConfigModule(IConfigFileProvider configFileProvider, IConfigService c
             SharedValidator.RuleFor(c => c.BackupRetention).InclusiveBetween(1, 90);
         }
 
+        private bool IsValidSslCertificate(HostConfigResource resource)
+        {
+            X509Certificate2 cert;
+            try
+            {
+                cert = new X509Certificate2(resource.SslCertPath, resource.SslCertPassword, X509KeyStorageFlags.DefaultKeySet);
+            }
+            catch
+            {
+                return false;
+            }
+
+            return cert != null;
+        }
+
         private HostConfigResource GetHostConfig()
         {
             var resource = _configFileProvider.ToResource(_configService);