net: expand nss myhostname fallback detection

Expand myhostname fallback detection to properly detect the local
hostname in addition to other supported special names and suffixes.

Fixes #17967

Change-Id: I1fe141fd9838b25886c08b6f2fd325e58be60457
Reviewed-on: https://go-review.googlesource.com/33550
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

diff --git a/src/net/conf.go b/src/net/conf.go
index 41e62d5689008c8fadfa0755266e60dbb13b594a..c10aafe63aba51800384e8a53a58ad486c27d4b4 100644 (file)
--- a/src/net/conf.go
+++ b/src/net/conf.go
@@ -179,8 +179,6 @@ func (c *conf) hostLookupOrder(hostname string) (ret hostLookupOrder) {
                }
        }
 
-       hasDot := byteIndex(hostname, '.') != -1
-
        // Canonicalize the hostname by removing any trailing dot.
        if stringsHasSuffix(hostname, ".") {
                hostname = hostname[:len(hostname)-1]
@@ -220,10 +218,14 @@ func (c *conf) hostLookupOrder(hostname string) (ret hostLookupOrder) {
        var first string
        for _, src := range srcs {
                if src.source == "myhostname" {
-                       if hostname == "" || hasDot {
-                               continue
+                       if isLocalhost(hostname) || isGateway(hostname) {
+                               return fallbackOrder
                        }
-                       return fallbackOrder
+                       hn, err := getHostname()
+                       if err != nil || stringsEqualFold(hostname, hn) {
+                               return fallbackOrder
+                       }
+                       continue
                }
                if src.source == "files" || src.source == "dns" {
                        if !src.standardCriteria() {
@@ -306,3 +308,15 @@ func goDebugNetDNS() (dnsMode string, debugLevel int) {
        parsePart(goDebug)
        return
 }
+
+// isLocalhost reports whether h should be considered a "localhost"
+// name for the myhostname NSS module.
+func isLocalhost(h string) bool {
+       return stringsEqualFold(h, "localhost") || stringsEqualFold(h, "localhost.localdomain") || stringsHasSuffixFold(h, ".localhost") || stringsHasSuffixFold(h, ".localhost.localdomain")
+}
+
+// isGateway reports whether h should be considered a "gateway"
+// name for the myhostname NSS module.
+func isGateway(h string) bool {
+       return stringsEqualFold(h, "gateway")
+}

diff --git a/src/net/conf_test.go b/src/net/conf_test.go
index ec8814b845b738edce7dffcf54be32b06f673293..17d03f4b5fc55f739a5e6017ea2eb941f5dacfb7 100644 (file)
--- a/src/net/conf_test.go
+++ b/src/net/conf_test.go
@@ -13,8 +13,9 @@ import (
 )
 
 type nssHostTest struct {
-       host string
-       want hostLookupOrder
+       host      string
+       localhost string
+       want      hostLookupOrder
 }
 
