Handling of unexpectedly terminated sessions (#9)

client.go

@@ -240,6 +240,20 @@ func (client *Client) Do(req Req) (Res, error) {
 			} else if httpRes.StatusCode == 429 || (httpRes.StatusCode >= 500 && httpRes.StatusCode <= 599) {
 				log.Printf("[ERROR] HTTP Request failed: StatusCode %v, Retries: %v", httpRes.StatusCode, attempts)
 				continue
+			} else if httpRes.StatusCode == 401 {
+				// There are bugs in FMC, where the sessions are invalidated out of the blue
+				// In case such a situation is detected, new authentication is forced
+				log.Printf("[DEBUG] Invalid session detected. Forcing reauthentication")
+				// Clear AuthToken (which is invalid anyways). This also ensures that Authenticate does full authentication
+				client.AuthToken = ""
+				// Force reauthentication, client.Authenticate() takes care of mutexes, hence not calling Login() directly
+				err := client.Authenticate()
+				if err != nil {
+					log.Printf("[DEBUG] HTTP Request failed: StatusCode 401: Forced reauthentication failed: %s", err.Error())
+					return res, fmt.Errorf("HTTP Request failed: StatusCode 401: Forced reauthentication failed: %s", err.Error())
+				}
+				req.HttpReq.Header.Set("X-auth-access-token", client.AuthToken)
+				continue
 			} else {
 				log.Printf("[ERROR] HTTP Request failed: StatusCode %v", httpRes.StatusCode)
 				log.Printf("[DEBUG] Exit from Do method")