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Add test for early backend startup errors
The new test tests the libpq fallback behavior on an early error, which was fixed in the previous commit. This adds an IS_INJECTION_POINT_ATTACHED() macro, to allow writing injected test code alongside the normal source code. In principle, the new test could've been implemented by an extra test module with a callback that sets the FrontendProtocol global variable, but I think it's more clear to have the test code right where the injection point is, because it has pretty intimate knowledge of the surrounding context it runs in. Reviewed-by: Michael Paquier Discussion: https://www.postgresql.org/message-id/CAOYmi%2Bnwvu21mJ4DYKUa98HdfM_KZJi7B1MhyXtnsyOO-PB6Ww%40mail.gmail.com
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‎doc/src/sgml/xfunc.sgml

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@@ -3672,6 +3672,31 @@ custom_injection_callback(const char *name, const void *private_data)
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logic.
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</para>
36743674

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<para>
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An alternative way to define the action to take when an injection point
3677+
is reached is to add the testing code alongside the normal source
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code. This can be useful if the action e.g. depends on local variables
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that are not accessible to loaded modules. The
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<function>IS_INJECTION_POINT_ATTACHED</function> macro can then be used
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to check if an injection point is attached, for example:
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<programlisting>
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#ifdef USE_INJECTION_POINTS
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if (IS_INJECTION_POINT_ATTACHED("before-foobar"))
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{
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/* change a local variable if injection point is attached */
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local_var = 123;
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3689+
/* also execute the callback */
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INJECTION_POINT_CACHED("before-foobar");
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}
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#endif
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</programlisting>
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Note that the callback attached to the injection point will not be
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executed by the <function>IS_INJECTION_POINT_ATTACHED</function>
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macro. If you want to execute the callback, you must also call
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<function>INJECTION_POINT_CACHED</function> like in the above example.
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</para>
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<para>
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Optionally, it is possible to detach an injection point by calling:
36773702
<programlisting>

‎src/backend/tcop/backend_startup.c

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@@ -33,6 +33,7 @@
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#include "tcop/backend_startup.h"
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#include "tcop/tcopprot.h"
3535
#include "utils/builtins.h"
36+
#include "utils/injection_point.h"
3637
#include "utils/memutils.h"
3738
#include "utils/ps_status.h"
3839
#include "utils/timeout.h"
@@ -213,6 +214,21 @@ BackendInitialize(ClientSocket *client_sock, CAC_state cac)
213214
remote_host)));
214215
}
215216

217+
/* For testing client error handling */
218+
#ifdef USE_INJECTION_POINTS
219+
INJECTION_POINT("backend-initialize");
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if (IS_INJECTION_POINT_ATTACHED("backend-initialize-v2-error"))
221+
{
222+
/*
223+
* This simulates an early error from a pre-v14 server, which used the
224+
* version 2 protocol for any errors that occurred before processing
225+
* the startup packet.
226+
*/
227+
FrontendProtocol = PG_PROTOCOL(2, 0);
228+
elog(FATAL, "protocol version 2 error triggered");
229+
}
230+
#endif
231+
216232
/*
217233
* If we did a reverse lookup to name, we might as well save the results
218234
* rather than possibly repeating the lookup during authentication.

‎src/backend/utils/misc/injection_point.c

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Original file line numberDiff line numberDiff line change
@@ -570,3 +570,17 @@ InjectionPointCached(const char *name)
570570
elog(ERROR, "Injection points are not supported by this build");
571571
#endif
572572
}
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574+
/*
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* Test if an injection point is defined.
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*/
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bool
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IsInjectionPointAttached(const char *name)
579+
{
580+
#ifdef USE_INJECTION_POINTS
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return InjectionPointCacheRefresh(name) != NULL;
582+
#else
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elog(ERROR, "Injection points are not supported by this build");
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return false; /* silence compiler */
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#endif
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}

‎src/include/utils/injection_point.h

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Original file line numberDiff line numberDiff line change
@@ -18,10 +18,12 @@
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#define INJECTION_POINT_LOAD(name) InjectionPointLoad(name)
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#define INJECTION_POINT(name) InjectionPointRun(name)
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#define INJECTION_POINT_CACHED(name) InjectionPointCached(name)
21+
#define IS_INJECTION_POINT_ATTACHED(name) IsInjectionPointAttached(name)
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#else
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#define INJECTION_POINT_LOAD(name) ((void) name)
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#define INJECTION_POINT(name) ((void) name)
2425
#define INJECTION_POINT_CACHED(name) ((void) name)
26+
#define IS_INJECTION_POINT_ATTACHED(name) (false)
2527
#endif
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2729
/*
@@ -41,6 +43,7 @@ extern void InjectionPointAttach(const char *name,
4143
extern void InjectionPointLoad(const char *name);
4244
extern void InjectionPointRun(const char *name);
4345
extern void InjectionPointCached(const char *name);
46+
extern bool IsInjectionPointAttached(const char *name);
4447
extern bool InjectionPointDetach(const char *name);
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4649
#ifdef EXEC_BACKEND