 func nssStr(s string) *nssConf { return parseNSSConf(strings.NewReader(s)) }
@@ -42,8 +43,8 @@ func TestConfHostLookupOrder(t *testing.T) {
                                resolv:             defaultResolvConf,
                        },
                        hostTests: []nssHostTest{
-                               {"foo.local", hostLookupCgo},
-                               {"google.com", hostLookupCgo},
+                               {"foo.local", "myhostname", hostLookupCgo},
+                               {"google.com", "myhostname", hostLookupCgo},
                        },
                },
                {
@@ -54,7 +55,7 @@ func TestConfHostLookupOrder(t *testing.T) {
                                resolv: defaultResolvConf,
                        },
                        hostTests: []nssHostTest{
-                               {"x.com", hostLookupDNSFiles},
+                               {"x.com", "myhostname", hostLookupDNSFiles},
                        },
                },
                {
@@ -65,7 +66,7 @@ func TestConfHostLookupOrder(t *testing.T) {
                                resolv: defaultResolvConf,
                        },
                        hostTests: []nssHostTest{
-                               {"x.com", hostLookupFilesDNS},
+                               {"x.com", "myhostname", hostLookupFilesDNS},
                        },
                },
                {
@@ -75,11 +76,11 @@ func TestConfHostLookupOrder(t *testing.T) {
                                resolv: defaultResolvConf,
                        },
                        hostTests: []nssHostTest{
-                               {"foo.local", hostLookupCgo},
-                               {"foo.local.", hostLookupCgo},
-                               {"foo.LOCAL", hostLookupCgo},
-                               {"foo.LOCAL.", hostLookupCgo},
-                               {"google.com", hostLookupFilesDNS},
+                               {"foo.local", "myhostname", hostLookupCgo},
+                               {"foo.local.", "myhostname", hostLookupCgo},
+                               {"foo.LOCAL", "myhostname", hostLookupCgo},
+                               {"foo.LOCAL.", "myhostname", hostLookupCgo},
+                               {"google.com", "myhostname", hostLookupFilesDNS},
                        },
                },
                {
@@ -89,7 +90,7 @@ func TestConfHostLookupOrder(t *testing.T) {
                                nss:    nssStr("foo: bar"),
                                resolv: defaultResolvConf,
                        },
-                       hostTests: []nssHostTest{{"google.com", hostLookupFilesDNS}},
+                       hostTests: []nssHostTest{{"google.com", "myhostname", hostLookupFilesDNS}},
                },
                // On OpenBSD, no resolv.conf means no DNS.
                {
@@ -98,7 +99,7 @@ func TestConfHostLookupOrder(t *testing.T) {
                                goos:   "openbsd",
                                resolv: defaultResolvConf,
                        },
-                       hostTests: []nssHostTest{{"google.com", hostLookupFiles}},
+                       hostTests: []nssHostTest{{"google.com", "myhostname", hostLookupFiles}},
                },
                {
                        name: "solaris_no_nsswitch",
@@ -107,7 +108,7 @@ func TestConfHostLookupOrder(t *testing.T) {
                                nss:    &nssConf{err: os.ErrNotExist},
                                resolv: defaultResolvConf,
                        },
-                       hostTests: []nssHostTest{{"google.com", hostLookupCgo}},
+                       hostTests: []nssHostTest{{"google.com", "myhostname", hostLookupCgo}},
                },
                {
                        name: "openbsd_lookup_bind_file",
@@ -116,8 +117,8 @@ func TestConfHostLookupOrder(t *testing.T) {
                                resolv: &dnsConfig{lookup: []string{"bind", "file"}},
                        },
                        hostTests: []nssHostTest{
-                               {"google.com", hostLookupDNSFiles},
-                               {"foo.local", hostLookupDNSFiles},
+                               {"google.com", "myhostname", hostLookupDNSFiles},
+                               {"foo.local", "myhostname", hostLookupDNSFiles},
                        },
                },
                {
@@ -126,7 +127,7 @@ func TestConfHostLookupOrder(t *testing.T) {
                                goos:   "openbsd",
                                resolv: &dnsConfig{lookup: []string{"file", "bind"}},
                        },
-                       hostTests: []nssHostTest{{"google.com", hostLookupFilesDNS}},
+                       hostTests: []nssHostTest{{"google.com", "myhostname", hostLookupFilesDNS}},
                },
                {
                        name: "openbsd_lookup_bind",
@@ -134,7 +135,7 @@ func TestConfHostLookupOrder(t *testing.T) {
                                goos:   "openbsd",
                                resolv: &dnsConfig{lookup: []string{"bind"}},
                        },
-                       hostTests: []nssHostTest{{"google.com", hostLookupDNS}},
+                       hostTests: []nssHostTest{{"google.com", "myhostname", hostLookupDNS}},
                },
                {
                        name: "openbsd_lookup_file",
@@ -142,7 +143,7 @@ func TestConfHostLookupOrder(t *testing.T) {
                                goos:   "openbsd",
                                resolv: &dnsConfig{lookup: []string{"file"}},
                        },
-                       hostTests: []nssHostTest{{"google.com", hostLookupFiles}},
+                       hostTests: []nssHostTest{{"google.com", "myhostname", hostLookupFiles}},
                },
                {
                        name: "openbsd_lookup_yp",
@@ -150,7 +151,7 @@ func TestConfHostLookupOrder(t *testing.T) {
                                goos:   "openbsd",
                                resolv: &dnsConfig{lookup: []string{"file", "bind", "yp"}},
                        },
-                       hostTests: []nssHostTest{{"google.com", hostLookupCgo}},
+                       hostTests: []nssHostTest{{"google.com", "myhostname", hostLookupCgo}},
                },
                {
                        name: "openbsd_lookup_two",
@@ -158,7 +159,7 @@ func TestConfHostLookupOrder(t *testing.T) {
                                goos:   "openbsd",
                                resolv: &dnsConfig{lookup: []string{"file", "foo"}},
                        },
-                       hostTests: []nssHostTest{{"google.com", hostLookupCgo}},
+                       hostTests: []nssHostTest{{"google.com", "myhostname", hostLookupCgo}},
                },
                {
                        name: "openbsd_lookup_empty",
@@ -166,7 +167,7 @@ func TestConfHostLookupOrder(t *testing.T) {
                                goos:   "openbsd",
                                resolv: &dnsConfig{lookup: nil},
                        },
-                       hostTests: []nssHostTest{{"google.com", hostLookupDNSFiles}},
+                       hostTests: []nssHostTest{{"google.com", "myhostname", hostLookupDNSFiles}},
                },
                // glibc lacking an nsswitch.conf, per
                // http://www.gnu.org/software/libc/manual/html_node/Notes-on-NSS-Configuration-File.html
@@ -177,7 +178,7 @@ func TestConfHostLookupOrder(t *testing.T) {
                                nss:    &nssConf{err: os.ErrNotExist},
                                resolv: defaultResolvConf,
                        },
-                       hostTests: []nssHostTest{{"google.com", hostLookupDNSFiles}},
+                       hostTests: []nssHostTest{{"google.com", "myhostname", hostLookupDNSFiles}},
                },
                {
                        name: "files_mdns_dns",
@@ -186,8 +187,8 @@ func TestConfHostLookupOrder(t *testing.T) {
