SSL_CONF_CTX_set1_prefix.3ssl man page
SSL_CONF_CTX_set1_prefix — Set configuration context command prefix
#include <openssl/ssl.h> unsigned int SSL_CONF_CTX_set1_prefix(SSL_CONF_CTX *cctx, const char *prefix);
The function SSL_CONF_CTX_set1_prefix() sets the command prefix of cctx to prefix. If prefix is NULL it is restored to the default value.
Command prefixes alter the commands recognised by subsequent SSL_CTX_cmd() calls. For example for files, if the prefix "SSL" is set then command names such as "SSLProtocol", "SSLOptions" etc. are recognised instead of "Protocol" and "Options". Similarly for command lines if the prefix is "--ssl-" then "--ssl-no_tls1_2" is recognised instead of "-no_tls1_2".
If the SSL_CONF_FLAG_CMDLINE flag is set then prefix checks are case sensitive and "-" is the default. In the unlikely even an application explicitly wants to set no prefix it must be explicitly set to "".
If the SSL_CONF_FLAG_FILE flag is set then prefix checks are case insensitive and no prefix is the default.
SSL_CONF_CTX_set1_prefix() returns 1 for success and 0 for failure.
SSL_CONF_CTX_new(3), SSL_CONF_CTX_set_flags(3), SSL_CONF_CTX_set_ssl_ctx(3), SSL_CONF_cmd(3), SSL_CONF_cmd_argv(3)
These functions were first added to OpenSSL 1.0.2