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net/dnsfallback: more explicitly pass through logf function

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Redoes the approach from #5550 and #7539 to explicitly pass in the logf
function, instead of having global state that can be overridden.

Signed-off-by: Mihai Parparita <mihai@tailscale.com>
pull/7904/head
Mihai Parparita 2 years ago committed by Mihai Parparita
parent 28cb1221ba
commit 9a655a1d58
8 changed files with 20 additions and 66 deletions
Show Stats Download Patch File Download Diff File

2
cmd/tailscaled/tailscaled.go
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@ -534,7 +534,7 @@ func getLocalBackend(ctx context.Context, logf logger.Logf, logID logid.PublicID
lb.SetLogFlusher(logPol.Logtail.StartFlush)
}
if root := lb.TailscaleVarRoot(); root != "" {
dnsfallback.SetCachePath(filepath.Join(root, "derpmap.cached.json"))
dnsfallback.SetCachePath(filepath.Join(root, "derpmap.cached.json"), logf)
}
lb.SetDecompressor(func() (controlclient.Decompressor, error) {
return smallzstd.NewDecoder(nil)

2
control/controlclient/direct.go
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@ -211,7 +211,7 @@ func NewDirect(opts Options) (*Direct, error) {
dnsCache := &dnscache.Resolver{
Forward: dnscache.Get().Forward, // use default cache's forwarder
UseLastGood: true,
LookupIPFallback: dnsfallback.Lookup,
LookupIPFallback: dnsfallback.Lookup(opts.Logf),
Logf: opts.Logf,
}
tr := http.DefaultTransport.(*http.Transport).Clone()

2
control/controlhttp/client.go
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@ -393,7 +393,7 @@ func (a *Dialer) tryURLUpgrade(ctx context.Context, u *url.URL, addr netip.Addr,
} else {
dns = &dnscache.Resolver{
Forward: dnscache.Get().Forward,
LookupIPFallback: dnsfallback.Lookup,
LookupIPFallback: dnsfallback.Lookup(a.logf),
UseLastGood: true,
Logf: a.Logf, // not a.logf method; we want to propagate nil-ness
}

2
ipn/ipnlocal/local.go
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@ -1077,7 +1077,7 @@ func (b *LocalBackend) setClientStatus(st controlclient.Status) {
b.e.SetDERPMap(st.NetMap.DERPMap)
// Update our cached DERP map
dnsfallback.UpdateCache(st.NetMap.DERPMap)
dnsfallback.UpdateCache(st.NetMap.DERPMap, b.logf)
b.send(ipn.Notify{NetMap: st.NetMap})
}

2
logpolicy/logpolicy.go
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@ -711,7 +711,7 @@ func DialContext(ctx context.Context, netw, addr string) (net.Conn, error) {
dnsCache := &dnscache.Resolver{
Forward: dnscache.Get().Forward, // use default cache's forwarder
UseLastGood: true,
LookupIPFallback: dnsfallback.Lookup,
LookupIPFallback: dnsfallback.Lookup(log.Printf),
}
dialer := dnscache.Dialer(nd.DialContext, dnsCache)
c, err = dialer(ctx, netw, addr)

38
net/dnsfallback/dnsfallback.go
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@ -13,7 +13,6 @@ import (
"encoding/json"
"errors"
"fmt"
"log"
"net"
"net/http"
"net/netip"
@ -27,13 +26,18 @@ import (
"tailscale.com/net/netns"
"tailscale.com/net/tlsdial"
"tailscale.com/net/tshttpproxy"
"tailscale.com/syncs"
"tailscale.com/tailcfg"
"tailscale.com/types/logger"
"tailscale.com/util/slicesx"
)
func Lookup(ctx context.Context, host string) ([]netip.Addr, error) {
func Lookup(logf logger.Logf) func(ctx context.Context, host string) ([]netip.Addr, error) {
return func(ctx context.Context, host string) ([]netip.Addr, error) {
return lookup(ctx, host, logf)
}
}
func lookup(ctx context.Context, host string, logf logger.Logf) ([]netip.Addr, error) {
if ip, err := netip.ParseAddr(host); err == nil && ip.IsValid() {
return []netip.Addr{ip}, nil
}
@ -81,7 +85,7 @@ func Lookup(ctx context.Context, host string) ([]netip.Addr, error) {
logf("trying bootstrapDNS(%q, %q) for %q ...", cand.dnsName, cand.ip, host)
ctx, cancel := context.WithTimeout(ctx, 3*time.Second)
defer cancel()
dm, err := bootstrapDNSMap(ctx, cand.dnsName, cand.ip, host)
dm, err := bootstrapDNSMap(ctx, cand.dnsName, cand.ip, host, logf)
if err != nil {
logf("bootstrapDNS(%q, %q) for %q error: %v", cand.dnsName, cand.ip, host, err)
continue
@ -100,7 +104,7 @@ func Lookup(ctx context.Context, host string) ([]netip.Addr, error) {
// serverName and serverIP of are, say, "derpN.tailscale.com".
// queryName is the name being sought (e.g. "controlplane.tailscale.com"), passed as hint.
func bootstrapDNSMap(ctx context.Context, serverName string, serverIP netip.Addr, queryName string) (dnsMap, error) {
func bootstrapDNSMap(ctx context.Context, serverName string, serverIP netip.Addr, queryName string, logf logger.Logf) (dnsMap, error) {
dialer := netns.NewDialer(logf)
tr := http.DefaultTransport.(*http.Transport).Clone()
tr.Proxy = tshttpproxy.ProxyFromEnvironment
@ -194,7 +198,7 @@ var cachePath string
// UpdateCache stores the DERP map cache back to disk.
//
// The caller must not mutate 'c' after calling this function.
func UpdateCache(c *tailcfg.DERPMap) {
func UpdateCache(c *tailcfg.DERPMap, logf logger.Logf) {
// Don't do anything if nothing changed.
curr := cachedDERPMap.Load()
if reflect.DeepEqual(curr, c) {
@ -227,7 +231,7 @@ func UpdateCache(c *tailcfg.DERPMap) {
//
// This function should be called before any calls to UpdateCache, as it is not
// concurrency-safe.
func SetCachePath(path string) {
func SetCachePath(path string, logf logger.Logf) {
cachePath = path
f, err := os.Open(path)
@ -246,23 +250,3 @@ func SetCachePath(path string) {
cachedDERPMap.Store(dm)
logf("[v2] dnsfallback: SetCachePath loaded cached DERP map")
}
// logfunc stores the logging function to use for this package.
var logfunc syncs.AtomicValue[logger.Logf]
// SetLogger sets the logging function that this package will use, and returns
// the old value (which may be nil).
//
// If this function is never called, or if this function is called with a nil
// value, 'log.Printf' will be used to print logs.
func SetLogger(log logger.Logf) (old logger.Logf) {
return logfunc.Swap(log)
}
func logf(format string, args ...any) {
if lf := logfunc.Load(); lf != nil {
lf(format, args...)
} else {
log.Printf(format, args...)
}
}

