main_dtls.c

/*
 * Copyright 2019-2024 u-blox
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/** @brief This example demonstrates bringing up a network
 * and performing socket operations over a secured UDP (i.e. DTLS)
 * connection with a u-blox module.
 *
 * The choice of module and the choice of platform on which this
 * code runs is made at build time, see the README.md for
 * instructions.
 */

// Bring in all of the ubxlib public header files
#include "ubxlib.h"

// Bring in the application settings
#include "u_cfg_app_platform_specific.h"

// The specific credentials provided for use with this example,
// must use quoted includes to pick up the local file without it
// having to be on the include path
#include "credentials_tls.h"

#ifndef U_CFG_DISABLE_TEST_AUTOMATION
// This purely for internal u-blox testing
# include "u_cfg_test_platform_specific.h"
#endif

#include <string.h> // For memcmp() and strlen()

/* ----------------------------------------------------------------
 * COMPILE-TIME MACROS
 * -------------------------------------------------------------- */

// Echo server URL and port number
#define MY_SERVER_NAME "ubxlib.com"
#define MY_SERVER_PORT 5070

// For u-blox internal testing only
#ifdef U_PORT_TEST_ASSERT
# define EXAMPLE_FINAL_STATE(x) U_PORT_TEST_ASSERT(x);
#else
# define EXAMPLE_FINAL_STATE(x)
#endif

#ifndef U_PORT_TEST_FUNCTION
# error if you are not using the unit test framework to run this code you must ensure that the platform clocks/RTOS are set up and either define U_PORT_TEST_FUNCTION yourself or replace it as necessary.
#endif

/* ----------------------------------------------------------------
 * TYPES
 * -------------------------------------------------------------- */

/* ----------------------------------------------------------------
 * VARIABLES
 * -------------------------------------------------------------- */

// ZEPHYR USERS may prefer to set the device and network
// configuration from their device tree, rather than in this C
// code: see /port/platform/zephyr/README.md for instructions on
// how to do that.

// Cellular configuration.
// Set U_CFG_TEST_CELL_MODULE_TYPE to your module type,
// chosen from the values in cell/api/u_cell_module_type.h
//
// Note that the pin numbers are those of the MCU: if you
// are using an MCU inside a u-blox module the IO pin numbering
// for the module is likely different to that of the MCU: check
// the data sheet for the module to determine the mapping.

