Harden admin telemetry and deployment safeguards

TaxBaik.Web/Services/TelegramAlertGate.cs

@@ -0,0 +1,57 @@
+using System.Collections.Concurrent;
+using System.Security.Cryptography;
+using System.Text;
+
+namespace TaxBaik.Web.Services;
+
+internal static class TelegramAlertGate
+{
+    private sealed record GateEntry(DateTimeOffset WindowStart, int Count);
+
+    private static readonly ConcurrentDictionary<string, GateEntry> Gates = new();
+
+    public static bool ShouldSend(string category, string content, TimeSpan window, int maxPerWindow = 1)
+    {
+        if (string.IsNullOrWhiteSpace(category))
+            return false;
+
+        var now = DateTimeOffset.UtcNow;
+        var key = $"{category}:{Fingerprint(content)}";
+
+        while (true)
+        {
+            if (!Gates.TryGetValue(key, out var current))
+            {
+                var initial = new GateEntry(now, 1);
+                if (Gates.TryAdd(key, initial))
+                    return true;
+                continue;
+            }
+
+            if (now - current.WindowStart >= window)
+            {
+                var reset = new GateEntry(now, 1);
+                if (Gates.TryUpdate(key, reset, current))
+                    return true;
+                continue;
+            }
+
+            if (current.Count >= maxPerWindow)
+                return false;
+
+            var incremented = current with { Count = current.Count + 1 };
+            if (Gates.TryUpdate(key, incremented, current))
+                return true;
+        }
+    }
+
+    private static string Fingerprint(string content)
+    {
+        if (string.IsNullOrEmpty(content))
+            return "empty";
+
+        var normalized = content.Length > 1500 ? content[..1500] : content;
+        var bytes = SHA256.HashData(Encoding.UTF8.GetBytes(normalized));
+        return Convert.ToHexString(bytes);
+    }
+}

TaxBaik.Web/Services/TelegramNotificationService.cs

@@ -47,14 +47,29 @@ public class TelegramNotificationService : ITelegramNotificationService
             return;
         }
 
+        if (!TelegramAlertGate.ShouldSend("telegram:default", message, TimeSpan.FromMinutes(5)))
+            return;
+
         await SendToChat(_defaultChatId, message, ct);
     }
 
-    public async Task SendInquiryNotificationAsync(string message, CancellationToken ct = default) =>
-        await SendToChat(_inquiryChatId, $"<b>📋 문의 사항</b>\n\n{message}", ct);
+    public async Task SendInquiryNotificationAsync(string message, CancellationToken ct = default)
+    {
+        var text = $"<b>📋 문의 사항</b>\n\n{message}";
+        if (!TelegramAlertGate.ShouldSend("telegram:inquiry", text, TimeSpan.FromMinutes(10)))
+            return;
 
-    public async Task SendSystemNotificationAsync(string message, CancellationToken ct = default) =>
-        await SendToChat(_systemChatId, $"<b>🔧 시스템 알림</b>\n\n{message}", ct);
+        await SendToChat(_inquiryChatId, text, ct);
+    }
+
+    public async Task SendSystemNotificationAsync(string message, CancellationToken ct = default)
+    {
+        var text = $"<b>🔧 시스템 알림</b>\n\n{message}";
+        if (!TelegramAlertGate.ShouldSend("telegram:system", text, TimeSpan.FromMinutes(10)))
+            return;
+
+        await SendToChat(_systemChatId, text, ct);
+    }
 
     private async Task SendToChat(string chatId, string message, CancellationToken ct)
     {
@@ -89,18 +104,27 @@ public class TelegramNotificationService : ITelegramNotificationService
     public async Task SendErrorAsync(string title, string details, CancellationToken ct = default)
     {
         var message = $"<b>❌ {title}</b>\n\n{details}\n\n<i>{DateTime.UtcNow:yyyy-MM-dd HH:mm:ss} UTC</i>";
+        if (!TelegramAlertGate.ShouldSend("telegram:error", message, TimeSpan.FromMinutes(15)))
+            return;
+
         await SendToChat(_systemChatId, message, ct);
     }
 
     public async Task SendInfoAsync(string title, string message, CancellationToken ct = default)
     {
         var text = $"<b>ℹ️ {title}</b>\n\n{message}\n\n<i>{DateTime.UtcNow:yyyy-MM-dd HH:mm:ss} UTC</i>";
-        await SendMessageAsync(text, ct);
+        if (!TelegramAlertGate.ShouldSend("telegram:info", text, TimeSpan.FromMinutes(30)))
+            return;
+
+        await SendToChat(_defaultChatId, text, ct);
     }
 
     public async Task SendReportAsync(string reportTitle, string reportContent, CancellationToken ct = default)
     {
         var text = $"<b>📊 {reportTitle}</b>\n\n{reportContent}\n\n<i>{DateTime.UtcNow:yyyy-MM-dd HH:mm:ss} UTC</i>";
+        if (!TelegramAlertGate.ShouldSend("telegram:report", text, TimeSpan.FromHours(20)))
+            return;
+
         await SendToChat(_systemChatId, text, ct);
     }
 }