fix(nextlite): wrap DNSDecoder errors (#962)

The simplest fix is to wrap such errors in dnsdecoder.go.

Fixes https://github.com/ooni/probe/issues/2317.

internal/netxlite/dnsdecoder.go

@@ -23,17 +23,22 @@ var (
 	ErrDNSIsQuery = errors.New("ooresolver: expected response but received query")
 )
 
+// dnsDecoderWrapError ensures we wrap the returned errors
+func dnsDecoderWrapError(err error) error {
+	return MaybeNewErrWrapper(ClassifyResolverError, ResolveOperation, err)
+}
+
 // DecodeResponse implements model.DNSDecoder.DecodeResponse.
 func (d *DNSDecoderMiekg) DecodeResponse(data []byte, query model.DNSQuery) (model.DNSResponse, error) {
 	reply := &dns.Msg{}
 	if err := reply.Unpack(data); err != nil {
-		return nil, err
+		return nil, dnsDecoderWrapError(err)
 	}
 	if !reply.Response {
-		return nil, ErrDNSIsQuery
+		return nil, dnsDecoderWrapError(ErrDNSIsQuery)
 	}
 	if reply.Id != query.ID() {
-		return nil, ErrDNSReplyWithWrongQueryID
+		return nil, dnsDecoderWrapError(ErrDNSReplyWithWrongQueryID)
 	}
 	resp := &dnsResponse{
 		bytes: data,
@@ -77,20 +82,20 @@ func (r *dnsResponse) rcodeToError() error {
 	case dns.RcodeSuccess:
 		return nil
 	case dns.RcodeNameError:
-		return ErrOODNSNoSuchHost
+		return dnsDecoderWrapError(ErrOODNSNoSuchHost)
 	case dns.RcodeRefused:
-		return ErrOODNSRefused
+		return dnsDecoderWrapError(ErrOODNSRefused)
 	case dns.RcodeServerFailure:
-		return ErrOODNSServfail
+		return dnsDecoderWrapError(ErrOODNSServfail)
 	default:
-		return ErrOODNSMisbehaving
+		return dnsDecoderWrapError(ErrOODNSMisbehaving)
 	}
 }
 
 // DecodeHTTPS implements model.DNSResponse.DecodeHTTPS.
 func (r *dnsResponse) DecodeHTTPS() (*model.HTTPSSvc, error) {
 	if err := r.rcodeToError(); err != nil {
-		return nil, err
+		return nil, err // error already wrapped
 	}
 	out := &model.HTTPSSvc{
 		ALPN: []string{}, // ensure it's not nil
@@ -117,7 +122,7 @@ func (r *dnsResponse) DecodeHTTPS() (*model.HTTPSSvc, error) {
 		}
 	}
 	if len(out.IPv4) <= 0 && len(out.IPv6) <= 0 {
-		return nil, ErrOODNSNoAnswer
+		return nil, dnsDecoderWrapError(ErrOODNSNoAnswer)
 	}
 	return out, nil
 }
@@ -125,7 +130,7 @@ func (r *dnsResponse) DecodeHTTPS() (*model.HTTPSSvc, error) {
 // DecodeLookupHost implements model.DNSResponse.DecodeLookupHost.
 func (r *dnsResponse) DecodeLookupHost() ([]string, error) {
 	if err := r.rcodeToError(); err != nil {
-		return nil, err
+		return nil, err // error already wrapped
 	}
 	var addrs []string
 	for _, answer := range r.msg.Answer {
@@ -143,7 +148,7 @@ func (r *dnsResponse) DecodeLookupHost() ([]string, error) {
 		}
 	}
 	if len(addrs) <= 0 {
-		return nil, ErrOODNSNoAnswer
+		return nil, dnsDecoderWrapError(ErrOODNSNoAnswer)
 	}
 	return addrs, nil
 }
@@ -151,7 +156,7 @@ func (r *dnsResponse) DecodeLookupHost() ([]string, error) {
 // DecodeNS implements model.DNSResponse.DecodeNS.
 func (r *dnsResponse) DecodeNS() ([]*net.NS, error) {
 	if err := r.rcodeToError(); err != nil {
-		return nil, err
+		return nil, err // error already wrapped
 	}
 	out := []*net.NS{}
 	for _, answer := range r.msg.Answer {
@@ -161,7 +166,7 @@ func (r *dnsResponse) DecodeNS() ([]*net.NS, error) {
 		}
 	}
 	if len(out) < 1 {
-		return nil, ErrOODNSNoAnswer
+		return nil, dnsDecoderWrapError(ErrOODNSNoAnswer)
 	}
 	return out, nil
 }
@@ -169,7 +174,7 @@ func (r *dnsResponse) DecodeNS() ([]*net.NS, error) {
 // DecodeCNAME implements model.DNSResponse.DecodeCNAME.
 func (r *dnsResponse) DecodeCNAME() (string, error) {
 	if err := r.rcodeToError(); err != nil {
-		return "", err
+		return "", err // error already wrapped
 	}
 	for _, answer := range r.msg.Answer {
 		switch avalue := answer.(type) {
@@ -177,7 +182,7 @@ func (r *dnsResponse) DecodeCNAME() (string, error) {
 			return avalue.Target, nil
 		}
 	}
-	return "", ErrOODNSNoAnswer
+	return "", dnsDecoderWrapError(ErrOODNSNoAnswer)
 }
 
