转SSL连接建立过程分析

1、.转 SSL连接建立过程分析 42.13 SSL_connect  SSL_connect这个函数完成SSL协商的客户端操作:/* ssl/ssl_lib.c */int SSL_connectSSL *s  if s->handshake_func = 0  /* Not properly initialized yet */  SSL_set_connect_states; returns->method->ssl_connects; 其中SSL_set_connect_states

2、函数初始化SSL协商处理:void SSL_set_connect_stateSSL *s / 客户端 s->server=0; s->shutdown=0;/ 初始化客户端状态值 s->state=SSL_ST_CONNECT|SSL_ST_BEFORE;/ 握手函数即是ssl_connect函数 s->handshake_func=s->method->ssl_connect; /* clear the current cipher */ 去除SSL读写加密算法上下文 ssl_clea

3、r_cipher_ctxs; 因此最重要的就是ssl_connect这两个成员函数，是前面SSLv23_client_method函数中定义的，如对于SSLv23方法，处理函数分别为ssl23_connect函数，其它SSLv2和SSLv3方法分别对应ssl2_connect和ssl3_connect，后两者就没有协商过程了，ssl23_connect实际在协商确定协议版本后也是调用ssl23_connect。掌握了服务器端的accept过程，理解客户端的connect过程就简单了。/* ssl/s23_clnt.c */int ssl23_connectSSL *s &#

4、160;BUF_MEM *buf=NULL; unsigned long Time=timeNULL; void *cbconst SSL *ssl,int type,int val=NULL; int ret= -1; int new_state,state;/ 和服务器端一样进行根本的初始化 RAND_add&Time,sizeofTime,0; ERR_clear_error; clear_sys_error; if s->info_callback != NULL  cb=

5、s->info_callback; else if s->ctx->info_callback != NULL  cb=s->ctx->info_callback; s->in_handshake+; if !SSL_in_inits | SSL_in_befores SSL_clears;  for ;    state=s->state;/ 在SSL_set_connect_state中s->state被初始化为SSL_ST_CONNECT|S

6、SL_ST_BEFORE  switchs->state     case SSL_ST_BEFORE:  case SSL_ST_CONNECT:  case SSL_ST_BEFORE|SSL_ST_CONNECT:  case SSL_ST_OK|SSL_ST_CONNECT:/ 进行根本初始化,分配缓冲区   if s->session != NULL     

7、60;  SSLerrSSL_F_SSL23_CONNECT,SSL_R_SSL23_DOING_SESSION_ID_REUSE;    ret= -1;    goto end;       s->server=0;   if cb != NULL cbs,SSL_CB_HANDSHAKE_START,1;   /* s->version=TLS1_V

8、ERSION; */   s->type=SSL_ST_CONNECT;   if s->init_buf = NULL        if buf=BUF_MEM_new = NULL          ret= -1;     goto end;    

9、     if !BUF_MEM_growbuf,SSL3_RT_MAX_PLAIN_LENGTH          ret= -1;     goto end;         s->init_buf=buf;    buf=NULL;  &

10、#160;    if !ssl3_setup_bufferss ret= -1; goto end;    ssl3_init_finished_macs;/ SSL客户端状态转为准备发送HELLO信息   s->state=SSL23_ST_CW_CLNT_HELLO_A;   s->ctx->stats.sess_connect+;   s->init_num=0;   bre

11、ak;  case SSL23_ST_CW_CLNT_HELLO_A:  case SSL23_ST_CW_CLNT_HELLO_B:/ 发送客户端的HELLO信息   s->shutdown=0;   ret=ssl23_client_hellos;   if ret <= 0 goto end;/ 转为准备接收服务器端的HELLO状态   s->state=SSL23_ST_CR_SRVR_HELLO_A;

12、0;  s->init_num=0;   break;  case SSL23_ST_CR_SRVR_HELLO_A:  case SSL23_ST_CR_SRVR_HELLO_B:/ 读取服务器端的HELLO信息,完成SSL握手协商   ret=ssl23_get_server_hellos;   if ret >= 0 cb=NULL;   goto end;   /*

