I'm trying to develop a simple web server application with Nucleo f411re and w5100 Ethernet shield. My question is why the client.is_fin_received() function always returns 0. Why doesn't my web page complete?

PS : I have no idea about http protocol and html. I think the CR and LF ( '\n' '\r') characters are wrong.

Here is my main.cpp file

#include "mbed.h"
#include "WIZnetInterface.h"

#define USE_W5100
#define ST_NUCLEO
#define MYPORT    80

const char * IP_Addr    = "";
const char * IP_Subnet  = "";
const char * IP_Gateway = "";
unsigned char MAC_Addr[6] = {0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED};

Serial pc(USBTX, USBRX);

SPI spi(PA_7,PA_6,PA_5);
WIZnetInterface ethernet(&spi,PB_6,PA_10);

char page[]={"\r\nHTTP/1.0 200 OK\r\nContent-Type: text/html\r\n\r\n<html><body><h1>PAGE</h1></body></html>\r\n\r\n"};

int i=0;

int main() {

char buffer[300];

int ret = ethernet.init(MAC_Addr,IP_Addr,IP_Subnet,IP_Gateway);

if (!ret) {
    pc.printf("Initialized, MAC: %s\r\n", ethernet.getMACAddress());
    ret = ethernet.connect();
    if (!ret) {
        pc.printf("IP: %s, MASK: %s, GW: %s\r\n",
                  ethernet.getIPAddress(), ethernet.getNetworkMask(), ethernet.getGateway());
    } else {
        pc.printf("Error ethernet.connect() - ret = %d\r\n", ret);
} else {
    pc.printf("Error ethernet.init() - ret = %d\r\n", ret);

TCPSocketServer server;

while (1) {
    pc.printf("\nWait for new connection...\r\n");
    TCPSocketConnection client;
    client.set_blocking(false, 0); // Timeout=0.
    pc.printf("Connection from: %s\r\n", client.get_address());
    while (client.is_connected() == true) {
        int n = client.receive(buffer, sizeof(buffer));



        n = client.receive(buffer, sizeof(buffer));
        for(i=0; i<sizeof(buffer); i++)
            if(buffer[i]==' ')

        pc.printf("\nclient is fin received : %d\r\n",client.is_fin_received());

Result: ScreenShot


I'm not familiar with that platform but two possibilities I can see are:

  • I don't think you need the extra CR/LF at the start of your response (but probably not the main issue).

  • You're not including Content-Length in the header so I think the client will be waiting for the socket to be closed at your end which is why is_fin_received() never returns true.

So I'd try including the Content-Length header which is the length of the of the main body. I'm fairly sure it needs to be the length including the CR/LF characters but you should get an HTTP error response if it's wrong and can adjust.

| improve this answer | |
  • \$\begingroup\$ I edited page[] array as char page[]={"\r\nHTTP/1.0 200 OK\r\nContent-Type: text/html\r\nContent-Length: 39\r\n\r\n<html><body><h1>PAGE</h1></body></html>\r\n\r\n"}; and problem solved .I really appreciate your help thank you so much. \$\endgroup\$ – Fuzzy_Mind Nov 21 '15 at 7:30

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