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net: allow a dns TXT record to contain more than one <character-string>

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RFC 1035 3.3.14 allows a TXT record to contain one or more <character-string>s.
The current implementation returns a "no such host" error if there is more
than one <character-string> in the TXT record.

Fixes #10482

Change-Id: I0ded258005e6b7ba45f687fecd10afa2b321bb77
Reviewed-on: https://go-review.googlesource.com/8966
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
This commit is contained in:
tnt 2015-04-16 22:18:36 +02:00 • committed by Ian Lance Taylor
parent d12b532265
commit bfb077e0ee
2 changed files with 164 additions and 1 deletions
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18
src/net/dnsmsg.go
View file

@ -306,7 +306,23 @@ func (rr *dnsRR_TXT) Header() *dnsRR_Header {
}
func (rr *dnsRR_TXT) Walk(f func(v interface{}, name, tag string) bool) bool {
return rr.Hdr.Walk(f) && f(&rr.Txt, "Txt", "")
if !rr.Hdr.Walk(f) {
return false
}
var n uint16 = 0
for n < rr.Hdr.Rdlength {
var txt string
if !f(&txt, "Txt", "") {
return false
}
// more bytes than rr.Hdr.Rdlength said there woudld be
if rr.Hdr.Rdlength-n < uint16(len(txt))+1 {
return false
}
n += uint16(len(txt)) + 1
rr.Txt += txt
}
return true
}
type dnsRR_SRV struct {

