mqtt connect error

[octvargas]

Hello, 

So I'm trying to modify the mqtt_simple sample program to connect to azure iot

I've modified the code in a few ways but when I went to run the program it gave me this error

Which from my understanding is a failure to connect w/ the mqtt client

and the mqtt_connect error comes from the mqtt.h/c file which is an error of  ENOMEM (err no memory??) in the tx_buf or the rx_buf

So I manually changed the buffer size in the config file

Fullscreen configuration.txt Download

# General config
CONFIG_TEST_RANDOM_GENERATOR=y

# Networking
CONFIG_NETWORKING=y
CONFIG_NET_SOCKETS_OFFLOAD=y
CONFIG_NET_SOCKETS=y
CONFIG_NET_SOCKETS_POSIX_NAMES=y

# LTE link control
CONFIG_LTE_LINK_CONTROL=y
CONFIG_LTE_AUTO_INIT_AND_CONNECT=n

# BSD library
CONFIG_BSD_LIBRARY=y

# AT Host
CONFIG_UART_INTERRUPT_DRIVEN=y
CONFIG_AT_HOST_LIBRARY=y

# MQTT
CONFIG_MQTT_LIB=y
CONFIG_MQTT_LIB_TLS=n

# Appliaction
CONFIG_MQTT_PUB_TOPIC="publish"
CONFIG_MQTT_SUB_TOPIC="subscribe"
CONFIG_MQTT_CLIENT_ID="MyCDevice"
CONFIG_MQTT_BROKER_HOSTNAME="MaxusHub.azure-devices.net"
CONFIG_MQTT_BROKER_PORT=11105

# Main thread
CONFIG_MAIN_THREAD_PRIORITY=7
CONFIG_MAIN_STACK_SIZE=4096

CONFIG_HEAP_MEM_POOL_SIZE=1024

# Disable native network stack to save some memory
CONFIG_NET_IPV4=n
CONFIG_NET_IPV6=n
CONFIG_NET_UDP=n
CONFIG_NET_TCP=n

#added Configuring of buffer sizes?
CONFIG_MQTT_MESSAGE_BUFFER_SIZE = 128
CONFIG_MQTT_PAYLOAD_BUFFER_SIZE = 128

And once I try to build it, it gives me an out of tree board error

My main question is, would I be able to resolve the -12 mqtt_connect error by adjusting the buffer size? And if so, how would I go about doing that if not in the proj.conf file.

Any help is appreciated, thank you

Octavio

EDIT: I should add, I tried running SES as administrator and that didn't seem to help.

[Sigurd]

Hi,

There is some syntax error in your config file, you should remove the space around the = sign, i.e. so it looks like this instead:

CONFIG_MQTT_MESSAGE_BUFFER_SIZE=128
CONFIG_MQTT_PAYLOAD_BUFFER_SIZE=128

octvargas said:

would I be able to resolve the -12 mqtt_connect error by adjusting the buffer size?

It's worth trying, but if you are hitting the ENOMEM shown in the screenshot you attached, then it seems like you are getting the ENOMEM because the buffers are NULL.

Did you call client_init() before calling mqtt_connect() ?

	client_init(&client);
	err = mqtt_connect(&client);

And are the buffers defined like this ?

/* Buffers for MQTT client. */
static u8_t rx_buffer[CONFIG_MQTT_MESSAGE_BUFFER_SIZE];
static u8_t tx_buffer[CONFIG_MQTT_MESSAGE_BUFFER_SIZE];
static u8_t payload_buf[CONFIG_MQTT_PAYLOAD_BUFFER_SIZE];

[octvargas]

Hi Sigurd, 

Okay, so I've got my current problems narrowed down to the poll function in main.

When it returns my fds.revents has a value of 0x10 which apparently means that the poll detected a closed connection?

How would I go about enabling the socket for readability, or I guess how would I proceed from here?

Thank you

[octvargas]

That was gonna be my next question, how would I go about using my certificates? I've been reading through the mqtt_simple program and I can't seem to find a way to use certificates. I've also been reading through the asset_tracker code and I guess I don't really understand how the certificates work??