 var _ model.DNSDecoder = &DNSDecoderMiekg{}

internal/netxlite/dnsdecoder_test.go

@@ -12,14 +12,22 @@ import (
 	"github.com/ooni/probe-cli/v3/internal/runtimex"
 )
 
+func dnsDecoderErrorIsWrapped(err error) bool {
+	var errwrapper *ErrWrapper
+	return errors.As(err, &errwrapper)
+}
+
 func TestDNSDecoderMiekg(t *testing.T) {
 	t.Run("DecodeResponse", func(t *testing.T) {
 		t.Run("UnpackError", func(t *testing.T) {
 			d := &DNSDecoderMiekg{}
 			resp, err := d.DecodeResponse(nil, &mocks.DNSQuery{})
-			if err == nil || err.Error() != "dns: overflow unpacking uint16" {
+			if err == nil || err.Error() != "unknown_failure: dns: overflow unpacking uint16" {
 				t.Fatal("unexpected error", err)
 			}
+			if !dnsDecoderErrorIsWrapped(err) {
+				t.Fatal("unwrapped error", err)
+			}
 			if resp != nil {
 				t.Fatal("expected nil resp here")
 			}
@@ -33,6 +41,9 @@ func TestDNSDecoderMiekg(t *testing.T) {
 			if !errors.Is(err, ErrDNSIsQuery) {
 				t.Fatal("unexpected err", err)
 			}
+			if !dnsDecoderErrorIsWrapped(err) {
+				t.Fatal("unwrapped error", err)
+			}
 			if resp != nil {
 				t.Fatal("expected nil resp here")
 			}
@@ -53,6 +64,9 @@ func TestDNSDecoderMiekg(t *testing.T) {
 			if !errors.Is(err, ErrDNSReplyWithWrongQueryID) {
 				t.Fatal("unexpected error", err)
 			}
+			if !dnsDecoderErrorIsWrapped(err) {
+				t.Fatal("unwrapped error", err)
+			}
 			if resp != nil {
 				t.Fatal("expected nil resp here")
 			}
@@ -163,6 +177,9 @@ func TestDNSDecoderMiekg(t *testing.T) {
 					if !errors.Is(err, io.err) {
 						t.Fatal("unexpected err", err)
 					}
+					if err != nil && !dnsDecoderErrorIsWrapped(err) {
+						t.Fatal("unwrapped error", err)
+					}
 				})
 			}
 		})
@@ -187,6 +204,9 @@ func TestDNSDecoderMiekg(t *testing.T) {
 				if !errors.Is(err, ErrOODNSRefused) {
 					t.Fatal("unexpected err", err)
 				}
+				if !dnsDecoderErrorIsWrapped(err) {
+					t.Fatal("unwrapped error", err)
+				}
 				if https != nil {
 					t.Fatal("expected nil https result")
 				}
@@ -210,6 +230,9 @@ func TestDNSDecoderMiekg(t *testing.T) {
 				if !errors.Is(err, ErrOODNSNoAnswer) {
 					t.Fatal("unexpected err", err)
 				}
+				if !dnsDecoderErrorIsWrapped(err) {
+					t.Fatal("unwrapped error", err)
