Send UDP packet using Arduino problem

Projects Networking, Protocols, and Devices
1

Hello everyone ,

I have a problem in my UDP packet sender i will describe it. first this is the code

#include <ESP8266WiFi.h>
#include <WiFiUdp.h>
   
// Set WiFi credentials
#define WIFI_SSID "DIGI_676df8"
#define WIFI_PASS "aa219892"
#define UDP_PORT 9180

 // UDP
WiFiUDP UDP;
char packet[255];
char reply[] = "Packet received!";
char packet_ret[36] = {01,0x24,00,0x1E,06,00,00,00,0x0B,00,00,00,0x10,00,00,00,0x15,00,00,00,0x1A,00,00,00,0x1F,00,00,00,0x24,00,00,00,0x29,00,00,00} ;

 
void setup() {

  Serial.begin(115200);
  Serial.println();
   

  WiFi.begin(WIFI_SSID , WIFI_PASS);
   

  Serial.print("Connecting to ");
  Serial.print(WIFI_SSID );
  Serial.print(WIFI_PASS);

  while (WiFi.status() != WL_CONNECTED)
  {
    delay(100);
    Serial.print(".");
  }
   

  Serial.println();
  Serial.print("Connected! IP address: ");
  Serial.println(WiFi.localIP());


  UDP.begin(UDP_PORT);
  Serial.print("Listening on UDP port ");
  Serial.println(UDP_PORT);
   
}
   
void loop() {
 
int packetSize = UDP.parsePacket();
  if (packetSize) {
    Serial.print("Received packet! Size: ");
    Serial.println(packetSize); 
    int len = UDP.read(packet, 255);
   if (len > 0)
    {
      packet[len] = '\0';
    }

    UDP.beginPacket(UDP.remoteIP(), UDP.remotePort());
    UDP.write(reply);
    UDP.endPacket();

    UDP.beginPacket(UDP.remoteIP(), UDP.remotePort());
    UDP.write(packet_ret);
    UDP.endPacket();

  }
 
 
}

I'm using Wireshark to monitor the packets , for the 1st reply array it worked perfectly and i can see it in the program
280211 22240.862216 192.168.1.6 192.168.1.2 UDP 58 9180 → 9180 Len=16
the sent data : Packet received!
while for the 2nd reply packet_ret it should be a36 bytes message, but in wireshark i could see that the arduino only sent 2 bytes as following
280212 22240.862610 192.168.1.6 192.168.1.2 UDP 44 9180 → 9180 Len=2
the sent data: only 0124

both arrays type is char, so i couldn't really know why this happen.

2

Try explicitly stating the packet size.

    UDP.write(packet_ret, 36);

I suspect it is currently terminating when if finds 0x00.

4

@

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