ssl_internal.h

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/*
 *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
 *  SPDX-License-Identifier: Apache-2.0
 *
 *  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.
 *
 *  This file is part of mbed TLS (https://tls.mbed.org)
 */
#ifndef MBEDTLS_SSL_INTERNAL_H
#define MBEDTLS_SSL_INTERNAL_H

#include "ssl.h"
#include "cipher.h"

#if defined(MBEDTLS_MD5_C)
#include "md5.h"
#endif

#if defined(MBEDTLS_SHA1_C)
#include "sha1.h"
#endif

#if defined(MBEDTLS_SHA256_C)
#include "sha256.h"
#endif

#if defined(MBEDTLS_SHA512_C)
#include "sha512.h"
#endif

#if defined(MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED)
#include "ecjpake.h"
#endif

#if ( defined(__ARMCC_VERSION) || defined(_MSC_VER) ) && \
    !defined(inline) && !defined(__cplusplus)
#define inline __inline
#endif

/* Determine minimum supported version */
#define MBEDTLS_SSL_MIN_MAJOR_VERSION           MBEDTLS_SSL_MAJOR_VERSION_3

#if defined(MBEDTLS_SSL_PROTO_SSL3)
#define MBEDTLS_SSL_MIN_MINOR_VERSION           MBEDTLS_SSL_MINOR_VERSION_0
#else
#if defined(MBEDTLS_SSL_PROTO_TLS1)
#define MBEDTLS_SSL_MIN_MINOR_VERSION           MBEDTLS_SSL_MINOR_VERSION_1
#else
#if defined(MBEDTLS_SSL_PROTO_TLS1_1)
#define MBEDTLS_SSL_MIN_MINOR_VERSION           MBEDTLS_SSL_MINOR_VERSION_2
#else
#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
#define MBEDTLS_SSL_MIN_MINOR_VERSION           MBEDTLS_SSL_MINOR_VERSION_3
#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
#endif /* MBEDTLS_SSL_PROTO_TLS1_1 */
#endif /* MBEDTLS_SSL_PROTO_TLS1   */
#endif /* MBEDTLS_SSL_PROTO_SSL3   */

#define MBEDTLS_SSL_MIN_VALID_MINOR_VERSION MBEDTLS_SSL_MINOR_VERSION_1
#define MBEDTLS_SSL_MIN_VALID_MAJOR_VERSION MBEDTLS_SSL_MAJOR_VERSION_3

/* Determine maximum supported version */
#define MBEDTLS_SSL_MAX_MAJOR_VERSION           MBEDTLS_SSL_MAJOR_VERSION_3

#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
#define MBEDTLS_SSL_MAX_MINOR_VERSION           MBEDTLS_SSL_MINOR_VERSION_3
#else
#if defined(MBEDTLS_SSL_PROTO_TLS1_1)
#define MBEDTLS_SSL_MAX_MINOR_VERSION           MBEDTLS_SSL_MINOR_VERSION_2
#else
#if defined(MBEDTLS_SSL_PROTO_TLS1)
#define MBEDTLS_SSL_MAX_MINOR_VERSION           MBEDTLS_SSL_MINOR_VERSION_1
#else
#if defined(MBEDTLS_SSL_PROTO_SSL3)
#define MBEDTLS_SSL_MAX_MINOR_VERSION           MBEDTLS_SSL_MINOR_VERSION_0
#endif /* MBEDTLS_SSL_PROTO_SSL3   */
#endif /* MBEDTLS_SSL_PROTO_TLS1   */
#endif /* MBEDTLS_SSL_PROTO_TLS1_1 */
#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */

/* Shorthand for restartable ECC */
#if defined(MBEDTLS_ECP_RESTARTABLE) && \
    defined(MBEDTLS_SSL_CLI_C) && \
    defined(MBEDTLS_SSL_PROTO_TLS1_2) && \
    defined(MBEDTLS_KEY_EXCHANGE_ECDHE_ECDSA_ENABLED)
#define MBEDTLS_SSL__ECP_RESTARTABLE
#endif

