Qt中调用PolarSSL库(一)

     最近一直在学习SSL相关的知识，也是先了解理论相关的知识，主要是SSL相关的基本概念和连接建立过程，主要是基于PolarSSL开源库进行学习。学习完了之后就希望能给有所运用，就想用Qt写一个简单的程序，增加对SSL相关概念的把握和对PolarSSL库的运用。当然，最终希望是可以使用Qt做一个比较完善的工具，帮助大家更好的理解和学习SSL相关知识。这都是后话，在第一篇里面，我们就简单用例子展示如何在Qt里面调用PolarSSL库。

这篇博客主要是讲解Qt里面调用PolarSSL库，至于SSL相关概念在后面的博客再详细介绍。

SSL握手需要客户端和服务器端交互，这里我们分别介绍。

1、编译PolarSSL库

我们准备使用的方式就是编译PolarSSL为.a静态库，然后在Qt中连接，使用的PolarSSL的版本是0.10.1。

下载对应的软件版本，解压缩后在library目录下执行make即可生成libpolarssl.a库文件，如下图：

2、服务器端

使用Qt设计一个简单的界面，在按钮的槽函数中进行相关的操作，也就是调用PolarSSL库函数进行编程，初始化ssl相关结构体，监听端口，等等。

SSL中最重要的就是执行握手操作。这里需要注意一点，由于涉及到socket编程，像accept函数都是阻塞的，如果在gui主线程中调用会造成界面冻结，也就是我们常说的ANR。解决方法就是将这些操作放在一个线程中，Qt中创建一个线程比较容易，创建一个类，继承自QThread，实现run函数，即可，最后启动线程也比较简单，调用该类的start()

函数即可。好了，不多说了，上代码，首先看看服务器端的代码结构：workThread即是线程，实现SSL相关的功能，监听套接字，实现SSL握手，读取客户端发来的消息，向客户端发送消息。

mianwindow即是主窗口界面，有个按钮，在按钮的槽函数中启动线程

代码：

工程文件：

#-------------------------------------------------
#
# Project created by QtCreator 2014-05-11T22:28:07
#
#-------------------------------------------------

QT       += core gui

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = MyPolarSSLToolSrv
TEMPLATE = app

INCLUDEPATH += /home/chenlong12580/develop/polarTool/polarssl/include
LIBS += -L "/home/chenlong12580/develop/polarTool/polarssl/lib/" -lpolarssl

SOURCES += main.cpp
        widget.cpp
    workthread.cpp

HEADERS  += widget.h
    workthread.h

FORMS    += widget.ui

线程类：

void WorkThread::run()
{
    qDebug() << "I am a thread!";

    int listen_fd = 0;
    int client_fd =0;
    int ret= 0;
    havege_state hs;
    ssl_context ssl;
    ssl_session ssn;
    x509_cert srvcert;
    rsa_context rsa;
    unsigned char buf[1024];
    int len = 0;

    memset( &srvcert, 0, sizeof( x509_cert ) );

    ret = x509parse_crt( &srvcert, (unsigned char *) test_srv_crt,
                         strlen( test_srv_crt ) );
    if( ret != 0 )
    {
        printf( " failed
  !  x509parse_crt returned %d

", ret );
        return;
    }

    ret = x509parse_crt( &srvcert, (unsigned char *) test_ca_crt,
                         strlen( test_ca_crt ) );
    if( ret != 0 )
    {
        printf( " failed
  !  x509parse_crt returned %d

", ret );
        return;
    }

    ret =  x509parse_key( &rsa, (unsigned char *) test_srv_key,
                          strlen( test_srv_key ), NULL, 0 );
    if( ret != 0 )
    {
        printf( " failed
  !  x509parse_key returned %d

", ret );
        return;
    }

    ret = net_bind( &listen_fd, NULL, 8443 );
    if (0 != ret)
    {
        qDebug() << ret;
        return;
    }

    qDebug() << "bind ok";

