Is libssh2 designed to be used safely in a multi threaded program?
Parts of the code I've read thus far make me think the answer could is
yes.
However, I think I've found at least one non re-entrant peace of code in
openssl.c in _libssh2_rsa_new_private and _libssh2_dsa_new_private. I
mean
the code below :
if (!EVP_get_cipherbyname("des")) {
/* If this cipher isn't loaded it's a pretty good indication that none
are.
* I have *NO DOUBT* that there's a better way to deal with this
($#&%#$(%$#(
* Someone buy me an OpenSSL manual and I'll read up on it.
*/
OpenSSL_add_all_ciphers();
}
As far as I known, OpenSSL_add_all_ciphers is not thread safe. Actually,
it does
not mean OpenSSL can't be use in a multi threaded application. It just
means
special care have to be taken. A way is to call
OpenSSL_add_all_ciphers() or similar
functions like OpenSSL_add_all_digests() and
OpenSSL_add_all_algorithms() in the program
main thread early at program initialization.
So, could it be possible to have a special initialization function for
libssh2 library
that would do all the non re-entrant but necessary initializations one
could call early
in main before spawning new threads?
For example:
int libssh2_library_init(void)
{
/* If build with OpenSSL, add all ciphers. */
OpenSSL_add_all_ciphers();
/* Eventually, other initializations... (libgrcrypt maybe ?) */
...
}
then in main() :
{
if (libssh2_library_init() != 0) {
print some error;
exit(EXIT_FAILURE);
}
...
start other threads that make calls to libssh2 functions
}
BTW, this would make the code below
if (!EVP_get_cipherbyname("des")) {
/* If this cipher isn't loaded it's a pretty good indication that none
are.
* I have *NO DOUBT* that there's a better way to deal with this
($#&%#$(%$#(
* Someone buy me an OpenSSL manual and I'll read up on it.
*/
OpenSSL_add_all_ciphers();
}
unnecessary.
JL
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