#define MBEDTLS_SSL_INITIAL_HANDSHAKE           0
#define MBEDTLS_SSL_RENEGOTIATION_IN_PROGRESS   1   /* In progress */
#define MBEDTLS_SSL_RENEGOTIATION_DONE          2   /* Done or aborted */
#define MBEDTLS_SSL_RENEGOTIATION_PENDING       3   /* Requested (server only) */

/*
 * DTLS retransmission states, see RFC 6347 4.2.4
 *
 * The SENDING state is merged in PREPARING for initial sends,
 * but is distinct for resends.
 *
 * Note: initial state is wrong for server, but is not used anyway.
 */
#define MBEDTLS_SSL_RETRANS_PREPARING       0
#define MBEDTLS_SSL_RETRANS_SENDING         1
#define MBEDTLS_SSL_RETRANS_WAITING         2
#define MBEDTLS_SSL_RETRANS_FINISHED        3

/*
 * Allow extra bytes for record, authentication and encryption overhead:
 * counter (8) + header (5) + IV(16) + MAC (16-48) + padding (0-256)
 * and allow for a maximum of 1024 of compression expansion if
 * enabled.
 */
#if defined(MBEDTLS_ZLIB_SUPPORT)
#define MBEDTLS_SSL_COMPRESSION_ADD          1024
#else
#define MBEDTLS_SSL_COMPRESSION_ADD             0
#endif

#if defined(MBEDTLS_ARC4_C) || defined(MBEDTLS_CIPHER_MODE_CBC)
/* Ciphersuites using HMAC */
#if defined(MBEDTLS_SHA512_C)
#define MBEDTLS_SSL_MAC_ADD                 48  /* SHA-384 used for HMAC */
#elif defined(MBEDTLS_SHA256_C)
#define MBEDTLS_SSL_MAC_ADD                 32  /* SHA-256 used for HMAC */
#else
#define MBEDTLS_SSL_MAC_ADD                 20  /* SHA-1   used for HMAC */
#endif
#else
/* AEAD ciphersuites: GCM and CCM use a 128 bits tag */
#define MBEDTLS_SSL_MAC_ADD                 16
#endif

#if defined(MBEDTLS_CIPHER_MODE_CBC)
#define MBEDTLS_SSL_PADDING_ADD            256
#else
#define MBEDTLS_SSL_PADDING_ADD              0
#endif

#define MBEDTLS_SSL_PAYLOAD_OVERHEAD ( MBEDTLS_SSL_COMPRESSION_ADD +    \
                                       MBEDTLS_MAX_IV_LENGTH +          \
                                       MBEDTLS_SSL_MAC_ADD +            \
                                       MBEDTLS_SSL_PADDING_ADD          \
                                       )

#define MBEDTLS_SSL_IN_PAYLOAD_LEN ( MBEDTLS_SSL_PAYLOAD_OVERHEAD + \
                                     ( MBEDTLS_SSL_IN_CONTENT_LEN ) )

#define MBEDTLS_SSL_OUT_PAYLOAD_LEN ( MBEDTLS_SSL_PAYLOAD_OVERHEAD + \
                                      ( MBEDTLS_SSL_OUT_CONTENT_LEN ) )

/* The maximum number of buffered handshake messages. */
#define MBEDTLS_SSL_MAX_BUFFERED_HS 4

/* Maximum length we can advertise as our max content length for
   RFC 6066 max_fragment_length extension negotiation purposes
   (the lesser of both sizes, if they are unequal.)
 */
#define MBEDTLS_TLS_EXT_ADV_CONTENT_LEN (                            \
        (MBEDTLS_SSL_IN_CONTENT_LEN > MBEDTLS_SSL_OUT_CONTENT_LEN)   \
        ? ( MBEDTLS_SSL_OUT_CONTENT_LEN )                            \
        : ( MBEDTLS_SSL_IN_CONTENT_LEN )                             \
        )

/*
 * Check that we obey the standard's message size bounds
 */

#if MBEDTLS_SSL_MAX_CONTENT_LEN > 16384
#error "Bad configuration - record content too large."
#endif

#if MBEDTLS_SSL_IN_CONTENT_LEN > MBEDTLS_SSL_MAX_CONTENT_LEN
#error "Bad configuration - incoming record content should not be larger than MBEDTLS_SSL_MAX_CONTENT_LEN."
#endif