    /* socket is block */
    ret = net_accept( listen_fd, &client_fd, NULL );
    if (0 != ret)
    {
        return;
    }

    qDebug() << "accept ok";

    havege_init( &hs );

    ret = ssl_init( &ssl );
    if (0 != ret)
    {
        return;
    }

    ssl_set_endpoint( &ssl, SSL_IS_SERVER );
    ssl_set_authmode( &ssl, SSL_VERIFY_NONE );

    ssl_set_rng( &ssl, havege_rand, &hs );
    ssl_set_dbg( &ssl, my_debug, stdout );
    ssl_set_bio( &ssl, net_recv, &client_fd,
                 net_send, &client_fd );
    ssl_set_scb( &ssl, my_get_session,
                 my_set_session );

    ssl_set_ciphers( &ssl, my_ciphers );
    ssl_set_session( &ssl, 1, 0, &ssn );

    memset( &ssn, 0, sizeof( ssl_session ) );

    ssl_set_ca_chain( &ssl, srvcert.next, NULL );
    ssl_set_own_cert( &ssl, &srvcert, &rsa );
    ssl_set_dh_param( &ssl, my_dhm_P, my_dhm_G );

    qDebug() << "before ssl_handshake ok";

    while( ( ret = ssl_handshake( &ssl ) ) != 0 )
    {
        ;
    }

    qDebug() << "ssl_handshake ok";

    do
    {
        len = sizeof( buf ) - 1;
        memset( buf, 0, sizeof( buf ) );
        ret = ssl_read( &ssl, buf, len );

        if( ret == POLARSSL_ERR_NET_TRY_AGAIN )
            continue;

        if( ret <= 0 )
        {
            switch( ret )
            {
            case POLARSSL_ERR_SSL_PEER_CLOSE_NOTIFY:
                printf( " connection was closed gracefully
" );
                break;

            case POLARSSL_ERR_NET_CONN_RESET:
                printf( " connection was reset by peer
" );
                break;

            default:
                printf( " ssl_read returned %d
", ret );
                break;
            }

            break;
        }

        len = ret;
        printf( " %d bytes read

%s", len, (char *) buf );
    }while( 0 );

    char *cc = (char *)buf;
    QString ss(cc);

    qDebug() << ss;

    (void)sprintf( (char *) buf, HTTP_RESPONSE,
                       ssl_get_cipher( &ssl ) );

    while( ( ret = ssl_write( &ssl, buf, len ) ) <= 0 )
    {
        if( ret == POLARSSL_ERR_NET_CONN_RESET )
        {
            printf( " failed
  ! peer closed the connection

" );
            return;
        }

        if( ret != POLARSSL_ERR_NET_TRY_AGAIN )
        {
            printf( " failed
  ! ssl_write returned %d

", ret );
            return;
        }
    }

    ssl_close_notify( &ssl );

    net_close( client_fd );
    x509_free( &srvcert );
    rsa_free( &rsa );
    ssl_free( &ssl );

    cur = s_list_1st;
    while( cur != NULL )
    {
        prv = cur;
        cur = cur->next;
        memset( prv, 0, sizeof( ssl_session ) );
        free( prv );
    }

    memset( &ssl, 0, sizeof( ssl_context ) );
}

主窗口类：

#include "widget.h"
#include "ui_widget.h"
#include <QFileDialog>
#include <QDebug>
#include <QMessageBox>
#include "workthread.h"
#include "polarssl/havege.h"
#include "polarssl/certs.h"
#include "polarssl/x509.h"
#include "polarssl/ssl.h"
#include "polarssl/net.h"

Widget::Widget(QWidget *parent) :
    QWidget(parent),
    ui(new Ui::Widget)
{
    ui->setupUi(this);

    qDebug() << "server";

    connect(this, SIGNAL(emit_parse_cer()), this, SLOT(slot_parse_cer()));
}

Widget::~Widget()
{
    delete ui;
}

void Widget::on_BrowseBtn_clicked()
{
    QString pathStr = QFileDialog::getOpenFileName(this, QString("选择证书文件"), QString("C:\Users\Administrator\Desktop"), QString("*.*"));
    if (pathStr.length() == 0)
    {
        qDebug() << "please select a cer file!";
        return;
    }

    ui->PathEdit->setText(pathStr);

    emit emit_parse_cer();
}

void Widget::slot_parse_cer()
{
    x509_cert crt;
    memset(&crt, 0, sizeof(crt));

    int res = x509parse_crtfile( &crt, ui->PathEdit->text().toLatin1().data());
    if (0 != res)
    {
        QMessageBox::warning(this, "警告", "解析证书失败，请选择正确的证书文件", QMessageBox::Ok);
        return;
    }

    ui->CrtInfo->setText(QString("是否为根证书：") + QString::number(crt.ca_istrue));
    ui->CrtInfo->append(QString("证书版本号：") + QString::number(crt.version));
    ui->CrtInfo->append(QString("有效期：") + QString::number(crt.valid_from.year) + "-" + QString::number(crt.valid_from.mon)
    + QString("  到：") + QString::number(crt.valid_to.year) + "-" + QString::number(crt.valid_to.mon));

    qDebug() << crt.ca_istrue;
    qDebug() << crt.valid_from.year;
}

void Widget::on_pushButton_clicked()
{
    WorkThread *workThread = new WorkThread;
    workThread->start();
}

