Add initial state machine rewrite code

This is the first drop of the new state machine code.

The rewrite 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 a file

This builds on previous state machine related work:
- Surface CCS processing in the state machine
- Version negotiation rewrite

Reviewed-by: Tim Hudson <tjh@openssl.org>
Reviewed-by: Richard Levitte <levitte@openssl.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/ssl/ssl_err.c b/ssl/ssl_err.c
index 8e95827533..864501b80c 100644
--- a/ssl/ssl_err.c
+++ b/ssl/ssl_err.c
@@ -112,6 +112,7 @@ static ERR_STRING_DATA SSL_str_functs[] = {
     {ERR_FUNC(SSL_F_DTLS1_SEND_SERVER_KEY_EXCHANGE),
      "dtls1_send_server_key_exchange"},
     {ERR_FUNC(SSL_F_DTLS1_WRITE_APP_DATA_BYTES), "dtls1_write_app_data_bytes"},
+    {ERR_FUNC(SSL_F_READ_STATE_MACHINE), "READ_STATE_MACHINE"},
     {ERR_FUNC(SSL_F_SSL3_ACCEPT), "ssl3_accept"},
     {ERR_FUNC(SSL_F_SSL3_ADD_CERT_TO_BUF), "SSL3_ADD_CERT_TO_BUF"},
     {ERR_FUNC(SSL_F_SSL3_CALLBACK_CTRL), "ssl3_callback_ctrl"},
@@ -313,6 +314,7 @@ static ERR_STRING_DATA SSL_str_functs[] = {
     {ERR_FUNC(SSL_F_SSL_USE_RSAPRIVATEKEY_FILE), "SSL_use_RSAPrivateKey_file"},
     {ERR_FUNC(SSL_F_SSL_VERIFY_CERT_CHAIN), "ssl_verify_cert_chain"},
     {ERR_FUNC(SSL_F_SSL_WRITE), "SSL_write"},
+    {ERR_FUNC(SSL_F_STATE_MACHINE), "STATE_MACHINE"},
     {ERR_FUNC(SSL_F_TLS12_CHECK_PEER_SIGALG), "tls12_check_peer_sigalg"},
     {ERR_FUNC(SSL_F_TLS1_CERT_VERIFY_MAC), "tls1_cert_verify_mac"},
     {ERR_FUNC(SSL_F_TLS1_CHANGE_CIPHER_STATE), "tls1_change_cipher_state"},