On Mar 28, 2013, at 12:22 AM, Daniel Caiafa wrote: > tl;dr: I've been looking into an issue in my product (uses DTLS) for the last > couple of days. Tracked it down to a CHANGE_CIPHER_SPEC being processed too > early causing the handshake to never complete. > > Details: > > - OpenSSL version 1.0.1c > - Brackets indicate a single datagram packet. > > (1) Client: send [SSL3_MT_CLIENT_HELLO] > (2) Server: send [SSL3_MT_SERVER_HELLO, SSL3_MT_CERTIFICATE, > SSL3_MT_CERTIFICATE_REQUEST, SSL3_MT_SERVER_DONE] > (3) Client: send [SSL3_MT_CERTIFICATE, SSL3_MT_CLIENT_KEY_EXCHANGE, > SSL3_MT_CERTIFICATE_VERIFY, *CHANGE_CIPHER*, SSL3_MT_FINISHED] > > Client packet (3) is lost. Oh noes! Other stuff happens, but Client > eventually resends each message in its own datagram this time: > > (4) Client: send [SSL3_MT_CERTIFICATE] > (5) Client: send [SSL3_MT_CLIENT_KEY_EXCHANGE] > (6) Client: send [SSL3_MT_CERTIFICATE_VERIFY] > (7) Client: send [*CHANGE_CIPHER*] > (8) Client: send [SSL3_MT_FINISHED] > > Now, one of the following thing happens: a) packet (6) is lost or, in my > case, packet (7) arrives before (6). > > Unfortunately, when Server processes packet (7) it changes the cypher spec > before the handshake is over. When (6) finally arrives, it's dropped by > dtls1_read_bytes. Subsequent re-sends from Client are also ignored. > > Without having read any spec, and with my limited knowledge of the OpenSSL > codebase, my naive interpretation is that the problem is caused by > dtls1_accept setting change_cipher_spec_ok on SSL3_ST_SR_CERT_VRFY_* states. > > Commenting out that line definitely seems to fix the problem for me. Is this > really the bug, or does that line plays a role in a different scenario? Hi Daniel,
this really sounds like a bug. Can you file one using the request tracker at http://www.openssl.org/support/rt.html This way it doesn't get lost and a fix can be tied to it. Thanks a lot. Best regards Michael > > Cheers, > -dan > > > > > > > ______________________________________________________________________ OpenSSL Project http://www.openssl.org Development Mailing List openssl-dev@openssl.org Automated List Manager majord...@openssl.org
