[lwip-users] udp checksum error

[Muhamad Ikhwan Ismail]

Hi..

As always I have checked any thread having something to do with this, and the only one I found was related to old lwip 0.5 while
I am using lwip 1.2 and things are running very2 well accept for this slight weird problem. I am using the socket API sending some dummy
packets to a UDP echo server I setup on the other node. The sending went well except for I am having UDP checksum error. This didnt happen for TCP.
I used DHCP, which uses UDP directly, and DHCP works fine. So it kinda awkard to me that my short client having this problem.
Any ideas would be welcomed. Following is a piece of the client code. My platform is MPC852T running SMX RTOS.
I also attached the wireshark trace. Thanks a lot in advance.

void test_udp_socket(void){
    int socket_index;
   
    SCB_PTR suspend_udp;    //semaphore used to suspend the thread
    suspend_udp = create_sema(1);
   
    socket_index = lwip_socket(AF_INET,SOCK_DGRAM,0x00);
   
    /*now get a sockaddr structure corresponding to socket domain AF_INET */
    struct sockaddr_in* endpoint = (struct sockaddr_in*)mallocx(sizeof(struct sockaddr));   
    (endpoint)->sin_family = AF_INET;
    (endpoint)->sin_port = (htons(7));
    struct ip_addr server_ip;
    IP4_ADDR(&server_ip,169,254,36,145);
    (endpoint)->sin_addr.s_addr = server_ip.addr;
    int addrlen = (endpoint)->sin_len = sizeof((endpoint)->sin_addr.s_addr);
   
    char* dummy_data = (char*)mallocx(12);
    for(int i =0 ; i<12;i++)
        dummy_data[i]= '2';
   
    while(1){
        lwip_sendto(socket_index,(void*)dummy_data,12,0,(struct sockaddr*)endpoint,addrlen);
        WaitForSingleObject(suspend_udp,SMX_MSEC_TO_TICKS(10));
    }
}

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udp_checksum error.pcap
Description: Binary data