This commit was manufactured by cvs2svn to create branch

=pod

=head1 NAME

SSL_CTX_get_ex_new_index, SSL_CTX_set_ex_data, SSL_CTX_get_ex_data - internal application specific data functions

=head1 SYNOPSIS

 #include <openssl/ssl.h>

 int SSL_CTX_get_ex_new_index(long argl, void *argp,

                CRYPTO_EX_new *new_func,

                CRYPTO_EX_dup *dup_func,

                CRYPTO_EX_free *free_func);

 int SSL_CTX_set_ex_data(SSL_CTX *ctx, int idx, void *arg);

 void *SSL_CTX_get_ex_data(SSL_CTX *ctx, int idx);

 typedef int new_func(void *parent, void *ptr, CRYPTO_EX_DATA *ad,

                int idx, long argl, void *argp);

 typedef void free_func(void *parent, void *ptr, CRYPTO_EX_DATA *ad,

                int idx, long argl, void *argp);

 typedef int dup_func(CRYPTO_EX_DATA *to, CRYPTO_EX_DATA *from, void *from_d,

                int idx, long argl, void *argp);

=head1 DESCRIPTION

Several OpenSSL structures can have application specific data attached to them.

These functions are used internally by OpenSSL to manipulate application

specific data attached to a specific structure.

SSL_CTX_get_ex_new_index() is used to register a new index for application

specific data.

SSL_CTX_set_ex_data() is used to store application data at B<arg> for B<idx>

into the B<ctx> object.

SSL_CTX_get_ex_data() is used to retrieve the information for B<idx> from

B<ctx>.

A detailed description for the B<*_get_ex_new_index()> functionality

can be found in L<RSA_get_ex_new_index.pod(3)|RSA_get_ex_new_index.pod(3)>.

The B<*_get_ex_data()> and B<*_set_ex_data()> functionality is described in

L<CRYPTO_set_ex_data(3)|CRYPTO_set_ex_data(3)>.

=head1 SEE ALSO

L<ssl(3)|ssl(3)>,

L<RSA_get_ex_new_index(3)|RSA_get_ex_new_index(3)>,

L<CRYPTO_set_ex_data(3)|CRYPTO_set_ex_data(3)>

=cut

=pod

=head1 NAME

SSL_CTX_set_verify, SSL_set_verify, SSL_CTX_set_verify_depth, SSL_set_verify_depth - set peer certificate verification parameters

=head1 SYNOPSIS

 #include <openssl/ssl.h>

 void SSL_CTX_set_verify(SSL_CTX *ctx, int mode,

                         int (*verify_callback)(int, X509_STORE_CTX *));

 void SSL_set_verify(SSL *s, int mode,

                     int (*verify_callback)(int, X509_STORE_CTX *));

 void SSL_CTX_set_verify_depth(SSL_CTX *ctx,int depth);

 void SSL_set_verify_depth(SSL *s, int depth);

 int verify_callback(int preverify_ok, X509_STORE_CTX *x509_ctx);

=head1 DESCRIPTION

SSL_CTX_set_verify() sets the verification flags for B<ctx> to be B<mode> and

specifies the B<verify_callback> function to be used. If no callback function

shall be specified, the NULL pointer can be used for B<verify_callback>.

SSL_set_verify() sets the verification flags for B<ssl> to be B<mode> and

specifies the B<verify_callback> function to be used. If no callback function

shall be specified, the NULL pointer can be used for B<verify_callback>. In

this case last B<verify_callback> set specifically for this B<ssl> remains. If

no special B<callback> was set before, the default callback for the underlying

B<ctx> is used, that was valid at the the time B<ssl> was created with

L<SSL_new(3)|SSL_new(3)>.

SSL_CTX_set_verify_depth() sets the maximum B<depth> for the certificate chain

verification that shall be allowed for B<ctx>. (See the BUGS section.)

SSL_set_verify_depth() sets the maximum B<depth> for the certificate chain

verification that shall be allowed for B<ssl>. (See the BUGS section.)

=head1 NOTES

The verification of certificates can be controlled by a set of logically

or'ed B<mode> flags:

=over 4

=item SSL_VERIFY_NONE

B<Server mode:> the server will not send a client certificate request to the

client, so the client will not send a certificate.

B<Client mode:> if not using an anonymous cipher (by default disabled), the

server will send a certificate which will be checked. The result of the

certificate verification process can be checked after the TLS/SSL handshake

using the L<SSL_get_verify_result(3)|SSL_get_verify_result(3)> function.

