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ssl(3) OpenSSL ssl(3)
NAME
SSL - OpenSSL SSL/TLS library
SYNOPSIS
DESCRIPTION
The OpenSSL ssl library implements the Secure Sockets Layer (SSL v2/v3)
and Transport Layer Security (TLS v1) protocols. It provides a rich API
which is documented here.
At first the library must be initialized; see SSL_library_init(3).
Then an SSL_CTX object is created as a framework to establish TLS/SSL
enabled connections (see SSL_CTX_new(3)). Various options regarding
certificates, algorithms etc. can be set in this object.
When a network connection has been created, it can be assigned to an
SSL object. After the SSL object has been created using SSL_new(3),
SSL_set_fd(3) or SSL_set_bio(3) can be used to associate the network
connection with the object.
Then the TLS/SSL handshake is performed using SSL_accept(3) or
SSL_connect(3) respectively. SSL_read(3) and SSL_write(3) are used to
read and write data on the TLS/SSL connection. SSL_shutdown(3) can be
used to shut down the TLS/SSL connection.
DATA STRUCTURES
Currently the OpenSSL ssl library functions deals with the following
data structures:
SSL_METHOD (SSL Method)
That's a dispatch structure describing the internal ssl library
methods/functions which implement the various protocol versions
(SSLv1, SSLv2 and TLSv1). It's needed to create an SSL_CTX.
SSL_CIPHER (SSL Cipher)
This structure holds the algorithm information for a particular
cipher which are a core part of the SSL/TLS protocol. The available
ciphers are configured on a SSL_CTX basis and the actually used
ones are then part of the SSL_SESSION.
SSL_CTX (SSL Context)
That's the global context structure which is created by a server or
client once per program life-time and which holds mainly default
values for the SSL structures which are later created for the
connections.
SSL_SESSION (SSL Session)
This is a structure containing the current TLS/SSL session details
for a connection: SSL_CIPHERs, client and server certificates,
keys, etc.
SSL (SSL Connection)
That's the main SSL/TLS structure which is created by a server or
client per established connection. This actually is the core
structure in the SSL API. Under run-time the application usually
deals with this structure which has links to mostly all other
structures.
HEADER FILES
Currently the OpenSSL ssl library provides the following C header files
containing the prototypes for the data structures and and functions:
ssl.h
That's the common header file for the SSL/TLS API. Include it into
your program to make the API of the ssl library available. It
internally includes both more private SSL headers and headers from
the crypto library. Whenever you need hard-core details on the
internals of the SSL API, look inside this header file.
ssl2.h
That's the sub header file dealing with the SSLv2 protocol only.
Usually you don't have to include it explicitly because it's
already included by ssl.h.
ssl3.h
That's the sub header file dealing with the SSLv3 protocol only.
Usually you don't have to include it explicitly because it's
already included by ssl.h.
ssl23.h
That's the sub header file dealing with the combined use of the
SSLv2 and SSLv3 protocols. Usually you don't have to include it
explicitly because it's already included by ssl.h.
tls1.h
That's the sub header file dealing with the TLSv1 protocol only.
Usually you don't have to include it explicitly because it's
already included by ssl.h.
API FUNCTIONS
Currently the OpenSSL ssl library exports 214 API functions. They are
documented in the following:
DEALING WITH PROTOCOL METHODS
Here we document the various API functions which deal with the SSL/TLS
protocol methods defined in SSL_METHOD structures.
const SSL_METHOD *SSLv23_method(void);
Constructor for the version-flexible SSL_METHOD structure for
clients, servers or both. See SSL_CTX_new(3) for details.
const SSL_METHOD *SSLv23_client_method(void);
Constructor for the version-flexible SSL_METHOD structure for
clients.
const SSL_METHOD *SSLv23_client_method(void);
Constructor for the version-flexible SSL_METHOD structure for
servers.
const SSL_METHOD *TLSv1_2_method(void);
Constructor for the TLSv1.2 SSL_METHOD structure for clients,
servers or both.
const SSL_METHOD *TLSv1_2_client_method(void);
Constructor for the TLSv1.2 SSL_METHOD structure for clients.
const SSL_METHOD *TLSv1_2_server_method(void);
Constructor for the TLSv1.2 SSL_METHOD structure for servers.
const SSL_METHOD *TLSv1_1_method(void);
Constructor for the TLSv1.1 SSL_METHOD structure for clients,
servers or both.
const SSL_METHOD *TLSv1_1_client_method(void);
Constructor for the TLSv1.1 SSL_METHOD structure for clients.
const SSL_METHOD *TLSv1_1_server_method(void);
Constructor for the TLSv1.1 SSL_METHOD structure for servers.
const SSL_METHOD *TLSv1_method(void);
Constructor for the TLSv1 SSL_METHOD structure for clients, servers
or both.
const SSL_METHOD *TLSv1_client_method(void);
Constructor for the TLSv1 SSL_METHOD structure for clients.
const SSL_METHOD *TLSv1_server_method(void);
Constructor for the TLSv1 SSL_METHOD structure for servers.
const SSL_METHOD *SSLv3_method(void);
Constructor for the SSLv3 SSL_METHOD structure for clients, servers
or both.
const SSL_METHOD *SSLv3_client_method(void);
Constructor for the SSLv3 SSL_METHOD structure for clients.
const SSL_METHOD *SSLv3_server_method(void);
Constructor for the SSLv3 SSL_METHOD structure for servers.
const SSL_METHOD *SSLv2_method(void);
Constructor for the SSLv2 SSL_METHOD structure for clients, servers
or both.
const SSL_METHOD *SSLv2_client_method(void);
Constructor for the SSLv2 SSL_METHOD structure for clients.
const SSL_METHOD *SSLv2_server_method(void);
Constructor for the SSLv2 SSL_METHOD structure for servers.
