mirror of
https://github.com/openssl/openssl.git
synced 2024-12-03 05:41:46 +08:00
706457b7bd
Apart from public and internal header files, there is a third type called local header files, which are located next to source files in the source directory. Currently, they have different suffixes like '*_lcl.h', '*_local.h', or '*_int.h' This commit changes the different suffixes to '*_local.h' uniformly. Reviewed-by: Richard Levitte <levitte@openssl.org> (Merged from https://github.com/openssl/openssl/pull/9333)
75 lines
3.5 KiB
Plaintext
75 lines
3.5 KiB
Plaintext
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_local.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_local.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.
|