The handshake will be continued regardless of the verification result.

=item SSL_VERIFY_PEER

B<Server mode:> the server sends a client certificate request to the client.

The certificate returned (if any) is checked. If the verification process

fails as indicated by B<verify_callback>, the TLS/SSL handshake is

immediately terminated with an alert message containing the reason for

the verification failure.

The behaviour can be controlled by the additional

SSL_VERIFY_FAIL_IF_NO_PEER_CERT and SSL_VERIFY_CLIENT_ONCE flags.

B<Client mode:> the server certificate is verified. If the verification process

fails as indicated by B<verify_callback>, the TLS/SSL handshake is

immediately terminated with an alert message containing the reason for

the verification failure. If no server certificate is sent, because an

anonymous cipher is used, SSL_VERIFY_PEER is ignored.

=item SSL_VERIFY_FAIL_IF_NO_PEER_CERT

B<Server mode:> if the client did not return a certificate, the TLS/SSL

handshake is immediately terminated with a "handshake failure" alert.

This flag must be used together with SSL_VERIFY_PEER.

B<Client mode:> ignored

=item SSL_VERIFY_CLIENT_ONCE

B<Server mode:> only request a client certificate on the initial TLS/SSL

handshake. Do not ask for a client certificate again in case of a

renegotiation. This flag must be used together with SSL_VERIFY_PEER.

B<Client mode:> ignored

=back

Exactly one of the B<mode> flags SSL_VERIFY_NONE and SSL_VERIFY_PEER must be

set at any time.

SSL_CTX_set_verify_depth() and SSL_set_verify_depth() set the limit up

to which depth certificates in a chain are used during the verification

procedure. If the certificate chain is longer than allowed, the certificates

above the limit are ignored. Error messages are generated as if these

certificates would not be present, most likely a

X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY will be issued.

The depth count is "level 0:peer certificate", "level 1: CA certificate",

"level 2: higher level CA certificate", and so on. Setting the maximum

depth to 2 allows the levels 0, 1, and 2. The default depth limit is 9,

allowing for the peer certificate and additional 9 CA certificates.

The B<verify_callback> function is used to control the behaviour when the

SSL_VERIFY_PEER flag is set. It must be supplied by the application and

receives two arguments: B<preverify_ok> indicates, whether the verification of

the certificate in question was passed (preverify_ok=1) or not

(preverify_ok=0). B<x509_ctx> is a pointer to the complete context used

for the certificate chain verification.

The certificate chain is checked starting with the deepest nesting level

(the root CA certificate) and worked upward to the peer's certificate.

At each level signatures and issuer attributes are checked. Whenever

a verification error is found, the error number is stored in B<x509_ctx>

and B<verify_callback> is called with B<preverify_ok>=0. By applying

X509_CTX_store_* functions B<verify_callback> can locate the certificate

in question and perform additional steps (see EXAMPLES). If no error is

found for a certificate, B<verify_callback> is called with B<preverify_ok>=1

before advancing to the next level.

The return value of B<verify_callback> controls the strategy of the further

verification process. If B<verify_callback> returns 0, the verification

process is immediately stopped with "verification failed" state. If

SSL_VERIFY_PEER is set, a verification failure alert is sent to the peer and

the TLS/SSL handshake is terminated. If B<verify_callback> returns 1,

the verification process is continued. If B<verify_callback> always returns

1, the TLS/SSL handshake will never be terminated because of this application

experiencing a verification failure. The calling process can however

retrieve the error code of the last verification error using

L<SSL_get_verify_result(3)|SSL_get_verify_result(3)> or by maintaining its

own error storage managed by B<verify_callback>.

If no B<verify_callback> is specified, the default callback will be used.

Its return value is identical to B<preverify_ok>, so that any verification

failure will lead to a termination of the TLS/SSL handshake with an

alert message, if SSL_VERIFY_PEER is set.

=head1 BUGS

In client mode, it is not checked whether the SSL_VERIFY_PEER flag

is set, but whether SSL_VERIFY_NONE is not set. This can lead to

unexpected behaviour, if the SSL_VERIFY_PEER and SSL_VERIFY_NONE are not

used as required (exactly one must be set at any time).

The certificate verification depth set with SSL[_CTX]_verify_depth()

stops the verification at a certain depth. The error message produced

will be that of an incomplete certificate chain and not

X509_V_ERR_CERT_CHAIN_TOO_LONG as may be expected.

=head1 RETURN VALUES

The SSL*_set_verify*() functions do not provide diagnostic information.