DEALING WITH CIPHERS
Here we document the various API functions which deal with the SSL/TLS
ciphers defined in SSL_CIPHER structures.
char *SSL_CIPHER_description(SSL_CIPHER *cipher, char *buf, int len);
Write a string to buf (with a maximum size of len) containing a
human readable description of cipher. Returns buf.
int SSL_CIPHER_get_bits(SSL_CIPHER *cipher, int *alg_bits);
Determine the number of bits in cipher. Because of export crippled
ciphers there are two bits: The bits the algorithm supports in
general (stored to alg_bits) and the bits which are actually used
(the return value).
const char *SSL_CIPHER_get_name(SSL_CIPHER *cipher);
Return the internal name of cipher as a string. These are the
various strings defined by the SSL2_TXT_xxx, SSL3_TXT_xxx and
TLS1_TXT_xxx definitions in the header files.
char *SSL_CIPHER_get_version(SSL_CIPHER *cipher);
Returns a string like ""TLSv1/SSLv3"" or ""SSLv2"" which indicates
the SSL/TLS protocol version to which cipher belongs (i.e. where it
was defined in the specification the first time).
DEALING WITH PROTOCOL CONTEXTS
Here we document the various API functions which deal with the SSL/TLS
protocol context defined in the SSL_CTX structure.
int SSL_CTX_add_client_CA(SSL_CTX *ctx, X509 *x);
long SSL_CTX_add_extra_chain_cert(SSL_CTX *ctx, X509 *x509);
int SSL_CTX_add_session(SSL_CTX *ctx, SSL_SESSION *c);
int SSL_CTX_check_private_key(const SSL_CTX *ctx);
long SSL_CTX_ctrl(SSL_CTX *ctx, int cmd, long larg, char *parg);
void SSL_CTX_flush_sessions(SSL_CTX *s, long t);
void SSL_CTX_free(SSL_CTX *a);
char *SSL_CTX_get_app_data(SSL_CTX *ctx);
X509_STORE *SSL_CTX_get_cert_store(SSL_CTX *ctx);
STACK *SSL_CTX_get_client_CA_list(const SSL_CTX *ctx);
int (*SSL_CTX_get_client_cert_cb(SSL_CTX *ctx))(SSL *ssl, X509 **x509,
EVP_PKEY **pkey);
void SSL_CTX_get_default_read_ahead(SSL_CTX *ctx);
char *SSL_CTX_get_ex_data(const SSL_CTX *s, int idx);
int SSL_CTX_get_ex_new_index(long argl, char *argp, int
(*new_func);(void), int (*dup_func)(void), void (*free_func)(void))
void (*SSL_CTX_get_info_callback(SSL_CTX *ctx))(SSL *ssl, int cb, int
ret);
int SSL_CTX_get_quiet_shutdown(const SSL_CTX *ctx);
void SSL_CTX_get_read_ahead(SSL_CTX *ctx);
int SSL_CTX_get_session_cache_mode(SSL_CTX *ctx);
long SSL_CTX_get_timeout(const SSL_CTX *ctx);
int (*SSL_CTX_get_verify_callback(const SSL_CTX *ctx))(int ok,
X509_STORE_CTX *ctx);
int SSL_CTX_get_verify_mode(SSL_CTX *ctx);
int SSL_CTX_load_verify_locations(SSL_CTX *ctx, char *CAfile, char
*CApath);
long SSL_CTX_need_tmp_RSA(SSL_CTX *ctx);
SSL_CTX *SSL_CTX_new(const SSL_METHOD *meth);
int SSL_CTX_remove_session(SSL_CTX *ctx, SSL_SESSION *c);
int SSL_CTX_sess_accept(SSL_CTX *ctx);
int SSL_CTX_sess_accept_good(SSL_CTX *ctx);
int SSL_CTX_sess_accept_renegotiate(SSL_CTX *ctx);
int SSL_CTX_sess_cache_full(SSL_CTX *ctx);
int SSL_CTX_sess_cb_hits(SSL_CTX *ctx);
int SSL_CTX_sess_connect(SSL_CTX *ctx);
int SSL_CTX_sess_connect_good(SSL_CTX *ctx);
int SSL_CTX_sess_connect_renegotiate(SSL_CTX *ctx);
int SSL_CTX_sess_get_cache_size(SSL_CTX *ctx);
SSL_SESSION *(*SSL_CTX_sess_get_get_cb(SSL_CTX *ctx))(SSL *ssl,
unsigned char *data, int len, int *copy);
int (*SSL_CTX_sess_get_new_cb(SSL_CTX *ctx)(SSL *ssl, SSL_SESSION
*sess);
void (*SSL_CTX_sess_get_remove_cb(SSL_CTX *ctx)(SSL_CTX *ctx,
SSL_SESSION *sess);
int SSL_CTX_sess_hits(SSL_CTX *ctx);
int SSL_CTX_sess_misses(SSL_CTX *ctx);
int SSL_CTX_sess_number(SSL_CTX *ctx);
void SSL_CTX_sess_set_cache_size(SSL_CTX *ctx,t);
void SSL_CTX_sess_set_get_cb(SSL_CTX *ctx, SSL_SESSION *(*cb)(SSL *ssl,
unsigned char *data, int len, int *copy));
void SSL_CTX_sess_set_new_cb(SSL_CTX *ctx, int (*cb)(SSL *ssl,
