PSK related tweaks based on review feedback

    }

    cipher = SSL_SESSION_get0_cipher(usesess);

    if (cipher == NULL)

        goto err;

    OPT_DEBUG, OPT_TLSEXTDEBUG, OPT_STATUS, OPT_WDEBUG,

    OPT_MSG, OPT_MSGFILE, OPT_ENGINE, OPT_TRACE, OPT_SECURITY_DEBUG,

    OPT_SECURITY_DEBUG_VERBOSE, OPT_SHOWCERTS, OPT_NBIO_TEST, OPT_STATE,

    OPT_PSK_IDENTITY, OPT_PSK,

    OPT_PSK_SESS,

    OPT_PSK_IDENTITY, OPT_PSK, OPT_PSK_SESS,

#ifndef OPENSSL_NO_SRP

    OPT_SRPUSER, OPT_SRPPASS, OPT_SRP_STRENGTH, OPT_SRP_LATEUSER,

    OPT_SRP_MOREGROUPS,

compatible.

A client application wishing to use PSK ciphersuites for TLSv1.2 and below must

provide a callback function which is called when the client is sending the

ClientKeyExchange message to the server.

provide a callback function. This function will be called when the client is

sending the ClientKeyExchange message to the server.

The purpose of the callback function is to select the PSK identity and

the pre-shared key to use during the connection setup phase.

using either SSL_CTX_set_psk_use_session_callback() or

SSL_set_psk_use_session_callback() as appropriate.

The callback function is given a reference to the SSL connection in B<ssl>.

The callback function is given a pointer to the SSL connection in B<ssl>.

The first time the callback is called for a connection the B<md> parameter is

NULL. In some circumstances the callback will be called a second time. In that

The memory pointed to by B<*id> remains owned by the application and should

be freed by it as required at any point after the handshake is complete.

Additionally the callback should store a reference to an SSL_SESSION object in

Additionally the callback should store a pointer to an SSL_SESSION object in

B<*sess>. This is used as the basis for the PSK, and should, at a minimum, have

the following fields set:

Only the handshake digest associated with the ciphersuite is relevant for the

PSK (the server may go on to negotiate any ciphersuite which is compatible with

the digest). The application can use any TLSv1.3 ciphersuite. Where B<md> is

non-NULL the handshake digest for the ciphersuite should be the same.

the digest). The application can use any TLSv1.3 ciphersuite. If B<md> is

not NULL the handshake digest for the ciphersuite should be the same.

The ciphersuite can be set via a call to <SSL_SESSION_set_cipher(3)>. The

handshake digest of an SSL_CIPHER object can be checked using

<SSL_CIPHER_get_handshake_digest(3)>.

=item The protocol version

This can be set via a call to L<SSL_SESSION_set_protocol_version> and should be

TLS1_3_VERSION.

This can be set via a call to L<SSL_SESSION_set_protocol_version(3)> and should

be TLS1_3_VERSION.

=back

=head1 RETURN VALUES

Return values from the SSL_psk_client_cb_func callback are interpreted as

Return values from the B<SSL_psk_client_cb_func> callback are interpreted as

follows:

On success (callback found a PSK identity and a pre-shared key to use)

Identity hints are not relevant for TLSv1.3. A server application wishing to use

PSK ciphersuites for TLSv1.2 and below may call SSL_CTX_use_psk_identity_hint()

to set the given B<NULL>-terminated PSK identity hint B<hint> for SSL context

object B<ctx>. SSL_use_psk_identity_hint() sets the given B<NULL>-terminated PSK

to set the given B<NUL>-terminated PSK identity hint B<hint> for SSL context

object B<ctx>. SSL_use_psk_identity_hint() sets the given B<NUL>-terminated PSK

identity hint B<hint> for the SSL connection object B<ssl>. If B<hint> is

B<NULL> the current hint from B<ctx> or B<ssl> is deleted.

received PSK identity and to fetch the pre-shared key used during the

connection setup phase. The callback is set using the functions

SSL_CTX_set_psk_server_callback() or SSL_set_psk_server_callback(). The callback

function is given the connection in parameter B<ssl>, B<NULL>-terminated PSK

function is given the connection in parameter B<ssl>, B<NUL>-terminated PSK

identity sent by the client in parameter B<identity>, and a buffer B<psk> of

length B<max_psk_len> bytes where the pre-shared key is to be stored.

using either SSL_CTX_set_psk_use_session_callback() or

SSL_set_psk_use_session_callback() as appropriate.

The callback function is given a reference to the SSL connection in B<ssl> and

The callback function is given a pointer to the SSL connection in B<ssl> and

an identity in B<identity> of length B<identity_len>. The callback function

should identify an SSL_SESSION object that provides the PSK details and store it

in B<*sess>. The SSL_SESSION object should, as a minimum, set the master key,

=head1 RETURN VALUES

SSL_CTX_use_psk_identity_hint() and SSL_use_psk_identity_hint() return

B<SSL_CTX_use_psk_identity_hint()> and B<SSL_use_psk_identity_hint()> return

1 on success, 0 otherwise.

Return values from the TLSv1.2 and below server callback are interpreted as

=back

The SSL_psk_find_session_cb_func callback should return 1 on success or 0 on

The B<SSL_psk_find_session_cb_func> callback should return 1 on success or 0 on

failure. In the event of failure the connection setup fails.

=head1 COPYRIGHT

SSL_SESSION_set1_master_key() sets the master key value associated with the

SSL_SESSION B<sess>. For example, this could be used to set up a session based

PSK (see L<SSL_CTX_set_psk_use_session_callback(3)>). The master key of length

B<len> should be provided at B<in>. A copy of the supplied master key is taken

by the function, so the caller is responsible for freeing and cleaning any

memory associated with B<in>. The caller must ensure that the length of the ke

is suitable for the ciphersuite associated with the SSL_SESSION.

B<len> should be provided at B<in>. The supplied master key is copied by the

function, so the caller is responsible for freeing and cleaning any memory

associated with B<in>. The caller must ensure that the length of the key is

suitable for the ciphersuite associated with the SSL_SESSION.

=head1 NOTES

const EVP_MD *SSL_CIPHER_get_handshake_digest(const SSL_CIPHER *c)

{

    int idx = c->algorithm2;

    int idx = c->algorithm2 & SSL_HANDSHAKE_MAC_MASK;

    idx &= SSL_HANDSHAKE_MAC_MASK;

    if (idx < 0 || idx >= SSL_MD_NUM_IDX)

        return NULL;

    return ssl_digest_methods[idx];