=head1 EXAMPLES

The following code sequence realizes an example B<verify_callback> function

that will always continue the TLS/SSL handshake regardless of verification

failure, if wished. The callback realizes a verification depth limit with

more informational output.

All verification errors are printed, informations about the certificate chain

are printed on request.

The example is realized for a server that does allow but not require client

certificates.

The example makes use of the ex_data technique to store application data

into/retrieve application data from the SSL structure

(see L<SSL_get_ex_new_index(3)|SSL_get_ex_new_index(3)>,

L<SSL_get_ex_data_X509_STORE_CTX_idx(3)|SSL_get_ex_data_X509_STORE_CTX_idx(3)>).

 ...

 typedef struct {

   int verbose_mode;

   int verify_depth;

   int always_continue;

 } mydata_t;

 int mydata_index;

 ...

 static int verify_callback(int preverify_ok, X509_STORE_CTX *ctx)

 {

    char    buf[256];

    X509   *err_cert;

    int     err, depth;

    SSL    *ssl;

    mydata_t *mydata;

    err_cert = X509_STORE_CTX_get_current_cert(ctx);

    err = X509_STORE_CTX_get_error(ctx);

    depth = X509_STORE_CTX_get_error_depth(ctx);

    /*

     * Retrieve the pointer to the SSL of the connection currently treated

     * and the application specific data stored into the SSL object.

     */

    ssl = X509_STORE_CTX_get_ex_data(ctx, SSL_get_ex_data_X509_STORE_CTX_idx());

    mydata = SSL_get_ex_data(ssl, mydata_index);

    X509_NAME_oneline(X509_get_subject_name(err_cert), buf, 256);

    /*

     * Catch a too long certificate chain. The depth limit set using

     * SSL_CTX_set_verify_depth() is by purpose set to "limit+1" so

     * that whenever the "depth>verify_depth" condition is met, we

     * have violated the limit and want to log this error condition.

     * We must do it here, because the CHAIN_TOO_LONG error would not

     * be found explicitly; only errors introduced by cutting off the

     * additional certificates would be logged.

     */

    if (depth > mydata->verify_depth) {

        preverify_ok = 0;

        err = X509_V_ERR_CERT_CHAIN_TOO_LONG;

        X509_STORE_CTX_set_error(ctx, err);

    } 

    if (!preverify_ok) {

        printf("verify error:num=%d:%s:depth=%d:%s\n", err,

                 X509_verify_cert_error_string(err), depth, buf);

    }

    else if (mydata->verbose_mode)

    {

        printf("depth=%d:%s\n", depth, buf);

    }

    /*

     * At this point, err contains the last verification error. We can use

     * it for something special

     */

    if (!preverify_ok && (err == X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT)

    {

      X509_NAME_oneline(X509_get_issuer_name(ctx->current_cert), buf, 256);

      printf("issuer= %s\n", buf);

    }

    if (mydata->always_continue)

      return 1;

    else

      return preverify_ok;

 }

 ...

 mydata_t mydata;

 ...

 mydata_index = SSL_get_ex_new_index(0, "mydata index", NULL, NULL, NULL);

 ...

 SSL_CTX_set_verify(ctx, SSL_VERIFY_PEER|SSL_VERIFY_CLIENT_ONCE,

                    verify_callback);

 /*

  * Let the verify_callback catch the verify_depth error so that we get

  * an appropriate error in the logfile.

  */

 SSL_CTX_set_verify_depth(verify_depth + 1);

 /*

  * Set up the SSL specific data into "mydata" and store it into th SSL

  * structure.

  */

 mydata.verify_depth = verify_depth; ...

 SSL_set_ex_data(ssl, mydata_index, &mydata);

 ...

 SSL_accept(ssl);	/* check of success left out for clarity */

 if (peer = SSL_get_peer_certificate(ssl))

 {

   if (SSL_get_verify_result(ssl) == X509_V_OK)

