1threads(3) OpenSSL threads(3)
2
6 CRYPTO_THREADID_set_callback, CRYPTO_THREADID_get_callback,
7 CRYPTO_THREADID_current, CRYPTO_THREADID_cmp, CRYPTO_THREADID_cpy,
8 CRYPTO_THREADID_hash, CRYPTO_set_locking_callback, CRYPTO_num_locks,
9 CRYPTO_set_dynlock_create_callback, CRYPTO_set_dynlock_lock_callback,
10 CRYPTO_set_dynlock_destroy_callback, CRYPTO_get_new_dynlockid,
11 CRYPTO_destroy_dynlockid, CRYPTO_lock - OpenSSL thread support
12
14 #include <openssl/crypto.h>
15 /* Don't use this structure directly. */
17 typedef struct crypto_threadid_st
18 {
19 void *ptr;
20 unsigned long val;
21 } CRYPTO_THREADID;
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);
33 int CRYPTO_num_locks(void);
35 /* struct CRYPTO_dynlock_value needs to be defined by the user */
37 struct CRYPTO_dynlock_value;
38 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));
46 int CRYPTO_get_new_dynlockid(void);
48 void CRYPTO_destroy_dynlockid(int i);
50 void CRYPTO_lock(int mode, int n, const char *file, int line);
52 #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__)
63
65 OpenSSL can generally be used safely in multi-threaded applications
66 provided that at least two callback functions are set, the
67 locking_function and threadid_func. Note that OpenSSL is not
68 completely thread-safe, and unfortunately not all global resources have
69 the necessary locks. Further, the thread-safety does not extend to
70 things like multiple threads using the same SSL object at the same
71 time.
72 locking_function(int mode, int n, const char *file, int line) is needed
74 to perform locking on shared data structures. (Note that OpenSSL uses
75 a number of global data structures that will be implicitly shared
76 whenever multiple threads use OpenSSL.) Multi-threaded applications
77 will crash at random if it is not set.
78 locking_function() must be able to handle up to CRYPTO_num_locks()
80 different mutex locks. It sets the n-th lock if mode & CRYPTO_LOCK, and
81 releases it otherwise.
82 file and line are the file number of the function setting the lock.
84 They can be useful for debugging.
85 threadid_func(CRYPTO_THREADID *id) is needed to record the currently-
87 executing thread's identifier into id. The implementation of this
88 callback should not fill in id directly, but should use
89 CRYPTO_THREADID_set_numeric() if thread IDs are numeric, or
90 CRYPTO_THREADID_set_pointer() if they are pointer-based. If the
91 application does not register such a callback using
92 CRYPTO_THREADID_set_callback(), then a default implementation is used -
93 on Windows and BeOS this uses the system's default thread identifying
94 APIs, and on all other platforms it uses the address of errno. The
95 latter is satisfactory for thread-safety if and only if the platform
96 has a thread-local error number facility.
97 Once threadid_func() is registered, or if the built-in default
99 implementation is to be used;
100 · CRYPTO_THREADID_current() records the currently-executing thread ID
102 into the given id object.
103 · CRYPTO_THREADID_cmp() compares two thread IDs (returning zero for
105 equality, ie. the same semantics as memcmp()).
106 · CRYPTO_THREADID_cpy() duplicates a thread ID value,
108 · CRYPTO_THREADID_hash() returns a numeric value usable as a hash-
110 table key. This is usually the exact numeric or pointer-based
111 thread ID used internally, however this also handles the unusual
112 case where pointers are larger than 'long' variables and the
113 platform's thread IDs are pointer-based - in this case, mixing is
114 done to attempt to produce a unique numeric value even though it is
115 not as wide as the platform's true thread IDs.
116 Additionally, OpenSSL supports dynamic locks, and sometimes, some parts
118 of OpenSSL need it for better performance. To enable this, the
119 following is required:
120 · Three additional callback function, dyn_create_function,
122 dyn_lock_function and dyn_destroy_function.
123 · A structure defined with the data that each lock needs to handle.
125 struct CRYPTO_dynlock_value has to be defined to contain whatever
127 structure is needed to handle locks.
128 dyn_create_function(const char *file, int line) is needed to create a
130 lock. Multi-threaded applications might crash at random if it is not
131 set.
132 dyn_lock_function(int mode, CRYPTO_dynlock *l, const char *file, int
134 line) is needed to perform locking off dynamic lock numbered n. Multi-
135 threaded applications might crash at random if it is not set.
136 dyn_destroy_function(CRYPTO_dynlock *l, const char *file, int line) is
138 needed to destroy the lock l. Multi-threaded applications might crash
139 at random if it is not set.
140 CRYPTO_get_new_dynlockid() is used to create locks. It will call
142 dyn_create_function for the actual creation.
143 CRYPTO_destroy_dynlockid() is used to destroy locks. It will call
145 dyn_destroy_function for the actual destruction.
146 CRYPTO_lock() is used to lock and unlock the locks. mode is a bitfield
148 describing what should be done with the lock. n is the number of the
149 lock as returned from CRYPTO_get_new_dynlockid(). mode can be combined
150 from the following values. These values are pairwise exclusive, with
151 undefined behaviour if misused (for example, CRYPTO_READ and
152 CRYPTO_WRITE should not be used together):
153 CRYPTO_LOCK 0x01
155 CRYPTO_UNLOCK 0x02
156 CRYPTO_READ 0x04
157 CRYPTO_WRITE 0x08
158
160 CRYPTO_num_locks() returns the required number of locks.
161 CRYPTO_get_new_dynlockid() returns the index to the newly created lock.
163 The other functions return no values.
165
167 You can find out if OpenSSL was configured with thread support:
168 #define OPENSSL_THREAD_DEFINES
170 #include <openssl/opensslconf.h>
171 #if defined(OPENSSL_THREADS)
172 // thread support enabled
173 #else
174 // no thread support
175 #endif
176 Also, dynamic locks are currently not used internally by OpenSSL, but
178 may do so in the future.
179
181 crypto/threads/mttest.c shows examples of the callback functions on
182 Solaris, Irix and Win32.
183
185 CRYPTO_set_locking_callback() is available in all versions of SSLeay
186 and OpenSSL. CRYPTO_num_locks() was added in OpenSSL 0.9.4. All
187 functions dealing with dynamic locks were added in OpenSSL 0.9.5b-dev.
188 CRYPTO_THREADID and associated functions were introduced in OpenSSL
189 1.0.0 to replace (actually, deprecate) the previous
190 CRYPTO_set_id_callback(), CRYPTO_get_id_callback(), and
191 CRYPTO_thread_id() functions which assumed thread IDs to always be
192 represented by 'unsigned long'.
193
195 crypto(3)
1961.0.2o 2020-01-28 threads(3)