147
src/net/dnsmsg_test.go
View file

@ -96,6 +96,93 @@ func TestDNSParseCorruptSRVReply(t *testing.T) {
}
}
func TestDNSParseTXTReply(t *testing.T) {
expectedTxt1 := "v=spf1 redirect=_spf.google.com"
expectedTxt2 := "v=spf1 ip4:69.63.179.25 ip4:69.63.178.128/25 ip4:69.63.184.0/25 " +
"ip4:66.220.144.128/25 ip4:66.220.155.0/24 " +
"ip4:69.171.232.0/25 ip4:66.220.157.0/25 " +
"ip4:69.171.244.0/24 mx -all"
replies := []string{dnsTXTReply1, dnsTXTReply2}
expectedTxts := []string{expectedTxt1, expectedTxt2}
for i := range replies {
data, err := hex.DecodeString(replies[i])
if err != nil {
t.Fatal(err)
}
msg := new(dnsMsg)
ok := msg.Unpack(data)
if !ok {
t.Errorf("test %d: unpacking packet failed", i)
continue
}
if len(msg.answer) != 1 {
t.Errorf("test %d: len(rr.answer) = %d; want 1", i, len(msg.answer))
continue
}
rr := msg.answer[0]
rrTXT, ok := rr.(*dnsRR_TXT)
if !ok {
t.Errorf("test %d: answer[0] = %T; want *dnsRR_TXT", i, rr)
continue
}
if rrTXT.Txt != expectedTxts[i] {
t.Errorf("test %d: Txt = %s; want %s", i, rrTXT.Txt, expectedTxts[i])
}
}
}
func TestDNSParseTXTCorruptDataLengthReply(t *testing.T) {
replies := []string{dnsTXTCorruptDataLengthReply1, dnsTXTCorruptDataLengthReply2}
for i := range replies {
data, err := hex.DecodeString(replies[i])
if err != nil {
t.Fatal(err)
}
msg := new(dnsMsg)
ok := msg.Unpack(data)
if ok {
t.Errorf("test %d: expected to fail on unpacking corrupt packet", i)
}
}
}
func TestDNSParseTXTCorruptTXTLengthReply(t *testing.T) {
replies := []string{dnsTXTCorruptTXTLengthReply1, dnsTXTCorruptTXTLengthReply2}
for i := range replies {
data, err := hex.DecodeString(replies[i])
if err != nil {
t.Fatal(err)
}
msg := new(dnsMsg)
ok := msg.Unpack(data)
// Unpacking should succeed, but we should just get the header.
if !ok {
t.Errorf("test %d: unpacking packet failed", i)
continue
}
if len(msg.answer) != 1 {
t.Errorf("test %d: len(rr.answer) = %d; want 1", i, len(msg.answer))
continue
}
rr := msg.answer[0]
if _, justHeader := rr.(*dnsRR_Header); !justHeader {
t.Errorf("test %d: rr = %T; expected *dnsRR_Header", i, rr)
}
}
}
// Valid DNS SRV reply
const dnsSRVReply = "0901818000010005000000000c5f786d70702d736572766572045f74637006676f6f67" +
"6c6503636f6d0000210001c00c002100010000012c00210014000014950c786d70702d" +
@ -117,3 +204,63 @@ const dnsSRVCorruptReply = "0901818000010005000000000c5f786d70702d73657276657204
"6503636f6d00c00c002100010000012c00200005000014950b786d70702d7365727665" +
"72016c06676f6f676c6503636f6d00c00c002100010000012c00FF0014000014950c78" +
"6d70702d73657276657231016c06676f6f676c6503636f6d00"
// TXT reply with one <character-string>
const dnsTXTReply1 = "b3458180000100010004000505676d61696c03636f6d0000100001c00c001000010000012c00" +
"201f763d737066312072656469726563743d5f7370662e676f6f676c652e636f6dc00" +
"c0002000100025d4c000d036e733406676f6f676c65c012c00c0002000100025d4c00" +
"06036e7331c057c00c0002000100025d4c0006036e7333c057c00c0002000100025d4" +
"c0006036e7332c057c06c00010001000248b50004d8ef200ac09000010001000248b5" +
"0004d8ef220ac07e00010001000248b50004d8ef240ac05300010001000248b50004d" +
"8ef260a0000291000000000000000"
// TXT reply with more than one <character-string>.
// See https://tools.ietf.org/html/rfc1035#section-3.3.14
const dnsTXTReply2 = "a0a381800001000100020002045f7370660866616365626f6f6b03636f6d0000100001c00c0010000" +
"100000e1000af7f763d73706631206970343a36392e36332e3137392e3235206970343a36392e" +
"36332e3137382e3132382f3235206970343a36392e36332e3138342e302f3235206970343a363" +
"62e3232302e3134342e3132382f3235206970343a36362e3232302e3135352e302f3234206970" +
"343a36392e3137312e3233322e302f323520692e70343a36362e3232302e3135372e302f32352" +
"06970343a36392e3137312e3234342e302f3234206d78202d616c6cc0110002000100025d1500" +
"070161026e73c011c0110002000100025d1500040162c0ecc0ea0001000100025d15000445abe" +
"f0cc0fd0001000100025d15000445abff0c"
// DataLength field should be sum of all TXT fields. In this case it's less.
const dnsTXTCorruptDataLengthReply1 = "a0a381800001000100020002045f7370660866616365626f6f6b03636f6d0000100001c00c0010000" +
"100000e1000967f763d73706631206970343a36392e36332e3137392e3235206970343a36392e" +
"36332e3137382e3132382f3235206970343a36392e36332e3138342e302f3235206970343a363" +
"62e3232302e3134342e3132382f3235206970343a36362e3232302e3135352e302f3234206970" +
"343a36392e3137312e3233322e302f323520692e70343a36362e3232302e3135372e302f32352" +
"06970343a36392e3137312e3234342e302f3234206d78202d616c6cc0110002000100025d1500" +
"070161026e73c011c0110002000100025d1500040162c0ecc0ea0001000100025d15000445abe" +
"f0cc0fd0001000100025d15000445abff0c"
// Same as above but DataLength is more than sum of TXT fields.
const dnsTXTCorruptDataLengthReply2 = "a0a381800001000100020002045f7370660866616365626f6f6b03636f6d0000100001c00c0010000" +
"100000e1001227f763d73706631206970343a36392e36332e3137392e3235206970343a36392e" +
"36332e3137382e3132382f3235206970343a36392e36332e3138342e302f3235206970343a363" +
"62e3232302e3134342e3132382f3235206970343a36362e3232302e3135352e302f3234206970" +
"343a36392e3137312e3233322e302f323520692e70343a36362e3232302e3135372e302f32352" +
"06970343a36392e3137312e3234342e302f3234206d78202d616c6cc0110002000100025d1500" +
"070161026e73c011c0110002000100025d1500040162c0ecc0ea0001000100025d15000445abe" +
"f0cc0fd0001000100025d15000445abff0c"
// TXT Length field is less than actual length.
const dnsTXTCorruptTXTLengthReply1 = "a0a381800001000100020002045f7370660866616365626f6f6b03636f6d0000100001c00c0010000" +
"100000e1000af7f763d73706631206970343a36392e36332e3137392e3235206970343a36392e" +
"36332e3137382e3132382f3235206970343a36392e36332e3138342e302f3235206970343a363" +
"62e3232302e3134342e3132382f3235206970343a36362e3232302e3135352e302f3234206970" +
"343a36392e3137312e3233322e302f323520691470343a36362e3232302e3135372e302f32352" +
"06970343a36392e3137312e3234342e302f3234206d78202d616c6cc0110002000100025d1500" +
"070161026e73c011c0110002000100025d1500040162c0ecc0ea0001000100025d15000445abe" +
"f0cc0fd0001000100025d15000445abff0c"
// TXT Length field is more than actual length.
const dnsTXTCorruptTXTLengthReply2 = "a0a381800001000100020002045f7370660866616365626f6f6b03636f6d0000100001c00c0010000" +
"100000e1000af7f763d73706631206970343a36392e36332e3137392e3235206970343a36392e" +
"36332e3137382e3132382f3235206970343a36392e36332e3138342e302f3235206970343a363" +
"62e3232302e3134342e3132382f3235206970343a36362e3232302e3135352e302f3234206970" +
"343a36392e3137312e3233322e302f323520693370343a36362e3232302e3135372e302f32352" +
"06970343a36392e3137312e3234342e302f3234206d78202d616c6cc0110002000100025d1500" +
"070161026e73c011c0110002000100025d1500040162c0ecc0ea0001000100025d15000445abe" +
"f0cc0fd0001000100025d15000445abff0c"