Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * connection.c
4 : * Connection management functions for postgres_fdw
5 : *
6 : * Portions Copyright (c) 2012-2026, PostgreSQL Global Development Group
7 : *
8 : * IDENTIFICATION
9 : * contrib/postgres_fdw/connection.c
10 : *
11 : *-------------------------------------------------------------------------
12 : */
13 : #include "postgres.h"
14 :
15 : #if HAVE_POLL_H
16 : #include <poll.h>
17 : #endif
18 :
19 : #include "access/htup_details.h"
20 : #include "access/xact.h"
21 : #include "catalog/pg_user_mapping.h"
22 : #include "commands/defrem.h"
23 : #include "common/base64.h"
24 : #include "funcapi.h"
25 : #include "libpq/libpq-be.h"
26 : #include "libpq/libpq-be-fe-helpers.h"
27 : #include "mb/pg_wchar.h"
28 : #include "miscadmin.h"
29 : #include "pgstat.h"
30 : #include "postgres_fdw.h"
31 : #include "storage/latch.h"
32 : #include "utils/builtins.h"
33 : #include "utils/hsearch.h"
34 : #include "utils/inval.h"
35 : #include "utils/syscache.h"
36 : #include "utils/tuplestore.h"
37 :
38 : /*
39 : * Connection cache hash table entry
40 : *
41 : * The lookup key in this hash table is the user mapping OID. We use just one
42 : * connection per user mapping ID, which ensures that all the scans use the
43 : * same snapshot during a query. Using the user mapping OID rather than
44 : * the foreign server OID + user OID avoids creating multiple connections when
45 : * the public user mapping applies to all user OIDs.
46 : *
47 : * The "conn" pointer can be NULL if we don't currently have a live connection.
48 : * When we do have a connection, xact_depth tracks the current depth of
49 : * transactions and subtransactions open on the remote side. We need to issue
50 : * commands at the same nesting depth on the remote as we're executing at
51 : * ourselves, so that rolling back a subtransaction will kill the right
52 : * queries and not the wrong ones.
53 : */
54 : typedef Oid ConnCacheKey;
55 :
56 : typedef struct ConnCacheEntry
57 : {
58 : ConnCacheKey key; /* hash key (must be first) */
59 : PGconn *conn; /* connection to foreign server, or NULL */
60 : /* Remaining fields are invalid when conn is NULL: */
61 : int xact_depth; /* 0 = no xact open, 1 = main xact open, 2 =
62 : * one level of subxact open, etc */
63 : bool xact_read_only; /* xact r/o state */
64 : bool have_prep_stmt; /* have we prepared any stmts in this xact? */
65 : bool have_error; /* have any subxacts aborted in this xact? */
66 : bool changing_xact_state; /* xact state change in process */
67 : bool parallel_commit; /* do we commit (sub)xacts in parallel? */
68 : bool parallel_abort; /* do we abort (sub)xacts in parallel? */
69 : bool invalidated; /* true if reconnect is pending */
70 : bool keep_connections; /* setting value of keep_connections
71 : * server option */
72 : Oid serverid; /* foreign server OID used to get server name */
73 : uint32 server_hashvalue; /* hash value of foreign server OID */
74 : uint32 mapping_hashvalue; /* hash value of user mapping OID */
75 : PgFdwConnState state; /* extra per-connection state */
76 : } ConnCacheEntry;
77 :
78 : /*
79 : * Connection cache (initialized on first use)
80 : */
81 : static HTAB *ConnectionHash = NULL;
82 :
83 : /* for assigning cursor numbers and prepared statement numbers */
84 : static unsigned int cursor_number = 0;
85 : static unsigned int prep_stmt_number = 0;
86 :
87 : /* tracks whether any work is needed in callback functions */
88 : static bool xact_got_connection = false;
89 :
90 : /*
91 : * tracks the topmost read-only local transaction's nesting level determined
92 : * by GetTopReadOnlyTransactionNestLevel()
93 : */
94 : static int read_only_level = 0;
95 :
96 : /* custom wait event values, retrieved from shared memory */
97 : static uint32 pgfdw_we_cleanup_result = 0;
98 : static uint32 pgfdw_we_connect = 0;
99 : static uint32 pgfdw_we_get_result = 0;
100 :
101 : /*
102 : * Milliseconds to wait to cancel an in-progress query or execute a cleanup
103 : * query; if it takes longer than 30 seconds to do these, we assume the
104 : * connection is dead.
105 : */
106 : #define CONNECTION_CLEANUP_TIMEOUT 30000
107 :
108 : /*
109 : * Milliseconds to wait before issuing another cancel request. This covers
110 : * the race condition where the remote session ignored our cancel request
111 : * because it arrived while idle.
112 : */
113 : #define RETRY_CANCEL_TIMEOUT 1000
114 :
115 : /* Macro for constructing abort command to be sent */
116 : #define CONSTRUCT_ABORT_COMMAND(sql, entry, toplevel) \
117 : do { \
118 : if (toplevel) \
119 : snprintf((sql), sizeof(sql), \
120 : "ABORT TRANSACTION"); \
121 : else \
122 : snprintf((sql), sizeof(sql), \
123 : "ROLLBACK TO SAVEPOINT s%d; RELEASE SAVEPOINT s%d", \
124 : (entry)->xact_depth, (entry)->xact_depth); \
125 : } while(0)
126 :
127 : /*
128 : * Extension version number, for supporting older extension versions' objects
129 : */
130 : enum pgfdwVersion
131 : {
132 : PGFDW_V1_1 = 0,
133 : PGFDW_V1_2,
134 : };
135 :
136 : /*
137 : * SQL functions
138 : */
139 4 : PG_FUNCTION_INFO_V1(postgres_fdw_get_connections);
140 5 : PG_FUNCTION_INFO_V1(postgres_fdw_get_connections_1_2);
141 5 : PG_FUNCTION_INFO_V1(postgres_fdw_disconnect);
142 5 : PG_FUNCTION_INFO_V1(postgres_fdw_disconnect_all);
143 13 : PG_FUNCTION_INFO_V1(postgres_fdw_connection);
144 :
145 : /* prototypes of private functions */
146 : static void make_new_connection(ConnCacheEntry *entry, UserMapping *user);
147 : static PGconn *connect_pg_server(ForeignServer *server, UserMapping *user);
148 : static void disconnect_pg_server(ConnCacheEntry *entry);
149 : static void check_conn_params(const char **keywords, const char **values, UserMapping *user);
150 : static void configure_remote_session(PGconn *conn);
151 : static void do_sql_command_begin(PGconn *conn, const char *sql);
152 : static void do_sql_command_end(PGconn *conn, const char *sql,
153 : bool consume_input);
154 : static void begin_remote_xact(ConnCacheEntry *entry);
155 : static void pgfdw_report_internal(int elevel, PGresult *res, PGconn *conn,
156 : const char *sql);
157 : static void pgfdw_xact_callback(XactEvent event, void *arg);
158 : static void pgfdw_subxact_callback(SubXactEvent event,
159 : SubTransactionId mySubid,
160 : SubTransactionId parentSubid,
161 : void *arg);
162 : static void pgfdw_inval_callback(Datum arg, SysCacheIdentifier cacheid,
163 : uint32 hashvalue);
164 : static void pgfdw_reject_incomplete_xact_state_change(ConnCacheEntry *entry);
165 : static void pgfdw_reset_xact_state(ConnCacheEntry *entry, bool toplevel);
166 : static bool pgfdw_cancel_query(PGconn *conn);
167 : static bool pgfdw_cancel_query_begin(PGconn *conn, TimestampTz endtime);
168 : static bool pgfdw_cancel_query_end(PGconn *conn, TimestampTz endtime,
169 : TimestampTz retrycanceltime,
170 : bool consume_input);
171 : static bool pgfdw_exec_cleanup_query(PGconn *conn, const char *query,
172 : bool ignore_errors);
173 : static bool pgfdw_exec_cleanup_query_begin(PGconn *conn, const char *query);
174 : static bool pgfdw_exec_cleanup_query_end(PGconn *conn, const char *query,
175 : TimestampTz endtime,
176 : bool consume_input,
177 : bool ignore_errors);
178 : static bool pgfdw_get_cleanup_result(PGconn *conn, TimestampTz endtime,
179 : TimestampTz retrycanceltime,
180 : PGresult **result, bool *timed_out);
181 : static void pgfdw_abort_cleanup(ConnCacheEntry *entry, bool toplevel);
182 : static bool pgfdw_abort_cleanup_begin(ConnCacheEntry *entry, bool toplevel,
183 : List **pending_entries,
184 : List **cancel_requested);
185 : static void pgfdw_finish_pre_commit_cleanup(List *pending_entries);
186 : static void pgfdw_finish_pre_subcommit_cleanup(List *pending_entries,
187 : int curlevel);
188 : static void pgfdw_finish_abort_cleanup(List *pending_entries,
189 : List *cancel_requested,
190 : bool toplevel);
191 : static void pgfdw_security_check(const char **keywords, const char **values,
192 : UserMapping *user, PGconn *conn);
193 : static bool UserMappingPasswordRequired(UserMapping *user);
194 : static bool UseScramPassthrough(ForeignServer *server, UserMapping *user);
195 : static bool disconnect_cached_connections(Oid serverid);
196 : static void postgres_fdw_get_connections_internal(FunctionCallInfo fcinfo,
197 : enum pgfdwVersion api_version);
198 : static int pgfdw_conn_check(PGconn *conn);
199 : static bool pgfdw_conn_checkable(void);
200 : static bool pgfdw_has_required_scram_options(const char **keywords, const char **values);
201 :
202 : /*
203 : * Get a PGconn which can be used to execute queries on the remote PostgreSQL
204 : * server with the user's authorization. A new connection is established
205 : * if we don't already have a suitable one, and a transaction is opened at
206 : * the right subtransaction nesting depth if we didn't do that already.
