net: fix LookupSRV

R=rsc, chris
CC=golang-dev
https://golang.org/cl/2420041

diff --git a/src/pkg/net/dnsclient.go b/src/pkg/net/dnsclient.go
index accee63890fc381f6158c5853bf1bfe9535b5a51..f1cd47bb19c9cb5baa99c9b5f5b70cac670f2c6f 100644 (file)
--- a/src/pkg/net/dnsclient.go
+++ b/src/pkg/net/dnsclient.go
@@ -196,12 +196,16 @@ func isDomainName(s string) bool {
        if len(s) == 0 {
                return false
        }
+       if len(s) > 255 {
+               return false
+       }
        if s[len(s)-1] != '.' { // simplify checking loop: make name end in dot
                s += "."
        }
 
        last := byte('.')
        ok := false // ok once we've seen a letter
+       partlen := 0
        for i := 0; i < len(s); i++ {
                c := s[i]
                switch {
@@ -209,18 +213,25 @@ func isDomainName(s string) bool {
                        return false
                case 'a' <= c && c <= 'z' || 'A' <= c && c <= 'Z' || c == '_':
                        ok = true
+                       partlen++
                case '0' <= c && c <= '9':
                        // fine
+                       partlen++
                case c == '-':
                        // byte before dash cannot be dot
                        if last == '.' {
                                return false
                        }
+                       partlen++
                case c == '.':
                        // byte before dot cannot be dot, dash
                        if last == '.' || last == '-' {
                                return false
                        }
+                       if partlen > 63 || partlen == 0 {
+                               return false
+                       }
+                       partlen = 0
                }
                last = c
        }
@@ -315,9 +326,14 @@ type SRV struct {
        Weight   uint16
 }
 
-func LookupSRV(name string) (cname string, addrs []*SRV, err os.Error) {
+// LookupSRV tries to resolve an SRV query of the given service,
+// protocol, and domain name, as specified in RFC 2782. In most cases
+// the proto argument can be the same as the corresponding
+// Addr.Network().
+func LookupSRV(service, proto, name string) (cname string, addrs []*SRV, err os.Error) {
+       target := "_" + service + "._" + proto + "." + name
        var records []dnsRR
-       cname, records, err = lookup(name, dnsTypeSRV)
+       cname, records, err = lookup(target, dnsTypeSRV)
        if err != nil {
                return
        }

diff --git a/src/pkg/net/dnsname_test.go b/src/pkg/net/dnsname_test.go
new file mode 100644 (file)
index 0000000..67acc87
--- /dev/null
+++ b/src/pkg/net/dnsname_test.go
@@ -0,0 +1,65 @@
+// Copyright 2009 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 (
+       "testing"
+)
+
+type testCase struct {
+       name   string
+       result bool
+}
+
+var tests = []testCase{
+       // RFC2181, section 11.
+       testCase{"_xmpp-server._tcp.google.com", true},
+       testCase{"_xmpp-server._tcp.google.com", true},
+       testCase{"foo.com", true},
+       testCase{"1foo.com", true},
+       testCase{"26.0.0.73.com", true},
+       testCase{"fo-o.com", true},
+       testCase{"fo1o.com", true},
+       testCase{"foo1.com", true},
+       testCase{"a.b..com", false},
+}
+
+func getTestCases(ch chan<- *testCase) {
+       defer close(ch)
+       var char59 = ""
+       var char63 = ""
+       var char64 = ""
+       for i := 0; i < 59; i++ {
+               char59 += "a"
+       }
+       char63 = char59 + "aaaa"
+       char64 = char63 + "a"
+
+       for _, tc := range tests {
+               ch <- &tc
+       }
+
+       ch <- &testCase{char63 + ".com", true}
+       ch <- &testCase{char64 + ".com", false}
+       // 255 char name is fine:
+       ch <- &testCase{char59 + "." + char63 + "." + char63 + "." +
+               char63 + ".com",
+               true}
+       // 256 char name is bad:
+       ch <- &testCase{char59 + "a." + char63 + "." + char63 + "." +
+               char63 + ".com",
+               false}
+}
+
+func TestDNSNames(t *testing.T) {
+       ch := make(chan *testCase)
+       go getTestCases(ch)
+       for tc := range ch {
+               if isDomainName(tc.name) != tc.result {
+                       t.Errorf("isDomainName(%v) failed: Should be %v",
+                               tc.name, tc.result)
+               }
+       }
+}

diff --git a/src/pkg/net/srv_test.go b/src/pkg/net/srv_test.go
new file mode 100644 (file)
index 0000000..4dd6089
--- /dev/null
+++ b/src/pkg/net/srv_test.go
@@ -0,0 +1,22 @@
+// Copyright 2009 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.
+
+// TODO It would be nice to use a mock DNS server, to eliminate
+// external dependencies.
+
+package net
+
+import (
+       "testing"
+)
+
+func TestGoogleSRV(t *testing.T) {
+       _, addrs, err := LookupSRV("xmpp-server", "tcp", "google.com")
+       if err != nil {
+               t.Errorf("failed: %s", err)
+       }
+       if len(addrs) == 0 {
+               t.Errorf("no results")
+       }
+}