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Code Releases Activity

net: treat a nil *Resolver as a zero one, as documented

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Add accessors that handle nil without crashing.

Fixes #24330

Change-Id: If5fbbb6015ca8d65f620a06bad6e52de8cd896ad
Reviewed-on: https://go-review.googlesource.com/101315
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com>
This commit is contained in:
Brad Fitzpatrick 2018-03-19 09:16:25 +03:00
parent 5a4e09837c
commit 5c3cb64b2e
6 changed files with 37 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
src/net/conf.go
View File

@ -126,7 +126,7 @@ func (c *conf) hostLookupOrder(r *Resolver, hostname string) (ret hostLookupOrde
}()
}
fallbackOrder := hostLookupCgo
if c.netGo || (r != nil && r.PreferGo) {
if c.netGo || r.preferGo() {
fallbackOrder = hostLookupFilesDNS
}
if c.forceCgoLookupHost || c.resolv.unknownOpt || c.goos == "android" {

4
src/net/dnsclient_unix.go
View File

@ -377,7 +377,7 @@ func (r *Resolver) lookup(ctx context.Context, name string, qtype dnsmessage.Typ
if err == nil {
break
}
if nerr, ok := err.(Error); ok && nerr.Temporary() && r.StrictErrors {
if nerr, ok := err.(Error); ok && nerr.Temporary() && r.strictErrors() {
// If we hit a temporary error with StrictErrors enabled,
// stop immediately instead of trying more names.
break
@ -565,7 +565,7 @@ func (r *Resolver) goLookupIPCNAMEOrder(ctx context.Context, name string, order
for range qtypes {
racer := <-lane
if racer.error != nil {
if nerr, ok := racer.error.(Error); ok && nerr.Temporary() && r.StrictErrors {
if nerr, ok := racer.error.(Error); ok && nerr.Temporary() && r.strictErrors() {
// This error will abort the nameList loop.
hitStrictError = true
lastErr = racer.error

3
src/net/lookup.go
View File

@ -137,6 +137,9 @@ type Resolver struct {
// TODO(bradfitz): Timeout time.Duration?
}
func (r *Resolver) preferGo() bool { return r != nil && r.PreferGo }
func (r *Resolver) strictErrors() bool { return r != nil && r.StrictErrors }
// LookupHost looks up the given host using the local resolver.
// It returns a slice of that host's addresses.
func LookupHost(host string) (addrs []string, err error) {

24
src/net/lookup_test.go
View File

@ -814,3 +814,27 @@ func TestLookupContextCancel(t *testing.T) {
t.Fatal(err)
}
}
// Issue 24330: treat the nil *Resolver like a zero value. Verify nothing
// crashes if nil is used.
func TestNilResolverLookup(t *testing.T) {
if testenv.Builder() == "" {
testenv.MustHaveExternalNetwork(t)
}
if runtime.GOOS == "nacl" {
t.Skip("skip on nacl")
}
var r *Resolver = nil
ctx := context.Background()
// Don't care about the results, just that nothing panics:
r.LookupAddr(ctx, "8.8.8.8")
r.LookupCNAME(ctx, "google.com")
r.LookupHost(ctx, "google.com")
r.LookupIPAddr(ctx, "google.com")
r.LookupMX(ctx, "gmail.com")
r.LookupNS(ctx, "google.com")
r.LookupPort(ctx, "tcp", "smtp")
r.LookupSRV(ctx, "service", "proto", "name")
r.LookupTXT(ctx, "gmail.com")
}

12
src/net/lookup_unix.go
View File

@ -61,7 +61,7 @@ func (r *Resolver) dial(ctx context.Context, network, server string) (Conn, erro
// addresses, which Dial will use without a DNS lookup.
var c Conn
var err error
if r.Dial != nil {
if r != nil && r.Dial != nil {
c, err = r.Dial(ctx, network, server)
} else {
var d Dialer
@ -75,7 +75,7 @@ func (r *Resolver) dial(ctx context.Context, network, server string) (Conn, erro
func (r *Resolver) lookupHost(ctx context.Context, host string) (addrs []string, err error) {
order := systemConf().hostLookupOrder(r, host)
if !r.PreferGo && order == hostLookupCgo {
if !r.preferGo() && order == hostLookupCgo {
if addrs, err, ok := cgoLookupHost(ctx, host); ok {
return addrs, err
}
@ -86,7 +86,7 @@ func (r *Resolver) lookupHost(ctx context.Context, host string) (addrs []string,
}
func (r *Resolver) lookupIP(ctx context.Context, host string) (addrs []IPAddr, err error) {
if r.PreferGo {
if r.preferGo() {
return r.goLookupIP(ctx, host)
}
order := systemConf().hostLookupOrder(r, host)
@ -102,7 +102,7 @@ func (r *Resolver) lookupIP(ctx context.Context, host string) (addrs []IPAddr, e
}
func (r *Resolver) lookupPort(ctx context.Context, network, service string) (int, error) {
if !r.PreferGo && systemConf().canUseCgo() {
if !r.preferGo() && systemConf().canUseCgo() {
if port, err, ok := cgoLookupPort(ctx, network, service); ok {
if err != nil {
// Issue 18213: if cgo fails, first check to see whether we
@ -118,7 +118,7 @@ func (r *Resolver) lookupPort(ctx context.Context, network, service string) (int
}
func (r *Resolver) lookupCNAME(ctx context.Context, name string) (string, error) {
if !r.PreferGo && systemConf().canUseCgo() {
if !r.preferGo() && systemConf().canUseCgo() {
if cname, err, ok := cgoLookupCNAME(ctx, name); ok {
return cname, err
}
@ -308,7 +308,7 @@ func (r *Resolver) lookupTXT(ctx context.Context, name string) ([]string, error)
}
func (r *Resolver) lookupAddr(ctx context.Context, addr string) ([]string, error) {
if !r.PreferGo && systemConf().canUseCgo() {
if !r.preferGo() && systemConf().canUseCgo() {
if ptrs, err, ok := cgoLookupPTR(ctx, addr); ok {
return ptrs, err
}

2
src/net/lookup_windows.go
View File

@ -136,7 +136,7 @@ func (r *Resolver) lookupIP(ctx context.Context, name string) ([]IPAddr, error)
}
func (r *Resolver) lookupPort(ctx context.Context, network, service string) (int, error) {
if r.PreferGo {
if r.preferGo() {
return lookupPortMap(network, service)
}