=pod

=head1 NAME

OSSL_CMP_CTX_new,
OSSL_CMP_CTX_free,
OSSL_CMP_CTX_reinit,
OSSL_CMP_CTX_set_option,
OSSL_CMP_CTX_get_option,
OSSL_CMP_CTX_set_log_cb,
OSSL_CMP_CTX_set_log_verbosity,
OSSL_CMP_CTX_print_errors,
OSSL_CMP_CTX_set1_serverPath,
OSSL_CMP_CTX_set1_serverName,
OSSL_CMP_CTX_set_serverPort,
OSSL_CMP_CTX_set1_proxyName,
OSSL_CMP_CTX_set_proxyPort,
OSSL_CMP_DEFAULT_PORT,
OSSL_cmp_http_cb_t,
OSSL_CMP_CTX_set_http_cb,
OSSL_CMP_CTX_set_http_cb_arg,
OSSL_CMP_CTX_get_http_cb_arg,
OSSL_cmp_transfer_cb_t,
OSSL_CMP_CTX_set_transfer_cb,
OSSL_CMP_CTX_set_transfer_cb_arg,
OSSL_CMP_CTX_get_transfer_cb_arg,
OSSL_CMP_CTX_set1_srvCert,
OSSL_CMP_CTX_set1_expected_sender,
OSSL_CMP_CTX_set0_trustedStore,
OSSL_CMP_CTX_get0_trustedStore,
OSSL_CMP_CTX_set1_untrusted_certs,
OSSL_CMP_CTX_get0_untrusted_certs,
OSSL_CMP_CTX_set1_clCert,
OSSL_CMP_CTX_set1_pkey,
OSSL_CMP_CTX_set1_referenceValue,
OSSL_CMP_CTX_set1_secretValue,
OSSL_CMP_CTX_set1_recipient,
OSSL_CMP_CTX_push0_geninfo_ITAV,
OSSL_CMP_CTX_set1_extraCertsOut,
OSSL_CMP_CTX_set0_newPkey,
OSSL_CMP_CTX_get0_newPkey,
OSSL_CMP_CTX_set1_issuer,
OSSL_CMP_CTX_set1_subjectName,
OSSL_CMP_CTX_push1_subjectAltName,
OSSL_CMP_CTX_set0_reqExtensions,
OSSL_CMP_CTX_reqExtensions_have_SAN,
OSSL_CMP_CTX_push0_policy,
OSSL_CMP_CTX_set1_oldCert,
OSSL_CMP_CTX_set1_p10CSR,
OSSL_CMP_CTX_push0_genm_ITAV,
OSSL_cmp_certConf_cb_t,
OSSL_CMP_CTX_set_certConf_cb,
OSSL_CMP_CTX_set_certConf_cb_arg,
OSSL_CMP_CTX_get_certConf_cb_arg,
OSSL_CMP_CTX_get_status,
OSSL_CMP_CTX_get0_statusString,
OSSL_CMP_CTX_get_failInfoCode,
OSSL_CMP_CTX_get0_newCert,
OSSL_CMP_CTX_get1_caPubs,
OSSL_CMP_CTX_get1_extraCertsIn,
OSSL_CMP_CTX_set1_transactionID,
OSSL_CMP_CTX_set1_senderNonce
- functions for managing the CMP client context data structure

=head1 SYNOPSIS

 #include <openssl/cmp.h>

 OSSL_CMP_CTX *OSSL_CMP_CTX_new(void);
 void OSSL_CMP_CTX_free(OSSL_CMP_CTX *ctx);
 int OSSL_CMP_CTX_reinit(OSSL_CMP_CTX *ctx);
 int OSSL_CMP_CTX_set_option(OSSL_CMP_CTX *ctx, int opt, int val);
 int OSSL_CMP_CTX_get_option(const OSSL_CMP_CTX *ctx, int opt);

 /* logging and error reporting: */
 int OSSL_CMP_CTX_set_log_cb(OSSL_CMP_CTX *ctx, OSSL_cmp_log_cb_t cb);
 #define OSSL_CMP_CTX_set_log_verbosity(ctx, level)
 void OSSL_CMP_CTX_print_errors(OSSL_CMP_CTX *ctx);

