On Wed, Jan 18, 2012 at 9:19 AM, Jim Mlodgenski <jimm...@gmail.com> wrote:
> On Wed, Jan 18, 2012 at 3:08 AM, Heikki Linnakangas
> <heikki.linnakan...@enterprisedb.com> wrote:
>> On 18.01.2012 07:49, Fujii Masao wrote:
>>>
>>> On Fri, Jan 6, 2012 at 1:38 AM, Jim Mlodgenski<jimm...@gmail.com> wrote:
>>>>
>>>> I have a need to send banner messages to a psql client that I can set
>>>> on the server and will be displayed on any psql client that connects
>>>> to the database. This would be mostly used as an additional indicator
>>>> to which database you are connecting, but could also be used by people
>>>> to force their users to see an security message when connecting to the
>>>> database. The attached patch will allow you to execute
>>>>
>>>> ALTER DATABASE postgres SET
>>>>
>>>> client_message=E'********************************************************************************\nBEWARE:
>>>> You are connecting to a production database. If you do anything to\n
>>>> bring this server down, you will be destroyed by your supreme
>>>>
>>>> overlord.\n********************************************************************************\n';
>>>>
>>>> And then when you connect to psql, you will see:
>>>>
>>>> [e3@workstation bin]$ ./psql -U user1 postgres
>>>> psql (9.2devel)
>>>>
>>>> ********************************************************************************
>>>> BEWARE: You are connecting to a production database. If you do anything
>>>> to
>>>> bring this server down, you will be destroyed by your supreme
>>>> overlord.
>>>>
>>>> ********************************************************************************
>>>>
>>>> Type "help" for help.
>>>>
>>>> postgres=>
>>>>
>>>>
>>>> Any feedback is welcome.
>>>
>>>
>>> Adding new GUC parameter only for the purpose of warning psql users
>>> seems overkill to me. Basically we try to reduce the number of GUC
>>> parameters to make a configuration easier to a user, so I don't think that
>>> it's good idea to add new GUC for such a small benefit.
>>
>>
>> It seems quite useful to me...
>>
>>
>>> Instead, how
>>> about using .psqlrc file and writing a warning message in it by using
>>> \echo command?
>>
>>
>> That's not the same thing at all. Each client would need to put the warning
>> in that file, and you'd get it regardless of the database you connect to.
>>
>>
>>> Anyway, I found one problem in the patch. The patch defines client_message
>>> as PGC_USERSET parameter, which means that any psql can falsify a
>>> warning message, e.g., by setting the environment variable PGOPTIONS
>>> to "-c client_message=hoge". This seems to be something to avoid from
>>> security point of view.
>>
>>
>> I don't think that's a problem, it's just a free-form message to display.
>> But it also doesn't seem very useful to have it PGC_USERSET: if it's only
>> displayed at connect time, there's no point in changing it after connecting.
> Should we make it PGC_BACKEND?
>
>>
>> The only security problem that I can think of is a malicious server
>> (man-in-the-middle perhaps), that sends a banner that confuses
>>
>> Docs for PQparameterStatus() needs adjustment, now that client_message is
>> also one of the settings automatically reported to the client.
> I'll add the docs for that..
>
>>
>> The placement of the banner in psql looks currently like this:
>>
>>> $ psql postgres
>>>
>>> psql (9.2devel)
>>> Hello world!
>>> Type "help" for help.
>>
>>
>> or
>>
>>> postgres=# \c postgres
>>> Hello world!
>>> You are now connected to database "postgres" as user "heikki".
>>
>>
>> Are we happy with that? I think it would be better to print the banner just
>> before the prompt:
> I like that better. I'll make that change as well.
Here is the revised patch based on the feedback.
>
>>
>>> psql (9.2devel)
>>> Type "help" for help.
>>>
>>> Hello world!
>>>
>>> postgres=# \c postgres
>>> You are now connected to database "postgres" as user "heikki".
>>
>>> Hello world!
>>> postgres=#
>>
>> Should we prefix the banner with something that makes it clear that it's a
>> message coming from the server? Something like:
> I don't think the default prefix adds much for the user. If the
> administrator wants to let the user know that its from the server, he
> can add it to the message.
>
>>
>>> psql (9.2devel)
>>> Type "help" for help.
>>>
>>> Notice from server: Hello world!
>>>
>>> postgres=# \c postgres
>>> You are now connected to database "postgres" as user "heikki".
>>> Notice from server: Hello world!