13、break; */  default:   SSLerrSSL_F_SSL23_CONNECT,SSL_R_UNKNOWN_STATE;   ret= -1;   goto end;   /* break; */     if s->debug voidBIO_flushs->wbio;   if cb != NULL && s->state != st

14、ate      new_state=s->state;   s->state=state;   cbs,SSL_CB_CONNECT_LOOP,1;   s->state=new_state;     end: s->in_handshake-; if buf != NULL  BUF_MEM_freebuf; if cb

15、 != NULL  cbs,SSL_CB_CONNECT_EXIT,ret; returnret;  ssl23_client_hello函数发送客户端的HELLO信息:/* ssl/s23_clnt.c */static int ssl23_client_helloSSL *s  unsigned char *buf; unsigned char *p,*d; int i,ch_len; int ret; buf=unsigned char *s->init_buf->d

16、ata; if s->state = SSL23_ST_CW_CLNT_HELLO_A  / 准备发送HELLO, 构造发送缓冲区的数据,数据格式见SSL_accept一节中的说明  p=s->s3->client_random;  RAND_pseudo_bytesp,SSL3_RANDOM_SIZE;  /* Do the message type and length last */  d= &buf2;/ p指向SSL握手记录头11字节长后的第一字节处

17、  p=d+9;/ 消息类型  *d+=SSL2_MT_CLIENT_HELLO;/ 填写客户端版本号  if !s->options & SSL_OP_NO_TLSv1      *d+=TLS1_VERSION_MAJOR;   *d+=TLS1_VERSION_MINOR;   s->client_version=TLS1_VERSION;    &#

18、160;else if !s->options & SSL_OP_NO_SSLv3      *d+=SSL3_VERSION_MAJOR;   *d+=SSL3_VERSION_MINOR;   s->client_version=SSL3_VERSION;     else if !s->options & SSL_OP_NO_SSLv2    &#

19、160; *d+=SSL2_VERSION_MAJOR;   *d+=SSL2_VERSION_MINOR;   s->client_version=SSL2_VERSION;     else      SSLerrSSL_F_SSL23_CLIENT_HELLO,SSL_R_NO_PROTOCOLS_AVAILABLE;   return-1;   

20、;/ 填写cipher_specs信息  /* Ciphers supported */  i=ssl_cipher_list_to_bytess,SSL_get_cipherss,p;  if i = 0      /* no ciphers */   SSLerrSSL_F_SSL23_CLIENT_HELLO,SSL_R_NO_CIPHERS_AVAILABLE;   return-1;  

21、   s2ni,d;  p+=i;/ 填写会话ID  /* put in the session-id, zero since there is no   * reuse. */  s2n0,d;  if s->options & SSL_OP_NETSCAPE_CHALLENGE_BUG   ch_len=SSL2_CHALLENGE_LENGTH;  else   ch

22、_len=SSL2_MAX_CHALLENGE_LENGTH;/ 填写挑战信息  /* write out sslv2 challenge */  if SSL3_RANDOM_SIZE < ch_len   i=SSL3_RANDOM_SIZE;  else   i=ch_len;  s2ni,d;  memset&s->s3->client_random0,0,SSL3_RANDOM_SIZE; 

23、 RAND_pseudo_bytes&s->s3->client_randomSSL3_RANDOM_SIZE-i,i;  memcpyp,&s->s3->client_randomSSL3_RANDOM_SIZE-i,i;  p+=i;/ 数据长度  i= p- &buf2;  buf0=i>>8&0xff|0x80;  buf1=i&0xff;/ 数据完成,状态转为HELLO B准备发送 

24、0;s->state=SSL23_ST_CW_CLNT_HELLO_B;  /* number of bytes to write */  s->init_num=i+2;  s->init_off=0;  ssl3_finish_macs,&buf2,i;   /* SSL3_ST_CW_CLNT_HELLO_B */ 发送HELLO数据 ret = ssl23_write_bytess; if ret >= 2 

