how to use cURL with TLS implementation

[s-shige]

Hello

I'm evaluating cURL with nrf9160DK,zephyrOS.

Finally, it goes well with cURL - http - however, it cant do with TLS - https -

Could you let me know how to implement TLS/SSL for using cURL ?

Does it require some config ?

Here is my snipet code. (non - TLS)

-------------------------------------------------------------

static size_t write_callback(void *contents, size_t size, size_t nmemb, void *userp) {
size_t realsize = size * nmemb;
char **response_ptr = (char **)userp; // Cast userp to the correct type
char *response = realloc(*response_ptr, strlen(*response_ptr) + realsize + 1);

if (response == NULL) {
LOG_ERR("Not enough memory to store response\n");
return 0; // If realloc fails, return 0 to stop curl
}

*response_ptr = response;
strncat(response, (char *)contents, realsize);

return realsize;
}

static void http_request_example(void) {
CURL *hnd;
CURLcode ret;
char *response = malloc(4096); // Allocate initial memory for the response
if (response == NULL) {
LOG_ERR("Memory allocation failed for response buffer");
return;
}
response[0] = '\0'; // Initialize the response buffer

LOG_INF("Starting HTTP request example");

// Initialize libcurl
hnd = curl_easy_init();
if (hnd) {
// Set the URL for the HTTP GET request
curl_easy_setopt(hnd, CURLOPT_URL, "">http://httpbin.org/get");

// Set the callback function for handling response data
curl_easy_setopt(hnd, CURLOPT_WRITEFUNCTION, write_callback);
curl_easy_setopt(hnd, CURLOPT_WRITEDATA, (void *)&response);

#if 1
curl_version_info_data *curl_info = curl_version_info(CURLVERSION_NOW);
if (curl_info->protocols) {
const char * const *proto;
for (proto = curl_info->protocols; *proto; ++proto) {
LOG_INF("Supported protocol: %s\n", *proto);
}
}
#endif

// Perform the request
ret = curl_easy_perform(hnd);

// Check if the request was successful
if (ret != CURLE_OK) {
LOG_ERR("curl_easy_perform() failed: %s", curl_easy_strerror(ret));
} else {
// Print the response
LOG_INF("Response: %s", response);
}

// Clean up and free the resources
curl_easy_cleanup(hnd);
free(response);
} else {
LOG_ERR("Failed to initialize curl");
}
}

[s-shige]

Updated my code and however, still no work well.

>>curl_version_info(CURLVERSION_NOW);

Return - http

>>curl_easy_perform() failed: Unsupported protocol

how to integrated SSL/TLS ?

here is the snipet code

-----------------------------------------------------------------------

static void https_request_example(void) {
CURL *ch;
CURLcode ret;

char *response = malloc(4096); // Allocate initial memory for the response
if (response == NULL) {
LOG_ERR("Memory allocation failed for response buffer");
return;
}
response[0] = '\0'; // Initialize the response buffer

LOG_INF("Starting HTTPS request example");

/* Dynamically allocate memory for the PEM certificate */
char *mypem = (char *)malloc(strlen(cert_pem) + 1);
if (!mypem) {
printf("malloc failed for PEM certificate\n");
return CURLE_OUT_OF_MEMORY;
}
strcpy(mypem, cert_pem);

curl_global_init(CURL_GLOBAL_ALL);
ch = curl_easy_init();
if (ch) {

curl_easy_setopt(ch, CURLOPT_SSLCERTTYPE, "PEM");
curl_easy_setopt(ch, CURLOPT_SSL_VERIFYPEER, 1L);
curl_easy_setopt(ch, CURLOPT_URL, "">https://www.example.com/");

/* Install the function to modify the SSL context */
curl_easy_setopt(ch, CURLOPT_SSL_CTX_FUNCTION, *sslctx_function);
curl_easy_setopt(ch, CURLOPT_SSL_CTX_DATA, mypem);

// Set the callback function for handling response data
curl_easy_setopt(ch, CURLOPT_WRITEFUNCTION, write_callback);
curl_easy_setopt(ch, CURLOPT_WRITEDATA, (void *)&response);

#if 1
curl_version_info_data *curl_info = curl_version_info(CURLVERSION_NOW);
if (curl_info->protocols) {
const char * const *proto;
for (proto = curl_info->protocols; *proto; ++proto) {
LOG_INF("Supported protocol: %s\n", *proto);
}
}
#endif

// Perform the request
ret = curl_easy_perform(ch);

// Check if the request was successful
if (ret != CURLE_OK) {
LOG_ERR("curl_easy_perform() failed: %s", curl_easy_strerror(ret));
} else {
// Print the response
LOG_INF("Response: %s", response);
}

// Clean up and free the resources
curl_easy_cleanup(ch);
free(response);

} else {
LOG_ERR("Failed to initialize curl");
}

/* Clean up */
curl_easy_cleanup(ch);
curl_global_cleanup();
free(mypem); /* Free dynamically allocated memory */
free(response);

return ret;
}

[s-shige]

Hello

Still not going well and I'm looking for solution.

Any idea and advice would be highly appreciated.

thx

[Øyvind]

Hello, 

Michal is currently out of office and I have been assigned his ticket while he is out. 

s-shige said:

That means this is not support ?

Yes, there is currently no support for cURL and HTTPS in our nRF Connect SDK. The cURL library in our SDK was introduced for our Cellular: Modem shell sample.

Kind regards,
Øyvind

[s-shige]

Hello

Thank you for your update.

I can confirm cURL (without TLS) is available.

but, need "CONFIG_NET_SOCKETS_POSIX_NAMES=n" so, some hand craft to implement socket function with zepher API.

Anyway, TLS(mbedTLS) is not supported for now, I understand.

We have often request about this feature support from customers.

so, I hope it will support shortly.

thx

[Øyvind]

If you are able to provide a list of how many that asks about this, we can forward this as a feature request. 

Kind regards,
Øyvind

[s-shige]

Hello

We have a few customers that using Nordic.

That kind point of view regarding your chip product will be some volume of K, M numbers. 

thx

[Øyvind]

Okay, thanks!