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net/dnsfallback: allow setting log function (#5550)

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This broke a test in corp that enforces we don't use the log package.

Signed-off-by: Andrew Dunham <andrew@tailscale.com>
This commit is contained in:
Andrew Dunham 2022-09-06 11:19:50 -04:00 committed by GitHub
parent b8596f2a2f
commit f52a659076
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GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 38 additions and 10 deletions
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38
net/dnsfallback/dnsfallback.go
View File

@ -29,7 +29,9 @@ import (
"tailscale.com/net/netns"
"tailscale.com/net/tlsdial"
"tailscale.com/net/tshttpproxy"
"tailscale.com/syncs"
"tailscale.com/tailcfg"
"tailscale.com/types/logger"
)
func Lookup(ctx context.Context, host string) ([]netip.Addr, error) {
@ -77,16 +79,16 @@ func Lookup(ctx context.Context, host string) ([]netip.Addr, error) {
if err := ctx.Err(); err != nil {
return nil, err
}
log.Printf("trying bootstrapDNS(%q, %q) for %q ...", cand.dnsName, cand.ip, host)
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)
if err != nil {
log.Printf("bootstrapDNS(%q, %q) for %q error: %v", cand.dnsName, cand.ip, host, err)
logf("bootstrapDNS(%q, %q) for %q error: %v", cand.dnsName, cand.ip, host, err)
continue
}
if ips := dm[host]; len(ips) > 0 {
log.Printf("bootstrapDNS(%q, %q) for %q = %v", cand.dnsName, cand.ip, host, ips)
logf("bootstrapDNS(%q, %q) for %q = %v", cand.dnsName, cand.ip, host, ips)
return ips, nil
}
}
@ -99,7 +101,7 @@ 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) {
dialer := netns.NewDialer(log.Printf)
dialer := netns.NewDialer(logf)
tr := http.DefaultTransport.(*http.Transport).Clone()
tr.Proxy = tshttpproxy.ProxyFromEnvironment
tr.DialContext = func(ctx context.Context, netw, addr string) (net.Conn, error) {
@ -201,7 +203,7 @@ func UpdateCache(c *tailcfg.DERPMap) {
d, err := json.Marshal(c)
if err != nil {
log.Printf("[v1] dnsfallback: UpdateCache error marshaling: %v", err)
logf("[v1] dnsfallback: UpdateCache error marshaling: %v", err)
return
}
@ -213,11 +215,10 @@ func UpdateCache(c *tailcfg.DERPMap) {
if cachePath != "" {
err = atomicfile.WriteFile(cachePath, d, 0600)
if err != nil {
log.Printf("[v1] dnsfallback: UpdateCache error writing: %v", err)
logf("[v1] dnsfallback: UpdateCache error writing: %v", err)
return
}
}
log.Printf("[v2] dnsfallback: UpdateCache succeeded")
}
// SetCachePath sets the path to the on-disk DERP map cache that we store and
@ -231,17 +232,34 @@ func SetCachePath(path string) {
f, err := os.Open(path)
if err != nil {
log.Printf("[v1] dnsfallback: SetCachePath error reading %q: %v", path, err)
logf("[v1] dnsfallback: SetCachePath error reading %q: %v", path, err)
return
}
defer f.Close()
dm := new(tailcfg.DERPMap)
if err := json.NewDecoder(f).Decode(dm); err != nil {
log.Printf("[v1] dnsfallback: SetCachePath error decoding %q: %v", path, err)
logf("[v1] dnsfallback: SetCachePath error decoding %q: %v", path, err)
return
}
cachedDERPMap.Store(dm)
log.Printf("[v2] dnsfallback: SetCachePath loaded cached DERP map")
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. The default
// logger if this function is not called is 'log.Printf'.
func SetLogger(log logger.Logf) {
logfunc.Store(log)
}
func logf(format string, args ...any) {
if lf := logfunc.Load(); lf != nil {
lf(format, args...)
} else {
log.Printf(format, args...)
}
}

10
net/dnsfallback/dnsfallback_test.go
View File

@ -25,6 +25,11 @@ 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
@ -101,6 +106,11 @@ 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