+				}
 				if https != nil {
 					t.Fatal("expected nil https results")
 				}
@@ -268,6 +291,9 @@ func TestDNSDecoderMiekg(t *testing.T) {
 				if !errors.Is(err, ErrOODNSRefused) {
 					t.Fatal("unexpected err", err)
 				}
+				if !dnsDecoderErrorIsWrapped(err) {
+					t.Fatal("unwrapped error", err)
+				}
 				if len(ns) > 0 {
 					t.Fatal("expected empty ns result")
 				}
@@ -291,6 +317,9 @@ func TestDNSDecoderMiekg(t *testing.T) {
 				if !errors.Is(err, ErrOODNSNoAnswer) {
 					t.Fatal("unexpected err", err)
 				}
+				if !dnsDecoderErrorIsWrapped(err) {
+					t.Fatal("unwrapped error", err)
+				}
 				if len(ns) > 0 {
 					t.Fatal("expected empty ns results")
 				}
@@ -343,6 +372,9 @@ func TestDNSDecoderMiekg(t *testing.T) {
 				if !errors.Is(err, ErrOODNSRefused) {
 					t.Fatal("unexpected err", err)
 				}
+				if !dnsDecoderErrorIsWrapped(err) {
+					t.Fatal("unwrapped error", err)
+				}
 				if len(addrs) > 0 {
 					t.Fatal("expected empty addrs result")
 				}
@@ -366,6 +398,9 @@ func TestDNSDecoderMiekg(t *testing.T) {
 				if !errors.Is(err, ErrOODNSNoAnswer) {
 					t.Fatal("unexpected err", err)
 				}
+				if !dnsDecoderErrorIsWrapped(err) {
+					t.Fatal("unwrapped error", err)
+				}
 				if len(addrs) > 0 {
 					t.Fatal("expected empty ns results")
 				}
@@ -456,6 +491,9 @@ func TestDNSDecoderMiekg(t *testing.T) {
 				if !errors.Is(err, ErrOODNSNoAnswer) {
 					t.Fatal("not the error we expected", err)
 				}
+				if !dnsDecoderErrorIsWrapped(err) {
+					t.Fatal("unwrapped error", err)
+				}
 				if len(addrs) > 0 {
 					t.Fatal("expected no addrs here")
 				}
@@ -482,6 +520,9 @@ func TestDNSDecoderMiekg(t *testing.T) {
 				if !errors.Is(err, ErrOODNSNoAnswer) {
 					t.Fatal("not the error we expected", err)
 				}
+				if !dnsDecoderErrorIsWrapped(err) {
+					t.Fatal("unwrapped error", err)
+				}
 				if len(addrs) > 0 {
 					t.Fatal("expected no addrs here")
 				}
@@ -532,6 +573,9 @@ func TestDNSDecoderMiekg(t *testing.T) {
 				if !errors.Is(err, ErrOODNSNoAnswer) {
 					t.Fatal("unexpected err", err)
 				}
+				if !dnsDecoderErrorIsWrapped(err) {
+					t.Fatal("unwrapped error", err)
+				}
 				if cname != "" {
 					t.Fatal("expected empty cname result")
 				}