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openssl/ssl/statem/statem.c

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/*
* Copyright 2015-2022 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the Apache License 2.0 (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
*/
#if defined(__TANDEM) && defined(_SPT_MODEL_)
# include <spthread.h>
# include <spt_extensions.h> /* timeval */
#endif
#include "internal/cryptlib.h"
#include <openssl/rand.h>
#include "../ssl_local.h"
#include "statem_local.h"
#include <assert.h>
/*
* This file implements the SSL/TLS/DTLS state machines.
*
* There are two primary state machines:
*
* 1) Message flow state machine
* 2) Handshake state machine
*
* The Message flow state machine controls the reading and sending of messages
* including handling of non-blocking IO events, flushing of the underlying
* write BIO, handling unexpected messages, etc. It is itself broken into two
* separate sub-state machines which control reading and writing respectively.
*
* The Handshake state machine keeps track of the current SSL/TLS handshake
* state. Transitions of the handshake state are the result of events that
* occur within the Message flow state machine.
*
* Overall it looks like this:
*
* --------------------------------------------- -------------------
* | | | |
* | Message flow state machine | | |
* | | | |
* | -------------------- -------------------- | Transition | Handshake state |
* | | MSG_FLOW_READING | | MSG_FLOW_WRITING | | Event | machine |
* | | sub-state | | sub-state | |----------->| |
* | | machine for | | machine for | | | |
* | | reading messages | | writing messages | | | |
* | -------------------- -------------------- | | |
* | | | |
* --------------------------------------------- -------------------
*
*/
/* Sub state machine return values */
typedef enum {
/* Something bad happened or NBIO */
SUB_STATE_ERROR,
/* Sub state finished go to the next sub state */
SUB_STATE_FINISHED,
/* Sub state finished and handshake was completed */
SUB_STATE_END_HANDSHAKE
} SUB_STATE_RETURN;
static int state_machine(SSL_CONNECTION *s, int server);
static void init_read_state_machine(SSL_CONNECTION *s);
static SUB_STATE_RETURN read_state_machine(SSL_CONNECTION *s);
static void init_write_state_machine(SSL_CONNECTION *s);
static SUB_STATE_RETURN write_state_machine(SSL_CONNECTION *s);
OSSL_HANDSHAKE_STATE SSL_get_state(const SSL *ssl)
{
const SSL_CONNECTION *sc = SSL_CONNECTION_FROM_CONST_SSL(ssl);
if (sc == NULL)
return TLS_ST_BEFORE;
return sc->statem.hand_state;
}
int SSL_in_init(const SSL *s)
{
const SSL_CONNECTION *sc = SSL_CONNECTION_FROM_CONST_SSL(s);
if (sc == NULL)
return 0;
return sc->statem.in_init;
}
int SSL_is_init_finished(const SSL *s)
{
const SSL_CONNECTION *sc = SSL_CONNECTION_FROM_CONST_SSL(s);
if (sc == NULL)
return 0;
return !(sc->statem.in_init) && (sc->statem.hand_state == TLS_ST_OK);
}
int SSL_in_before(const SSL *s)
{
const SSL_CONNECTION *sc = SSL_CONNECTION_FROM_CONST_SSL(s);
if (sc == NULL)
return 0;
/*
* Historically being "in before" meant before anything had happened. In the
* current code though we remain in the "before" state for a while after we
* have started the handshake process (e.g. as a server waiting for the
* first message to arrive). There "in before" is taken to mean "in before"
* and not started any handshake process yet.