 /* message transfer: */
 int OSSL_CMP_CTX_set1_serverPath(OSSL_CMP_CTX *ctx, const char *path);
 int OSSL_CMP_CTX_set1_serverName(OSSL_CMP_CTX *ctx, const char *name);
 int OSSL_CMP_CTX_set_serverPort(OSSL_CMP_CTX *ctx, int port);
 int OSSL_CMP_CTX_set1_proxyName(OSSL_CMP_CTX *ctx, const char *name);
 int OSSL_CMP_CTX_set_proxyPort(OSSL_CMP_CTX *ctx, int port);
 #define OSSL_CMP_DEFAULT_PORT 80
 typedef BIO *(*OSSL_cmp_http_cb_t)(OSSL_CMP_CTX *ctx, BIO *hbio,
                                    unsigned long detail);
 int OSSL_CMP_CTX_set_http_cb(OSSL_CMP_CTX *ctx, OSSL_cmp_http_cb_t cb);
 int OSSL_CMP_CTX_set_http_cb_arg(OSSL_CMP_CTX *ctx, void *arg);
 void *OSSL_CMP_CTX_get_http_cb_arg(const OSSL_CMP_CTX *ctx);
 typedef int (*OSSL_cmp_transfer_cb_t)(OSSL_CMP_CTX *ctx,
                                       const OSSL_CMP_MSG *req,
                                       OSSL_CMP_MSG **res);
 int OSSL_CMP_CTX_set_transfer_cb(OSSL_CMP_CTX *ctx,
                                  OSSL_cmp_transfer_cb_t cb);
 int OSSL_CMP_CTX_set_transfer_cb_arg(OSSL_CMP_CTX *ctx, void *arg);
 void *OSSL_CMP_CTX_get_transfer_cb_arg(const OSSL_CMP_CTX *ctx);

 /* server authentication: */
 int OSSL_CMP_CTX_set1_srvCert(OSSL_CMP_CTX *ctx, X509 *cert);
 int OSSL_CMP_CTX_set1_expected_sender(OSSL_CMP_CTX *ctx,
                                      const X509_NAME *name);
 int OSSL_CMP_CTX_set0_trustedStore(OSSL_CMP_CTX *ctx, X509_STORE *store);
 X509_STORE *OSSL_CMP_CTX_get0_trustedStore(const OSSL_CMP_CTX *ctx);
 int OSSL_CMP_CTX_set1_untrusted_certs(OSSL_CMP_CTX *ctx,
                                       STACK_OF(X509) *certs);
 STACK_OF(X509) *OSSL_CMP_CTX_get0_untrusted_certs(const OSSL_CMP_CTX *ctx);

 /* client authentication: */
 int OSSL_CMP_CTX_set1_clCert(OSSL_CMP_CTX *ctx, X509 *cert);
 int OSSL_CMP_CTX_set1_pkey(OSSL_CMP_CTX *ctx, EVP_PKEY *pkey);
 int OSSL_CMP_CTX_set1_referenceValue(OSSL_CMP_CTX *ctx,
                                      const unsigned char *ref, int len);
 int OSSL_CMP_CTX_set1_secretValue(OSSL_CMP_CTX *ctx, const unsigned char *sec,
                                   const int len);

 /* CMP message header and extra certificates: */
 int OSSL_CMP_CTX_set1_recipient(OSSL_CMP_CTX *ctx, const X509_NAME *name);
 int OSSL_CMP_CTX_push0_geninfo_ITAV(OSSL_CMP_CTX *ctx, OSSL_CMP_ITAV *itav);
 int OSSL_CMP_CTX_set1_extraCertsOut(OSSL_CMP_CTX *ctx,
                                     STACK_OF(X509) *extraCertsOut);

 /* certificate template: */
 int OSSL_CMP_CTX_set0_newPkey(OSSL_CMP_CTX *ctx, int priv, EVP_PKEY *pkey);
 EVP_PKEY *OSSL_CMP_CTX_get0_newPkey(const OSSL_CMP_CTX *ctx, int priv);
 int OSSL_CMP_CTX_set1_issuer(OSSL_CMP_CTX *ctx, const X509_NAME *name);
 int OSSL_CMP_CTX_set1_subjectName(OSSL_CMP_CTX *ctx, const X509_NAME *name);
 int OSSL_CMP_CTX_push1_subjectAltName(OSSL_CMP_CTX *ctx,
                                       const GENERAL_NAME *name);
 int OSSL_CMP_CTX_set0_reqExtensions(OSSL_CMP_CTX *ctx, X509_EXTENSIONS *exts);
 int OSSL_CMP_CTX_reqExtensions_have_SAN(OSSL_CMP_CTX *ctx);
 int OSSL_CMP_CTX_push0_policy(OSSL_CMP_CTX *ctx, POLICYINFO *pinfo);
 int OSSL_CMP_CTX_set1_oldCert(OSSL_CMP_CTX *ctx, X509 *cert);
 int OSSL_CMP_CTX_set1_p10CSR(OSSL_CMP_CTX *ctx, const X509_REQ *csr);

