net: make resolveInternetAddr return a list of addresses
This CL makes resolveInternetAddr return a list of addresses that
contain a pair of different address family IP addresses if possible,
but doesn't contain any API behavioral changes yet. A simple IP
address selection mechanism for Resolve{TCP,UDP,IP}Addr and Dial API
still prefers IPv4.
This is in preparation for TCP connection setup with fast failover on
dual IP stack node as described in RFC 6555.
Update #3610
Update #5267
R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/13374043
diff --git a/src/pkg/net/dialgoogle_test.go b/src/pkg/net/dialgoogle_test.go
index f7939cc..000e1c3 100644
--- a/src/pkg/net/dialgoogle_test.go
+++ b/src/pkg/net/dialgoogle_test.go
@@ -16,6 +16,31 @@
// If an IPv6 tunnel is running, we can try dialing a real IPv6 address.
var testIPv6 = flag.Bool("ipv6", false, "assume ipv6 tunnel is present")
+func TestResolveGoogle(t *testing.T) {
+ if testing.Short() || !*testExternal {
+ t.Skip("skipping test to avoid external network")
+ }
+
+ for _, network := range []string{"tcp", "tcp4", "tcp6"} {
+ addr, err := ResolveTCPAddr(network, "www.google.com:http")
+ if err != nil {
+ if (network == "tcp" || network == "tcp4") && !supportsIPv4 {
+ t.Logf("ipv4 is not supported: %v", err)
+ } else if network == "tcp6" && !supportsIPv6 {
+ t.Logf("ipv6 is not supported: %v", err)
+ } else {
+ t.Errorf("ResolveTCPAddr failed: %v", err)
+ }
+ continue
+ }
+ if (network == "tcp" || network == "tcp4") && addr.IP.To4() == nil {
+ t.Errorf("got %v; expected an IPv4 address on %v", addr, network)
+ } else if network == "tcp6" && (addr.IP.To16() == nil || addr.IP.To4() != nil) {
+ t.Errorf("got %v; expected an IPv6 address on %v", addr, network)
+ }
+ }
+}
+
// fd is already connected to the destination, port 80.
// Run an HTTP request to fetch the appropriate page.
func fetchGoogle(t *testing.T, fd Conn, network, addr string) {
diff --git a/src/pkg/net/ipraw_test.go b/src/pkg/net/ipraw_test.go
index 5bee21a..becd732 100644
--- a/src/pkg/net/ipraw_test.go
+++ b/src/pkg/net/ipraw_test.go
@@ -16,10 +16,10 @@
)
type resolveIPAddrTest struct {
- net string
- litAddr string
- addr *IPAddr
- err error
+ net string
+ litAddrOrName string
+ addr *IPAddr
+ err error
}
var resolveIPAddrTests = []resolveIPAddrTest{
@@ -51,13 +51,20 @@
{"ip6", "fe80::1%" + index, &IPAddr{IP: ParseIP("fe80::1"), Zone: index}, nil},
}...)
}
+ if ips, err := LookupIP("localhost"); err == nil && len(ips) > 1 && supportsIPv4 && supportsIPv6 {
+ resolveIPAddrTests = append(resolveIPAddrTests, []resolveIPAddrTest{
+ {"ip", "localhost", &IPAddr{IP: IPv4(127, 0, 0, 1).To4()}, nil},
+ {"ip4", "localhost", &IPAddr{IP: IPv4(127, 0, 0, 1).To4()}, nil},
+ {"ip6", "localhost", &IPAddr{IP: IPv6loopback}, nil},
+ }...)
+ }
}
func TestResolveIPAddr(t *testing.T) {
for _, tt := range resolveIPAddrTests {
- addr, err := ResolveIPAddr(tt.net, tt.litAddr)
+ addr, err := ResolveIPAddr(tt.net, tt.litAddrOrName)
if err != tt.err {
- t.Fatalf("ResolveIPAddr(%v, %v) failed: %v", tt.net, tt.litAddr, err)
+ t.Fatalf("ResolveIPAddr(%v, %v) failed: %v", tt.net, tt.litAddrOrName, err)
} else if !reflect.DeepEqual(addr, tt.addr) {
t.Fatalf("got %#v; expected %#v", addr, tt.addr)
}
diff --git a/src/pkg/net/ipsock.go b/src/pkg/net/ipsock.go
index 2040787..a4601ba 100644
--- a/src/pkg/net/ipsock.go
+++ b/src/pkg/net/ipsock.go
@@ -60,44 +60,61 @@
var errNoSuitableAddress = errors.New("no suitable address found")
-// firstFavoriteAddr returns an address that implemets netaddr
-// interface.
