数据处理思想和程序架构: 使用Mbedtls包中的SSL,和服务器进行网络加密通信

/*假设接收网络数据函数*/
int net_recv(char *data);
/*假设TCP发送数据函数*/
int net_send(char *data,int len);

/*随机数函数*/
int mbedtls_hardware_poll( void *data,
                    unsigned char *output, size_t len, size_t *olen )
{
    unsigned long randomValue = ((rand()*20) + 1000);//生成随机数
    ((void) data);
    *olen = 0;
    
    if( len < sizeof(unsigned long) ) return( 0 );    

    memcpy( output, &randomValue, sizeof(unsigned long) );
    *olen = sizeof(unsigned long);
  return 0;
}

/**
* @brief  时间函数(SSL底层会调用时间验证证书是否过期)
**/
//struct tm *lcTime;
//time_t startTime;
//    lcTime = localtime (&startTime);
_ARMABI time_t time(time_t *t)
{
//    time_t it;
    if (t) {
        return *t;
    }
    else
    {
//        startTime = 0;
//        lcTime = localtime (&startTime);
//        it = mktime(lcTime);
//        return it ;
        return 0;
    }
}

/**
* @brief  自定义接收函数(把自己的接收函数放到此函数中)
* @param  None
* @param  None
* @param  None
* @retval None
* @example 
**/
int net_recv_data_len=0; 
int net_recv_data_len_count=0;
char net_recv_buff[2000];
static int custom_ssl_recv( void *ctx, unsigned char *buf, size_t len )
{
    int rbCanReadLen;
    
    if(net_recv_data_len ==0)
    {
        net_recv_data_len=net_recv(net_recv_buff);//调用自己的函数接收数据
        if(net_recv_data_len>0)//有数据
        {
            if(len >= net_recv_data_len)//希望读取的数据个数大于实际的数据个数
            {
                len = net_recv_data_len;
                memcpy(buf, net_recv_buff, len);
                
                net_recv_data_len = 0;
                net_recv_data_len_count=0;
                return len;
            }
            else//实际的数据个数比希望读取的多
            {
                memcpy(buf, net_recv_buff, len);
                net_recv_data_len_count = len;
                return len;
            }
        }
        else
        {
            return MBEDTLS_ERR_NET_RECV_FAILED;
        }
    }
    else
    {
        if(len >= net_recv_data_len - net_recv_data_len_count)//希望读取的数据个数大于实际的数据个数
        {
            len = net_recv_data_len - net_recv_data_len_count;
            memcpy(buf, net_recv_buff+net_recv_data_len_count, len);
            net_recv_data_len = 0;
            net_recv_data_len_count=0;
            return len;
        }
        else//实际的数据个数比希望读取的多
        {
            memcpy(buf, net_recv_buff + net_recv_data_len_count, len);
            net_recv_data_len_count = net_recv_data_len_count + len;
            return len;
        }
    }
}

/*增加发送函数*/
static int custom_ssl_send( void *ctx, unsigned char *buf, size_t len )
{
    ctx = ctx;
    net_send(buf,len);//调用自己的TCP发送函数
    return (int)len;
}

int ret;//
const char *pers = "ssl_client1";
mbedtls_entropy_context entropy;
mbedtls_ctr_drbg_context ctr_drbg;
mbedtls_ssl_context ssl;
mbedtls_ssl_config conf;


void ssl_int(void)
{
    mbedtls_ssl_close_notify( &ssl );
    mbedtls_ssl_free( &ssl );
    mbedtls_ssl_config_free( &conf );
    mbedtls_ctr_drbg_free( &ctr_drbg );
    mbedtls_entropy_free( &entropy );
    
    //    mbedtls_debug_set_threshold( 1 );//
    mbedtls_ssl_init( &ssl );
    mbedtls_ssl_config_init( &conf );
    mbedtls_ctr_drbg_init( &ctr_drbg );
    mbedtls_entropy_init( &entropy );

    printf( "\n  . Seeding the random number generator..." );
    //DRBG---->Deterministic Random Bit Generators 伪随机数产生器
    if( ( ret = mbedtls_ctr_drbg_seed( &ctr_drbg, mbedtls_entropy_func, &entropy,
                                                         (const unsigned char *) pers,
                                                         strlen( pers ) ) ) != 0 )
    {
            printf( " failed\n  ! mbedtls_ctr_drbg_seed returned %d\n", ret );
    }
    
    
    //MBEDTLS_SSL_IS_CLIENT 表示配置为客户端
    //MBEDTLS_SSL_TRANSPORT_STREAM 表示传输方式为TLS
    //设置版本， MBEDTLS_SSL_PRESET_DEFAULT 表示 TLS1.0
    if( ( ret = mbedtls_ssl_config_defaults( &conf,
                                    MBEDTLS_SSL_IS_CLIENT,
                                    MBEDTLS_SSL_TRANSPORT_STREAM,
                                    MBEDTLS_SSL_PRESET_DEFAULT ) ) != 0 )
    {
            printf( " failed\n  ! mbedtls_ssl_config_defaults returned %d\r\n", ret );
    }
 
 
    /*设置数字证书检查模式 
    *  MBEDTLS_SSL_VERIFY_NONE:      peer certificate is not checked
    *                        (default on server)
    *                        (insecure on client)
    *
    *  MBEDTLS_SSL_VERIFY_OPTIONAL:  peer certificate is checked, however the
    *                        handshake continues even if verification failed;
    *                        mbedtls_ssl_get_verify_result() can be called after the
    *                        handshake is complete.
    *
    *  MBEDTLS_SSL_VERIFY_REQUIRED:  peer *must* present a valid certificate,
    *                        handshake is aborted if verification failed.
    *                        (default on client)
    */
    mbedtls_ssl_conf_authmode( &conf, MBEDTLS_SSL_VERIFY_NONE );
    // 配置随机数生成器的回调函数
    mbedtls_ssl_conf_rng( &conf, mbedtls_ctr_drbg_random, &ctr_drbg );
    // 配置调试回调函数
    //    mbedtls_ssl_conf_dbg( &conf, my_debug, stdout );
    
    // 根据conf设置ssl结构
    if( ( ret = mbedtls_ssl_setup( &ssl, &conf ) ) != 0 )
    {
            mbedtls_printf( " failed\n  ! mbedtls_ssl_setup returned 0x%x\r\n", -ret );
    }

    // 设置host name 用到动态内存分配
    if( ( ret = mbedtls_ssl_set_hostname( &ssl, "替换自己的域名" ) ) != 0 )
    {
            mbedtls_printf( " failed\n  ! mbedtls_ssl_set_hostname returned %d\r\n", ret );
    }
    // 设置发送和接收接口
    mbedtls_ssl_set_bio( &ssl, NULL, custom_ssl_send, custom_ssl_recv, NULL );
}

/*设置 debug 输出函数*/
static void my_debug( void *ctx, int level,
                      const char *file, int line, const char *str )
{
    printf("%s:%04d: %s\r\n", file, line, str );
}