207 : *
208 : * will_prep_stmt must be true if caller intends to create any prepared
209 : * statements. Since those don't go away automatically at transaction end
210 : * (not even on error), we need this flag to cue manual cleanup.
211 : *
212 : * If state is not NULL, *state receives the per-connection state associated
213 : * with the PGconn.
214 : */
215 : PGconn *
216 2296 : GetConnection(UserMapping *user, bool will_prep_stmt, PgFdwConnState **state)
217 : {
218 : bool found;
219 2296 : bool retry = false;
220 : ConnCacheEntry *entry;
221 : ConnCacheKey key;
222 2296 : MemoryContext ccxt = CurrentMemoryContext;
223 :
224 : /* First time through, initialize connection cache hashtable */
225 2296 : if (ConnectionHash == NULL)
226 : {
227 : HASHCTL ctl;
228 :
229 13 : if (pgfdw_we_get_result == 0)
230 13 : pgfdw_we_get_result =
231 13 : WaitEventExtensionNew("PostgresFdwGetResult");
232 :
233 13 : ctl.keysize = sizeof(ConnCacheKey);
234 13 : ctl.entrysize = sizeof(ConnCacheEntry);
235 13 : ConnectionHash = hash_create("postgres_fdw connections", 8,
236 : &ctl,
237 : HASH_ELEM | HASH_BLOBS);
238 :
239 : /*
240 : * Register some callback functions that manage connection cleanup.
241 : * This should be done just once in each backend.
242 : */
243 13 : RegisterXactCallback(pgfdw_xact_callback, NULL);
244 13 : RegisterSubXactCallback(pgfdw_subxact_callback, NULL);
245 13 : CacheRegisterSyscacheCallback(FOREIGNSERVEROID,
246 : pgfdw_inval_callback, (Datum) 0);
247 13 : CacheRegisterSyscacheCallback(USERMAPPINGOID,
248 : pgfdw_inval_callback, (Datum) 0);
249 : }
250 :
251 : /* Set flag that we did GetConnection during the current transaction */
252 2296 : xact_got_connection = true;
253 :
254 : /* Create hash key for the entry. Assume no pad bytes in key struct */
255 2296 : key = user->umid;
256 :
257 : /*
258 : * Find or create cached entry for requested connection.
259 : */
260 2296 : entry = hash_search(ConnectionHash, &key, HASH_ENTER, &found);
261 2296 : if (!found)
262 : {
263 : /*
264 : * We need only clear "conn" here; remaining fields will be filled
265 : * later when "conn" is set.
266 : */
267 24 : entry->conn = NULL;
268 : }
269 :
270 : /* Reject further use of connections which failed abort cleanup. */
271 2296 : pgfdw_reject_incomplete_xact_state_change(entry);
272 :
273 : /*
274 : * If the connection needs to be remade due to invalidation, disconnect as
275 : * soon as we're out of all transactions.
276 : */
277 2294 : if (entry->conn != NULL && entry->invalidated && entry->xact_depth == 0)
278 : {
279 0 : elog(DEBUG3, "closing connection %p for option changes to take effect",
280 : entry->conn);
281 0 : disconnect_pg_server(entry);
282 : }
283 :
284 : /*
285 : * If cache entry doesn't have a connection, we have to establish a new
286 : * connection. (If connect_pg_server throws an error, the cache entry
287 : * will remain in a valid empty state, ie conn == NULL.)
288 : */
289 2294 : if (entry->conn == NULL)
290 86 : make_new_connection(entry, user);
291 :
292 : /*
293 : * We check the health of the cached connection here when using it. In
294 : * cases where we're out of all transactions, if a broken connection is
295 : * detected, we try to reestablish a new connection later.
296 : */
297 2285 : PG_TRY();
298 : {
299 : /* Process a pending asynchronous request if any. */
300 2285 : if (entry->state.pendingAreq)
301 0 : process_pending_request(entry->state.pendingAreq);
302 : /* Start a new transaction or subtransaction if needed. */
303 2285 : begin_remote_xact(entry);
304 : }
305 3 : PG_CATCH();
306 : {
307 3 : MemoryContext ecxt = MemoryContextSwitchTo(ccxt);
308 3 : ErrorData *errdata = CopyErrorData();
309 :
310 : /*
311 : * Determine whether to try to reestablish the connection.
312 : *
313 : * After a broken connection is detected in libpq, any error other
314 : * than connection failure (e.g., out-of-memory) can be thrown
315 : * somewhere between return from libpq and the expected ereport() call
316 : * in pgfdw_report_error(). In this case, since PQstatus() indicates
317 : * CONNECTION_BAD, checking only PQstatus() causes the false detection
318 : * of connection failure. To avoid this, we also verify that the
319 : * error's sqlstate is ERRCODE_CONNECTION_FAILURE. Note that also
320 : * checking only the sqlstate can cause another false detection
321 : * because pgfdw_report_error() may report ERRCODE_CONNECTION_FAILURE
322 : * for any libpq-originated error condition.
323 : */
324 3 : if (errdata->sqlerrcode != ERRCODE_CONNECTION_FAILURE ||
325 3 : PQstatus(entry->conn) != CONNECTION_BAD ||
326 3 : entry->xact_depth > 0)
327 : {
328 1 : MemoryContextSwitchTo(ecxt);
329 1 : PG_RE_THROW();
330 : }
331 :
332 : /* Clean up the error state */
333 2 : FlushErrorState();
334 2 : FreeErrorData(errdata);
335 2 : errdata = NULL;
336 :
337 2 : retry = true;
338 : }
339 2284 : PG_END_TRY();
340 :
341 : /*
342 : * If a broken connection is detected, disconnect it, reestablish a new
343 : * connection and retry a new remote transaction. If connection failure is
344 : * reported again, we give up getting a connection.
345 : */
346 2284 : if (retry)
347 : {
348 : Assert(entry->xact_depth == 0);
349 :
350 2 : ereport(DEBUG3,
351 : (errmsg_internal("could not start remote transaction on connection %p",
352 : entry->conn)),
353 : errdetail_internal("%s", pchomp(PQerrorMessage(entry->conn))));
354 :
355 2 : elog(DEBUG3, "closing connection %p to reestablish a new one",
356 : entry->conn);
357 2 : disconnect_pg_server(entry);
358 :
359 2 : make_new_connection(entry, user);
360 :
361 2 : begin_remote_xact(entry);
362 : }
363 :
364 : /* Remember if caller will prepare statements */
365 2284 : entry->have_prep_stmt |= will_prep_stmt;
366 :
367 : /* If caller needs access to the per-connection state, return it. */
368 2284 : if (state)
369 782 : *state = &entry->state;
370 :
371 2284 : return entry->conn;
372 : }
373 :
374 : /*
375 : * Reset all transient state fields in the cached connection entry and
376 : * establish new connection to the remote server.
377 : */
378 : static void
379 88 : make_new_connection(ConnCacheEntry *entry, UserMapping *user)
380 : {
381 88 : ForeignServer *server = GetForeignServer(user->serverid);
382 : ListCell *lc;
383 :
384 : Assert(entry->conn == NULL);
385 :
386 : /* Reset all transient state fields, to be sure all are clean */
387 88 : entry->xact_depth = 0;
388 88 : entry->xact_read_only = false;
389 88 : entry->have_prep_stmt = false;
390 88 : entry->have_error = false;
391 88 : entry->changing_xact_state = false;
392 88 : entry->invalidated = false;
393 88 : entry->serverid = server->serverid;
394 88 : entry->server_hashvalue =
395 88 : GetSysCacheHashValue1(FOREIGNSERVEROID,
396 : ObjectIdGetDatum(server->serverid));
397 88 : entry->mapping_hashvalue =
398 88 : GetSysCacheHashValue1(USERMAPPINGOID,
399 : ObjectIdGetDatum(user->umid));
400 88 : memset(&entry->state, 0, sizeof(entry->state));
401 :
402 : /*
403 : * Determine whether to keep the connection that we're about to make here
404 : * open even after the transaction using it ends, so that the subsequent
405 : * transactions can re-use it.
