internal/socket: don't crash with corrupted control messages

Change-Id: I5c484662add4261f504607758521718f4c760375
Reviewed-on: https://go-review.googlesource.com/45294
TryBot-Result: Gobot Gobot <gobot@golang.org>
Run-TryBot: Matt Layher <mdlayher@gmail.com>
Reviewed-by: Matt Layher <mdlayher@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
1 file changed