#if defined(U_CFG_TEST_CELL_MODULE_TYPE) && !defined(U_CFG_TEST_TRANSPORT_SECURITY_DISABLE)
// DEVICE i.e. module/chip configuration: in this case a cellular
// module connected via UART
static const uDeviceCfg_t gDeviceCfg = {
    .deviceType = U_DEVICE_TYPE_CELL,
    .deviceCfg = {
        .cfgCell = {
            .moduleType = U_CFG_TEST_CELL_MODULE_TYPE,
            .pSimPinCode = NULL, /* SIM pin */
            .pinEnablePower = U_CFG_APP_PIN_CELL_ENABLE_POWER,
            .pinPwrOn = U_CFG_APP_PIN_CELL_PWR_ON,
            .pinVInt = U_CFG_APP_PIN_CELL_VINT,
            .pinDtrPowerSaving = U_CFG_APP_PIN_CELL_DTR
        },
    },
    .transportType = U_DEVICE_TRANSPORT_TYPE_UART,
    .transportCfg = {
        .cfgUart = {
            .uart = U_CFG_APP_CELL_UART,
            .baudRate = U_CELL_UART_BAUD_RATE,
            .pinTxd = U_CFG_APP_PIN_CELL_TXD,  // Use -1 if on Zephyr or Linux or Windows
            .pinRxd = U_CFG_APP_PIN_CELL_RXD,  // Use -1 if on Zephyr or Linux or Windows
            .pinCts = U_CFG_APP_PIN_CELL_CTS,  // Use -1 if on Zephyr
            .pinRts = U_CFG_APP_PIN_CELL_RTS,  // Use -1 if on Zephyr
#ifdef U_CFG_APP_UART_PREFIX
            .pPrefix = U_PORT_STRINGIFY_QUOTED(U_CFG_APP_UART_PREFIX) // Relevant for Linux only
#else
            .pPrefix = NULL
#endif
        },
    },
};
// NETWORK configuration for cellular
static const uNetworkCfgCell_t gNetworkCfg = {
    .type = U_NETWORK_TYPE_CELL,
    .pApn = NULL, /* APN: NULL to accept default.  If using a Thingstream SIM enter "tsiot" here */
    .timeoutSeconds = 240 /* Connection timeout in seconds */
    // There are six additional fields here which we do NOT set,
    // we allow the compiler to set them to 0 and all will be fine.
    // The fields are:
    //
    // - "pKeepGoingCallback": you may set this field to a function
    //   of the form "bool keepGoingCallback(uDeviceHandle_t devHandle)",
    //   e.g.:
    //
    //   .pKeepGoingCallback = keepGoingCallback;
    //
    //   ...and your function will be called periodically during an
    //   abortable network operation such as connect/disconnect;
    //   if it returns true the operation will continue else it
    //   will be aborted, allowing you immediate control.  If this
    //   field is set, timeoutSeconds will be ignored.
    //
    // - "pUsername" and "pPassword": if you are required to set a
    //   user name and password to go with the APN value that you
    //   were given by your service provider, set them here.
    //
    // - "authenticationMode": if you MUST give a user name and
    //   password and your cellular module does NOT support figuring
    //   out the authentication mode automatically (e.g. SARA-R4xx,
    //   LARA-R6 and LENA-R8 do not) then you must populate this field
    //   with the authentication mode that should be used, see
    //   #uCellNetAuthenticationMode_t in u_cell_net.h; there is no
    //   harm in populating this field even if the module _does_ support
    //   figuring out the authentication mode automatically but
    //   you ONLY NEED TO WORRY ABOUT IT if you were given that user
    //   name and password with the APN (which is thankfully not usual).
    //
    // - "pMccMnc": ONLY required if you wish to connect to a specific
    //   MCC/MNC rather than to the best available network; should point
    //   to the null-terminated string giving the MCC and MNC of the PLMN
    //   to use (for example "23410").
    //
    // - "pUartPpp": ONLY REQUIRED if U_CFG_PPP_ENABLE is defined AND
    //   you wish to run a PPP interface to the cellular module over a
    //   DIFFERENT serial port to that which was specified in the device
    //   configuration passed to uDeviceOpen().  This is useful if you
    //   are using the USB interface of a cellular module, which does not
    //   support the CMUX protocol that multiplexes PPP with AT.
};
#else
// No module available - set some dummy values to make test system happy
static const uDeviceCfg_t gDeviceCfg = {.deviceType = U_DEVICE_TYPE_NONE};
static const uNetworkCfgCell_t gNetworkCfg = {.type = U_NETWORK_TYPE_NONE};
#endif

// TODO: Wifi network configuration.

/* ----------------------------------------------------------------
 * STATIC FUNCTIONS
 * -------------------------------------------------------------- */

// Print out an address structure.
static void printAddress(const uSockAddress_t *pAddress,
                         bool hasPort)
{
    switch (pAddress->ipAddress.type) {
        case U_SOCK_ADDRESS_TYPE_V4:
            uPortLog("IPV4");
            break;
        case U_SOCK_ADDRESS_TYPE_V6:
            uPortLog("IPV6");
            break;
        case U_SOCK_ADDRESS_TYPE_V4_V6:
            uPortLog("IPV4V6");
            break;
        default:
            uPortLog("unknown type (%d)", pAddress->ipAddress.type);
            break;
    }

    uPortLog(" ");

    if (pAddress->ipAddress.type == U_SOCK_ADDRESS_TYPE_V4) {
        for (int32_t x = 3; x >= 0; x--) {
            uPortLog("%u",
                     (pAddress->ipAddress.address.ipv4 >> (x * 8)) & 0xFF);
            if (x > 0) {
                uPortLog(".");
            }
        }
        if (hasPort) {
            uPortLog(":%u", pAddress->port);
        }
    } else if (pAddress->ipAddress.type == U_SOCK_ADDRESS_TYPE_V6) {
        if (hasPort) {
            uPortLog("[");
        }
        for (int32_t x = 3; x >= 0; x--) {
            uPortLog("%x:%x", pAddress->ipAddress.address.ipv6[x] >> 16,
                     pAddress->ipAddress.address.ipv6[x] & 0xFFFF);
            if (x > 0) {
                uPortLog(":");
            }
        }
        if (hasPort) {
            uPortLog("]:%u", pAddress->port);
        }
    }
}