406 : *
407 : * By default, all the connections to any foreign servers are kept open.
408 : *
409 : * Also determine whether to commit/abort (sub)transactions opened on the
410 : * remote server in parallel at (sub)transaction end, which is disabled by
411 : * default.
412 : *
413 : * Note: it's enough to determine these only when making a new connection
414 : * because if these settings for it are changed, it will be closed and
415 : * re-made later.
416 : */
417 88 : entry->keep_connections = true;
418 88 : entry->parallel_commit = false;
419 88 : entry->parallel_abort = false;
420 410 : foreach(lc, server->options)
421 : {
422 322 : DefElem *def = (DefElem *) lfirst(lc);
423 :
424 322 : if (strcmp(def->defname, "keep_connections") == 0)
425 16 : entry->keep_connections = defGetBoolean(def);
426 306 : else if (strcmp(def->defname, "parallel_commit") == 0)
427 2 : entry->parallel_commit = defGetBoolean(def);
428 304 : else if (strcmp(def->defname, "parallel_abort") == 0)
429 2 : entry->parallel_abort = defGetBoolean(def);
430 : }
431 :
432 : /* Now try to make the connection */
433 88 : entry->conn = connect_pg_server(server, user);
434 :
435 79 : elog(DEBUG3, "new postgres_fdw connection %p for server \"%s\" (user mapping oid %u, userid %u)",
436 : entry->conn, server->servername, user->umid, user->userid);
437 79 : }
438 :
439 : /*
440 : * Check that non-superuser has used password or delegated credentials
441 : * to establish connection; otherwise, he's piggybacking on the
442 : * postgres server's user identity. See also dblink_security_check()
443 : * in contrib/dblink and check_conn_params.
444 : */
445 : static void
446 81 : pgfdw_security_check(const char **keywords, const char **values, UserMapping *user, PGconn *conn)
447 : {
448 : /* Superusers bypass the check */
449 81 : if (superuser_arg(user->userid))
450 73 : return;
451 :
452 : #ifdef ENABLE_GSS
453 : /* Connected via GSSAPI with delegated credentials- all good. */
454 : if (PQconnectionUsedGSSAPI(conn) && be_gssapi_get_delegation(MyProcPort))
455 : return;
456 : #endif
457 :
458 : /* Ok if superuser set PW required false. */
459 8 : if (!UserMappingPasswordRequired(user))
460 2 : return;
461 :
462 : /* Connected via PW, with PW required true, and provided non-empty PW. */
463 6 : if (PQconnectionUsedPassword(conn))
464 : {
465 : /* ok if params contain a non-empty password */
466 40 : for (int i = 0; keywords[i] != NULL; i++)
467 : {
468 36 : if (strcmp(keywords[i], "password") == 0 && values[i][0] != '\0')
469 0 : return;
470 : }
471 : }
472 :
473 : /*
474 : * Ok if SCRAM pass-through is being used and all required SCRAM options
475 : * are set correctly. If pgfdw_has_required_scram_options returns true we
476 : * assume that UseScramPassthrough is also true since SCRAM options are
477 : * only set when UseScramPassthrough is enabled.
478 : */
479 6 : if (MyProcPort != NULL && MyProcPort->has_scram_keys && pgfdw_has_required_scram_options(keywords, values))
480 4 : return;
481 :
482 2 : ereport(ERROR,
483 : (errcode(ERRCODE_S_R_E_PROHIBITED_SQL_STATEMENT_ATTEMPTED),
484 : errmsg("password or GSSAPI delegated credentials required"),
485 : errdetail("Non-superuser cannot connect if the server does not request a password or use GSSAPI with delegated credentials."),
486 : errhint("Target server's authentication method must be changed or password_required=false set in the user mapping attributes.")));
487 : }
488 :
489 : /*
490 : * Construct connection params from generic options of ForeignServer and
491 : * UserMapping. (Some of them might not be libpq options, in which case we'll
492 : * just waste a few array slots.)
493 : */
494 : static void
495 97 : construct_connection_params(ForeignServer *server, UserMapping *user,
496 : const char ***p_keywords, const char ***p_values,
497 : char **p_appname)
498 : {
499 : const char **keywords;
500 : const char **values;
501 97 : char *appname = NULL;
502 : int n;
503 :
504 : /*
505 : * Add 4 extra slots for application_name, fallback_application_name,
506 : * client_encoding, end marker, and 3 extra slots for scram keys and
507 : * required scram pass-through options.
508 : */
509 97 : n = list_length(server->options) + list_length(user->options) + 4 + 3;
510 97 : keywords = (const char **) palloc(n * sizeof(char *));
511 97 : values = (const char **) palloc(n * sizeof(char *));
512 :
513 97 : n = 0;
514 194 : n += ExtractConnectionOptions(server->options,
515 97 : keywords + n, values + n);
516 194 : n += ExtractConnectionOptions(user->options,
517 97 : keywords + n, values + n);
518 :
519 : /*
520 : * Use pgfdw_application_name as application_name if set.
521 : *
522 : * PQconnectdbParams() processes the parameter arrays from start to end.
523 : * If any key word is repeated, the last value is used. Therefore note
524 : * that pgfdw_application_name must be added to the arrays after options
525 : * of ForeignServer are, so that it can override application_name set in
526 : * ForeignServer.
527 : */
528 97 : if (pgfdw_application_name && *pgfdw_application_name != '\0')
529 : {
530 1 : keywords[n] = "application_name";
531 1 : values[n] = pgfdw_application_name;
532 1 : n++;
533 : }
534 :
535 : /*
536 : * Search the parameter arrays to find application_name setting, and
537 : * replace escape sequences in it with status information if found. The
538 : * arrays are searched backwards because the last value is used if
539 : * application_name is repeatedly set.
540 : */
541 279 : for (int i = n - 1; i >= 0; i--)
542 : {
543 209 : if (strcmp(keywords[i], "application_name") == 0 &&
544 27 : *(values[i]) != '\0')
545 : {
546 : /*
547 : * Use this application_name setting if it's not empty string even
548 : * after any escape sequences in it are replaced.
549 : */
550 27 : appname = process_pgfdw_appname(values[i]);
551 27 : if (appname[0] != '\0')
552 : {
553 27 : values[i] = appname;
554 27 : break;
555 : }
556 :
557 : /*
558 : * This empty application_name is not used, so we set values[i] to
559 : * NULL and keep searching the array to find the next one.
560 : */
561 0 : values[i] = NULL;
562 0 : pfree(appname);
563 0 : appname = NULL;
564 : }
565 : }
566 :
567 97 : *p_appname = appname;
568 :
569 : /* Use "postgres_fdw" as fallback_application_name */
570 97 : keywords[n] = "fallback_application_name";
571 97 : values[n] = "postgres_fdw";
572 97 : n++;
573 :
574 : /* Set client_encoding so that libpq can convert encoding properly. */
575 97 : keywords[n] = "client_encoding";
576 97 : values[n] = GetDatabaseEncodingName();
577 97 : n++;
578 :
579 : /* Add required SCRAM pass-through connection options if it's enabled. */
580 97 : if (MyProcPort != NULL && MyProcPort->has_scram_keys && UseScramPassthrough(server, user))
581 : {
582 : int len;
583 : int encoded_len;
584 :
585 6 : keywords[n] = "scram_client_key";
586 6 : len = pg_b64_enc_len(sizeof(MyProcPort->scram_ClientKey));
587 : /* don't forget the zero-terminator */
588 6 : values[n] = palloc0(len + 1);
589 6 : encoded_len = pg_b64_encode(MyProcPort->scram_ClientKey,
590 : sizeof(MyProcPort->scram_ClientKey),
591 6 : (char *) values[n], len);
592 6 : if (encoded_len < 0)
593 0 : elog(ERROR, "could not encode SCRAM client key");
594 6 : n++;
595 :
596 6 : keywords[n] = "scram_server_key";
597 6 : len = pg_b64_enc_len(sizeof(MyProcPort->scram_ServerKey));
598 : /* don't forget the zero-terminator */
599 6 : values[n] = palloc0(len + 1);
600 6 : encoded_len = pg_b64_encode(MyProcPort->scram_ServerKey,
601 : sizeof(MyProcPort->scram_ServerKey),
602 6 : (char *) values[n], len);
603 6 : if (encoded_len < 0)
604 0 : elog(ERROR, "could not encode SCRAM server key");
605 6 : n++;
606 :
607 : /*
608 : * Require scram-sha-256 to ensure that no other auth method is used
609 : * when connecting with foreign server.
610 : */
611 6 : keywords[n] = "require_auth";
612 6 : values[n] = "scram-sha-256";
613 6 : n++;
614 : }
615 :
616 97 : keywords[n] = values[n] = NULL;
617 :
618 : /* Verify the set of connection parameters. */
619 97 : check_conn_params(keywords, values, user);
620 :
621 94 : *p_keywords = keywords;
622 94 : *p_values = values;
623 94 : }
624 :
625 : /*
626 : * Connect to remote server using specified server and user mapping properties.