18
net/dnsfallback/dnsfallback_test.go
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@ -24,11 +24,6 @@ func TestGetDERPMap(t *testing.T) {
}
func TestCache(t *testing.T) {
oldlog := logfunc.Load()
SetLogger(t.Logf)
t.Cleanup(func() {
SetLogger(oldlog)
})
cacheFile := filepath.Join(t.TempDir(), "cache.json")
// Write initial cache value
@ -73,7 +68,7 @@ func TestCache(t *testing.T) {
cachedDERPMap.Store(nil)
// Load the cache
SetCachePath(cacheFile)
SetCachePath(cacheFile, t.Logf)
if cm := cachedDERPMap.Load(); !reflect.DeepEqual(initialCache, cm) {
t.Fatalf("cached map was %+v; want %+v", cm, initialCache)
}
@ -105,11 +100,6 @@ func TestCache(t *testing.T) {
}
func TestCacheUnchanged(t *testing.T) {
oldlog := logfunc.Load()
SetLogger(t.Logf)
t.Cleanup(func() {
SetLogger(oldlog)
})
cacheFile := filepath.Join(t.TempDir(), "cache.json")
// Write initial cache value
@ -140,7 +130,7 @@ func TestCacheUnchanged(t *testing.T) {
cachedDERPMap.Store(nil)
// Load the cache
SetCachePath(cacheFile)
SetCachePath(cacheFile, t.Logf)
if cm := cachedDERPMap.Load(); !reflect.DeepEqual(initialCache, cm) {
t.Fatalf("cached map was %+v; want %+v", cm, initialCache)
}
@ -152,7 +142,7 @@ func TestCacheUnchanged(t *testing.T) {
t.Fatal(err)
}
UpdateCache(initialCache)
UpdateCache(initialCache, t.Logf)
if _, err := os.Stat(cacheFile); !os.IsNotExist(err) {
t.Fatalf("got err=%v; expected to not find cache file", err)
}
@ -173,7 +163,7 @@ func TestCacheUnchanged(t *testing.T) {
clonedNode.IPv4 = "1.2.3.5"
updatedCache.Regions[99].Nodes = append(updatedCache.Regions[99].Nodes, &clonedNode)
UpdateCache(updatedCache)
UpdateCache(updatedCache, t.Logf)
if st, err := os.Stat(cacheFile); err != nil {
t.Fatalf("could not stat cache file; err=%v", err)
} else if !st.Mode().IsRegular() || st.Size() == 0 {

20
tsnet/tsnet.go
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@ -41,7 +41,6 @@ import (
"tailscale.com/logpolicy"
"tailscale.com/logtail"
"tailscale.com/logtail/filch"
"tailscale.com/net/dnsfallback"
"tailscale.com/net/memnet"
"tailscale.com/net/proxymux"
"tailscale.com/net/socks5"
@ -651,25 +650,6 @@ func (s *Server) logf(format string, a ...interface{}) {
log.Printf(format, a...)
}
// ReplaceGlobalLoggers will replace any Tailscale-specific package-global
// loggers with this Server's logger. It returns a function that, when called,
// will undo any changes made.
//
// Note that calling this function from multiple Servers will result in the
// last call taking all logs; logs are not duplicated.
func (s *Server) ReplaceGlobalLoggers() (undo func()) {
var undos []func()
oldDnsFallback := dnsfallback.SetLogger(s.logf)
undos = append(undos, func() { dnsfallback.SetLogger(oldDnsFallback) })
return func() {
for _, fn := range undos {
fn()
}
}
}
// printAuthURLLoop loops once every few seconds while the server is still running and
// is in NeedsLogin state, printing out the auth URL.
func (s *Server) printAuthURLLoop() {

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