[release-branch.go1.7] net: don't avoid resolving .local addresses

.local addresses are used by things like Kubernetes and Weave DNS; Go should not avoid resolving them. This is a partial revert of https://golang.org/cl/21328 which was too strict of an interpretation of RFC 6762. Fixes #16739 Change-Id: I349415b4eab5d61240dd18217bd95dc7d2105cd5 Reviewed-on: https://go-review.googlesource.com/27250 Reviewed-by: Brad Fitzpatrick <[email protected]> Run-TryBot: Brad Fitzpatrick <[email protected]> TryBot-Result: Gobot Gobot <[email protected]> Reviewed-on: https://go-review.googlesource.com/28632
golang · Sep 7, 2016 · 308bdd0 · 308bdd0
1 parent 9b4e323
commit 308bdd0
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Showing 2 changed files with 9 additions and 7 deletions.
diff --git a/src/net/dnsclient_unix.go b/src/net/dnsclient_unix.go
@@ -338,16 +338,17 @@ func lookup(ctx context.Context, name string, qtype uint16) (cname string, rrs [
 }
 
 // avoidDNS reports whether this is a hostname for which we should not
-// use DNS. Currently this includes only .onion and .local names,
-// per RFC 7686 and RFC 6762, respectively. See golang.org/issue/13705.
+// use DNS. Currently this includes only .onion, per RFC 7686. See
+// golang.org/issue/13705. Does not cover .local names (RFC 6762),
+// see golang.org/issue/16739.
 func avoidDNS(name string) bool {
 	if name == "" {
 		return true
 	}
 	if name[len(name)-1] == '.' {
 		name = name[:len(name)-1]
 	}
-	return stringsHasSuffixFold(name, ".onion") || stringsHasSuffixFold(name, ".local")
+	return stringsHasSuffixFold(name, ".onion")
 }
 
 // nameList returns a list of names for sequential DNS queries.

diff --git a/src/net/dnsclient_unix_test.go b/src/net/dnsclient_unix_test.go
@@ -112,10 +112,11 @@ func TestAvoidDNSName(t *testing.T) {
 		{"foo.ONION", true},
 		{"foo.ONION.", true},
 
-		{"foo.local.", true},
-		{"foo.local", true},
-		{"foo.LOCAL", true},
-		{"foo.LOCAL.", true},
+		// But do resolve *.local address; Issue 16739
+		{"foo.local.", false},
+		{"foo.local", false},
+		{"foo.LOCAL", false},
+		{"foo.LOCAL.", false},
 
 		{"", true}, // will be rejected earlier too