这篇文章探索TLS -ticket 的重用机制.
完整的SSL握手过程为:
Client Server
ClientHello
(empty SessionTicket extension)-------->
ServerHello
(empty SessionTicket extension)
Certificate*
ServerKeyExchange*
CertificateRequest*
<-------- ServerHelloDone
Certificate*
ClientKeyExchange
CertificateVerify*
[ChangeCipherSpec]
Finished -------->
NewSessionTicket
[ChangeCipherSpec]
<-------- Finished
Application Data <-------> Application Data
使用TLS-ticket 的session复用机制时
Client Server
ClientHello
(SessionTicket extension) -------->
ServerHello
(empty SessionTicket extension)
NewSessionTicket
[ChangeCipherSpec]
<-------- Finished
[ChangeCipherSpec]
Finished -------->
Application Data <-------> Application Data
可见复用session可以缩短建立连接的时间.
复用session的流程:
在一次完整的SSL握手过程中,服务端会将ticket返回给客户端,客户端将此ticket保存,下次再进行连接时携带此ticket便可以回复session.
需要注意的是,ticket是ssl_st中的一个字段不能够单独保存,需要将整个session进行保存.
流程:
a. client1.cpp中建立SSL连接后,通过SSL_SESSION *session0 = SSL_get_session(ssl);得到session,然后通过PEM_write_SSL_SESSION(fp, session0);将session保存至文件中
b. client2.cpp若想重用上面的session,需要通过PEM_read_SSL_SESSION(fp, NULL, NULL, NULL);从文件中读取session.
c. 然后通过SSL_set_session(ssl, session_new);将其设置,这样便实现了连接复用.
注意:必须调用SSL_set_session(ssl, session_new);将其设置,否则仍是完整的连接.
示例代码如下:
client1.cpp(将session保存)
int main(int argc, char * *argv) {
int sockfd, len;
struct sockaddr_in dest;
char buffer[MAXBUF + 1];
SSL_CTX * ctx;
SSL * ssl;
/* SSL 库初始化*/
SSL_library_init();
/* 载入所有SSL 算法*/OpenSSL_add_all_algorithms();
/* 载入所有SSL 错误消息*/
SSL_load_error_strings();
/* 以SSL V2 和V3 标准兼容方式产生一个SSL_CTX ，即SSL Content Text */
ctx = SSL_CTX_new(SSLv23_client_method());
if (ctx == NULL) {
ERR_print_errors_fp(stdout);
exit(1);
}
/* 创建一个socket 用于tcp 通信*/
if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
perror("Socket");
exit(errno);
}
printf("socket created\n");
/* 初始化服务器端（对方）的地址和端口信息*/
bzero(&dest, sizeof(dest));
dest.sin_family = AF_INET;
//设置连接的端口
dest.sin_port = htons(443);
//设置连接的IP地址
char *addr3 = "115.239.210.27";
if (inet_aton(addr3, (struct in_addr *) &dest.sin_addr.s_addr) == 0) {
perror(argv[0]);
exit(errno);
}
printf("address created\n");
/* 连接服务器*/
if (connect(sockfd, (struct sockaddr *) &dest, sizeof(dest)) != 0) {
perror("Connect ");
exit(errno);
}
printf("server connected\n");
/* 基于ctx 产生一个新的SSL */
ssl = SSL_new(ctx);
/* 将新连接的socket 加入到SSL */
SSL_set_fd(ssl, sockfd);
/* 建立SSL 连接*/
if (SSL_connect(ssl) == -1) {
ERR_print_errors_fp(stderr);
} else {
printf("Connected with %s encryption\n", SSL_get_cipher(ssl));
ShowCerts(ssl);
}
SSL_SESSION *session0 = SSL_get_session(ssl);
FILE * fp;
int leng = 20;
int numwritten = 0;
char data[leng];
fp = fopen("/home/shuyan/file1.txt", "w+");
if (fp == NULL) {
printf("can't open file \n");
} else {
printf("open sucess\n");
//将session 保存至文件中
<span style="color:#ff0000;">PEM_write_SSL_SESSION(fp, session0);</span>
