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Fix error handling in libpqrcv_connect()

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When libpqrcv_connect (also known as walrcv_connect()) failed, it leaked the
libpq connection. In most paths that's fairly harmless, as the calling process
will exit soon after. But e.g. CREATE SUBSCRIPTION could lead to a somewhat
longer lived leak.

Fix by releasing resources, including the libpq connection, on error.

Add a test exercising the error code path. To make it reliable and safe, the
test tries to connect to port=-1, which happens to fail during connection
establishment, rather than during connection string parsing.

Reviewed-by: Noah Misch <noah@leadboat.com>
Discussion: https://postgr.es/m/20230121011237.q52apbvlarfv6jm6@awork3.anarazel.de
Backpatch: 11-
This commit is contained in:
Andres Freund 2023-01-23 18:04:02 -08:00
parent 72d611109e
commit c5864805ba
3 changed files with 32 additions and 13 deletions
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26
src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
View File

@ -164,10 +164,7 @@ libpqrcv_connect(const char *conninfo, bool logical, const char *appname,
conn->streamConn = PQconnectStartParams(keys, vals,
/* expand_dbname = */ true);
if (PQstatus(conn->streamConn) == CONNECTION_BAD)
{
*err = pchomp(PQerrorMessage(conn->streamConn));
return NULL;
}
goto bad_connection_errmsg;
/*
* Poll connection until we have OK or FAILED status.
@ -209,10 +206,7 @@ libpqrcv_connect(const char *conninfo, bool logical, const char *appname,
} while (status != PGRES_POLLING_OK && status != PGRES_POLLING_FAILED);
if (PQstatus(conn->streamConn) != CONNECTION_OK)
{
*err = pchomp(PQerrorMessage(conn->streamConn));
return NULL;
}
goto bad_connection_errmsg;
if (logical)
{
@ -223,9 +217,9 @@ libpqrcv_connect(const char *conninfo, bool logical, const char *appname,
if (PQresultStatus(res) != PGRES_TUPLES_OK)
{
PQclear(res);
ereport(ERROR,
(errmsg("could not clear search path: %s",
pchomp(PQerrorMessage(conn->streamConn)))));
*err = psprintf(_("could not clear search path: %s"),
pchomp(PQerrorMessage(conn->streamConn)));
goto bad_connection;
}
PQclear(res);
}
@ -233,6 +227,16 @@ libpqrcv_connect(const char *conninfo, bool logical, const char *appname,
conn->logical = logical;
return conn;
/* error path, using libpq's error message */
bad_connection_errmsg:
*err = pchomp(PQerrorMessage(conn->streamConn));
/* error path, error already set */
bad_connection:
PQfinish(conn->streamConn);
pfree(conn);
return NULL;
}
/*

10
src/test/regress/expected/subscription.out
View File

@ -71,7 +71,15 @@ ERROR: cannot enable subscription that does not have a slot name
ALTER SUBSCRIPTION regress_testsub3 REFRESH PUBLICATION;
ERROR: ALTER SUBSCRIPTION ... REFRESH is not allowed for disabled subscriptions
DROP SUBSCRIPTION regress_testsub3;
-- fail - invalid connection string
-- fail, connection string does not parse
CREATE SUBSCRIPTION regress_testsub5 CONNECTION 'i_dont_exist=param' PUBLICATION testpub;
ERROR: invalid connection string syntax: invalid connection option "i_dont_exist"
-- fail, connection string parses, but doesn't work (and does so without
-- connecting, so this is reliable and safe)
CREATE SUBSCRIPTION regress_testsub5 CONNECTION 'port=-1' PUBLICATION testpub;
ERROR: could not connect to the publisher: invalid port number: "-1"
-- fail - invalid connection string during ALTER
ALTER SUBSCRIPTION regress_testsub CONNECTION 'foobar';
ERROR: invalid connection string syntax: missing "=" after "foobar" in connection info string

9
src/test/regress/sql/subscription.sql
View File

@ -56,7 +56,14 @@ ALTER SUBSCRIPTION regress_testsub3 REFRESH PUBLICATION;
DROP SUBSCRIPTION regress_testsub3;
-- fail - invalid connection string
-- fail, connection string does not parse
CREATE SUBSCRIPTION regress_testsub5 CONNECTION 'i_dont_exist=param' PUBLICATION testpub;
-- fail, connection string parses, but doesn't work (and does so without
-- connecting, so this is reliable and safe)
CREATE SUBSCRIPTION regress_testsub5 CONNECTION 'port=-1' PUBLICATION testpub;
-- fail - invalid connection string during ALTER
ALTER SUBSCRIPTION regress_testsub CONNECTION 'foobar';
\dRs+