25、0;if s->msg_callback   s->msg_callback1, SSL2_VERSION, 0, s->init_buf->data+2, ret-2, s, s->msg_callback_arg; /* CLIENT-HELLO */ return ret; ssl23_get_server_hello接收服务器端的回应，识别服务器的SSL版本，最后再相应调用ssl2_connect或ssl3_connect函数。/* ssl/s23_clnt.c */static int ssl23_get

26、_server_helloSSL *s  char buf8; unsigned char *p; int i; int n;/ 读7字节的服务器端数据 n=ssl23_read_bytess,7; if n != 7 returnn; p=s->packet; memcpybuf,p,n; if p0 & 0x80 && p2 = SSL2_MT_SERVER_HELLO &&  p5 = 0x00 && p6

27、= 0x02  / 服务器是SSL2版本#ifdef OPENSSL_NO_SSL2  SSLerrSSL_F_SSL23_GET_SERVER_HELLO,SSL_R_UNSUPPORTED_PROTOCOL;  goto err;#else  /* we are talking sslv2 */  /* we need to clean up the SSLv3 setup and put in the   * sslv2 stuff. */  int

28、 ch_len;  if s->options & SSL_OP_NO_SSLv2      SSLerrSSL_F_SSL23_GET_SERVER_HELLO,SSL_R_UNSUPPORTED_PROTOCOL;   goto err;   / 初始化SSL结构中的SSL2支持，ssl_connect将为ssl2_connect  if s->s2 = NULL    &

29、#160; if !ssl2_news    goto err;     else   ssl2_clears;  if s->options & SSL_OP_NETSCAPE_CHALLENGE_BUG   ch_len=SSL2_CHALLENGE_LENGTH;  else   ch_len=SSL2_MAX_CHALLENGE_LENGTH;&

30、#160; /* write out sslv2 challenge */  i=SSL3_RANDOM_SIZE < ch_len   ?SSL3_RANDOM_SIZE:ch_len;  s->s2->challenge_length=i;  memcpys->s2->challenge,   &s->s3->client_randomSSL3_RANDOM_SIZE-i,i;  if s-&

31、gt;s3 != NULL ssl3_frees;  if !BUF_MEM_grow_cleans->init_buf,   SSL2_MAX_RECORD_LENGTH_3_BYTE_HEADER      SSLerrSSL_F_SSL23_GET_SERVER_HELLO,ERR_R_BUF_LIB;   goto err;     s->state=SSL2_ST_GET_SERVER

32、_HELLO_A;  if !s->client_version = SSL2_VERSION   /* use special padding SSL 3.0 draft/RFC 2246, App. E.2 */   s->s2->ssl2_rollback=1;  /* setup the 5 bytes we have read so we get them from   * the sslv2 buffer */  s->

33、rstate=SSL_ST_READ_HEADER;  s->packet_length=n;  s->packet= &s->s2->rbuf0;  memcpys->packet,buf,n;  s->s2->rbuf_left=n;  s->s2->rbuf_offs=0;  /* we have already written one */  s->s2->write_seq

34、uence=1;  s->method=SSLv2_client_method;  s->handshake_func=s->method->ssl_connect;#endif   else if p0 = SSL3_RT_HANDSHAKE &&   p1 = SSL3_VERSION_MAJOR &&   p2 = SSL3_VERSION_MINOR |    p2 = TLS1_VERSIO

35、N_MINOR &&   p5 = SSL3_MT_SERVER_HELLO  / 服务器版本为SSL3或TLS1，ssl_connect将为ssl3_connect  /* we have sslv3 or tls1 */  if !ssl_init_wbio_buffers,1 goto err;  /* we are in this state */  s->state=SSL3_ST_CR_SRVR_HELLO_A;  /*

36、put the 5 bytes we have read into the input buffer   * for SSLv3 */  s->rstate=SSL_ST_READ_HEADER;  s->packet_length=n;  s->packet= &s->s3->rbuf.buf0;  memcpys->packet,buf,n;  s->s3->rbuf.left=n;  s->

