NRF9160 HTTPS Client Example Modification

[Waqas Qammar]

Hello All,

I am working on NRF9160. I was checking the HTTPS_CLIENT Example. But in my application I wanted to use the link that has header as well. How can I modify the existing example that it work for me. I am struggling to find the resources to learn and currently nrf9160 has a much steeper lurning curve. 

Kindly help me with this and if possible kindly mention some resources as well so I can understand the code better.

This is the command that I use for curl and I wanted to use with NRF9160

curl -X 'GET' \
  'https://api.abc.com/u/123456789/' \
  -H 'accept: application/json' \
  -H 't: PRIVATE_AUTHENTICATION TOKEN'

here is the example code of HTTPS CLIENT

#include <string.h>
#include <zephyr.h>
#include <stdlib.h>
#include <net/socket.h>
#include <modem/nrf_modem_lib.h>
#include <net/tls_credentials.h>
#include <modem/lte_lc.h>
#include <modem/at_cmd.h>
#include <modem/at_notif.h>
#include <modem/modem_key_mgmt.h>

#define HTTPS_PORT 443

#define HTTP_HEAD                                                              \
	"HEAD / HTTP/1.1\r\n"                                                  \
	"Host: www.google.com:443\r\n"                                         \
	"Connection: close\r\n\r\n"

#define HTTP_HEAD_LEN (sizeof(HTTP_HEAD) - 1)

#define HTTP_HDR_END "\r\n\r\n"

#define RECV_BUF_SIZE 2048
#define TLS_SEC_TAG 42

static const char send_buf[] = HTTP_HEAD;
static char recv_buf[RECV_BUF_SIZE];

/* Certificate for `google.com` */
static const char cert[] = {
	#include "../cert/GlobalSign-Root-CA-R2"
};

BUILD_ASSERT(sizeof(cert) < KB(4), "Certificate too large");


/* Initialize AT communications */
int at_comms_init(void)
{
	int err;

	err = at_cmd_init();
	if (err) {
		printk("Failed to initialize AT commands, err %d\n", err);
		return err;
	}

	err = at_notif_init();
	if (err) {
		printk("Failed to initialize AT notifications, err %d\n", err);
		return err;
	}

	return 0;
}

/* Provision certificate to modem */
int cert_provision(void)
{
	int err;
	bool exists;
	uint8_t unused;

	err = modem_key_mgmt_exists(TLS_SEC_TAG,
				    MODEM_KEY_MGMT_CRED_TYPE_CA_CHAIN,
				    &exists, &unused);
	if (err) {
		printk("Failed to check for certificates err %d\n", err);
		return err;
	}

	if (exists) {
		/* For the sake of simplicity we delete what is provisioned
		 * with our security tag and reprovision our certificate.
		 */
		err = modem_key_mgmt_delete(TLS_SEC_TAG,
					    MODEM_KEY_MGMT_CRED_TYPE_CA_CHAIN);
		if (err) {
			printk("Failed to delete existing certificate, err %d\n",
			       err);
		}
	}

	printk("Provisioning certificate\n");

	/*  Provision certificate to the modem */
	err = modem_key_mgmt_write(TLS_SEC_TAG,
				   MODEM_KEY_MGMT_CRED_TYPE_CA_CHAIN,
				   cert, sizeof(cert) - 1);
	if (err) {
		printk("Failed to provision certificate, err %d\n", err);
		return err;
	}

	return 0;
}

/* Setup TLS options on a given socket */
int tls_setup(int fd)
{
	int err;
	int verify;

	/* Security tag that we have provisioned the certificate with */
	const sec_tag_t tls_sec_tag[] = {
		TLS_SEC_TAG,
	};

	/* Set up TLS peer verification */
	enum {
		NONE = 0,
		OPTIONAL = 1,
		REQUIRED = 2,
	};

	verify = REQUIRED;

	err = setsockopt(fd, SOL_TLS, TLS_PEER_VERIFY, &verify, sizeof(verify));
	if (err) {
		printk("Failed to setup peer verification, err %d\n", errno);
		return err;
	}

	/* Associate the socket with the security tag
	 * we have provisioned the certificate with.
	 */
	err = setsockopt(fd, SOL_TLS, TLS_SEC_TAG_LIST, tls_sec_tag,
			 sizeof(tls_sec_tag));
	if (err) {
		printk("Failed to setup TLS sec tag, err %d\n", errno);
		return err;
	}

	return 0;
}

void main(void)
{
	int err;
	int fd;
	char *p;
	int bytes;
	size_t off;
	struct addrinfo *res;
	struct addrinfo hints = {
		.ai_family = AF_INET,
		.ai_socktype = SOCK_STREAM,
	};

	printk("HTTPS client sample started\n\r");

	err = nrf_modem_lib_init(NORMAL_MODE);
	if (err) {
		printk("Failed to initialize modem library!");
		return;
	}

