Mitigate strange segfault in tests/client012.phpt

[DaveRandom]

Building on debian stretch against libcurl4-openssl-dev 7.52.1-5+deb9u6 (current) I get a segfault in this test. I have been unable to reproduce it in any other environment, so I assume it is a problem with one of the dependencies rather than this extension (probably openssl, as you will see in a minute) - however it can be mitigated in the extension.

Digging into it, the problem is that SSL_get_SSL_CTX() is returning garbage - it always seems to return 0x19000 - which results in a segfault when the pointer is dereferenced further down. However, if I switch to the pre-7.48 branch (i.e. use CURLINFO_TLS_SESSION instead of CURLINFO_TLS_SSL_PTR) then I get a valid pointer, the data is retrieved correctly, the test passes and there is no segfault. I cannot see any obvious problem with the code in the CURLINFO_TLS_SSL_PTR branch, I can only assume it is an upstream bug - although I cannot find any similar reports against libcurl or openssl either.

Since no following code actually requires the SSL* handle, I propose switching to always use CURLINFO_TLS_SESSION and accessing the SSL_CTX* handle directly. This would be a simplification of the code, and avoids this issue. If a future feature requires the SSL* handle... well, we can cross that bridge when we come to it 😛

For reference, here's the valgrind details of the issue:

==15969== Invalid read of size 8
==15969==    at 0x5D784D0: SSL_CTX_ctrl (in /usr/lib/x86_64-linux-gnu/libssl.so.1.1)
==15969==    by 0xA03A397: php_http_curle_get_info (php_http_client_curl.c:546)
==15969==    by 0xA03A397: php_http_client_curl_getopt (php_http_client_curl.c:2433)
==15969==    by 0xA0360EE: zim_HttpClient_getTransferInfo (php_http_client.c:1148)
==15969==    by 0x4BD79E: execute_ex (in /usr/bin/php7.2-zts)
==15969==    by 0x3EC80C: zend_call_function (in /usr/bin/php7.2-zts)
==15969==    by 0xA062866: php_http_object_method_call (php_http_object.c:112)
==15969==    by 0xA033503: notify (php_http_client.c:980)
==15969==    by 0x2E3A08: spl_iterator_apply (in /usr/bin/php7.2-zts)
==15969==    by 0xA033402: zim_HttpClient_notify (php_http_client.c:1020)
==15969==    by 0x3EC607: zend_call_function (in /usr/bin/php7.2-zts)
==15969==    by 0xA062866: php_http_object_method_call (php_http_object.c:112)
==15969==    by 0xA03367A: handle_progress (php_http_client.c:529)
==15969==  Address 0x19020 is not stack'd, malloc'd or (recently) free'd

[m6w6]

Wild guess: does the issue vanish if *ti is set to NULL?

[DaveRandom]

I will investigate this afternoon