‎src/interfaces/libpq/Makefile

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Original file line numberDiff line numberDiff line change
@@ -9,11 +9,13 @@
99
#
1010
#-------------------------------------------------------------------------
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EXTRA_INSTALL=src/test/modules/injection_points
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1214
subdir = src/interfaces/libpq
1315
top_builddir = ../../..
1416
include $(top_builddir)/src/Makefile.global
1517

16-
export with_ssl with_gssapi with_krb_srvnam
18+
export with_ssl with_gssapi with_krb_srvnam enable_injection_points
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PGFILEDESC = "PostgreSQL Access Library"
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‎src/interfaces/libpq/meson.build

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@@ -121,6 +121,7 @@ tests += {
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't/005_negotiate_encryption.pl',
122122
],
123123
'env': {
124+
'enable_injection_points': get_option('injection_points') ? 'yes' : 'no',
124125
'with_ssl': ssl_library,
125126
'with_gssapi': gssapi.found() ? 'yes' : 'no',
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'with_krb_srvnam': 'postgres',

‎src/interfaces/libpq/t/005_negotiate_encryption.pl

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@@ -90,6 +90,8 @@
9090
$ENV{PG_TEST_EXTRA} && $ENV{PG_TEST_EXTRA} =~ /\bkerberos\b/;
9191
my $ssl_supported = $ENV{with_ssl} eq 'openssl';
9292

93+
my $injection_points_supported = $ENV{enable_injection_points} eq 'yes';
94+
9395
###
9496
### Prepare test server for GSSAPI and SSL authentication, with a few
9597
### different test users and helper functions. We don't actually
@@ -155,6 +157,10 @@
155157
$node->safe_psql('postgres', 'CREATE USER nossluser;');
156158
$node->safe_psql('postgres', 'CREATE USER gssuser;');
157159
$node->safe_psql('postgres', 'CREATE USER nogssuser;');
160+
if ($injection_points_supported != 0)
161+
{
162+
$node->safe_psql('postgres', 'CREATE EXTENSION injection_points;');
163+
}
158164

159165
my $unixdir = $node->safe_psql('postgres', 'SHOW unix_socket_directories;');
160166
chomp($unixdir);
@@ -312,6 +318,29 @@ BEGIN
312318
['disable'], \@all_sslmodes, \@all_sslnegotiations,
313319
parse_table($test_table));
314320

321+
if ($injection_points_supported != 0)
322+
{
323+
$node->safe_psql(
324+
'postgres',
325+
"SELECT injection_points_attach('backend-initialize', 'error');",
326+
connstr => "user=localuser host=$unixdir");
327+
connect_test(
328+
$node,
329+
"user=testuser sslmode=prefer",
330+
'connect, backenderror -> fail');
331+
$node->restart;
332+
333+
$node->safe_psql(
334+
'postgres',
335+
"SELECT injection_points_attach('backend-initialize-v2-error', 'error');",
336+
connstr => "user=localuser host=$unixdir");
337+
connect_test(
338+
$node,
339+
"user=testuser sslmode=prefer",
340+
'connect, v2error -> fail');
341+
$node->restart;
342+
}
343+
315344
# Disable SSL again
316345
$node->adjust_conf('postgresql.conf', 'ssl', 'off');
317346
$node->reload;
@@ -393,6 +422,29 @@ BEGIN
393422
test_matrix($node, [ 'testuser', 'gssuser', 'nogssuser' ],
394423
\@all_gssencmodes, $sslmodes, $sslnegotiations,
395424
parse_table($test_table));
425+
426+
if ($injection_points_supported != 0)
427+
{
428+
$node->safe_psql(
429+
'postgres',
430+
"SELECT injection_points_attach('backend-initialize', 'error');",
431+
connstr => "user=localuser host=$unixdir");
432+
connect_test(
433+
$node,
434+
"user=testuser gssencmode=prefer sslmode=disable",
435+
'connect, backenderror, reconnect, backenderror -> fail');
436+
$node->restart;
437+
438+
$node->safe_psql(
439+
'postgres',
440+
"SELECT injection_points_attach('backend-initialize-v2-error', 'error');",
441+
connstr => "user=localuser host=$unixdir");
442+
connect_test(
443+
$node,
444+
"user=testuser gssencmode=prefer sslmode=disable",
445+
'connect, v2error -> fail');
446+
$node->restart;
447+
}
396448
}
397449

398450
###
@@ -738,6 +790,10 @@ sub parse_log_events
738790
push @events, "gssreject" if $line =~ /GSSENCRequest rejected/;
739791
push @events, "authfail" if $line =~ /no pg_hba.conf entry/;
740792
push @events, "authok" if $line =~ /connection authenticated/;
793+
push @events, "backenderror"
794+
if $line =~ /error triggered for injection point backend-/;
795+
push @events, "v2error"
796+
if $line =~ /protocol version 2 error triggered/;
741797
}
742798

743799
# No events at all is represented by "-"

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