 /* misc body contents: */
 int OSSL_CMP_CTX_push0_genm_ITAV(OSSL_CMP_CTX *ctx, OSSL_CMP_ITAV *itav);

 /* certificate confirmation: */
 typedef int (*OSSL_cmp_certConf_cb_t)(OSSL_CMP_CTX *ctx, X509 *cert,
                                       int fail_info, const char **txt);
 int OSSL_CMP_CTX_set_certConf_cb(OSSL_CMP_CTX *ctx, OSSL_cmp_certConf_cb_t cb);
 int OSSL_CMP_CTX_set_certConf_cb_arg(OSSL_CMP_CTX *ctx, void *arg);
 void *OSSL_CMP_CTX_get_certConf_cb_arg(const OSSL_CMP_CTX *ctx);

 /* result fetching: */
 int OSSL_CMP_CTX_get_status(const OSSL_CMP_CTX *ctx);
 OSSL_CMP_PKIFREETEXT *OSSL_CMP_CTX_get0_statusString(const OSSL_CMP_CTX *ctx);
 int OSSL_CMP_CTX_get_failInfoCode(const OSSL_CMP_CTX *ctx);

 X509 *OSSL_CMP_CTX_get0_newCert(const OSSL_CMP_CTX *ctx);
 STACK_OF(X509) *OSSL_CMP_CTX_get1_caPubs(const OSSL_CMP_CTX *ctx);
 STACK_OF(X509) *OSSL_CMP_CTX_get1_extraCertsIn(const OSSL_CMP_CTX *ctx);

 /* for test purposes only: */
 int OSSL_CMP_CTX_set1_transactionID(OSSL_CMP_CTX *ctx,
                                     const ASN1_OCTET_STRING *id);
 int OSSL_CMP_CTX_set1_senderNonce(OSSL_CMP_CTX *ctx,
                                   const ASN1_OCTET_STRING *nonce);

=head1 DESCRIPTION

This is the context API for using CMP (Certificate Management Protocol) with
OpenSSL.

OSSL_CMP_CTX_new() allocates and initializes an OSSL_CMP_CTX structure to
default values, e.g., proof-of-possession method is set to POPOSigningKey.

OSSL_CMP_CTX_free() deallocates an OSSL_CMP_CTX structure.

OSSL_CMP_CTX_reinit() prepares the given B<ctx> for a further transaction by
clearing the internal CMP transaction (aka session) status, PKIStatusInfo,
and any previous results (newCert, caPubs, and extraCertsIn)
from the last executed transaction.
All other field values (i.e., CMP options) are retained for potential re-use.

OSSL_CMP_CTX_set_option() sets the given value for the given option
(e.g., OSSL_CMP_OPT_IMPLICITCONFIRM) in the given OSSL_CMP_CTX structure.

The following options can be set:

=over 4

=item B<OSSL_CMP_OPT_LOG_VERBOSITY>

        The level of severity needed for actually outputting log messages
        due to errors, warnings, general info, debugging, etc.
        Default is OSSL_CMP_LOG_INFO. See also L<OSSL_CMP_log_open(3)>.

=item B<OSSL_CMP_OPT_MSGTIMEOUT>

        Number of seconds (or 0 for infinite) a CMP message round trip is
        allowed to take before a timeout error is returned. Default is 120.

=item B<OSSL_CMP_OPT_TOTALTIMEOUT>

        Maximum total number of seconds an enrollment (including polling)
        may take. Default is 0 (infinite).

=item B<OSSL_CMP_OPT_VALIDITYDAYS>

        Number of days new certificates are asked to be valid for.

=item B<OSSL_CMP_OPT_SUBJECTALTNAME_NODEFAULT>

        Do not take default Subject Alternative Names
        from the reference certificate.

=item B<OSSL_CMP_OPT_SUBJECTALTNAME_CRITICAL>

        Demand that the given Subject Alternative Names are flagged as critical.

=item B<OSSL_CMP_OPT_POLICIES_CRITICAL>

        Demand that the given policies are flagged as critical.