[Sigurd]

You can provision the certificate using nrf_inbuilt_key_write(). Example shown here and here.

Or use AT command %CMNG, see this link. If you are running the latest LTE link monitor app, there is now a certificate manager that you can use for the AT command approach:

91dk_at_client_increased_buf.hex

[octvargas]

My question is more of, what function or what procedure checks the certificate against the value the server is looking for. I have A certificate from azure's iot sdk, but I guess I'm not sure where I would put it or what I would do with it

[Sigurd]

octvargas said:

what function or what procedure checks the certificate against the value the server is looking for

 That is handled by the modem fw (where the TLS(1.2)/DTLS(1.2) and TCP/UDP/IPV4/IPV6 Dual Stack is implemented).

octvargas said:

I'm not sure where I would put it or what I would do with it

 I would have tried the method used in e.g. aws_fota sample. Put the certificate in a certificates.h that you create, call provision_certificates() , and configure the MQTT library to be used with TLS. Also set CONFIG_MQTT_LIB_TLS=y in prj.conf, you might also need to set CONFIG_NET_SOCKETS_SOCKOPT_TLS=y

[octvargas]

Thanks! That helps a lot, I'll try it and report back.

Thanks again

[octvargas]

Hi again Sigurd,

So I think I've got this somewhat sorted out, I added a provision_certificates function, added the baltime root certificate that comes w/ the Azure SDK to certificates.h, and was able to configure the prj file. After some debugging of all that, I'm now stuck on this issue: 

once I get into the actual loop, my event handler comes back w/ a result of 5 and fails to connect. 

Any help is appreciated, Thank you

[Sigurd]

What function is returning 5? mqtt_connect() ?

[octvargas]

mqtt_input in the loop, it calls upon several functions which eventually call the event handler.

As you can see the switch statement for the event handler returns "MQTT connect failed: %d" with the result value as the return value

[Sigurd]

How does your main.c look like now ?

Something like this?

/*
 * Copyright (c) 2018 Nordic Semiconductor ASA
 *
 * SPDX-License-Identifier: LicenseRef-BSD-5-Clause-Nordic
 */

#include <zephyr.h>
#include <stdio.h>
#include <uart.h>
#include <string.h>

#include <net/mqtt.h>
#include <net/socket.h>
#include <lte_lc.h>

#include "certificates.h"

#if defined(CONFIG_BSD_LIBRARY)
#include "nrf_inbuilt_key.h"
#endif

/* Buffers for MQTT client. */
static u8_t rx_buffer[CONFIG_MQTT_MESSAGE_BUFFER_SIZE];
static u8_t tx_buffer[CONFIG_MQTT_MESSAGE_BUFFER_SIZE];
static u8_t payload_buf[CONFIG_MQTT_PAYLOAD_BUFFER_SIZE];

/* The mqtt client struct */
static struct mqtt_client client;

/* MQTT Broker details. */
static struct sockaddr_storage broker;

#if defined(CONFIG_MQTT_LIB_TLS)
static struct mqtt_sec_config tls_config;
#endif

/* Connected flag */
static bool connected;

/* File descriptor */
static struct pollfd fds;

#if defined(CONFIG_BSD_LIBRARY)

/**@brief Recoverable BSD library error. */
void bsd_recoverable_error_handler(uint32_t err)
{
	printk("bsdlib recoverable error: %u\n", err);
}

/**@brief Irrecoverable BSD library error. */
void bsd_irrecoverable_error_handler(uint32_t err)
{
	printk("bsdlib irrecoverable error: %u\n", err);