#if MBEDTLS_SSL_OUT_CONTENT_LEN > MBEDTLS_SSL_MAX_CONTENT_LEN
#error "Bad configuration - outgoing record content should not be larger than MBEDTLS_SSL_MAX_CONTENT_LEN."
#endif

#if MBEDTLS_SSL_IN_PAYLOAD_LEN > MBEDTLS_SSL_MAX_CONTENT_LEN + 2048
#error "Bad configuration - incoming protected record payload too large."
#endif

#if MBEDTLS_SSL_OUT_PAYLOAD_LEN > MBEDTLS_SSL_MAX_CONTENT_LEN + 2048
#error "Bad configuration - outgoing protected record payload too large."
#endif

/* Calculate buffer sizes */

/* Note: Even though the TLS record header is only 5 bytes
   long, we're internally using 8 bytes to store the
   implicit sequence number. */
#define MBEDTLS_SSL_HEADER_LEN 13

#define MBEDTLS_SSL_IN_BUFFER_LEN  \
    ( ( MBEDTLS_SSL_HEADER_LEN ) + ( MBEDTLS_SSL_IN_PAYLOAD_LEN ) )

#define MBEDTLS_SSL_OUT_BUFFER_LEN  \
    ( ( MBEDTLS_SSL_HEADER_LEN ) + ( MBEDTLS_SSL_OUT_PAYLOAD_LEN ) )

#ifdef MBEDTLS_ZLIB_SUPPORT
/* Compression buffer holds both IN and OUT buffers, so should be size of the larger */
#define MBEDTLS_SSL_COMPRESS_BUFFER_LEN (                               \
        ( MBEDTLS_SSL_IN_BUFFER_LEN > MBEDTLS_SSL_OUT_BUFFER_LEN )      \
        ? MBEDTLS_SSL_IN_BUFFER_LEN                                     \
        : MBEDTLS_SSL_OUT_BUFFER_LEN                                    \
        )
#endif

/*
 * TLS extension flags (for extensions with outgoing ServerHello content
 * that need it (e.g. for RENEGOTIATION_INFO the server already knows because
 * of state of the renegotiation flag, so no indicator is required)
 */
#define MBEDTLS_TLS_EXT_SUPPORTED_POINT_FORMATS_PRESENT (1 << 0)
#define MBEDTLS_TLS_EXT_ECJPAKE_KKPP_OK                 (1 << 1)

#ifdef __cplusplus
extern "C" {
#endif

#if defined(MBEDTLS_SSL_PROTO_TLS1_2) && \
    defined(MBEDTLS_KEY_EXCHANGE__WITH_CERT__ENABLED)
/*
 * Abstraction for a grid of allowed signature-hash-algorithm pairs.
 */
struct mbedtls_ssl_sig_hash_set_t
{
    /* At the moment, we only need to remember a single suitable
     * hash algorithm per signature algorithm. As long as that's
     * the case - and we don't need a general lookup function -
     * we can implement the sig-hash-set as a map from signatures
     * to hash algorithms. */
    mbedtls_md_type_t rsa;
    mbedtls_md_type_t ecdsa;
};
#endif /* MBEDTLS_SSL_PROTO_TLS1_2 &&
          MBEDTLS_KEY_EXCHANGE__WITH_CERT__ENABLED */

/*
 * This structure contains the parameters only needed during handshake.
 */
struct mbedtls_ssl_handshake_params
{
    /*
     * Handshake specific crypto variables
     */

