[#15] Fix redirects

Signed-off-by: Denis Kirillov <denis@nspcc.ru>

plugin/geodns/geodns_test.go

@@ -20,11 +20,18 @@ func TestFiltering(t *testing.T) {
 	ctx := context.Background()
 
 	// to test healthchecker
-	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
-		w.WriteHeader(http.StatusOK)
-	})
 	go func() {
-		err := http.ListenAndServe("0.0.0.0:8080", nil)
+		mux := http.NewServeMux()
+		mux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
+			w.WriteHeader(http.StatusOK)
+		})
+
+		srv := http.Server{
+			Addr:    "0.0.0.0:8080",
+			Handler: mux,
+		}
+
+		err := srv.ListenAndServe()
 		require.NoError(t, err)
 	}()
 
@@ -80,7 +87,7 @@ func TestFiltering(t *testing.T) {
 				"test.neofs": tc.records,
 			})
 			geoDNS.filter.health.schema = "http://"
-			geoDNS.filter.health.port = ":8080"
+			geoDNS.filter.health.port = "8080"
 			for _, ip := range []string{Orgrimar, WarsongHold, Stormwind} {
 				_ = geoDNS.filter.health.cache.Set(ip, true)
 			}

plugin/geodns/health.go

@@ -21,6 +21,9 @@ func newHealthChecker() *checker {
 		cache: gcache.New(1000).Expiration(30 * time.Second).Build(),
 		client: &http.Client{
 			Timeout: 2 * time.Second,
+			CheckRedirect: func(*http.Request, []*http.Request) error {
+				return http.ErrUseLastResponse
+			},
 		},
 		schema: "http://",
 		port:   "80",

plugin/geodns/health_test.go

@@ -0,0 +1,36 @@
+package geodns
+
+import (
+	"net/http"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestNoRedirect(t *testing.T) {
+	go func() {
+		mux := http.NewServeMux()
+		mux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
+			http.Redirect(w, r, "/redirected", http.StatusMovedPermanently)
+		})
+		mux.HandleFunc("/redirected", func(w http.ResponseWriter, r *http.Request) {
+			w.WriteHeader(http.StatusInternalServerError)
+		})
+		srv := http.Server{
+			Addr:    "localhost:8888",
+			Handler: mux,
+		}
+		err := srv.ListenAndServe()
+		require.NoError(t, err)
+	}()
+
+	checker := newHealthChecker()
+	checker.port = "8888"
+
+	condition := func() bool {
+		return checker.checkOne("127.0.0.1")
+	}
+
+	require.Eventually(t, condition, 5*time.Second, 500*time.Millisecond)
+}