*/
return (sc->statem.hand_state == TLS_ST_BEFORE)
&& (sc->statem.state == MSG_FLOW_UNINITED);
}
OSSL_HANDSHAKE_STATE ossl_statem_get_state(SSL_CONNECTION *s)
{
return s != NULL ? s->statem.hand_state : TLS_ST_BEFORE;
}
/*
* Clear the state machine state and reset back to MSG_FLOW_UNINITED
*/
void ossl_statem_clear(SSL_CONNECTION *s)
{
s->statem.state = MSG_FLOW_UNINITED;
s->statem.hand_state = TLS_ST_BEFORE;
ossl_statem_set_in_init(s, 1);
s->statem.no_cert_verify = 0;
}
/*
* Set the state machine up ready for a renegotiation handshake
*/
void ossl_statem_set_renegotiate(SSL_CONNECTION *s)
{
ossl_statem_set_in_init(s, 1);
s->statem.request_state = TLS_ST_SW_HELLO_REQ;
}
void ossl_statem_send_fatal(SSL_CONNECTION *s, int al)
{
/* We shouldn't call SSLfatal() twice. Once is enough */
if (s->statem.in_init && s->statem.state == MSG_FLOW_ERROR)
return;
ossl_statem_set_in_init(s, 1);
s->statem.state = MSG_FLOW_ERROR;
if (al != SSL_AD_NO_ALERT)
ssl3_send_alert(s, SSL3_AL_FATAL, al);
}
/*
* Error reporting building block that's used instead of ERR_set_error().
* In addition to what ERR_set_error() does, this puts the state machine
* into an error state and sends an alert if appropriate.
* This is a permanent error for the current connection.
*/
void ossl_statem_fatal(SSL_CONNECTION *s, int al, int reason,
const char *fmt, ...)
{
va_list args;
va_start(args, fmt);
ERR_vset_error(ERR_LIB_SSL, reason, fmt, args);
va_end(args);
ossl_statem_send_fatal(s, al);
}
/*
* This macro should only be called if we are already expecting to be in
* a fatal error state. We verify that we are, and set it if not (this would
* indicate a bug).
*/
#define check_fatal(s) \
do { \
if (!ossl_assert((s)->statem.in_init \
&& (s)->statem.state == MSG_FLOW_ERROR)) \
SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_R_MISSING_FATAL); \
} while (0)
/*
* Discover whether the current connection is in the error state.
*
* Valid return values are:
* 1: Yes
* 0: No
*/
int ossl_statem_in_error(const SSL_CONNECTION *s)
{
if (s->statem.state == MSG_FLOW_ERROR)
return 1;
return 0;
}
void ossl_statem_set_in_init(SSL_CONNECTION *s, int init)
{
s->statem.in_init = init;
if (s->rlayer.rrlmethod != NULL && s->rlayer.rrlmethod->set_in_init != NULL)
s->rlayer.rrlmethod->set_in_init(s->rlayer.rrl, init);
}
int ossl_statem_get_in_handshake(SSL_CONNECTION *s)
{
return s->statem.in_handshake;
}
void ossl_statem_set_in_handshake(SSL_CONNECTION *s, int inhand)
{
if (inhand)
s->statem.in_handshake++;
else
s->statem.in_handshake--;
}
/* Are we in a sensible state to skip over unreadable early data? */
int ossl_statem_skip_early_data(SSL_CONNECTION *s)
{
if (s->ext.early_data != SSL_EARLY_DATA_REJECTED)
return 0;
if (!s->server
|| s->statem.hand_state != TLS_ST_EARLY_DATA
|| s->hello_retry_request == SSL_HRR_COMPLETE)
return 0;
return 1;
}
/*
* Called when we are in SSL_read*(), SSL_write*(), or SSL_accept()
* /SSL_connect()/SSL_do_handshake(). Used to test whether we are in an early
* data state and whether we should attempt to move the handshake on if so.
* |sending| is 1 if we are attempting to send data (SSL_write*()), 0 if we are
* attempting to read data (SSL_read*()), or -1 if we are in SSL_do_handshake()
* or similar.
*/
void ossl_statem_check_finish_init(SSL_CONNECTION *s, int sending)
{
if (sending == -1) {
if (s->statem.hand_state == TLS_ST_PENDING_EARLY_DATA_END
|| s->statem.hand_state == TLS_ST_EARLY_DATA) {
ossl_statem_set_in_init(s, 1);
if (s->early_data_state == SSL_EARLY_DATA_WRITE_RETRY) {
/*
* SSL_connect() or SSL_do_handshake() has been called directly.
* We don't allow any more writing of early data.
