[lwip-users] tcp_write fails: package generation doesn't work properly

[Friedrico]

Hello,

I have the following setup:
Server (Lwip 1.4.1 in a VM)
Client (also 1.4.1 on an Infineon Triboard using Erika Enterprise os)

The client code looks similar to this:
> struct tcp_pcb *tcpPcb;
> static const char data[] = "..." /*100 bytes*/
>
> static err_t tcpReceive(void *arg, struct tcp_pcb *pcb, struct pbuf *p,
>         err_t err) {
>     return ERR_OK;
> }
> static err_t tcpSent(void *arg, struct tcp_pcb *tpcb, u16_t len) {
>     return ERR_OK;
> }
>
>
> void initTcp(){
>     data=/*...*/
>     ip_addr_t *target, *local;
>     tcpPcb = tcp_new();
>     tcp_sent(tcpPcb, tcpSent);
>     tcp_recv(tcpPcb, tcpReceive);
>     tcp_arg(tcpPcb, data);
>     tcp_nagle_disable(tcpPcb);
>     tcp_bind(tcpPcb, local, C_PORT);
>     tcp_connect(tcpPcb, target, S_PORT, NULL);
> }
>
> void sendData(void *data) {
>     tcp_write(tcpPcb, data, 100, 0);
> }



The server code uses the socket api:
> struct sockaddr_in client_addr;
> int addrlen=sizeof(client_addr);
> int lSocket,nbytes,clientfd;
>
> lSocket = socket(PF_INET, SOCK_STREAM, 0);
> memset(&sa, 0, sizeof(struct sockaddr_in));
> sa.sin_family = AF_INET;
> sa.sin_addr.s_addr = INADDR_ANY;
> sa.sin_port = htons(PORT);
>
> bind(lSocket, (struct sockaddr *)&sa, sizeof(sa))
> listen(lSocket,5);
> addr_size = sizeof(isa);
> while(1){
>     clientfd = accept(lSocket, (struct sockaddr*)&client_addr,
>     (socklen_t)&addrlen);
>     while (1){
>         nbytes=recv(clientfd, data, datalen,0);
>         if (nbytes>0){
>             send(clientfd, data, datalen, 0);
>         }
>     }
>     close(clientfd);
> }
> close(lSocket); 

lwipopts.h (client):
> #define MEMP_NUM_TCP_PCB        13
> #define MEMP_NUM_TCP_PCB_LISTEN 6
> #define MEMP_NUM_TCP_SEG      200
> #define MEMP_NUM_SYS_TIMEOUT    6
> #define PBUF_POOL_SIZE          11
> #define PBUF_POOL_BUFSIZE       1536
> #define LWIP_TCP                1
> #define TCP_TTL                 255
> #define TCPIP_THREAD_STACKSIZE                  LWIP_STK_SIZE
> #define TCP_QUEUE_OOSEQ         0
> #define TCPIP_MBOX_SIZE         MAX_QUEUE_ENTRIES //==20
> #define DEFAULT_TCP_RECVMBOX_SIZE       MAX_QUEUE_ENTRIES
> #define DEFAULT_ACCEPTMBOX_SIZE         MAX_QUEUE_ENTRIES
> #define TCP_MSS                 (1500 - 40)      /* TCP_MSS = 
> (Ethernet MTU - IP header size - TCP header size) */
> #define TCP_SND_BUF             (4*TCP_MSS)
> #define TCP_SND_QUEUELEN        (6 * TCP_SND_BUF)/TCP_MSS
> #define TCP_WND                 (2*TCP_MSS)


I attached the pcapng wireshark gathered.
No 12. shows the transmission of a test packet from server to client 
which works as intended.
No 16. should show the transmission back to the server which fails as 
one can see.
Even the payload is wrong (6 times 0) - it should be 100 bytes in length 
and contain the teststring, shouldn't it?

Can someone tell me where to search for the problem's cause?

Regards,
Friedrico

board.pcapng
Description: Binary data