More X509 verification docs.

=pod

=head1 NAME

X509_STORE_CTX_get_error, X509_STORE_CTX_set_error, X509_STORE_CTX_get_error_depth, X509_STORE_CTX_get_current_cert, X509_STORE_CTX_get1_chain - get or set certificate verification status information

=head1 SYNOPSIS

 #include <openssl/x509_vfy.h>

 int	X509_STORE_CTX_get_error(X509_STORE_CTX *ctx);

 void	X509_STORE_CTX_set_error(X509_STORE_CTX *ctx,int s);

 int	X509_STORE_CTX_get_error_depth(X509_STORE_CTX *ctx);

 X509 *	X509_STORE_CTX_get_current_cert(X509_STORE_CTX *ctx);

 STACK_OF(X509) *X509_STORE_CTX_get1_chain(X509_STORE_CTX *ctx);

=head1 DESCRIPTION

These functions are typically called after X509_verify_cert() has indicated

an error or in a verification callback to determine the nature of an error.

X509_STORE_CTX_get_error() returns the error code of B<ctx>, see

the B<ERROR CODES> section for a full description of all error codes.

X509_STORE_CTX_set_error() sets the error code of B<ctx> to B<s>. For example

it might be used in a verification callback to set an error based on additional

checks.

X509_STORE_CTX_get_error_depth() returns the B<depth> of the error. This is a

non-negative integer representing where in the certificate chain the error

occurred. If it is zero it occured in the end entity certificate, one if

it is the certificate which signed the end entity certificate and so on.

X509_STORE_CTX_get_current_cert() returns the certificate in B<ctx> which

caused the error or B<NULL> if no certificate is relevant.

X509_STORE_CTX_get1_chain() returns a complete validate chain if a previous

call to X509_verify_cert() is successful. If the call to X509_verify_cert()

is B<not> successful the returned chain may be incomplete or invalid. The

returned chain persists after the B<ctx> structure is freed, when it is

no longer needed it should be free up using:

  sk_X509_pop_free(chain, X509_free);

=head1 RETURN VALUES

X509_STORE_CTX_get_error() returns an B<X509_V_OK> or an error code.

X509_STORE_CTX_get_error_depth() returns a non-negative error depth.

X509_STORE_CTX_get_current_cert() returns the cerificate which caused the

error or B<NULL> if no certificate is relevant to the error.

=head1 ERROR CODES

An exhaustive list of the error codes and messages is shown below, this also

includes the name of the error code as defined in the header file x509_vfy.h

Some of the error codes are defined but never returned: these are described

as "unused".

=over 4

=item B<0 X509_V_OK: ok>

the operation was successful.

=item B<X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT: unable to get issuer certificate>

the issuer certificate could not be found: this occurs if the issuer certificate

of an untrusted certificate cannot be found.

=item B<X509_V_ERR_UNABLE_TO_GET_CRL: unable to get certificate CRL>

the CRL of a certificate could not be found.

=item B<X509_V_ERR_UNABLE_TO_DECRYPT_CERT_SIGNATURE: unable to decrypt certificate's signature>

the certificate signature could not be decrypted. This means that the actual

signature value could not be determined rather than it not matching the

expected value, this is only meaningful for RSA keys.

=item B<X509_V_ERR_UNABLE_TO_DECRYPT_CRL_SIGNATURE: unable to decrypt CRL's signature>

the CRL signature could not be decrypted: this means that the actual signature

value could not be determined rather than it not matching the expected value.

Unused.

=item B<X509_V_ERR_UNABLE_TO_DECODE_ISSUER_PUBLIC_KEY: unable to decode issuer public key>

the public key in the certificate SubjectPublicKeyInfo could not be read.

=item B<X509_V_ERR_CERT_SIGNATURE_FAILURE: certificate signature failure>

the signature of the certificate is invalid.

=item B<X509_V_ERR_CRL_SIGNATURE_FAILURE: CRL signature failure>

the signature of the certificate is invalid.

=item B<X509_V_ERR_CERT_NOT_YET_VALID: certificate is not yet valid>

the certificate is not yet valid: the notBefore date is after the current time.

=item B<X509_V_ERR_CERT_HAS_EXPIRED: certificate has expired>

the certificate has expired: that is the notAfter date is before the current time.

=item B<X509_V_ERR_CRL_NOT_YET_VALID: CRL is not yet valid>

the CRL is not yet valid.

=item B<X509_V_ERR_CRL_HAS_EXPIRED: CRL has expired>

the CRL has expired.

=item B<X509_V_ERR_ERROR_IN_CERT_NOT_BEFORE_FIELD: format error in certificate's notBefore field>

the certificate notBefore field contains an invalid time.

=item B<X509_V_ERR_ERROR_IN_CERT_NOT_AFTER_FIELD: format error in certificate's notAfter field>

the certificate notAfter field contains an invalid time.

=item B<X509_V_ERR_ERROR_IN_CRL_LAST_UPDATE_FIELD: format error in CRL's lastUpdate field>

the CRL lastUpdate field contains an invalid time.

=item B<X509_V_ERR_ERROR_IN_CRL_NEXT_UPDATE_FIELD: format error in CRL's nextUpdate field>

the CRL nextUpdate field contains an invalid time.

