19. Http client

19.1. Overview

This example explains the process of how to create a socket and connect to access the specified Http server to obtain data.

19.2. Preparation and Usage Steps

• Prepare a usable URL and network.

• Steps to use:

  • Compile and flash customer_app/sdk_app_http_client_socket.

  • Enter the command stack_wifi to turn on wifi in the terminal, then enter the command wifi_sta_connect <name> <key> to connect to wifi. Confirm that the wifi connection is successful (e.g. use the command wifi_sta_connect bl_test_005 12345678).

    

    

  • Use http command to download through socket.

    

19.3. Applications

• Obtain hostinfo by hostname.

struct hostent *hostinfo = gethostbyname(hostname);
if (!hostinfo) {
    printf("gethostbyname Failed\r\n");
    return -1;
}

• Create a socket connection and send the http request.

if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
    printf("Error in socket\r\n");
    return -1;
}
/*---Initialize server address/port struct---*/
memset(&dest, 0, sizeof(dest));
dest.sin_family = AF_INET;
dest.sin_port = htons(PORT);
dest.sin_addr = *((struct in_addr *) hostinfo->h_addr);
//char ip[16];
uint32_t address = dest.sin_addr.s_addr;
char *ip = inet_ntoa(address);

printf("Server ip Address : %s\r\n", ip);
/*---Connect to server---*/
if (connect(sockfd,
         (struct sockaddr *)&dest,
         sizeof(dest)) != 0) {
    printf("Error in connect\r\n");
    return -1;
}
/*---Get "Hello?"---*/
memset(buffer, 0, MAXBUF);
char wbuf[]
    = "GET /ddm/ContentResource/music/204.mp3 HTTP/1.1\r\nHost: nf.cr.dandanman.com\r\nUser-Agent: wmsdk\r\nAccept: */*\r\n\r\n";
write(sockfd, wbuf, sizeof(wbuf) - 1);

• Recieve http response data. Print the time of cost to recieve data and the speed of transfer when complete.

while (1) {
    ret = read(sockfd, recv_buffer, BUFFER_SIZE);
    if (ret == 0) {
        printf("eof\n\r");
        break;
    } else if (ret < 0) {
        printf("ret = %d, err = %d\n\r", ret, errno);
        break;
    } else {
        total += ret;
        /*use less debug*/
        if (0 == ((debug_counter++) & 0xFF)) {
            printf("total = %d, ret = %d\n\r", total, ret);
        }
        //vTaskDelay(2);
        if (total > 82050000) {
            ticks_end = xTaskGetTickCount();
            time_consumed = ((uint32_t)(((int32_t)ticks_end) - ((int32_t)ticks_start))) / 1000;
            printf("Download comlete, total time %u s, speed %u Kbps\r\n",
                    (unsigned int)time_consumed,
                    (unsigned int)(total / time_consumed * 8 / 1000)
            );
            break;
        }
    }

• Close socket.

close(sockfd);

• In customer_app/sdk_app_http_client_socket/sdk_app_http_client_socket/demo.c, the function static void _cli_init() would call http_client_cli_init() to initialize http.