	/* Initialize AT comms in order to provision the certificate */
	err = at_comms_init();
	if (err) {
		return;
	}

	/* Provision certificates before connecting to the LTE network */
	err = cert_provision();
	if (err) {
		return;
	}

	printk("Waiting for network.. ");
	err = lte_lc_init_and_connect();
	if (err) {
		printk("Failed to connect to the LTE network, err %d\n", err);
		return;
	}
	printk("OK\n");

	err = getaddrinfo("google.com", NULL, &hints, &res);
	if (err) {
		printk("getaddrinfo() failed, err %d\n", errno);
		return;
	}

	((struct sockaddr_in *)res->ai_addr)->sin_port = htons(HTTPS_PORT);

	fd = socket(AF_INET, SOCK_STREAM, IPPROTO_TLS_1_2);
	if (fd == -1) {
		printk("Failed to open socket!\n");
		goto clean_up;
	}

	/* Setup TLS socket options */
	err = tls_setup(fd);
	if (err) {
		goto clean_up;
	}

	printk("Connecting to %s\n", "google.com");
	err = connect(fd, res->ai_addr, sizeof(struct sockaddr_in));
	if (err) {
		printk("connect() failed, err: %d\n", errno);
		goto clean_up;
	}

	off = 0;
	do {
		bytes = send(fd, &send_buf[off], HTTP_HEAD_LEN - off, 0);
		if (bytes < 0) {
			printk("send() failed, err %d\n", errno);
			goto clean_up;
		}
		off += bytes;
	} while (off < HTTP_HEAD_LEN);

	printk("Sent %d bytes\n", off);

	off = 0;
	do {
		bytes = recv(fd, &recv_buf[off], RECV_BUF_SIZE - off, 0);
		if (bytes < 0) {
			printk("recv() failed, err %d\n", errno);
			goto clean_up;
		}
		off += bytes;
	} while (bytes != 0 /* peer closed connection */);

	printk("Received %d bytes\n", off);

	/* Print HTTP response */
	p = strstr(recv_buf, "\r\n");
	if (p) {
		off = p - recv_buf;
		recv_buf[off + 1] = '\0';
		printk("\n>\t %s\n\n", recv_buf);
	}

	printk("Finished, closing socket.\n");

clean_up:
	freeaddrinfo(res);
	(void)close(fd);
}

Thanks

[Didrik Rokhaug]

Hi,

You want to modify the HTTP_HEAD macro. The path "/u/123456789" replaces the "/" on the first line, the host "api.abc.com" replaces "www.google.com" on the second line.

The accept and t headers should be added to their own lines, but should be above the "Connection" header (or you need to edit the line ending to only har \r\n, the head ends with \r\n\r\n).

Best regards,

Didrik

[Waqas Qammar]

Hi Didrik,

Thanks for your reply,

also can I use this example without certificate? what should I need to comment out so it can work may be with simple http or without certificate?

Thanks

[Didrik Rokhaug]

Waqas Qammar said:

also can I use this example without certificate? what should I need to comment out so it can work may be with simple http or without certificate?

 Do you want TLS or not?

For TLS, you must have at least a CA certificate provisioned to the modem.

But, if you don't want TLS, you must change the IPPROTO_TLS_1_2 to IPPROTO_TCP, and comment out the calls to cert_provison (not strictly necessary, you will simply not use them) and tls_setup.

[Waqas Qammar]

Hi Didrik,

I was using v1.4.2 and found out the modem library was developed after this version. I have updated the version to 1.5.1 and now when I am compiling I was getting  error

["Key 'module_ext_root' was not defined. Path: '/build/settings'"]

ERROR: Malformed "build" section in file:
D:/work-freelance/JAN/Firmware/ncs/nrf/zephyr/module.yml

<SchemaError: error code 2: Schema validation failed:

- Key 'module_ext_root' was not defined. Path: '/build/settings'.: Path: '/'>

[Didrik Rokhaug]

Did you install NCS manually or through the Toolchain Manager?

If you are using the Toolchain Manager, you should install the correct version of the toolchain, and open the terminal from the Toolchain Manager.

If you installed the toolchain manually, you must ensure that you have the correct version of all the tools yourself.

You can then export a Zephyr CMake package to let your applications find the correct toolchain: https://developer.nordicsemi.com/nRF_Connect_SDK/doc/1.5.1/zephyr/guides/zephyr_cmake_package.html#cmake-pkg