libevent添加ssl加密功能

libevent的ssl加密功能

继前面两篇博文：
openssl编程之客户端
http://blog.csdn.net/fly2010love/article/details/46458805
openssl编程之服务端
http://blog.csdn.net/fly2010love/article/details/46458963
此篇博文主要介绍如何在libevent中使用openssl集成
关于libevent的使用方法，请自己百度或关注后续博文
程序如下：

#include <netinet/in.h>#include <sys/socket.h>#include <fcntl.h>#include <event2/event.h>#include <event2/buffer.h>#include <event2/bufferevent.h>#include <event2/bufferevent_ssl.h>#include <openssl/err.h>#include <openssl/ssl.h>#include <assert.h>#include <unistd.h>#include <string.h>#include <stdlib.h>#include <stdio.h>#include <errno.h>#define CA_CERT_FILE "server/ca.crt"#define SERVER_CERT_FILE "server/server.crt"#define SERVER_KEY_FILE "server/server.key"SSL* CreateSSL(evutil_socket_t& fd){    SSL_CTX* ctx = NULL;      SSL* ssl = NULL;     ctx = SSL_CTX_new (SSLv23_method());    if( ctx == NULL)    {        printf("SSL_CTX_new error!\n");        return NULL;    }    // 要求校验对方证书      SSL_CTX_set_verify(ctx, SSL_VERIFY_PEER, NULL);      // 加载CA的证书      if(!SSL_CTX_load_verify_locations(ctx, CA_CERT_FILE, NULL))    {        printf("SSL_CTX_load_verify_locations error!\n");        return NULL;    }    // 加载自己的证书      if(SSL_CTX_use_certificate_file(ctx, SERVER_CERT_FILE, SSL_FILETYPE_PEM) <= 0)    {        printf("SSL_CTX_use_certificate_file error!\n");        return NULL;    }    // 加载自己的私钥      if(SSL_CTX_use_PrivateKey_file(ctx, SERVER_KEY_FILE, SSL_FILETYPE_PEM) <= 0)    {        printf("SSL_CTX_use_PrivateKey_file error!\n");        return NULL;    }    // 判定私钥是否正确      if(!SSL_CTX_check_private_key(ctx))    {        printf("SSL_CTX_check_private_key error!\n");        return NULL;    }    // 将连接付给SSL      ssl = SSL_new (ctx);    if(!ssl)    {        printf("SSL_new error!\n");        return NULL;    }    SSL_set_fd (ssl, fd);      if(SSL_accept (ssl) != 1)    {        int icode = -1;        int iret = SSL_get_error(ssl, icode);        printf("SSL_accept error! code = %d, iret = %d\n", icode, iret);        return NULL;    }    return ssl;}void socket_read_cb(evutil_socket_t fd, short events, void *arg){    SSL* ssl = (SSL*)arg;    char msg[4096];    memset(msg, 0, sizeof(msg));      int nLen = SSL_read(ssl,msg, sizeof(msg));      fprintf(stderr, "Get Len %d %s ok\n", nLen, msg);      strcat(msg, "\n this is from server========server resend to client");      SSL_write(ssl, msg, strlen(msg));}void do_accept(evutil_socket_t listener, short event, void *arg){    printf("do_accept\n");    struct event_base *base = (struct event_base*)arg;    struct sockaddr_storage ss;    socklen_t slen = sizeof(ss);    int fd = accept(listener, (struct sockaddr*)&ss, &slen);    if (fd < 0)    {        perror("accept");    }    else if (fd > FD_SETSIZE)    {        close(fd);    }    else    {        SSL* ssl = CreateSSL(fd);        struct event *ev = event_new(NULL, -1, 0, NULL, NULL);        //将动态创建的结构体作为event的回调参数        event_assign(ev, base, fd, EV_READ | EV_PERSIST,                 socket_read_cb, (void*)ssl);    event_add(ev, NULL);    }}void run(void){    evutil_socket_t listener;    struct sockaddr_in sin;    struct event_base *base;    struct event *listener_event;    base = event_base_new();    if (!base)        return; /*XXXerr*/    sin.sin_family = AF_INET;    sin.sin_addr.s_addr = 0;    sin.sin_port = htons(8080);    listener = socket(AF_INET, SOCK_STREAM, 0);    evutil_make_socket_nonblocking(listener);#ifndef WIN32    {        int one = 1;        setsockopt(listener, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));    }#endif    if (bind(listener, (struct sockaddr*)&sin, sizeof(sin)) < 0)    {        perror("bind");        return;    }    if (listen(listener, 16)<0)    {        perror("listen");        return;    }    listener_event = event_new(base, listener, EV_READ|EV_PERSIST, do_accept, (void*)base);    event_add(listener_event, NULL);    event_base_dispatch(base);}int main(int argc, char **argv){    setvbuf(stdout, NULL, _IONBF, 0);    SSL_library_init();    SSL_load_error_strings();    OpenSSL_add_all_algorithms();    run();    return 0;}

编写makefile或者直接使用命令进行编译，得到可执行文件test
libevent服务端：

[root@localhost LibeventSSL]# ./test do_acceptGet Len 56 this is from client+++++++++++++++client send to server okGet Len 0  okGet Len 0  ok[root@localhost LibeventSSL]#

客户端：

[root@localhost SSLTestC]# ./test Server Running in LINUXSSL_CTX_load_verify_locations start!Get Len 108 this is from client+++++++++++++++client send to server this is from server========server resend to client ok[root@localhost SSLTestC]# 

表明客户端跟服务器已经正常通信，同样的，进行抓包分析的话，得到只能是
不可识别的乱码，表明通信会话已经加密，ssl功能已经生效

此篇博文跟前面的 openssl编程之服务端有一个需要注意的地方，若socket为
非阻塞，在进行SSL_accept和SSL_read SSL_wirte时需要注意，此程序只是实现了加密和通信，并未处理服务器连接的问题，比如客户端关闭连接等，表现形式如：服务器端打印了两次的：

Get Len 0  okGet Len 0  ok

后面面将专门
写一篇博文进行讲解