                                resolv: defaultResolvConf,
                        },
                        hostTests: []nssHostTest{
-                               {"x.com", hostLookupFilesDNS},
-                               {"x.local", hostLookupCgo},
+                               {"x.com", "myhostname", hostLookupFilesDNS},
+                               {"x.local", "myhostname", hostLookupCgo},
                        },
                },
                {
@@ -197,9 +198,9 @@ func TestConfHostLookupOrder(t *testing.T) {
                                resolv: defaultResolvConf,
                        },
                        hostTests: []nssHostTest{
-                               {"x.com", hostLookupDNS},
-                               {"x\\.com", hostLookupCgo},     // punt on weird glibc escape
-                               {"foo.com%en0", hostLookupCgo}, // and IPv6 zones
+                               {"x.com", "myhostname", hostLookupDNS},
+                               {"x\\.com", "myhostname", hostLookupCgo},     // punt on weird glibc escape
+                               {"foo.com%en0", "myhostname", hostLookupCgo}, // and IPv6 zones
                        },
                },
                {
@@ -210,8 +211,8 @@ func TestConfHostLookupOrder(t *testing.T) {
                                hasMDNSAllow: true,
                        },
                        hostTests: []nssHostTest{
-                               {"x.com", hostLookupCgo},
-                               {"x.local", hostLookupCgo},
+                               {"x.com", "myhostname", hostLookupCgo},
+                               {"x.local", "myhostname", hostLookupCgo},
                        },
                },
                {
@@ -221,9 +222,9 @@ func TestConfHostLookupOrder(t *testing.T) {
                                resolv: defaultResolvConf,
                        },
                        hostTests: []nssHostTest{
-                               {"x.com", hostLookupFilesDNS},
-                               {"x", hostLookupFilesDNS},
-                               {"x.local", hostLookupCgo},
+                               {"x.com", "myhostname", hostLookupFilesDNS},
+                               {"x", "myhostname", hostLookupFilesDNS},
+                               {"x.local", "myhostname", hostLookupCgo},
                        },
                },
                {
@@ -233,9 +234,9 @@ func TestConfHostLookupOrder(t *testing.T) {
                                resolv: defaultResolvConf,
                        },
                        hostTests: []nssHostTest{
-                               {"x.com", hostLookupDNSFiles},
-                               {"x", hostLookupDNSFiles},
-                               {"x.local", hostLookupCgo},
+                               {"x.com", "myhostname", hostLookupDNSFiles},
+                               {"x", "myhostname", hostLookupDNSFiles},
+                               {"x.local", "myhostname", hostLookupCgo},
                        },
                },
                {
@@ -245,7 +246,7 @@ func TestConfHostLookupOrder(t *testing.T) {
                                resolv: defaultResolvConf,
                        },
                        hostTests: []nssHostTest{
-                               {"x.com", hostLookupCgo},
+                               {"x.com", "myhostname", hostLookupCgo},
                        },
                },
                {
@@ -255,9 +256,23 @@ func TestConfHostLookupOrder(t *testing.T) {
                                resolv: defaultResolvConf,
                        },
                        hostTests: []nssHostTest{
-                               {"x.com", hostLookupFilesDNS},
-                               {"somehostname", hostLookupCgo},
-                               {"", hostLookupFilesDNS}, // Issue 13623
+                               {"x.com", "myhostname", hostLookupFilesDNS},
+                               {"myhostname", "myhostname", hostLookupCgo},
+                               {"myHostname", "myhostname", hostLookupCgo},
+                               {"myhostname.dot", "myhostname.dot", hostLookupCgo},
+                               {"myHostname.dot", "myhostname.dot", hostLookupCgo},
+                               {"gateway", "myhostname", hostLookupCgo},
+                               {"Gateway", "myhostname", hostLookupCgo},
+                               {"localhost", "myhostname", hostLookupCgo},
+                               {"Localhost", "myhostname", hostLookupCgo},
+                               {"anything.localhost", "myhostname", hostLookupCgo},
+                               {"Anything.localhost", "myhostname", hostLookupCgo},
+                               {"localhost.localdomain", "myhostname", hostLookupCgo},
+                               {"Localhost.Localdomain", "myhostname", hostLookupCgo},
+                               {"anything.localhost.localdomain", "myhostname", hostLookupCgo},
+                               {"Anything.Localhost.Localdomain", "myhostname", hostLookupCgo},
+                               {"somehostname", "myhostname", hostLookupFilesDNS},
+                               {"", "myhostname", hostLookupFilesDNS}, // Issue 13623
                        },
                },
                {
@@ -267,8 +282,9 @@ func TestConfHostLookupOrder(t *testing.T) {
                                resolv: defaultResolvConf,
                        },
                        hostTests: []nssHostTest{
-                               {"x.com", hostLookupFilesDNS},
-                               {"somehostname", hostLookupCgo},
+                               {"x.com", "myhostname", hostLookupFilesDNS},
+                               {"somehostname", "myhostname", hostLookupFilesDNS},
+                               {"myhostname", "myhostname", hostLookupCgo},
                        },
                },
                // Debian Squeeze is just "dns,files", but lists all
@@ -282,8 +298,8 @@ func TestConfHostLookupOrder(t *testing.T) {
                                resolv: defaultResolvConf,
                        },
                        hostTests: []nssHostTest{
-                               {"x.com", hostLookupDNSFiles},
-                               {"somehostname", hostLookupDNSFiles},
+                               {"x.com", "myhostname", hostLookupDNSFiles},
+                               {"somehostname", "myhostname", hostLookupDNSFiles},
                        },
                },
                {
@@ -292,7 +308,7 @@ func TestConfHostLookupOrder(t *testing.T) {
                                nss:    nssStr("foo: bar"),
                                resolv: &dnsConfig{servers: defaultNS, ndots: 1, timeout: 5, attempts: 2, unknownOpt: true},
                        },
-                       hostTests: []nssHostTest{{"google.com", hostLookupCgo}},
+                       hostTests: []nssHostTest{{"google.com", "myhostname", hostLookupCgo}},
                },
                // Android should always use cgo.
                {
@@ -303,12 +319,18 @@ func TestConfHostLookupOrder(t *testing.T) {
                                resolv: defaultResolvConf,
                        },
                        hostTests: []nssHostTest{
-                               {"x.com", hostLookupCgo},
+                               {"x.com", "myhostname", hostLookupCgo},
                        },
                },
        }
+
+       origGetHostname := getHostname
+       defer func() { getHostname = origGetHostname }()
+
        for _, tt := range tests {
                for _, ht := range tt.hostTests {
+                       getHostname = func() (string, error) { return ht.localhost, nil }
+
                        gotOrder := tt.c.hostLookupOrder(ht.host)
                        if gotOrder != ht.want {
                                t.Errorf("%s: hostLookupOrder(%q) = %v; want %v", tt.name, ht.host, gotOrder, ht.want)

