NAME
CRYPTO_THREADID_set_numeric
,
CRYPTO_THREADID_set_pointer
,
CRYPTO_THREADID_set_callback
,
CRYPTO_THREADID_get_callback
,
CRYPTO_THREADID_current
,
CRYPTO_THREADID_cmp
,
CRYPTO_THREADID_cpy
,
CRYPTO_THREADID_hash
,
CRYPTO_num_locks
,
CRYPTO_set_dynlock_create_callback
,
CRYPTO_set_dynlock_lock_callback
,
CRYPTO_set_dynlock_destroy_callback
,
CRYPTO_get_new_dynlockid
,
CRYPTO_destroy_dynlockid
,
CRYPTO_lock
, CRYPTO_w_lock
,
CRYPTO_w_unlock
,
CRYPTO_r_lock
,
CRYPTO_r_unlock
, CRYPTO_add
— OpenSSL thread
support
SYNOPSIS
#include
<openssl/crypto.h>
/* Don't use this structure directly. */ typedef struct crypto_threadid_st { void *ptr; unsigned long val; } CRYPTO_THREADID; /* Only use CRYPTO_THREADID_set_[numeric|pointer]() within callbacks */
void
CRYPTO_THREADID_set_numeric
(CRYPTO_THREADID
*id, unsigned long val);
void
CRYPTO_THREADID_set_pointer
(CRYPTO_THREADID
*id, void *ptr);
int
CRYPTO_THREADID_set_callback
(void
(*threadid_func)(CRYPTO_THREADID *));
void
(*CRYPTO_THREADID_get_callback(void))
(CRYPTO_THREADID
*);
void
CRYPTO_THREADID_current
(CRYPTO_THREADID
*id);
int
CRYPTO_THREADID_cmp
(const
CRYPTO_THREADID *a, const CRYPTO_THREADID
*b);
void
CRYPTO_THREADID_cpy
(CRYPTO_THREADID
*dest, const CRYPTO_THREADID *src);
unsigned long
CRYPTO_THREADID_hash
(const
CRYPTO_THREADID *id);
int
CRYPTO_num_locks
(void);
/* struct CRYPTO_dynlock_value needs to be defined by the user */ struct CRYPTO_dynlock_value;
void
CRYPTO_set_dynlock_create_callback
(struct
CRYPTO_dynlock_value *, (*dyn_create_function)(char
*file, int line));
void
CRYPTO_set_dynlock_lock_callback
(void
(*dyn_lock_function)(int mode, struct CRYPTO_dynlock_value *l, const char
*file, int line));
void
CRYPTO_set_dynlock_destroy_callback
(void
(*dyn_destroy_function)(struct CRYPTO_dynlock_value *l, const char *file,
int line));
int
CRYPTO_get_new_dynlockid
(void);
void
CRYPTO_destroy_dynlockid
(int
i);
void
CRYPTO_lock
(int mode,
int n, const char *file,
int line);
#define CRYPTO_w_lock(type) \ CRYPTO_lock(CRYPTO_LOCK|CRYPTO_WRITE, type, __FILE__, __LINE__) #define CRYPTO_w_unlock(type) \ CRYPTO_lock(CRYPTO_UNLOCK|CRYPTO_WRITE, type, __FILE__, __LINE__) #define CRYPTO_r_lock(type) \ CRYPTO_lock(CRYPTO_LOCK|CRYPTO_READ, type, __FILE__, __LINE__) #define CRYPTO_r_unlock(type) \ CRYPTO_lock(CRYPTO_UNLOCK|CRYPTO_READ, type, __FILE__, __LINE__) #define CRYPTO_add(addr,amount,type) \ CRYPTO_add_lock(addr, amount, type, __FILE__, __LINE__)
DESCRIPTION
OpenSSL can safely be used in multi-threaded applications provided
that at least two callback functions are set,
locking_function
()
and threadid_func
().
locking_function
(int
mode, int n, const char
*file, int line); is needed to perform locking
on shared data structures. Note that OpenSSL uses a number of global data
structures that will be implicitly shared whenever multiple threads use
OpenSSL. Multi-threaded applications will crash at random if it is not
set.
locking_function
()
must be able to handle up to
CRYPTO_num_locks
()
different mutex locks. It sets the n-th lock if
mode includes CRYPTO_LOCK
, and
releases it otherwise.