	__ASSERT_NO_MSG(false);
}

#endif /* defined(CONFIG_BSD_LIBRARY) */

/**@brief Function to print strings without null-termination
 */
static void data_print(u8_t *prefix, u8_t *data, size_t len)
{
	char buf[len + 1];

	memcpy(buf, data, len);
	buf[len] = 0;
	printk("%s%s\n", prefix, buf);
}

/**@brief Function to publish data on the configured topic
 */
static int data_publish(struct mqtt_client *c, enum mqtt_qos qos,
	u8_t *data, size_t len)
{
	struct mqtt_publish_param param;

	param.message.topic.qos = qos;
	param.message.topic.topic.utf8 = CONFIG_MQTT_PUB_TOPIC;
	param.message.topic.topic.size = strlen(CONFIG_MQTT_PUB_TOPIC);
	param.message.payload.data = data;
	param.message.payload.len = len;
	param.message_id = sys_rand32_get();
	param.dup_flag = 0;
	param.retain_flag = 0;

	data_print("Publishing: ", data, len);
	printk("to topic: %s len: %u\n",
		CONFIG_MQTT_PUB_TOPIC,
		(unsigned int)strlen(CONFIG_MQTT_PUB_TOPIC));

	return mqtt_publish(c, &param);
}

/**@brief Function to subscribe to the configured topic
 */
static int subscribe(void)
{
	struct mqtt_topic subscribe_topic = {
		.topic = {
			.utf8 = CONFIG_MQTT_SUB_TOPIC,
			.size = strlen(CONFIG_MQTT_SUB_TOPIC)
		},
		.qos = MQTT_QOS_1_AT_LEAST_ONCE
	};

	const struct mqtt_subscription_list subscription_list = {
		.list = &subscribe_topic,
		.list_count = 1,
		.message_id = 1234
	};

	printk("Subscribing to: %s len %u\n", CONFIG_MQTT_SUB_TOPIC,
		(unsigned int)strlen(CONFIG_MQTT_SUB_TOPIC));

	return mqtt_subscribe(&client, &subscription_list);
}

/**@brief Function to read the published payload.
 */
static int publish_get_payload(struct mqtt_client *c, size_t length)
{
	u8_t *buf = payload_buf;
	u8_t *end = buf + length;

	if (length > sizeof(payload_buf)) {
		return -EMSGSIZE;
	}

	while (buf < end) {
		int ret = mqtt_read_publish_payload(c, buf, end - buf);

		if (ret < 0) {
			int err;

			if (ret != -EAGAIN) {
				return ret;
			}

			printk("mqtt_read_publish_payload: EAGAIN\n");

			err = poll(&fds, 1, K_SECONDS(CONFIG_MQTT_KEEPALIVE));
			if (err > 0 && (fds.revents & POLLIN) == POLLIN) {
				continue;
			} else {
				return -EIO;
			}
		}

		if (ret == 0) {
			return -EIO;
		}

		buf += ret;
	}

	return 0;
}

/**@brief MQTT client event handler
 */
void mqtt_evt_handler(struct mqtt_client *const c,
		      const struct mqtt_evt *evt)
{
	int err;
	printk("MQTT EVENT: %d\n", evt->type);

	switch (evt->type) {
	case MQTT_EVT_CONNACK:
		if (evt->result != 0) {
			printk("MQTT connect failed %d\n", evt->result);
			break;
		}

		connected = true;
		printk("[%s:%d] MQTT client connected!\n", __func__, __LINE__);
		subscribe();
		break;

	case MQTT_EVT_DISCONNECT:
		printk("[%s:%d] MQTT client disconnected %d\n", __func__,
		       __LINE__, evt->result);

		connected = false;
		break;

	case MQTT_EVT_PUBLISH: {
		const struct mqtt_publish_param *p = &evt->param.publish;

		printk("[%s:%d] MQTT PUBLISH result=%d len=%d\n", __func__,
		       __LINE__, evt->result, p->message.payload.len);
		err = publish_get_payload(c, p->message.payload.len);
		if (err >= 0) {
			data_print("Received: ", payload_buf,
				p->message.payload.len);
			/* Echo back received data */
			data_publish(&client, MQTT_QOS_1_AT_LEAST_ONCE,
				payload_buf, p->message.payload.len);
		} else {
			printk("mqtt_read_publish_payload: Failed! %d\n", err);
			printk("Disconnecting MQTT client...\n");

			err = mqtt_disconnect(c);
			if (err) {
				printk("Could not disconnect: %d\n", err);
			}
		}
	} break;

