In addition to checking the total hostname length, validate characters used in each DNS label and label length. Updates https://github.com/tailscale/corp/issues/10012 Signed-off-by: Anton Tolchanov <anton@tailscale.com>
By default, `http.Transport` keeps idle connections open hoping to re-use them in the future. Combined with a separate transport per request in HTTP proxy this results in idle connection leak. Fixes #6773