#0  0x0000000800ad0c10 in SSL_CTX_get_verify_callback () from /usr/lib/libssl.so.6
(gdb) bt
#0  0x0000000800ad0c10 in SSL_CTX_get_verify_callback () from /usr/lib/libssl.so.6
#1  0x00000000004511d8 in ngx_http_ssl_servername (ssl_conn=0x804422000, ad=0x7fffffffe564, arg=0x0) at src/http/ngx_http_request.c:681
#2  0x0000000800acc8d2 in ssl_check_clienthello_tlsext () from /usr/lib/libssl.so.6
#3  0x0000000800ac42ca in ssl3_get_client_hello () from /usr/lib/libssl.so.6
#4  0x0000000800ac4faf in ssl3_accept () from /usr/lib/libssl.so.6
#5  0x0000000800abcd74 in ssl23_get_client_hello () from /usr/lib/libssl.so.6
#6  0x0000000800abd536 in ssl23_accept () from /usr/lib/libssl.so.6
#7  0x000000000043d149 in ngx_ssl_handshake (c=0x804574b58) at src/event/ngx_event_openssl.c:582
#8  0x0000000000450f3a in ngx_http_ssl_handshake (rev=0x8045a5f50) at src/http/ngx_http_request.c:566
#9  0x0000000000450cdb in ngx_http_init_request (rev=0x8045a5f50) at src/http/ngx_http_request.c:518
#10 0x000000000042d76c in ngx_event_process_posted (cycle=0x80264e050, posted=0x603a00) at src/event/ngx_event_posted.c:39
#11 0x000000000042b375 in ngx_process_events_and_timers (cycle=0x80264e050) at src/event/ngx_event.c:272
#12 0x0000000000437e94 in ngx_worker_process_cycle (cycle=0x80264e050, data=0x0) at src/os/unix/ngx_process_cycle.c:801
#13 0x0000000000435001 in ngx_spawn_process (cycle=0x80264e050, proc=0x437ca0 <ngx_worker_process_cycle>, data=0x0,
    name=0x4d02d9 "worker process", respawn=-3) at src/os/unix/ngx_process.c:196
#14 0x0000000000436d2a in ngx_start_worker_processes (cycle=0x80264e050, n=4, type=-3) at src/os/unix/ngx_process_cycle.c:360
#15 0x00000000004363c9 in ngx_master_process_cycle (cycle=0x80264e050) at src/os/unix/ngx_process_cycle.c:136
#16 0x0000000000407102 in main (argc=1, argv=0x7fffffffed68) at src/core/nginx.c:405
(gdb)