postgresql

History

Andres Freund 4f85fde8eb Introduce and use infrastructure for interrupt processing during client reads. Up to now large swathes of backend code ran inside signal handlers while reading commands from the client, to allow for speedy reaction to asynchronous events. Most prominently shared invalidation and NOTIFY handling. That means that complex code like the starting/stopping of transactions is run in signal handlers... The required code was fragile and verbose, and is likely to contain bugs. That approach also severely limited what could be done while communicating with the client. As the read might be from within openssl it wasn't safely possible to trigger an error, e.g. to cancel a backend in idle-in-transaction state. We did that in some cases, namely fatal errors, nonetheless. Now that FE/BE communication in the backend employs non-blocking sockets and latches to block, we can quite simply interrupt reads from signal handlers by setting the latch. That allows us to signal an interrupted read, which is supposed to be retried after returning from within the ssl library. As signal handlers now only need to set the latch to guarantee timely interrupt processing, remove a fair amount of complicated & fragile code from async.c and sinval.c. We could now actually start to process some kinds of interrupts, like sinval ones, more often that before, but that seems better done separately. This work will hopefully allow to handle cases like being blocked by sending data, interrupting idle transactions and similar to be implemented without too much effort. In addition to allowing getting rid of ImmediateInterruptOK, that is. Author: Andres Freund Reviewed-By: Heikki Linnakangas		2015-02-03 22:25:20 +01:00
..
Makefile	Support frontend-backend protocol communication using a shm_mq.	2014-10-31 12:02:40 -04:00
README.SSL	Remove useless whitespace at end of lines	2010-11-23 22:34:55 +02:00
auth.c	Be more careful to not lose sync in the FE/BE protocol.	2015-02-02 17:09:53 +02:00
be-fsstubs.c	Update copyright for 2015	2015-01-06 11:43:47 -05:00
be-secure-openssl.c	Introduce and use infrastructure for interrupt processing during client reads.	2015-02-03 22:25:20 +01:00
be-secure.c	Introduce and use infrastructure for interrupt processing during client reads.	2015-02-03 22:25:20 +01:00
crypt.c	Update copyright for 2015	2015-01-06 11:43:47 -05:00
hba.c	Replace a bunch more uses of strncpy() with safer coding.	2015-01-24 13:05:42 -05:00
ip.c	Update copyright for 2015	2015-01-06 11:43:47 -05:00
md5.c	Update copyright for 2015	2015-01-06 11:43:47 -05:00
pg_hba.conf.sample	Remove support for native krb5 authentication	2014-01-19 17:05:01 +01:00
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	Use a nonblocking socket for FE/BE communication and block using latches.	2015-02-03 22:03:48 +01:00
pqformat.c	Update copyright for 2015	2015-01-06 11:43:47 -05:00
pqmq.c	Update copyright for 2015	2015-01-06 11:43:47 -05:00
pqsignal.c	Update copyright for 2015	2015-01-06 11:43:47 -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

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