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net/netcheck: clean up ICMP probe AddrPort lookup

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Fixes #14200

Change-Id: Ib086814cf63dda5de021403fe1db4fb2a798eaae
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
This commit is contained in:
Brad Fitzpatrick 2024-12-02 08:58:21 -08:00 committed by Brad Fitzpatrick
parent 24095e4897
commit 8d0c690f89
2 changed files with 36 additions and 29 deletions
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53
net/netcheck/netcheck.go
View File

@ -1221,17 +1221,19 @@ func (c *Client) measureICMPLatency(ctx context.Context, reg *tailcfg.DERPRegion
// Try pinging the first node in the region
node := reg.Nodes[0]
// Get the IPAddr by asking for the UDP address that we would use for
// STUN and then using that IP.
//
// TODO(andrew-d): this is a bit ugly
nodeAddr := c.nodeAddr(ctx, node, probeIPv4)
if !nodeAddr.IsValid() {
if node.STUNPort < 0 {
// If STUN is disabled on a node, interpret that as meaning don't measure latency.
return 0, false, nil
}
const unusedPort = 0
stunAddrPort, ok := c.nodeAddrPort(ctx, node, unusedPort, probeIPv4)
if !ok {
return 0, false, fmt.Errorf("no address for node %v (v4-for-icmp)", node.Name)
}
ip := stunAddrPort.Addr()
addr := &net.IPAddr{
IP: net.IP(nodeAddr.Addr().AsSlice()),
Zone: nodeAddr.Addr().Zone(),
IP: net.IP(ip.AsSlice()),
Zone: ip.Zone(),
}
// Use the unique node.Name field as the packet data to reduce the
@ -1478,8 +1480,8 @@ func (rs *reportState) runProbe(ctx context.Context, dm *tailcfg.DERPMap, probe
return
}
addr := c.nodeAddr(ctx, node, probe.proto)
if !addr.IsValid() {
addr, ok := c.nodeAddrPort(ctx, node, node.STUNPort, probe.proto)
if !ok {
c.logf("netcheck.runProbe: named node %q has no %v address", probe.node, probe.proto)
return
}
@ -1528,12 +1530,17 @@ func (rs *reportState) runProbe(ctx context.Context, dm *tailcfg.DERPMap, probe
c.vlogf("sent to %v", addr)
}
// proto is 4 or 6
// If it returns nil, the node is skipped.
func (c *Client) nodeAddr(ctx context.Context, n *tailcfg.DERPNode, proto probeProto) (ap netip.AddrPort) {
port := cmp.Or(n.STUNPort, 3478)
// nodeAddrPort returns the IP:port to send a STUN queries to for a given node.
//
// The provided port should be n.STUNPort, which may be negative to disable STUN.
// If STUN is disabled for this node, it returns ok=false.
// The port parameter is separate for the ICMP caller to provide a fake value.
//
// proto is [probeIPv4] or [probeIPv6].
func (c *Client) nodeAddrPort(ctx context.Context, n *tailcfg.DERPNode, port int, proto probeProto) (_ netip.AddrPort, ok bool) {
var zero netip.AddrPort
if port < 0 || port > 1<<16-1 {
return
return zero, false
}
if n.STUNTestIP != "" {
ip, err := netip.ParseAddr(n.STUNTestIP)
@ -1546,7 +1553,7 @@ func (c *Client) nodeAddr(ctx context.Context, n *tailcfg.DERPNode, proto probeP
if proto == probeIPv6 && ip.Is4() {
return
}
return netip.AddrPortFrom(ip, uint16(port))
return netip.AddrPortFrom(ip, uint16(port)), true
}
switch proto {
@ -1554,20 +1561,20 @@ func (c *Client) nodeAddr(ctx context.Context, n *tailcfg.DERPNode, proto probeP
if n.IPv4 != "" {
ip, _ := netip.ParseAddr(n.IPv4)
if !ip.Is4() {
return
return zero, false
}
return netip.AddrPortFrom(ip, uint16(port))
return netip.AddrPortFrom(ip, uint16(port)), true
}
case probeIPv6:
if n.IPv6 != "" {
ip, _ := netip.ParseAddr(n.IPv6)
if !ip.Is6() {
return
return zero, false
}
return netip.AddrPortFrom(ip, uint16(port))
return netip.AddrPortFrom(ip, uint16(port)), true
}
default:
return
return zero, false
}
// The default lookup function if we don't set UseDNSCache is to use net.DefaultResolver.
@ -1609,13 +1616,13 @@ func (c *Client) nodeAddr(ctx context.Context, n *tailcfg.DERPNode, proto probeP
addrs, err := lookupIPAddr(ctx, n.HostName)
for _, a := range addrs {
if (a.Is4() && probeIsV4) || (a.Is6() && !probeIsV4) {
return netip.AddrPortFrom(a, uint16(port))
return netip.AddrPortFrom(a, uint16(port)), true
}
}
if err != nil {
c.logf("netcheck: DNS lookup error for %q (node %q region %v): %v", n.HostName, n.Name, n.RegionID, err)
}
return
return zero, false
}
func regionHasDERPNode(r *tailcfg.DERPRegion) bool {

12
net/netcheck/netcheck_test.go
View File

@ -887,8 +887,8 @@ func TestNodeAddrResolve(t *testing.T) {
c.UseDNSCache = tt
t.Run("IPv4", func(t *testing.T) {
ap := c.nodeAddr(ctx, dn, probeIPv4)
if !ap.IsValid() {
ap, ok := c.nodeAddrPort(ctx, dn, dn.STUNPort, probeIPv4)
if !ok {
t.Fatal("expected valid AddrPort")
}
if !ap.Addr().Is4() {
@ -902,8 +902,8 @@ func TestNodeAddrResolve(t *testing.T) {
t.Skipf("IPv6 may not work on this machine")
}
ap := c.nodeAddr(ctx, dn, probeIPv6)
if !ap.IsValid() {
ap, ok := c.nodeAddrPort(ctx, dn, dn.STUNPort, probeIPv6)
if !ok {
t.Fatal("expected valid AddrPort")
}
if !ap.Addr().Is6() {
@ -912,8 +912,8 @@ func TestNodeAddrResolve(t *testing.T) {
t.Logf("got IPv6 addr: %v", ap)
})
t.Run("IPv6 Failure", func(t *testing.T) {
ap := c.nodeAddr(ctx, dnV4Only, probeIPv6)
if ap.IsValid() {
ap, ok := c.nodeAddrPort(ctx, dnV4Only, dn.STUNPort, probeIPv6)
if ok {
t.Fatalf("expected no addr but got: %v", ap)
}
t.Logf("correctly got invalid addr")