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Add support for using SQL/MED compliant FOREIGN DATA WRAPPER, SERVER, 

and USER MAPPING as method to supply dblink connect parameters. Per
mailing list and PGCon discussions.
This commit is contained in:
Joe Conway 2009-06-06 21:27:56 +00:00
parent af98bb2ad7
commit 4334695b30
4 changed files with 228 additions and 5 deletions
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104
contrib/dblink/dblink.c
View File

@ -8,7 +8,7 @@
* Darko Prenosil <Darko.Prenosil@finteh.hr>
* Shridhar Daithankar <shridhar_daithankar@persistent.co.in>
*
* $PostgreSQL: pgsql/contrib/dblink/dblink.c,v 1.78 2009/06/02 03:21:56 joe Exp $
* $PostgreSQL: pgsql/contrib/dblink/dblink.c,v 1.79 2009/06/06 21:27:56 joe Exp $
* Copyright (c) 2001-2009, PostgreSQL Global Development Group
* ALL RIGHTS RESERVED;
*
@ -46,6 +46,7 @@
#include "catalog/pg_type.h"
#include "executor/executor.h"
#include "executor/spi.h"
#include "foreign/foreign.h"
#include "lib/stringinfo.h"
#include "miscadmin.h"
#include "nodes/execnodes.h"
@ -96,6 +97,8 @@ static char *generate_relation_name(Oid relid);
static void dblink_connstr_check(const char *connstr);
static void dblink_security_check(PGconn *conn, remoteConn *rconn);
static void dblink_res_error(const char *conname, PGresult *res, const char *dblink_context_msg, bool fail);
static char *get_connect_string(const char *servername);
static char *escape_param_str(const char *from);
/* Global */
static remoteConn *pconn = NULL;
@ -165,7 +168,11 @@ typedef struct remoteConnHashEnt
} \
else \
{ \
connstr = conname_or_str; \
connstr = get_connect_string(conname_or_str); \
if (connstr == NULL) \
{ \
connstr = conname_or_str; \
} \
dblink_connstr_check(connstr); \
conn = PQconnectdb(connstr); \
if (PQstatus(conn) == CONNECTION_BAD) \
@ -210,6 +217,7 @@ PG_FUNCTION_INFO_V1(dblink_connect);
Datum
dblink_connect(PG_FUNCTION_ARGS)
{
char *conname_or_str = NULL;
char *connstr = NULL;
char *connname = NULL;
char *msg;
@ -220,16 +228,21 @@ dblink_connect(PG_FUNCTION_ARGS)
if (PG_NARGS() == 2)
{
connstr = text_to_cstring(PG_GETARG_TEXT_PP(1));
conname_or_str = text_to_cstring(PG_GETARG_TEXT_PP(1));
connname = text_to_cstring(PG_GETARG_TEXT_PP(0));
}
else if (PG_NARGS() == 1)
connstr = text_to_cstring(PG_GETARG_TEXT_PP(0));
conname_or_str = text_to_cstring(PG_GETARG_TEXT_PP(0));
if (connname)
rconn = (remoteConn *) MemoryContextAlloc(TopMemoryContext,
sizeof(remoteConn));
/* first check for valid foreign data server */
connstr = get_connect_string(conname_or_str);
if (connstr == NULL)
connstr = conname_or_str;
/* check password in connection string if not superuser */
dblink_connstr_check(connstr);
conn = PQconnectdb(connstr);
@ -2353,3 +2366,86 @@ dblink_res_error(const char *conname, PGresult *res, const char *dblink_context_
errcontext("Error occurred on dblink connection named \"%s\": %s.",
dblink_context_conname, dblink_context_msg)));
}
/*
* Obtain connection string for a foreign server
*/
static char *
get_connect_string(const char *servername)
{
ForeignServer *foreign_server = NULL;
UserMapping *user_mapping;
ListCell *cell;
StringInfo buf = makeStringInfo();
ForeignDataWrapper *fdw;
AclResult aclresult;
/* first gather the server connstr options */
if (strlen(servername) < NAMEDATALEN)
foreign_server = GetForeignServerByName(servername, true);
if (foreign_server)
{
Oid serverid = foreign_server->serverid;
Oid fdwid = foreign_server->fdwid;
Oid userid = GetUserId();
user_mapping = GetUserMapping(userid, serverid);
fdw = GetForeignDataWrapper(fdwid);
/* Check permissions, user must have usage on the server. */
aclresult = pg_foreign_server_aclcheck(serverid, userid, ACL_USAGE);
if (aclresult != ACLCHECK_OK)
aclcheck_error(aclresult, ACL_KIND_FOREIGN_SERVER, foreign_server->servername);
foreach (cell, fdw->options)
{
DefElem *def = lfirst(cell);
appendStringInfo(buf, "%s='%s' ", def->defname,
escape_param_str(strVal(def->arg)));
}
foreach (cell, foreign_server->options)
{
DefElem *def = lfirst(cell);
appendStringInfo(buf, "%s='%s' ", def->defname,
escape_param_str(strVal(def->arg)));
}
foreach (cell, user_mapping->options)
{
DefElem *def = lfirst(cell);
appendStringInfo(buf, "%s='%s' ", def->defname,
escape_param_str(strVal(def->arg)));
}
return buf->data;
}
else
return NULL;
}
/*
* Escaping libpq connect parameter strings.
*
* Replaces "'" with "\'" and "\" with "\\".
*/
static char *
escape_param_str(const char *str)
{
const char *cp;
StringInfo buf = makeStringInfo();
for (cp = str; *cp; cp++)
{
if (*cp == '\\' || *cp == '\'')
appendStringInfoChar(buf, '\\');
appendStringInfoChar(buf, *cp);
}
return buf->data;
}