#if defined(MBEDTLS_SSL_PROTO_TLS1_2) && \
    defined(MBEDTLS_KEY_EXCHANGE__WITH_CERT__ENABLED)
    mbedtls_ssl_sig_hash_set_t hash_algs;             
#endif
#if defined(MBEDTLS_DHM_C)
    mbedtls_dhm_context dhm_ctx;                
#endif
#if defined(MBEDTLS_ECDH_C)
    mbedtls_ecdh_context ecdh_ctx;              
#endif
#if defined(MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED)
    mbedtls_ecjpake_context ecjpake_ctx;        
#if defined(MBEDTLS_SSL_CLI_C)
    unsigned char *ecjpake_cache;               
    size_t ecjpake_cache_len;                   
#endif
#endif /* MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED */
#if defined(MBEDTLS_ECDH_C) || defined(MBEDTLS_ECDSA_C) || \
    defined(MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED)
    const mbedtls_ecp_curve_info **curves;      
#endif
#if defined(MBEDTLS_KEY_EXCHANGE__SOME__PSK_ENABLED)
    unsigned char *psk;                 
    size_t psk_len;                     
#endif
#if defined(MBEDTLS_X509_CRT_PARSE_C)
    mbedtls_ssl_key_cert *key_cert;     
#if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION)
    int sni_authmode;                   
    mbedtls_ssl_key_cert *sni_key_cert; 
    mbedtls_x509_crt *sni_ca_chain;     
    mbedtls_x509_crl *sni_ca_crl;       
#endif /* MBEDTLS_SSL_SERVER_NAME_INDICATION */
#endif /* MBEDTLS_X509_CRT_PARSE_C */
#if defined(MBEDTLS_SSL__ECP_RESTARTABLE)
    int ecrs_enabled;                   
    mbedtls_x509_crt_restart_ctx ecrs_ctx;  
    enum { /* this complements ssl->state with info on intra-state operations */
        ssl_ecrs_none = 0,              
        ssl_ecrs_crt_verify,            
        ssl_ecrs_ske_start_processing,  
        ssl_ecrs_cke_ecdh_calc_secret,  
        ssl_ecrs_crt_vrfy_sign,         
    } ecrs_state;                       
    size_t ecrs_n;                      
#endif
#if defined(MBEDTLS_SSL_PROTO_DTLS)
    unsigned int out_msg_seq;           
    unsigned int in_msg_seq;            
    unsigned char *verify_cookie;       
    unsigned char verify_cookie_len;    
    uint32_t retransmit_timeout;        
    unsigned char retransmit_state;     
    mbedtls_ssl_flight_item *flight;    
    mbedtls_ssl_flight_item *cur_msg;   
    unsigned char *cur_msg_p;           
    unsigned int in_flight_start_seq;   
    mbedtls_ssl_transform *alt_transform_out;   
    unsigned char alt_out_ctr[8];       
    struct
    {
        size_t total_bytes_buffered; 
        uint8_t seen_ccs;               
        struct mbedtls_ssl_hs_buffer
        {
            unsigned is_valid      : 1;
            unsigned is_fragmented : 1;
            unsigned is_complete   : 1;
            unsigned char *data;
            size_t data_len;
        } hs[MBEDTLS_SSL_MAX_BUFFERED_HS];

        struct
        {
            unsigned char *data;
            size_t len;
            unsigned epoch;
        } future_record;

    } buffering;

    uint16_t mtu;                       
#endif /* MBEDTLS_SSL_PROTO_DTLS */

    /*
     * Checksum contexts
     */
#if defined(MBEDTLS_SSL_PROTO_SSL3) || defined(MBEDTLS_SSL_PROTO_TLS1) || \
    defined(MBEDTLS_SSL_PROTO_TLS1_1)
       mbedtls_md5_context fin_md5;
      mbedtls_sha1_context fin_sha1;
#endif
#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
#if defined(MBEDTLS_SHA256_C)
    mbedtls_sha256_context fin_sha256;
#endif
#if defined(MBEDTLS_SHA512_C)
    mbedtls_sha512_context fin_sha512;
#endif
#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */

    void (*update_checksum)(mbedtls_ssl_context *, const unsigned char *, size_t);
    void (*calc_verify)(mbedtls_ssl_context *, unsigned char *);
    void (*calc_finished)(mbedtls_ssl_context *, unsigned char *, int);
    int  (*tls_prf)(const unsigned char *, size_t, const char *,
                    const unsigned char *, size_t,
                    unsigned char *, size_t);

    size_t pmslen;                      
    unsigned char randbytes[64];        
    unsigned char premaster[MBEDTLS_PREMASTER_SIZE];
    int resume;                         
    int max_major_ver;                  
    int max_minor_ver;                  
    int cli_exts;                       
#if defined(MBEDTLS_SSL_SESSION_TICKETS)
    int new_session_ticket;             
#endif /* MBEDTLS_SSL_SESSION_TICKETS */
#if defined(MBEDTLS_SSL_EXTENDED_MASTER_SECRET)
    int extended_ms;                    
#endif