627 : */
628 : static PGconn *
629 88 : connect_pg_server(ForeignServer *server, UserMapping *user)
630 : {
631 88 : PGconn *volatile conn = NULL;
632 :
633 : /*
634 : * Use PG_TRY block to ensure closing connection on error.
635 : */
636 88 : PG_TRY();
637 : {
638 : const char **keywords;
639 : const char **values;
640 : char *appname;
641 : PGconn *start_conn;
642 :
643 88 : construct_connection_params(server, user, &keywords, &values, &appname);
644 :
645 : /* first time, allocate or get the custom wait event */
646 85 : if (pgfdw_we_connect == 0)
647 12 : pgfdw_we_connect = WaitEventExtensionNew("PostgresFdwConnect");
648 :
649 : /* OK to make connection */
650 : start_conn =
651 85 : libpqsrv_connect_params_start(keywords, values,
652 : /* expand_dbname = */ false);
653 85 : PQsetNoticeReceiver(start_conn, libpqsrv_notice_receiver,
654 : "received message via remote connection");
655 85 : libpqsrv_connect_complete(start_conn, pgfdw_we_connect);
656 85 : conn = start_conn;
657 :
658 85 : if (!conn || PQstatus(conn) != CONNECTION_OK)
659 4 : ereport(ERROR,
660 : (errcode(ERRCODE_SQLCLIENT_UNABLE_TO_ESTABLISH_SQLCONNECTION),
661 : errmsg("could not connect to server \"%s\"",
662 : server->servername),
663 : errdetail_internal("%s", pchomp(PQerrorMessage(conn)))));
664 :
665 : /* Perform post-connection security checks. */
666 81 : pgfdw_security_check(keywords, values, user, conn);
667 :
668 : /* Prepare new session for use */
669 79 : configure_remote_session(conn);
670 :
671 79 : if (appname != NULL)
672 26 : pfree(appname);
673 79 : pfree(keywords);
674 79 : pfree(values);
675 : }
676 9 : PG_CATCH();
677 : {
678 9 : libpqsrv_disconnect(conn);
679 9 : PG_RE_THROW();
680 : }
681 79 : PG_END_TRY();
682 :
683 79 : return conn;
684 : }
685 :
686 : /*
687 : * Disconnect any open connection for a connection cache entry.
688 : */
689 : static void
690 70 : disconnect_pg_server(ConnCacheEntry *entry)
691 : {
692 70 : if (entry->conn != NULL)
693 : {
694 70 : libpqsrv_disconnect(entry->conn);
695 70 : entry->conn = NULL;
696 : }
697 70 : }
698 :
699 : /*
700 : * Check and return the value of password_required, if defined; otherwise,
701 : * return true, which is the default value of it. The mapping has been
702 : * pre-validated.
703 : */
704 : static bool
705 18 : UserMappingPasswordRequired(UserMapping *user)
706 : {
707 : ListCell *cell;
708 :
709 33 : foreach(cell, user->options)
710 : {
711 18 : DefElem *def = (DefElem *) lfirst(cell);
712 :
713 18 : if (strcmp(def->defname, "password_required") == 0)
714 3 : return defGetBoolean(def);
715 : }
716 :
717 15 : return true;
718 : }
719 :
720 : /*
721 : * Return whether SCRAM pass-through is enabled.
722 : *
723 : * If use_scram_passthrough is specified in both the foreign server
724 : * and the user mapping, the user mapping setting takes precedence.
725 : */
726 : static bool
727 7 : UseScramPassthrough(ForeignServer *server, UserMapping *user)
728 : {
729 : ListCell *cell;
730 :
731 14 : foreach(cell, user->options)
732 : {
733 8 : DefElem *def = (DefElem *) lfirst(cell);
734 :
735 8 : if (strcmp(def->defname, "use_scram_passthrough") == 0)
736 1 : return defGetBoolean(def);
737 : }
738 :
739 24 : foreach(cell, server->options)
740 : {
741 24 : DefElem *def = (DefElem *) lfirst(cell);
742 :
743 24 : if (strcmp(def->defname, "use_scram_passthrough") == 0)
744 6 : return defGetBoolean(def);
745 : }
746 :
747 0 : return false;
748 : }
749 :
750 : /*
751 : * For non-superusers, insist that the connstr specify a password or that the
752 : * user provided their own GSSAPI delegated credentials. This
753 : * prevents a password from being picked up from .pgpass, a service file, the
754 : * environment, etc. We don't want the postgres user's passwords,
755 : * certificates, etc to be accessible to non-superusers. (See also
756 : * dblink_connstr_check in contrib/dblink.)
757 : */
758 : static void
759 97 : check_conn_params(const char **keywords, const char **values, UserMapping *user)
760 : {
761 : int i;
762 :
763 : /* no check required if superuser */
764 97 : if (superuser_arg(user->userid))
765 84 : return;
766 :
767 : #ifdef ENABLE_GSS
768 : /* ok if the user provided their own delegated credentials */
769 : if (be_gssapi_get_delegation(MyProcPort))
770 : return;
771 : #endif
772 :
773 : /* ok if params contain a non-empty password */
774 91 : for (i = 0; keywords[i] != NULL; i++)
775 : {
776 81 : if (strcmp(keywords[i], "password") == 0 && values[i][0] != '\0')
777 3 : return;
778 : }
779 :
780 : /* ok if the superuser explicitly said so at user mapping creation time */
781 10 : if (!UserMappingPasswordRequired(user))
782 1 : return;
783 :
784 : /*
785 : * Ok if SCRAM pass-through is being used and all required scram options
786 : * are set correctly. If pgfdw_has_required_scram_options returns true we
787 : * assume that UseScramPassthrough is also true since SCRAM options are
788 : * only set when UseScramPassthrough is enabled.
789 : */
790 9 : if (MyProcPort != NULL && MyProcPort->has_scram_keys && pgfdw_has_required_scram_options(keywords, values))
791 6 : return;
792 :
793 3 : ereport(ERROR,
794 : (errcode(ERRCODE_S_R_E_PROHIBITED_SQL_STATEMENT_ATTEMPTED),
795 : errmsg("password or GSSAPI delegated credentials required"),
796 : errdetail("Non-superusers must delegate GSSAPI credentials, provide a password, or enable SCRAM pass-through in user mapping.")));
797 : }
798 :
799 : /*
800 : * Issue SET commands to make sure remote session is configured properly.
801 : *
802 : * We do this just once at connection, assuming nothing will change the
803 : * values later. Since we'll never send volatile function calls to the
804 : * remote, there shouldn't be any way to break this assumption from our end.
805 : * It's possible to think of ways to break it at the remote end, eg making
806 : * a foreign table point to a view that includes a set_config call ---
807 : * but once you admit the possibility of a malicious view definition,
808 : * there are any number of ways to break things.
809 : */
810 : static void
811 79 : configure_remote_session(PGconn *conn)
812 : {
813 79 : int remoteversion = PQserverVersion(conn);
814 :
815 : /* Force the search path to contain only pg_catalog (see deparse.c) */
816 79 : do_sql_command(conn, "SET search_path = pg_catalog");
817 :
818 : /*
819 : * Set remote timezone; this is basically just cosmetic, since all
820 : * transmitted and returned timestamptzs should specify a zone explicitly
821 : * anyway. However it makes the regression test outputs more predictable.
822 : *
823 : * We don't risk setting remote zone equal to ours, since the remote
824 : * server might use a different timezone database. Instead, use GMT
825 : * (quoted, because very old servers are picky about case). That's
826 : * guaranteed to work regardless of the remote's timezone database,
827 : * because pg_tzset() hard-wires it (at least in PG 9.2 and later).
828 : */
829 79 : do_sql_command(conn, "SET timezone = 'GMT'");
830 :
831 : /*
832 : * Set values needed to ensure unambiguous data output from remote. (This
833 : * logic should match what pg_dump does. See also set_transmission_modes
834 : * in postgres_fdw.c.)
835 : */
836 79 : do_sql_command(conn, "SET datestyle = ISO");
837 79 : if (remoteversion >= 80400)
838 79 : do_sql_command(conn, "SET intervalstyle = postgres");
839 79 : if (remoteversion >= 90000)
840 79 : do_sql_command(conn, "SET extra_float_digits = 3");
841 : else
842 0 : do_sql_command(conn, "SET extra_float_digits = 2");
843 79 : }
844 :
845 : /*
846 : * Convenience subroutine to issue a non-data-returning SQL command to remote
847 : */
848 : void
849 1925 : do_sql_command(PGconn *conn, const char *sql)
850 : {
851 1925 : do_sql_command_begin(conn, sql);
852 1925 : do_sql_command_end(conn, sql, false);
853 1921 : }
854 :
855 : static void
856 1943 : do_sql_command_begin(PGconn *conn, const char *sql)
857 : {
858 1943 : if (!PQsendQuery(conn, sql))
859 0 : pgfdw_report_error(NULL, conn, sql);
860 1943 : }
861 :
862 : static void
863 1943 : do_sql_command_end(PGconn *conn, const char *sql, bool consume_input)
864 : {
865 : PGresult *res;
866 :
867 : /*
868 : * If requested, consume whatever data is available from the socket. (Note
869 : * that if all data is available, this allows pgfdw_get_result to call
870 : * PQgetResult without forcing the overhead of WaitLatchOrSocket, which
871 : * would be large compared to the overhead of PQconsumeInput.)