43
contrib/dblink/expected/dblink.out
View File

@ -784,3 +784,46 @@ SELECT dblink_disconnect('dtest1');
OK
(1 row)
-- test foreign data wrapper functionality
CREATE USER dblink_regression_test;
CREATE FOREIGN DATA WRAPPER postgresql;
CREATE SERVER fdtest FOREIGN DATA WRAPPER postgresql OPTIONS (dbname 'contrib_regression');
CREATE USER MAPPING FOR public SERVER fdtest;
GRANT USAGE ON FOREIGN SERVER fdtest TO dblink_regression_test;
GRANT EXECUTE ON FUNCTION dblink_connect_u(text, text) TO dblink_regression_test;
\set ORIGINAL_USER :USER
\c - dblink_regression_test
-- should fail
SELECT dblink_connect('myconn', 'fdtest');
ERROR: password is required
DETAIL: Non-superusers must provide a password in the connection string.
-- should succeed
SELECT dblink_connect_u('myconn', 'fdtest');
dblink_connect_u
------------------
OK
(1 row)
SELECT * FROM dblink('myconn','SELECT * FROM foo') AS t(a int, b text, c text[]);
a | b | c
----+---+---------------
0 | a | {a0,b0,c0}
1 | b | {a1,b1,c1}
2 | c | {a2,b2,c2}
3 | d | {a3,b3,c3}
4 | e | {a4,b4,c4}
5 | f | {a5,b5,c5}
6 | g | {a6,b6,c6}
7 | h | {a7,b7,c7}
8 | i | {a8,b8,c8}
9 | j | {a9,b9,c9}
10 | k | {a10,b10,c10}
(11 rows)
\c - :ORIGINAL_USER
REVOKE USAGE ON FOREIGN SERVER fdtest FROM dblink_regression_test;
REVOKE EXECUTE ON FUNCTION dblink_connect_u(text, text) FROM dblink_regression_test;
DROP USER dblink_regression_test;
DROP USER MAPPING FOR public SERVER fdtest;
DROP SERVER fdtest;
DROP FOREIGN DATA WRAPPER postgresql;