SSL_SESSION *sess));
void SSL_CTX_sess_set_remove_cb(SSL_CTX *ctx, void (*cb)(SSL_CTX *ctx,
SSL_SESSION *sess));
int SSL_CTX_sess_timeouts(SSL_CTX *ctx);
LHASH *SSL_CTX_sessions(SSL_CTX *ctx);
void SSL_CTX_set_app_data(SSL_CTX *ctx, void *arg);
void SSL_CTX_set_cert_store(SSL_CTX *ctx, X509_STORE *cs);
void SSL_CTX_set_cert_verify_cb(SSL_CTX *ctx, int (*cb)(), char *arg)
int SSL_CTX_set_cipher_list(SSL_CTX *ctx, char *str);
void SSL_CTX_set_client_CA_list(SSL_CTX *ctx, STACK *list);
void SSL_CTX_set_client_cert_cb(SSL_CTX *ctx, int (*cb)(SSL *ssl, X509
**x509, EVP_PKEY **pkey));
void SSL_CTX_set_default_passwd_cb(SSL_CTX *ctx, int (*cb);(void))
void SSL_CTX_set_default_read_ahead(SSL_CTX *ctx, int m);
int SSL_CTX_set_default_verify_paths(SSL_CTX *ctx);
int SSL_CTX_set_ex_data(SSL_CTX *s, int idx, char *arg);
void SSL_CTX_set_info_callback(SSL_CTX *ctx, void (*cb)(SSL *ssl, int
cb, int ret));
void SSL_CTX_set_msg_callback(SSL_CTX *ctx, void (*cb)(int write_p, int
version, int content_type, const void *buf, size_t len, SSL *ssl, void
*arg));
void SSL_CTX_set_msg_callback_arg(SSL_CTX *ctx, void *arg);
void SSL_CTX_set_options(SSL_CTX *ctx, unsigned long op);
void SSL_CTX_set_quiet_shutdown(SSL_CTX *ctx, int mode);
void SSL_CTX_set_read_ahead(SSL_CTX *ctx, int m);
void SSL_CTX_set_session_cache_mode(SSL_CTX *ctx, int mode);
int SSL_CTX_set_ssl_version(SSL_CTX *ctx, const SSL_METHOD *meth);
void SSL_CTX_set_timeout(SSL_CTX *ctx, long t);
long SSL_CTX_set_tmp_dh(SSL_CTX* ctx, DH *dh);
long SSL_CTX_set_tmp_dh_callback(SSL_CTX *ctx, DH *(*cb)(void));
long SSL_CTX_set_tmp_rsa(SSL_CTX *ctx, RSA *rsa);
SSL_CTX_set_tmp_rsa_callback
"long SSL_CTX_set_tmp_rsa_callback(SSL_CTX *ctx, RSA *(*cb)(SSL
*ssl, int export, int keylength));"
Sets the callback which will be called when a temporary private key
is required. The "export" flag will be set if the reason for
needing a temp key is that an export ciphersuite is in use, in
which case, "keylength" will contain the required keylength in
bits. Generate a key of appropriate size (using ???) and return it.
SSL_set_tmp_rsa_callback
long SSL_set_tmp_rsa_callback(SSL *ssl, RSA *(*cb)(SSL *ssl, int
export, int keylength));
The same as SSL_CTX_set_tmp_rsa_callback, except it operates on an
SSL session instead of a context.
void SSL_CTX_set_verify(SSL_CTX *ctx, int mode, int (*cb);(void))
int SSL_CTX_use_PrivateKey(SSL_CTX *ctx, EVP_PKEY *pkey);
int SSL_CTX_use_PrivateKey_ASN1(int type, SSL_CTX *ctx, unsigned char
*d, long len);
int SSL_CTX_use_PrivateKey_file(SSL_CTX *ctx, char *file, int type);
int SSL_CTX_use_RSAPrivateKey(SSL_CTX *ctx, RSA *rsa);
int SSL_CTX_use_RSAPrivateKey_ASN1(SSL_CTX *ctx, unsigned char *d, long
len);
int SSL_CTX_use_RSAPrivateKey_file(SSL_CTX *ctx, char *file, int type);
int SSL_CTX_use_certificate(SSL_CTX *ctx, X509 *x);
int SSL_CTX_use_certificate_ASN1(SSL_CTX *ctx, int len, unsigned char
*d);
int SSL_CTX_use_certificate_file(SSL_CTX *ctx, char *file, int type);
X509 *SSL_CTX_get0_certificate(const SSL_CTX *ctx);
EVP_PKEY *SSL_CTX_get0_privatekey(const SSL_CTX *ctx);
void SSL_CTX_set_psk_client_callback(SSL_CTX *ctx, unsigned int
(*callback)(SSL *ssl, const char *hint, char *identity, unsigned int
max_identity_len, unsigned char *psk, unsigned int max_psk_len));
int SSL_CTX_use_psk_identity_hint(SSL_CTX *ctx, const char *hint);
void SSL_CTX_set_psk_server_callback(SSL_CTX *ctx, unsigned int
(*callback)(SSL *ssl, const char *identity, unsigned char *psk, int
max_psk_len));
DEALING WITH SESSIONS
Here we document the various API functions which deal with the SSL/TLS
sessions defined in the SSL_SESSION structures.