	case MQTT_EVT_PUBACK:
		if (evt->result != 0) {
			printk("MQTT PUBACK error %d\n", evt->result);
			break;
		}

		printk("[%s:%d] PUBACK packet id: %u\n", __func__, __LINE__,
				evt->param.puback.message_id);
		break;

	case MQTT_EVT_SUBACK:
		if (evt->result != 0) {
			printk("MQTT SUBACK error %d\n", evt->result);
			break;
		}

		printk("[%s:%d] SUBACK packet id: %u\n", __func__, __LINE__,
				evt->param.suback.message_id);
		break;

	default:
		printk("[%s:%d] default: %d\n", __func__, __LINE__,
				evt->type);
		break;
	}
}

/**@brief Resolves the configured hostname and
 * initializes the MQTT broker structure
 */
static void broker_init(void)
{
	int err;
	struct addrinfo *result;
	struct addrinfo *addr;
	struct addrinfo hints = {
		.ai_family = AF_INET,
		.ai_socktype = SOCK_STREAM
	};

	err = getaddrinfo(CONFIG_MQTT_BROKER_HOSTNAME, NULL, &hints, &result);
	if (err) {
		printk("ERROR: getaddrinfo failed %d\n", err);

		return;
	}

	addr = result;
	err = -ENOENT;

	/* Look for address of the broker. */
	while (addr != NULL) {
		/* IPv4 Address. */
		if (addr->ai_addrlen == sizeof(struct sockaddr_in)) {
			struct sockaddr_in *broker4 =
				((struct sockaddr_in *)&broker);
			char ipv4_addr[NET_IPV4_ADDR_LEN];

			broker4->sin_addr.s_addr =
				((struct sockaddr_in *)addr->ai_addr)
				->sin_addr.s_addr;
			broker4->sin_family = AF_INET;
			broker4->sin_port = htons(CONFIG_MQTT_BROKER_PORT);

			inet_ntop(AF_INET, &broker4->sin_addr.s_addr,
				  ipv4_addr, sizeof(ipv4_addr));
			printk("IPv4 Address found %s\n", ipv4_addr);

			break;
		} else {
			printk("ai_addrlen = %u should be %u or %u\n",
				(unsigned int)addr->ai_addrlen,
				(unsigned int)sizeof(struct sockaddr_in),
				(unsigned int)sizeof(struct sockaddr_in6));
		}

		addr = addr->ai_next;
		break;
	}

	/* Free the address. */
	freeaddrinfo(result);
}

/**@brief Initialize the MQTT client structure
 */
static void client_init(struct mqtt_client *client)
{
	mqtt_client_init(client);

	broker_init();

	/* MQTT client configuration */
	client->broker = &broker;
	client->evt_cb = mqtt_evt_handler;
	client->client_id.utf8 = (u8_t *)CONFIG_MQTT_CLIENT_ID;
	client->client_id.size = strlen(CONFIG_MQTT_CLIENT_ID);
	client->password = NULL;
	client->user_name = NULL;
	client->protocol_version = MQTT_VERSION_3_1_1;

	/* MQTT buffers configuration */
	client->rx_buf = rx_buffer;
	client->rx_buf_size = sizeof(rx_buffer);
	client->tx_buf = tx_buffer;
	client->tx_buf_size = sizeof(tx_buffer);

	/* MQTT transport configuration */
#if defined(CONFIG_MQTT_LIB_TLS)
	client->transport.type = MQTT_TRANSPORT_SECURE;

	//struct mqtt_sec_config *tls_config = &client->transport.tls.config;

	memcpy(&client->transport.tls.config, &tls_config, sizeof(struct mqtt_sec_config));
#else
	client->transport.type = MQTT_TRANSPORT_NON_SECURE;
#endif
}

