.\" $OpenBSD: X509V3_EXT_print.3,v 1.2 2021/07/12 14:54:00 schwarze Exp $ .\" .\" Copyright (c) 2021 Ingo Schwarze .\" .\" Permission to use, copy, modify, and distribute this software for any .\" purpose with or without fee is hereby granted, provided that the above .\" copyright notice and this permission notice appear in all copies. .\" .\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES .\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF .\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR .\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES .\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN .\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF .\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. .\" .Dd $Mdocdate: July 12 2021 $ .Dt X509V3_EXT_PRINT 3 .Os .Sh NAME .Nm X509V3_EXT_print .Nd pretty-print an X.509 extension .Sh SYNOPSIS .In openssl/x509v3.h .Ft int .Fo X509V3_EXT_print .Fa "BIO *bio" .Fa "X509_EXTENSION *ext" .Fa "unsigned long flags" .Fa "int indent" .Fc .Sh DESCRIPTION .Fn X509V3_EXT_print decodes .Fa ext and prints the data contained in it to .Fa bio in a human-readable format with a left margin of .Fa indent space characters. The details of both the decoding and the printing depend on the type of .Fa ext . .Pp For most extension types, the decoding is done in the same way as it would be done by the appropriate public API function, for example: .Pp .Bl -tag -width NID_authority_key_identifier -compact .It Sy extension type .Sy decoding function .It Dv NID_subject_key_identifier .Xr d2i_ASN1_OCTET_STRING 3 .It Dv NID_key_usage .Xr d2i_ASN1_BIT_STRING 3 .It Dv NID_crl_number .Xr d2i_ASN1_INTEGER 3 .It Dv NID_crl_reason .Xr d2i_ASN1_ENUMERATED 3 .It Dv NID_invalidity_date .Xr d2i_ASN1_GENERALIZEDTIME 3 .It Dv NID_subject_alt_name .Xr d2i_GENERAL_NAMES 3 .It Dv NID_hold_instruction_code .Xr d2i_ASN1_OBJECT 3 .It Dv NID_id_pkix_OCSP_noCheck .Xr d2i_ASN1_NULL 3 .It Dv NID_authority_key_identifier .Xr d2i_AUTHORITY_KEYID 3 .It Dv NID_certificate_policies .Xr d2i_CERTIFICATEPOLICIES 3 .It Dv NID_id_pkix_OCSP_CrlID .Xr d2i_OCSP_CRLID 3 .It Dv NID_id_pkix_OCSP_Nonce non-public function built into the library .El .Pp For some types, the printing is performed by a dedicated non-public function built into the library. For some other types, the printing function is a public API function, but none of these printing functions are documented yet. .Pp If .Fa ext is of an unknown extension type or if decoding fails while using the decoding function for the relevant type, the action taken depends on the .Fa flags argument: .Bl -bullet .It If the bit .Dv X509V3_EXT_PARSE_UNKNOWN is set, .Xr ASN1_parse_dump 3 is called on the BER-encoded data of the extension, passing \-1 for the .Fa dump argument. Thus, some information about the encoding of the extension gets printed and some about its decoded content, falling back to .Xr BIO_dump_indent 3 for the decoded content unless a dedicated printing method is known for the respective data type(s). Note that even if an extension type is unknown, the data type used by the unknown extension, or, if that data type is constructed, of the values contained in it, may still be known, which may allow printing the content of even an unknown extension in a structured or partially structured form. .It If the bit .Dv X509V3_EXT_DUMP_UNKNOWN is set, .Xr BIO_dump_indent 3 is called on the BER-encoded data of the extension without decoding it first, which is usually less readable than the above but poses a smaller risk of omitting or misrepresenting parts of the information. .It If the bit .Dv X509V3_EXT_ERROR_UNKNOWN is set, only the fixed string .Qq "" is printed for an unknown type or only the fixed string .Qq "" if the parsing functions fails, but printing is considered as successful anyway. .It If more than one of these three bits is set, or if a bit in .Dv X509V3_EXT_UNKNOWN_MASK is set that is not listed above, nothing is printed, but printing is considered as successful anyway. .It If none of the bits in .Dv X509V3_EXT_UNKNOWN_MASK are set, nothing is printed and printing is considered as failed. .El .Sh RETURN VALUES .Fn X509V3_EXT_print returns 0 if failure was both detected and considered relevant. Otherwise, 1 is returned, and in general the user cannot tell whether failure simply went undetected, whether the function detected failure but regarded it as irrelevant, or whether printing did indeed succeed. .Sh SEE ALSO .Xr BIO_new 3 , .Xr X509_EXTENSION_new 3 , .Xr X509_get0_extensions 3 , .Xr X509_get_ext 3 , .Xr X509V3_extensions_print 3 .Sh HISTORY .Fn X509V3_EXT_print first appeared in OpenSSL 0.9.2 and has been available since .Ox 2.6 . .Sh BUGS .Fn X509V3_EXT_print lacks error handling throughout. When a write operation fails, it will usually ignore the fact that information was omitted from the output and report success to the caller anyway.