=item B<OSSL_CMP_OPT_POPOMETHOD>

        Select the proof of possession method to use. Possible values are:

            OSSL_CRMF_POPO_NONE       - ProofOfPossession field omitted
            OSSL_CRMF_POPO_RAVERIFIED - assert that the RA has already
                                        verified the PoPo
            OSSL_CRMF_POPO_SIGNATURE  - sign a value with private key,
                                        which is the default.
            OSSL_CRMF_POPO_KEYENC     - decrypt the encrypted certificate
                                        ("indirect method")

        Note that a signature-based POPO can only be produced if a private key
        is provided as the newPkey or client pkey component of the CMP context.

=item B<OSSL_CMP_OPT_DIGEST_ALGNID>

        The digest algorithm NID to be used in RFC 4210's MSG_SIG_ALG,
        if applicable used for message protection and Proof-of-Possession.
        Default is SHA256.

    OSSL_CMP_OPT_OWF_ALGNID
        The digest algorithm NID to be used as one-way function (OWF)
        in RFC 4210's MSG_MAC_ALG, if applicable used for message protection.
        Default is SHA256.

    OSSL_CMP_OPT_MAC_ALGNID
        The MAC algorithm NID to be used in RFC 4210's MSG_MAC_ALG,
        if applicable used for message protection. 
        Default is HMAC-SHA1 as per RFC 4210.

=item B<OSSL_CMP_OPT_REVOCATION_REASON>

        The reason code to be included in a Revocation Request (RR);
        values: 0..10 (RFC 5210, 5.3.1) or -1 for none, which is the default.

=item B<OSSL_CMP_OPT_IMPLICITCONFIRM>

        Request server to enable implicit confirm mode, where the client
        does not need to send confirmation upon receiving the
        certificate. If the server does not enable implicit confirmation
        in the return message, then confirmation is sent anyway.

=item B<OSSL_CMP_OPT_DISABLECONFIRM>

        Do not confirm enrolled certificates, to cope with broken servers
        not supporting implicit confirmation correctly.
B<WARNING:> This setting leads to unspecified behavior and it is meant
exclusively to allow interoperability with server implementations violating
RFC 4210.

=item B<OSSL_CMP_OPT_UNPROTECTED_SEND>

        Send messages without CMP-level protection.

=item B<OSSL_CMP_OPT_UNPROTECTED_ERRORS>

        Accept unprotected error responses which are either explicitly
        unprotected or where protection verification failed. Applies to regular
        error messages as well as certificate responses (IP/CP/KUP) and
        revocation responses (RP) with rejection.
B<WARNING:> This setting leads to unspecified behavior and it is meant
exclusively to allow interoperability with server implementations violating
RFC 4210.

=item B<OSSL_CMP_OPT_IGNORE_KEYUSAGE>

        Ignore key usage restrictions in signer certificate when
        validating signature-based protection in received CMP messages.
        Else, 'digitalSignature' must be allowed by CMP signer certificates.

=item B<OSSL_CMP_OPT_PERMIT_TA_IN_EXTRACERTS_FOR_IR>

        Allow retrieving a trust anchor from extraCerts and using that
        to validate the certificate chain of an IP message.

=back

OSSL_CMP_CTX_get_option() reads the current value of the given option
(e.g., OSSL_CMP_OPT_IMPLICITCONFIRM) from the given OSSL_CMP_CTX structure.

OSSL_CMP_CTX_set_log_cb() sets in B<ctx> the callback function C<cb>
for handling error queue entries and logging messages.
When C<cb> is NULL errors are printed to STDERR (if available, else ignored)
any log messages are ignored.
Alternatively, L<OSSL_CMP_log_open(3)> may be used to direct logging to STDOUT.

OSSL_CMP_CTX_set_log_verbosity() is a macro setting the
OSSL_CMP_OPT_LOG_VERBOSITY context option to the given level.

OSSL_CMP_CTX_print_errors() outputs any entries in the OpenSSL error queue.
It is similar to B<ERR_print_errors_cb()> but uses the CMP log callback function
if set in the C<ctx> for uniformity with CMP logging if given. Otherwise it uses
B<ERR_print_errors(3)> to print to STDERR (unless OPENSSL_NO_STDIO is defined).

OSSL_CMP_CTX_set1_serverPath() sets the HTTP path of the CMP server on the host.

OSSL_CMP_CTX_set1_serverName() sets the given server Address (as IP or name)
in the given OSSL_CMP_CTX structure.

