net: add mechanisms to force go or cgo lookup, and to debug default strategy
GODEBUG=netdns=1 prints a one-time strategy decision. (cgo or go DNS lookups)
GODEBUG=netdns=2 prints the per-lookup strategy as a function of the hostname.
The new "netcgo" build tag forces cgo DNS lookups.
GODEBUG=netdns=go (or existing build tag "netgo") forces Go DNS resolution.
GODEBUG=netdns=cgo (or new build tag "netcgo") forces libc DNS resolution.
Options can be combined with e.g. GODEBUG=netdns=go+1 or GODEBUG=netdns=2+cgo.
Fixes #11322
Fixes #11450
Change-Id: I7a67e9f759fd0a02320e7803f9ded1638b19e861
Reviewed-on: https://go-review.googlesource.com/11584
Reviewed-by: Russ Cox <rsc@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
diff --git a/src/net/conf_test.go b/src/net/conf_test.go
index 003c615..86904bf 100644
--- a/src/net/conf_test.go
+++ b/src/net/conf_test.go
@@ -295,3 +295,7 @@
}
}
+
+func TestSystemConf(t *testing.T) {
+ systemConf()
+}
