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net: make go resolver aware of network parameter

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Currently, the go resolver always send two DNS queries (A and AAAA) even
if tcp4/udp4/ip4 or tcp6/udp6/ip6 is used. This can cause unwanted
latencies when making IPv4-only or IPv6-only connections.

This change make go resolver aware of network parameter. Now, only one A
query is sent when tcp4/udp4/ip4 is used, and vice versa for
tcp6/udp6/ip6.

Fixes #45024

Change-Id: I815f909e6df5f7242cfc900f7dfecca628c3a2c8
GitHub-Last-Rev: 3d30c486de
GitHub-Pull-Request: golang/go#45016
Reviewed-on: https://go-review.googlesource.com/c/go/+/301709
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Trust: Emmanuel Odeke <emmanuel@orijtech.com>
This commit is contained in:
Zhang Boyang 2021-03-15 15:27:51 +00:00 committed by Emmanuel Odeke
parent f4b918384d
commit 53dd0d7809
4 changed files with 17 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
src/net/dnsclient_unix.go
View File

@ -532,7 +532,7 @@ func (r *Resolver) goLookupHostOrder(ctx context.Context, name string, order hos
return
}
}
ips, _, err := r.goLookupIPCNAMEOrder(ctx, name, order)
ips, _, err := r.goLookupIPCNAMEOrder(ctx, "ip", name, order)
if err != nil {
return
}
@ -558,13 +558,13 @@ func goLookupIPFiles(name string) (addrs []IPAddr) {
// goLookupIP is the native Go implementation of LookupIP.
// The libc versions are in cgo_*.go.
func (r *Resolver) goLookupIP(ctx context.Context, host string) (addrs []IPAddr, err error) {
func (r *Resolver) goLookupIP(ctx context.Context, network, host string) (addrs []IPAddr, err error) {
order := systemConf().hostLookupOrder(r, host)
addrs, _, err = r.goLookupIPCNAMEOrder(ctx, host, order)
addrs, _, err = r.goLookupIPCNAMEOrder(ctx, network, host, order)
return
}
func (r *Resolver) goLookupIPCNAMEOrder(ctx context.Context, name string, order hostLookupOrder) (addrs []IPAddr, cname dnsmessage.Name, err error) {
func (r *Resolver) goLookupIPCNAMEOrder(ctx context.Context, network, name string, order hostLookupOrder) (addrs []IPAddr, cname dnsmessage.Name, err error) {
if order == hostLookupFilesDNS || order == hostLookupFiles {
addrs = goLookupIPFiles(name)
if len(addrs) > 0 || order == hostLookupFiles {
@ -585,7 +585,13 @@ func (r *Resolver) goLookupIPCNAMEOrder(ctx context.Context, name string, order
error
}
lane := make(chan result, 1)
qtypes := [...]dnsmessage.Type{dnsmessage.TypeA, dnsmessage.TypeAAAA}
qtypes := []dnsmessage.Type{dnsmessage.TypeA, dnsmessage.TypeAAAA}
switch ipVersion(network) {
case '4':
qtypes = []dnsmessage.Type{dnsmessage.TypeA}
case '6':
qtypes = []dnsmessage.Type{dnsmessage.TypeAAAA}
}
var queryFn func(fqdn string, qtype dnsmessage.Type)
var responseFn func(fqdn string, qtype dnsmessage.Type) result
if conf.singleRequest {
@ -730,7 +736,7 @@ func (r *Resolver) goLookupIPCNAMEOrder(ctx context.Context, name string, order
// goLookupCNAME is the native Go (non-cgo) implementation of LookupCNAME.
func (r *Resolver) goLookupCNAME(ctx context.Context, host string) (string, error) {
order := systemConf().hostLookupOrder(r, host)
_, cname, err := r.goLookupIPCNAMEOrder(ctx, host, order)
_, cname, err := r.goLookupIPCNAMEOrder(ctx, "ip", host, order)
return cname.String(), err
}

4
src/net/dnsclient_unix_test.go
View File

@ -601,14 +601,14 @@ func TestGoLookupIPOrderFallbackToFile(t *testing.T) {
name := fmt.Sprintf("order %v", order)
// First ensure that we get an error when contacting a non-existent host.
_, _, err := r.goLookupIPCNAMEOrder(context.Background(), "notarealhost", order)
_, _, err := r.goLookupIPCNAMEOrder(context.Background(), "ip", "notarealhost", order)
if err == nil {
t.Errorf("%s: expected error while looking up name not in hosts file", name)
continue
}
// Now check that we get an address when the name appears in the hosts file.
addrs, _, err := r.goLookupIPCNAMEOrder(context.Background(), "thor", order) // entry is in "testdata/hosts"
addrs, _, err := r.goLookupIPCNAMEOrder(context.Background(), "ip", "thor", order) // entry is in "testdata/hosts"
if err != nil {
t.Errorf("%s: expected to successfully lookup host entry", name)
continue

4
src/net/lookup_unix.go
View File

@ -90,7 +90,7 @@ func (r *Resolver) lookupHost(ctx context.Context, host string) (addrs []string,
func (r *Resolver) lookupIP(ctx context.Context, network, host string) (addrs []IPAddr, err error) {
if r.preferGo() {
return r.goLookupIP(ctx, host)
return r.goLookupIP(ctx, network, host)
}
order := systemConf().hostLookupOrder(r, host)
if order == hostLookupCgo {
@ -100,7 +100,7 @@ func (r *Resolver) lookupIP(ctx context.Context, network, host string) (addrs []
// cgo not available (or netgo); fall back to Go's DNS resolver
order = hostLookupFilesDNS
}
ips, _, err := r.goLookupIPCNAMEOrder(ctx, host, order)
ips, _, err := r.goLookupIPCNAMEOrder(ctx, network, host, order)
return ips, err
}

2
src/net/netgo_unix_test.go
View File

@ -24,7 +24,7 @@ func TestGoLookupIP(t *testing.T) {
if err != nil {
t.Error(err)
}
if _, err := DefaultResolver.goLookupIP(ctx, host); err != nil {
if _, err := DefaultResolver.goLookupIP(ctx, "ip", host); err != nil {
t.Error(err)
}
}