X509_NAME_PRINT_EX(3) | Library Functions Manual | X509_NAME_PRINT_EX(3)

# NAME

`X509_NAME_print_ex`, `X509_NAME_print_ex_fp`, `X509_NAME_oneline` — X509_NAME printing routines

# SYNOPSIS

library “libcrypto”
`#include <openssl/x509.h>`

int
`X509_NAME_print_ex`(BIO *out, const X509_NAME *nm, int indent, unsigned long flags);

int
`X509_NAME_print_ex_fp`(FILE *fp, const X509_NAME *nm, int indent, unsigned long flags);

char *
`X509_NAME_oneline`(const X509_NAME *a, char *buf, int size);

# DESCRIPTION

`X509_NAME_print_ex`() prints a human readable version of nm to BIO out. Each line (for multiline formats) is indented by indent spaces. The output format can be extensively customised by use of the flags parameter.

`X509_NAME_print_ex_fp`() is identical to `X509_NAME_print_ex`() except the output is written to the FILE pointer fp.

`X509_NAME_oneline`() prints an ASCII version of a to buf. If buf is `NULL`, then a buffer is dynamically allocated and returned, and size is ignored. Otherwise, at most size bytes will be written, including the ending NUL, and buf is returned.

`X509_NAME_oneline`() is a legacy function which produces a non-standard output form. It doesn't handle multi-character fields and has various quirks and inconsistencies. Its use is strongly discouraged in new applications.

Although there are a large number of possible flags, for most purposes `XN_FLAG_ONELINE`, `XN_FLAG_MULTILINE`, or `XN_FLAG_RFC2253` will suffice. As noted on the ASN1_STRING_print_ex(3) manual page, for UTF-8 terminals the `ASN1_STRFLGS_ESC_MSB` should be unset: so for example `XN_FLAG_ONELINE` & ~`ASN1_STRFLGS_ESC_MSB` would be used.

The complete set of the flags supported by `X509_NAME_print_ex` is listed below.

Several options can be OR'ed together.

The options `XN_FLAG_SEP_COMMA_PLUS`, `XN_FLAG_SEP_CPLUS_SPC`, `XN_FLAG_SEP_SPLUS_SPC`, and `XN_FLAG_SEP_MULTILINE` determine the field separators to use. Two distinct separators are used between distinct RelativeDistinguishedName components and separate values in the same RDN for a multi-valued RDN. Multi-valued RDNs are currently very rare so the second separator will hardly ever be used.

`XN_FLAG_SEP_COMMA_PLUS` uses comma and plus as separators. `XN_FLAG_SEP_CPLUS_SPC` uses comma and plus with spaces: this is more readable that plain comma and plus. `XN_FLAG_SEP_SPLUS_SPC` uses spaced semicolon and plus. `XN_FLAG_SEP_MULTILINE` uses spaced newline and plus respectively. `XN_FLAG_SEP_MASK` contains the bits used to represent these four options.

If `XN_FLAG_DN_REV` is set, the whole DN is printed in reversed order.

The fields `XN_FLAG_FN_SN`, `XN_FLAG_FN_LN`, `XN_FLAG_FN_OID`, and `XN_FLAG_FN_NONE` determine how a field name is displayed. It will use the short name (e.g. CN), the long name (e.g. commonName), always use OID numerical form (normally OIDs are only used if the field name is not recognised) and no field name, respectively. `XN_FLAG_FN_MASK` contains the bits used to represent these four options.

If `XN_FLAG_SPC_EQ` is set, then spaces will be placed around the ‘`=`’ character separating field names and values.

If `XN_FLAG_DUMP_UNKNOWN_FIELDS` is set, then the encoding of unknown fields is printed instead of the values.

If `XN_FLAG_FN_ALIGN` is set, then field names are padded to 20 characters: this is only of use for multiline format.

Additionally, all the options supported by ASN1_STRING_print_ex(3) can be used to control how each field value is displayed.

In addition a number of options can be set for commonly used formats.

`XN_FLAG_RFC2253` sets options which produce an output compatible with RFC 2253. It is equivalent to `ASN1_STRFLGS_RFC2253` | `XN_FLAG_SEP_COMMA_PLUS` | `XN_FLAG_DN_REV` | `XN_FLAG_FN_SN` | `XN_FLAG_DUMP_UNKNOWN_FIELDS`.

`XN_FLAG_ONELINE` is a more readable one line format which is the same as: `ASN1_STRFLGS_RFC2253` | `ASN1_STRFLGS_ESC_QUOTE` | `XN_FLAG_SEP_CPLUS_SPC` | `XN_FLAG_SPC_EQ` | `XN_FLAG_FN_SN`.

`XN_FLAG_MULTILINE` is a multiline format which is the same as: `ASN1_STRFLGS_ESC_CTRL` | `ASN1_STRFLGS_ESC_MSB` | `XN_FLAG_SEP_MULTILINE` | `XN_FLAG_SPC_EQ` | `XN_FLAG_FN_LN` | `XN_FLAG_FN_ALIGN`.

`XN_FLAG_COMPAT` uses the traditional non-standard SSLeay format.

# RETURN VALUES

`X509_NAME_print_ex`() and `X509_NAME_print_ex_fp`() return 1 on success or 0 on error if `XN_FLAG_COMPAT` is set in flags. Otherwise, they return the number of printed bytes including the indentation or -1 on error.

`X509_NAME_oneline`() returns a valid string on success or `NULL` on error.

# SEE ALSO

ASN1_STRING_print_ex(3), d2i_X509_NAME(3), X509_NAME_get_index_by_NID(3), X509_NAME_new(3)

# HISTORY

`X509_NAME_oneline`() first appeared in SSLeay 0.5.1 and has been available since OpenBSD 2.4.

`X509_NAME_print_ex`() and `X509_NAME_print_ex_fp`() first appeared in OpenSSL 0.9.6 and have been available since OpenBSD 2.9.

June 8, 2025 | Debian