Under some dial tests that require external network connectivity, we
must prevent application traffic but must not interfere with control
plane traffic such as DNS message exchange. But test helper function
disableSocketConnect prevents both application and control plane traffic
unconditionally and makes some dial tests with -ipv6 fail when
CGO_ENABLED=0.
This change makes disableSocketConnect take a look at not only address
family but socket type for fixing some dial tests with -ipv6 when
CGO_ENBALED=0.
Change-Id: I32241d9592d31483424bb5e69cb4d56f3fc20312
Reviewed-on: https://go-review.googlesource.com/8743
Reviewed-by: Ian Lance Taylor <iant@golang.org>
This change makes use of the socktest package instead of the non-thread
safe variable syscall.SocketDisableIPv6 for simulating unreachable
external networks.
Also adds -ipv4 flag, -ipv6 flag already exists, as a control knob for
testing on each of IPv4-only, IPv6-only and dual IP stack kernels.
Fixes#7687.
Change-Id: I82002007fd526e8cf4de207f935e721df049a22f
Reviewed-on: https://go-review.googlesource.com/8390
Reviewed-by: Ian Lance Taylor <iant@golang.org>