#if defined(MBEDTLS_SSL_ASYNC_PRIVATE)
    unsigned int async_in_progress : 1; 
#endif /* MBEDTLS_SSL_ASYNC_PRIVATE */

#if defined(MBEDTLS_SSL_ASYNC_PRIVATE)

    void *user_async_ctx;
#endif /* MBEDTLS_SSL_ASYNC_PRIVATE */
};

typedef struct mbedtls_ssl_hs_buffer mbedtls_ssl_hs_buffer;

/*
 * This structure contains a full set of runtime transform parameters
 * either in negotiation or active.
 */
struct mbedtls_ssl_transform
{
    /*
     * Session specific crypto layer
     */
    const mbedtls_ssl_ciphersuite_t *ciphersuite_info;
    unsigned int keylen;                
    size_t minlen;                      
    size_t ivlen;                       
    size_t fixed_ivlen;                 
    size_t maclen;                      
    unsigned char iv_enc[16];           
    unsigned char iv_dec[16];           
#if defined(MBEDTLS_SSL_PROTO_SSL3)
    /* Needed only for SSL v3.0 secret */
    unsigned char mac_enc[20];          
    unsigned char mac_dec[20];          
#endif /* MBEDTLS_SSL_PROTO_SSL3 */

    mbedtls_md_context_t md_ctx_enc;            
    mbedtls_md_context_t md_ctx_dec;            
    mbedtls_cipher_context_t cipher_ctx_enc;    
    mbedtls_cipher_context_t cipher_ctx_dec;    
    /*
     * Session specific compression layer
     */
#if defined(MBEDTLS_ZLIB_SUPPORT)
    z_stream ctx_deflate;               
    z_stream ctx_inflate;               
#endif
};

#if defined(MBEDTLS_X509_CRT_PARSE_C)
/*
 * List of certificate + private key pairs
 */
struct mbedtls_ssl_key_cert
{
    mbedtls_x509_crt *cert;                 
    mbedtls_pk_context *key;                
    mbedtls_ssl_key_cert *next;             
};
#endif /* MBEDTLS_X509_CRT_PARSE_C */

#if defined(MBEDTLS_SSL_PROTO_DTLS)
/*
 * List of handshake messages kept around for resending
 */
struct mbedtls_ssl_flight_item
{
    unsigned char *p;       
    size_t len;             
    unsigned char type;     
    mbedtls_ssl_flight_item *next;  
};
#endif /* MBEDTLS_SSL_PROTO_DTLS */

#if defined(MBEDTLS_SSL_PROTO_TLS1_2) && \
    defined(MBEDTLS_KEY_EXCHANGE__WITH_CERT__ENABLED)

/* Find an entry in a signature-hash set matching a given hash algorithm. */
mbedtls_md_type_t mbedtls_ssl_sig_hash_set_find( mbedtls_ssl_sig_hash_set_t *set,
                                                 mbedtls_pk_type_t sig_alg );
/* Add a signature-hash-pair to a signature-hash set */
void mbedtls_ssl_sig_hash_set_add( mbedtls_ssl_sig_hash_set_t *set,
                                   mbedtls_pk_type_t sig_alg,
                                   mbedtls_md_type_t md_alg );
/* Allow exactly one hash algorithm for each signature. */
void mbedtls_ssl_sig_hash_set_const_hash( mbedtls_ssl_sig_hash_set_t *set,
                                          mbedtls_md_type_t md_alg );

/* Setup an empty signature-hash set */
static inline void mbedtls_ssl_sig_hash_set_init( mbedtls_ssl_sig_hash_set_t *set )
{
    mbedtls_ssl_sig_hash_set_const_hash( set, MBEDTLS_MD_NONE );
}