   {

     /* The client sent a certificate which verified OK */

   }

 }

=head1 SEE ALSO

L<ssl(3)|ssl(3)>, L<SSL_new(3)|SSL_new(3)>,

L<SSL_CTX_get_verify_mode(3)|SSL_CTX_get_verify_mode(3)>,

L<SSL_get_verify_result(3)|SSL_get_verify_result(3)>,

L<SSL_CTX_load_verify_locations(3)|SSL_CTX_load_verify_locations(3)>,

L<SSL_get_peer_certificate(3)|SSL_get_peer_certificate(3)>,

L<SSL_get_ex_data_X509_STORE_CTX_idx(3)|SSL_get_ex_data_X509_STORE_CTX_idx(3)>,

L<SSL_get_ex_new_index(3)|SSL_get_ex_new_index(3)>

=cut

=pod

=head1 NAME

SSL_CTX_use_certificate, SSL_CTX_use_certificate_ASN1, SSL_CTX_use_certificate_file, SSL_use_certificate, SSL_use_certificate_ASN1, SSL_use_certificate_file, SSL_CTX_use_certificate_chain_file, SSL_CTX_use_PrivateKey, SSL_CTX_use_PrivateKey_ASN1, SSL_CTX_use_PrivateKey_file, SSL_CTX_use_RSAPrivateKey, SSL_CTX_use_RSAPrivateKey_ASN1, SSL_CTX_use_RSAPrivateKey_file, SSL_use_PrivateKey_file, SSL_use_PrivateKey_ASN1, SSL_use_PrivateKey, SSL_use_RSAPrivateKey, SSL_use_RSAPrivateKey_ASN1, SSL_use_RSAPrivateKey_file, SSL_CTX_check_private_key, SSL_check_private_key - load certificate and key data

=head1 SYNOPSIS

 #include <openssl/ssl.h>

 int SSL_CTX_use_certificate(SSL_CTX *ctx, X509 *x);

 int SSL_CTX_use_certificate_ASN1(SSL_CTX *ctx, int len, unsigned char *d);

 int SSL_CTX_use_certificate_file(SSL_CTX *ctx, const char *file, int type);

 int SSL_use_certificate(SSL *ssl, X509 *x);

 int SSL_use_certificate_ASN1(SSL *ssl, unsigned char *d, int len);

 int SSL_use_certificate_file(SSL *ssl, const char *file, int type);

 int SSL_CTX_use_certificate_chain_file(SSL_CTX *ctx, const char *file);

 int SSL_CTX_use_PrivateKey(SSL_CTX *ctx, EVP_PKEY *pkey);

 int SSL_CTX_use_PrivateKey_ASN1(int pk, SSL_CTX *ctx, unsigned char *d,

				 long len);

 int SSL_CTX_use_PrivateKey_file(SSL_CTX *ctx, const char *file, int type);

 int SSL_CTX_use_RSAPrivateKey(SSL_CTX *ctx, RSA *rsa);

 int SSL_CTX_use_RSAPrivateKey_ASN1(SSL_CTX *ctx, unsigned char *d, long len);

 int SSL_CTX_use_RSAPrivateKey_file(SSL_CTX *ctx, const char *file, int type);

 int SSL_use_PrivateKey(SSL *ssl, EVP_PKEY *pkey);

 int SSL_use_PrivateKey_ASN1(int pk,SSL *ssl, unsigned char *d, long len);

 int SSL_use_PrivateKey_file(SSL *ssl, const char *file, int type);

 int SSL_use_RSAPrivateKey(SSL *ssl, RSA *rsa);

 int SSL_use_RSAPrivateKey_ASN1(SSL *ssl, unsigned char *d, long len);

 int SSL_use_RSAPrivateKey_file(SSL *ssl, const char *file, int type);

 int SSL_CTX_check_private_key(SSL_CTX *ctx);

 int SSL_check_private_key(SSL *ssl);

=head1 DESCRIPTION

These functions load the certificates and private keys into the SSL_CTX

or SSL object, respectively.

The SSL_CTX_* class of functions loads the certificates and keys into the

SSL_CTX object B<ctx>. The information is passed to SSL objects B<ssl>

created from B<ctx> with L<SSL_new(3)|SSL_new(3)> by copying, so that

changes applied to B<ctx> do not propagate to already existing SSL objects.

The SSL_* class of functions only loads certificates and keys into a

specific SSL object. The specific information is kept, when

L<SSL_clear(3)|SSL_clear(3)> is called for this SSL object.

SSL_CTX_use_certificate() loads the certificate B<x> into B<ctx>,

SSL_use_certificate() loads B<x> into B<ssl>.

SSL_CTX_use_certificate_ASN1() loads the ASN1 encoded certificate from

the memory location B<d> (with length B<len>) into B<ctx>,

SSL_use_certificate_ASN1() loads the ASN1 encoded certificate into B<ssl>.

SSL_CTX_use_certificate_file() loads the first certificate stored in B<file>

into B<ctx>. The formatting B<type> of the certificate must be specified

from the known types SSL_FILETYPE_PEM, SSL_FILETYPE_ASN1.

