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：

Qt中调用PolarSSL库(一)

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\n ! x509parse_crt returned %d\n\n", ret );
return;
}
ret = x509parse_crt( &srvcert, (unsigned char *) test_ca_crt,
strlen( test_ca_crt ) );
if( ret != 0 )
{
printf( " failed\n ! x509parse_crt returned %d\n\n", ret );
return;
}
ret = x509parse_key( &rsa, (unsigned char *) test_srv_key,
strlen( test_srv_key ), NULL, 0 );
if( ret != 0 )
{
printf( " failed\n ! x509parse_key returned %d\n\n", 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\n" );
break;
case POLARSSL_ERR_NET_CONN_RESET:
printf( " connection was reset by peer\n" );
break;
default:
printf( " ssl_read returned %d\n", ret );
break;
}
break;
}
len = ret;
printf( " %d bytes read\n\n%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\n ! peer closed the connection\n\n" );
return;
}
if( ret != POLARSSL_ERR_NET_TRY_AGAIN )
{
printf( " failed\n ! ssl_write returned %d\n\n", 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\r\n\r\n"
*/
#define SERVER_NAME "polarssl.org"
#define GET_REQUEST \
"GET /hello/ HTTP/1.1\r\n" \
"Host: polarssl.org\r\n\r\n"
#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( "\n . 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\n ! net_connect returned %d\n\n", ret );
return;
}
printf( " ok\n" );
/*
* 2. Setup stuff
*/
printf( " . Setting up the SSL/TLS structure..." );
fflush( stdout );
if( ( ret = ssl_init( &ssl ) ) != 0 )
{
printf( " failed\n ! ssl_init returned %d\n\n", ret );
return;
}
printf( " ok\n" );
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\n ! ssl_write returned %d\n\n", ret );
return;
}
}
len = ret;
printf( " %d bytes written\n\n%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\n ! ssl_read returned %d\n\n", ret );
break;
}
len = ret;
printf( " %d bytes read\n\n%s", len, (char *) buf );
}
while( 0 );
char *cc= (char *)buf;
QString ss(cc);
qDebug() << ss;
ssl_close_notify( &ssl );
return;
}