When an invalid TLS configuration is applied (such as the conf_commands
feature), nxt_cert_store_get() creates a buffer to send a certificate request
to the main process and adds its default completion handler to an asynchronous
queue to free the allocated buffer. However, if configuration fails,
nxt_router_conf_error() removes the memory pool used to allocate the buffer,
causing a crash when the completion handler is dispatched.
Assertion "src/nxt_buf.c:208 assertion failed: data == b->parent" is triggered
when is NXT_DEBUG enabled in the configure script.
This patch uses a reference counter to retain the memory pool and redefines the
completion handler to free the buffer before releasing the memory pool.
The certificate is selected by matching the arriving SNI to the common name and
the alternatives names. If no certificate matches the name, the first bundle in
the array is chosen.
Andrey Suvorov