37、;s3->rbuf.offset=0;  if p2 = SSL3_VERSION_MINOR &&   !s->options & SSL_OP_NO_SSLv3      s->version=SSL3_VERSION;   s->method=SSLv3_client_method;     else if p2 = TLS1_VERSION_MINOR

38、 &&   !s->options & SSL_OP_NO_TLSv1      s->version=TLS1_VERSION;   s->method=TLSv1_client_method;     else      SSLerrSSL_F_SSL23_GET_SERVER_HELLO,SSL_R_UNSUPPORTE

39、D_PROTOCOL;   goto err;        s->handshake_func=s->method->ssl_connect;   else if p0 = SSL3_RT_ALERT &&   p1 = SSL3_VERSION_MAJOR &&   p2 = SSL3_VERSION_MINOR |    p2 =

40、TLS1_VERSION_MINOR &&   p3 = 0 &&   p4 = 2  / SSL告警信息  void *cbconst SSL *ssl,int type,int val=NULL;  int j;  /* An alert */  if s->info_callback != NULL   cb=s->info_callback;  else

41、if s->ctx->info_callback != NULL   cb=s->ctx->info_callback;   i=p5;  if cb != NULL      j=i<<8|p6;   cbs,SSL_CB_READ_ALERT,j;     s->rwstate=SSL_NOTHING;  SSL

42、errSSL_F_SSL23_GET_SERVER_HELLO,SSL_AD_REASON_OFFSET+p6;  goto err;   else    SSLerrSSL_F_SSL23_GET_SERVER_HELLO,SSL_R_UNKNOWN_PROTOCOL;  goto err;   s->init_num=0; /* Since, if we are sending a ssl23 client hello, we are

43、not  * reusing a session-id */ if !ssl_get_new_sessions,0  goto err; s->first_packet=1;/ 递归调用SSL_connect，实际将执行ssl2_connect或ssl3_connect returnSSL_connects;err: return-1;  举例ssl3_conect函数定义如下，ssl2_connect就不分析了:/* ssl/s3_clnt.c */int ssl3_connectSSL *s&#

44、160; BUF_MEM *buf=NULL; unsigned long Time=timeNULL,l; long num1; void *cbconst SSL *ssl,int type,int val=NULL; int ret= -1; int new_state,state,skip=0;/ 对SSL3连接的初始化 RAND_add&Time,sizeofTime,0; ERR_clear_error; clear_sys_error; if s->info_call

45、back != NULL  cb=s->info_callback; else if s->ctx->info_callback != NULL  cb=s->ctx->info_callback;  s->in_handshake+; if !SSL_in_inits | SSL_in_befores SSL_clears;  for ;    state=s->state;  switchs->

46、state     case SSL_ST_RENEGOTIATE:/ 重协商的话从头开场, 注意break是注释掉的   s->new_session=1;   s->state=SSL_ST_CONNECT;   s->ctx->stats.sess_connect_renegotiate+;   /* break */ 初始状态应该是SSL_ST_BEFORE|SSL_ST_CONNECT

47、0; case SSL_ST_BEFORE:  case SSL_ST_CONNECT:  case SSL_ST_BEFORE|SSL_ST_CONNECT:  case SSL_ST_OK|SSL_ST_CONNECT:/ server=0表示是客户端   s->server=0;   if cb != NULL cbs,SSL_CB_HANDSHAKE_START,1;/ 假设本地版本不是SSL3那么出错   if s-&g

48、t;version & 0xff00 != 0x0300        SSLerrSSL_F_SSL3_CONNECT, ERR_R_INTERNAL_ERROR;    ret = -1;    goto end;       /* s->version=SSL3_VERSION; */   s->type=SSL

49、_ST_CONNECT;/ 初始化连接缓冲区   if s->init_buf = NULL        if buf=BUF_MEM_new = NULL          ret= -1;     goto end;         if

50、 !BUF_MEM_growbuf,SSL3_RT_MAX_PLAIN_LENGTH          ret= -1;     goto end;         s->init_buf=buf;    buf=NULL;       if