3、客户端

客户端比较简单，直接在界面类进行的SSL功能相关的实现，就是创建套接字，链接服务器，进行SSL握手，向服务器发消息，读取服务器发来的消息。

工程文件：

#-------------------------------------------------
#
# Project created by QtCreator 2014-05-11T22:28:07
#
#-------------------------------------------------

QT       += core gui

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = MyPolarSSLToolCli
TEMPLATE = app

INCLUDEPATH += /home/chenlong12580/develop/polarTool/polarssl/include
LIBS += -L "/home/chenlong12580/develop/polarTool/polarssl/lib/" -lpolarssl

SOURCES += main.cpp
        widget.cpp

HEADERS  += widget.h

FORMS    += widget.ui

主窗口类：

#include "widget.h"
#include "ui_widget.h"
#include <QFileDialog>
#include <QDebug>
#include <QMessageBox>
#include "polarssl/havege.h"
#include "polarssl/certs.h"
#include "polarssl/x509.h"
#include "polarssl/ssl.h"
#include "polarssl/net.h"

#define SERVER_PORT 8443
/*
#define SERVER_NAME "localhost"
#define GET_REQUEST "GET / HTTP/1.0

"
*/
#define SERVER_NAME "polarssl.org"
#define GET_REQUEST
    "GET /hello/ HTTP/1.1
"
    "Host: polarssl.org

"

#define DEBUG_LEVEL 0

void my_debug( void *ctx, int level, char *str )
{
    if( level < DEBUG_LEVEL )
    {
        fprintf( (FILE *) ctx, "%s", str );
        fflush(  (FILE *) ctx  );
    }
}

Widget::Widget(QWidget *parent) :
    QWidget(parent),
    ui(new Ui::Widget)
{
    ui->setupUi(this);

    qDebug() << "client";

    connect(this, SIGNAL(emit_parse_cer()), this, SLOT(slot_parse_cer()));
}

Widget::~Widget()
{
    delete ui;
}

void Widget::on_BrowseBtn_clicked()
{
    QString pathStr = QFileDialog::getOpenFileName(this, QString("选择证书文件"), QString("C:\Users\Administrator\Desktop"), QString("*.*"));
    if (pathStr.length() == 0)
    {
        qDebug() << "please select a cer file!";
        return;
    }

    ui->PathEdit->setText(pathStr);

    emit emit_parse_cer();
}

void Widget::slot_parse_cer()
{
    x509_cert crt;
    memset(&crt, 0, sizeof(crt));

    int res = x509parse_crtfile( &crt, ui->PathEdit->text().toLatin1().data());
    if (0 != res)
    {
        QMessageBox::warning(this, "警告", "解析证书失败，请选择正确的证书文件", QMessageBox::Ok);
        return;
    }

    ui->CrtInfo->setText(QString("是否为根证书：") + QString::number(crt.ca_istrue));
    ui->CrtInfo->append(QString("证书版本号：") + QString::number(crt.version));
    ui->CrtInfo->append(QString("有效期：") + QString::number(crt.valid_from.year) + "-" + QString::number(crt.valid_from.mon)
    + QString("  到：") + QString::number(crt.valid_to.year) + "-" + QString::number(crt.valid_to.mon));

    qDebug() << crt.ca_istrue;
    qDebug() << crt.valid_from.year;
}

void Widget::on_pushButton_clicked()
{
    int ret, len, server_fd;
    unsigned char buf[1024];
    havege_state hs;
    ssl_context ssl;
    ssl_session ssn;

    /*
         * 0. Initialize the RNG and the session data
         */
    havege_init( &hs );
    memset( &ssn, 0, sizeof( ssl_session ) );

    /*
         * 1. Start the connection
         */
    printf( "
  . Connecting to tcp/%s/%4d...", SERVER_NAME,
            SERVER_PORT );
    fflush( stdout );

    if( ( ret = net_connect( &server_fd, "127.0.0.1",
                             SERVER_PORT ) ) != 0 )
    {
        printf( " failed
  ! net_connect returned %d

", ret );
        return;
    }

    printf( " ok
" );

