Add webhook delivery functionality with retry mechanism and signature verification.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: 9111ef36-26c8-4085-84ca-a35dc1fec1b5
Replit-Commit-Screenshot-Url: https://storage.googleapis.com/screenshot-production-us-central1/7083d608-d6d3-4a6a-9a27-6286c5109627/b326a816-600f-4a2f-a1f3-248f0b7ffba1.jpg

server/utils/webhook.ts

@@ -0,0 +1,118 @@
+import { createHmac } from 'crypto';
+import fetch from 'node-fetch';
+import { Webhook } from '@shared/schema';
+
+// Generates a signature for a webhook payload using the webhook's secret
+export function generateSignature(payload: any, secret: string): string {
+  if (!secret) return '';
+  
+  const hmac = createHmac('sha256', secret);
+  hmac.update(JSON.stringify(payload));
+  return hmac.digest('hex');
+}
+
+// Interface for webhook delivery results
+export interface WebhookDeliveryResult {
+  success: boolean;
+  statusCode?: number;
+  message: string;
+  timestamp: Date;
+  responseBody?: string;
+  retryCount?: number;
+}
+
+// Interface for webhook delivery logs
+export interface WebhookDeliveryLog {
+  id: string;
+  webhookId: string;
+  event: string;
+  payload: any;
+  signature: string;
+  result: WebhookDeliveryResult;
+  createdAt: Date;
+}
+
+/**
+ * Delivers a webhook payload to the configured URL with retry capability
+ */
+export async function deliverWebhook(
+  webhook: Webhook, 
+  payload: any, 
+  maxRetries = 3,
+  initialRetryDelay = 2000
+): Promise<WebhookDeliveryResult> {
+  let retryCount = 0;
+  let lastError: Error | null = null;
+  
+  // Generate HMAC signature if webhook has a secret
+  const signature = webhook.secret ? generateSignature(payload, webhook.secret) : '';
+  
+  while (retryCount <= maxRetries) {
+    try {
+      const headers: Record<string, string> = {
+        'Content-Type': 'application/json',
+        'User-Agent': 'DNS-Manager-Webhook/1.0',
+        'X-Webhook-ID': webhook.id,
+        'X-Webhook-Event': payload.event
+      };
+      
+      // Add signature header if available
+      if (signature) {
+        headers['X-Webhook-Signature'] = signature;
+      }
+      
+      const response = await fetch(webhook.url, {
+        method: 'POST',
+        headers,
+        body: JSON.stringify(payload),
+        timeout: 10000 // 10 second timeout
+      });
+      
+      const responseText = await response.text();
+      
+      if (response.ok) {
+        return {
+          success: true,
+          statusCode: response.status,
+          message: 'Webhook delivered successfully',
+          timestamp: new Date(),
+          responseBody: responseText,
+          retryCount
+        };
+      } else {
+        lastError = new Error(`HTTP error ${response.status}: ${responseText}`);
+        
+        // If we got a response but it's an error, check if it's a 5xx error that warrants retrying
+        if (response.status < 500 || retryCount >= maxRetries) {
+          break; // Don't retry client errors or if we've exhausted retries
+        }
+      }
+    } catch (error) {
+      lastError = error as Error;
+    }
+    
+    // Exponential backoff for retries
+    const delay = initialRetryDelay * Math.pow(2, retryCount);
+    await new Promise(resolve => setTimeout(resolve, delay));
+    retryCount++;
+  }
+  
+  return {
+    success: false,
+    statusCode: lastError && 'statusCode' in lastError ? (lastError as any).statusCode : undefined,
+    message: lastError ? lastError.message : 'Unknown error delivering webhook',
+    timestamp: new Date(),
+    retryCount
+  };
+}
+
+/**
+ * Creates a verification helper for clients to validate webhook signatures
+ */
+export function createSignatureVerifier(secret: string) {
+  return {
+    verify: (signature: string, payload: any): boolean => {
+      return signature === generateSignature(payload, secret);
+    }
+  };
+}