OSSL_CMP_CTX_set_serverPort() sets the port of the CMP server to connect to.
Port defaults to OSSL_CMP_DEFAULT_PORT = 80 if not set explicitly.

OSSL_CMP_CTX_set1_proxyName() sets the hostname of the HTTP proxy to be used
for connecting to the CA server.

OSSL_CMP_CTX_set_proxyPort() sets the port of the HTTP proxy.
Port defaults to OSSL_CMP_DEFAULT_PORT = 80 if not set explicitly.

OSSL_CMP_CTX_set_http_cb() sets the optional http connect/disconnect callback
function, which has the prototype

 typedef BIO *(*OSSL_cmp_http_cb_t)(OSSL_CMP_CTX *ctx, BIO *hbio,
                                    unsigned long detail);

It may modify the HTTP BIO given in the B<hbio> argument
used by OSSL_CMP_MSG_http_perform().
On connect the B<detail> argument is 1.
On disconnect it is 0 if no error occurred or else the last error code.
For instance, on connect a TLS BIO may be prepended to implement HTTPS,
and on disconnect some error diagnostics and/or cleanup may be done.
The callback function should return NULL to indicate failure.
It may make use of a custom defined argument stored in the ctx
by means of OSSL_CMP_CTX_set_http_cb_arg(),
which may be retrieved again through OSSL_CMP_CTX_get_http_cb_arg().

OSSL_CMP_CTX_set_http_cb_arg() sets an argument, respectively a pointer to
a structure containing arguments,
optionally to be used by the http connect/disconnect callback function.
B<arg> is not consumed, and it must therefore explicitly be freed when not
needed any more. B<arg> may be NULL to clear the entry.

OSSL_CMP_CTX_get_http_cb_arg() gets the argument, respectively the pointer to a
structure containing arguments, previously set by
OSSL_CMP_CTX_set_http_cb_arg() or NULL if unset.

OSSL_CMP_CTX_set_transfer_cb() sets the message transfer callback function,
which has the type

 typedef int (*OSSL_cmp_transfer_cb_t)(const OSSL_CMP_CTX *ctx,
                                       const OSSL_CMP_MSG *req,
                                       OSSL_CMP_MSG **res);
Returns 1 on success, 0 on error.

Default is NULL, which implies the use of L<OSSL_CMP_MSG_http_perform(3)>.
The callback should send the CMP request it obtains via the B<req> parameter
and on success place the response in the B<*res> output parameter.
The transfer callback may make use of a custom defined argument stored in
the ctx by means of OSSL_CMP_CTX_set_transfer_cb_arg(), which may be retrieved
again through OSSL_CMP_CTX_get_transfer_cb_arg().
On success the cb must return 0, else a CMP error reason code defined in cmp.h.


OSSL_CMP_CTX_set_transfer_cb_arg() sets an argument, respectively a pointer to a
structure containing arguments, optionally to be used by the transfer callback.
B<arg> is not consumed, and it must therefore explicitly be freed when not
needed any more. B<arg> may be NULL to clear the entry.

OSSL_CMP_CTX_get_transfer_cb_arg() gets the argument, respectively the pointer
to a structure containing arguments, previously set by
OSSL_CMP_CTX_set_transfer_cb_arg() or NULL if unset.

OSSL_CMP_CTX_set1_srvCert() pins the server certificate to be directly trusted
(even if it is expired) for verifying response messages.
The cert pointer is not consumed. It may be NULL to clear the entry.

OSSL_CMP_CTX_set1_expected_sender() sets the Distinguished Name (DN) expected to
be given in the sender response for messages protected with MSG_SIG_ALG. This
may be used to enforce that during validation of received messages the given DN
matches the sender field of the PKIMessage header, which in turn is used to
identify the server certificate.
This can be used to ensure that only a particular entity is accepted to act as
CMP server, and attackers are not able to use arbitrary certificates of a
trusted PKI hierarchy to fraudulently pose as server.
This defaults to the subject DN of the certificate set via
OSSL_CMP_CTX_set1_srvCert(), if any.

OSSL_CMP_CTX_set0_trustedStore() sets the X509_STORE type certificate store
containing trusted (root) CA certificates. The certificate store may also hold
CRLs and a certificate verification callback function used for CMP server
authentication. Any already existing store entry is freed. When given a NULL
parameter the entry is cleared.

OSSL_CMP_CTX_get0_trustedStore() returns a pointer to the certificate store
containing trusted root CA certificates, which may be empty if unset.