int SSL_SESSION_cmp(const SSL_SESSION *a, const SSL_SESSION *b);
void SSL_SESSION_free(SSL_SESSION *ss);
char *SSL_SESSION_get_app_data(SSL_SESSION *s);
char *SSL_SESSION_get_ex_data(const SSL_SESSION *s, int idx);
int SSL_SESSION_get_ex_new_index(long argl, char *argp, int
(*new_func);(void), int (*dup_func)(void), void (*free_func)(void))
long SSL_SESSION_get_time(const SSL_SESSION *s);
long SSL_SESSION_get_timeout(const SSL_SESSION *s);
unsigned long SSL_SESSION_hash(const SSL_SESSION *a);
SSL_SESSION *SSL_SESSION_new(void);
int SSL_SESSION_print(BIO *bp, const SSL_SESSION *x);
int SSL_SESSION_print_fp(FILE *fp, const SSL_SESSION *x);
void SSL_SESSION_set_app_data(SSL_SESSION *s, char *a);
int SSL_SESSION_set_ex_data(SSL_SESSION *s, int idx, char *arg);
long SSL_SESSION_set_time(SSL_SESSION *s, long t);
long SSL_SESSION_set_timeout(SSL_SESSION *s, long t);
DEALING WITH CONNECTIONS
Here we document the various API functions which deal with the SSL/TLS
connection defined in the SSL structure.
int SSL_accept(SSL *ssl);
int SSL_add_dir_cert_subjects_to_stack(STACK *stack, const char *dir);
int SSL_add_file_cert_subjects_to_stack(STACK *stack, const char
*file);
int SSL_add_client_CA(SSL *ssl, X509 *x);
char *SSL_alert_desc_string(int value);
char *SSL_alert_desc_string_long(int value);
char *SSL_alert_type_string(int value);
char *SSL_alert_type_string_long(int value);
int SSL_check_private_key(const SSL *ssl);
void SSL_clear(SSL *ssl);
long SSL_clear_num_renegotiations(SSL *ssl);
int SSL_connect(SSL *ssl);
void SSL_copy_session_id(SSL *t, const SSL *f);
long SSL_ctrl(SSL *ssl, int cmd, long larg, char *parg);
int SSL_do_handshake(SSL *ssl);
SSL *SSL_dup(SSL *ssl);
STACK *SSL_dup_CA_list(STACK *sk);
void SSL_free(SSL *ssl);
SSL_CTX *SSL_get_SSL_CTX(const SSL *ssl);
char *SSL_get_app_data(SSL *ssl);
X509 *SSL_get_certificate(const SSL *ssl);
const char *SSL_get_cipher(const SSL *ssl);
int SSL_get_cipher_bits(const SSL *ssl, int *alg_bits);
char *SSL_get_cipher_list(const SSL *ssl, int n);
char *SSL_get_cipher_name(const SSL *ssl);
char *SSL_get_cipher_version(const SSL *ssl);
STACK *SSL_get_ciphers(const SSL *ssl);
STACK *SSL_get_client_CA_list(const SSL *ssl);
SSL_CIPHER *SSL_get_current_cipher(SSL *ssl);
long SSL_get_default_timeout(const SSL *ssl);
int SSL_get_error(const SSL *ssl, int i);
char *SSL_get_ex_data(const SSL *ssl, int idx);
int SSL_get_ex_data_X509_STORE_CTX_idx(void);
int SSL_get_ex_new_index(long argl, char *argp, int (*new_func);(void),
int (*dup_func)(void), void (*free_func)(void))
int SSL_get_fd(const SSL *ssl);
void (*SSL_get_info_callback(const SSL *ssl);)()
STACK *SSL_get_peer_cert_chain(const SSL *ssl);
X509 *SSL_get_peer_certificate(const SSL *ssl);
EVP_PKEY *SSL_get_privatekey(const SSL *ssl);
int SSL_get_quiet_shutdown(const SSL *ssl);
BIO *SSL_get_rbio(const SSL *ssl);
int SSL_get_read_ahead(const SSL *ssl);
SSL_SESSION *SSL_get_session(const SSL *ssl);
char *SSL_get_shared_ciphers(const SSL *ssl, char *buf, int len);
int SSL_get_shutdown(const SSL *ssl);
const SSL_METHOD *SSL_get_ssl_method(SSL *ssl);
int SSL_get_state(const SSL *ssl);
long SSL_get_time(const SSL *ssl);
long SSL_get_timeout(const SSL *ssl);
int (*SSL_get_verify_callback(const SSL *ssl))(int,X509_STORE_CTX *)
int SSL_get_verify_mode(const SSL *ssl);
long SSL_get_verify_result(const SSL *ssl);
char *SSL_get_version(const SSL *ssl);
BIO *SSL_get_wbio(const SSL *ssl);
int SSL_in_accept_init(SSL *ssl);
int SSL_in_before(SSL *ssl);
int SSL_in_connect_init(SSL *ssl);
int SSL_in_init(SSL *ssl);
int SSL_is_init_finished(SSL *ssl);
STACK *SSL_load_client_CA_file(char *file);
void SSL_load_error_strings(void);
SSL *SSL_new(SSL_CTX *ctx);
long SSL_num_renegotiations(SSL *ssl);
int SSL_peek(SSL *ssl, void *buf, int num);
int SSL_pending(const SSL *ssl);
int SSL_read(SSL *ssl, void *buf, int num);
int SSL_renegotiate(SSL *ssl);
char *SSL_rstate_string(SSL *ssl);
char *SSL_rstate_string_long(SSL *ssl);
long SSL_session_reused(SSL *ssl);
void SSL_set_accept_state(SSL *ssl);
void SSL_set_app_data(SSL *ssl, char *arg);
void SSL_set_bio(SSL *ssl, BIO *rbio, BIO *wbio);
int SSL_set_cipher_list(SSL *ssl, char *str);
void SSL_set_client_CA_list(SSL *ssl, STACK *list);