*/
s->early_data_state = SSL_EARLY_DATA_FINISHED_WRITING;
}
}
} else if (!s->server) {
if ((sending && (s->statem.hand_state == TLS_ST_PENDING_EARLY_DATA_END
|| s->statem.hand_state == TLS_ST_EARLY_DATA)
&& s->early_data_state != SSL_EARLY_DATA_WRITING)
|| (!sending && s->statem.hand_state == TLS_ST_EARLY_DATA)) {
ossl_statem_set_in_init(s, 1);
/*
* SSL_write() has been called directly. We don't allow any more
* writing of early data.
*/
if (sending && s->early_data_state == SSL_EARLY_DATA_WRITE_RETRY)
s->early_data_state = SSL_EARLY_DATA_FINISHED_WRITING;
}
} else {
if (s->early_data_state == SSL_EARLY_DATA_FINISHED_READING
&& s->statem.hand_state == TLS_ST_EARLY_DATA)
ossl_statem_set_in_init(s, 1);
}
}
void ossl_statem_set_hello_verify_done(SSL_CONNECTION *s)
{
s->statem.state = MSG_FLOW_UNINITED;
ossl_statem_set_in_init(s, 1);
/*
* This will get reset (briefly) back to TLS_ST_BEFORE when we enter
* state_machine() because |state| is MSG_FLOW_UNINITED, but until then any
* calls to SSL_in_before() will return false. Also calls to
* SSL_state_string() and SSL_state_string_long() will return something
* sensible.
*/
s->statem.hand_state = TLS_ST_SR_CLNT_HELLO;
}
int ossl_statem_connect(SSL *s)
{
SSL_CONNECTION *sc = SSL_CONNECTION_FROM_SSL(s);
if (sc == NULL)
return -1;
return state_machine(sc, 0);
}
int ossl_statem_accept(SSL *s)
{
SSL_CONNECTION *sc = SSL_CONNECTION_FROM_SSL(s);
if (sc == NULL)
return -1;
return state_machine(sc, 1);
}
typedef void (*info_cb) (const SSL *, int, int);
static info_cb get_callback(SSL_CONNECTION *s)
{
SSL_CTX *sctx = SSL_CONNECTION_GET_CTX(s);
if (s->info_callback != NULL)
return s->info_callback;
else if (sctx->info_callback != NULL)
return sctx->info_callback;
return NULL;
}
/*
* The main message flow state machine. We start in the MSG_FLOW_UNINITED or
* MSG_FLOW_FINISHED state and finish in MSG_FLOW_FINISHED. Valid states and
* transitions are as follows:
*
* MSG_FLOW_UNINITED MSG_FLOW_FINISHED
* | |
* +-----------------------+
* v
* MSG_FLOW_WRITING <---> MSG_FLOW_READING
* |
* V
* MSG_FLOW_FINISHED
* |
* V
* [SUCCESS]
*
* We may exit at any point due to an error or NBIO event. If an NBIO event
* occurs then we restart at the point we left off when we are recalled.
* MSG_FLOW_WRITING and MSG_FLOW_READING have sub-state machines associated with them.
*
* In addition to the above there is also the MSG_FLOW_ERROR state. We can move
* into that state at any point in the event that an irrecoverable error occurs.
*
* Valid return values are:
* 1: Success
* <=0: NBIO or error
*/
static int state_machine(SSL_CONNECTION *s, int server)
{
BUF_MEM *buf = NULL;
void (*cb) (const SSL *ssl, int type, int val) = NULL;
OSSL_STATEM *st = &s->statem;
int ret = -1;
int ssret;
SSL *ssl = SSL_CONNECTION_GET_SSL(s);
SSL *ussl = SSL_CONNECTION_GET_USER_SSL(s);
if (st->state == MSG_FLOW_ERROR) {
/* Shouldn't have been called if we're already in the error state */
return -1;
}
ERR_clear_error();
clear_sys_error();
cb = get_callback(s);
st->in_handshake++;
if (!SSL_in_init(ssl) || SSL_in_before(ssl)) {
/*
* If we are stateless then we already called SSL_clear() - don't do
* it again and clear the STATELESS flag itself.
*/
if ((s->s3.flags & TLS1_FLAGS_STATELESS) == 0 && !SSL_clear(ssl))
return -1;
}
#ifndef OPENSSL_NO_SCTP
if (SSL_CONNECTION_IS_DTLS(s) && BIO_dgram_is_sctp(SSL_get_wbio(ssl))) {
/*
* Notify SCTP BIO socket to enter handshake mode and prevent stream
* identifier other than 0.