OSSL_CMP_CTX_set1_untrusted_certs() takes over a list of certificates containing
non-trusted intermediate certs used for path construction in authentication
of the CMP server and potentially others (TLS server, newly enrolled cert).
The reference counts of those certificates handled successfully are increased.

OSSL_CMP_CTX_get0_untrusted_certs(OSSL_CMP_CTX *ctx) returns a pointer to the
list of untrusted certs, which my be empty if unset.

OSSL_CMP_CTX_set1_clCert() sets the client certificate in the given
OSSL_CMP_CTX structure. The client certificate will then be used by the
functions to set the "sender" field for outgoing messages and it will be
included in the extraCerts field.

OSSL_CMP_CTX_set1_pkey() sets the private key corresponding to the client
certificate set with B<OSSL_CMP_CTX_set1_clCert()> in the given CMP context.
Used to create the protection in case of MSG_SIG_ALG.

OSSL_CMP_CTX_set1_referenceValue() sets the given referenceValue in the given
B<ctx> or clears it if the B<ref> argument is NULL.

OSSL_CMP_CTX_set1_secretValue() sets the B<sec> with the length B<len> in the
given B<ctx> or clears it if the B<sec> argument is NULL.

OSSL_CMP_CTX_set1_recipient() sets the recipient name that will be used in the
PKIHeader of a request message, i.e. the X509 name of the (CA) server.
Setting is overruled by subject of srvCert if set.
If neither srvCert nor recipient are set, the recipient of the PKI message is
determined in the following order: issuer, issuer of old cert (oldCert),
issuer of client cert (clCert), else NULL-DN.
When a response is received, its sender must match the recipient of the request.

OSSL_CMP_CTX_push0_geninfo_ITAV() adds B<itav> to the stack in the B<ctx> to be
added to the GeneralInfo field of the CMP PKIMessage header of a request
message sent with this context.  Consumes the pointer to B<itav>.

OSSL_CMP_CTX_set1_extraCertsOut() sets the stack of extraCerts that will be
sent to remote.

OSSL_CMP_CTX_set0_newPkey() can be used to explicitly set the given EVP_PKEY
structure as the private or public key to be certified in the CMP context.
The B<priv> parameter must be 0 if and only if the given key is a public key.

OSSL_CMP_CTX_get0_newPkey() gives the key to use for certificate enrollment
dependent on fields of the CMP context structure:
the newPkey (which may be a private or public key) if present,
else the public key in the p10CSR if present, else the client private key.
If the B<priv> parameter is not 0 and the selected key does not have a
private component then NULL is returned.

OSSL_CMP_CTX_set1_issuer() sets the name of the intended issuer that
will be set in the CertTemplate, i.e., the X509 name of the CA server.

OSSL_CMP_CTX_set1_subjectName() sets the subject DN that will be used in
the CertTemplate structure when requesting a new cert. For Key Update Requests
(KUR), it defaults to the subject DN of the reference certificate,
see B<OSSL_CMP_CTX_set1_oldCert()>. This default is used for Initialization
Requests (IR) and Certification Requests (CR) only if no SANs are set.

If clCert is not set (e.g. in case of IR with MSG_MAC_ALG), the subject DN
is also used as sender of the PKI message.

OSSL_CMP_CTX_push1_subjectAltName() adds the given X509 name to the list of
alternate names on the certificate template request. This cannot be used if
any Subject Alternative Name extension is set via
OSSL_CMP_CTX_set0_reqExtensions().
By default, unless OSSL_CMP_OPT_SUBJECTALTNAME_NODEFAULT has been set,
the Subject Alternative Names are copied from the reference certificate,
see OSSL_CMP_CTX_set1_oldCert().

If set and the subject DN is not set with OSSL_CMP_CTX_set1_subjectName(), then
the certificate template of an IR and CR will not be filled with the default
subject DN from the reference certificate (see OSSL_CMP_CTX_set1_oldCert().
If a subject DN is desired it needs to be set explicitly with
OSSL_CMP_CTX_set1_subjectName().

OSSL_CMP_CTX_set0_reqExtensions() sets the X.509v3 extensions to be used in
IR/CR/KUR.

OSSL_CMP_CTX_reqExtensions_have_SAN() returns 1 if the context contains
a Subject Alternative Name extension, else 0 or -1 on error.

OSSL_CMP_CTX_push0_policy() adds the certificate policy info object
to the X509_EXTENSIONS of the requested certificate template.