    /*
         * 2. Setup stuff
         */
    printf( "  . Setting up the SSL/TLS structure..." );
    fflush( stdout );

    if( ( ret = ssl_init( &ssl ) ) != 0 )
    {
        printf( " failed
  ! ssl_init returned %d

", ret );
        return;
    }

    printf( " ok
" );

    ssl_set_endpoint( &ssl, SSL_IS_CLIENT );
    ssl_set_authmode( &ssl, SSL_VERIFY_NONE );

    ssl_set_rng( &ssl, havege_rand, &hs );
    ssl_set_dbg( &ssl, my_debug, stdout );
    ssl_set_bio( &ssl, net_recv, &server_fd,
                 net_send, &server_fd );

    ssl_set_ciphers( &ssl, ssl_default_ciphers );
    ssl_set_session( &ssl, 1, 600, &ssn );

    /*
         * 3. Write the GET request
         */
    printf( "  > Write to server:" );
    fflush( stdout );

    len = sprintf( (char *) buf, GET_REQUEST );

    while( ( ret = ssl_write( &ssl, buf, len ) ) <= 0 )
    {
        if( ret != POLARSSL_ERR_NET_TRY_AGAIN )
        {
            printf( " failed
  ! ssl_write returned %d

", ret );
            return;
        }
    }

    len = ret;
    printf( " %d bytes written

%s", len, (char *) buf );

    /*
         * 7. Read the HTTP response
         */
    printf( "  < Read from server:" );
    fflush( stdout );

    do
    {
        len = sizeof( buf ) - 1;
        memset( buf, 0, sizeof( buf ) );
        ret = ssl_read( &ssl, buf, len );

        if( ret == POLARSSL_ERR_NET_TRY_AGAIN )
            continue;

        if( ret == POLARSSL_ERR_SSL_PEER_CLOSE_NOTIFY )
            break;

        if( ret <= 0 )
        {
            printf( "failed
  ! ssl_read returned %d

", ret );
            break;
        }

        len = ret;
        printf( " %d bytes read

%s", len, (char *) buf );
    }
    while( 0 );

   char *cc= (char *)buf;
   QString ss(cc);

    qDebug() << ss;

    ssl_close_notify( &ssl );

    return;
}

4、运行效果

下面说说运行的效果，首先启动服务器端，服务器端启动线程，监听套接字：

接着启动客户端，客户端链接服务器端，写入消息，读取服务器端的响应：

最后根据打印可以看出服务器端和客户端握手成功，写入读取消息成功：

我们可以根据抓包来看看SSL握手的过程，如下：

通过抓包可以看到服务器端和客户端的握手过程，以及在不同的握手阶段中做得事情：

服务器端：

/*
 * SSL handshake -- server side
 */
int ssl_handshake_server( ssl_context *ssl )
{
    int ret = 0;

    SSL_DEBUG_MSG( 2, ( "=> handshake server" ) );

    while( ssl->state != SSL_HANDSHAKE_OVER )
    {
        SSL_DEBUG_MSG( 2, ( "server state: %d", ssl->state ) );

        if( ( ret = ssl_flush_output( ssl ) ) != 0 )
            break;

        switch( ssl->state )
        {
            case SSL_HELLO_REQUEST:
                ssl->state = SSL_CLIENT_HELLO;
                break;

            /*
             *  <==   ClientHello
             */
            case SSL_CLIENT_HELLO:
                ret = ssl_parse_client_hello( ssl );
                break;

            /*
             *  ==>   ServerHello
             *        Certificate
             *      ( ServerKeyExchange  )
             *      ( CertificateRequest )
             *        ServerHelloDone
             */
            case SSL_SERVER_HELLO:
                ret = ssl_write_server_hello( ssl );
                break;

            case SSL_SERVER_CERTIFICATE:
                ret = ssl_write_certificate( ssl );
                break;

            case SSL_SERVER_KEY_EXCHANGE:
                ret = ssl_write_server_key_exchange( ssl );
                break;

            case SSL_CERTIFICATE_REQUEST:
                ret = ssl_write_certificate_request( ssl );
                break;

            case SSL_SERVER_HELLO_DONE:
                ret = ssl_write_server_hello_done( ssl );
                break;

