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Unpack: return header (#608) 

When we unpack a message and only have the header consider it a valid
message and don't return an error.
This commit is contained in:
Miek Gieben 2017-12-20 10:51:13 +00:00 committed by GitHub
parent cef5150e02
commit 5f2d7c7013
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2 changed files with 9 additions and 4 deletions
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6
client_test.go
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@ -458,12 +458,12 @@ func TestTruncatedMsg(t *testing.T) {
t.Errorf("error should not be ErrTruncated from question cutoff unpack: %v", err)
}
// Finally, if we only have the header, we should still return an error
// Finally, if we only have the header, we don't return an error.
buf1 = buf[:12]
r = new(Msg)
if err = r.Unpack(buf1); err == nil || err != ErrTruncated {
t.Errorf("error not ErrTruncated from header-only unpack: %v", err)
if err = r.Unpack(buf1); err != nil {
t.Errorf("from header-only unpack should not return an error: %v", err)
}
}

7
msg.go
View File

@ -811,8 +811,13 @@ func (dns *Msg) Unpack(msg []byte) (err error) {
dns.CheckingDisabled = (dh.Bits & _CD) != 0
dns.Rcode = int(dh.Bits & 0xF)
// If we are at the end of the message we should return *just* the
// header. This can still be useful to the caller. 9.9.9.9 sends these
// when responding with REFUSED for instance.
if off == len(msg) {
return ErrTruncated
// reset sections before returning
dns.Question, dns.Answer, dns.Ns, dns.Extra = nil, nil, nil, nil
return nil
}
// Optimistically use the count given to us in the header