/**@brief Initialize the file descriptor structure used by poll.
 */
static int fds_init(struct mqtt_client *c)
{
	if (c->transport.type == MQTT_TRANSPORT_NON_SECURE) {
		fds.fd = c->transport.tcp.sock;
	} else {
#if defined(CONFIG_MQTT_LIB_TLS)
		fds.fd = c->transport.tls.sock;
#else
		return -ENOTSUP;
#endif
	}

	fds.events = POLLIN;

	return 0;
}

/**@brief Configures modem to provide LTE link. Blocks until link is
 * successfully established.
 */
static void modem_configure(void)
{
#if defined(CONFIG_LTE_LINK_CONTROL)
	if (IS_ENABLED(CONFIG_LTE_AUTO_INIT_AND_CONNECT)) {
		/* Do nothing, modem is already turned on
		 * and connected.
		 */
	} else {
		int err;

		printk("LTE Link Connecting ...\n");
		err = lte_lc_init_and_connect();
		__ASSERT(err == 0, "LTE link could not be established.");
		printk("LTE Link Connected!\n");
	}
#endif
}

/* Provisions root CA certificate using nrf_inbuilt_key API */
static int mqtt_provision(void)
{
#if defined(CONFIG_MQTT_LIB_TLS)
	static sec_tag_t sec_tag_list[] = {CONFIG_MQTT_SEC_TAG};

	tls_config.peer_verify = 2;
	tls_config.cipher_count = 0;
	tls_config.cipher_list = NULL;
	tls_config.sec_tag_count = ARRAY_SIZE(sec_tag_list);
	tls_config.sec_tag_list = sec_tag_list;
	tls_config.hostname = CONFIG_MQTT_BROKER_HOSTNAME;
#endif

#if defined(CONFIG_MQTT_PROVISION_CERTIFICATES)
#if defined(CONFIG_BSD_LIBRARY)
	{
		int err;

		/* Delete certificates */
		nrf_sec_tag_t sec_tag = CONFIG_MQTT_SEC_TAG;

		for (nrf_key_mgnt_cred_type_t type = 0; type < 5; type++) {
			err = nrf_inbuilt_key_delete(sec_tag, type);
			printk("nrf_inbuilt_key_delete(%lu, %d) => result=%d\n",
				sec_tag, type, err);
		}

		/* Provision CA Certificate. */
		err = nrf_inbuilt_key_write(CONFIG_MQTT_SEC_TAG,
					NRF_KEY_MGMT_CRED_TYPE_CA_CHAIN,
					MQTT_CA_CERTIFICATE,
					strlen(MQTT_CA_CERTIFICATE));
		if (err) {
			printk("MQTT_CA_CERTIFICATE err: %d\n", err);
			return err;
		}

		/* Provision Private Certificate. */
		err = nrf_inbuilt_key_write(
			CONFIG_MQTT_SEC_TAG,
			NRF_KEY_MGMT_CRED_TYPE_PRIVATE_CERT,
			MQTT_CLIENT_PRIVATE_KEY,
			strlen(MQTT_CLIENT_PRIVATE_KEY));
		if (err) {
			printk("MQTT_CLIENT_PRIVATE_KEY err: %d\n", err);
			return err;
		}

		/* Provision Public Certificate. */
		err = nrf_inbuilt_key_write(
			CONFIG_MQTT_SEC_TAG,
			NRF_KEY_MGMT_CRED_TYPE_PUBLIC_CERT,
			MQTT_CLIENT_PUBLIC_CERTIFICATE,
			strlen(MQTT_CLIENT_PUBLIC_CERTIFICATE));
		if (err) {
			printk("MQTT_CLIENT_PUBLIC_CERTIFICATE err: %d\n",
				err);
			return err;
		}
	}
#else
	{
		int err;

		err = tls_credential_add(CONFIG_MQTT_SEC_TAG,
			TLS_CREDENTIAL_CA_CERTIFICATE,
			MQTT_CA_CERTIFICATE,
			sizeof(MQTT_CA_CERTIFICATE));
		if (err < 0) {
			printk("Failed to register ca certificate: %d\n",
				err);
			return err;
		}
		err = tls_credential_add(CONFIG_MQTT_SEC_TAG,
			TLS_CREDENTIAL_PRIVATE_KEY,
			MQTT_CLIENT_PRIVATE_KEY,
			sizeof(MQTT_CLIENT_PRIVATE_KEY));
		if (err < 0) {
			printk("Failed to register private key: %d\n",
				err);
			return err;
		}
		err = tls_credential_add(CONFIG_MQTT_SEC_TAG,
			TLS_CREDENTIAL_SERVER_CERTIFICATE,
			MQTT_CLIENT_PUBLIC_CERTIFICATE,
			sizeof(MQTT_CLIENT_PUBLIC_CERTIFICATE));
		if (err < 0) {
			printk("Failed to register public certificate: %d\n",
				err);
			return err;
		}