>>> postgres=#
>>
>> --
>> Heikki Linnakangas
>> EnterpriseDB http://www.enterprisedb.com
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index e55b503..04bc671 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -5324,6 +5324,19 @@ dynamic_library_path = 'C:\tools\postgresql;H:\my_project\lib;$libdir'
</listitem>
</varlistentry>
+ <varlistentry id="guc-client-message" xreflabel="client_message">
+ <term><varname>client_message</varname> (<type>string</type>)</term>
+ <indexterm>
+ <primary><varname>client_message</> configuration parameter</primary>
+ </indexterm>
+ <listitem>
+ <para>
+ The <varname>client_message</varname> can be any string that will be
+ displayed to the user in the banner of psql.
+ </para>
+ </listitem>
+ </varlistentry>
+
</variablelist>
</sect2>
</sect1>
diff --git a/doc/src/sgml/libpq.sgml b/doc/src/sgml/libpq.sgml
index 72c9384..7dcb0bb 100644
--- a/doc/src/sgml/libpq.sgml
+++ b/doc/src/sgml/libpq.sgml
@@ -1487,6 +1487,7 @@ const char *PQparameterStatus(const PGconn *conn, const char *paramName);
<varname>server_encoding</>,
<varname>client_encoding</>,
<varname>application_name</>,
+ <varname>client_message</>,
<varname>is_superuser</>,
<varname>session_authorization</>,
<varname>DateStyle</>,
@@ -1499,7 +1500,8 @@ const char *PQparameterStatus(const PGconn *conn, const char *paramName);
<varname>standard_conforming_strings</> was not reported by releases
before 8.1;
<varname>IntervalStyle</> was not reported by releases before 8.4;
- <varname>application_name</> was not reported by releases before 9.0.)
+ <varname>application_name</> was not reported by releases before 9.0;
+ <varname>client_message</> was not reported by releases before 9.2.)
Note that
<varname>server_version</>,
<varname>server_encoding</> and
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 9fc96b2..39177cc 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -455,6 +455,7 @@ static char *log_destination_string;
static char *syslog_ident_str;
static bool phony_autocommit;
static bool session_auth_is_superuser;
+static char *client_message_string;
static double phony_random_seed;
static char *client_encoding_string;
static char *datestyle_string;
@@ -3018,6 +3019,17 @@ static struct config_string ConfigureNamesString[] =
check_application_name, assign_application_name, NULL
},
+ {
+ {"client_message", PGC_BACKEND, CLIENT_CONN_OTHER,
+ gettext_noop("Sets a message to be displayed to the user when connecting via psql."),
+ NULL,
+ GUC_REPORT | GUC_NO_SHOW_ALL
+ },
+ &client_message_string,
+ "",
+ NULL, NULL, NULL
+ },
+
/* End-of-list marker */
{
{NULL, 0, 0, NULL, NULL}, NULL, NULL, NULL, NULL, NULL
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 315db46..8eb5af5 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -515,6 +515,7 @@
#dynamic_library_path = '$libdir'
#local_preload_libraries = ''
+#client_message = ''
#------------------------------------------------------------------------------
diff --git a/src/bin/psql/command.c b/src/bin/psql/command.c
index 6c3f0aa..cd90a64 100644
--- a/src/bin/psql/command.c
+++ b/src/bin/psql/command.c
@@ -1653,6 +1653,8 @@ do_connect(char *dbname, char *user, char *host, char *port)
else
printf(_("You are now connected to database \"%s\" as user \"%s\".\n"),
PQdb(pset.db), PQuser(pset.db));
+
+ printClientMessage();
}
if (o_conn)
@@ -1707,6 +1709,23 @@ connection_warnings(bool in_startup)
/*
+ * printClientMessage
+ *
+ * Prints any message stored in the client_message GUC
+ */
+void
+printClientMessage(void)
+{
+ const char *message;
+
+ message = PQparameterStatus(pset.db, "client_message");
+
+ if (message)
+ printf(_("%s\n"), message);
+}
+
+
+/*
* printSSLInfo
*
* Prints information about the current SSL connection, if SSL is in use
diff --git a/src/bin/psql/command.h b/src/bin/psql/command.h
index f0bcea0..0e37386 100644
--- a/src/bin/psql/command.h
+++ b/src/bin/psql/command.h
@@ -36,6 +36,8 @@ extern bool do_pset(const char *param,
extern void connection_warnings(bool in_startup);
+extern void printClientMessage(void);
+
extern void SyncVariables(void);
extern void UnsyncVariables(void);
diff --git a/src/bin/psql/startup.c b/src/bin/psql/startup.c
index 8b1864c..b04daa1 100644
--- a/src/bin/psql/startup.c
+++ b/src/bin/psql/startup.c
@@ -302,7 +302,10 @@ main(int argc, char *argv[])
connection_warnings(true);
if (!pset.quiet && !pset.notty)
+ {
printf(_("Type \"help\" for help.\n\n"));
+ printClientMessage();
+ }
if (!pset.notty)
initializeInput(options.no_readline ? 0 : 1);
if (options.action_string) /* -f - was used */
--
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