Add WiFiClient flush to clear all non-read data in RX

fixes: espressif#119

Author: me-no-dev

libraries/WiFi/src/WiFiClient.cpp

@@ -24,6 +24,7 @@
 
 #define WIFI_CLIENT_MAX_WRITE_RETRY (10)
 #define WIFI_CLIENT_SELECT_TIMEOUT_US (100000)
+#define WIFI_CLIENT_FLUSH_BUFFER_SIZE (1024)
 
 #undef connect
 #undef write
@@ -251,6 +252,32 @@ int WiFiClient::available()
  return count;
 }
 
+// Though flushing means to send all pending data,
+// seems that in Arduino it also means to clear RX
+void WiFiClient::flush() {
+ size_t a = available(), toRead = 0;
+ if(!a){
+ return;//nothing to flush
+ }
+ uint8_t * buf = (uint8_t *)malloc(WIFI_CLIENT_FLUSH_BUFFER_SIZE);
+ if(!buf){
+ return;//memory error
+ }
+ while(a){
+ toRead = (a>WIFI_CLIENT_FLUSH_BUFFER_SIZE)?WIFI_CLIENT_FLUSH_BUFFER_SIZE:a;
+ if(recv(fd(), buf, toRead, MSG_DONTWAIT) < 0) {
+ if(errno != EWOULDBLOCK){
+ log_e("%d", errno);
+ stop();
+ break;
+ }
+ delay(1);//give some time
+ }
+ a = available();
+ }
+ free(buf);
+}
+
 uint8_t WiFiClient::connected()
 {
  uint8_t dummy = 0;

libraries/WiFi/src/WiFiClient.h

@@ -49,7 +49,7 @@ class WiFiClient : public Client
  {
  return 0;
  }
- void flush() {}
+ void flush();
  void stop();
  uint8_t connected();