mirror of
https://github.com/golang/go
synced 2024-11-19 21:54:40 -07:00
net: don't crash on unexpected DNS SRV responses
Fixes #1350 R=rsc, bradfitzwork CC=golang-dev https://golang.org/cl/4432089
This commit is contained in:
Brad Fitzpatrick
parent
2c92fe0b4f
commit
8ef56f7e92
@ -121,15 +121,19 @@ func answer(name, server string, dns *dnsMsg, qtype uint16) (cname string, addrs
|
||||
Cname:
|
||||
for cnameloop := 0; cnameloop < 10; cnameloop++ {
|
||||
addrs = addrs[0:0]
|
||||
for i := 0; i < len(dns.answer); i++ {
|
||||
rr := dns.answer[i]
|
||||
for _, rr := range dns.answer {
|
||||
if _, justHeader := rr.(*dnsRR_Header); justHeader {
|
||||
// Corrupt record: we only have a
|
||||
// header. That header might say it's
|
||||
// of type qtype, but we don't
|
||||
// actually have it. Skip.
|
||||
continue
|
||||
}
|
||||
h := rr.Header()
|
||||
if h.Class == dnsClassINET && h.Name == name {
|
||||
switch h.Rrtype {
|
||||
case qtype:
|
||||
n := len(addrs)
|
||||
addrs = addrs[0 : n+1]
|
||||
addrs[n] = rr
|
||||
addrs = append(addrs, rr)
|
||||
case dnsTypeCNAME:
|
||||
// redirect to cname
|
||||
name = rr.(*dnsRR_CNAME).Cname
|
||||
@ -181,8 +185,7 @@ func tryOneName(cfg *dnsConfig, name string, qtype uint16) (cname string, addrs
|
||||
|
||||
func convertRR_A(records []dnsRR) []IP {
|
||||
addrs := make([]IP, len(records))
|
||||
for i := 0; i < len(records); i++ {
|
||||
rr := records[i]
|
||||
for i, rr := range records {
|
||||
a := rr.(*dnsRR_A).A
|
||||
addrs[i] = IPv4(byte(a>>24), byte(a>>16), byte(a>>8), byte(a))
|
||||
}
|
||||
@ -191,8 +194,7 @@ func convertRR_A(records []dnsRR) []IP {
|
||||
|
||||
func convertRR_AAAA(records []dnsRR) []IP {
|
||||
addrs := make([]IP, len(records))
|
||||
for i := 0; i < len(records); i++ {
|
||||
rr := records[i]
|
||||
for i, rr := range records {
|
||||
a := make(IP, 16)
|
||||
copy(a, rr.(*dnsRR_AAAA).AAAA[:])
|
||||
addrs[i] = a
|
||||
@ -384,9 +386,7 @@ func goLookupCNAME(name string) (cname string, err os.Error) {
|
||||
if err != nil {
|
||||
return
|
||||
}
|
||||
if len(rr) >= 0 {
|
||||
cname = rr[0].(*dnsRR_CNAME).Cname
|
||||
}
|
||||
cname = rr[0].(*dnsRR_CNAME).Cname
|
||||
return
|
||||
}
|
||||
|
||||
@ -410,8 +410,8 @@ func LookupSRV(service, proto, name string) (cname string, addrs []*SRV, err os.
|
||||
return
|
||||
}
|
||||
addrs = make([]*SRV, len(records))
|
||||
for i := 0; i < len(records); i++ {
|
||||
r := records[i].(*dnsRR_SRV)
|
||||
for i, rr := range records {
|
||||
r := rr.(*dnsRR_SRV)
|
||||
addrs[i] = &SRV{r.Target, r.Port, r.Priority, r.Weight}
|
||||
}
|
||||
return
|
||||
|
||||
@ -715,24 +715,35 @@ func (dns *dnsMsg) Unpack(msg []byte) bool {
|
||||
|
||||
// Arrays.