fclose(fp);
}
unsigned char * session_id1 = session0->session_id;
//cout << "sessionid : " << session_id << endl;
int len3 = session0->session_id_length;
cout << "session length:" << len3 << endl;
unsigned char * ticket1 = session0->tlsext_tick;
cout << "ticket:" << ticket1 << endl;
size_t ticklen1 = session0->tlsext_ticklen;
cout << "ticklen:" << ticklen1 << endl;
long tick_lifetime_hint1 = session0->tlsext_tick_lifetime_hint;
cout << "tick_lifetime_hint:" << tick_lifetime_hint1 << endl;
/* 关闭连接*/
SSL_shutdown(ssl);
SSL_free(ssl);
close(sockfd);
SSL_CTX_free(ctx);
return 0;
}int main(int argc, char * *argv) {
int sockfd;
struct sockaddr_in dest;
char buffer[MAXBUF + 1];
SSL_CTX * ctx;
SSL * ssl;
FILE *fp;
/* SSL 库初始化*/
SSL_library_init();
/* 载入所有SSL 算法*/OpenSSL_add_all_algorithms();
/* 载入所有SSL 错误消息*/
SSL_load_error_strings();
//---------------------------再次连接--------------------------------------
//这里从文件中恢复session
fp = fopen("/home/shuyan/file1.txt", "r");
<span style="color:#ff0000;">SSL_SESSION * session_new = PEM_read_SSL_SESSION(fp, NULL, NULL, NULL);</span>
if (session_new != NULL) {
unsigned char * ticket2 = session_new->tlsext_tick;
cout << "new ticket :" << ticket2 << endl;
} else {
cout << "=======NULL========" << endl;
}
ctx = SSL_CTX_new(SSLv23_client_method());
/* 基于ctx 产生一个新的SSL */
ssl = SSL_new(ctx);
//必须有这一步骤,否则不会进行复用.
SSL_set_session(ssl, session_new);
/* 创建一个socket 用于tcp 通信*/
if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
perror("Socket");
exit(errno);
}
printf("socket created\n");
/* 初始化服务器端（对方）的地址和端口信息*/
bzero(&dest, sizeof(dest));
dest.sin_family = AF_INET;
//设置连接的端口
dest.sin_port = htons(443);
//设置连接的IP地址
char *addr2 = "115.239.210.27";
if (inet_aton(addr2, (struct in_addr *) &dest.sin_addr.s_addr) == 0) {
perror(argv[0]);
exit(errno);
}
printf("address created\n");
/* 连接服务器*/
if (connect(sockfd, (struct sockaddr *) &dest, sizeof(dest)) != 0) {
perror("Connect ");
exit(errno);
}
printf("server connected\n");
/* 将新连接的socket 加入到SSL */
SSL_set_fd(ssl, sockfd);
/* 建立SSL 连接*/
if (SSL_connect(ssl) == -1) {
ERR_print_errors_fp(stderr);
} else {
printf("Connected with %s encryption\n", SSL_get_cipher(ssl));
ShowCerts(ssl);
}
SSL_SESSION *session2 = SSL_get_session(ssl);
int len2 = session2->session_id_length;
cout << "session length:" << len2 << endl;
unsigned char * ticket2 = session2->tlsext_tick;
cout << "ticket:" << ticket2 << endl;
size_t ticklen2 = session2->tlsext_ticklen;
cout << "ticklen:" << ticklen2 << endl;
long tick_lifetime_hint2 = session2->tlsext_tick_lifetime_hint;
cout << "tick_lifetime_hint:" << tick_lifetime_hint2 << endl;
/* 关闭连接*/
SSL_shutdown(ssl);
SSL_free(ssl);
close(sockfd);
SSL_CTX_free(ctx);
return 0;
}
原文地址：http://blog.csdn.net/leokelly001/article/details/44307171
