/*
 * Copyright 2015-2016 The OpenSSL Project Authors. All Rights Reserved.
 *
 * Licensed under the OpenSSL license (the "License").  You may not use
 * this file except in compliance with the License.  You can obtain a copy
 * in the file LICENSE in the source distribution or at
 * https://www.openssl.org/source/license.html
 */

/*****************************************************************************
 *                                                                           *
 * The following definitions are PRIVATE to the state machine. They should   *
 * NOT be used outside of the state machine.                                 *
 *                                                                           *
 *****************************************************************************/

/* Max message length definitions */

/* The spec allows for a longer length than this, but we limit it */
#define HELLO_VERIFY_REQUEST_MAX_LENGTH 258
#define SERVER_HELLO_MAX_LENGTH         20000
#define ENCRYPTED_EXTENSIONS_MAX_LENGTH 20000
#define SERVER_KEY_EXCH_MAX_LENGTH      102400
#define SERVER_HELLO_DONE_MAX_LENGTH    0
#define CCS_MAX_LENGTH                  1
/* Max should actually be 36 but we are generous */
#define FINISHED_MAX_LENGTH             64

/* Extension context codes */
#define EXT_TLS_ONLY                        0x0001
#define EXT_DTLS_ONLY                       0x0002
/* Some extensions may be allowed in DTLS but we don't implement them for it */
#define EXT_TLS_IMPLEMENTATION_ONLY         0x0004
/* Most extensions are not defined for SSLv3 but EXT_TYPE_renegotiate is */
#define EXT_SSL3_ALLOWED                    0x0008
#define EXT_TLS1_2_AND_BELOW_ONLY           0x0010
#define EXT_TLS1_3_ONLY                     0x0020
#define EXT_CLIENT_HELLO                    0x0040
/* Really means TLS1.2 or below */
#define EXT_TLS1_2_SERVER_HELLO             0x0080
#define EXT_TLS1_3_SERVER_HELLO             0x0100
#define EXT_TLS1_3_ENCRYPTED_EXTENSIONS     0x0200
#define EXT_TLS1_3_HELLO_RETRY_REQUEST      0x0400
#define EXT_TLS1_3_CERTIFICATE              0x0800
#define EXT_TLS1_3_NEW_SESSION_TICKET       0x1000

/* Message processing return codes */
typedef enum {
    /* Something bad happened */
    MSG_PROCESS_ERROR,
    /* We've finished reading - swap to writing */
    MSG_PROCESS_FINISHED_READING,
    /*
     * We've completed the main processing of this message but there is some
     * post processing to be done.
     */
    MSG_PROCESS_CONTINUE_PROCESSING,
    /* We've finished this message - read the next message */
    MSG_PROCESS_CONTINUE_READING
} MSG_PROCESS_RETURN;

/* Flush the write BIO */
int statem_flush(SSL *s);

typedef int (*confunc_f) (SSL *s, WPACKET *pkt);

/*
 * TLS/DTLS client state machine functions
 */
int ossl_statem_client_read_transition(SSL *s, int mt);
WRITE_TRAN ossl_statem_client_write_transition(SSL *s);
WORK_STATE ossl_statem_client_pre_work(SSL *s, WORK_STATE wst);
WORK_STATE ossl_statem_client_post_work(SSL *s, WORK_STATE wst);
int ossl_statem_client_construct_message(SSL *s, WPACKET *pkt,
                                         confunc_f *confunc, int *mt);
size_t ossl_statem_client_max_message_size(SSL *s);
MSG_PROCESS_RETURN ossl_statem_client_process_message(SSL *s, PACKET *pkt);
WORK_STATE ossl_statem_client_post_process_message(SSL *s, WORK_STATE wst);

/*
 * TLS/DTLS server state machine functions
 */
int ossl_statem_server_read_transition(SSL *s, int mt);
WRITE_TRAN ossl_statem_server_write_transition(SSL *s);
WORK_STATE ossl_statem_server_pre_work(SSL *s, WORK_STATE wst);
WORK_STATE ossl_statem_server_post_work(SSL *s, WORK_STATE wst);
int ossl_statem_server_construct_message(SSL *s, WPACKET *pkt,
                                         confunc_f *confunc,int *mt);
size_t ossl_statem_server_max_message_size(SSL *s);
MSG_PROCESS_RETURN ossl_statem_server_process_message(SSL *s, PACKET *pkt);
WORK_STATE ossl_statem_server_post_process_message(SSL *s, WORK_STATE wst);

/* Functions for getting new message data */
__owur int tls_get_message_header(SSL *s, int *mt);
__owur int tls_get_message_body(SSL *s, size_t *len);
__owur int dtls_get_message(SSL *s, int *mt, size_t *len);

