5 CRYPTO_THREADID_set_callback, CRYPTO_THREADID_get_callback,
6 CRYPTO_THREADID_current, CRYPTO_THREADID_cmp, CRYPTO_THREADID_cpy,
7 CRYPTO_THREADID_hash, CRYPTO_set_locking_callback, CRYPTO_num_locks,
8 CRYPTO_set_dynlock_create_callback, CRYPTO_set_dynlock_lock_callback,
9 CRYPTO_set_dynlock_destroy_callback, CRYPTO_get_new_dynlockid,
10 CRYPTO_destroy_dynlockid, CRYPTO_lock - OpenSSL thread support
14 #include <openssl/crypto.h>
16 /* Don't use this structure directly. */
17 typedef struct crypto_threadid_st
22 /* Only use CRYPTO_THREADID_set_[numeric|pointer]() within callbacks */
23 void CRYPTO_THREADID_set_numeric(CRYPTO_THREADID *id, unsigned long val);
24 void CRYPTO_THREADID_set_pointer(CRYPTO_THREADID *id, void *ptr);
25 int CRYPTO_THREADID_set_callback(void (*threadid_func)(CRYPTO_THREADID *));
26 void (*CRYPTO_THREADID_get_callback(void))(CRYPTO_THREADID *);
27 void CRYPTO_THREADID_current(CRYPTO_THREADID *id);
28 int CRYPTO_THREADID_cmp(const CRYPTO_THREADID *a,
29 const CRYPTO_THREADID *b);
30 void CRYPTO_THREADID_cpy(CRYPTO_THREADID *dest,
31 const CRYPTO_THREADID *src);
32 unsigned long CRYPTO_THREADID_hash(const CRYPTO_THREADID *id);
34 int CRYPTO_num_locks(void);
36 /* struct CRYPTO_dynlock_value needs to be defined by the user */
37 struct CRYPTO_dynlock_value;
39 void CRYPTO_set_dynlock_create_callback(struct CRYPTO_dynlock_value *
40 (*dyn_create_function)(char *file, int line));
41 void CRYPTO_set_dynlock_lock_callback(void (*dyn_lock_function)
42 (int mode, struct CRYPTO_dynlock_value *l,
43 const char *file, int line));
44 void CRYPTO_set_dynlock_destroy_callback(void (*dyn_destroy_function)
45 (struct CRYPTO_dynlock_value *l, const char *file, int line));
47 int CRYPTO_get_new_dynlockid(void);
49 void CRYPTO_destroy_dynlockid(int i);
51 void CRYPTO_lock(int mode, int n, const char *file, int line);
53 #define CRYPTO_w_lock(type) \
54 CRYPTO_lock(CRYPTO_LOCK|CRYPTO_WRITE,type,__FILE__,__LINE__)
55 #define CRYPTO_w_unlock(type) \
56 CRYPTO_lock(CRYPTO_UNLOCK|CRYPTO_WRITE,type,__FILE__,__LINE__)
57 #define CRYPTO_r_lock(type) \
58 CRYPTO_lock(CRYPTO_LOCK|CRYPTO_READ,type,__FILE__,__LINE__)
59 #define CRYPTO_r_unlock(type) \
60 CRYPTO_lock(CRYPTO_UNLOCK|CRYPTO_READ,type,__FILE__,__LINE__)
61 #define CRYPTO_add(addr,amount,type) \
62 CRYPTO_add_lock(addr,amount,type,__FILE__,__LINE__)
66 OpenSSL can generally be used safely in multi-threaded applications provided
67 that at least two callback functions are set, the locking_function and
69 Note that OpenSSL is not completely thread-safe, and unfortunately not all
70 global resources have the necessary locks.
71 Further, the thread-safety does not extend to things like multiple threads
72 using the same B<SSL> object at the same time.
74 locking_function(int mode, int n, const char *file, int line) is
75 needed to perform locking on shared data structures.
76 (Note that OpenSSL uses a number of global data structures that
77 will be implicitly shared whenever multiple threads use OpenSSL.)
78 Multi-threaded applications will crash at random if it is not set.
80 locking_function() must be able to handle up to CRYPTO_num_locks()
81 different mutex locks. It sets the B<n>-th lock if B<mode> &
82 B<CRYPTO_LOCK>, and releases it otherwise.
84 B<file> and B<line> are the file number of the function setting the
85 lock. They can be useful for debugging.
