propagate status errors

.golangci.yml

@@ -3,15 +3,12 @@ run:
 linters:
   disable-all: true
   enable:
-  - deadcode
   - gosimple
   - govet
   - ineffassign
   - staticcheck
-  - structcheck
   - typecheck
   - unused
-  - varcheck
   - gofmt
   - revive
   - gci

doh/client.go

@@ -4,7 +4,6 @@ import (
 	"bytes"
 	"context"
 	"encoding/base64"
-	"errors"
 	"fmt"
 	"net/http"
 
@@ -68,7 +67,7 @@ func (dc *Client) send(r *http.Request) (*dns.Msg, error) {
 	defer resp.Body.Close()
 
 	if resp.StatusCode != http.StatusOK {
-		return nil, errors.New("unexpected HTTP status")
+		return nil, UnexpectedServerHTTPStatusError{code: resp.StatusCode}
 	}
 
 	buffer := bytes.Buffer{}

doh/client_test.go

@@ -1,4 +1,4 @@
-package doh
+package doh_test
 
 import (
 	"context"
@@ -11,11 +11,13 @@ import (
 	"github.com/miekg/dns"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
+	"github.com/tantalor93/doh-go/doh"
 )
 
 const (
 	existingDomain    = "google.com."
 	notExistingDomain = "nxdomain.cz."
+	badStatusDomain   = "wrong.com."
 )
 
 func Test_SendViaPost(t *testing.T) {
@@ -37,6 +39,9 @@ func Test_SendViaPost(t *testing.T) {
 			resp.Rcode = dns.RcodeNameError
 		case existingDomain:
 			resp.Rcode = dns.RcodeSuccess
+		case badStatusDomain:
+			w.WriteHeader(400)
+			return
 		default:
 			panic("unexpected question name")
 		}
@@ -61,7 +66,7 @@ func Test_SendViaPost(t *testing.T) {
 		name      string
 		args      args
 		wantRcode int
-		wantErr   bool
+		wantErr   error
 	}{
 		{
 			name:      "NOERROR DNS resolution",
@@ -73,15 +78,20 @@ func Test_SendViaPost(t *testing.T) {
 			args:      args{server: ts.URL, msg: question(notExistingDomain)},
 			wantRcode: dns.RcodeNameError,
 		},
+		{
+			name:    "bad upstream HTTP response",
+			args:    args{server: ts.URL, msg: question(badStatusDomain)},
+			wantErr: &doh.UnexpectedServerHTTPStatusError{},
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			client := NewClient(nil)
+			client := doh.NewClient(nil)
 
 			got, err := client.SendViaPost(context.Background(), tt.args.server, tt.args.msg)
 
-			if tt.wantErr {
-				require.Error(t, err, "SendViaPost() error")
+			if tt.wantErr != nil {
+				require.ErrorAs(t, err, tt.wantErr, "SendViaPost() error")
 			} else {
 				require.NoError(t, err)
 				assert.NotNil(t, got, "SendViaPost() response")
@@ -113,6 +123,9 @@ func Test_SendViaGet(t *testing.T) {
 			resp.Rcode = dns.RcodeNameError
 		case existingDomain:
 			resp.Rcode = dns.RcodeSuccess
+		case badStatusDomain:
+			w.WriteHeader(400)
+			return
 		default:
 			panic("unexpected question name")
 		}
@@ -137,7 +150,7 @@ func Test_SendViaGet(t *testing.T) {
 		name      string
 		args      args
 		wantRcode int
-		wantErr   bool
+		wantErr   error
 	}{
 		{
 			name:      "NOERROR DNS resolution",
@@ -149,15 +162,20 @@ func Test_SendViaGet(t *testing.T) {
 			args:      args{server: ts.URL, msg: question(notExistingDomain)},
 			wantRcode: dns.RcodeNameError,
 		},
+		{
+			name:    "bad upstream HTTP response",
+			args:    args{server: ts.URL, msg: question(badStatusDomain)},
+			wantErr: &doh.UnexpectedServerHTTPStatusError{},
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			client := NewClient(nil)
+			client := doh.NewClient(nil)
 
 			got, err := client.SendViaGet(context.Background(), tt.args.server, tt.args.msg)
 
-			if tt.wantErr {
-				require.Error(t, err, "SendViaGet() error")
+			if tt.wantErr != nil {
+				require.ErrorAs(t, err, tt.wantErr, "SendViaPost() error")
 			} else {
 				require.NoError(t, err)
 				assert.NotNil(t, got, "SendViaGet() response")

doh/errors.go

@@ -0,0 +1,17 @@
+package doh
+
+import "fmt"
+
+// UnexpectedServerHTTPStatusError error indicating that DoH server responded with bad HTTP status code.
+type UnexpectedServerHTTPStatusError struct {
+	code int
+}
+
+func (u UnexpectedServerHTTPStatusError) Error() string {
+	return fmt.Sprintf("unexpected upstream server response HTTP status: %d", u.code)
+}
+
+// HTTPStatus HTTP status code returned by the DoH Server.
+func (u UnexpectedServerHTTPStatusError) HTTPStatus() int {
+	return u.code
+}