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net: make cgo resolver work more accurately with network parameter

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Unlike the go resolver, the existing cgo resolver exchanges both DNS A
and AAAA RR queries unconditionally and causes unreasonable connection
setup latencies to applications using the cgo resolver.

This change adds new argument (`network`) in all functions through the
series of calls: from Resolver.internetAddrList to cgoLookupIPCNAME.

Benefit: no redundant DNS calls if certain IP version is used IPv4/IPv6
(no `AAAA` DNS requests if used tcp4, udp4, ip4 network. And vice
versa: no `A` DNS requests if used tcp6, udp6, ip6 network)

Fixes #25947

Change-Id: I39edbd726d82d6133fdada4d06cd90d401e7e669
Reviewed-on: https://go-review.googlesource.com/c/120215
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
This commit is contained in:
Eugene Kalinin 2018-06-21 01:23:37 +03:00 committed by Brad Fitzpatrick
parent fc4f2e5692
commit c659be4dc8
15 changed files with 110 additions and 44 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
src/net/cgo_stub.go
View File

@ -24,7 +24,7 @@ func cgoLookupPort(ctx context.Context, network, service string) (port int, err
return 0, nil, false
}
func cgoLookupIP(ctx context.Context, name string) (addrs []IPAddr, err error, completed bool) {
func cgoLookupIP(ctx context.Context, network, name string) (addrs []IPAddr, err error, completed bool) {
return nil, nil, false
}

37
src/net/cgo_unix.go
View File

@ -49,7 +49,7 @@ type reverseLookupResult struct {
}
func cgoLookupHost(ctx context.Context, name string) (hosts []string, err error, completed bool) {
addrs, err, completed := cgoLookupIP(ctx, name)
addrs, err, completed := cgoLookupIP(ctx, "ip", name)
for _, addr := range addrs {
hosts = append(hosts, addr.String())
}
@ -69,13 +69,11 @@ func cgoLookupPort(ctx context.Context, network, service string) (port int, err
default:
return 0, &DNSError{Err: "unknown network", Name: network + "/" + service}, true
}
if len(network) >= 4 {
switch network[3] {
case '4':
hints.ai_family = C.AF_INET
case '6':
hints.ai_family = C.AF_INET6
}
switch ipVersion(network) {
case '4':
hints.ai_family = C.AF_INET
case '6':
hints.ai_family = C.AF_INET6
}
if ctx.Done() == nil {
port, err := cgoLookupServicePort(&hints, network, service)
@ -135,13 +133,20 @@ func cgoPortLookup(result chan<- portLookupResult, hints *C.struct_addrinfo, net
result <- portLookupResult{port, err}
}
func cgoLookupIPCNAME(name string) (addrs []IPAddr, cname string, err error) {
func cgoLookupIPCNAME(network, name string) (addrs []IPAddr, cname string, err error) {
acquireThread()
defer releaseThread()
var hints C.struct_addrinfo
hints.ai_flags = cgoAddrInfoFlags
hints.ai_socktype = C.SOCK_STREAM
hints.ai_family = C.AF_UNSPEC
switch ipVersion(network) {
case '4':
hints.ai_family = C.AF_INET
case '6':
hints.ai_family = C.AF_INET6
}
h := make([]byte, len(name)+1)
copy(h, name)
@ -197,18 +202,18 @@ func cgoLookupIPCNAME(name string) (addrs []IPAddr, cname string, err error) {
return addrs, cname, nil
}
func cgoIPLookup(result chan<- ipLookupResult, name string) {
addrs, cname, err := cgoLookupIPCNAME(name)
func cgoIPLookup(result chan<- ipLookupResult, network, name string) {
addrs, cname, err := cgoLookupIPCNAME(network, name)
result <- ipLookupResult{addrs, cname, err}
}
func cgoLookupIP(ctx context.Context, name string) (addrs []IPAddr, err error, completed bool) {
func cgoLookupIP(ctx context.Context, network, name string) (addrs []IPAddr, err error, completed bool) {
if ctx.Done() == nil {
addrs, _, err = cgoLookupIPCNAME(name)
addrs, _, err = cgoLookupIPCNAME(network, name)
return addrs, err, true
}
result := make(chan ipLookupResult, 1)
go cgoIPLookup(result, name)
go cgoIPLookup(result, network, name)
select {
case r := <-result:
return r.addrs, r.err, true
@ -219,11 +224,11 @@ func cgoLookupIP(ctx context.Context, name string) (addrs []IPAddr, err error, c
func cgoLookupCNAME(ctx context.Context, name string) (cname string, err error, completed bool) {
if ctx.Done() == nil {
_, cname, err = cgoLookupIPCNAME(name)
_, cname, err = cgoLookupIPCNAME("ip", name)
return cname, err, true
}
result := make(chan ipLookupResult, 1)
go cgoIPLookup(result, name)
go cgoIPLookup(result, "ip", name)
select {
case r := <-result:
return r.cname, r.err, true