-func firstFavoriteAddr(filter func(IP) IP, addrs []string, inetaddr func(IP) netaddr) (netaddr, error) {
- if filter == nil {
- // We'll take any IP address, but since the dialing code
- // does not yet try multiple addresses, prefer to use
- // an IPv4 address if possible. This is especially relevant
- // if localhost resolves to [ipv6-localhost, ipv4-localhost].
- // Too much code assumes localhost == ipv4-localhost.
- addr, err := firstSupportedAddr(ipv4only, addrs, inetaddr)
- if err != nil {
- addr, err = firstSupportedAddr(anyaddr, addrs, inetaddr)
+// firstFavoriteAddr returns an address or a list of addresses that
+// implement the netaddr interface. Known filters are nil, ipv4only
+// and ipv6only. It returns any address when filter is nil. The result
+// contains at least one address when error is nil.
+func firstFavoriteAddr(filter func(IP) IP, ips []IP, inetaddr func(IP) netaddr) (netaddr, error) {
+ if filter != nil {
+ return firstSupportedAddr(filter, ips, inetaddr)
+ }
+ var (
+ ipv4, ipv6, swap bool
+ list addrList
+ )
+ for _, ip := range ips {
+ // We'll take any IP address, but since the dialing
+ // code does not yet try multiple addresses
+ // effectively, prefer to use an IPv4 address if
+ // possible. This is especially relevant if localhost
+ // resolves to [ipv6-localhost, ipv4-localhost]. Too
+ // much code assumes localhost == ipv4-localhost.
+ if ip4 := ipv4only(ip); ip4 != nil && !ipv4 {
+ list = append(list, inetaddr(ip4))
+ ipv4 = true
+ if ipv6 {
+ swap = true
+ }
+ } else if ip6 := ipv6only(ip); ip6 != nil && !ipv6 {
+ list = append(list, inetaddr(ip6))
+ ipv6 = true
}
- return addr, err
- } else {
- return firstSupportedAddr(filter, addrs, inetaddr)
+ if ipv4 && ipv6 {
+ if swap {
+ list[0], list[1] = list[1], list[0]
+ }
+ break
+ }
+ }
+ switch len(list) {
+ case 0:
+ return nil, errNoSuitableAddress
+ case 1:
+ return list[0], nil
+ default:
+ return list, nil
}
}
-func firstSupportedAddr(filter func(IP) IP, addrs []string, inetaddr func(IP) netaddr) (netaddr, error) {
- for _, s := range addrs {
- if ip := filter(ParseIP(s)); ip != nil {
+func firstSupportedAddr(filter func(IP) IP, ips []IP, inetaddr func(IP) netaddr) (netaddr, error) {
+ for _, ip := range ips {
+ if ip := filter(ip); ip != nil {
return inetaddr(ip), nil
}
}
return nil, errNoSuitableAddress
}
-// anyaddr returns IP addresses that we can use with the current
-// kernel configuration. It returns nil when ip is not suitable for
-// the configuration and an IP address.
-func anyaddr(ip IP) IP {
- if ip4 := ipv4only(ip); ip4 != nil {
- return ip4
- }
- return ipv6only(ip)
-}
-
// ipv4only returns IPv4 addresses that we can use with the kernel's
// IPv4 addressing modes. It returns IPv4-mapped IPv6 addresses as
// IPv4 addresses and returns other IPv6 address types as nils.
@@ -212,8 +229,11 @@
}
// resolveInternetAddr resolves addr that is either a literal IP
-// address or a DNS registered name and returns an internet protocol
-// family address.
+// address or a DNS name and returns an internet protocol family
+// address. It returns a list that contains a pair of different
+// address family addresses when addr is a DNS name and the name has
+// mutiple address family records. The result contains at least one
+// address when error is nil.
func resolveInternetAddr(net, addr string, deadline time.Time) (netaddr, error) {
var (
err error
@@ -260,9 +280,9 @@
if ip, zone = parseIPv6(host, true); ip != nil {
return inetaddr(ip), nil
}
- // Try as a DNS registered name.