SSL_use_certificate_file() loads the certificate from B<file> into B<ssl>.

SSL_CTX_use_certificate_chain_file() loads a certificate chain from 

B<file> into B<ctx>. The certificates must be in PEM format and must

be sorted starting with the certificate to the highest level (root CA).

There is no corresponding function working on a single SSL object.

SSL_CTX_use_PrivateKey() adds B<pkey> as private key to B<ctx>.

SSL_CTX_use_RSAPrivateKey() adds the private key B<rsa> of type RSA

to B<ctx>. SSL_use_PrivateKey() adds B<pkey> as private key to B<ssl>;

SSL_use_RSAPrivateKey() adds B<rsa> as private key of type RSA to B<ssl>.

SSL_CTX_use_PrivateKey_ASN1() adds the private key of type B<pk>

stored at memory location B<d> (length B<len>) to B<ctx>.

SSL_CTX_use_RSAPrivateKey_ASN1() adds the private key of type RSA

stored at memory location B<d> (length B<len>) to B<ctx>.

SSL_use_PrivateKey_ASN1() and SSL_use_RSAPrivateKey_ASN1() add the private

key to B<ssl>.

SSL_CTX_use_PrivateKey_file() adds the first private key found in

B<file> to B<ctx>. The formatting B<type> of the certificate must be specified

from the known types SSL_FILETYPE_PEM, SSL_FILETYPE_ASN1.

SSL_CTX_use_RSAPrivateKey_file() adds the first private RSA key found in

B<file> to B<ctx>. SSL_use_PrivateKey_file() adds the first private key found

in B<file> to B<ssl>; SSL_use_RSAPrivateKey_file() adds the first private

RSA key found to B<ssl>.

SSL_CTX_check_private_key() checks the consistency of a private key with

the corresponding certificate loaded into B<ctx>. If more than one

key/certificate pair (RSA/DSA) is installed, the last item installed will

be checked. If e.g. the last item was a RSA certificate or key, the RSA

key/certificate pair will be checked. SSL_check_private_key() performs

the same check for B<ssl>. If no key/certificate was explicitly added for

this B<ssl>, the last item added into B<ctx> will be checked.

=head1 NOTES

The internal certificate store of OpenSSL can hold two private key/certificate

pairs at a time: one key/certificate of type RSA and one key/certificate

of type DSA. The certificate used depends on the cipher select, see

also L<SSL_CTX_set_cipher_list(3)|SSL_CTX_set_cipher_list(3)>.

When reading certificates and private keys from file, files of type

SSL_FILETYPE_ASN1 (also known as B<DER>, binary encoding) can only contain

one certificate or private key, consequently 

SSL_CTX_use_certificate_chain_file() is only applicable to PEM formatting.

Files of type SSL_FILETYPE_PEM can contain more than one item.

SSL_CTX_use_certificate_chain_file() adds the first certificate found

in the file to the certificate store. The other certificates are added

to the store of chain certificates using

L<SSL_CTX_add_extra_chain_cert(3)|SSL_CTX_add_extra_chain_cert(3)>.

There exists only one extra chain store, so that the same chain is appended

to both types of certificates, RSA and DSA!

If additional certificates are needed to complete the chain during the

TLS negotiation, CA certificates are additionally looked up in the

locations of trusted CA certificates, see

L<SSL_CTX_load_verify_locations(3)|SSL_CTX_load_verify_locations(3)>.

The private keys loaded from file can be encrypted. In order to successfully

load encrypted keys, a function returning the passphrase must have been

supplied, see

L<SSL_CTX_set_default_passwd_cb(3)|SSL_CTX_set_default_passwd_cb(3)>.

(Certificate files might be encrypted as well from the technical point

of view, it however does not make sense as the data in the certificate

is considered public anyway.)

=head1 RETURN VALUES

On success, the functions return 1.

Otherwise check out the error stack to find out the reason.