*/
BIO_ctrl(SSL_get_wbio(ssl), BIO_CTRL_DGRAM_SCTP_SET_IN_HANDSHAKE,
st->in_handshake, NULL);
}
#endif
/* Initialise state machine */
if (st->state == MSG_FLOW_UNINITED
|| st->state == MSG_FLOW_FINISHED) {
if (st->state == MSG_FLOW_UNINITED) {
st->hand_state = TLS_ST_BEFORE;
st->request_state = TLS_ST_BEFORE;
}
s->server = server;
if (cb != NULL) {
if (SSL_IS_FIRST_HANDSHAKE(s) || !SSL_CONNECTION_IS_TLS13(s))
cb(ussl, SSL_CB_HANDSHAKE_START, 1);
}
/*
* Fatal errors in this block don't send an alert because we have
* failed to even initialise properly. Sending an alert is probably
* doomed to failure.
*/
if (SSL_CONNECTION_IS_DTLS(s)) {
if ((s->version & 0xff00) != (DTLS1_VERSION & 0xff00) &&
(server || (s->version & 0xff00) != (DTLS1_BAD_VER & 0xff00))) {
SSLfatal(s, SSL_AD_NO_ALERT, ERR_R_INTERNAL_ERROR);
goto end;
}
} else {
if ((s->version >> 8) != SSL3_VERSION_MAJOR) {
SSLfatal(s, SSL_AD_NO_ALERT, ERR_R_INTERNAL_ERROR);
goto end;
}
}
if (!ssl_security(s, SSL_SECOP_VERSION, 0, s->version, NULL)) {
SSLfatal(s, SSL_AD_NO_ALERT, ERR_R_INTERNAL_ERROR);
goto end;
}
if (s->init_buf == NULL) {
if ((buf = BUF_MEM_new()) == NULL) {
SSLfatal(s, SSL_AD_NO_ALERT, ERR_R_INTERNAL_ERROR);
goto end;
}
if (!BUF_MEM_grow(buf, SSL3_RT_MAX_PLAIN_LENGTH)) {
SSLfatal(s, SSL_AD_NO_ALERT, ERR_R_INTERNAL_ERROR);
goto end;
}
s->init_buf = buf;
buf = NULL;
}
s->init_num = 0;
/*
* Should have been reset by tls_process_finished, too.
*/
s->s3.change_cipher_spec = 0;
/*
* Ok, we now need to push on a buffering BIO ...but not with
* SCTP
*/
#ifndef OPENSSL_NO_SCTP
if (!SSL_CONNECTION_IS_DTLS(s) || !BIO_dgram_is_sctp(SSL_get_wbio(ssl)))
#endif
if (!ssl_init_wbio_buffer(s)) {
SSLfatal(s, SSL_AD_NO_ALERT, ERR_R_INTERNAL_ERROR);
goto end;
}
if ((SSL_in_before(ssl))
|| s->renegotiate) {
if (!tls_setup_handshake(s)) {
/* SSLfatal() already called */
goto end;
}
if (SSL_IS_FIRST_HANDSHAKE(s))
st->read_state_first_init = 1;
}
st->state = MSG_FLOW_WRITING;
init_write_state_machine(s);
}
while (st->state != MSG_FLOW_FINISHED) {
if (st->state == MSG_FLOW_READING) {
ssret = read_state_machine(s);
if (ssret == SUB_STATE_FINISHED) {
st->state = MSG_FLOW_WRITING;
init_write_state_machine(s);
} else {
/* NBIO or error */
goto end;
}
} else if (st->state == MSG_FLOW_WRITING) {
ssret = write_state_machine(s);
if (ssret == SUB_STATE_FINISHED) {
st->state = MSG_FLOW_READING;
init_read_state_machine(s);
} else if (ssret == SUB_STATE_END_HANDSHAKE) {
st->state = MSG_FLOW_FINISHED;
} else {
/* NBIO or error */
goto end;
}
} else {
/* Error */
check_fatal(s);
ERR_raise(ERR_LIB_SSL, ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);
goto end;
}
}
ret = 1;
end:
st->in_handshake--;
#ifndef OPENSSL_NO_SCTP
if (SSL_CONNECTION_IS_DTLS(s) && BIO_dgram_is_sctp(SSL_get_wbio(ssl))) {
/*
* Notify SCTP BIO socket to leave handshake mode and allow stream
* identifier other than 0.