+ // Try as a DNS name.
host, zone = splitHostZone(host)
- addrs, err := lookupHostDeadline(host, deadline)
+ ips, err := lookupIPDeadline(host, deadline)
if err != nil {
return nil, err
}
@@ -273,7 +293,7 @@
if net != "" && net[len(net)-1] == '6' || zone != "" {
filter = ipv6only
}
- return firstFavoriteAddr(filter, addrs, inetaddr)
+ return firstFavoriteAddr(filter, ips, inetaddr)
}
func zoneToString(zone int) string {
diff --git a/src/pkg/net/ipsock_test.go b/src/pkg/net/ipsock_test.go
new file mode 100644
index 0000000..522266f
--- /dev/null
+++ b/src/pkg/net/ipsock_test.go
@@ -0,0 +1,189 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package net
+
+import (
+ "reflect"
+ "testing"
+)
+
+var testInetaddr = func(ip IP) netaddr { return &TCPAddr{IP: ip, Port: 5682} }
+
+var firstFavoriteAddrTests = []struct {
+ filter func(IP) IP
+ ips []IP
+ inetaddr func(IP) netaddr
+ addr netaddr
+ err error
+}{
+ {
+ nil,
+ []IP{
+ IPv4(127, 0, 0, 1),
+ IPv6loopback,
+ },
+ testInetaddr,
+ addrList{
+ &TCPAddr{IP: IPv4(127, 0, 0, 1).To4(), Port: 5682},
+ &TCPAddr{IP: IPv6loopback, Port: 5682},
+ },
+ nil,
+ },
+ {
+ nil,
+ []IP{
+ IPv6loopback,
+ IPv4(127, 0, 0, 1),
+ },
+ testInetaddr,
+ addrList{
+ &TCPAddr{IP: IPv4(127, 0, 0, 1).To4(), Port: 5682},
+ &TCPAddr{IP: IPv6loopback, Port: 5682},
+ },
+ nil,
+ },
+ {
+ nil,
+ []IP{
+ IPv4(127, 0, 0, 1),
+ IPv4(192, 168, 0, 1),
+ },
+ testInetaddr,
+ &TCPAddr{IP: IPv4(127, 0, 0, 1).To4(), Port: 5682},
+ nil,
+ },
+ {
+ nil,
+ []IP{
+ IPv6loopback,
+ ParseIP("fe80::1"),
+ },
+ testInetaddr,
+ &TCPAddr{IP: IPv6loopback, Port: 5682},
+ nil,
+ },
+ {
+ nil,
+ []IP{
+ IPv4(127, 0, 0, 1),
+ IPv4(192, 168, 0, 1),
+ IPv6loopback,
+ ParseIP("fe80::1"),
+ },
+ testInetaddr,
+ addrList{
+ &TCPAddr{IP: IPv4(127, 0, 0, 1).To4(), Port: 5682},
+ &TCPAddr{IP: IPv6loopback, Port: 5682},
+ },
+ nil,
+ },
+ {
+ nil,
+ []IP{
+ IPv6loopback,
+ ParseIP("fe80::1"),
+ IPv4(127, 0, 0, 1),
+ IPv4(192, 168, 0, 1),
+ },
+ testInetaddr,
+ addrList{
+ &TCPAddr{IP: IPv4(127, 0, 0, 1).To4(), Port: 5682},
+ &TCPAddr{IP: IPv6loopback, Port: 5682},
+ },
+ nil,
+ },
+ {
+ nil,
+ []IP{
+ IPv4(127, 0, 0, 1),
+ IPv6loopback,
+ IPv4(192, 168, 0, 1),
+ ParseIP("fe80::1"),
+ },
+ testInetaddr,
+ addrList{
+ &TCPAddr{IP: IPv4(127, 0, 0, 1).To4(), Port: 5682},
+ &TCPAddr{IP: IPv6loopback, Port: 5682},
+ },
+ nil,
+ },
+ {
+ nil,
+ []IP{
+ IPv6loopback,
+ IPv4(127, 0, 0, 1),
+ ParseIP("fe80::1"),
+ IPv4(192, 168, 0, 1),
+ },
+ testInetaddr,
+ addrList{
+ &TCPAddr{IP: IPv4(127, 0, 0, 1).To4(), Port: 5682},
+ &TCPAddr{IP: IPv6loopback, Port: 5682},
+ },
+ nil,
+ },
+
+ {
+ ipv4only,
+ []IP{
+ IPv4(127, 0, 0, 1),
+ IPv6loopback,
+ },
+ testInetaddr,
+ &TCPAddr{IP: IPv4(127, 0, 0, 1).To4(), Port: 5682},
+ nil,
+ },
+ {
+ ipv4only,
+ []IP{
+ IPv6loopback,
+ IPv4(127, 0, 0, 1),
+ },