872 : */
873 1943 : if (consume_input && !PQconsumeInput(conn))
874 0 : pgfdw_report_error(NULL, conn, sql);
875 1943 : res = pgfdw_get_result(conn);
876 1943 : if (PQresultStatus(res) != PGRES_COMMAND_OK)
877 4 : pgfdw_report_error(res, conn, sql);
878 1939 : PQclear(res);
879 1939 : }
880 :
881 : /*
882 : * Start remote transaction or subtransaction, if needed.
883 : *
884 : * Note that we always use at least REPEATABLE READ in the remote session.
885 : * This is so that, if a query initiates multiple scans of the same or
886 : * different foreign tables, we will get snapshot-consistent results from
887 : * those scans. A disadvantage is that we can't provide sane emulation of
888 : * READ COMMITTED behavior --- it would be nice if we had some other way to
889 : * control which remote queries share a snapshot.
890 : *
891 : * Note also that we always start the remote transaction with the same
892 : * read/write and deferrable properties as the local transaction, and start
893 : * the remote subtransaction with the same read/write property as the local
894 : * subtransaction.
895 : */
896 : static void
897 2287 : begin_remote_xact(ConnCacheEntry *entry)
898 : {
899 2287 : int curlevel = GetCurrentTransactionNestLevel();
900 :
901 : /*
902 : * If the current local (sub)transaction is read-only, set the topmost
903 : * read-only local transaction's nesting level if we haven't yet.
904 : *
905 : * Note: once it's set, it's retained until the topmost read-only local
906 : * transaction is committed/aborted (see pgfdw_xact_callback and
907 : * pgfdw_subxact_callback).
908 : */
909 2287 : if (XactReadOnly)
910 : {
911 10 : if (read_only_level == 0)
912 9 : read_only_level = GetTopReadOnlyTransactionNestLevel();
913 : Assert(read_only_level > 0);
914 : }
915 : else
916 : Assert(read_only_level == 0);
917 :
918 : /*
919 : * Start main transaction if we haven't yet; otherwise, change the current
920 : * remote (sub)transaction's read/write mode if needed.
921 : */
922 2287 : if (entry->xact_depth <= 0)
923 : {
924 : /*
925 : * This is the case when we haven't yet started a main transaction.
926 : */
927 : StringInfoData sql;
928 782 : bool ro = (read_only_level == 1);
929 :
930 782 : elog(DEBUG3, "starting remote transaction on connection %p",
931 : entry->conn);
932 :
933 782 : initStringInfo(&sql);
934 782 : appendStringInfoString(&sql, "START TRANSACTION ISOLATION LEVEL ");
935 782 : if (IsolationIsSerializable())
936 3 : appendStringInfoString(&sql, "SERIALIZABLE");
937 : else
938 779 : appendStringInfoString(&sql, "REPEATABLE READ");
939 782 : if (ro)
940 3 : appendStringInfoString(&sql, " READ ONLY");
941 782 : if (XactDeferrable)
942 2 : appendStringInfoString(&sql, " DEFERRABLE");
943 782 : entry->changing_xact_state = true;
944 782 : do_sql_command(entry->conn, sql.data);
945 780 : entry->xact_depth = 1;
946 780 : if (ro)
947 : {
948 : Assert(!entry->xact_read_only);
949 3 : entry->xact_read_only = true;
950 : }
951 780 : entry->changing_xact_state = false;
952 : }
953 1505 : else if (!entry->xact_read_only)
954 : {
955 : /*
956 : * The remote (sub)transaction has been opened in read-write mode.
957 : */
958 : Assert(read_only_level == 0 ||
959 : entry->xact_depth <= read_only_level);
960 :
961 : /*
962 : * If its nesting depth matches read_only_level, it means that the
963 : * local read-write (sub)transaction that started it has changed to
964 : * read-only after that; in which case change it to read-only as well.
965 : * Otherwise, the local (sub)transaction is still read-write, so there
966 : * is no need to do anything.
967 : */
968 1504 : if (entry->xact_depth == read_only_level)
969 : {
970 4 : entry->changing_xact_state = true;
971 4 : do_sql_command(entry->conn, "SET transaction_read_only = on");
972 4 : entry->xact_read_only = true;
973 4 : entry->changing_xact_state = false;
974 : }
975 : }
976 : else
977 : {
978 : /*
979 : * The remote (sub)transaction has been opened in read-only mode.
980 : */
981 : Assert(read_only_level > 0 &&
982 : entry->xact_depth >= read_only_level);
983 :
984 : /*
985 : * The local read-only (sub)transaction that started it is guaranteed
986 : * to be still read-only (see check_transaction_read_only), so there
987 : * is no need to do anything.
988 : */
989 : }
990 :
991 : /*
992 : * If we're in a subtransaction, stack up savepoints to match our level.
993 : * This ensures we can rollback just the desired effects when a
994 : * subtransaction aborts.
995 : */
996 2306 : while (entry->xact_depth < curlevel)
997 : {
998 : StringInfoData sql;
999 22 : bool ro = (entry->xact_depth + 1 == read_only_level);
1000 :
1001 22 : initStringInfo(&sql);
1002 22 : appendStringInfo(&sql, "SAVEPOINT s%d", entry->xact_depth + 1);
1003 22 : if (ro)
1004 2 : appendStringInfoString(&sql, "; SET transaction_read_only = on");
1005 22 : entry->changing_xact_state = true;
1006 22 : do_sql_command(entry->conn, sql.data);
1007 21 : entry->xact_depth++;
1008 21 : if (ro)
1009 : {
1010 : Assert(!entry->xact_read_only);
1011 2 : entry->xact_read_only = true;
1012 : }
1013 21 : entry->changing_xact_state = false;
1014 : }
1015 2284 : }
1016 :
1017 : /*
1018 : * Release connection reference count created by calling GetConnection.
1019 : */
1020 : void
1021 2209 : ReleaseConnection(PGconn *conn)
1022 : {
1023 : /*
1024 : * Currently, we don't actually track connection references because all
1025 : * cleanup is managed on a transaction or subtransaction basis instead. So
1026 : * there's nothing to do here.
1027 : */
1028 2209 : }
1029 :
1030 : /*
1031 : * Assign a "unique" number for a cursor.
1032 : *
1033 : * These really only need to be unique per connection within a transaction.
1034 : * For the moment we ignore the per-connection point and assign them across
1035 : * all connections in the transaction, but we ask for the connection to be
1036 : * supplied in case we want to refine that.
1037 : *
1038 : * Note that even if wraparound happens in a very long transaction, actual
1039 : * collisions are highly improbable; just be sure to use %u not %d to print.
1040 : */
1041 : unsigned int
1042 578 : GetCursorNumber(PGconn *conn)
1043 : {
1044 578 : return ++cursor_number;
1045 : }
1046 :
1047 : /*
1048 : * Assign a "unique" number for a prepared statement.
1049 : *
1050 : * This works much like GetCursorNumber, except that we never reset the counter
1051 : * within a session. That's because we can't be 100% sure we've gotten rid
1052 : * of all prepared statements on all connections, and it's not really worth
1053 : * increasing the risk of prepared-statement name collisions by resetting.
1054 : */
1055 : unsigned int
1056 188 : GetPrepStmtNumber(PGconn *conn)
1057 : {
1058 188 : return ++prep_stmt_number;
1059 : }
1060 :
1061 : /*
1062 : * Submit a query and wait for the result.
1063 : *
1064 : * Since we don't use non-blocking mode, this can't process interrupts while
1065 : * pushing the query text to the server. That risk is relatively small, so we
1066 : * ignore that for now.
1067 : *
1068 : * Caller is responsible for the error handling on the result.
1069 : */
1070 : PGresult *
1071 4188 : pgfdw_exec_query(PGconn *conn, const char *query, PgFdwConnState *state)
1072 : {
1073 : /* First, process a pending asynchronous request, if any. */
1074 4188 : if (state && state->pendingAreq)
1075 4 : process_pending_request(state->pendingAreq);
1076 :
1077 4188 : if (!PQsendQuery(conn, query))
1078 1 : return NULL;
1079 4187 : return pgfdw_get_result(conn);
1080 : }
1081 :
1082 : /*
1083 : * Wrap libpqsrv_get_result_last(), adding wait event.
1084 : *
1085 : * Caller is responsible for the error handling on the result.
