As per https://github.com/kvspb/nginx-auth-ldap/issues/138#issuecomment-317625746
the issue is that:
* nginx compiles with `-Werror` (treating warnings as errors)
* CentOS 6 has OpenSSL 1.0.1e and so the LDAP module has a warning on compile
* CentOS 6 has GCC 4.4. GCC treats `#pragma GCC diagnostic warning "-Wcpp"` as itself an error and thus skips the statement, leading the the `#warning` still being an error.
This adds version-checking to the warning options and the warning
itself. This means that no warning is issued at compile time on this
type of platform, but warnings are still emitted when starting Nginx
without certificate verification, so it isn't as though the issue has
been hidden.
When inserting the same request to waiting_requests queue twice, the queue will be broken.
In addition, the following segmentation fault occurs at the second ngx_http_auth_ldap_return_connection()
if the nginx binary was compiled with --with-debug.
By this fix, ngx_http_auth_ldap_get_connection() will not insert the same request.
* debug messages at the moment nginx dumped core
====
2016/07/26 13:19:09 [debug] 4299#0: *2 http_auth_ldap: Authentication loop (phase=0, iteration=0)
2016/07/26 13:19:09 [debug] 4299#0: *2 event timer add: 3: 10000:1469506759827
2016/07/26 13:19:09 [debug] 4299#0: *2 http_auth_ldap: request_timeout=10000
2016/07/26 13:19:09 [debug] 4299#0: *2 http_auth_ldap: Authentication loop (phase=1, iteration=0)
2016/07/26 13:19:09 [debug] 4299#0: *2 http_auth_ldap: Wants a free connection to "test_ldap"
2016/07/26 13:19:09 [debug] 4299#0: *2 http_auth_ldap: No connection available at the moment, waiting...
2016/07/26 13:19:09 [debug] 4299#0: *2 http run request: "/portal/Image?"
2016/07/26 13:19:09 [debug] 4299#0: *2 access phase: 6
2016/07/26 13:19:09 [debug] 4299#0: *2 http_auth_ldap: Authentication loop (phase=1, iteration=0)
2016/07/26 13:19:09 [debug] 4299#0: *2 http_auth_ldap: Wants a free connection to "test_ldap"
2016/07/26 13:19:09 [debug] 4299#0: *2 http_auth_ldap: No connection available at the moment, waiting...
<snip>
2016/07/26 13:19:09 [debug] 4299#0: *5 http_auth_ldap: Authentication loop (phase=6, iteration=1)
2016/07/26 13:19:09 [debug] 4299#0: *5 event timer del: 12: 1469506759826
2016/07/26 13:19:09 [debug] 4299#0: http_auth_ldap: Marking the connection to "test_ldap" as free
<snip>
2016/07/26 13:19:09 [debug] 4299#0: *2 http_auth_ldap: Authentication loop (phase=6, iteration=1)
2016/07/26 13:19:09 [debug] 4299#0: *2 event timer del: 3: 1469506759827
2016/07/26 13:19:09 [debug] 4299#0: http_auth_ldap: Marking the connection to "test_ldap" as free
2016/07/26 13:19:09 [notice] 4298#0: signal 17 (SIGCHLD) received
2016/07/26 13:19:09 [alert] 4298#0: worker process 4299 exited on signal 11 (core dumped)
====
* backtrace
====
Program terminated with signal SIGSEGV, Segmentation fault.
#0 0x0000000000491b73 in ngx_http_auth_ldap_return_connection (c=0x26a84e8) at /tmp/test/nginx-1.11.2/../nginx-auth-ldap/ngx_http_auth_ldap_module.c:1117
1117 ngx_queue_remove(q);
(gdb) bt
#0 0x0000000000491b73 in ngx_http_auth_ldap_return_connection (c=0x26a84e8) at /tmp/test/nginx-1.11.2/../nginx-auth-ldap/ngx_http_auth_ldap_module.c:1117
#1 0x000000000049496a in ngx_http_auth_ldap_authenticate (conf=<optimized out>, ctx=0x26e4698, r=0x26e35a0)
at /tmp/test/nginx-1.11.2/../nginx-auth-ldap/ngx_http_auth_ldap_module.c:1902
#2 ngx_http_auth_ldap_handler (r=0x26e35a0) at /tmp/test/nginx-1.11.2/../nginx-auth-ldap/ngx_http_auth_ldap_module.c:1717
#3 0x0000000000446c38 in ngx_http_core_access_phase (r=<optimized out>, ph=0x26a7f48) at src/http/ngx_http_core_module.c:1071
#4 0x00000000004428a3 in ngx_http_core_run_phases (r=r@entry=0x26e35a0) at src/http/ngx_http_core_module.c:845
#5 0x0000000000491ab7 in ngx_http_auth_ldap_wake_request (r=0x26e35a0) at /tmp/test/nginx-1.11.2/../nginx-auth-ldap/ngx_http_auth_ldap_module.c:1063
#6 0x0000000000491c44 in ngx_http_auth_ldap_reply_connection (c=c@entry=0x26a84e8, error_code=0, error_msg=<optimized out>)
at /tmp/test/nginx-1.11.2/../nginx-auth-ldap/ngx_http_auth_ldap_module.c:1141
#7 0x00000000004956b8 in ngx_http_auth_ldap_read_handler (rev=0x265d500) at /tmp/test/nginx-1.11.2/../nginx-auth-ldap/ngx_http_auth_ldap_module.c:1486
#8 0x00000000004384fe in ngx_epoll_process_events (cycle=0x26594e0, timer=<optimized out>, flags=<optimized out>) at src/event/modules/ngx_epoll_module.c:900
#9 0x000000000042ea85 in ngx_process_events_and_timers (cycle=cycle@entry=0x26594e0) at src/event/ngx_event.c:242
#10 0x0000000000435fe0 in ngx_worker_process_cycle (cycle=0x26594e0, data=<optimized out>) at src/os/unix/ngx_process_cycle.c:753
#11 0x0000000000434942 in ngx_spawn_process (cycle=cycle@entry=0x26594e0, proc=proc@entry=0x435f3d <ngx_worker_process_cycle>, data=data@entry=0x0,
name=name@entry=0x49abb7 "worker process", respawn=respawn@entry=-3) at src/os/unix/ngx_process.c:198
#12 0x000000000043613d in ngx_start_worker_processes (cycle=cycle@entry=0x26594e0, n=1, type=type@entry=-3) at src/os/unix/ngx_process_cycle.c:358
#13 0x0000000000436bd6 in ngx_master_process_cycle (cycle=cycle@entry=0x26594e0) at src/os/unix/ngx_process_cycle.c:130
#14 0x000000000041168b in main (argc=<optimized out>, argv=<optimized out>) at src/core/nginx.c:367
====
Valery Komarov
Landry Breuil
Kirill Kartinkin
David Beitey
Benjamin Hudgens
Andreas Peters
Gou Zhuang
József Makai
oli
Mikhail Zaytsev
dkiser
Rinat Ibragimov
Mitrousis, Vasileios (AMOS SE)
Michal Humpula
ERAMOTO Masaya
Xander Smeets
Victor Hahn
Valery Komarov
Marcin Deranek