25
contrib/dblink/sql/dblink.sql
View File

@ -364,3 +364,28 @@ SELECT * from
SELECT dblink_cancel_query('dtest1');
SELECT dblink_error_message('dtest1');
SELECT dblink_disconnect('dtest1');
-- test foreign data wrapper functionality
CREATE USER dblink_regression_test;
CREATE FOREIGN DATA WRAPPER postgresql;
CREATE SERVER fdtest FOREIGN DATA WRAPPER postgresql OPTIONS (dbname 'contrib_regression');
CREATE USER MAPPING FOR public SERVER fdtest;
GRANT USAGE ON FOREIGN SERVER fdtest TO dblink_regression_test;
GRANT EXECUTE ON FUNCTION dblink_connect_u(text, text) TO dblink_regression_test;
\set ORIGINAL_USER :USER
\c - dblink_regression_test
-- should fail
SELECT dblink_connect('myconn', 'fdtest');
-- should succeed
SELECT dblink_connect_u('myconn', 'fdtest');
SELECT * FROM dblink('myconn','SELECT * FROM foo') AS t(a int, b text, c text[]);
\c - :ORIGINAL_USER
REVOKE USAGE ON FOREIGN SERVER fdtest FROM dblink_regression_test;
REVOKE EXECUTE ON FUNCTION dblink_connect_u(text, text) FROM dblink_regression_test;
DROP USER dblink_regression_test;
DROP USER MAPPING FOR public SERVER fdtest;
DROP SERVER fdtest;
DROP FOREIGN DATA WRAPPER postgresql;

61
doc/src/sgml/dblink.sgml
View File

@ -1,4 +1,4 @@
<!-- $PostgreSQL: pgsql/doc/src/sgml/dblink.sgml,v 1.6 2008/11/12 15:52:44 petere Exp $ -->
<!-- $PostgreSQL: pgsql/doc/src/sgml/dblink.sgml,v 1.7 2009/06/06 21:27:56 joe Exp $ -->
<sect1 id="dblink">
<title>dblink</title>
@ -42,6 +42,18 @@
only one unnamed connection is permitted at a time. The connection
will persist until closed or until the database session is ended.
</para>
<para>
The connection string may also be the name of an existing foreign
server that utilizes the postgresql_fdw foreign data wrapper library.
See the example below, as well as the following:
<simplelist type="inline">
<member><xref linkend="sql-createforeigndatawrapper" endterm="sql-createforeigndatawrapper-title"></member>
<member><xref linkend="sql-createserver" endterm="sql-createserver-title"></member>
<member><xref linkend="sql-createusermapping" endterm="sql-createusermapping-title"></member>
</simplelist>
</para>
</refsect1>
<refsect1>
@ -113,6 +125,53 @@
----------------
OK
(1 row)
-- FOREIGN DATA WRAPPER functionality
-- Note: local connection must require password authentication for this to work properly
-- Otherwise, you will receive the following error from dblink_connect():
-- ----------------------------------------------------------------------
-- ERROR: password is required
-- DETAIL: Non-superuser cannot connect if the server does not request a password.
-- HINT: Target server's authentication method must be changed.
CREATE USER dblink_regression_test WITH PASSWORD 'secret';
CREATE FOREIGN DATA WRAPPER postgresql;
CREATE SERVER fdtest FOREIGN DATA WRAPPER postgresql OPTIONS (hostaddr '127.0.0.1', dbname 'contrib_regression');
CREATE USER MAPPING FOR dblink_regression_test SERVER fdtest OPTIONS (user 'dblink_regression_test', password 'secret');
GRANT USAGE ON FOREIGN SERVER fdtest TO dblink_regression_test;
GRANT SELECT ON TABLE foo TO dblink_regression_test;
\set ORIGINAL_USER :USER
\c - dblink_regression_test
SELECT dblink_connect('myconn', 'fdtest');
dblink_connect
----------------
OK
(1 row)
SELECT * FROM dblink('myconn','SELECT * FROM foo') AS t(a int, b text, c text[]);
a | b | c
----+---+---------------
0 | a | {a0,b0,c0}
1 | b | {a1,b1,c1}
2 | c | {a2,b2,c2}
3 | d | {a3,b3,c3}
4 | e | {a4,b4,c4}
5 | f | {a5,b5,c5}
6 | g | {a6,b6,c6}
7 | h | {a7,b7,c7}
8 | i | {a8,b8,c8}
9 | j | {a9,b9,c9}
10 | k | {a10,b10,c10}
(11 rows)
\c - :ORIGINAL_USER
REVOKE USAGE ON FOREIGN SERVER fdtest FROM dblink_regression_test;
REVOKE SELECT ON TABLE foo FROM dblink_regression_test;
DROP USER MAPPING FOR dblink_regression_test SERVER fdtest;
DROP USER dblink_regression_test;
DROP SERVER fdtest;
DROP FOREIGN DATA WRAPPER postgresql;
</programlisting>
</refsect1>
</refentry>