*/
BIO_ctrl(SSL_get_wbio(ssl), BIO_CTRL_DGRAM_SCTP_SET_IN_HANDSHAKE,
st->in_handshake, NULL);
}
#endif
BUF_MEM_free(buf);
if (cb != NULL) {
if (server)
cb(ussl, SSL_CB_ACCEPT_EXIT, ret);
else
cb(ussl, SSL_CB_CONNECT_EXIT, ret);
}
return ret;
}
/*
* Initialise the MSG_FLOW_READING sub-state machine
*/
static void init_read_state_machine(SSL_CONNECTION *s)
{
OSSL_STATEM *st = &s->statem;
st->read_state = READ_STATE_HEADER;
}
static int grow_init_buf(SSL_CONNECTION *s, size_t size) {
size_t msg_offset = (char *)s->init_msg - s->init_buf->data;
if (!BUF_MEM_grow_clean(s->init_buf, (int)size))
return 0;
if (size < msg_offset)
return 0;
s->init_msg = s->init_buf->data + msg_offset;
return 1;
}
/*
* This function implements the sub-state machine when the message flow is in
* MSG_FLOW_READING. The valid sub-states and transitions are:
*
* READ_STATE_HEADER <--+<-------------+
* | | |
* v | |
* READ_STATE_BODY -----+-->READ_STATE_POST_PROCESS
* | |
* +----------------------------+
* v
* [SUB_STATE_FINISHED]
*
* READ_STATE_HEADER has the responsibility for reading in the message header
* and transitioning the state of the handshake state machine.
*
* READ_STATE_BODY reads in the rest of the message and then subsequently
* processes it.
*
* READ_STATE_POST_PROCESS is an optional step that may occur if some post
* processing activity performed on the message may block.
*
* Any of the above states could result in an NBIO event occurring in which case
* control returns to the calling application. When this function is recalled we
* will resume in the same state where we left off.
*/
static SUB_STATE_RETURN read_state_machine(SSL_CONNECTION *s)
{
OSSL_STATEM *st = &s->statem;
int ret, mt;
size_t len = 0;
int (*transition) (SSL_CONNECTION *s, int mt);
PACKET pkt;
MSG_PROCESS_RETURN(*process_message) (SSL_CONNECTION *s, PACKET *pkt);
WORK_STATE(*post_process_message) (SSL_CONNECTION *s, WORK_STATE wst);
size_t (*max_message_size) (SSL_CONNECTION *s);
void (*cb) (const SSL *ssl, int type, int val) = NULL;
SSL *ssl = SSL_CONNECTION_GET_USER_SSL(s);
cb = get_callback(s);
if (s->server) {
transition = ossl_statem_server_read_transition;
process_message = ossl_statem_server_process_message;
max_message_size = ossl_statem_server_max_message_size;
post_process_message = ossl_statem_server_post_process_message;
} else {
transition = ossl_statem_client_read_transition;
process_message = ossl_statem_client_process_message;
max_message_size = ossl_statem_client_max_message_size;
post_process_message = ossl_statem_client_post_process_message;
}
if (st->read_state_first_init) {
s->first_packet = 1;
st->read_state_first_init = 0;
}
while (1) {
switch (st->read_state) {
case READ_STATE_HEADER:
/* Get the state the peer wants to move to */
if (SSL_CONNECTION_IS_DTLS(s)) {
/*
* In DTLS we get the whole message in one go - header and body
*/
ret = dtls_get_message(s, &mt);
} else {
ret = tls_get_message_header(s, &mt);
}
if (ret == 0) {
/* Could be non-blocking IO */
return SUB_STATE_ERROR;
}
if (cb != NULL) {
/* Notify callback of an impending state change */
if (s->server)
cb(ssl, SSL_CB_ACCEPT_LOOP, 1);
else
cb(ssl, SSL_CB_CONNECT_LOOP, 1);
}
/*
* Validate that we are allowed to move to the new state and move
* to that state if so
*/
if (!transition(s, mt))
return SUB_STATE_ERROR;
if (s->s3.tmp.message_size > max_message_size(s)) {
SSLfatal(s, SSL_AD_ILLEGAL_PARAMETER,
SSL_R_EXCESSIVE_MESSAGE_SIZE);
return SUB_STATE_ERROR;
}
/* dtls_get_message already did this */
if (!SSL_CONNECTION_IS_DTLS(s)
&& s->s3.tmp.message_size > 0
&& !grow_init_buf(s, s->s3.tmp.message_size
+ SSL3_HM_HEADER_LENGTH)) {
SSLfatal(s, SSL_AD_INTERNAL_ERROR, ERR_R_BUF_LIB);
return SUB_STATE_ERROR;
}
st->read_state = READ_STATE_BODY;
/* Fall through */
case READ_STATE_BODY:
if (SSL_CONNECTION_IS_DTLS(s)) {
/*
* Actually we already have the body, but we give DTLS the
* opportunity to do any further processing.
