ooni-probe-cli/internal/netxlite/dnsdecoder.go
Simone Basso 5904e6988d
fix(netxlite): map servfail error (#728)
This error occurred for example when querying kazemjalali.com
in websteps measurements run from Iran.

This error is relatively uncommon, but it still makes sense to
create a specific mapping rule for it.

Originally: 4269e82fbd

See https://github.com/ooni/probe/issues/2096
2022-05-13 19:25:22 +02:00

94 lines
2.2 KiB
Go

package netxlite
import (
"github.com/miekg/dns"
"github.com/ooni/probe-cli/v3/internal/model"
)
// DNSDecoderMiekg uses github.com/miekg/dns to implement the Decoder.
type DNSDecoderMiekg struct{}
func (d *DNSDecoderMiekg) parseReply(data []byte) (*dns.Msg, error) {
reply := new(dns.Msg)
if err := reply.Unpack(data); err != nil {
return nil, err
}
// TODO(bassosimone): map more errors to net.DNSError names
// TODO(bassosimone): add support for lame referral.
switch reply.Rcode {
case dns.RcodeSuccess:
return reply, nil
case dns.RcodeNameError:
return nil, ErrOODNSNoSuchHost
case dns.RcodeRefused:
return nil, ErrOODNSRefused
case dns.RcodeServerFailure:
return nil, ErrOODNSServfail
default:
return nil, ErrOODNSMisbehaving
}
}
func (d *DNSDecoderMiekg) DecodeHTTPS(data []byte) (*model.HTTPSSvc, error) {
reply, err := d.parseReply(data)
if err != nil {
return nil, err
}
out := &model.HTTPSSvc{
ALPN: []string{}, // ensure it's not nil
IPv4: []string{}, // ensure it's not nil
IPv6: []string{}, // ensure it's not nil
}
for _, answer := range reply.Answer {
switch avalue := answer.(type) {
case *dns.HTTPS:
for _, v := range avalue.Value {
switch extv := v.(type) {
case *dns.SVCBAlpn:
out.ALPN = extv.Alpn
case *dns.SVCBIPv4Hint:
for _, ip := range extv.Hint {
out.IPv4 = append(out.IPv4, ip.String())
}
case *dns.SVCBIPv6Hint:
for _, ip := range extv.Hint {
out.IPv6 = append(out.IPv6, ip.String())
}
}
}
}
}
if len(out.IPv4) <= 0 && len(out.IPv6) <= 0 {
return nil, ErrOODNSNoAnswer
}
return out, nil
}
func (d *DNSDecoderMiekg) DecodeLookupHost(qtype uint16, data []byte) ([]string, error) {
reply, err := d.parseReply(data)
if err != nil {
return nil, err
}
var addrs []string
for _, answer := range reply.Answer {
switch qtype {
case dns.TypeA:
if rra, ok := answer.(*dns.A); ok {
ip := rra.A
addrs = append(addrs, ip.String())
}
case dns.TypeAAAA:
if rra, ok := answer.(*dns.AAAA); ok {
ip := rra.AAAA
addrs = append(addrs, ip.String())
}
}
}
if len(addrs) <= 0 {
return nil, ErrOODNSNoAnswer
}
return addrs, nil
}
var _ model.DNSDecoder = &DNSDecoderMiekg{}