|
||||
dns.question = make([]dnsQuestion, dh.Qdcount)
|
||||
dns.answer = make([]dnsRR, dh.Ancount)
|
||||
dns.ns = make([]dnsRR, dh.Nscount)
|
||||
dns.extra = make([]dnsRR, dh.Arcount)
|
||||
dns.answer = make([]dnsRR, 0, dh.Ancount)
|
||||
dns.ns = make([]dnsRR, 0, dh.Nscount)
|
||||
dns.extra = make([]dnsRR, 0, dh.Arcount)
|
||||
|
||||
var rec dnsRR
|
||||
|
||||
for i := 0; i < len(dns.question); i++ {
|
||||
off, ok = unpackStruct(&dns.question[i], msg, off)
|
||||
}
|
||||
for i := 0; i < len(dns.answer); i++ {
|
||||
dns.answer[i], off, ok = unpackRR(msg, off)
|
||||
for i := 0; i < int(dh.Ancount); i++ {
|
||||
rec, off, ok = unpackRR(msg, off)
|
||||
if !ok {
|
||||
return false
|
||||
}
|
||||
dns.answer = append(dns.answer, rec)
|
||||
}
|
||||
for i := 0; i < len(dns.ns); i++ {
|
||||
dns.ns[i], off, ok = unpackRR(msg, off)
|
||||
for i := 0; i < int(dh.Nscount); i++ {
|
||||
rec, off, ok = unpackRR(msg, off)
|
||||
if !ok {
|
||||
return false
|
||||
}
|
||||
dns.ns = append(dns.ns, rec)
|
||||
}
|
||||
for i := 0; i < len(dns.extra); i++ {
|
||||
dns.extra[i], off, ok = unpackRR(msg, off)
|
||||
}
|
||||
if !ok {
|
||||
return false
|
||||
for i := 0; i < int(dh.Arcount); i++ {
|
||||
rec, off, ok = unpackRR(msg, off)
|
||||
if !ok {
|
||||
return false
|
||||
}
|
||||
dns.extra = append(dns.extra, rec)
|
||||
}
|
||||
// if off != len(msg) {
|
||||
// println("extra bytes in dns packet", off, "<", len(msg));
|
||||
|
||||
100
src/pkg/net/dnsmsg_test.go
Normal file
100
src/pkg/net/dnsmsg_test.go
Normal file
@ -0,0 +1,100 @@
|
||||
// Copyright 2011 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 (
|
||||
"encoding/hex"
|
||||
"testing"
|
||||
)
|
||||
|
||||
func TestDNSParseSRVReply(t *testing.T) {
|
||||
data, err := hex.DecodeString(dnsSRVReply)
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
msg := new(dnsMsg)
|
||||
ok := msg.Unpack(data)
|
||||
if !ok {
|
||||
t.Fatalf("unpacking packet failed")
|
||||
}
|
||||
if g, e := len(msg.answer), 5; g != e {
|
||||
t.Errorf("len(msg.answer) = %d; want %d", g, e)
|
||||
}
|
||||
for idx, rr := range msg.answer {
|
||||
if g, e := rr.Header().Rrtype, uint16(dnsTypeSRV); g != e {
|
||||
t.Errorf("rr[%d].Header().Rrtype = %d; want %d", idx, g, e)
|
||||
}
|
||||
if _, ok := rr.(*dnsRR_SRV); !ok {
|
||||
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)
|
||||
}
|
||||
}
|
||||
|
||||
func TestDNSParseCorruptSRVReply(t *testing.T) {
|
||||
data, err := hex.DecodeString(dnsSRVCorruptReply)
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
msg := new(dnsMsg)
|
||||
ok := msg.Unpack(data)
|
||||
if !ok {
|
||||
t.Fatalf("unpacking packet failed")
|
||||
}
|
||||
if g, e := len(msg.answer), 5; g != e {
|
||||
t.Errorf("len(msg.answer) = %d; want %d", g, e)
|
||||
}
|
||||
for idx, rr := range msg.answer {
|
||||
if g, e := rr.Header().Rrtype, uint16(dnsTypeSRV); g != e {
|
||||
t.Errorf("rr[%d].Header().Rrtype = %d; want %d", idx, g, e)
|
||||
}
|
||||
if idx == 4 {
|
||||
if _, ok := rr.(*dnsRR_Header); !ok {
|
||||
t.Errorf("answer[%d] = %T; want *dnsRR_Header", idx, rr)
|
||||
}
|
||||
} else {
|
||||
if _, ok := rr.(*dnsRR_SRV); !ok {
|
||||
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), 4; g != e {
|
||||
t.Errorf("len(addrs) = %d; want %d", g, e)
|
||||
t.Logf("addrs = %#v", addrs)
|
||||
}
|
||||
}
|
||||
|
||||
// Valid DNS SRV reply
|
||||
const dnsSRVReply = "0901818000010005000000000c5f786d70702d736572766572045f74637006676f6f67" +
|
||||
"6c6503636f6d0000210001c00c002100010000012c00210014000014950c786d70702d" +
|
||||
"73657276657234016c06676f6f676c6503636f6d00c00c002100010000012c00210014" +
|
||||
"000014950c786d70702d73657276657232016c06676f6f676c6503636f6d00c00c0021" +
|
||||
"00010000012c00210014000014950c786d70702d73657276657233016c06676f6f676c" +
|
||||
"6503636f6d00c00c002100010000012c00200005000014950b786d70702d7365727665" +
|
||||
"72016c06676f6f676c6503636f6d00c00c002100010000012c00210014000014950c78" +
|
||||
"6d70702d73657276657231016c06676f6f676c6503636f6d00"
|
||||
|
||||
// Corrupt DNS SRV reply, with its final RR having a bogus length
|
||||
// (perhaps it was truncated, or it's malicious) The mutation is the
|
||||
// capital "FF" below, instead of the proper "21".
|
||||
const dnsSRVCorruptReply = "0901818000010005000000000c5f786d70702d736572766572045f74637006676f6f67" +
|
||||
"6c6503636f6d0000210001c00c002100010000012c00210014000014950c786d70702d" +
|
||||
"73657276657234016c06676f6f676c6503636f6d00c00c002100010000012c00210014" +
|
||||
"000014950c786d70702d73657276657232016c06676f6f676c6503636f6d00c00c0021" +
|
||||
"00010000012c00210014000014950c786d70702d73657276657233016c06676f6f676c" +
|
||||
"6503636f6d00c00c002100010000012c00200005000014950b786d70702d7365727665" +
|
||||
"72016c06676f6f676c6503636f6d00c00c002100010000012c00FF0014000014950c78" +
|
||||
"6d70702d73657276657231016c06676f6f676c6503636f6d00"
|
||||
Loading…
Reference in New Issue
Block a user