1086 : */
1087 : PGresult *
1088 8453 : pgfdw_get_result(PGconn *conn)
1089 : {
1090 8453 : return libpqsrv_get_result_last(conn, pgfdw_we_get_result);
1091 : }
1092 :
1093 : /*
1094 : * Report an error we got from the remote server.
1095 : *
1096 : * Callers should use pgfdw_report_error() to throw an error, or use
1097 : * pgfdw_report() for lesser message levels. (We make this distinction
1098 : * so that pgfdw_report_error() can be marked noreturn.)
1099 : *
1100 : * res: PGresult containing the error (might be NULL)
1101 : * conn: connection we did the query on
1102 : * sql: NULL, or text of remote command we tried to execute
1103 : *
1104 : * If "res" is not NULL, it'll be PQclear'ed here (unless we throw error,
1105 : * in which case memory context cleanup will clear it eventually).
1106 : *
1107 : * Note: callers that choose not to throw ERROR for a remote error are
1108 : * responsible for making sure that the associated ConnCacheEntry gets
1109 : * marked with have_error = true.
1110 : */
1111 : void
1112 27 : pgfdw_report_error(PGresult *res, PGconn *conn, const char *sql)
1113 : {
1114 27 : pgfdw_report_internal(ERROR, res, conn, sql);
1115 0 : pg_unreachable();
1116 : }
1117 :
1118 : void
1119 2 : pgfdw_report(int elevel, PGresult *res, PGconn *conn, const char *sql)
1120 : {
1121 : Assert(elevel < ERROR); /* use pgfdw_report_error for that */
1122 2 : pgfdw_report_internal(elevel, res, conn, sql);
1123 2 : }
1124 :
1125 : static void
1126 29 : pgfdw_report_internal(int elevel, PGresult *res, PGconn *conn,
1127 : const char *sql)
1128 : {
1129 29 : char *diag_sqlstate = PQresultErrorField(res, PG_DIAG_SQLSTATE);
1130 29 : char *message_primary = PQresultErrorField(res, PG_DIAG_MESSAGE_PRIMARY);
1131 29 : char *message_detail = PQresultErrorField(res, PG_DIAG_MESSAGE_DETAIL);
1132 29 : char *message_hint = PQresultErrorField(res, PG_DIAG_MESSAGE_HINT);
1133 29 : char *message_context = PQresultErrorField(res, PG_DIAG_CONTEXT);
1134 : int sqlstate;
1135 :
1136 29 : if (diag_sqlstate)
1137 22 : sqlstate = MAKE_SQLSTATE(diag_sqlstate[0],
1138 : diag_sqlstate[1],
1139 : diag_sqlstate[2],
1140 : diag_sqlstate[3],
1141 : diag_sqlstate[4]);
1142 : else
1143 7 : sqlstate = ERRCODE_CONNECTION_FAILURE;
1144 :
1145 : /*
1146 : * If we don't get a message from the PGresult, try the PGconn. This is
1147 : * needed because for connection-level failures, PQgetResult may just
1148 : * return NULL, not a PGresult at all.
1149 : */
1150 29 : if (message_primary == NULL)
1151 7 : message_primary = pchomp(PQerrorMessage(conn));
1152 :
1153 29 : ereport(elevel,
1154 : (errcode(sqlstate),
1155 : (message_primary != NULL && message_primary[0] != '\0') ?
1156 : errmsg_internal("%s", message_primary) :
1157 : errmsg("could not obtain message string for remote error"),
1158 : message_detail ? errdetail_internal("%s", message_detail) : 0,
1159 : message_hint ? errhint("%s", message_hint) : 0,
1160 : message_context ? errcontext("%s", message_context) : 0,
1161 : sql ? errcontext("remote SQL command: %s", sql) : 0));
1162 2 : PQclear(res);
1163 2 : }
1164 :
1165 : /*
1166 : * pgfdw_xact_callback --- cleanup at main-transaction end.
1167 : *
1168 : * This runs just late enough that it must not enter user-defined code
1169 : * locally. (Entering such code on the remote side is fine. Its remote
1170 : * COMMIT TRANSACTION may run deferred triggers.)
1171 : */
1172 : static void
1173 4263 : pgfdw_xact_callback(XactEvent event, void *arg)
1174 : {
1175 : HASH_SEQ_STATUS scan;
1176 : ConnCacheEntry *entry;
1177 4263 : List *pending_entries = NIL;
1178 4263 : List *cancel_requested = NIL;
1179 :
1180 : /* Quick exit if no connections were touched in this transaction. */
1181 4263 : if (!xact_got_connection)
1182 3512 : return;
1183 :
1184 : /*
1185 : * Scan all connection cache entries to find open remote transactions, and
1186 : * close them.
1187 : */
1188 751 : hash_seq_init(&scan, ConnectionHash);
1189 3960 : while ((entry = (ConnCacheEntry *) hash_seq_search(&scan)))
1190 : {
1191 : PGresult *res;
1192 :
1193 : /* Ignore cache entry if no open connection right now */
1194 3210 : if (entry->conn == NULL)
1195 1881 : continue;
1196 :
1197 : /* If it has an open remote transaction, try to close it */
1198 1329 : if (entry->xact_depth > 0)
1199 : {
1200 781 : elog(DEBUG3, "closing remote transaction on connection %p",
1201 : entry->conn);
1202 :
1203 781 : switch (event)
1204 : {
1205 721 : case XACT_EVENT_PARALLEL_PRE_COMMIT:
1206 : case XACT_EVENT_PRE_COMMIT:
1207 :
1208 : /*
1209 : * If abort cleanup previously failed for this connection,
1210 : * we can't issue any more commands against it.
1211 : */
1212 721 : pgfdw_reject_incomplete_xact_state_change(entry);
1213 :
1214 : /* Commit all remote transactions during pre-commit */
1215 721 : entry->changing_xact_state = true;
1216 721 : if (entry->parallel_commit)
1217 : {
1218 16 : do_sql_command_begin(entry->conn, "COMMIT TRANSACTION");
1219 16 : pending_entries = lappend(pending_entries, entry);
1220 16 : continue;
1221 : }
1222 705 : do_sql_command(entry->conn, "COMMIT TRANSACTION");
1223 705 : entry->changing_xact_state = false;
1224 :
1225 : /*
1226 : * If there were any errors in subtransactions, and we
1227 : * made prepared statements, do a DEALLOCATE ALL to make
1228 : * sure we get rid of all prepared statements. This is
1229 : * annoying and not terribly bulletproof, but it's
1230 : * probably not worth trying harder.
1231 : *
1232 : * DEALLOCATE ALL only exists in 8.3 and later, so this
1233 : * constrains how old a server postgres_fdw can
1234 : * communicate with. We intentionally ignore errors in
1235 : * the DEALLOCATE, so that we can hobble along to some
1236 : * extent with older servers (leaking prepared statements
1237 : * as we go; but we don't really support update operations
1238 : * pre-8.3 anyway).
1239 : */
1240 705 : if (entry->have_prep_stmt && entry->have_error)
1241 : {
1242 0 : res = pgfdw_exec_query(entry->conn, "DEALLOCATE ALL",
1243 : NULL);
1244 0 : PQclear(res);
1245 : }
1246 705 : entry->have_prep_stmt = false;
1247 705 : entry->have_error = false;
1248 705 : break;
1249 1 : case XACT_EVENT_PRE_PREPARE:
1250 :
1251 : /*
1252 : * We disallow any remote transactions, since it's not
1253 : * very reasonable to hold them open until the prepared
1254 : * transaction is committed. For the moment, throw error
1255 : * unconditionally; later we might allow read-only cases.
1256 : * Note that the error will cause us to come right back
1257 : * here with event == XACT_EVENT_ABORT, so we'll clean up
1258 : * the connection state at that point.
1259 : */
1260 1 : ereport(ERROR,
1261 : (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
1262 : errmsg("cannot PREPARE a transaction that has operated on postgres_fdw foreign tables")));
1263 : break;
1264 0 : case XACT_EVENT_PARALLEL_COMMIT:
1265 : case XACT_EVENT_COMMIT:
1266 : case XACT_EVENT_PREPARE:
1267 : /* Pre-commit should have closed the open transaction */
1268 0 : elog(ERROR, "missed cleaning up connection during pre-commit");
1269 : break;
1270 59 : case XACT_EVENT_PARALLEL_ABORT:
1271 : case XACT_EVENT_ABORT:
1272 : /* Rollback all remote transactions during abort */
1273 59 : if (entry->parallel_abort)
1274 : {
1275 4 : if (pgfdw_abort_cleanup_begin(entry, true,
1276 : &pending_entries,
1277 : &cancel_requested))
1278 4 : continue;
1279 : }
1280 : else
1281 55 : pgfdw_abort_cleanup(entry, true);
1282 55 : break;
1283 : }
1284 : }
1285 :
1286 : /* Reset state to show we're out of a transaction */
1287 1308 : pgfdw_reset_xact_state(entry, true);
1288 : }
1289 :
1290 : /* If there are any pending connections, finish cleaning them up */
1291 750 : if (pending_entries || cancel_requested)
1292 : {
1293 15 : if (event == XACT_EVENT_PARALLEL_PRE_COMMIT ||
1294 : event == XACT_EVENT_PRE_COMMIT)
1295 : {
1296 : Assert(cancel_requested == NIL);
1297 13 : pgfdw_finish_pre_commit_cleanup(pending_entries);
1298 : }
1299 : else
1300 : {
1301 : Assert(event == XACT_EVENT_PARALLEL_ABORT ||
1302 : event == XACT_EVENT_ABORT);
1303 2 : pgfdw_finish_abort_cleanup(pending_entries, cancel_requested,
1304 : true);
1305 : }
1306 : }
1307 :
1308 : /*
1309 : * Regardless of the event type, we can now mark ourselves as out of the
1310 : * transaction. (Note: if we are here during PRE_COMMIT or PRE_PREPARE,
1311 : * this saves a useless scan of the hashtable during COMMIT or PREPARE.)
