refactor(tunnel): check dest URL protocol

Previously, the NewTunnel function assumed that the destination
URL always starts with "http://" and added it if not present.
This commit refactors the logic to properly check for the scheme
and add "http://" if the scheme is missing or invalid.

The changes include:

* Checking for "http://" or "https://" prefixes in the destination
URL.
* If the prefix is missing or invalid, "http://" is appended to the
destination URL.
* This ensures that the ReverseProxy uses a valid destination URL
for forwarding requests.

This fix addresses potential issues when the destination URL is
provided without a proper scheme, leading to incorrect behavior of
the tunnel.

Signed-off-by: Dwi Siswanto <[email protected]>

pkg/tunnel/tunnel.go

@@ -22,7 +22,10 @@ func NewTunnel(port int, dest, cfgPath, optFormat string) (*Tunnel, error) {
 		return nil, common.ErrDestAddressEmpty
 	}
 
-	dest = "http://" + dest
+	if !strings.HasPrefix(dest, "http://") || !strings.HasPrefix(dest, "https://") {
+		dest = "http://" + dest
+	}
+
 	destURL, err := url.Parse(dest)
 	if err != nil {
 		return nil, err