add pending enrollment identifier

Disco.Services/Devices/Enrolment/EnrolmentLog.cs

@@ -81,14 +81,15 @@ namespace Disco.Services.Devices.Enrolment
                 System.Enum.GetName(EnrolmentType.GetType(), EnrolmentType)
             });
         }
-        public static void LogSessionPending(string SessionId, string HostId, EnrolmentTypes EnrolmentType, string Reason)
+        public static void LogSessionPending(string SessionId, string HostId, EnrolmentTypes EnrolmentType, string Reason, string Identifier)
         {
             Log(EventTypeIds.SessionPending, new object[]
             {
                 SessionId,
                 HostId,
                 System.Enum.GetName(EnrolmentType.GetType(), EnrolmentType),
-                Reason
+                Reason,
+                Identifier
             });
         }
         public static void LogSessionPendingApproved(string SessionId, string Username, string Reason)
@@ -383,7 +384,7 @@ namespace Disco.Services.Devices.Enrolment
                     Id = (int)EventTypeIds.SessionPending,
                     ModuleId = _ModuleId,
                     Name = "Session Pending",
-                    Format = "Pending '{2}' Enrollment for {1} (Session# {0}; Reason: {3})",
+                    Format = "Pending '{2}' Enrollment for {1} (Session# {0}; Reason: {3}; Identifier: {4})",
                     Severity = 0,
                     UseLive = true,
                     UsePersist = true,

Disco.Services/Devices/Enrolment/WindowsDeviceEnrolment.cs

@@ -14,6 +14,8 @@ namespace Disco.Services.Devices.Enrolment
 {
     public static class WindowsDeviceEnrolment
     {
+        private static readonly string pendingIdentifierAlphabet = "23456789ABCDEFGHJKMNPQRSTWXYZ";
+        private static readonly Random pendingIdentifierRng = new Random();
         private static readonly ConcurrentDictionary<string, EnrolResponse> pendingEnrolments = new ConcurrentDictionary<string, EnrolResponse>();
 
         private static void CleanupPendingEnrolments()
@@ -26,6 +28,28 @@ namespace Disco.Services.Devices.Enrolment
                 pendingEnrolments.TryRemove(expiredEnrolment, out _);
         }
 
+        private static string GeneratePendingIdentifier()
+        {
+            var identifier = default(string);
+            var chars = new char[4];
+            var retryAllowed = 100;
+            while (--retryAllowed > 0)
+            {
+                lock (pendingIdentifierRng)
+                {
+                    for (var i = 0; i < chars.Length; i++)
+                    {
+                        chars[i] = pendingIdentifierAlphabet[pendingIdentifierRng.Next(pendingIdentifierAlphabet.Length)];
+                    }
+                }
+                    identifier = new string(chars);
+
+                if (!GetPendingEnrolments().Any(e => string.Equals(e.PendingIdentifier, identifier, StringComparison.Ordinal)))
+                    break;
+            }
+            return identifier;
+        }
+
         public static List<EnrolResponse> GetPendingEnrolments()
         {
             var now = DateTimeOffset.Now;
@@ -185,8 +209,9 @@ namespace Disco.Services.Devices.Enrolment
                             response.PendingAuthorization = Convert.ToBase64String(authBytes);
                         }
                         response.PendingTimeout = DateTimeOffset.Now.Add(Database.DiscoConfiguration.Bootstrapper.PendingTimeout);
+                        response.PendingIdentifier = GeneratePendingIdentifier();
 
-                        EnrolmentLog.LogSessionPending(sessionId, Request.SerialNumber, EnrolmentTypes.Normal, response.PendingReason);
+                        EnrolmentLog.LogSessionPending(sessionId, Request.SerialNumber, EnrolmentTypes.Normal, response.PendingReason, response.PendingIdentifier);
 
                         if (pendingEnrolments.TryAdd(sessionId, response))
                             return response;