OSSL_CMP_CTX_set1_oldCert() sets the old certificate to be updated in
Key Update Requests (KUR) or to be revoked in Revocation Requests (RR).
It must be given for RR, else it defaults to B<clCert>.
The reference certificate determined in this way, if any, is also used for
deriving default subject DN and Subject Alternative Names for IR, CR, and KUR.
Its issuer, if any, is used as default recipient in the CMP message header.

OSSL_CMP_CTX_set1_p10CSR() sets the PKCS#10 CSR to be used in P10CR.

OSSL_CMP_CTX_push0_genm_ITAV() adds B<itav> to the stack in the B<ctx> which
will be the body of a General Message sent with this context.
Consumes the pointer to B<itav>.

OSSL_CMP_CTX_set_certConf_cb() sets the callback used for evaluating the newly
enrolled certificate before the library sends, depending on its result,
a positive or negative certConf message to the server. The callback has type

 typedef int (*OSSL_cmp_certConf_cb_t) (OSSL_CMP_CTX *ctx, X509 *cert,
                                        int fail_info, const char **txt);

and should inspect the certificate it obtains via the B<cert> parameter and may
overrule the pre-decision given in the B<fail_info> and B<*txt> parameters.
If it accepts the certificate it must return 0, indicating success. Else it must
return a bit field reflecting PKIFailureInfo with at least one failure bit and
may set the B<*txt> output parameter to point to a string constant with more
detail.  The transfer callback may make use of a custom defined argument stored
in the B<ctx> by means of OSSL_CMP_CTX_set_certConf_cb_arg(), which may be
retrieved again through OSSL_CMP_CTX_get_certConf_cb_arg().
Typically, the callback will check at least that the certificate can be verified
using a set of trusted certificates.
It also could compare the subject DN and other fields of the newly
enrolled certificate with the certificate template of the request.

OSSL_CMP_CTX_set_certConf_cb_arg() sets an argument, respectively a pointer to a
structure containing arguments, optionally to be used by the certConf callback.
B<arg> is not consumed, and it must therefore explicitly be freed when not
needed any more. B<arg> may be NULL to clear the entry.

OSSL_CMP_CTX_get_certConf_cb_arg() gets the argument, respectively the pointer
to a structure containing arguments, previously set by
OSSL_CMP_CTX_set_certConf_cb_arg(), or NULL if unset.

OSSL_CMP_CTX_get_status() returns the PKIstatus from the last received
CertRepMessage or Revocation Response or error message, or -1 if unset.

OSSL_CMP_CTX_get0_statusString() returns the statusString from the last received
CertRepMessage or Revocation Response or error message, or NULL if unset.

OSSL_CMP_CTX_get_failInfoCode() returns the error code from the failInfo field
of the last received CertRepMessage or Revocation Response or error message.
This is a bit field and the flags for it are specified in the header file
F<< <openssl/cmp.h> >>.
The flags start with OSSL_CMP_CTX_FAILINFO, for example:
OSSL_CMP_CTX_FAILINFO_badAlg. Returns -1 if the failInfoCode field is unset.

OSSL_CMP_CTX_get0_newCert() returns the pointer to the newly obtained
certificate in case it is available, else NULL.

OSSL_CMP_CTX_get1_caPubs() returns a pointer to a duplicate of the stack of
X.509 certificates received in the caPubs field of last received certificate
response message IP/CP/KUP.

OSSL_CMP_CTX_get1_extraCertsIn() returns a pointer to a duplicate of the stack
of X.509 certificates received in the last received non-empty extraCerts field.
Returns an empty stack if no extraCerts have been received in the current
transaction.

OSSL_CMP_CTX_set1_transactionID() sets the given transaction ID in the given
OSSL_CMP_CTX structure.

OSSL_CMP_CTX_set1_senderNonce() stores the last sent sender B<nonce> in
the B<ctx>. This will be used to validate the recipNonce in incoming messages.

=head1 NOTES

CMP is defined in RFC 4210 (and CRMF in RFC 4211).

=head1 RETURN VALUES

OSSL_CMP_CTX_free() and OSSL_CMP_CTX_print_errors() do not return anything.