// Check that the credentials have been loaded.
static void checkCredentials(uDeviceHandle_t devHandle,
                             uSecurityTlsSettings_t *pSettings)
{
    char hash[U_SECURITY_CREDENTIAL_MD5_LENGTH_BYTES];

    // Check if the client certificate is already
    // stored on the module
    if ((uSecurityCredentialGetHash(devHandle,
                                    U_SECURITY_CREDENTIAL_CLIENT_X509,
                                    "ubxlib_test_client_cert",
                                    hash) != 0) ||
        (memcmp(hash, gUEchoServerClientCertHash, sizeof(hash)) != 0)) {
        // Either it is not there or the wrong hash has been
        // reported, load the client certificate into the module
        uSecurityCredentialStore(devHandle,
                                 U_SECURITY_CREDENTIAL_CLIENT_X509,
                                 "ubxlib_test_client_cert",
                                 gpUEchoServerClientCertPem,
                                 strlen(gpUEchoServerClientCertPem),
                                 NULL, NULL);
    }
    pSettings->pClientCertificateName = "ubxlib_test_client_cert";

    // Check if the client key is already stored on the module
    if ((uSecurityCredentialGetHash(devHandle,
                                    U_SECURITY_CREDENTIAL_CLIENT_KEY_PRIVATE,
                                    "ubxlib_test_client_key",
                                    hash) != 0) ||
        (memcmp(hash, gUEchoServerClientKeyHash, sizeof(hash)) != 0)) {
        // Either it is not there or the wrong hash has been
        // reported, load the client key into the module
        uSecurityCredentialStore(devHandle,
                                 U_SECURITY_CREDENTIAL_CLIENT_KEY_PRIVATE,
                                 "ubxlib_test_client_key",
                                 gpUEchoServerClientKeyPem,
                                 strlen(gpUEchoServerClientKeyPem),
                                 NULL, NULL);
    }
    pSettings->pClientPrivateKeyName = "ubxlib_test_client_key";

    // Check if the CA certificate is already
    // stored on the module
    if ((uSecurityCredentialGetHash(devHandle,
                                    U_SECURITY_CREDENTIAL_ROOT_CA_X509,
                                    "ubxlib_test_ca_cert",
                                    hash) != 0) ||
        (memcmp(hash, gUEchoServerCaCertHash, sizeof(hash)) != 0)) {
        // Either it is not there or the wrong hash has been
        // reported, load the CA certificate into the module
        // as a trusted key
        // IMPORTANT: in the real world you would not need to do
        // this, you would have root certificates loaded to do the
        // job.  We are only doing it here because the ubxlib echo
        // server is simply for testing and therefore not part of
        // any chain of trust
        uPortLog("U_SECURITY_TLS_TEST: storing CA certificate...\n");
        uSecurityCredentialStore(devHandle,
                                 U_SECURITY_CREDENTIAL_ROOT_CA_X509,
                                 "ubxlib_test_ca_cert",
                                 gpUEchoServerCaCertPem,
                                 strlen(gpUEchoServerCaCertPem),
                                 NULL, NULL);
    }
    pSettings->pRootCaCertificateName = "ubxlib_test_ca_cert";
}

/* ----------------------------------------------------------------
 * PUBLIC FUNCTIONS: THE EXAMPLE
 * -------------------------------------------------------------- */

// The entry point, main(): before this is called the system
// clocks must have been started and the RTOS must be running;
// we are in task space.
U_PORT_TEST_FUNCTION("[example]", "exampleSocketsDtls")
{
    uDeviceHandle_t devHandle = NULL;
    int32_t sock;
    int32_t x = 0;
    uSockAddress_t address;
    const char message[] = "The quick brown fox jumps over the lazy dog.";
    size_t txSize = sizeof(message);
    char buffer[64];
    size_t rxSize = 0;
    int32_t returnCode;
    uSecurityTlsSettings_t settings = U_SECURITY_TLS_SETTINGS_DEFAULT;