+ testInetaddr,
+ &TCPAddr{IP: IPv4(127, 0, 0, 1).To4(), Port: 5682},
+ nil,
+ },
+
+ {
+ ipv6only,
+ []IP{
+ IPv4(127, 0, 0, 1),
+ IPv6loopback,
+ },
+ testInetaddr,
+ &TCPAddr{IP: IPv6loopback, Port: 5682},
+ nil,
+ },
+ {
+ ipv6only,
+ []IP{
+ IPv6loopback,
+ IPv4(127, 0, 0, 1),
+ },
+ testInetaddr,
+ &TCPAddr{IP: IPv6loopback, Port: 5682},
+ nil,
+ },
+
+ {nil, nil, testInetaddr, nil, errNoSuitableAddress},
+
+ {ipv4only, nil, testInetaddr, nil, errNoSuitableAddress},
+ {ipv4only, []IP{IPv6loopback}, testInetaddr, nil, errNoSuitableAddress},
+
+ {ipv6only, nil, testInetaddr, nil, errNoSuitableAddress},
+ {ipv6only, []IP{IPv4(127, 0, 0, 1)}, testInetaddr, nil, errNoSuitableAddress},
+}
+
+func TestFirstFavoriteAddr(t *testing.T) {
+ for i, tt := range firstFavoriteAddrTests {
+ addr, err := firstFavoriteAddr(tt.filter, tt.ips, tt.inetaddr)
+ if err != tt.err {
+ t.Errorf("#%v: got %v; expected %v", i, err, tt.err)
+ }
+ if !reflect.DeepEqual(addr, tt.addr) {
+ t.Errorf("#%v: got %v; expected %v", i, addr, tt.addr)
+ }
+ }
+}
diff --git a/src/pkg/net/lookup.go b/src/pkg/net/lookup.go
index 0cd1993..0a10de2 100644
--- a/src/pkg/net/lookup.go
+++ b/src/pkg/net/lookup.go
@@ -23,19 +23,19 @@
var lookupGroup singleflight
-// lookupHostMerge wraps lookupHost, but makes sure that for any given
+// lookupIPMerge wraps lookupIP, but makes sure that for any given
// host, only one lookup is in-flight at a time. The returned memory
// is always owned by the caller.
-func lookupHostMerge(host string) (addrs []string, err error) {
+func lookupIPMerge(host string) (addrs []IP, err error) {
addrsi, err, shared := lookupGroup.Do(host, func() (interface{}, error) {
- return lookupHost(host)
+ return lookupIP(host)
})
if err != nil {
return nil, err
}
- addrs = addrsi.([]string)
+ addrs = addrsi.([]IP)
if shared {
- clone := make([]string, len(addrs))
+ clone := make([]IP, len(addrs))
copy(clone, addrs)
addrs = clone
}
@@ -45,12 +45,12 @@
// LookupHost looks up the given host using the local resolver.
// It returns an array of that host's addresses.
func LookupHost(host string) (addrs []string, err error) {
- return lookupHostMerge(host)
+ return lookupHost(host)
}
-func lookupHostDeadline(host string, deadline time.Time) (addrs []string, err error) {
+func lookupIPDeadline(host string, deadline time.Time) (addrs []IP, err error) {
if deadline.IsZero() {
- return lookupHostMerge(host)
+ return lookupIPMerge(host)
}
// TODO(bradfitz): consider pushing the deadline down into the
@@ -68,12 +68,12 @@
t := time.NewTimer(timeout)
defer t.Stop()
type res struct {
- addrs []string
+ addrs []IP
err error
}
resc := make(chan res, 1)
go func() {
- a, err := lookupHostMerge(host)
+ a, err := lookupIPMerge(host)
resc <- res{a, err}
}()
select {
@@ -88,7 +88,7 @@
// LookupIP looks up host using the local resolver.