4
src/net/cgo_unix_test.go
View File

@ -15,7 +15,7 @@ import (
func TestCgoLookupIP(t *testing.T) {
defer dnsWaitGroup.Wait()
ctx := context.Background()
_, err, ok := cgoLookupIP(ctx, "localhost")
_, err, ok := cgoLookupIP(ctx, "ip", "localhost")
if !ok {
t.Errorf("cgoLookupIP must not be a placeholder")
}
@ -28,7 +28,7 @@ func TestCgoLookupIPWithCancel(t *testing.T) {
defer dnsWaitGroup.Wait()
ctx, cancel := context.WithCancel(context.Background())
defer cancel()
_, err, ok := cgoLookupIP(ctx, "localhost")
_, err, ok := cgoLookupIP(ctx, "ip", "localhost")
if !ok {
t.Errorf("cgoLookupIP must not be a placeholder")
}

4
src/net/dial_test.go
View File

@ -346,7 +346,7 @@ func TestDialParallel(t *testing.T) {
}
}
func lookupSlowFast(ctx context.Context, fn func(context.Context, string) ([]IPAddr, error), host string) ([]IPAddr, error) {
func lookupSlowFast(ctx context.Context, fn func(context.Context, string, string) ([]IPAddr, error), network, host string) ([]IPAddr, error) {
switch host {
case "slow6loopback4":
// Returns a slow IPv6 address, and a local IPv4 address.
@ -355,7 +355,7 @@ func lookupSlowFast(ctx context.Context, fn func(context.Context, string) ([]IPA
{IP: ParseIP("127.0.0.1")},
}, nil
default:
return fn(ctx, host)
return fn(ctx, network, host)
}
}

6
src/net/error_test.go
View File

@ -144,7 +144,7 @@ func TestDialError(t *testing.T) {
origTestHookLookupIP := testHookLookupIP
defer func() { testHookLookupIP = origTestHookLookupIP }()
testHookLookupIP = func(ctx context.Context, fn func(context.Context, string) ([]IPAddr, error), host string) ([]IPAddr, error) {
testHookLookupIP = func(ctx context.Context, fn func(context.Context, string, string) ([]IPAddr, error), network, host string) ([]IPAddr, error) {
return nil, &DNSError{Err: "dial error test", Name: "name", Server: "server", IsTimeout: true}
}
sw.Set(socktest.FilterConnect, func(so *socktest.Status) (socktest.AfterFilter, error) {
@ -293,7 +293,7 @@ func TestListenError(t *testing.T) {
origTestHookLookupIP := testHookLookupIP
defer func() { testHookLookupIP = origTestHookLookupIP }()
testHookLookupIP = func(_ context.Context, fn func(context.Context, string) ([]IPAddr, error), host string) ([]IPAddr, error) {
testHookLookupIP = func(_ context.Context, fn func(context.Context, string, string) ([]IPAddr, error), network, host string) ([]IPAddr, error) {
return nil, &DNSError{Err: "listen error test", Name: "name", Server: "server", IsTimeout: true}
}
sw.Set(socktest.FilterListen, func(so *socktest.Status) (socktest.AfterFilter, error) {
@ -353,7 +353,7 @@ func TestListenPacketError(t *testing.T) {
origTestHookLookupIP := testHookLookupIP
defer func() { testHookLookupIP = origTestHookLookupIP }()
testHookLookupIP = func(_ context.Context, fn func(context.Context, string) ([]IPAddr, error), host string) ([]IPAddr, error) {
testHookLookupIP = func(_ context.Context, fn func(context.Context, string, string) ([]IPAddr, error), network, host string) ([]IPAddr, error) {
return nil, &DNSError{Err: "listen error test", Name: "name", Server: "server", IsTimeout: true}
}

