ESP32 Forum

Posted: **Thu Aug 05, 2021 10:41 pm**

Hi,
I am using lwip/sockets.h library to create a TCP Server
to handle just one TCP client connection.
In listen() function I set the amount of TCP clients in queue to
to 0.
But, when I initiate the TCP Server, and try to connect with two TCP clients
at the same time with hercules TCP Client, I get both of them connected to my
TCP Server.

How can I handle this event to just get one of them connected?

I am using an freeRTOS task to set up my TCP server, and then
in the while loop, i used the blocking function: accept().
The while loop doesnt have a delay to execute, but even with a delay
it doesnt work the way I want.

Thank you for your time.

Posted: **Fri Aug 06, 2021 2:02 am**

Your capslock seems to have been accidentally stuck on while typing the title of this topic. I took the liberty to correct that for you. Also, can you post your code somewhere? Your description isn't super clear.

Posted: **Fri Aug 06, 2021 2:11 pm**

Code: [Select all] [Expand/Collapse]

    err = listen(listen_sock, 1); // listen() function 
    if (err != 0) {
        ESP_LOGE(TAG, "Error occurred during listen: errno %d", errno);
        goto CLEAN_UP;
    }
 
    while (1) { // while of freeRTOS task without delay
        struct sockaddr_storage source_addr; // Large enough for both IPv4 or IPv6
        uint addr_len = sizeof(source_addr);
        int sock = accept(listen_sock, (struct sockaddr *)&source_addr, &addr_len);
        if (sock < 0) {
            ESP_LOGE(TAG, "Unable to accept connection: errno %d", errno);
            break;
        }
 
        // Convert ip address to string
        if (source_addr.ss_family == PF_INET) {
            inet_ntoa_r(((struct sockaddr_in *)&source_addr)->sin_addr, addr_str, sizeof(addr_str) - 1);
        } else if (source_addr.ss_family == PF_INET6) {
            inet6_ntoa_r(((struct sockaddr_in6 *)&source_addr)->sin6_addr, addr_str, sizeof(addr_str) - 1);
        }
        ESP_LOGI(TAG, "Socket accepted ip address: %s", addr_str);
        do_retransmit(sock);
        
        shutdown(sock, 0);
        close(sock);
    }
 
CLEAN_UP:
    close(listen_sock);
    vTaskDelete(NULL);
}

Here is the code, thanks for your correction.

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