=item B<X509_V_ERR_OUT_OF_MEM: out of memory>

an error occurred trying to allocate memory. This should never happen.

=item B<X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT: self signed certificate>

the passed certificate is self signed and the same certificate cannot be found

in the list of trusted certificates.

=item B<X509_V_ERR_SELF_SIGNED_CERT_IN_CHAIN: self signed certificate in certificate chain>

the certificate chain could be built up using the untrusted certificates but

the root could not be found locally.

=item B<X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY: unable to get local issuer certificate>

the issuer certificate of a locally looked up certificate could not be found.

This normally means the list of trusted certificates is not complete.

=item B<X509_V_ERR_UNABLE_TO_VERIFY_LEAF_SIGNATURE: unable to verify the first certificate>

no signatures could be verified because the chain contains only one certificate

and it is not self signed.

=item B<X509_V_ERR_CERT_CHAIN_TOO_LONG: certificate chain too long>

the certificate chain length is greater than the supplied maximum depth. Unused.

=item B<X509_V_ERR_CERT_REVOKED: certificate revoked>

the certificate has been revoked.

=item B<X509_V_ERR_INVALID_CA: invalid CA certificate>

a CA certificate is invalid. Either it is not a CA or its extensions are not

consistent with the supplied purpose.

=item B<X509_V_ERR_PATH_LENGTH_EXCEEDED: path length constraint exceeded>

the basicConstraints pathlength parameter has been exceeded.

=item B<X509_V_ERR_INVALID_PURPOSE: unsupported certificate purpose>

the supplied certificate cannot be used for the specified purpose.

=item B<X509_V_ERR_CERT_UNTRUSTED: certificate not trusted>

the root CA is not marked as trusted for the specified purpose.

=item B<X509_V_ERR_CERT_REJECTED: certificate rejected>

the root CA is marked to reject the specified purpose.

=item B<X509_V_ERR_SUBJECT_ISSUER_MISMATCH: subject issuer mismatch>

the current candidate issuer certificate was rejected because its subject name

did not match the issuer name of the current certificate. This is only set

if issuer check debugging is enabled it is used for status notification and

is B<not> in itself an error.

=item B<X509_V_ERR_AKID_SKID_MISMATCH: authority and subject key identifier mismatch>

the current candidate issuer certificate was rejected because its subject key

identifier was present and did not match the authority key identifier current

certificate. This is only set if issuer check debugging is enabled it is used

for status notification and is B<not> in itself an error.

=item B<X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH: authority and issuer serial number mismatch>

the current candidate issuer certificate was rejected because its issuer name

and serial number was present and did not match the authority key identifier of

the current certificate. This is only set if issuer check debugging is enabled

it is used for status notification and is B<not> in itself an error.

=item B<X509_V_ERR_KEYUSAGE_NO_CERTSIGN:key usage does not include certificate signing>

the current candidate issuer certificate was rejected because its keyUsage

extension does not permit certificate signing. This is only set if issuer check

debugging is enabled it is used for status notification and is B<not> in itself

an error.

=item B<X509_V_ERR_APPLICATION_VERIFICATION: application verification failure>

an application specific error. This will never be returned unless explicitly

set by an application.

=head1 NOTES

The above functions should be used instead of directly referencing the fields

in the B<X509_VERIFY_CTX> structure.

In versions of OpenSSL before 1.0 the current certificate returned by

X509_STORE_CTX_get_current_cert() was never B<NULL>. Applications should

check the return value before printing out any debugging information relating

to the current certificate.

=head1 BUGS

=head1 SEE ALSO

L<X509_verify_cert(3)|X509_verify_cert(3)>

=head1 HISTORY

TBA

=cut

=pod

=head1 NAME

X509_STORE_CTX_get_ex_new_index, X509_STORE_CTX_set_ex_data, X509_STORE_CTX_get_ex_data - add application specific data to X509_STORE_CTX structures

=head1 SYNOPSIS

 #include <openssl/x509_vfy.h>

 int X509_STORE_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 X509_STORE_CTX_set_ex_data(X509_STORE_CTX *d, int idx, void *arg);

 char *X509_STORE_CTX_get_ex_data(X509_STORE_CTX *d, int idx);

=head1 DESCRIPTION

These functions handle application specific data in X509_STORE_CTX structures.

Their usage is identical to that of RSA_get_ex_new_index(), RSA_set_ex_data()

and RSA_get_ex_data() as described in L<RSA_get_ex_new_index(3)>.

=head1 NOTES

This mechanism is used internally by the B<ssl> library to store the B<SSL>

structure associated with a verification operation in an B<X509_STORE_CTX>

structure. 

=head1 SEE ALSO

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

=head1 HISTORY

X509_STORE_CTX_get_ex_new_index(), X509_STORE_CTX_set_ex_data() and

X509_STORE_CTX_get_ex_data() are available since OpenSSL 0.9.5.

=cut

=head1 DESCRIPTION

The X509_verify_cert() function attempts to discover and validate a

certificate chain based on parameters in B<ctx>.

certificate chain based on parameters in B<ctx>. A complete description of

the process is contained in the L<verify(1)|verify(1)> manual page.

=head1 RETURN VALUES