SSL_CTX_use_serverinfo.3ssl - Man Page

use serverinfo extension

Synopsis

 #include <openssl/ssl.h>

 int SSL_CTX_use_serverinfo_ex(SSL_CTX *ctx, unsigned int version,
                               const unsigned char *serverinfo,
                               size_t serverinfo_length);

 int SSL_CTX_use_serverinfo(SSL_CTX *ctx, const unsigned char *serverinfo,
                            size_t serverinfo_length);

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

Description

These functions load “serverinfo” TLS extensions into the SSL_CTX. A “serverinfo” extension is returned in response to an empty ClientHello Extension.

SSL_CTX_use_serverinfo_ex() loads one or more serverinfo extensions from a byte array into ctx. The version parameter specifies the format of the byte array provided in *serverinfo which is of length serverinfo_length.

If version is SSL_SERVERINFOV2 then the extensions in the array must consist of a 4-byte context, a 2-byte Extension Type, a 2-byte length, and then length bytes of extension_data. The context and type values have the same meaning as for SSL_CTX_add_custom_ext(3). If serverinfo is being loaded for extensions to be added to a Certificate message, then the extension will only be added for the first certificate in the message (which is always the end-entity certificate).

If version is SSL_SERVERINFOV1 then the extensions in the array must consist of a 2-byte Extension Type, a 2-byte length, and then length bytes of extension_data. The type value has the same meaning as for SSL_CTX_add_custom_ext(3). The following default context value will be used in this case:

 SSL_EXT_TLS1_2_AND_BELOW_ONLY | SSL_EXT_CLIENT_HELLO
 | SSL_EXT_TLS1_2_SERVER_HELLO | SSL_EXT_IGNORE_ON_RESUMPTION

SSL_CTX_use_serverinfo() does the same thing as SSL_CTX_use_serverinfo_ex() except that there is no version parameter so a default version of SSL_SERVERINFOV1 is used instead.

SSL_CTX_use_serverinfo_file() loads one or more serverinfo extensions from file into ctx.  The extensions must be in PEM format.  Each extension must be in a format as described above for SSL_CTX_use_serverinfo_ex().  Each PEM extension name must begin with the phrase “BEGIN SERVERINFOV2 FOR ” for SSL_SERVERINFOV2 data or “BEGIN SERVERINFO FOR ” for SSL_SERVERINFOV1 data.

If more than one certificate (RSA/DSA) is installed using SSL_CTX_use_certificate(), the serverinfo extension will be loaded into the last certificate installed.  If e.g. the last item was a RSA certificate, the loaded serverinfo extension data will be loaded for that certificate.  To use the serverinfo extension for multiple certificates, SSL_CTX_use_serverinfo() needs to be called multiple times, once after each time a certificate is loaded via a call to SSL_CTX_use_certificate().

Return Values

On success, the functions return 1. On failure, the functions return 0.  Check out the error stack to find out the reason.

Referenced By

The man pages SSL_CTX_use_serverinfo_ex.3ssl(3) and SSL_CTX_use_serverinfo_file.3ssl(3) are aliases of SSL_CTX_use_serverinfo.3ssl(3).

2021-02-23 1.1.1j OpenSSL