51、!ssl3_setup_bufferss ret= -1; goto end;    /* setup buffing BIO */   if !ssl_init_wbio_buffers,0 ret= -1; goto end;    /* don't push the buffering BIO quite yet */   ssl3_init_finished_macs;/ 准备发送HELLO信息   s->state=SSL

52、3_ST_CW_CLNT_HELLO_A;   s->ctx->stats.sess_connect+;   s->init_num=0;   break;  case SSL3_ST_CW_CLNT_HELLO_A:  case SSL3_ST_CW_CLNT_HELLO_B:/ 该状态发送客户端SSL3信息   s->shutdown=0;   ret=ssl3_client_h

53、ellos;   if ret <= 0 goto end;/ 发送成功,状态转为准备接收服务器的HELLO回应   s->state=SSL3_ST_CR_SRVR_HELLO_A;   s->init_num=0;   /* turn on buffering for the next lot of output */   if s->bbio != s->wbio    

54、s->wbio=BIO_pushs->bbio,s->wbio;   break;  case SSL3_ST_CR_SRVR_HELLO_A:  case SSL3_ST_CR_SRVR_HELLO_B:/ 该状态下接收服务器发送的HELLO信息   ret=ssl3_get_server_hellos;   if ret <= 0 goto end;   if s->hit/ 假设是reuse的连接,状

55、态转为接收结束    s->state=SSL3_ST_CR_FINISHED_A;   else/ 否那么状态转为准备接收服务器的证书    s->state=SSL3_ST_CR_CERT_A;   s->init_num=0;   break;  case SSL3_ST_CR_CERT_A:  case SSL3_ST_CR_CERT_B:/ 该状态下接收服务器

56、发送的证书   /* Check if it is anon DH */   if !s->s3->tmp.new_cipher->algorithms & SSL_aNULL        ret=ssl3_get_server_certificates;    if ret <= 0 goto end;      

57、0;else    skip=1;/ 状态转为接收密钥交换信息   s->state=SSL3_ST_CR_KEY_EXCH_A;   s->init_num=0;   break;  case SSL3_ST_CR_KEY_EXCH_A:  case SSL3_ST_CR_KEY_EXCH_B:/ 该状态下接收密钥交换信息   ret=ssl3_get_key_exchanges;&

58、#160;  if ret <= 0 goto end;/ 状态转为接收证书请求   s->state=SSL3_ST_CR_CERT_REQ_A;   s->init_num=0;   /* at this point we check that we have the    * required stuff from the server */   if !ssl3_check_cert_and_algo

59、rithms        ret= -1;    goto end;       break;  case SSL3_ST_CR_CERT_REQ_A:  case SSL3_ST_CR_CERT_REQ_B:/ 该状态下接收服务器的证书请求   ret=ssl3_get_certificate_requests;  

60、; if ret <= 0 goto end;   s->state=SSL3_ST_CR_SRVR_DONE_A;   s->init_num=0;   break;  case SSL3_ST_CR_SRVR_DONE_A:  case SSL3_ST_CR_SRVR_DONE_B:/ 该状态下接收服务器信息结束   ret=ssl3_get_server_dones;   

61、if ret <= 0 goto end;   if s->s3->tmp.cert_req/ 发送客户端证书    s->state=SSL3_ST_CW_CERT_A;   else/ 发送密钥交换信息    s->state=SSL3_ST_CW_KEY_EXCH_A;   s->init_num=0;   break;  case S

62、SL3_ST_CW_CERT_A:  case SSL3_ST_CW_CERT_B:  case SSL3_ST_CW_CERT_C:  case SSL3_ST_CW_CERT_D:/ 该状态下发送客户端证书   ret=ssl3_send_client_certificates;   if ret <= 0 goto end;/ 状态转为发送密钥交换信息   s->state=SSL3_ST_CW_KEY_EXCH_A; 

63、;  s->init_num=0;   break;  case SSL3_ST_CW_KEY_EXCH_A:  case SSL3_ST_CW_KEY_EXCH_B:/ 该状态下发送密钥交换信息   ret=ssl3_send_client_key_exchanges;   if ret <= 0 goto end;/ 加密算法   l=s->s3->tmp.new_cipher->a

