bugfix: stream cosocket getsslctx() bound to wrong FFI symbol

[perfgao]

Summary

In lib/resty/core/socket.lua, the stream branch binds ngx_lua_ffi_socket_getsslctx to ngx_stream_lua_ffi_socket_tcp_get_ssl_pointer — clearly a copy/paste from the getsslpointer block right above it. The probing pcall also references _get_ssl_pointer instead of _get_ssl_ctx.

if pcall(function() return C.ngx_stream_lua_ffi_socket_tcp_get_ssl_pointer end)
then
ngx_lua_ffi_socket_getsslctx = C.ngx_stream_lua_ffi_socket_tcp_get_ssl_pointer
end

Compare with the http branch (lines 103-104), which correctly probes and binds _get_ssl_ctx.

Impact

stream-lua-nginx-module exports both ngx_stream_lua_ffi_socket_tcp_get_ssl_pointer (returns SSL *) and ngx_stream_lua_ffi_socket_tcp_get_ssl_ctx (returns SSL_CTX *). With the current binding, stream cosocket:getsslctx() actually returns an SSL * while callers treat it as SSL_CTX * — undefined behavior / potential segfault when callers dereference fields at SSL_CTX offsets.

Fix

Bind to ngx_stream_lua_ffi_socket_tcp_get_ssl_ctx, mirroring the http branch. The C declaration for _get_ssl_ctx is already present in the stream ffi.cdef block (line 136), so no additional declaration is needed.

Test plan

• Verify stream cosocket:getsslctx() returns a value usable as SSL_CTX * (e.g., SSL_CTX_set_* calls).
• Existing http getsslctx tests continue to pass.