mirror/openssl
2
0
Fork 0
mirror of https://github.com/openssl/openssl.git synced 2025-02-23 14:42:15 +08:00
Code Issues Packages Projects Releases Wiki Activity
af33b200da
openssl/ssl/statem
History
Matt Caswell 16f0e91cf8 Partial revert and reimplement "Enable brainpool curves for TLS1.3" 
This partially reverts commit 0a10825a0 in order to reimplement it in a
simpler way in the next commit. The reverted aspects are all related to
the TLSv1.3 brainpool curves in the supported_groups extension. Rather
than special casing the handling of these curves we simply add new entries
to the groups table to represent them. They can then be handled without
any additional special casing. This makes the code simpler to maintain.

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Dmitry Belyavskiy <beldmit@gmail.com>
(Merged from https://github.com/openssl/openssl/pull/19315)
2022-10-07 10:01:48 +01:00
..
extensions_clnt.c Partial revert and reimplement "Enable brainpool curves for TLS1.3" 2022-10-07 10:01:48 +01:00
extensions_cust.c SSL object refactoring using SSL_CONNECTION object 2022-07-28 10:04:28 +01:00
extensions_srvr.c Partial revert and reimplement "Enable brainpool curves for TLS1.3" 2022-10-07 10:01:48 +01:00
extensions.c Partial revert and reimplement "Enable brainpool curves for TLS1.3" 2022-10-07 10:01:48 +01:00
README.md ssl: Correct filename in README 2021-09-27 09:39:17 +10:00
statem_clnt.c Stop raising ERR_R_MALLOC_FAILURE in most places 2022-10-05 14:02:03 +02:00
statem_dtls.c Stop raising ERR_R_MALLOC_FAILURE in most places 2022-10-05 14:02:03 +02:00
statem_lib.c Partial revert and reimplement "Enable brainpool curves for TLS1.3" 2022-10-07 10:01:48 +01:00
statem_local.h Test TLS extension ordering 2022-09-28 09:54:25 -04:00
statem_srvr.c Stop raising ERR_R_MALLOC_FAILURE in most places 2022-10-05 14:02:03 +02:00
statem.c Use an enum for the return value from a construction function 2022-09-20 08:16:57 +01:00
statem.h Use an enum for the return value from a construction function 2022-09-20 08:16:57 +01:00

README.md

State Machine Design

This file provides some guidance on the thinking behind the design of the state machine code to aid future maintenance.

The state machine code replaces an older state machine present in OpenSSL versions 1.0.2 and below. The new state machine has the following objectives:

  • Remove duplication of state code between client and server
  • Remove duplication of state code between TLS and DTLS
  • Simplify transitions and bring the logic together in a single location so that it is easier to validate
  • Remove duplication of code between each of the message handling functions
  • Receive a message first and then work out whether that is a valid transition - not the other way around (the other way causes lots of issues where we are expecting one type of message next but actually get something else)
  • Separate message flow state from handshake state (in order to better understand each)
    • message flow state = when to flush buffers; handling restarts in the event of NBIO events; handling the common flow of steps for reading a message and the common flow of steps for writing a message etc
    • handshake state = what handshake message are we working on now
  • Control complexity: only the state machine can change state: keep all the state changes local to the state machine component

The message flow state machine is divided into a reading sub-state machine and a writing sub-state machine. See the source comments in statem.c for a more detailed description of the various states and transitions possible.

Conceptually the state machine component is designed as follows:

                      libssl
                         |
-------------------------|-----statem.h------------------------------------
                         |
                  _______V____________________
                 |                            |
                 |    statem.c                |
                 |                            |
                 |    Core state machine code |
                 |____________________________|
      statem_local.h     ^          ^
               _________|          |_______
              |                            |
 _____________|____________   _____________|____________
|                          | |                          |
| statem_clnt.c            | | statem_srvr.c            |
|                          | |                          |
| TLS/DTLS client specific | | TLS/DTLS server specific |
| state machine code       | | state machine code       |
|__________________________| |__________________________|
             |        |_______________|__       |
             |        ________________|  |      |
             |       |                   |      |
 ____________V_______V________   ________V______V_______________
|                             | |                               |
| statem_lib.c                | | statem_dtls.c                 |
|                             | |                               |
| Non core functions common   | | Non core functions common to  |
| to both servers and clients | | both DTLS servers and clients |
|_____________________________| |_______________________________|