5
src/net/hook.go
View File

@ -13,10 +13,11 @@ var (
testHookHostsPath = "/etc/hosts"
testHookLookupIP = func(
ctx context.Context,
fn func(context.Context, string) ([]IPAddr, error),
fn func(context.Context, string, string) ([]IPAddr, error),
network string,
host string,
) ([]IPAddr, error) {
return fn(ctx, host)
return fn(ctx, network, host)
}
testHookSetKeepAlive = func() {}
)

10
src/net/http/transport_test.go
View File

@ -3825,9 +3825,9 @@ func testTransportEventTrace(t *testing.T, h2 bool, noHooks bool) {
}
// Install a fake DNS server.
ctx := context.WithValue(context.Background(), nettrace.LookupIPAltResolverKey{}, func(ctx context.Context, host string) ([]net.IPAddr, error) {
ctx := context.WithValue(context.Background(), nettrace.LookupIPAltResolverKey{}, func(ctx context.Context, network, host string) ([]net.IPAddr, error) {
if host != "dns-is-faked.golang" {
t.Errorf("unexpected DNS host lookup for %q", host)
t.Errorf("unexpected DNS host lookup for %q/%q", network, host)
return nil, nil
}
return []net.IPAddr{{IP: net.ParseIP(ip)}}, nil
@ -4176,7 +4176,7 @@ func TestTransportMaxIdleConns(t *testing.T) {
if err != nil {
t.Fatal(err)
}
ctx := context.WithValue(context.Background(), nettrace.LookupIPAltResolverKey{}, func(ctx context.Context, host string) ([]net.IPAddr, error) {
ctx := context.WithValue(context.Background(), nettrace.LookupIPAltResolverKey{}, func(ctx context.Context, _, host string) ([]net.IPAddr, error) {
return []net.IPAddr{{IP: net.ParseIP(ip)}}, nil
})
@ -4416,9 +4416,9 @@ func testTransportIDNA(t *testing.T, h2 bool) {
}
// Install a fake DNS server.
ctx := context.WithValue(context.Background(), nettrace.LookupIPAltResolverKey{}, func(ctx context.Context, host string) ([]net.IPAddr, error) {
ctx := context.WithValue(context.Background(), nettrace.LookupIPAltResolverKey{}, func(ctx context.Context, network, host string) ([]net.IPAddr, error) {
if host != punyDomain {
t.Errorf("got DNS host lookup for %q; want %q", host, punyDomain)
t.Errorf("got DNS host lookup for %q/%q; want %q", network, host, punyDomain)
return nil, nil
}
return []net.IPAddr{{IP: net.ParseIP(ip)}}, nil

2
src/net/ipsock.go
View File

@ -277,7 +277,7 @@ func (r *Resolver) internetAddrList(ctx context.Context, net, addr string) (addr
}
// Try as a literal IP address, then as a DNS name.
ips, err := r.LookupIPAddr(ctx, host)
ips, err := r.lookupIPAddr(ctx, net, host)
if err != nil {
return nil, err
}