file and line are the file number of the function setting the lock. They can be useful for debugging.
threadid_func
(CRYPTO_THREADID
*id); is needed to record the currently-executing thread's identifier
into id. The implementation of this callback should
not fill in id directly, but should use
CRYPTO_THREADID_set_numeric
()
if thread IDs are numeric, or
CRYPTO_THREADID_set_pointer
()
if they are pointer-based. If the application does not register such a
callback using
CRYPTO_THREADID_set_callback
(),
then a default implementation is used - on Windows and BeOS this uses the
system's default thread identifying APIs, and on all other platforms it uses
the address of errno. The latter is satisfactory for
thread-safety if and only if the platform has a thread-local error number
facility.
Once
threadid_func
()
is registered, or if the built-in default implementation is to be used,
CRYPTO_THREADID_current
() records the currently-executing thread ID into the given id object.CRYPTO_THREADID_cmp
() compares two thread IDs (returning zero for equality, i.e. the same semantics as memcmp(3)).CRYPTO_THREADID_cpy
() duplicates a thread ID value.CRYPTO_THREADID_hash
() returns a numeric value usable as a hash-table key. This is usually the exact numeric or pointer-based thread ID used internally, however this also handles the unusual case where pointers are larger than long variables and the platform's thread IDs are pointer-based — in this case, mixing is done to attempt to produce a unique numeric value even though it is not as wide as the platform's true thread IDs.
Additionally, OpenSSL supports dynamic locks and, sometimes, some parts of OpenSSL need it for better performance. To enable this, the following is required:
- Three additional callback functions,
dyn_create_function
(),dyn_lock_function
(), anddyn_destroy_function
(). - A structure defined with the data that each lock needs to handle.
struct CRYPTO_dynlock_value has to be defined to contain whatever structure is needed to handle locks.
dyn_create_function
(const
char *file, int line); is needed to create a
lock. Multi-threaded applications might crash at random if it is not
set.
dyn_lock_function
(int
mode, CRYPTO_dynlock *l, const
char *file, int line); is needed to perform
locking off dynamic lock numbered n. Multi-threaded applications might crash
at random if it is not set.
dyn_destroy_function
(CRYPTO_dynlock
*l, const char *file, int
line); is needed to destroy the lock l.
Multi-threaded applications might crash at random if it is not set.
CRYPTO_get_new_dynlockid
()
is used to create locks. It will call
dyn_create_function
() for the actual creation.
CRYPTO_destroy_dynlockid
()
is used to destroy locks. It will call
dyn_destroy_function
() for the actual
destruction.
CRYPTO_lock
()
is used to lock and unlock the locks. mode is a
bitfield describing what should be done with the lock.
n is the number of the lock as returned from
CRYPTO_get_new_dynlockid
().
mode can be combined from the following values. These
values are pairwise exclusive, with undefined behaviour if misused (for
example, CRYPTO_READ
and
CRYPTO_WRITE
should not be used together):
CRYPTO_LOCK 0x01 CRYPTO_UNLOCK 0x02 CRYPTO_READ 0x04 CRYPTO_WRITE 0x08
You can find out if OpenSSL was configured with thread support:
#define OPENSSL_THREAD_DEFINES #include <openssl/opensslconf.h> #if defined(OPENSSL_THREADS) /* thread support enabled */ #else /* no thread support */ #endif
Also, dynamic locks are currently not used internally by OpenSSL, but may do so in the future.
RETURN VALUES
CRYPTO_num_locks
() returns the required
number of locks.
CRYPTO_get_new_dynlockid
() returns the
index to the newly created lock.
The other functions return no values.
EXAMPLES
crypto/threads/mttest.c shows examples of the callback functions on Solaris, Irix and Win32.
SEE ALSO
HISTORY
CRYPTO_set_locking_callback
() is available
in all versions of SSLeay and OpenSSL.
CRYPTO_num_locks
() was added in OpenSSL 0.9.4. All
functions dealing with dynamic locks were added in OpenSSL 0.9.5b-dev.
CRYPTO_THREADID and associated functions were
introduced in OpenSSL 1.0.0 to replace (actually, deprecate) the previous
CRYPTO_set_id_callback
(),
CRYPTO_get_id_callback
(), and
CRYPTO_thread_id
() functions which assumed thread
IDs to always be represented by unsigned long.