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Merge pull request #5145 from aojea/happyeyeballs

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use (sort of) happy-eyeballs for port-forwarding
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Mike Brown 2021-03-26 09:51:29 -05:00 committed by GitHub
commit 1b05b605c8
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1 changed files with 16 additions and 4 deletions
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20
pkg/cri/server/sandbox_portforward_linux.go
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@ -62,12 +62,24 @@ func (c *criService) portForward(ctx context.Context, id string, port int32, str
log.G(ctx).Infof("Executing port forwarding in network namespace %q", netNSPath)
err = netNSDo(func(_ ns.NetNS) error {
defer stream.Close()
// TODO: hardcoded to tcp4 because localhost resolves to ::1 by default if the system has IPv6 enabled.
// Theoretically happy eyeballs will try IPv6 first and fallback to IPv4
// but resolving localhost doesn't seem to return and IPv4 address, thus failing the connection.
// localhost can resolve to both IPv4 and IPv6 addresses in dual-stack systems
// but the application can be listening in one of the IP families only.
// golang has enabled RFC 6555 Fast Fallback (aka HappyEyeballs) by default in 1.12
// It means that if a host resolves to both IPv6 and IPv4, it will try to connect to any
// of those addresses and use the working connection.
// However, the implementation uses go routines to start both connections in parallel,
// and this cases that the connection is done outside the namespace, so we try to connect
// serially.
// We try IPv4 first to keep current behavior and we fallback to IPv6 if the connection fails.
// xref https://github.com/golang/go/issues/44922
var conn net.Conn
conn, err := net.Dial("tcp4", fmt.Sprintf("localhost:%d", port))
if err != nil {
return errors.Wrapf(err, "failed to dial %d", port)
var errV6 error
conn, errV6 = net.Dial("tcp6", fmt.Sprintf("localhost:%d", port))
if errV6 != nil {
return fmt.Errorf("failed to connect to localhost:%d inside namespace %q, IPv4: %v IPv6 %v ", port, id, err, errV6)
}
}
defer conn.Close()