void SSL_set_connect_state(SSL *ssl);
int SSL_set_ex_data(SSL *ssl, int idx, char *arg);
int SSL_set_fd(SSL *ssl, int fd);
void SSL_set_info_callback(SSL *ssl, void (*cb);(void))
void SSL_set_msg_callback(SSL *ctx, void (*cb)(int write_p, int
version, int content_type, const void *buf, size_t len, SSL *ssl, void
*arg));
void SSL_set_msg_callback_arg(SSL *ctx, void *arg);
void SSL_set_options(SSL *ssl, unsigned long op);
void SSL_set_quiet_shutdown(SSL *ssl, int mode);
void SSL_set_read_ahead(SSL *ssl, int yes);
int SSL_set_rfd(SSL *ssl, int fd);
int SSL_set_session(SSL *ssl, SSL_SESSION *session);
void SSL_set_shutdown(SSL *ssl, int mode);
int SSL_set_ssl_method(SSL *ssl, const SSL_METHOD *meth);
void SSL_set_time(SSL *ssl, long t);
void SSL_set_timeout(SSL *ssl, long t);
void SSL_set_verify(SSL *ssl, int mode, int (*callback);(void))
void SSL_set_verify_result(SSL *ssl, long arg);
int SSL_set_wfd(SSL *ssl, int fd);
int SSL_shutdown(SSL *ssl);
int SSL_state(const SSL *ssl);
char *SSL_state_string(const SSL *ssl);
char *SSL_state_string_long(const SSL *ssl);
long SSL_total_renegotiations(SSL *ssl);
int SSL_use_PrivateKey(SSL *ssl, EVP_PKEY *pkey);
int SSL_use_PrivateKey_ASN1(int type, SSL *ssl, unsigned char *d, long
len);
int SSL_use_PrivateKey_file(SSL *ssl, char *file, int type);
int SSL_use_RSAPrivateKey(SSL *ssl, RSA *rsa);
int SSL_use_RSAPrivateKey_ASN1(SSL *ssl, unsigned char *d, long len);
int SSL_use_RSAPrivateKey_file(SSL *ssl, char *file, int type);
int SSL_use_certificate(SSL *ssl, X509 *x);
int SSL_use_certificate_ASN1(SSL *ssl, int len, unsigned char *d);
int SSL_use_certificate_file(SSL *ssl, char *file, int type);
int SSL_version(const SSL *ssl);
int SSL_want(const SSL *ssl);
int SSL_want_nothing(const SSL *ssl);
int SSL_want_read(const SSL *ssl);
int SSL_want_write(const SSL *ssl);
int SSL_want_x509_lookup(const SSL *ssl);
int SSL_write(SSL *ssl, const void *buf, int num);
void SSL_set_psk_client_callback(SSL *ssl, unsigned int (*callback)(SSL
*ssl, const char *hint, char *identity, unsigned int max_identity_len,
unsigned char *psk, unsigned int max_psk_len));
int SSL_use_psk_identity_hint(SSL *ssl, const char *hint);
void SSL_set_psk_server_callback(SSL *ssl, unsigned int (*callback)(SSL
*ssl, const char *identity, unsigned char *psk, int max_psk_len));
const char *SSL_get_psk_identity_hint(SSL *ssl);
const char *SSL_get_psk_identity(SSL *ssl);
SEE ALSO
openssl(1), crypto(3), SSL_accept(3), SSL_clear(3), SSL_connect(3),
SSL_CIPHER_get_name(3), SSL_COMP_add_compression_method(3),
SSL_CTX_add_extra_chain_cert(3), SSL_CTX_add_session(3),
SSL_CTX_ctrl(3), SSL_CTX_flush_sessions(3),
SSL_CTX_get_ex_new_index(3), SSL_CTX_get_verify_mode(3),
SSL_CTX_load_verify_locations(3) SSL_CTX_new(3),
SSL_CTX_sess_number(3), SSL_CTX_sess_set_cache_size(3),
SSL_CTX_sess_set_get_cb(3), SSL_CTX_sessions(3),
SSL_CTX_set_cert_store(3), SSL_CTX_set_cert_verify_callback(3),
SSL_CTX_set_cipher_list(3), SSL_CTX_set_client_CA_list(3),
SSL_CTX_set_client_cert_cb(3), SSL_CTX_set_default_passwd_cb(3),
SSL_CTX_set_generate_session_id(3), SSL_CTX_set_info_callback(3),
SSL_CTX_set_max_cert_list(3), SSL_CTX_set_mode(3),
SSL_CTX_set_msg_callback(3), SSL_CTX_set_options(3),
SSL_CTX_set_quiet_shutdown(3), SSL_CTX_set_read_ahead(3),
SSL_CTX_set_session_cache_mode(3), SSL_CTX_set_session_id_context(3),
SSL_CTX_set_ssl_version(3), SSL_CTX_set_timeout(3),
SSL_CTX_set_tmp_rsa_callback(3), SSL_CTX_set_tmp_dh_callback(3),
SSL_CTX_set_verify(3), SSL_CTX_use_certificate(3),
SSL_alert_type_string(3), SSL_do_handshake(3), SSL_get_SSL_CTX(3),
SSL_get_ciphers(3), SSL_get_client_CA_list(3),
SSL_get_default_timeout(3), SSL_get_error(3),
SSL_get_ex_data_X509_STORE_CTX_idx(3), SSL_get_ex_new_index(3),
SSL_get_fd(3), SSL_get_peer_cert_chain(3), SSL_get_rbio(3),
SSL_get_session(3), SSL_get_verify_result(3), SSL_get_version(3),
SSL_library_init(3), SSL_load_client_CA_file(3), SSL_new(3),
SSL_pending(3), SSL_read(3), SSL_rstate_string(3),
SSL_session_reused(3), SSL_set_bio(3), SSL_set_connect_state(3),
SSL_set_fd(3), SSL_set_session(3), SSL_set_shutdown(3),
SSL_shutdown(3), SSL_state_string(3), SSL_want(3), SSL_write(3),
SSL_SESSION_free(3), SSL_SESSION_get_ex_new_index(3),
SSL_SESSION_get_time(3), d2i_SSL_SESSION(3),