/* Message construction and processing functions */
__owur int tls_process_initial_server_flight(SSL *s, int *al);
__owur MSG_PROCESS_RETURN tls_process_change_cipher_spec(SSL *s, PACKET *pkt);
__owur MSG_PROCESS_RETURN tls_process_finished(SSL *s, PACKET *pkt);
__owur int tls_construct_change_cipher_spec(SSL *s, WPACKET *pkt);
__owur int dtls_construct_change_cipher_spec(SSL *s, WPACKET *pkt);

__owur int tls_construct_finished(SSL *s, WPACKET *pkt);
__owur WORK_STATE tls_finish_handshake(SSL *s, WORK_STATE wst);
__owur WORK_STATE dtls_wait_for_dry(SSL *s);

int tls_collect_extensions(SSL *s, PACKET *packet, unsigned int context,
                           RAW_EXTENSION **res, size_t *numfound, int *ad);

/* some client-only functions */
__owur int tls_construct_client_hello(SSL *s, WPACKET *pkt);
__owur MSG_PROCESS_RETURN tls_process_server_hello(SSL *s, PACKET *pkt);
__owur MSG_PROCESS_RETURN tls_process_certificate_request(SSL *s, PACKET *pkt);
__owur MSG_PROCESS_RETURN tls_process_new_session_ticket(SSL *s, PACKET *pkt);
__owur MSG_PROCESS_RETURN tls_process_cert_status(SSL *s, PACKET *pkt);
__owur MSG_PROCESS_RETURN tls_process_server_done(SSL *s, PACKET *pkt);
__owur int tls_construct_client_verify(SSL *s, WPACKET *pkt);
__owur WORK_STATE tls_prepare_client_certificate(SSL *s, WORK_STATE wst);
__owur int tls_construct_client_certificate(SSL *s, WPACKET *pkt);
__owur int ssl_do_client_cert_cb(SSL *s, X509 **px509, EVP_PKEY **ppkey);
__owur int tls_construct_client_key_exchange(SSL *s, WPACKET *pkt);
__owur int tls_client_key_exchange_post_work(SSL *s);
__owur int tls_construct_cert_status(SSL *s, WPACKET *pkt);
__owur MSG_PROCESS_RETURN tls_process_key_exchange(SSL *s, PACKET *pkt);
__owur MSG_PROCESS_RETURN tls_process_server_certificate(SSL *s, PACKET *pkt);
__owur int ssl3_check_cert_and_algorithm(SSL *s);
#ifndef OPENSSL_NO_NEXTPROTONEG
__owur int tls_construct_next_proto(SSL *s, WPACKET *pkt);
#endif
__owur MSG_PROCESS_RETURN dtls_process_hello_verify(SSL *s, PACKET *pkt);

/* some server-only functions */
__owur MSG_PROCESS_RETURN tls_process_client_hello(SSL *s, PACKET *pkt);
__owur WORK_STATE tls_post_process_client_hello(SSL *s, WORK_STATE wst);
__owur int tls_construct_server_hello(SSL *s, WPACKET *pkt);
__owur int dtls_construct_hello_verify_request(SSL *s, WPACKET *pkt);
__owur int tls_construct_server_certificate(SSL *s, WPACKET *pkt);
__owur int tls_construct_server_key_exchange(SSL *s, WPACKET *pkt);
__owur int tls_construct_certificate_request(SSL *s, WPACKET *pkt);
__owur int tls_construct_server_done(SSL *s, WPACKET *pkt);
__owur MSG_PROCESS_RETURN tls_process_client_certificate(SSL *s, PACKET *pkt);
__owur MSG_PROCESS_RETURN tls_process_client_key_exchange(SSL *s, PACKET *pkt);
__owur WORK_STATE tls_post_process_client_key_exchange(SSL *s, WORK_STATE wst);
__owur MSG_PROCESS_RETURN tls_process_cert_verify(SSL *s, PACKET *pkt);
#ifndef OPENSSL_NO_NEXTPROTONEG
__owur MSG_PROCESS_RETURN tls_process_next_proto(SSL *s, PACKET *pkt);
#endif
__owur int tls_construct_new_session_ticket(SSL *s, WPACKET *pkt);

__owur int tls_parse_all_extensions(SSL *s, int context, RAW_EXTENSION *exts,
                                    size_t numexts, int *al);
__owur int tls_parse_extension(SSL *s, int type, int context, RAW_EXTENSION *exts,
                               size_t numexts, int *al);
__owur int tls_construct_extensions(SSL *s, WPACKET *pkt, unsigned int context,
                                    int *al);