    // Add certificate checking to the security settings
    settings.certificateCheck = U_SECURITY_TLS_CERTIFICATE_CHECK_ROOT_CA;

    // Initialise the APIs we will need
    uPortInit();
    uDeviceInit();

    // Open the device
    returnCode = uDeviceOpen(&gDeviceCfg, &devHandle);
    uPortLog("Opened device with return code %d.\n", returnCode);

    if (returnCode == 0) {
        // Bring up the network interface
        uPortLog("Bringing up the network...\n");
        if (uNetworkInterfaceUp(devHandle, U_NETWORK_TYPE_CELL,
                                &gNetworkCfg) == 0) {

            // Do things using the network, for
            // example connect and send data to
            // an echo server over a TCP socket
            // as follows

            // Get the server's IP address using
            // the network's DNS resolution facility
            uPortLog("Looking up server address...\n");
            uSockGetHostByName(devHandle, MY_SERVER_NAME,
                               &(address.ipAddress));
            uPortLog("Address is: ");
            printAddress(&address, false);
            address.port = MY_SERVER_PORT;
            uPortLog("\n");

            // Check that the relevant credentials
            // have been loaded
            checkCredentials(devHandle, &settings);

            // Create the socket on the network
            uPortLog("Creating socket...\n");
            sock = uSockCreate(devHandle,
                               U_SOCK_TYPE_DGRAM,
                               U_SOCK_PROTOCOL_UDP);

            // Secure the socket.  Before calling this
            // you would make any changes to settings
            // that you wished.  By default only
            // end to end encryption will be performed
            // but, having loaded the credentials above,
            // we will pass the client certificate to
            // the server on request and some modules
            // (e.g. SARA-R5) will also by default confirm
            // the server's authenticity
            if (uSockSecurity(sock, &settings) == 0) {
                // For DTLS the socket must be connected,
                // even though we are using UDP
                if (uSockConnect(sock, &address) == 0) {
                    // Send the data over the socket
                    // and print the echo that comes back
                    uPortLog("Sending data...\n");
                    while ((x >= 0) && (txSize > 0)) {
                        x = uSockWrite(sock, message + (sizeof(message) - txSize), txSize);
                        if (x > 0) {
                            txSize -= x;
                        }
                    }
                    uPortLog("Sent %d byte(s) to echo server.\n", sizeof(message) - txSize);
                    while ((x >= 0) && (rxSize < sizeof(message))) {
                        x = uSockRead(sock, buffer + rxSize, sizeof(buffer) - rxSize);
                        if (x > 0) {
                            rxSize += x;
                        }
                    }
                    if (rxSize > 0) {
                        uPortLog("\nReceived echo back (%d byte(s)): %s\n", rxSize, buffer);
                    } else {
                        uPortLog("\nNo reply received!\n");
                    }
                } else {
                    uPortLog("Unable to connect to server!\n");
                }

                // Note: since devHandle is a cellular
                // handle any of the `cell` API calls
                // could be made here using it.
                // If the configuration used were Wifi
                // then the `wifi` API calls could be
                // used

                // Close the socket
                uPortLog("Closing socket...\n");
                uSockShutdown(sock, U_SOCK_SHUTDOWN_READ_WRITE);
                uSockClose(sock);
                uSockCleanUp();

                // When finished with the network layer
                uPortLog("Taking down network...\n");
                uNetworkInterfaceDown(devHandle, U_NETWORK_TYPE_CELL);
            } else {
                uPortLog("Unable to secure socket!\n");
            }
        } else {
            uPortLog("Unable to bring up the network!\n");
        }

        // Close the device
        // Note: we don't power the device down here in order
        // to speed up testing; you may prefer to power it off
        // by setting the second parameter to true.
        uDeviceClose(devHandle, false);

    } else {
        uPortLog("Unable to bring up the device!\n");
    }

    // Tidy up
    uDeviceDeinit();
    uPortDeinit();

    uPortLog("Done.\n");

#if defined(U_CFG_TEST_CELL_MODULE_TYPE) && !defined(U_CFG_TEST_TRANSPORT_SECURITY_DISABLE)
    // For u-blox internal testing only
    EXAMPLE_FINAL_STATE((txSize == 0) && (rxSize == sizeof(message)));
#endif
}

// End of file