SSL_CTX_set_psk_client_callback(3), SSL_CTX_use_psk_identity_hint(3),
SSL_get_psk_identity(3)
HISTORY
The ssl(3) document appeared in OpenSSL 0.9.2
1.0.2h 2016-05-03 ssl(3)
SSL_CONF_cmd(3) OpenSSL SSL_CONF_cmd(3)
NAME
SSL_CONF_cmd - send configuration command
SYNOPSIS
#include <openssl/ssl.h>
int SSL_CONF_cmd(SSL_CONF_CTX *cctx, const char *cmd, const char *value);
int SSL_CONF_cmd_value_type(SSL_CONF_CTX *cctx, const char *cmd);
int SSL_CONF_finish(SSL_CONF_CTX *cctx);
DESCRIPTION
The function SSL_CONF_cmd() performs configuration operation cmd with
optional parameter value on ctx. Its purpose is to simplify application
configuration of SSL_CTX or SSL structures by providing a common
framework for command line options or configuration files.
SSL_CONF_cmd_value_type() returns the type of value that cmd refers to.
The function SSL_CONF_finish() must be called after all configuration
operations have been completed. It is used to finalise any operations
or to process defaults.
SUPPORTED COMMAND LINE COMMANDS
Currently supported cmd names for command lines (i.e. when the flag
SSL_CONF_CMDLINE is set) are listed below. Note: all cmd names are case
sensitive. Unless otherwise stated commands can be used by both clients
and servers and the value parameter is not used. The default prefix for
command line commands is - and that is reflected below.
-sigalgs
This sets the supported signature algorithms for TLS v1.2. For
clients this value is used directly for the supported signature
algorithms extension. For servers it is used to determine which
signature algorithms to support.
The value argument should be a colon separated list of signature
algorithms in order of decreasing preference of the form
algorithm+hash. algorithm is one of RSA, DSA or ECDSA and hash is a
supported algorithm OID short name such as SHA1, SHA224, SHA256,
SHA384 of SHA512. Note: algorithm and hash names are case
sensitive.
If this option is not set then all signature algorithms supported
by the OpenSSL library are permissible.
-client_sigalgs
This sets the supported signature algorithms associated with client
authentication for TLS v1.2. For servers the value is used in the
supported signature algorithms field of a certificate request. For
clients it is used to determine which signature algorithm to with
the client certificate. If a server does not request a certificate
this option has no effect.
The syntax of value is identical to -sigalgs. If not set then the
value set for -sigalgs will be used instead.
-curves
This sets the supported elliptic curves. For clients the curves are
sent using the supported curves extension. For servers it is used
to determine which curve to use. This setting affects curves used
for both signatures and key exchange, if applicable.
The value argument is a colon separated list of curves. The curve
can be either the NIST name (e.g. P-256) or an OpenSSL OID name
(e.g prime256v1). Curve names are case sensitive.
-named_curve
This sets the temporary curve used for ephemeral ECDH modes. Only
used by servers
The value argument is a curve name or the special value auto which
picks an appropriate curve based on client and server preferences.
The curve can be either the NIST name (e.g. P-256) or an OpenSSL
OID name (e.g prime256v1). Curve names are case sensitive.
-cipher
Sets the cipher suite list to value. Note: syntax checking of value
is currently not performed unless a SSL or SSL_CTX structure is
associated with cctx.
-cert
Attempts to use the file value as the certificate for the
appropriate context. It currently uses
SSL_CTX_use_certificate_chain_file() if an SSL_CTX structure is set
or SSL_use_certificate_file() with filetype PEM if an SSL structure
is set. This option is only supported if certificate operations are
permitted.
-key
Attempts to use the file value as the private key for the
appropriate context. This option is only supported if certificate
operations are permitted. Note: if no -key option is set then a
private key is not loaded: it does not currently use the -cert
file.
-dhparam
Attempts to use the file value as the set of temporary DH
parameters for the appropriate context. This option is only
supported if certificate operations are permitted.
