Migration of default BIO_METHOD from OpenSSL 1.0.2 to 1.1.1

Question

I'm trying to port my application code from OpenSSL 1.0.2 to 1.1.1 and I came across a change I can't seem to understand.

In 1.0.2 we have replaced the default bread and bwrite methods of BIO_s_socket by calling:

orig_bread = BIO_s_socket()->bread;
orig_bwrite = BIO_s_socket()->bwrite;
BIO_s_socket()->bread = my_bread;
BIO_s_socket()->bwrite = my_bwrite;

However, in OpenSSL 1.1.1 BIO_s_socket() is said to return const BIO_METHOD* instead of BIO_METHOD* . How can I change the default behavior in this version?

Edit: (...and if can't do it anymore, how do I set a bread and bwrite per ssl connection?)

Answer 1

I'm trying to port my application code from OpenSSL 1.0.2 to 1.1.0

Firstly I recommend you move to 1.1.1 not 1.1.0. 1.1.1 is a Long Term Support version (LTS) and will be supported until 2023. 1.1.0 support ends later this year.

You need to create a custom BIO_METHOD. In brief you create one using BIO_meth_new() and then set custom read and write functions using BIO_meth_set_read() and BIO_meth_set_write() . Depending on what your BIO_METHOD does you may need to call other set functions. They are all documented here:

https://www.openssl.org/docs/man1.1.1/man3/BIO_meth_new.html