30
src/net/lookup.go
View File

@ -97,6 +97,19 @@ func lookupPortMap(network, service string) (port int, error error) {
return 0, &AddrError{Err: "unknown port", Addr: network + "/" + service}
}
// ipVersion returns the provided network's IP version: '4', '6' or 0
// if network does not end in a '4' or '6' byte.
func ipVersion(network string) byte {
if network == "" {
return 0
}
n := network[len(network)-1]
if n != '4' && n != '6' {
n = 0
}
return n
}
// DefaultResolver is the resolver used by the package-level Lookup
// functions and by Dialers without a specified Resolver.
var DefaultResolver = &Resolver{}
@ -189,6 +202,12 @@ func LookupIP(host string) ([]IP, error) {
// LookupIPAddr looks up host using the local resolver.
// It returns a slice of that host's IPv4 and IPv6 addresses.
func (r *Resolver) LookupIPAddr(ctx context.Context, host string) ([]IPAddr, error) {
return r.lookupIPAddr(ctx, "ip", host)
}
// lookupIPAddr looks up host using the local resolver and particular network.
// It returns a slice of that host's IPv4 and IPv6 addresses.
func (r *Resolver) lookupIPAddr(ctx context.Context, network, host string) ([]IPAddr, error) {
// Make sure that no matter what we do later, host=="" is rejected.
// parseIP, for example, does accept empty strings.
if host == "" {
@ -205,7 +224,7 @@ func (r *Resolver) LookupIPAddr(ctx context.Context, host string) ([]IPAddr, err
// can be overridden by tests. This is needed by net/http, so it
// uses a context key instead of unexported variables.
resolverFunc := r.lookupIP
if alt, _ := ctx.Value(nettrace.LookupIPAltResolverKey{}).(func(context.Context, string) ([]IPAddr, error)); alt != nil {
if alt, _ := ctx.Value(nettrace.LookupIPAltResolverKey{}).(func(context.Context, string, string) ([]IPAddr, error)); alt != nil {
resolverFunc = alt
}
@ -218,7 +237,7 @@ func (r *Resolver) LookupIPAddr(ctx context.Context, host string) ([]IPAddr, err
dnsWaitGroup.Add(1)
ch, called := r.getLookupGroup().DoChan(host, func() (interface{}, error) {
defer dnsWaitGroup.Done()
return testHookLookupIP(lookupGroupCtx, resolverFunc, host)
return testHookLookupIP(lookupGroupCtx, resolverFunc, network, host)
})
if !called {
dnsWaitGroup.Done()
@ -289,6 +308,13 @@ func LookupPort(network, service string) (port int, err error) {
func (r *Resolver) LookupPort(ctx context.Context, network, service string) (port int, err error) {
port, needsLookup := parsePort(service)
if needsLookup {
switch network {
case "tcp", "tcp4", "tcp6", "udp", "udp4", "udp6":
case "": // a hint wildcard for Go 1.0 undocumented behavior
network = "ip"
default:
return 0, &AddrError{Err: "unknown network", Addr: network}
}
port, err = r.lookupPort(ctx, network, service)
if err != nil {
return 0, err

2
src/net/lookup_fake.go
View File

@ -19,7 +19,7 @@ func (*Resolver) lookupHost(ctx context.Context, host string) (addrs []string, e
return nil, syscall.ENOPROTOOPT
}
func (*Resolver) lookupIP(ctx context.Context, host string) (addrs []IPAddr, err error) {
func (*Resolver) lookupIP(ctx context.Context, network, host string) (addrs []IPAddr, err error) {
return nil, syscall.ENOPROTOOPT
}

2
src/net/lookup_plan9.go
View File

@ -176,7 +176,7 @@ loop:
return
}
func (r *Resolver) lookupIP(ctx context.Context, host string) (addrs []IPAddr, err error) {
func (r *Resolver) lookupIP(ctx context.Context, _, host string) (addrs []IPAddr, err error) {
lits, err := r.lookupHost(ctx, host)
if err != nil {
return

