golangci: enable bodyclose checker and fix related code

It has found an issue in the oracle code, so I think it's worth doing.

.golangci.yml

@@ -42,6 +42,7 @@ linters:
 
     # extra linters
     # - exhaustive
+    - bodyclose
     - gofmt
     - whitespace
     - goimports

pkg/rpcclient/wsclient.go

@@ -90,7 +90,10 @@ var errConnClosedByUser = errors.New("connection closed by user")
 // operating on.
 func NewWS(ctx context.Context, endpoint string, opts Options) (*WSClient, error) {
 	dialer := websocket.Dialer{HandshakeTimeout: opts.DialTimeout}
-	ws, _, err := dialer.Dial(endpoint, nil)
+	ws, resp, err := dialer.Dial(endpoint, nil)
+	if resp != nil && resp.Body != nil { // Can be non-nil even with error returned.
+		defer resp.Body.Close() // Not exactly required by websocket, but let's do this for bodyclose checker.
+	}
 	if err != nil {
 		return nil, err
 	}

pkg/services/oracle/network_test.go

@@ -40,7 +40,7 @@ func TestDefaultClient_RestrictedRedirectErr(t *testing.T) {
 	}
 	for _, c := range testCases {
 		t.Run(c, func(t *testing.T) {
-			_, err := cl.Get(c)
+			_, err := cl.Get(c) //nolint:bodyclose // It errors out and it's a test.
 			require.Error(t, err)
 			require.True(t, errors.Is(err, ErrRestrictedRedirect), err)
 			require.True(t, strings.Contains(err.Error(), "IP is not global unicast"), err)

pkg/services/oracle/request.go

@@ -138,6 +138,7 @@ func (o *Oracle) processRequest(priv *keys.PrivateKey, req request) error {
 				o.Log.Warn("oracle request failed", zap.String("url", req.Req.URL), zap.Error(err), zap.Stringer("code", resp.Code))
 				break
 			}
+			defer r.Body.Close()
 			switch r.StatusCode {
 			case http.StatusOK:
 				if !checkMediaType(r.Header.Get("Content-Type"), o.MainCfg.AllowedContentTypes) {

pkg/services/oracle/response.go

@@ -67,8 +67,6 @@ func (o *Oracle) AddResponse(pub *keys.PublicKey, reqID uint64, txSig []byte) {
 var ErrResponseTooLarge = errors.New("too big response")
 
 func readResponse(rc gio.ReadCloser, limit int) ([]byte, error) {
-	defer rc.Close()
-
 	buf := make([]byte, limit+1)
 	n, err := gio.ReadFull(rc, buf)
 	if err == gio.ErrUnexpectedEOF && n <= limit {

pkg/services/rpcsrv/server_test.go

@@ -2633,8 +2633,9 @@ func checkErrGetBatchResult(t *testing.T, body []byte, expectingFail bool) json.
 func doRPCCallOverWS(rpcCall string, url string, t *testing.T) []byte {
 	dialer := websocket.Dialer{HandshakeTimeout: time.Second}
 	url = "ws" + strings.TrimPrefix(url, "http")
-	c, _, err := dialer.Dial(url+"/ws", nil)
+	c, r, err := dialer.Dial(url+"/ws", nil)
 	require.NoError(t, err)
+	defer r.Body.Close()
 	err = c.SetWriteDeadline(time.Now().Add(time.Second))
 	require.NoError(t, err)
 	require.NoError(t, c.WriteMessage(1, []byte(rpcCall)))
@@ -2651,6 +2652,7 @@ func doRPCCallOverHTTP(rpcCall string, url string, t *testing.T) []byte {
 	resp, err := cl.Post(url, "application/json", strings.NewReader(rpcCall))
 	require.NoErrorf(t, err, "could not make a POST request")
 	body, err := gio.ReadAll(resp.Body)
+	resp.Body.Close()
 	assert.NoErrorf(t, err, "could not read response from the request: %s", rpcCall)
 	return bytes.TrimSpace(body)
 }

pkg/services/rpcsrv/subscription_test.go

@@ -59,8 +59,9 @@ func initCleanServerAndWSClient(t *testing.T) (*core.Blockchain, *Server, *webso
 
 	dialer := websocket.Dialer{HandshakeTimeout: time.Second}
 	url := "ws" + strings.TrimPrefix(httpSrv.URL, "http") + "/ws"
-	ws, _, err := dialer.Dial(url, nil)
+	ws, r, err := dialer.Dial(url, nil)
 	require.NoError(t, err)
+	defer r.Body.Close()
 
 	// Use buffered channel to read server's messages and then read expected
 	// responses from it.
@@ -520,7 +521,10 @@ func TestWSClientsLimit(t *testing.T) {
 	wss := make([]*websocket.Conn, maxSubscribers)
 
 	for i := 0; i < len(wss)+1; i++ {
-		ws, _, err := dialer.Dial(url, nil)
+		ws, r, err := dialer.Dial(url, nil)
+		if r != nil && r.Body != nil {
+			defer r.Body.Close()
+		}
 		if i < maxSubscribers {
 			require.NoError(t, err)
 			wss[i] = ws