1312 : */
1313 750 : xact_got_connection = false;
1314 :
1315 : /* Also reset cursor numbering for next transaction */
1316 750 : cursor_number = 0;
1317 :
1318 : /* Likewise for read_only_level */
1319 750 : read_only_level = 0;
1320 : }
1321 :
1322 : /*
1323 : * pgfdw_subxact_callback --- cleanup at subtransaction end.
1324 : */
1325 : static void
1326 72 : pgfdw_subxact_callback(SubXactEvent event, SubTransactionId mySubid,
1327 : SubTransactionId parentSubid, void *arg)
1328 : {
1329 : HASH_SEQ_STATUS scan;
1330 : ConnCacheEntry *entry;
1331 : int curlevel;
1332 72 : List *pending_entries = NIL;
1333 72 : List *cancel_requested = NIL;
1334 :
1335 : /* Nothing to do at subxact start, nor after commit. */
1336 72 : if (!(event == SUBXACT_EVENT_PRE_COMMIT_SUB ||
1337 : event == SUBXACT_EVENT_ABORT_SUB))
1338 43 : return;
1339 :
1340 : /* Quick exit if no connections were touched in this transaction. */
1341 29 : if (!xact_got_connection)
1342 0 : return;
1343 :
1344 : /*
1345 : * Scan all connection cache entries to find open remote subtransactions
1346 : * of the current level, and close them.
1347 : */
1348 29 : curlevel = GetCurrentTransactionNestLevel();
1349 29 : hash_seq_init(&scan, ConnectionHash);
1350 242 : while ((entry = (ConnCacheEntry *) hash_seq_search(&scan)))
1351 : {
1352 : char sql[100];
1353 :
1354 : /*
1355 : * We only care about connections with open remote subtransactions of
1356 : * the current level.
1357 : */
1358 213 : if (entry->conn == NULL || entry->xact_depth < curlevel)
1359 198 : continue;
1360 :
1361 21 : if (entry->xact_depth > curlevel)
1362 0 : elog(ERROR, "missed cleaning up remote subtransaction at level %d",
1363 : entry->xact_depth);
1364 :
1365 21 : if (event == SUBXACT_EVENT_PRE_COMMIT_SUB)
1366 : {
1367 : /*
1368 : * If abort cleanup previously failed for this connection, we
1369 : * can't issue any more commands against it.
1370 : */
1371 7 : pgfdw_reject_incomplete_xact_state_change(entry);
1372 :
1373 : /* Commit all remote subtransactions during pre-commit */
1374 7 : snprintf(sql, sizeof(sql), "RELEASE SAVEPOINT s%d", curlevel);
1375 7 : entry->changing_xact_state = true;
1376 7 : if (entry->parallel_commit)
1377 : {
1378 2 : do_sql_command_begin(entry->conn, sql);
1379 2 : pending_entries = lappend(pending_entries, entry);
1380 2 : continue;
1381 : }
1382 5 : do_sql_command(entry->conn, sql);
1383 5 : entry->changing_xact_state = false;
1384 : }
1385 : else
1386 : {
1387 : /* Rollback all remote subtransactions during abort */
1388 14 : if (entry->parallel_abort)
1389 : {
1390 4 : if (pgfdw_abort_cleanup_begin(entry, false,
1391 : &pending_entries,
1392 : &cancel_requested))
1393 4 : continue;
1394 : }
1395 : else
1396 10 : pgfdw_abort_cleanup(entry, false);
1397 : }
1398 :
1399 : /* OK, we're outta that level of subtransaction */
1400 15 : pgfdw_reset_xact_state(entry, false);
1401 : }
1402 :
1403 : /* If there are any pending connections, finish cleaning them up */
1404 29 : if (pending_entries || cancel_requested)
1405 : {
1406 3 : if (event == SUBXACT_EVENT_PRE_COMMIT_SUB)
1407 : {
1408 : Assert(cancel_requested == NIL);
1409 1 : pgfdw_finish_pre_subcommit_cleanup(pending_entries, curlevel);
1410 : }
1411 : else
1412 : {
1413 : Assert(event == SUBXACT_EVENT_ABORT_SUB);
1414 2 : pgfdw_finish_abort_cleanup(pending_entries, cancel_requested,
1415 : false);
1416 : }
1417 : }
1418 :
1419 : /* If in read_only_level, reset it */
1420 29 : if (curlevel == read_only_level)
1421 3 : read_only_level = 0;
1422 : }
1423 :
1424 : /*
1425 : * Connection invalidation callback function
1426 : *
1427 : * After a change to a pg_foreign_server or pg_user_mapping catalog entry,
1428 : * close connections depending on that entry immediately if current transaction
1429 : * has not used those connections yet. Otherwise, mark those connections as
1430 : * invalid and then make pgfdw_xact_callback() close them at the end of current
1431 : * transaction, since they cannot be closed in the midst of the transaction
1432 : * using them. Closed connections will be remade at the next opportunity if
1433 : * necessary.
1434 : *
1435 : * Although most cache invalidation callbacks blow away all the related stuff
1436 : * regardless of the given hashvalue, connections are expensive enough that
1437 : * it's worth trying to avoid that.
1438 : *
1439 : * NB: We could avoid unnecessary disconnection more strictly by examining
1440 : * individual option values, but it seems too much effort for the gain.
1441 : */
1442 : static void
1443 188 : pgfdw_inval_callback(Datum arg, SysCacheIdentifier cacheid, uint32 hashvalue)
1444 : {
1445 : HASH_SEQ_STATUS scan;
1446 : ConnCacheEntry *entry;
1447 :
1448 : Assert(cacheid == FOREIGNSERVEROID || cacheid == USERMAPPINGOID);
1449 :
1450 : /* ConnectionHash must exist already, if we're registered */
1451 188 : hash_seq_init(&scan, ConnectionHash);
1452 1222 : while ((entry = (ConnCacheEntry *) hash_seq_search(&scan)))
1453 : {
1454 : /* Ignore invalid entries */
1455 1034 : if (entry->conn == NULL)
1456 838 : continue;
1457 :
1458 : /* hashvalue == 0 means a cache reset, must clear all state */
1459 196 : if (hashvalue == 0 ||
1460 140 : (cacheid == FOREIGNSERVEROID &&
1461 196 : entry->server_hashvalue == hashvalue) ||
1462 56 : (cacheid == USERMAPPINGOID &&
1463 56 : entry->mapping_hashvalue == hashvalue))
1464 : {
1465 : /*
1466 : * Close the connection immediately if it's not used yet in this
1467 : * transaction. Otherwise mark it as invalid so that
1468 : * pgfdw_xact_callback() can close it at the end of this
1469 : * transaction.
1470 : */
1471 59 : if (entry->xact_depth == 0)
1472 : {
1473 56 : elog(DEBUG3, "discarding connection %p", entry->conn);
1474 56 : disconnect_pg_server(entry);
1475 : }
1476 : else
1477 3 : entry->invalidated = true;
1478 : }
1479 : }
1480 188 : }
1481 :
1482 : /*
1483 : * Raise an error if the given connection cache entry is marked as being
1484 : * in the middle of an xact state change. This should be called at which no
1485 : * such change is expected to be in progress; if one is found to be in
1486 : * progress, it means that we aborted in the middle of a previous state change
1487 : * and now don't know what the remote transaction state actually is.
1488 : * Such connections can't safely be further used. Re-establishing the
1489 : * connection would change the snapshot and roll back any writes already
1490 : * performed, so that's not an option, either. Thus, we must abort.
1491 : *
1492 : * Note: there might be open cursors that use the connection, so even if the
1493 : * connection cache entry is marked as such, we will retain it until abort
1494 : * cleanup of the main transaction, to ensure such open cursors can safely
1495 : * refer to the PGconn for the connection.