*/
ret = dtls_get_message_body(s, &len);
} else {
ret = tls_get_message_body(s, &len);
}
if (ret == 0) {
/* Could be non-blocking IO */
return SUB_STATE_ERROR;
}
s->first_packet = 0;
if (!PACKET_buf_init(&pkt, s->init_msg, len)) {
SSLfatal(s, SSL_AD_INTERNAL_ERROR, ERR_R_INTERNAL_ERROR);
return SUB_STATE_ERROR;
}
ret = process_message(s, &pkt);
/* Discard the packet data */
s->init_num = 0;
switch (ret) {
case MSG_PROCESS_ERROR:
check_fatal(s);
return SUB_STATE_ERROR;
case MSG_PROCESS_FINISHED_READING:
if (SSL_CONNECTION_IS_DTLS(s)) {
dtls1_stop_timer(s);
}
return SUB_STATE_FINISHED;
case MSG_PROCESS_CONTINUE_PROCESSING:
st->read_state = READ_STATE_POST_PROCESS;
st->read_state_work = WORK_MORE_A;
break;
default:
st->read_state = READ_STATE_HEADER;
break;
}
break;
case READ_STATE_POST_PROCESS:
st->read_state_work = post_process_message(s, st->read_state_work);
switch (st->read_state_work) {
case WORK_ERROR:
check_fatal(s);
/* Fall through */
case WORK_MORE_A:
case WORK_MORE_B:
case WORK_MORE_C:
return SUB_STATE_ERROR;
case WORK_FINISHED_CONTINUE:
st->read_state = READ_STATE_HEADER;
break;
case WORK_FINISHED_STOP:
if (SSL_CONNECTION_IS_DTLS(s)) {
dtls1_stop_timer(s);
}
return SUB_STATE_FINISHED;
}
break;
default:
/* Shouldn't happen */
SSLfatal(s, SSL_AD_INTERNAL_ERROR, ERR_R_INTERNAL_ERROR);
return SUB_STATE_ERROR;
}
}
}
/*
* Send a previously constructed message to the peer.
*/
static int statem_do_write(SSL_CONNECTION *s)
{
OSSL_STATEM *st = &s->statem;
if (st->hand_state == TLS_ST_CW_CHANGE
|| st->hand_state == TLS_ST_SW_CHANGE) {
if (SSL_CONNECTION_IS_DTLS(s))
return dtls1_do_write(s, SSL3_RT_CHANGE_CIPHER_SPEC);
else
return ssl3_do_write(s, SSL3_RT_CHANGE_CIPHER_SPEC);
} else {
return ssl_do_write(s);
}
}
/*
* Initialise the MSG_FLOW_WRITING sub-state machine
*/
static void init_write_state_machine(SSL_CONNECTION *s)
{
OSSL_STATEM *st = &s->statem;
st->write_state = WRITE_STATE_TRANSITION;
}
/*
* This function implements the sub-state machine when the message flow is in
* MSG_FLOW_WRITING. The valid sub-states and transitions are:
*
* +-> WRITE_STATE_TRANSITION ------> [SUB_STATE_FINISHED]
* | |
* | v
* | WRITE_STATE_PRE_WORK -----> [SUB_STATE_END_HANDSHAKE]
* | |
* | v
* | WRITE_STATE_SEND
* | |
* | v
* | WRITE_STATE_POST_WORK
* | |
* +-------------+
*
* WRITE_STATE_TRANSITION transitions the state of the handshake state machine
* WRITE_STATE_PRE_WORK performs any work necessary to prepare the later
* sending of the message. This could result in an NBIO event occurring in
* which case control returns to the calling application. When this function
* is recalled we will resume in the same state where we left off.