diff --git a/src/net/parse.go b/src/net/parse.go
index d615eb2b567418e567411996528b2824dbda757d..58269849ce9fcf3ddca529de88d285e5ff68f0c1 100644 (file)
--- a/src/net/parse.go
+++ b/src/net/parse.go
@@ -334,22 +334,28 @@ func stringsHasSuffix(s, suffix string) bool {
 // stringsHasSuffixFold reports whether s ends in suffix,
 // ASCII-case-insensitively.
 func stringsHasSuffixFold(s, suffix string) bool {
-       if len(suffix) > len(s) {
+       return len(s) >= len(suffix) && stringsEqualFold(s[len(s)-len(suffix):], suffix)
+}
+
+// stringsHasPrefix is strings.HasPrefix. It reports whether s begins with prefix.
+func stringsHasPrefix(s, prefix string) bool {
+       return len(s) >= len(prefix) && s[:len(prefix)] == prefix
+}
+
+// stringsEqualFold is strings.EqualFold, ASCII only. It reports whether s and t
+// are equal, ASCII-case-insensitively.
+func stringsEqualFold(s, t string) bool {
+       if len(s) != len(t) {
                return false
        }
-       for i := 0; i < len(suffix); i++ {
-               if lowerASCII(suffix[i]) != lowerASCII(s[len(s)-len(suffix)+i]) {
+       for i := 0; i < len(s); i++ {
+               if lowerASCII(s[i]) != lowerASCII(t[i]) {
                        return false
                }
        }
        return true
 }
 
-// stringsHasPrefix is strings.HasPrefix. It reports whether s begins with prefix.
-func stringsHasPrefix(s, prefix string) bool {
-       return len(s) >= len(prefix) && s[:len(prefix)] == prefix
-}
-
 func readFull(r io.Reader) (all []byte, err error) {
        buf := make([]byte, 1024)
        for {