Hi,
The client and server that I have in my project runs in a simple 1 socket,
blocking mode environment. The model
is that of a typical producer-consumer one. The client produces data, sends
it to the server. The server
consumes it. Once in a while, the server sends a control message to the
client that the client periodically
receives. Below is a simplified version of the client and server after
enabling them for SSL/TLS communication.
1 Client:
2 -------
3 while (true)
4 {
5 if (poll(pollin, timeout=0) || 0 < SSL_pending(ssl))
6 {
7 SSL_read();
8 // Handle WANT_READ or WANT_WRITE appropriately.
9 // If no error, handle the received control message.
10 }
11 // produce data.
12 while (!poll(pollout))
13 ; // Wait until the TCP/IP pipe is ready for
a send().
14 SSL_write();
15 // Handle WANT_READ or WANT_WRITE appropriately.
16 if (time to renegotiate)
17 SSL_renegotiate(ssl);
18 }
19
20 Server:
21 -------
22 while (true)
23 {
24 if (poll(pollin, timeout=1s) || 0 < SSL_pending(ssl))
25 {
26 SSL_read();
27 // Handle WANT_READ or WANT_WRITE appropriately.
28 // If no error, consume data.
29 }
30 if (control message needs to be sent)
31 {
32 while (!poll(pollout))
33 ; // Wait until the TCP/IP pipe is
ready for a send().
34 SSL_write();
35 // Handle WANT_READ or WANT_WRITE appropriately.
36 }
37 }
The trouble happens when I force, for testing purposes, SSL/TLS
renegotiation by calling SSL_renegoitate()
once in a while on the client (lines 16-17). I don't do any follow up
SSL_do_handshake as I assume the
subsequent SSL_write/SSL_read will take care of it automatically.
The session starts of nice and easy. A few messages are transmitted and in
fact, a few forced SSL/TLS
renegotiations happen successfully as well. But, sometime later, I get an
SSL_ERROR_SSL from SSL_write on the
client and SSL_ERROR_SSL from SSL_read on the server. Below are the error
details:
Client:
-------
error:140940F5:SSL routines:SSL3_READ_BYTES:unexpected record
Server:
-------
error:140943F2:SSL routines:SSL3_READ_BYTES:sslv3 alert unexpected message
What am I doing wrong? Is there anything that needs to be taken care of
when handling SSL/TLS renegotiations in
cases where bidirectional socket communications is used?
Any help is appreciated.
Thanks,
Karthik.