87 threadid_func(CRYPTO_THREADID *id) is needed to record the currently-executing
88 thread's identifier into B<id>. The implementation of this callback should not
89 fill in B<id> directly, but should use CRYPTO_THREADID_set_numeric() if thread
90 IDs are numeric, or CRYPTO_THREADID_set_pointer() if they are pointer-based.
91 If the application does not register such a callback using
92 CRYPTO_THREADID_set_callback(), then a default implementation is used - on
93 Windows and BeOS this uses the system's default thread identifying APIs, and on
94 all other platforms it uses the address of B<errno>. The latter is satisfactory
95 for thread-safety if and only if the platform has a thread-local error number
98 Once threadid_func() is registered, or if the built-in default implementation is
104 CRYPTO_THREADID_current() records the currently-executing thread ID into the
108 CRYPTO_THREADID_cmp() compares two thread IDs (returning zero for equality, ie.
109 the same semantics as memcmp()).
112 CRYPTO_THREADID_cpy() duplicates a thread ID value,
115 CRYPTO_THREADID_hash() returns a numeric value usable as a hash-table key. This
116 is usually the exact numeric or pointer-based thread ID used internally, however
117 this also handles the unusual case where pointers are larger than 'long'
118 variables and the platform's thread IDs are pointer-based - in this case, mixing
119 is done to attempt to produce a unique numeric value even though it is not as
120 wide as the platform's true thread IDs.
124 Additionally, OpenSSL supports dynamic locks, and sometimes, some parts
125 of OpenSSL need it for better performance. To enable this, the following
131 Three additional callback function, dyn_create_function, dyn_lock_function
132 and dyn_destroy_function.
135 A structure defined with the data that each lock needs to handle.
139 struct CRYPTO_dynlock_value has to be defined to contain whatever structure
140 is needed to handle locks.
142 dyn_create_function(const char *file, int line) is needed to create a
143 lock. Multi-threaded applications might crash at random if it is not set.
145 dyn_lock_function(int mode, CRYPTO_dynlock *l, const char *file, int line)
146 is needed to perform locking off dynamic lock numbered n. Multi-threaded
147 applications might crash at random if it is not set.
149 dyn_destroy_function(CRYPTO_dynlock *l, const char *file, int line) is
150 needed to destroy the lock l. Multi-threaded applications might crash at
151 random if it is not set.
153 CRYPTO_get_new_dynlockid() is used to create locks. It will call
154 dyn_create_function for the actual creation.
156 CRYPTO_destroy_dynlockid() is used to destroy locks. It will call
157 dyn_destroy_function for the actual destruction.
159 CRYPTO_lock() is used to lock and unlock the locks. mode is a bitfield
160 describing what should be done with the lock. n is the number of the
161 lock as returned from CRYPTO_get_new_dynlockid(). mode can be combined
162 from the following values. These values are pairwise exclusive, with
163 undefined behaviour if misused (for example, CRYPTO_READ and CRYPTO_WRITE
164 should not be used together):
173 CRYPTO_num_locks() returns the required number of locks.
175 CRYPTO_get_new_dynlockid() returns the index to the newly created lock.
177 The other functions return no values.
181 You can find out if OpenSSL was configured with thread support:
183 #define OPENSSL_THREAD_DEFINES
184 #include <openssl/opensslconf.h>
185 #if defined(OPENSSL_THREADS)
186 // thread support enabled
191 Also, dynamic locks are currently not used internally by OpenSSL, but
192 may do so in the future.
196 B<crypto/threads/mttest.c> shows examples of the callback functions on
197 Solaris, Irix and Win32.
201 CRYPTO_set_locking_callback() is
202 available in all versions of SSLeay and OpenSSL.
203 CRYPTO_num_locks() was added in OpenSSL 0.9.4.
204 All functions dealing with dynamic locks were added in OpenSSL 0.9.5b-dev.
205 B<CRYPTO_THREADID> and associated functions were introduced in OpenSSL 1.0.0
206 to replace (actually, deprecate) the previous CRYPTO_set_id_callback(),
207 CRYPTO_get_id_callback(), and CRYPTO_thread_id() functions which assumed
208 thread IDs to always be represented by 'unsigned long'.
212 L<crypto(3)|crypto(3)>