From aa4d426b4d3527d7e166df1a05058c9a4a0f6683 Mon Sep 17 00:00:00 2001 From: Wojtek Kosior Date: Fri, 30 Apr 2021 00:33:56 +0200 Subject: initial/final commit --- openssl-1.1.0h/ssl/record/README | 74 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 74 insertions(+) create mode 100644 openssl-1.1.0h/ssl/record/README (limited to 'openssl-1.1.0h/ssl/record/README') diff --git a/openssl-1.1.0h/ssl/record/README b/openssl-1.1.0h/ssl/record/README new file mode 100644 index 0000000..987e9fd --- /dev/null +++ b/openssl-1.1.0h/ssl/record/README @@ -0,0 +1,74 @@ +Record Layer Design +=================== + +This file provides some guidance on the thinking behind the design of the +record layer code to aid future maintenance. + +The record layer is divided into a number of components. At the time of writing +there are four: SSL3_RECORD, SSL3_BUFFER, DLTS1_BITMAP and RECORD_LAYER. Each +of these components is defined by: +1) A struct definition of the same name as the component +2) A set of source files that define the functions for that component +3) A set of accessor macros + +All struct definitions are in record.h. The functions and macros are either +defined in record.h or record_locl.h dependent on whether they are intended to +be private to the record layer, or whether they form part of the API to the rest +of libssl. + +The source files map to components as follows: + +dtls1_bitmap.c -> DTLS1_BITMAP component +ssl3_buffer.c -> SSL3_BUFFER component +ssl3_record.c -> SSL3_RECORD component +rec_layer_s3.c, rec_layer_d1.c -> RECORD_LAYER component + +The RECORD_LAYER component is a facade pattern, i.e. it provides a simplified +interface to the record layer for the rest of libssl. The other 3 components are +entirely private to the record layer and therefore should never be accessed +directly by libssl. + +Any component can directly access its own members - they are private to that +component, e.g. ssl3_buffer.c can access members of the SSL3_BUFFER struct +without using a macro. No component can directly access the members of another +component, e.g. ssl3_buffer cannot reach inside the RECORD_LAYER component to +directly access its members. Instead components use accessor macros, so if code +in ssl3_buffer.c wants to access the members of the RECORD_LAYER it uses the +RECORD_LAYER_* macros. + +Conceptually it looks like this: + + libssl + | +---------------------------|-----record.h-------------------------------------- + | + _______V______________ + | | + | RECORD_LAYER | + | | + | rec_layer_s3.c | + | ^ | + | _________|__________ | + || || + || DTLS1_RECORD_LAYER || + || || + || rec_layer_d1.c || + ||____________________|| + |______________________| + record_locl.h ^ ^ ^ + _________________| | |_________________ + | | | + _____V_________ ______V________ _______V________ + | | | | | | + | SSL3_BUFFER | | SSL3_RECORD | | DTLS1_BITMAP | + | |--->| | | | + | ssl3_buffer.c | | ssl3_record.c | | dtls1_bitmap.c | + |_______________| |_______________| |________________| + + +The two RECORD_LAYER source files build on each other, i.e. +the main one is rec_layer_s3.c which provides the core SSL/TLS layer. The second +one is rec_layer_d1.c which builds off of the SSL/TLS code to provide DTLS +specific capabilities. It uses some DTLS specific RECORD_LAYER component members +which should only be accessed from rec_layer_d1.c. These are held in the +DTLS1_RECORD_LAYER struct. -- cgit v1.2.3