src/core/meshcop/dtls.hpp

/*
 *  Copyright (c) 2016, The OpenThread Authors.
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 *     notice, this list of conditions and the following disclaimer.
 *  2. Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *  3. Neither the name of the copyright holder nor the
 *     names of its contributors may be used to endorse or promote products
 *     derived from this software without specific prior written permission.
 *
 *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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 */

/**
 * @file
 *   This file includes definitions for using mbedTLS.
 */

#ifndef DTLS_HPP_
#define DTLS_HPP_

#include <openthread/types.h>

#include <mbedtls/ssl.h>
#include <mbedtls/entropy.h>
#include <mbedtls/ctr_drbg.h>
#include <mbedtls/error.h>
#include <mbedtls/certs.h>
#include <mbedtls/ssl_cookie.h>

#include "common/locator.hpp"
#include "common/message.hpp"
#include "common/timer.hpp"
#include "crypto/sha256.hpp"
#include "meshcop/meshcop_tlvs.hpp"

namespace ot {

class ThreadNetif;

namespace MeshCoP {

class Dtls: public ThreadNetifLocator
{
public:
    enum
    {
        kPskMaxLength = 32,
        kApplicationDataMaxLength = 128,
    };

    /**
     * This constructor initializes the DTLS object.
     *
     * @param[in]  aNetif  A reference to the Thread network interface.
     *
     */
    Dtls(ThreadNetif &aNetif);

    /**
     * This function pointer is called when a connection is established or torn down.
     *
     * @param[in]  aContext    A pointer to application-specific context.
     * @param[in]  aConnected  TRUE if a connection was established, FALSE otherwise.
     *
     */
    typedef void (*ConnectedHandler)(void *aContext, bool aConnected);

    /**
     * This function pointer is called when data is received from the DTLS session.
     *
     * @param[in]  aContext  A pointer to application-specific context.
     * @param[in]  aBuf      A pointer to the received data buffer.
     * @param[in]  aLength   Number of bytes in the received data buffer.
     *
     */
    typedef void (*ReceiveHandler)(void *aContext, uint8_t *aBuf, uint16_t aLength);

    /**
     * This function pointer is called when data is ready to transmit for the DTLS session.
     *
     * @param[in]  aContext         A pointer to application-specific context.
     * @param[in]  aBuf             A pointer to the transmit data buffer.
     * @param[in]  aLength          Number of bytes in the transmit data buffer.
     * @param[in]  aMessageSubtype  A message sub type information for the sender.
     *
     */
    typedef otError(*SendHandler)(void *aContext, const uint8_t *aBuf, uint16_t aLength, uint8_t aMessageSubType);

    /**
     * This method starts the DTLS service.
     *
     * @param[in]  aClient            TRUE if operating as a client, FALSE if operating as a server.
     * @param[in]  aConnectedHandler  A pointer to the connected handler.
     * @param[in]  aReceiveHandler    A pointer to the receive handler.
     * @param[in]  aSendHandler       A pointer to the send handler.
     * @param[in]  aContext           A pointer to application-specific context.
     *
     * @retval OT_ERROR_NONE      Successfully started the DTLS service.
     *
     */
    otError Start(bool aClient, ConnectedHandler aConnectedHandler, ReceiveHandler aReceiveHandler,
                  SendHandler aSendHandler, void *aContext);

    /**
     * This method stops the DTLS service.
     *
     * @retval OT_ERROR_NONE  Successfully stopped the DTLS service.
     *
     */
    otError Stop(void);

    /**
     * This method indicates whether or not the DTLS service is active.
     *
     * @returns TRUE if the DTLS service is active, FALSE otherwise.
     *
     */
    bool IsStarted(void);

    /**
     * This method sets the PSK.
     *
     * @param[in]  aPSK  A pointer to the PSK.
     *
     * @retval OT_ERROR_NONE          Successfully set the PSK.
     * @retval OT_ERROR_INVALID_ARGS  The PSK is invalid.
     *
     */
    otError SetPsk(const uint8_t *aPsk, uint8_t aPskLength);

