net: make IPv6 capability test more suitable for address family selection on the dual IP stack node
For now we strictly use IPV6_V6ONLY=1 for IPv6-only communications
and IPV6_V6ONLY=0 for both IPv4 and IPv6 communications. So let the
capability test do the same.
LGTM=iant
R=golang-codereviews, gobot, iant
CC=golang-codereviews
https://golang.org/cl/80140044
diff --git a/src/pkg/net/ipsock_posix.go b/src/pkg/net/ipsock_posix.go
index d2f4506..2ba4c8e 100644
--- a/src/pkg/net/ipsock_posix.go
+++ b/src/pkg/net/ipsock_posix.go
@@ -40,12 +40,13 @@
func probeIPv6Stack() (supportsIPv6, supportsIPv4map bool) {
var probes = []struct {
laddr TCPAddr
+ value int
ok bool
}{
// IPv6 communication capability
- {TCPAddr{IP: ParseIP("::1")}, false},
+ {laddr: TCPAddr{IP: ParseIP("::1")}, value: 1},
// IPv6 IPv4-mapped address communication capability
- {TCPAddr{IP: IPv4(127, 0, 0, 1)}, false},
+ {laddr: TCPAddr{IP: IPv4(127, 0, 0, 1)}, value: 0},
}
for i := range probes {
@@ -54,7 +55,7 @@
continue
}
defer closesocket(s)
- syscall.SetsockoptInt(s, syscall.IPPROTO_IPV6, syscall.IPV6_V6ONLY, 0)
+ syscall.SetsockoptInt(s, syscall.IPPROTO_IPV6, syscall.IPV6_V6ONLY, probes[i].value)
sa, err := probes[i].laddr.sockaddr(syscall.AF_INET6)
if err != nil {
continue