=head1 SEE ALSO

L<ssl(3)|ssl(3)>, L<SSL_new(3)|SSL_new(3)>, L<SSL_clear(3)|SSL_clear(3)>,

L<SSL_CTX_load_verify_locations(3)|SSL_CTX_load_verify_locations(3)>,

L<SSL_CTX_set_default_passwd_cb(3)|SSL_CTX_set_default_passwd_cb(3)>,

L<SSL_CTX_set_cipher_list(3)|SSL_CTX_set_cipher_list(3)>,

L<SSL_CTX_add_extra_chain_cert(3)|SSL_CTX_add_extra_chain_cert(3)>

=cut

=pod

=head1 NAME

SSL_SESSION_get_ex_new_index, SSL_SESSION_set_ex_data, SSL_SESSION_get_ex_data - internal application specific data functions

=head1 SYNOPSIS

 #include <openssl/ssl.h>

 int SSL_SESSION_get_ex_new_index(long argl, void *argp,

                CRYPTO_EX_new *new_func,

                CRYPTO_EX_dup *dup_func,

                CRYPTO_EX_free *free_func);

 int SSL_SESSION_set_ex_data(SSL_SESSION *session, int idx, void *arg);

 void *SSL_SESSION_get_ex_data(SSL_SESSION *session, int idx);

 typedef int new_func(void *parent, void *ptr, CRYPTO_EX_DATA *ad,

                int idx, long argl, void *argp);

 typedef void free_func(void *parent, void *ptr, CRYPTO_EX_DATA *ad,

                int idx, long argl, void *argp);

 typedef int dup_func(CRYPTO_EX_DATA *to, CRYPTO_EX_DATA *from, void *from_d,

                int idx, long argl, void *argp);

=head1 DESCRIPTION

Several OpenSSL structures can have application specific data attached to them.

These functions are used internally by OpenSSL to manipulate application

specific data attached to a specific structure.

SSL_SESSION_get_ex_new_index() is used to register a new index for application

specific data.

SSL_SESSION_set_ex_data() is used to store application data at B<arg> for B<idx>

into the B<session> object.

SSL_SESSION_get_ex_data() is used to retrieve the information for B<idx> from

B<session>.

A detailed description for the B<*_get_ex_new_index()> functionality

can be found in L<RSA_get_ex_new_index.pod(3)|RSA_get_ex_new_index.pod(3)>.

The B<*_get_ex_data()> and B<*_set_ex_data()> functionality is described in

L<CRYPTO_set_ex_data(3)|CRYPTO_set_ex_data(3)>.

=head1 WARNINGS

The application data is only maintained for sessions held in memory. The

application data is not included when dumping the session with

i2d_SSL_SESSION() (and all functions indirectly calling the dump functions

like PEM_write_SSL_SESSION() and PEM_write_bio_SSL_SESSION()) and can

therefore not be restored.

=head1 SEE ALSO

L<ssl(3)|ssl(3)>,

L<RSA_get_ex_new_index(3)|RSA_get_ex_new_index(3)>,

L<CRYPTO_set_ex_data(3)|CRYPTO_set_ex_data(3)>

=cut

=pod

=head1 NAME

SSL_get_ex_data_X509_STORE_CTX_idx - get ex_data index to access SSL structure

from X509_STORE_CTX

=head1 SYNOPSIS

 #include <openssl/ssl.h>

 int SSL_get_ex_data_X509_STORE_CTX_idx(void);

=head1 DESCRIPTION

SSL_get_ex_data_X509_STORE_CTX_idx() returns the index number under which

the pointer to the SSL object is stored into the X509_STORE_CTX object.

=head1 NOTES

Whenever a X509_STORE_CTX object is created for the verification of the

peers certificate during a handshake, a pointer to the SSL object is

stored into the X509_STORE_CTX object to identify the connection affected.

To retrieve this pointer the X509_STORE_CTX_get_ex_data() function can

be used with the correct index. This index is globally the same for all

X509_STORE_CTX objects and can be retrieved using

SSL_get_ex_data_X509_STORE_CTX_idx(). The index value is set when

SSL_get_ex_data_X509_STORE_CTX_idx() is first called either by the application

program directly or indirectly during other SSL setup functions or during

the handshake.

The value depends on other index values defined for X509_STORE_CTX objects

before the SSL index is created.

=head1 RETURN VALUES

=over 4

=item E<gt>=0

The index value to access the pointer.

=item E<lt>0

An error occurred, check the error stack for a detailed error message.

=back

=head1 EXAMPLES

The index returned from SSL_get_ex_data_X509_STORE_CTX_idx() allows to

access the SSL object for the connection to be accessed during the

verify_callback() when checking the peers certificate. Please check

the example in L<SSL_CTX_set_verify(3)|SSL_CTX_set_verify(3)>,

=head1 SEE ALSO

L<ssl(3)|ssl(3)>, L<SSL_CTX_set_verify(3)|SSL_CTX_set_verify(3)>,

L<CRYPTO_set_ex_data(3)|CRYPTO_set_ex_data(3)>

=cut