postgresql/src/backend/libpq
Tom Lane 0a20ff54f5 Split up guc.c for better build speed and ease of maintenance.
guc.c has grown to be one of our largest .c files, making it
a bottleneck for compilation.  It's also acquired a bunch of
knowledge that'd be better kept elsewhere, because of our not
very good habit of putting variable-specific check hooks here.
Hence, split it up along these lines:

* guc.c itself retains just the core GUC housekeeping mechanisms.
* New file guc_funcs.c contains the SET/SHOW interfaces and some
  SQL-accessible functions for GUC manipulation.
* New file guc_tables.c contains the data arrays that define the
  built-in GUC variables, along with some already-exported constant
  tables.
* GUC check/assign/show hook functions are moved to the variable's
  home module, whenever that's clearly identifiable.  A few hard-
  to-classify hooks ended up in commands/variable.c, which was
  already a home for miscellaneous GUC hook functions.

To avoid cluttering a lot more header files with #include "guc.h",
I also invented a new header file utils/guc_hooks.h and put all
the GUC hook functions' declarations there, regardless of their
originating module.  That allowed removal of #include "guc.h"
from some existing headers.  The fallout from that (hopefully
all caught here) demonstrates clearly why such inclusions are
best minimized: there are a lot of files that, for example,
were getting array.h at two or more levels of remove, despite
not having any connection at all to GUCs in themselves.

There is some very minor code beautification here, such as
renaming a couple of inconsistently-named hook functions
and improving some comments.  But mostly this just moves
code from point A to point B and deals with the ensuing
needs for #include adjustments and exporting a few functions
that previously weren't exported.

Patch by me, per a suggestion from Andres Freund; thanks also
to Michael Paquier for the idea to invent guc_funcs.c.

Discussion: https://postgr.es/m/587607.1662836699@sss.pgh.pa.us
2022-09-13 11:11:45 -04:00
..
Makefile Refactor SASL code with a generic interface for its mechanisms 2021-07-07 10:55:15 +09:00
README.SSL Move EDH support to common files 2018-01-23 07:11:38 -05:00
auth-sasl.c Improve error handling of cryptohash computations 2022-01-11 09:55:16 +09:00
auth-scram.c Improve error handling of HMAC computations 2022-01-13 16:17:21 +09:00
auth.c Replace loading of ldap_start_tls_sA() by direct function call 2022-09-12 09:07:10 +09:00
be-fsstubs.c Prevent write operations on large objects in read-only transactions 2022-07-04 15:48:52 +09:00
be-gssapi-common.c Update copyright for 2022 2022-01-07 19:04:57 -05:00
be-secure-common.c Remove misguided SSL key file ownership check in libpq. 2022-05-26 14:14:05 -04:00
be-secure-gssapi.c Update copyright for 2022 2022-01-07 19:04:57 -05:00
be-secure-openssl.c Don't reflect unescaped cert data to the logs 2022-09-13 16:10:50 +02:00
be-secure.c Remove configure probe for netinet/tcp.h. 2022-08-18 16:31:11 +12:00
crypt.c Improve error handling of cryptohash computations 2022-01-11 09:55:16 +09:00
hba.c Fix an assortment of improper usages of string functions 2022-09-06 13:19:44 +12:00
ifaddr.c Remove configure probe for sockaddr_in6 and require AF_INET6. 2022-08-26 10:18:30 +12:00
pg_hba.conf.sample pg_hba.conf.sample: Reword connection type section 2021-04-29 07:00:20 +02:00
pg_ident.conf.sample Reformat the comments in pg_hba.conf and pg_ident.conf 2010-01-26 06:58:39 +00:00
pqcomm.c Split up guc.c for better build speed and ease of maintenance. 2022-09-13 11:11:45 -04:00
pqformat.c Update copyright for 2022 2022-01-07 19:04:57 -05:00
pqmq.c Update copyright for 2022 2022-01-07 19:04:57 -05:00
pqsignal.c Update copyright for 2022 2022-01-07 19:04:57 -05:00

README.SSL

src/backend/libpq/README.SSL

SSL
===

>From the servers perspective:


  Receives StartupPacket
           |
           |
 (Is SSL_NEGOTIATE_CODE?) -----------  Normal startup
           |                  No
           |
           | Yes
           |
           |
 (Server compiled with USE_SSL?) ------- Send 'N'
           |                       No        |
           |                                 |
           | Yes                         Normal startup
           |
           |
        Send 'S'
           |
           |
      Establish SSL
           |
           |
      Normal startup





>From the clients perspective (v6.6 client _with_ SSL):


      Connect
         |
         |
  Send packet with SSL_NEGOTIATE_CODE
         |
         |
  Receive single char  ------- 'S' -------- Establish SSL
         |                                       |
         | '<else>'                              |
         |                                  Normal startup
         |
         |
   Is it 'E' for error  ------------------- Retry connection
         |                  Yes             without SSL
         | No
         |
   Is it 'N' for normal ------------------- Normal startup
         |                  Yes
         |
   Fail with unknown

---------------------------------------------------------------------------

Ephemeral DH
============

Since the server static private key ($DataDir/server.key) will
normally be stored unencrypted so that the database backend can
restart automatically, it is important that we select an algorithm
that continues to provide confidentiality even if the attacker has the
server's private key.  Ephemeral DH (EDH) keys provide this and more
(Perfect Forward Secrecy aka PFS).

N.B., the static private key should still be protected to the largest
extent possible, to minimize the risk of impersonations.

Another benefit of EDH is that it allows the backend and clients to
use DSA keys.  DSA keys can only provide digital signatures, not
encryption, and are often acceptable in jurisdictions where RSA keys
are unacceptable.

The downside to EDH is that it makes it impossible to use ssldump(1)
if there's a problem establishing an SSL session.  In this case you'll
need to temporarily disable EDH (see initialize_dh()).