30
src/net/lookup_test.go
View File

@ -20,7 +20,7 @@ import (
"time"
)
func lookupLocalhost(ctx context.Context, fn func(context.Context, string) ([]IPAddr, error), host string) ([]IPAddr, error) {
func lookupLocalhost(ctx context.Context, fn func(context.Context, string, string) ([]IPAddr, error), network, host string) ([]IPAddr, error) {
switch host {
case "localhost":
return []IPAddr{
@ -28,7 +28,7 @@ func lookupLocalhost(ctx context.Context, fn func(context.Context, string) ([]IP
{IP: IPv6loopback},
}, nil
default:
return fn(ctx, host)
return fn(ctx, network, host)
}
}
@ -1008,3 +1008,29 @@ func TestConcurrentPreferGoResolversDial(t *testing.T) {
}
}
}
var ipVersionTests = []struct {
network string
version byte
}{
{"tcp", 0},
{"tcp4", '4'},
{"tcp6", '6'},
{"udp", 0},
{"udp4", '4'},
{"udp6", '6'},
{"ip", 0},
{"ip4", '4'},
{"ip6", '6'},
{"ip7", 0},
{"", 0},
}
func TestIPVersion(t *testing.T) {
for _, tt := range ipVersionTests {
if version := ipVersion(tt.network); version != tt.version {
t.Errorf("Family for: %s. Expected: %s, Got: %s", tt.network,
string(tt.version), string(version))
}
}
}

4
src/net/lookup_unix.go
View File

@ -87,13 +87,13 @@ func (r *Resolver) lookupHost(ctx context.Context, host string) (addrs []string,
return r.goLookupHostOrder(ctx, host, order)
}
func (r *Resolver) lookupIP(ctx context.Context, host string) (addrs []IPAddr, err error) {
func (r *Resolver) lookupIP(ctx context.Context, network, host string) (addrs []IPAddr, err error) {
if r.preferGo() {
return r.goLookupIP(ctx, host)
}
order := systemConf().hostLookupOrder(r, host)
if order == hostLookupCgo {
if addrs, err, ok := cgoLookupIP(ctx, host); ok {
if addrs, err, ok := cgoLookupIP(ctx, network, host); ok {
return addrs, err
}
// cgo not available (or netgo); fall back to Go's DNS resolver

14
src/net/lookup_windows.go
View File

@ -65,7 +65,7 @@ func lookupProtocol(ctx context.Context, name string) (int, error) {
}
func (r *Resolver) lookupHost(ctx context.Context, name string) ([]string, error) {
ips, err := r.lookupIP(ctx, name)
ips, err := r.lookupIP(ctx, "ip", name)
if err != nil {
return nil, err
}
@ -76,14 +76,22 @@ func (r *Resolver) lookupHost(ctx context.Context, name string) ([]string, error
return addrs, nil
}
func (r *Resolver) lookupIP(ctx context.Context, name string) ([]IPAddr, error) {
func (r *Resolver) lookupIP(ctx context.Context, network, name string) ([]IPAddr, error) {
// TODO(bradfitz,brainman): use ctx more. See TODO below.
var family int32 = syscall.AF_UNSPEC
switch ipVersion(network) {
case '4':
family = syscall.AF_INET
case '6':
family = syscall.AF_INET6
}
getaddr := func() ([]IPAddr, error) {
acquireThread()
defer releaseThread()
hints := syscall.AddrinfoW{
Family: syscall.AF_UNSPEC,
Family: family,
Socktype: syscall.SOCK_STREAM,
Protocol: syscall.IPPROTO_IP,
}

2
src/net/netgo_unix_test.go
View File

@ -16,7 +16,7 @@ func TestGoLookupIP(t *testing.T) {
defer dnsWaitGroup.Wait()
host := "localhost"
ctx := context.Background()
_, err, ok := cgoLookupIP(ctx, host)
_, err, ok := cgoLookupIP(ctx, "ip", host)
if ok {
t.Errorf("cgoLookupIP must be a placeholder")
}