	}
#endif /* defined(CONFIG_BSD_LIBRARY) */
#endif /* defined(CONFIG_MQTT_PROVISION_CERTIFICATES) */

	return 0;
}

void main(void)
{
	int err;

	printk("The MQTT simple sample started\n");

	err = mqtt_provision();
	if (err != 0) {
		printk("ERROR: mqtt_provision %d\n", err);
		return;
	}

	modem_configure();

	client_init(&client);

	err = mqtt_connect(&client);
	if (err != 0) {
		printk("ERROR: mqtt_connect %d\n", err);
		return;
	}

	err = fds_init(&client);
	if (err != 0) {
		printk("ERROR: fds_init %d\n", err);
		return;
	}

	while (1) {
		err = poll(&fds, 1, K_SECONDS(CONFIG_MQTT_KEEPALIVE));
		if (err < 0) {
			printk("ERROR: poll %d\n", errno);
			break;
		}

		err = mqtt_live(&client);
		if (err != 0) {
			printk("ERROR: mqtt_live %d\n", err);
			break;
		}

		if ((fds.revents & POLLIN) == POLLIN) {
			err = mqtt_input(&client);
			if (err != 0) {
				printk("ERROR: mqtt_input %d\n", err);
				break;
			}
		}

		if ((fds.revents & POLLERR) == POLLERR) {
			printk("POLLERR\n");
			break;
		}

		if ((fds.revents & POLLNVAL) == POLLNVAL) {
			printk("POLLNVAL\n");
			break;
		}
	}

	printk("Disconnecting MQTT client...\n");

	err = mqtt_disconnect(&client);
	if (err) {
		printk("Could not disconnect MQTT client. Error: %d\n", err);
	}
}

# General config
CONFIG_TEST_RANDOM_GENERATOR=y

# Networking
CONFIG_NETWORKING=y
CONFIG_NET_SOCKETS_OFFLOAD=y
CONFIG_NET_SOCKETS=y
CONFIG_NET_SOCKETS_POSIX_NAMES=y

# LTE link control
CONFIG_LTE_LINK_CONTROL=y
CONFIG_LTE_AUTO_INIT_AND_CONNECT=n

# BSD library
CONFIG_BSD_LIBRARY=y

# AT Host
CONFIG_UART_INTERRUPT_DRIVEN=y
CONFIG_AT_HOST_LIBRARY=y

# MQTT
CONFIG_MQTT_LIB=y
CONFIG_MQTT_LIB_TLS=y

# Appliaction
CONFIG_MQTT_PUB_TOPIC="YOUR_PUB_TOPIC"
CONFIG_MQTT_SUB_TOPIC="YOU_SUB_TOPIC"
CONFIG_MQTT_CLIENT_ID="YOUR_CLIENT_ID"
CONFIG_MQTT_BROKER_HOSTNAME="YOUR_HOSTNAME"
CONFIG_MQTT_BROKER_PORT=8883
CONFIG_MQTT_PROVISION_CERTIFICATES=y

# Main thread
CONFIG_MAIN_THREAD_PRIORITY=7
CONFIG_MAIN_STACK_SIZE=4096

CONFIG_HEAP_MEM_POOL_SIZE=1024

# Disable native network stack to save some memory
CONFIG_NET_IPV4=n
CONFIG_NET_IPV6=n
CONFIG_NET_UDP=n
CONFIG_NET_TCP=n

CONFIG_LOG=y
CONFIG_LOG_BACKEND_SHOW_COLOR=n
CONFIG_MQTT_LOG_LEVEL_DBG=y
CONFIG_NET_LOG=y

[octvargas]

let me edit my files to remove any sensitive information and i'll post it