*
* WRITE_STATE_SEND sends the message and performs any work to be done after
* sending.
*
* WRITE_STATE_POST_WORK performs any work necessary after the sending of the
* message has been completed. As for WRITE_STATE_PRE_WORK this could also
* result in an NBIO event.
*/
static SUB_STATE_RETURN write_state_machine(SSL_CONNECTION *s)
{
OSSL_STATEM *st = &s->statem;
int ret;
WRITE_TRAN(*transition) (SSL_CONNECTION *s);
WORK_STATE(*pre_work) (SSL_CONNECTION *s, WORK_STATE wst);
WORK_STATE(*post_work) (SSL_CONNECTION *s, WORK_STATE wst);
int (*get_construct_message_f) (SSL_CONNECTION *s,
CON_FUNC_RETURN (**confunc) (SSL_CONNECTION *s,
WPACKET *pkt),
int *mt);
void (*cb) (const SSL *ssl, int type, int val) = NULL;
CON_FUNC_RETURN (*confunc) (SSL_CONNECTION *s, WPACKET *pkt);
int mt;
WPACKET pkt;
SSL *ssl = SSL_CONNECTION_GET_USER_SSL(s);
cb = get_callback(s);
if (s->server) {
transition = ossl_statem_server_write_transition;
pre_work = ossl_statem_server_pre_work;
post_work = ossl_statem_server_post_work;
get_construct_message_f = ossl_statem_server_construct_message;
} else {
transition = ossl_statem_client_write_transition;
pre_work = ossl_statem_client_pre_work;
post_work = ossl_statem_client_post_work;
get_construct_message_f = ossl_statem_client_construct_message;
}
while (1) {
switch (st->write_state) {
case WRITE_STATE_TRANSITION:
if (cb != NULL) {
/* Notify callback of an impending state change */
if (s->server)
cb(ssl, SSL_CB_ACCEPT_LOOP, 1);
else
cb(ssl, SSL_CB_CONNECT_LOOP, 1);
}
switch (transition(s)) {
case WRITE_TRAN_CONTINUE:
st->write_state = WRITE_STATE_PRE_WORK;
st->write_state_work = WORK_MORE_A;
break;
case WRITE_TRAN_FINISHED:
return SUB_STATE_FINISHED;
break;
case WRITE_TRAN_ERROR:
check_fatal(s);
return SUB_STATE_ERROR;
}
break;
case WRITE_STATE_PRE_WORK:
switch (st->write_state_work = pre_work(s, st->write_state_work)) {
case WORK_ERROR:
check_fatal(s);
/* Fall through */
case WORK_MORE_A:
case WORK_MORE_B:
case WORK_MORE_C:
return SUB_STATE_ERROR;
case WORK_FINISHED_CONTINUE:
st->write_state = WRITE_STATE_SEND;
break;
case WORK_FINISHED_STOP:
return SUB_STATE_END_HANDSHAKE;
}
if (!get_construct_message_f(s, &confunc, &mt)) {
/* SSLfatal() already called */
return SUB_STATE_ERROR;
}
if (mt == SSL3_MT_DUMMY) {
/* Skip construction and sending. This isn't a "real" state */
st->write_state = WRITE_STATE_POST_WORK;
st->write_state_work = WORK_MORE_A;
break;
}
if (!WPACKET_init(&pkt, s->init_buf)
|| !ssl_set_handshake_header(s, &pkt, mt)) {
WPACKET_cleanup(&pkt);
SSLfatal(s, SSL_AD_INTERNAL_ERROR, ERR_R_INTERNAL_ERROR);
return SUB_STATE_ERROR;
}
if (confunc != NULL) {
CON_FUNC_RETURN tmpret;
tmpret = confunc(s, &pkt);
if (tmpret == CON_FUNC_ERROR) {
WPACKET_cleanup(&pkt);
check_fatal(s);
return SUB_STATE_ERROR;
} else if (tmpret == CON_FUNC_DONT_SEND) {
/*
* The construction function decided not to construct the
* message after all and continue. Skip sending.
