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net/portmapper: relax source port check for UPnP responses

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Per a packet capture provided, some gateways will reply to a UPnP
discovery packet with a UDP packet with a source port that does not come
from the UPnP port. Accept these packets with a log message.

Updates #7377

Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I5d4d5b2a0275009ed60f15c20b484fe2025d094b
This commit is contained in:
Andrew Dunham 2023-03-04 00:23:26 -05:00
parent 51eb0b2cb7
commit f6cd24499b
1 changed files with 41 additions and 22 deletions
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63
net/portmapper/portmapper.go
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@ -805,33 +805,48 @@ func (c *Client) Probe(ctx context.Context) (res ProbeResult, err error) {
continue
}
ip = ip.Unmap()
handleUPnPResponse := func() {
metricUPnPResponse.Add(1)
if ip != gw {
// https://github.com/tailscale/tailscale/issues/5502
c.logf("UPnP discovery response from %v, but gateway IP is %v", ip, gw)
}
meta, err := parseUPnPDiscoResponse(buf[:n])
if err != nil {
metricUPnPParseErr.Add(1)
c.logf("unrecognized UPnP discovery response; ignoring: %v", err)
return
}
metricUPnPOK.Add(1)
c.logf("[v1] UPnP reply %+v, %q", meta, buf[:n])
res.UPnP = true
c.mu.Lock()
c.uPnPSawTime = time.Now()
if c.uPnPMeta != meta {
c.logf("UPnP meta changed: %+v", meta)
c.uPnPMeta = meta
metricUPnPUpdatedMeta.Add(1)
}
c.mu.Unlock()
}
port := uint16(addr.(*net.UDPAddr).Port)
switch port {
case c.upnpPort():
metricUPnPResponse.Add(1)
if mem.Contains(mem.B(buf[:n]), mem.S(":InternetGatewayDevice:")) {
if ip != gw {
// https://github.com/tailscale/tailscale/issues/5502
c.logf("UPnP discovery response from %v, but gateway IP is %v", ip, gw)
}
meta, err := parseUPnPDiscoResponse(buf[:n])
if err != nil {
metricUPnPParseErr.Add(1)
c.logf("unrecognized UPnP discovery response; ignoring: %v", err)
continue
}
metricUPnPOK.Add(1)
c.logf("[v1] UPnP reply %+v, %q", meta, buf[:n])
res.UPnP = true
c.mu.Lock()
c.uPnPSawTime = time.Now()
if c.uPnPMeta != meta {
c.logf("UPnP meta changed: %+v", meta)
c.uPnPMeta = meta
metricUPnPUpdatedMeta.Add(1)
}
c.mu.Unlock()
handleUPnPResponse()
}
default:
// https://github.com/tailscale/tailscale/issues/7377
if mem.Contains(mem.B(buf[:n]), mem.S(":InternetGatewayDevice:")) {
c.logf("UPnP discovery response from non-UPnP port %d", port)
metricUPnPResponseAlternatePort.Add(1)
handleUPnPResponse()
}
case c.pxpPort(): // same value for PMP and PCP
metricPXPResponse.Add(1)
if pres, ok := parsePCPResponse(buf[:n]); ok {
@ -983,6 +998,10 @@ func (c *Client) Probe(ctx context.Context) (res ProbeResult, err error) {
// metricUPnPResponse counts the number of times we received a UPnP response.
metricUPnPResponse = clientmetric.NewCounter("portmap_upnp_response")
// metricUPnPResponseAlternatePort counts the number of times we
// received a UPnP response from a port other than the UPnP port.
metricUPnPResponseAlternatePort = clientmetric.NewCounter("portmap_upnp_response_alternate_port")
// metricUPnPParseErr counts the number of times we failed to parse a UPnP response.
metricUPnPParseErr = clientmetric.NewCounter("portmap_upnp_parse_err")