chore: import upstream snapshot with attribution

apps/sim/lib/webhooks/providers/calcom.ts

@@ -0,0 +1,47 @@
+import { createLogger } from '@sim/logger'
+import { safeCompare } from '@sim/security/compare'
+import { hmacSha256Hex } from '@sim/security/hmac'
+import type { WebhookProviderHandler } from '@/lib/webhooks/providers/types'
+import { createHmacVerifier } from '@/lib/webhooks/providers/utils'
+
+const logger = createLogger('WebhookProvider:Calcom')
+
+function validateCalcomSignature(secret: string, signature: string, body: string): boolean {
+  try {
+    if (!secret || !signature || !body) {
+      logger.warn('Cal.com signature validation missing required fields', {
+        hasSecret: !!secret,
+        hasSignature: !!signature,
+        hasBody: !!body,
+      })
+      return false
+    }
+    let providedSignature: string
+    if (signature.startsWith('sha256=')) {
+      providedSignature = signature.substring(7)
+    } else {
+      providedSignature = signature
+    }
+    const computedHash = hmacSha256Hex(body, secret)
+    logger.debug('Cal.com signature comparison', {
+      computedSignature: `${computedHash.substring(0, 10)}...`,
+      providedSignature: `${providedSignature.substring(0, 10)}...`,
+      computedLength: computedHash.length,
+      providedLength: providedSignature.length,
+      match: computedHash === providedSignature,
+    })
+    return safeCompare(computedHash, providedSignature)
+  } catch (error) {
+    logger.error('Error validating Cal.com signature:', error)
+    return false
+  }
+}
+
+export const calcomHandler: WebhookProviderHandler = {
+  verifyAuth: createHmacVerifier({
+    configKey: 'webhookSecret',
+    headerName: 'X-Cal-Signature-256',
+    validateFn: validateCalcomSignature,
+    providerLabel: 'Cal.com',
+  }),
+}