Question

Is there a way or special curl option to recognize a no-connection-situation when curlGetResponse_ is used?

For example, there is some curl-command:

withCurlDo $ respBody <$> (curlGetResponse_ "google.com" [CurlFailOnError True] ∷ IO (CurlResponse_ [(String, String)] ByteString))

If there is a connection to host, it returns some IO ByteString.

But if there is no any connection, it takes 40 seconds and returns empty string.

Is there a way to throw and exception or some Left value, when connection is lost and host is unreachable?

Answer 1

You can set appropriate timeout with ConnectTimeout option and then check response code for timeout errors:

μ> withCurlDo $ respCurlCode <$> (curlGetResponse_ "google.com" [CurlConnectTimeout 1] ∷ IO (CurlResponse_ [(String, String)] String))
CurlOK
μ> withCurlDo $ respCurlCode <$> (curlGetResponse_ "2.2.2.2" [CurlConnectTimeout 1] ∷ IO (CurlResponse_ [(String, String)] String))
CurlOperationTimeout