            /*
             *  <== ( Certificate/Alert  )
             *        ClientKeyExchange
             *      ( CertificateVerify  )
             *        ChangeCipherSpec
             *        Finished
             */
            case SSL_CLIENT_CERTIFICATE:
                ret = ssl_parse_certificate( ssl );
                break;

            case SSL_CLIENT_KEY_EXCHANGE:
                ret = ssl_parse_client_key_exchange( ssl );
                break;

            case SSL_CERTIFICATE_VERIFY:
                ret = ssl_parse_certificate_verify( ssl );
                break;

            case SSL_CLIENT_CHANGE_CIPHER_SPEC:
                ret = ssl_parse_change_cipher_spec( ssl );
                break;

            case SSL_CLIENT_FINISHED:
                ret = ssl_parse_finished( ssl );
                break;

            /*
             *  ==>   ChangeCipherSpec
             *        Finished
             */
            case SSL_SERVER_CHANGE_CIPHER_SPEC:
                ret = ssl_write_change_cipher_spec( ssl );
                break;

            case SSL_SERVER_FINISHED:
                ret = ssl_write_finished( ssl );
                break;

            case SSL_FLUSH_BUFFERS:
                SSL_DEBUG_MSG( 2, ( "handshake: done" ) );
                ssl->state = SSL_HANDSHAKE_OVER;
                break;

            default:
                SSL_DEBUG_MSG( 1, ( "invalid state %d", ssl->state ) );
                return( POLARSSL_ERR_SSL_BAD_INPUT_DATA );
        }

        if( ret != 0 )
            break;
    }

    SSL_DEBUG_MSG( 2, ( "<= handshake server" ) );

    return( ret );
}

客户端：

/*
 * SSL handshake -- client side
 */
int ssl_handshake_client( ssl_context *ssl )
{
    int ret = 0;

    SSL_DEBUG_MSG( 2, ( "=> handshake client" ) );

    while( ssl->state != SSL_HANDSHAKE_OVER )
    {
        SSL_DEBUG_MSG( 2, ( "client state: %d", ssl->state ) );

        if( ( ret = ssl_flush_output( ssl ) ) != 0 )
            break;

        switch( ssl->state )
        {
            case SSL_HELLO_REQUEST:
                ssl->state = SSL_CLIENT_HELLO;
                break;

            /*
             *  ==>   ClientHello
             */
            case SSL_CLIENT_HELLO:
                ret = ssl_write_client_hello( ssl );
                break;

            /*
             *  <==   ServerHello
             *        Certificate
             *      ( ServerKeyExchange  )
             *      ( CertificateRequest )
             *        ServerHelloDone
             */
            case SSL_SERVER_HELLO:
                ret = ssl_parse_server_hello( ssl );
                break;

            case SSL_SERVER_CERTIFICATE:
                ret = ssl_parse_certificate( ssl );
                break;

            case SSL_SERVER_KEY_EXCHANGE:
                ret = ssl_parse_server_key_exchange( ssl );
                break;

            case SSL_CERTIFICATE_REQUEST:
                ret = ssl_parse_certificate_request( ssl );
                break;

            case SSL_SERVER_HELLO_DONE:
                ret = ssl_parse_server_hello_done( ssl );
                break;

            /*
             *  ==> ( Certificate/Alert  )
             *        ClientKeyExchange
             *      ( CertificateVerify  )
             *        ChangeCipherSpec
             *        Finished
             */
            case SSL_CLIENT_CERTIFICATE:
                ret = ssl_write_certificate( ssl );
                break;

            case SSL_CLIENT_KEY_EXCHANGE:
                ret = ssl_write_client_key_exchange( ssl );
                break;

            case SSL_CERTIFICATE_VERIFY:
                ret = ssl_write_certificate_verify( ssl );
                break;

            case SSL_CLIENT_CHANGE_CIPHER_SPEC:
                ret = ssl_write_change_cipher_spec( ssl );
                break;

            case SSL_CLIENT_FINISHED:
                ret = ssl_write_finished( ssl );
                break;

            /*
             *  <==   ChangeCipherSpec
             *        Finished
             */
            case SSL_SERVER_CHANGE_CIPHER_SPEC:
                ret = ssl_parse_change_cipher_spec( ssl );
                break;

            case SSL_SERVER_FINISHED:
                ret = ssl_parse_finished( ssl );
                break;

            case SSL_FLUSH_BUFFERS:
                SSL_DEBUG_MSG( 2, ( "handshake: done" ) );
                ssl->state = SSL_HANDSHAKE_OVER;
                break;

            default:
                SSL_DEBUG_MSG( 1, ( "invalid state %d", ssl->state ) );
                return( POLARSSL_ERR_SSL_BAD_INPUT_DATA );
        }

        if( ret != 0 )
            break;
    }

    SSL_DEBUG_MSG( 2, ( "<= handshake client" ) );

    return( ret );
}