-no_ssl2, -no_ssl3, -no_tls1, -no_tls1_1, -no_tls1_2
Disables protocol support for SSLv2, SSLv3, TLSv1.0, TLSv1.1 or
TLSv1.2 by setting the corresponding options SSL_OP_NO_SSLv2,
SSL_OP_NO_SSLv3, SSL_OP_NO_TLSv1, SSL_OP_NO_TLSv1_1 and
SSL_OP_NO_TLSv1_2 respectively.
-bugs
Various bug workarounds are set, same as setting SSL_OP_ALL.
-no_comp
Disables support for SSL/TLS compression, same as setting
SSL_OP_NO_COMPRESS.
-no_ticket
Disables support for session tickets, same as setting
SSL_OP_NO_TICKET.
-serverpref
Use server and not client preference order when determining which
cipher suite, signature algorithm or elliptic curve to use for an
incoming connection. Equivalent to
SSL_OP_CIPHER_SERVER_PREFERENCE. Only used by servers.
-no_resumption_on_reneg
set SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION flag. Only used
by servers.
-legacyrenegotiation
permits the use of unsafe legacy renegotiation. Equivalent to
setting SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION.
-legacy_server_connect, -no_legacy_server_connect
permits or prohibits the use of unsafe legacy renegotiation for
OpenSSL clients only. Equivalent to setting or clearing
SSL_OP_LEGACY_SERVER_CONNECT. Set by default.
-strict
enables strict mode protocol handling. Equivalent to setting
SSL_CERT_FLAG_TLS_STRICT.
-debug_broken_protocol
disables various checks and permits several kinds of broken
protocol behaviour for testing purposes: it should NEVER be used in
anything other than a test environment. Only supported if OpenSSL
is configured with -DOPENSSL_SSL_DEBUG_BROKEN_PROTOCOL.
SUPPORTED CONFIGURATION FILE COMMANDS
Currently supported cmd names for configuration files (i.e. when the
flag SSL_CONF_FLAG_FILE is set) are listed below. All configuration
file cmd names and are case insensitive so signaturealgorithms is
recognised as well as SignatureAlgorithms. Unless otherwise stated the
value names are also case insensitive.
Note: the command prefix (if set) alters the recognised cmd values.
CipherString
Sets the cipher suite list to value. Note: syntax checking of value
is currently not performed unless an SSL or SSL_CTX structure is
associated with cctx.
Certificate
Attempts to use the file value as the certificate for the
appropriate context. It currently uses
SSL_CTX_use_certificate_chain_file() if an SSL_CTX structure is set
or SSL_use_certificate_file() with filetype PEM if an SSL structure
is set. This option is only supported if certificate operations are
permitted.
PrivateKey
Attempts to use the file value as the private key for the
appropriate context. This option is only supported if certificate
operations are permitted. Note: if no -key option is set then a
private key is not loaded: it does not currently use the
Certificate file.
ServerInfoFile
Attempts to use the file value in the "serverinfo" extension using
the function SSL_CTX_use_serverinfo_file.
DHParameters
Attempts to use the file value as the set of temporary DH
parameters for the appropriate context. This option is only
supported if certificate operations are permitted.
SignatureAlgorithms
This sets the supported signature algorithms for TLS v1.2. For
clients this value is used directly for the supported signature
algorithms extension. For servers it is used to determine which
signature algorithms to support.
The value argument should be a colon separated list of signature
algorithms in order of decreasing preference of the form
algorithm+hash. algorithm is one of RSA, DSA or ECDSA and hash is a
supported algorithm OID short name such as SHA1, SHA224, SHA256,
SHA384 of SHA512. Note: algorithm and hash names are case
sensitive.
If this option is not set then all signature algorithms supported
by the OpenSSL library are permissible.
ClientSignatureAlgorithms
This sets the supported signature algorithms associated with client
authentication for TLS v1.2. For servers the value is used in the
supported signature algorithms field of a certificate request. For
clients it is used to determine which signature algorithm to with
the client certificate.
The syntax of value is identical to SignatureAlgorithms. If not set
then the value set for SignatureAlgorithms will be used instead.
Curves
This sets the supported elliptic curves. For clients the curves are
sent using the supported curves extension. For servers it is used
to determine which curve to use. This setting affects curves used
for both signatures and key exchange, if applicable.
The value argument is a colon separated list of curves. The curve
can be either the NIST name (e.g. P-256) or an OpenSSL OID name
(e.g prime256v1). Curve names are case sensitive.
ECDHParameters
This sets the temporary curve used for ephemeral ECDH modes. Only
used by servers
The value argument is a curve name or the special value Automatic
which picks an appropriate curve based on client and server
preferences. The curve can be either the NIST name (e.g. P-256) or
an OpenSSL OID name (e.g prime256v1). Curve names are case
sensitive.
Protocol
The supported versions of the SSL or TLS protocol.
The value argument is a comma separated list of supported protocols
to enable or disable. If an protocol is preceded by - that version
is disabled. Currently supported protocol values are SSLv2, SSLv3,
TLSv1, TLSv1.1 and TLSv1.2. All protocol versions other than SSLv2
are enabled by default. To avoid inadvertent enabling of SSLv2,
when SSLv2 is disabled, it is not possible to enable it via the
Protocol command.
Options
The value argument is a comma separated list of various flags to
set. If a flag string is preceded - it is disabled. See the
SSL_CTX_set_options function for more details of individual
options.
Each option is listed below. Where an operation is enabled by
default the -flag syntax is needed to disable it.
