Ssl/bio of OpenSSL_ get_ fd

As long as it is used OpenSSL, There are always things that make people feel overwhelmed . This time it is SSL_get_fd. I created one in a very simple way SSL object , Directly on this object SSL Of accept：

bio = BIO_new(BIO_s_accept());  BIO_set_accept_port(bio, "1234");  BIO_do_accept(bio);  SSL_set_bio(ssl, bio, bio);  SSL_accept(ssl); 

So you don't have to deal with annoying sockaddr 了 . Later, I thought about this SSL The bottom layer of object Association socket On the implementation setsockopt, Take it for granted SSL_get_fd/BIO_get_fd This is very self-evident API. So far, it's great . Then it's not cool , I find setsockiot The descriptor of the final operation is listnen Socket , instead of accept The socket returned . This seems to be API On the level, it is very reasonable , After all bio The parameter of is a BIO_s_accept, And what is associated with it is a listen Socket . Want to get the right accept Returned read / write socket The descriptor , You have to write this ：

[plain] view plaincopyprint? stay CODE View the code slice on the screen and derive it to my code slice

BIO_get_fd(BIO_next(bio), &sd);

BIO_get_fd(BIO_next(bio), &sd); The problem is , You must know this BIO stack How is it arranged to write the above code , The best way to do this is to see OpenSSL Source code .

BIO Of API Design must be designed as get/set_fd Do you ？BIO You have to be with one fd Is it relevant ？memory Type of BIO If get fd Words , What kind of error will it return ？ since BIO Constitute a superimposed IO stack, Then maybe the one at the bottom will be with one UNIX fd Related to , Then why not just go back to the bottom one ？