Curl

You can implement URL-related transfer activities in Tizen without a Web browser using the open source libcurl library, version 7.40. libcurl is a client-side URL transfer library that supports, among other protocols, HTTP, HTTPS, FTP, and file URIs.

The main features of the Curl API include:

  • Initializing the HTTP and HTTPS request connection

    To allow the application to handle HTTP and HTTPS requests with various options, you must initialize the libcurl library and the connection.

    Note
    In some cases, such as with Internet access, your application requires some privileges. For more information on which privileges to set in the application manifest file, see Non-API Bound Privileges.

  • Managing the proxy address

    You can get and set the proxy address in multiple ways.

    Note
    In a proxy environment, the libcurl library does not know the proxy address. To handle HTTP and HTTPS requests in a proxy environment, first get the proxy address using the connection manager, and then set the proxy address using the Curl API.

  • Transferring HTTP requests

    You can transfer HTTP requests using the curl_easy_setopt() function.

Prerequisites

To enable your application to use the Curl functionality:

  1. To use the Curl API (in mobile and wearable applications) and the libcurl library, the application has to request permission by adding the following privilege to the tizen-manifest.xml file:

    <privileges>
   <privilege>http://tizen.org/privilege/internet</privilege>
</privileges>

  2. To use the functions and data types of the Curl API, include the <curl.h> header file in your application. You must also add the <net_connection.h> header file to get the proxy address.

    #include <curl.h>
#include <net_connection.h>

  3. Initialize the Curl library and the Curl handle using the curl_easy_init() function:

    CURL *curl;
CURLcode curl_err;
curl = curl_easy_init();

  4. Create and initialize a connection handle by calling the connection_create() function:

    connection_h connection;
int conn_err;
conn_err = connection_create(&connection);
if (conn_err != CONNECTION_ERROR_NONE) {
    /* Error handling */

    return;
}

  5. When no longer needed, clear the Curl and connection handle to finish the HTTP transaction:

    curl_easy_cleanup(curl);
connection_unset_proxy_address_changed_cb(connection);
connection_destroy(connection);

Managing the Proxy Address

There are 2 ways for getting and setting the proxy address:

  • To get the proxy address directly, use the connection_get_proxy() function of the Connection Manager API (in mobile and wearable applications):
    char *proxy_address;
conn_err = connection_get_proxy(connection, CONNECTION_ADDRESS_FAMILY_IPV4, &proxy_address);
    To set the proxy address, use the curl_easy_setopt() function with the CURLOPT_PROXY parameter:
    if (conn_err == CONNECTION_ERROR_NONE && proxy_address)
    curl_easy_setopt(curl, CURLOPT_PROXY, proxy_address);
  • To be notified whenever the proxy address changes, register a callback with the connection_set_proxy_address_changed_cb() function of the Connection Manager API:
    conn_err = connection_set_proxy_address_changed_cb(connection,
                                                   __proxy_address_changed_cb, NULL);
if (conn_err != CONNECTION_ERROR_NONE) {
    /* Error handling */

    return;
}
    The new proxy address is passed in the callback parameters. To set the proxy address, use the curl_easy_setopt() function with the CURLOPT_PROXY parameter:
    static void
__proxy_address_changed_cb(const char *ipv4_address,
                           const char *ipv6_address, void *user_data)
{
    curl_easy_setopt(curl, CURLOPT_PROXY, ipv4_address);
}

Transferring HTTP Requests

To transfer HTTP requests, set the URL with the curl_easy_setopt() function and start the transfer with the curl_easy_perform() function:

curl_easy_setopt(curl, CURLOPT_URL, "https://www.tizen.org/");
curl_err = curl_easy_perform(curl);
if (curl_err != CURLE_OK)
    /* Error handling */
  • Dependencies
    • Tizen 2.4 and Higher for Mobile
    • Tizen 2.3.1 and Higher for Wearable
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