OSSL_CMP_CTX_new(),
OSSL_CMP_CTX_get_http_cb_arg(),
OSSL_CMP_CTX_get_transfer_cb_arg(),
OSSL_CMP_CTX_get0_trustedStore(),
OSSL_CMP_CTX_get0_untrusted_certs(),
OSSL_CMP_CTX_get0_newPkey(),
OSSL_CMP_CTX_get_certConf_cb_arg(),
OSSL_CMP_CTX_get0_statusString(),
OSSL_CMP_CTX_get0_newCert(),
OSSL_CMP_CTX_get1_caPubs(), and
OSSL_CMP_CTX_get1_extraCertsIn()
return the intended pointer value as described above or NULL on error.

OSSL_CMP_CTX_get_option(),
OSSL_CMP_CTX_reqExtensions_have_SAN(),
OSSL_CMP_CTX_get_status(), and
OSSL_CMP_CTX_get_failInfoCode()
return the intended value as described above or -1 on error.

All other functions return 1 on success, 0 on error.

=head1 EXAMPLES

The following code does an Initialization Request:

        cmp_ctx = OSSL_CMP_CTX_new();
        OSSL_CMP_CTX_set1_serverName(cmp_ctx, opt_serverName);
        OSSL_CMP_CTX_set1_referenceValue(cmp_ctx, ref, ref_len);
        OSSL_CMP_CTX_set1_secretValue(cmp_ctx, sec, sec_len);
        OSSL_CMP_CTX_set0_newPkey(cmp_ctx, new_pkey, 1);
        OSSL_CMP_CTX_set1_caCert(cmp_ctx, ca_cert);

        initialClCert = OSSL_CMP_exec_IR_ses(cmp_ctx);

The following code does an Initialization Request using an
external identity certificate (RFC 4210, Appendix E.7):

        cmp_ctx = OSSL_CMP_CTX_new();
        OSSL_CMP_CTX_set1_serverName(cmp_ctx, sname);
        OSSL_CMP_CTX_set1_clCert(cmp_ctx, cl_cert);
        OSSL_CMP_CTX_set1_pkey(cmp_ctx, pkey);
        OSSL_CMP_CTX_set0_newPkey(cmp_ctx, new_pkey, 1);
        OSSL_CMP_CTX_set1_caCert(cmp_ctx, ca_cert);

        initialClCert = OSSL_CMP_exec_IR_ses(cmp_ctx);

Here externalCert is an X509 certificate granted to the EE by another CA
which is trusted by the current CA the code will connect to.


The following code does a Key Update Request:

        cmp_ctx = OSSL_CMP_CTX_new();
        OSSL_CMP_CTX_set1_serverName(cmp_ctx, sname);
        OSSL_CMP_CTX_set1_pkey(cmp_ctx, pkey);
        OSSL_CMP_CTX_set0_newPkey(cmp_ctx, new_pkey, 1);
        OSSL_CMP_CTX_set1_clCert(cmp_ctx, cl_cert);
        OSSL_CMP_CTX_set1_caCert(cmp_ctx, ca_cert);

        updatedClCert = OSSL_CMP_exec_KUR_ses(cmp_ctx);

The following code (which omits error handling) sends a General Message
including, as an example, the id-it-signKeyPairTypes OID and prints info on
the General Response contents.

    cmp_ctx = OSSL_CMP_CTX_new();
    OSSL_CMP_CTX_set1_serverName(cmp_ctx, sname);
    OSSL_CMP_CTX_set1_referenceValue(cmp_ctx, ref, ref_len);
    OSSL_CMP_CTX_set1_secretValue(cmp_ctx, sec, sec_len);

    ASN1_OBJECT *type = OBJ_txt2obj("1.3.6.1.5.5.7.4.2", 1);
    OSSL_CMP_ITAV *itav = OSSL_CMP_ITAV_new(type, NULL);
    OSSL_CMP_CTX_push0_genm_ITAV(cmp_ctx, itav);

    STACK_OF(OSSL_CMP_ITAV) *itavs;
    itavs = OSSL_CMP_exec_GENM_ses(cmp_ctx);
    print_itavs(itavs);
    sk_OSSL_CMP_ITAV_pop_free(itavs, OSSL_CMP_ITAV_free);

=head1 SEE ALSO

L<OSSL_CMP_exec_IR_ses(3)>, L<OSSL_CMP_exec_KUR_ses(3)>,
L<OSSL_CMP_exec_GENM_ses(3)>

=head1 HISTORY

The OpenSSL CMP support was added in OpenSSL 3.0.

=head1 COPYRIGHT

Copyright 2007-2019 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
L<https://www.openssl.org/source/license.html>.

=cut