// It returns an array of that host's IPv4 and IPv6 addresses.
func LookupIP(host string) (addrs []IP, err error) {
- return lookupIP(host)
+ return lookupIPMerge(host)
}
// LookupPort looks up the port for the given network and service.
diff --git a/src/pkg/net/tcp_test.go b/src/pkg/net/tcp_test.go
index 1af9616..a9c7562 100644
--- a/src/pkg/net/tcp_test.go
+++ b/src/pkg/net/tcp_test.go
@@ -273,10 +273,10 @@
}
type resolveTCPAddrTest struct {
- net string
- litAddr string
- addr *TCPAddr
- err error
+ net string
+ litAddrOrName string
+ addr *TCPAddr
+ err error
}
var resolveTCPAddrTests = []resolveTCPAddrTest{
@@ -303,13 +303,20 @@
{"tcp6", "[fe80::1%" + index + "]:4", &TCPAddr{IP: ParseIP("fe80::1"), Port: 4, Zone: index}, nil},
}...)
}
+ if ips, err := LookupIP("localhost"); err == nil && len(ips) > 1 && supportsIPv4 && supportsIPv6 {
+ resolveTCPAddrTests = append(resolveTCPAddrTests, []resolveTCPAddrTest{
+ {"tcp", "localhost:5", &TCPAddr{IP: IPv4(127, 0, 0, 1).To4(), Port: 5}, nil},
+ {"tcp4", "localhost:6", &TCPAddr{IP: IPv4(127, 0, 0, 1).To4(), Port: 6}, nil},
+ {"tcp6", "localhost:7", &TCPAddr{IP: IPv6loopback, Port: 7}, nil},
+ }...)
+ }
}
func TestResolveTCPAddr(t *testing.T) {
for _, tt := range resolveTCPAddrTests {
- addr, err := ResolveTCPAddr(tt.net, tt.litAddr)
+ addr, err := ResolveTCPAddr(tt.net, tt.litAddrOrName)
if err != tt.err {
- t.Fatalf("ResolveTCPAddr(%v, %v) failed: %v", tt.net, tt.litAddr, err)
+ t.Fatalf("ResolveTCPAddr(%q, %q) failed: %v", tt.net, tt.litAddrOrName, err)
}
if !reflect.DeepEqual(addr, tt.addr) {
t.Fatalf("got %#v; expected %#v", addr, tt.addr)
diff --git a/src/pkg/net/udp_test.go b/src/pkg/net/udp_test.go
index f6a61ce..fc73a79 100644
--- a/src/pkg/net/udp_test.go
+++ b/src/pkg/net/udp_test.go
@@ -12,10 +12,10 @@
)
type resolveUDPAddrTest struct {
- net string
- litAddr string
- addr *UDPAddr
- err error
+ net string
+ litAddrOrName string
+ addr *UDPAddr
+ err error
}
var resolveUDPAddrTests = []resolveUDPAddrTest{
@@ -42,13 +42,20 @@
{"udp6", "[fe80::1%" + index + "]:4", &UDPAddr{IP: ParseIP("fe80::1"), Port: 4, Zone: index}, nil},
}...)
}
+ if ips, err := LookupIP("localhost"); err == nil && len(ips) > 1 && supportsIPv4 && supportsIPv6 {
+ resolveUDPAddrTests = append(resolveUDPAddrTests, []resolveUDPAddrTest{
+ {"udp", "localhost:5", &UDPAddr{IP: IPv4(127, 0, 0, 1).To4(), Port: 5}, nil},
+ {"udp4", "localhost:6", &UDPAddr{IP: IPv4(127, 0, 0, 1).To4(), Port: 6}, nil},
+ {"udp6", "localhost:7", &UDPAddr{IP: IPv6loopback, Port: 7}, nil},
+ }...)
+ }
}
func TestResolveUDPAddr(t *testing.T) {
for _, tt := range resolveUDPAddrTests {
- addr, err := ResolveUDPAddr(tt.net, tt.litAddr)
+ addr, err := ResolveUDPAddr(tt.net, tt.litAddrOrName)
if err != tt.err {
- t.Fatalf("ResolveUDPAddr(%v, %v) failed: %v", tt.net, tt.litAddr, err)
+ t.Fatalf("ResolveUDPAddr(%q, %q) failed: %v", tt.net, tt.litAddrOrName, err)
}
if !reflect.DeepEqual(addr, tt.addr) {
t.Fatalf("got %#v; expected %#v", addr, tt.addr)