#endif /* MBEDTLS_SSL_PROTO_TLS1_2) &&
          MBEDTLS_KEY_EXCHANGE__WITH_CERT__ENABLED */

void mbedtls_ssl_transform_free( mbedtls_ssl_transform *transform );

void mbedtls_ssl_handshake_free( mbedtls_ssl_context *ssl );

int mbedtls_ssl_handshake_client_step( mbedtls_ssl_context *ssl );
int mbedtls_ssl_handshake_server_step( mbedtls_ssl_context *ssl );
void mbedtls_ssl_handshake_wrapup( mbedtls_ssl_context *ssl );

int mbedtls_ssl_send_fatal_handshake_failure( mbedtls_ssl_context *ssl );

void mbedtls_ssl_reset_checksum( mbedtls_ssl_context *ssl );
int mbedtls_ssl_derive_keys( mbedtls_ssl_context *ssl );

int mbedtls_ssl_handle_message_type( mbedtls_ssl_context *ssl );
int mbedtls_ssl_prepare_handshake_record( mbedtls_ssl_context *ssl );
void mbedtls_ssl_update_handshake_status( mbedtls_ssl_context *ssl );

int mbedtls_ssl_read_record( mbedtls_ssl_context *ssl,
                             unsigned update_hs_digest );
int mbedtls_ssl_fetch_input( mbedtls_ssl_context *ssl, size_t nb_want );

int mbedtls_ssl_write_handshake_msg( mbedtls_ssl_context *ssl );
int mbedtls_ssl_write_record( mbedtls_ssl_context *ssl, uint8_t force_flush );
int mbedtls_ssl_flush_output( mbedtls_ssl_context *ssl );

int mbedtls_ssl_parse_certificate( mbedtls_ssl_context *ssl );
int mbedtls_ssl_write_certificate( mbedtls_ssl_context *ssl );

int mbedtls_ssl_parse_change_cipher_spec( mbedtls_ssl_context *ssl );
int mbedtls_ssl_write_change_cipher_spec( mbedtls_ssl_context *ssl );

int mbedtls_ssl_parse_finished( mbedtls_ssl_context *ssl );
int mbedtls_ssl_write_finished( mbedtls_ssl_context *ssl );

void mbedtls_ssl_optimize_checksum( mbedtls_ssl_context *ssl,
                            const mbedtls_ssl_ciphersuite_t *ciphersuite_info );

#if defined(MBEDTLS_KEY_EXCHANGE__SOME__PSK_ENABLED)
int mbedtls_ssl_psk_derive_premaster( mbedtls_ssl_context *ssl, mbedtls_key_exchange_type_t key_ex );
#endif

#if defined(MBEDTLS_PK_C)
unsigned char mbedtls_ssl_sig_from_pk( mbedtls_pk_context *pk );
unsigned char mbedtls_ssl_sig_from_pk_alg( mbedtls_pk_type_t type );
mbedtls_pk_type_t mbedtls_ssl_pk_alg_from_sig( unsigned char sig );
#endif

mbedtls_md_type_t mbedtls_ssl_md_alg_from_hash( unsigned char hash );
unsigned char mbedtls_ssl_hash_from_md_alg( int md );
int mbedtls_ssl_set_calc_verify_md( mbedtls_ssl_context *ssl, int md );

#if defined(MBEDTLS_ECP_C)
int mbedtls_ssl_check_curve( const mbedtls_ssl_context *ssl, mbedtls_ecp_group_id grp_id );
#endif

#if defined(MBEDTLS_KEY_EXCHANGE__WITH_CERT__ENABLED)
int mbedtls_ssl_check_sig_hash( const mbedtls_ssl_context *ssl,
                                mbedtls_md_type_t md );
#endif

#if defined(MBEDTLS_X509_CRT_PARSE_C)
static inline mbedtls_pk_context *mbedtls_ssl_own_key( mbedtls_ssl_context *ssl )
{
    mbedtls_ssl_key_cert *key_cert;

    if( ssl->handshake != NULL && ssl->handshake->key_cert != NULL )
        key_cert = ssl->handshake->key_cert;
    else
        key_cert = ssl->conf->key_cert;

    return( key_cert == NULL ? NULL : key_cert->key );
}

static inline mbedtls_x509_crt *mbedtls_ssl_own_cert( mbedtls_ssl_context *ssl )
{
    mbedtls_ssl_key_cert *key_cert;

    if( ssl->handshake != NULL && ssl->handshake->key_cert != NULL )
        key_cert = ssl->handshake->key_cert;
    else
        key_cert = ssl->conf->key_cert;

