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tailscale/wgengine/magicsock/debugknobs.go

98 lines
4.1 KiB
Go

// Copyright (c) Tailscale Inc & AUTHORS
// SPDX-License-Identifier: BSD-3-Clause
//go:build !ios && !js
package magicsock
import (
"log"
"net/netip"
"strings"
"sync"
"tailscale.com/envknob"
)
// Various debugging and experimental tweakables, set by environment
// variable.
var (
// debugDisco prints verbose logs of active discovery events as
// they happen.
debugDisco = envknob.RegisterBool("TS_DEBUG_DISCO")
// debugPeerMap prints verbose logs of changes to the peermap.
debugPeerMap = envknob.RegisterBool("TS_DEBUG_MAGICSOCK_PEERMAP")
// debugOmitLocalAddresses removes all local interface addresses
// from magicsock's discovered local endpoints. Used in some tests.
debugOmitLocalAddresses = envknob.RegisterBool("TS_DEBUG_OMIT_LOCAL_ADDRS")
// logDerpVerbose logs all received DERP packets, including their
// full payload.
logDerpVerbose = envknob.RegisterBool("TS_DEBUG_DERP")
// debugReSTUNStopOnIdle unconditionally enables the "shut down
// STUN if magicsock is idle" behavior that normally only triggers
// on mobile devices, lowers the shutdown interval, and logs more
// verbosely about idle measurements.
debugReSTUNStopOnIdle = envknob.RegisterBool("TS_DEBUG_RESTUN_STOP_ON_IDLE")
// debugAlwaysDERP disables the use of UDP, forcing all peer communication over DERP.
debugAlwaysDERP = envknob.RegisterBool("TS_DEBUG_ALWAYS_USE_DERP")
// debugDERPAddr sets the derp address manually, overriding the DERP map from control.
debugUseDERPAddr = envknob.RegisterString("TS_DEBUG_USE_DERP_ADDR")
// debugDERPUseHTTP tells clients to connect to DERP via HTTP on port 3340 instead of
// HTTPS on 443.
debugUseDERPHTTP = envknob.RegisterBool("TS_DEBUG_USE_DERP_HTTP")
// debugEnableSilentDisco disables the use of heartbeatTimer on the endpoint struct
// and attempts to handle disco silently. See issue #540 for details.
debugEnableSilentDisco = envknob.RegisterBool("TS_DEBUG_ENABLE_SILENT_DISCO")
// debugSendCallMeUnknownPeer sends a CallMeMaybe to a non-existent destination every
// time we send a real CallMeMaybe to test the PeerGoneNotHere logic.
debugSendCallMeUnknownPeer = envknob.RegisterBool("TS_DEBUG_SEND_CALLME_UNKNOWN_PEER")
// debugBindSocket prints extra debugging about socket rebinding in magicsock.
debugBindSocket = envknob.RegisterBool("TS_DEBUG_MAGICSOCK_BIND_SOCKET")
// debugRingBufferMaxSizeBytes overrides the default size of the endpoint
// history ringbuffer.
debugRingBufferMaxSizeBytes = envknob.RegisterInt("TS_DEBUG_MAGICSOCK_RING_BUFFER_MAX_SIZE_BYTES")
// debugEnablePMTUD enables the peer MTU feature, which does path MTU
// discovery on UDP connections between peers. Currently (2023-09-05)
// this only turns on the don't fragment bit for the magicsock UDP
// sockets.
//
//lint:ignore U1000 used on Linux/Darwin only
debugEnablePMTUD = envknob.RegisterOptBool("TS_DEBUG_ENABLE_PMTUD")
// debugPMTUD prints extra debugging about peer MTU path discovery.
//
//lint:ignore U1000 used on Linux/Darwin only
debugPMTUD = envknob.RegisterBool("TS_DEBUG_PMTUD")
// Hey you! Adding a new debugknob? Make sure to stub it out in the
// debugknobs_stubs.go file too.
)
// inTest reports whether the running program is a test that set the
// IN_TS_TEST environment variable.
//
// Unlike the other debug tweakables above, this one needs to be
// checked every time at runtime, because tests set this after program
// startup.
func inTest() bool { return envknob.Bool("IN_TS_TEST") }
// pretendpoints returns TS_DEBUG_PRETENDPOINT as []AddrPort, if set.
// See https://github.com/tailscale/tailscale/issues/12578 and
// https://github.com/tailscale/tailscale/pull/12735.
//
// It can be between 0 and 3 comma-separated AddrPorts.
var pretendpoints = sync.OnceValue(func() (ret []netip.AddrPort) {
all := envknob.String("TS_DEBUG_PRETENDPOINT")
const max = 3
remain := all
for remain != "" && len(ret) < max {
var s string
s, remain, _ = strings.Cut(remain, ",")
ap, err := netip.ParseAddrPort(s)
if err != nil {
log.Printf("ignoring invalid AddrPort %q in TS_DEBUG_PRETENDPOINT %q: %v", s, all, err)
continue
}
ret = append(ret, ap)
}
return
})