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net: case insensitivity of DNS labels in built-in stub resolver

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This change adds support for case insensitivity of DNS labels to
built-in DNS stub resolver as described in RFC 4343.

Fixes #9215.

Change-Id: Ia752fe71866a3bfa3ea08371985b799d419ddea3
Reviewed-on: https://go-review.googlesource.com/3685
Reviewed-by: Ian Lance Taylor <iant@golang.org>
This commit is contained in:
Mikio Hara 2015-02-02 21:09:23 +09:00
parent 77067c1697
commit 826fa06189
2 changed files with 37 additions and 11 deletions
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22
src/net/dnsclient.go
View File

@ -94,7 +94,7 @@ Cname:
continue
}
h := rr.Header()
if h.Class == dnsClassINET && h.Name == name {
if h.Class == dnsClassINET && equalASCIILabel(h.Name, name) {
switch h.Rrtype {
case qtype:
addrs = append(addrs, rr)
@ -114,6 +114,26 @@ Cname:
return "", nil, &DNSError{Err: "too many redirects", Name: name, Server: server}
}
func equalASCIILabel(x, y string) bool {
if len(x) != len(y) {
return false
}
for i := 0; i < len(x); i++ {
a := x[i]
b := y[i]
if 'A' <= a && a <= 'Z' {
a += 0x20
}
if 'A' <= b && b <= 'Z' {
b += 0x20
}
if a != b {
return false
}
}
return true
}
func isDomainName(s string) bool {
// See RFC 1035, RFC 3696.
if len(s) == 0 {

26
src/net/dnsmsg_test.go
View File

@ -18,7 +18,7 @@ func TestDNSParseSRVReply(t *testing.T) {
msg := new(dnsMsg)
ok := msg.Unpack(data)
if !ok {
t.Fatalf("unpacking packet failed")
t.Fatal("unpacking packet failed")
}
msg.String() // exercise this code path
if g, e := len(msg.answer), 5; g != e {
@ -32,13 +32,19 @@ func TestDNSParseSRVReply(t *testing.T) {
t.Errorf("answer[%d] = %T; want *dnsRR_SRV", idx, rr)
}
}
_, addrs, err := answer("_xmpp-server._tcp.google.com.", "foo:53", msg, uint16(dnsTypeSRV))
if err != nil {
t.Fatalf("answer: %v", err)
}
if g, e := len(addrs), 5; g != e {
t.Errorf("len(addrs) = %d; want %d", g, e)
t.Logf("addrs = %#v", addrs)
for _, name := range [...]string{
"_xmpp-server._tcp.google.com.",
"_XMPP-Server._TCP.Google.COM.",
"_XMPP-SERVER._TCP.GOOGLE.COM.",
} {
_, addrs, err := answer(name, "foo:53", msg, uint16(dnsTypeSRV))
if err != nil {
t.Error(err)
}
if g, e := len(addrs), 5; g != e {
t.Errorf("len(addrs) = %d; want %d", g, e)
t.Logf("addrs = %#v", addrs)
}
}
// repack and unpack.
data2, ok := msg.Pack()
@ -46,9 +52,9 @@ func TestDNSParseSRVReply(t *testing.T) {
msg2.Unpack(data2)
switch {
case !ok:
t.Errorf("failed to repack message")
t.Error("failed to repack message")
case !reflect.DeepEqual(msg, msg2):
t.Errorf("repacked message differs from original")
t.Error("repacked message differs from original")
}
}