*/
WPACKET_cleanup(&pkt);
st->write_state = WRITE_STATE_POST_WORK;
st->write_state_work = WORK_MORE_A;
break;
} /* else success */
}
if (!ssl_close_construct_packet(s, &pkt, mt)
|| !WPACKET_finish(&pkt)) {
WPACKET_cleanup(&pkt);
SSLfatal(s, SSL_AD_INTERNAL_ERROR, ERR_R_INTERNAL_ERROR);
return SUB_STATE_ERROR;
}
/* Fall through */
case WRITE_STATE_SEND:
if (SSL_CONNECTION_IS_DTLS(s) && st->use_timer) {
dtls1_start_timer(s);
}
ret = statem_do_write(s);
if (ret <= 0) {
return SUB_STATE_ERROR;
}
st->write_state = WRITE_STATE_POST_WORK;
st->write_state_work = WORK_MORE_A;
/* Fall through */
case WRITE_STATE_POST_WORK:
switch (st->write_state_work = post_work(s, st->write_state_work)) {
case WORK_ERROR:
check_fatal(s);
/* Fall through */
case WORK_MORE_A:
case WORK_MORE_B:
case WORK_MORE_C:
return SUB_STATE_ERROR;
case WORK_FINISHED_CONTINUE:
st->write_state = WRITE_STATE_TRANSITION;
break;
case WORK_FINISHED_STOP:
return SUB_STATE_END_HANDSHAKE;
}
break;
default:
SSLfatal(s, SSL_AD_INTERNAL_ERROR, ERR_R_INTERNAL_ERROR);
return SUB_STATE_ERROR;
}
}
}
/*
* Flush the write BIO
*/
int statem_flush(SSL_CONNECTION *s)
{
s->rwstate = SSL_WRITING;
if (BIO_flush(s->wbio) <= 0) {
return 0;
}
s->rwstate = SSL_NOTHING;
return 1;
}
/*
* Called by the record layer to determine whether application data is
* allowed to be received in the current handshake state or not.
*
* Return values are:
* 1: Yes (application data allowed)
* 0: No (application data not allowed)
*/
int ossl_statem_app_data_allowed(SSL_CONNECTION *s)
{
OSSL_STATEM *st = &s->statem;
if (st->state == MSG_FLOW_UNINITED)
return 0;
if (!s->s3.in_read_app_data || (s->s3.total_renegotiations == 0))
return 0;
if (s->server) {
/*
* If we're a server and we haven't got as far as writing our
* ServerHello yet then we allow app data
*/
if (st->hand_state == TLS_ST_BEFORE
|| st->hand_state == TLS_ST_SR_CLNT_HELLO)
return 1;
} else {
/*
* If we're a client and we haven't read the ServerHello yet then we
* allow app data
*/
if (st->hand_state == TLS_ST_CW_CLNT_HELLO)
return 1;
}
return 0;
}
/*
* This function returns 1 if TLS exporter is ready to export keying
* material, or 0 if otherwise.
*/
int ossl_statem_export_allowed(SSL_CONNECTION *s)
{
return s->s3.previous_server_finished_len != 0
&& s->statem.hand_state != TLS_ST_SW_FINISHED;
}
/*
* Return 1 if early TLS exporter is ready to export keying material,
* or 0 if otherwise.
*/
int ossl_statem_export_early_allowed(SSL_CONNECTION *s)
{
/*
* The early exporter secret is only present on the server if we
* have accepted early_data. It is present on the client as long
* as we have sent early_data.
*/
return s->ext.early_data == SSL_EARLY_DATA_ACCEPTED
|| (!s->server && s->ext.early_data != SSL_EARLY_DATA_NOT_SENT);
}
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