Re: New functions in sslinfo module

On 04/21/2014 07:51 AM, Воронин Дмитрий wrote:
> I put patch generated on git diffs to this letter. I make an a thread in
> postgresql commit fest:
> https://commitfest.postgresql.org/action/patch_view?id=1438

Thanks for the patch, it seems like a useful feature.

=== General ===

- Applies cleanly to HEAD and compiles without warnings.

- The test suite passes.

- x509v3 support was added in OpenSSL 0.9.2 and sslinfo already depends
heavily on OpenSSL so no new dependencies.

=== User functionality ===

- If you are a user of the sslinfo extension the new functions should be
useful additions.

- I tested the code without SSL, with certificate but without client
certificate, with client certificates first without extensions and the
with. All of this worked fine except for some usability which could be
improved, see below.

- I cannot see the use for ssl_get_count_of_extensions(). When would
anyone need to know the number of extensions? I think this is an
implementation detail of OpenSSL which we do not need to expose. If any
user wants this feature he can count the extension names.

- Documentation is missing for the new functions.

- I think the names of the new functions should be change. Below are my
suggestions. Other suggestions are welcome.

* ssl_extension_value(text)
* ssl_extension_is_critical()
* ssl_extension_names()
* ssl_extension_count() (If we should keep it.)

- Would it be interesting to have a set returning function which returns
all extensions with both the names and the values? Like the below.

$ SELECT * FROM ssl_extensions();
name | value
------------------+------------------------------------------------------
basicConstraints | CA:FALSE
keyUsage | Digital Signature, Non Repudiation, Key Encipherment
(2 rows)

- I do not think that ssl_get_extension_names() should return a single
row with NULL when the certificate has no extensions or when there is no
certificate at all. Returning zero rows in this case should make it
easier to use.

- Currently ssl_is_critical_extension() and ssl_get_extension_value()
throw an error when the requested extension is not in the certificate.

I am not sure if I like this behavior. I think I would prefer if the
code always throws an error when name lookup fails, and never when it is
successful. For a valid extension name I think NULL should be returned
when it does not exist.

=== Code review: main ===

- Why are X509_NAME_field_to_text(), X509_NAME_to_text(),
ASN1_STRING_to_text() and get_extension() not static? None of these are
a symbol which should be exported.

- I have not worked with extension myself, but since your change adds
functions to the extension I think you need to create a version 1.1
instead of modifying 1.0 in place. If so you also need to write an
upgrade script from 1.0 to 1.1. See dblink--1.0--1.1.sql for an example.

- Please break out the comment fix for ssl_cipher() into a separate patch.

- Why do you use pg_do_encoding_conversion() over pg_any_to_server()?
pg_any_to_server() is implemented using pg_do_encoding_conversion().

- I think you should use OBJ_txt2nid() rather than OBJ_sn2nid() +
OBJ_ln2nid(). You should probably also use OBJ_txt2obj() since
X509_get_ext_by_NID() will call OBJ_nid2obj() anyway.

- You should free the extension_name string. I do not think it is ok to
leak it to the end of the query.

- I think you need to convert the extension values and names to the
server encoding. I just wonder if we need to support data which is
incorrectly encoded.

=== Code review: style issues ===

- Trailing whitespace in sslinfo--1.0.sql and sslinfo.c.q

- sslinfo--1.0.sql does not end in a newline.

- I do not think the PostgreSQL project adds authors in the top comment
of files in cases like this. Authors get credit in the commit messages.

- I think you can remove the prototypes of all the ssl_* functions.

- Adding the have in "Indicates whether current client have provided a
certificate" is not necessary. The previous wording looks correct to my
non-native speaker eyes.

- Too much white space in variable declarations in get_extension().

- Extra space before -1 in "X509_get_ext_by_NID(certificate,
extension_nid, -1);"

- Please do not initialize variables unless necessary. Compilers are
pretty good at warning about uninitialized usage. For example both
locate and extension_nid do not need to be initialized.

- Remove empty line directly before ssl_get_extension_value().

- Try to follow variable naming conventions from other functions (e.g.
use nid rather than extension_nid, membuf rather than bio, sp rather
than value).

- I am pretty sure the variable you call locate should be called
location (or loc for short).

- There should not be any spaces around "->".

- The declaration of *extension in ssl_get_extension_value is not
aligned properly.

- Remove white space in variable declaration in
ssl_get_count_of_extensions().

- Incorrectly alignment of variable declarations in
ssl_get_extension_names().

- All the "Returns X datum" comments look redundant to me, but this is a
matter of preference.

- The star when declaring result in ssl_get_extension_names() should be
put on the other side of the white space.

--
Andreas Karlsson