SessionTicket: session ticket support, enabled by default. Inverse
of SSL_OP_NO_TICKET: that is -SessionTicket is the same as setting
SSL_OP_NO_TICKET.
Compression: SSL/TLS compression support, enabled by default.
Inverse of SSL_OP_NO_COMPRESSION.
EmptyFragments: use empty fragments as a countermeasure against a
SSL 3.0/TLS 1.0 protocol vulnerability affecting CBC ciphers. It is
set by default. Inverse of SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS.
Bugs: enable various bug workarounds. Same as SSL_OP_ALL.
DHSingle: enable single use DH keys, set by default. Inverse of
SSL_OP_DH_SINGLE. Only used by servers.
ECDHSingle enable single use ECDH keys, set by default. Inverse of
SSL_OP_ECDH_SINGLE. Only used by servers.
ServerPreference use server and not client preference order when
determining which cipher suite, signature algorithm or elliptic
curve to use for an incoming connection. Equivalent to
SSL_OP_CIPHER_SERVER_PREFERENCE. Only used by servers.
NoResumptionOnRenegotiation set
SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION flag. Only used by
servers.
UnsafeLegacyRenegotiation permits the use of unsafe legacy
renegotiation. Equivalent to
SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION.
UnsafeLegacyServerConnect permits the use of unsafe legacy
renegotiation for OpenSSL clients only. Equivalent to
SSL_OP_LEGACY_SERVER_CONNECT. Set by default.
SUPPORTED COMMAND TYPES
The function SSL_CONF_cmd_value_type() currently returns one of the
following types:
SSL_CONF_TYPE_UNKNOWN
The cmd string is unrecognised, this return value can be use to
flag syntax errors.
SSL_CONF_TYPE_STRING
The value is a string without any specific structure.
SSL_CONF_TYPE_FILE
The value is a file name.
SSL_CONF_TYPE_DIR
The value is a directory name.
NOTES
The order of operations is significant. This can be used to set either
defaults or values which cannot be overridden. For example if an
application calls:
SSL_CONF_cmd(ctx, "Protocol", "-SSLv3");
SSL_CONF_cmd(ctx, userparam, uservalue);
it will disable SSLv3 support by default but the user can override it.
If however the call sequence is:
SSL_CONF_cmd(ctx, userparam, uservalue);
SSL_CONF_cmd(ctx, "Protocol", "-SSLv3");
then SSLv3 is always disabled and attempt to override this by the user
are ignored.
By checking the return code of SSL_CTX_cmd() it is possible to query if
a given cmd is recognised, this is useful is SSL_CTX_cmd() values are
mixed with additional application specific operations.
For example an application might call SSL_CTX_cmd() and if it returns
-2 (unrecognised command) continue with processing of application
specific commands.
Applications can also use SSL_CTX_cmd() to process command lines though
the utility function SSL_CTX_cmd_argv() is normally used instead. One
way to do this is to set the prefix to an appropriate value using
SSL_CONF_CTX_set1_prefix(), pass the current argument to cmd and the
following argument to value (which may be NULL).
In this case if the return value is positive then it is used to skip
that number of arguments as they have been processed by SSL_CTX_cmd().
If -2 is returned then cmd is not recognised and application specific
arguments can be checked instead. If -3 is returned a required argument
is missing and an error is indicated. If 0 is returned some other error
occurred and this can be reported back to the user.
The function SSL_CONF_cmd_value_type() can be used by applications to
check for the existence of a command or to perform additional syntax
checking or translation of the command value. For example if the return
value is SSL_CONF_TYPE_FILE an application could translate a relative
pathname to an absolute pathname.
EXAMPLES
Set supported signature algorithms:
SSL_CONF_cmd(ctx, "SignatureAlgorithms", "ECDSA+SHA256:RSA+SHA256:DSA+SHA256");
Enable all protocols except SSLv3 and SSLv2:
SSL_CONF_cmd(ctx, "Protocol", "ALL,-SSLv3,-SSLv2");
Only enable TLSv1.2:
SSL_CONF_cmd(ctx, "Protocol", "-ALL,TLSv1.2");
Disable TLS session tickets:
SSL_CONF_cmd(ctx, "Options", "-SessionTicket");
Set supported curves to P-256, P-384:
SSL_CONF_cmd(ctx, "Curves", "P-256:P-384");
Set automatic support for any elliptic curve for key exchange:
SSL_CONF_cmd(ctx, "ECDHParameters", "Automatic");
RETURN VALUES
SSL_CONF_cmd() returns 1 if the value of cmd is recognised and value is
NOT used and 2 if both cmd and value are used. In other words it
returns the number of arguments processed. This is useful when
processing command lines.
A return value of -2 means cmd is not recognised.
A return value of -3 means cmd is recognised and the command requires a
value but value is NULL.
A return code of 0 indicates that both cmd and value are valid but an
error occurred attempting to perform the operation: for example due to
an error in the syntax of value in this case the error queue may
provide additional information.
SSL_CONF_finish() returns 1 for success and 0 for failure.
SEE ALSO
SSL_CONF_CTX_new(3), SSL_CONF_CTX_set_flags(3),
SSL_CONF_CTX_set1_prefix(3), SSL_CONF_CTX_set_ssl_ctx(3),
SSL_CONF_cmd_argv(3)
HISTORY
SSL_CONF_cmd() was first added to OpenSSL 1.0.2
1.0.2h 2016-05-03 SSL_CONF_cmd(3)