fix: safely parse resp payload

Sebastian Sauerer · Sebastian Sauerer · commit 4debe0c04ede · 2023-09-13T12:07:43.000+02:00
diff --git a/src/lambda-invoker.ts b/src/lambda-invoker.ts
@@ -27,11 +27,13 @@ export const invokeLambda = async (params: { payload: string, functionName: stri
     throw new Error(`Failed to invoke lambda ${params.functionName} synchronously`)
   }
 
-  if (hasTimeout(res)) {
-    throw new Error(res.Payload?.toString())
+  const safePayload = Buffer.from(res.Payload).toString('utf-8')
+
+  if (hasTimeout(res, safePayload)) {
+    throw new Error(safePayload)
   }
 
-  const response = safeParseJson(res.Payload?.transformToString())
+  const response = safeParseJson(safePayload)
 
   // response is not in JSON format
   if (!isApiGwStructuredResp(response)) {
@@ -55,4 +57,4 @@ const isApiGwStructuredResp = (resp: unknown): resp is APIGatewayProxyStructured
   return true
 }
 
-const hasTimeout = (res: InvocationResponse) => 'FunctionError' in res && res.Payload?.toString().includes('Task timed out')
+const hasTimeout = (res: InvocationResponse, safePayload: string) => 'FunctionError' in res && safePayload?.includes('Task timed out')

Original file line number	Diff line number	Diff line change
`@@ -27,11 +27,13 @@ export const invokeLambda = async (params: { payload: string, functionName: stri`
`27`	`27`	throw new Error(`Failed to invoke lambda ${params.functionName} synchronously`)
`28`	`28`	`}`
`29`	`29`
`30`		`- if (hasTimeout(res)) {`
`31`		`- throw new Error(res.Payload?.toString())`
	`30`	`+ const safePayload = Buffer.from(res.Payload).toString('utf-8')`
	`31`	`+`
	`32`	`+ if (hasTimeout(res, safePayload)) {`
	`33`	`+ throw new Error(safePayload)`
`32`	`34`	`}`
`33`	`35`
`34`		`- const response = safeParseJson(res.Payload?.transformToString())`
	`36`	`+ const response = safeParseJson(safePayload)`
`35`	`37`
`36`	`38`	`// response is not in JSON format`
`37`	`39`	`if (!isApiGwStructuredResp(response)) {`
`@@ -55,4 +57,4 @@ const isApiGwStructuredResp = (resp: unknown): resp is APIGatewayProxyStructured`
`55`	`57`	`return true`
`56`	`58`	`}`
`57`	`59`
`58`		`-const hasTimeout = (res: InvocationResponse) => 'FunctionError' in res && res.Payload?.toString().includes('Task timed out')`
	`60`	`+const hasTimeout = (res: InvocationResponse, safePayload: string) => 'FunctionError' in res && safePayload?.includes('Task timed out')`