64、lgorithms;   /* EAY EAY EAY need to check for DH fix cert    * sent back */   /* For TLS, cert_req is set to 2, so a cert chain    * of nothing is sent, but no verify packet is sent */   if s->s3->tmp.cert_req = 1 

65、   / 发送证书验证    s->state=SSL3_ST_CW_CERT_VRFY_A;       else    / TLS, 不用发送证书认证信息,直接转为修改算法状态    s->state=SSL3_ST_CW_CHANGE_A;    s->s3->change_cipher_spec=0;

66、60;      s->init_num=0;   break;  case SSL3_ST_CW_CERT_VRFY_A:  case SSL3_ST_CW_CERT_VRFY_B:/ 该状态发送证书验证信息   ret=ssl3_send_client_verifys;   if ret <= 0 goto end;/ 状态转为发送修改算法信息   s->

67、state=SSL3_ST_CW_CHANGE_A;   s->init_num=0;   s->s3->change_cipher_spec=0;   break;  case SSL3_ST_CW_CHANGE_A:  case SSL3_ST_CW_CHANGE_B:/ 该状态下发送修改算法信息   ret=ssl3_send_change_cipher_specs,    

68、;SSL3_ST_CW_CHANGE_A,SSL3_ST_CW_CHANGE_B;   if ret <= 0 goto end;/ 状态转为发送结束   s->state=SSL3_ST_CW_FINISHED_A;   s->init_num=0;/ 设置会话加密算法   s->session->cipher=s->s3->tmp.new_cipher;   if s->s3->tmp.n

69、ew_compression = NULL    s->session->compress_meth=0;   else    s->session->compress_meth=     s->s3->tmp.new_compression->id;   if !s->method->ssl3_enc->setup_key_blocks 

70、;       ret= -1;    goto end;       if !s->method->ssl3_enc->change_cipher_states,    SSL3_CHANGE_CIPHER_CLIENT_WRITE        ret= -1; &#

71、160;  goto end;       break;  case SSL3_ST_CW_FINISHED_A:  case SSL3_ST_CW_FINISHED_B:/ 该状态下发送协商结束信息   ret=ssl3_send_finisheds,    SSL3_ST_CW_FINISHED_A,SSL3_ST_CW_FINISHED_B,    s

72、->method->ssl3_enc->client_finished_label,    s->method->ssl3_enc->client_finished_label_len;   if ret <= 0 goto end;/ 转为刷新写缓冲状态   s->state=SSL3_ST_CW_FLUSH;   /* clear flags */   s->s3->fla

73、gs&= SSL3_FLAGS_POP_BUFFER;   if s->hit    / 假设是reuse的会话, FLUSH后的下一个状态转为协商成功    s->s3->tmp.next_state=SSL_ST_OK;    if s->s3->flags & SSL3_FLAGS_DELAY_CLIENT_FINISHED      

74、    s->state=SSL_ST_OK;     s->s3->flags|=SSL3_FLAGS_POP_BUFFER;     s->s3->delay_buf_pop_ret=0;            else    / 否那么状态转为准备接收服务器的协商

75、结束信息    s->s3->tmp.next_state=SSL3_ST_CR_FINISHED_A;       s->init_num=0;   break;  case SSL3_ST_CR_FINISHED_A:  case SSL3_ST_CR_FINISHED_B:/ 该状态接收服务器发送的协商结束信息   ret=ssl3_get_finisheds,S

76、SL3_ST_CR_FINISHED_A,    SSL3_ST_CR_FINISHED_B;   if ret <= 0 goto end;   if s->hit/ 假设会话是reuse的,状态转为发送算法    s->state=SSL3_ST_CW_CHANGE_A;   else/ 否那么协商成功    s->state=SSL_ST_OK;   s->init_num=0;   break;  case SSL3_ST_CW_FLUSH:/ 该状态下刷新写缓冲区   /* number of bytes to be flushed */   num1=BIO_ctrls->wbi