9d2301cae2
This diff has been extracted from c2f7ccab0e
See https://github.com/ooni/probe/issues/2096
While there, export DecodeReply to decode a raw reply without
interpreting the Rcode or parsing the results, which seems a
nice extra feature to have to more flexibly parse DNS replies
in other parts of the codebase.
111 lines
2.7 KiB
Go
111 lines
2.7 KiB
Go
package netxlite
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import (
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"errors"
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"github.com/miekg/dns"
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"github.com/ooni/probe-cli/v3/internal/model"
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)
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// DNSDecoderMiekg uses github.com/miekg/dns to implement the Decoder.
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type DNSDecoderMiekg struct{}
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// ErrDNSReplyWithWrongQueryID indicates we have got a DNS reply with the wrong queryID.
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var ErrDNSReplyWithWrongQueryID = errors.New(FailureDNSReplyWithWrongQueryID)
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// DecodeReply implements model.DNSDecoder.DecodeReply
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func (d *DNSDecoderMiekg) DecodeReply(data []byte) (*dns.Msg, error) {
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reply := new(dns.Msg)
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if err := reply.Unpack(data); err != nil {
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return nil, err
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}
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return reply, nil
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}
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func (d *DNSDecoderMiekg) parseReply(data []byte, queryID uint16) (*dns.Msg, error) {
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reply, err := d.DecodeReply(data)
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if err != nil {
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return nil, err
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}
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if reply.Id != queryID {
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return nil, ErrDNSReplyWithWrongQueryID
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}
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// TODO(bassosimone): map more errors to net.DNSError names
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// TODO(bassosimone): add support for lame referral.
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switch reply.Rcode {
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case dns.RcodeSuccess:
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return reply, nil
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case dns.RcodeNameError:
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return nil, ErrOODNSNoSuchHost
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case dns.RcodeRefused:
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return nil, ErrOODNSRefused
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case dns.RcodeServerFailure:
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return nil, ErrOODNSServfail
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default:
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return nil, ErrOODNSMisbehaving
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}
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}
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func (d *DNSDecoderMiekg) DecodeHTTPS(data []byte, queryID uint16) (*model.HTTPSSvc, error) {
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reply, err := d.parseReply(data, queryID)
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if err != nil {
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return nil, err
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}
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out := &model.HTTPSSvc{
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ALPN: []string{}, // ensure it's not nil
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IPv4: []string{}, // ensure it's not nil
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IPv6: []string{}, // ensure it's not nil
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}
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for _, answer := range reply.Answer {
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switch avalue := answer.(type) {
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case *dns.HTTPS:
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for _, v := range avalue.Value {
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switch extv := v.(type) {
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case *dns.SVCBAlpn:
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out.ALPN = extv.Alpn
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case *dns.SVCBIPv4Hint:
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for _, ip := range extv.Hint {
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out.IPv4 = append(out.IPv4, ip.String())
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}
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case *dns.SVCBIPv6Hint:
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for _, ip := range extv.Hint {
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out.IPv6 = append(out.IPv6, ip.String())
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}
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}
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}
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}
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}
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if len(out.IPv4) <= 0 && len(out.IPv6) <= 0 {
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return nil, ErrOODNSNoAnswer
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}
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return out, nil
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}
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func (d *DNSDecoderMiekg) DecodeLookupHost(qtype uint16, data []byte, queryID uint16) ([]string, error) {
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reply, err := d.parseReply(data, queryID)
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if err != nil {
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return nil, err
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}
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var addrs []string
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for _, answer := range reply.Answer {
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switch qtype {
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case dns.TypeA:
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if rra, ok := answer.(*dns.A); ok {
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ip := rra.A
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addrs = append(addrs, ip.String())
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}
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case dns.TypeAAAA:
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if rra, ok := answer.(*dns.AAAA); ok {
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ip := rra.AAAA
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addrs = append(addrs, ip.String())
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}
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}
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}
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if len(addrs) <= 0 {
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return nil, ErrOODNSNoAnswer
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}
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return addrs, nil
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}
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var _ model.DNSDecoder = &DNSDecoderMiekg{}
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