OSSL_HTTP_REQ_CTX_exchange
resp = OSSL_HTTP_REQ_CTX_exchange(rctx);
mem = OSSL_HTTP_REQ_CTX_exchange(ctx);
BIO *OSSL_HTTP_REQ_CTX_exchange(OSSL_HTTP_REQ_CTX *rctx);
mem = OSSL_HTTP_REQ_CTX_exchange(rctx);