    /**
     * This method sets the Client ID used for generating the Hello Cookie.
     *
     * @param[in]  aClientId  A pointer to the Client ID.
     * @param[in]  aLength    Number of bytes in the Client ID.
     *
     * @retval OT_ERROR_NONE  Successfully set the Client ID.
     *
     */
    otError SetClientId(const uint8_t *aClientId, uint8_t aLength);

    /**
     * This method indicates whether or not the DTLS session is connected.
     *
     * @retval TRUE   The DTLS session is connected.
     * @retval FALSE  The DTLS session is not connected.
     *
     */
    bool IsConnected(void);

    /**
     * This method sends data within the DTLS session.
     *
     * @param[in]  aMessage  A message to send via DTLS.
     * @param[in]  aLength   Number of bytes in the data buffer.
     *
     * @retval OT_ERROR_NONE     Successfully sent the data via the DTLS session.
     * @retval OT_ERROR_NO_BUFS  A message is too long.
     *
     */
    otError Send(Message &aMessage, uint16_t aLength);

    /**
     * This method provides a received DTLS message to the DTLS object.
     *
     * @param[in]  aMessage  A reference to the message.
     * @param[in]  aOffset   The offset within @p aMessage where the DTLS message starts.
     * @param[in]  aLength   The size of the DTLS message (bytes).
     *
     * @retval OT_ERROR_NONE  Successfully processed the received DTLS message.
     *
     */
    otError Receive(Message &aMessage, uint16_t aOffset, uint16_t aLength);

    /**
     * The provisioning URL is placed here so that both the Commissioner and Joiner can share the same object.
     *
     */
    ProvisioningUrlTlv mProvisioningUrl;

private:
    static otError MapError(int rval);

    static void HandleMbedtlsDebug(void *ctx, int level, const char *file, int line, const char *str);

    static int HandleMbedtlsGetTimer(void *aContext);
    int HandleMbedtlsGetTimer(void);

    static void HandleMbedtlsSetTimer(void *aContext, uint32_t aIntermediate, uint32_t aFinish);
    void HandleMbedtlsSetTimer(uint32_t aIntermediate, uint32_t aFinish);

    static int HandleMbedtlsReceive(void *aContext, unsigned char *aBuf, size_t aLength);
    int HandleMbedtlsReceive(unsigned char *aBuf, size_t aLength);

    static int HandleMbedtlsTransmit(void *aContext, const unsigned char *aBuf, size_t aLength);
    int HandleMbedtlsTransmit(const unsigned char *aBuf, size_t aLength);

    static int HandleMbedtlsExportKeys(void *aContext, const unsigned char *aMasterSecret,
                                       const unsigned char *aKeyBlock,
                                       size_t aMacLength, size_t aKeyLength, size_t aIvLength);
    int HandleMbedtlsExportKeys(const unsigned char *aMasterSecret, const unsigned char *aKeyBlock,
                                size_t aMacLength, size_t aKeyLength, size_t aIvLength);

    static void HandleTimer(Timer &aTimer);
    void HandleTimer(void);

    void Close(void);
    void Process(void);

    static Dtls &GetOwner(const Context &aContext);

    uint8_t mPsk[kPskMaxLength];
    uint8_t mPskLength;

    mbedtls_entropy_context mEntropy;
    mbedtls_ctr_drbg_context mCtrDrbg;
    mbedtls_ssl_context mSsl;
    mbedtls_ssl_config mConf;
    mbedtls_ssl_cookie_ctx mCookieCtx;
    bool mStarted;

    Timer mTimer;
    uint32_t mTimerIntermediate;
    bool mTimerSet;

    Message *mReceiveMessage;
    uint16_t mReceiveOffset;
    uint16_t mReceiveLength;

    ConnectedHandler mConnectedHandler;
    ReceiveHandler mReceiveHandler;
    SendHandler mSendHandler;
    void *mContext;
    bool mClient;

    uint8_t mMessageSubType;
};

}  // namespace MeshCoP
}  // namespace ot

#endif  // DTLS_HPP_