    return( key_cert == NULL ? NULL : key_cert->cert );
}

/*
 * Check usage of a certificate wrt extensions:
 * keyUsage, extendedKeyUsage (later), and nSCertType (later).
 *
 * Warning: cert_endpoint is the endpoint of the cert (ie, of our peer when we
 * check a cert we received from them)!
 *
 * Return 0 if everything is OK, -1 if not.
 */
int mbedtls_ssl_check_cert_usage( const mbedtls_x509_crt *cert,
                          const mbedtls_ssl_ciphersuite_t *ciphersuite,
                          int cert_endpoint,
                          uint32_t *flags );
#endif /* MBEDTLS_X509_CRT_PARSE_C */

void mbedtls_ssl_write_version( int major, int minor, int transport,
                        unsigned char ver[2] );
void mbedtls_ssl_read_version( int *major, int *minor, int transport,
                       const unsigned char ver[2] );

static inline size_t mbedtls_ssl_hdr_len( const mbedtls_ssl_context *ssl )
{
#if defined(MBEDTLS_SSL_PROTO_DTLS)
    if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
        return( 13 );
#else
    ((void) ssl);
#endif
    return( 5 );
}

static inline size_t mbedtls_ssl_hs_hdr_len( const mbedtls_ssl_context *ssl )
{
#if defined(MBEDTLS_SSL_PROTO_DTLS)
    if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
        return( 12 );
#else
    ((void) ssl);
#endif
    return( 4 );
}

#if defined(MBEDTLS_SSL_PROTO_DTLS)
void mbedtls_ssl_send_flight_completed( mbedtls_ssl_context *ssl );
void mbedtls_ssl_recv_flight_completed( mbedtls_ssl_context *ssl );
int mbedtls_ssl_resend( mbedtls_ssl_context *ssl );
int mbedtls_ssl_flight_transmit( mbedtls_ssl_context *ssl );
#endif

/* Visible for testing purposes only */
#if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY)
int mbedtls_ssl_dtls_replay_check( mbedtls_ssl_context *ssl );
void mbedtls_ssl_dtls_replay_update( mbedtls_ssl_context *ssl );
#endif

/* constant-time buffer comparison */
static inline int mbedtls_ssl_safer_memcmp( const void *a, const void *b, size_t n )
{
    size_t i;
    volatile const unsigned char *A = (volatile const unsigned char *) a;
    volatile const unsigned char *B = (volatile const unsigned char *) b;
    volatile unsigned char diff = 0;

    for( i = 0; i < n; i++ )
    {
        /* Read volatile data in order before computing diff.
         * This avoids IAR compiler warning:
         * 'the order of volatile accesses is undefined ..' */
        unsigned char x = A[i], y = B[i];
        diff |= x ^ y;
    }

    return( diff );
}

#if defined(MBEDTLS_SSL_PROTO_SSL3) || defined(MBEDTLS_SSL_PROTO_TLS1) || \
    defined(MBEDTLS_SSL_PROTO_TLS1_1)
int mbedtls_ssl_get_key_exchange_md_ssl_tls( mbedtls_ssl_context *ssl,
                                        unsigned char *output,
                                        unsigned char *data, size_t data_len );
#endif /* MBEDTLS_SSL_PROTO_SSL3 || MBEDTLS_SSL_PROTO_TLS1 || \
          MBEDTLS_SSL_PROTO_TLS1_1 */

#if defined(MBEDTLS_SSL_PROTO_TLS1) || defined(MBEDTLS_SSL_PROTO_TLS1_1) || \
    defined(MBEDTLS_SSL_PROTO_TLS1_2)
int mbedtls_ssl_get_key_exchange_md_tls1_2( mbedtls_ssl_context *ssl,
                                            unsigned char *hash, size_t *hashlen,
                                            unsigned char *data, size_t data_len,
                                            mbedtls_md_type_t md_alg );
#endif /* MBEDTLS_SSL_PROTO_TLS1 || MBEDTLS_SSL_PROTO_TLS1_1 || \
          MBEDTLS_SSL_PROTO_TLS1_2 */

#ifdef __cplusplus
}
#endif

#endif /* ssl_internal.h */