1496 : */
1497 : static void
1498 3024 : pgfdw_reject_incomplete_xact_state_change(ConnCacheEntry *entry)
1499 : {
1500 : ForeignServer *server;
1501 :
1502 : /* nothing to do for inactive entries and entries of sane state */
1503 3024 : if (entry->conn == NULL || !entry->changing_xact_state)
1504 3022 : return;
1505 :
1506 : /* find server name to be shown in the message below */
1507 2 : server = GetForeignServer(entry->serverid);
1508 :
1509 2 : ereport(ERROR,
1510 : (errcode(ERRCODE_CONNECTION_EXCEPTION),
1511 : errmsg("connection to server \"%s\" cannot be used due to abort cleanup failure",
1512 : server->servername)));
1513 : }
1514 :
1515 : /*
1516 : * Reset state to show we're out of a (sub)transaction.
1517 : */
1518 : static void
1519 1349 : pgfdw_reset_xact_state(ConnCacheEntry *entry, bool toplevel)
1520 : {
1521 1349 : if (toplevel)
1522 : {
1523 : /* Reset state to show we're out of a transaction */
1524 1328 : entry->xact_depth = 0;
1525 :
1526 : /* Reset xact r/o state */
1527 1328 : entry->xact_read_only = false;
1528 :
1529 : /*
1530 : * If the connection isn't in a good idle state, it is marked as
1531 : * invalid or keep_connections option of its server is disabled, then
1532 : * discard it to recover. Next GetConnection will open a new
1533 : * connection.
1534 : */
1535 2653 : if (PQstatus(entry->conn) != CONNECTION_OK ||
1536 1325 : PQtransactionStatus(entry->conn) != PQTRANS_IDLE ||
1537 1325 : entry->changing_xact_state ||
1538 1325 : entry->invalidated ||
1539 1323 : !entry->keep_connections)
1540 : {
1541 6 : elog(DEBUG3, "discarding connection %p", entry->conn);
1542 6 : disconnect_pg_server(entry);
1543 : }
1544 : }
1545 : else
1546 : {
1547 : /* Reset state to show we're out of a subtransaction */
1548 21 : entry->xact_depth--;
1549 :
1550 : /* If in read_only_level, reset xact r/o state */
1551 21 : if (entry->xact_depth + 1 == read_only_level)
1552 4 : entry->xact_read_only = false;
1553 : }
1554 1349 : }
1555 :
1556 : /*
1557 : * Cancel the currently-in-progress query (whose query text we do not have)
1558 : * and ignore the result. Returns true if we successfully cancel the query
1559 : * and discard any pending result, and false if not.
1560 : *
1561 : * It's not a huge problem if we throw an ERROR here, but if we get into error
1562 : * recursion trouble, we'll end up slamming the connection shut, which will
1563 : * necessitate failing the entire toplevel transaction even if subtransactions
1564 : * were used. Try to use WARNING where we can.
1565 : *
1566 : * XXX: if the query was one sent by fetch_more_data_begin(), we could get the
1567 : * query text from the pendingAreq saved in the per-connection state, then
1568 : * report the query using it.
1569 : */
1570 : static bool
1571 2 : pgfdw_cancel_query(PGconn *conn)
1572 : {
1573 2 : TimestampTz now = GetCurrentTimestamp();
1574 : TimestampTz endtime;
1575 : TimestampTz retrycanceltime;
1576 :
1577 : /*
1578 : * If it takes too long to cancel the query and discard the result, assume
1579 : * the connection is dead.
1580 : */
1581 2 : endtime = TimestampTzPlusMilliseconds(now, CONNECTION_CLEANUP_TIMEOUT);
1582 :
1583 : /*
1584 : * Also, lose patience and re-issue the cancel request after a little bit.
1585 : * (This serves to close some race conditions.)
1586 : */
1587 2 : retrycanceltime = TimestampTzPlusMilliseconds(now, RETRY_CANCEL_TIMEOUT);
1588 :
1589 2 : if (!pgfdw_cancel_query_begin(conn, endtime))
1590 0 : return false;
1591 2 : return pgfdw_cancel_query_end(conn, endtime, retrycanceltime, false);
1592 : }
1593 :
1594 : /*
1595 : * Submit a cancel request to the given connection, waiting only until
1596 : * the given time.
1597 : *
1598 : * We sleep interruptibly until we receive confirmation that the cancel
1599 : * request has been accepted, and if it is, return true; if the timeout
1600 : * lapses without that, or the request fails for whatever reason, return
1601 : * false.
1602 : */
1603 : static bool
1604 2 : pgfdw_cancel_query_begin(PGconn *conn, TimestampTz endtime)
1605 : {
1606 2 : const char *errormsg = libpqsrv_cancel(conn, endtime);
1607 :
1608 2 : if (errormsg != NULL)
1609 0 : ereport(WARNING,
1610 : errcode(ERRCODE_CONNECTION_FAILURE),
1611 : errmsg("could not send cancel request: %s", errormsg));
1612 :
1613 2 : return errormsg == NULL;
1614 : }
1615 :
1616 : static bool
1617 2 : pgfdw_cancel_query_end(PGconn *conn, TimestampTz endtime,
1618 : TimestampTz retrycanceltime, bool consume_input)
1619 : {
1620 : PGresult *result;
1621 : bool timed_out;
1622 :
1623 : /*
1624 : * If requested, consume whatever data is available from the socket. (Note
1625 : * that if all data is available, this allows pgfdw_get_cleanup_result to
1626 : * call PQgetResult without forcing the overhead of WaitLatchOrSocket,
1627 : * which would be large compared to the overhead of PQconsumeInput.)
1628 : */
1629 2 : if (consume_input && !PQconsumeInput(conn))
1630 : {
1631 0 : ereport(WARNING,
1632 : (errcode(ERRCODE_CONNECTION_FAILURE),
1633 : errmsg("could not get result of cancel request: %s",
1634 : pchomp(PQerrorMessage(conn)))));
1635 0 : return false;
1636 : }
1637 :
1638 : /* Get and discard the result of the query. */
1639 2 : if (pgfdw_get_cleanup_result(conn, endtime, retrycanceltime,
1640 : &result, &timed_out))
1641 : {
1642 0 : if (timed_out)
1643 0 : ereport(WARNING,
1644 : (errmsg("could not get result of cancel request due to timeout")));
1645 : else
1646 0 : ereport(WARNING,
1647 : (errcode(ERRCODE_CONNECTION_FAILURE),
1648 : errmsg("could not get result of cancel request: %s",
1649 : pchomp(PQerrorMessage(conn)))));
1650 :
1651 0 : return false;
1652 : }
1653 2 : PQclear(result);
1654 :
1655 2 : return true;
1656 : }
1657 :
1658 : /*
1659 : * Submit a query during (sub)abort cleanup and wait up to 30 seconds for the
1660 : * result. If the query is executed without error, the return value is true.
1661 : * If the query is executed successfully but returns an error, the return
1662 : * value is true if and only if ignore_errors is set. If the query can't be
1663 : * sent or times out, the return value is false.
1664 : *
1665 : * It's not a huge problem if we throw an ERROR here, but if we get into error
1666 : * recursion trouble, we'll end up slamming the connection shut, which will
1667 : * necessitate failing the entire toplevel transaction even if subtransactions
1668 : * were used. Try to use WARNING where we can.
1669 : */
1670 : static bool
1671 87 : pgfdw_exec_cleanup_query(PGconn *conn, const char *query, bool ignore_errors)
1672 : {
1673 : TimestampTz endtime;
1674 :
1675 : /*
1676 : * If it takes too long to execute a cleanup query, assume the connection
1677 : * is dead. It's fairly likely that this is why we aborted in the first
1678 : * place (e.g. statement timeout, user cancel), so the timeout shouldn't
1679 : * be too long.
1680 : */
1681 87 : endtime = TimestampTzPlusMilliseconds(GetCurrentTimestamp(),
1682 : CONNECTION_CLEANUP_TIMEOUT);
1683 :
1684 87 : if (!pgfdw_exec_cleanup_query_begin(conn, query))
1685 0 : return false;
1686 87 : return pgfdw_exec_cleanup_query_end(conn, query, endtime,
1687 : false, ignore_errors);
1688 : }
1689 :
1690 : static bool
1691 99 : pgfdw_exec_cleanup_query_begin(PGconn *conn, const char *query)
1692 : {
1693 : Assert(query != NULL);
1694 :
1695 : /*
1696 : * Submit a query. Since we don't use non-blocking mode, this also can
1697 : * block. But its risk is relatively small, so we ignore that for now.
1698 : */
1699 99 : if (!PQsendQuery(conn, query))
1700 : {
1701 0 : pgfdw_report(WARNING, NULL, conn, query);
1702 0 : return false;
1703 : }
1704 :
1705 99 : return true;
1706 : }
1707 :
1708 : static bool
1709 99 : pgfdw_exec_cleanup_query_end(PGconn *conn, const char *query,
1710 : TimestampTz endtime, bool consume_input,
1711 : bool ignore_errors)
1712 : {
1713 : PGresult *result;
1714 : bool timed_out;
1715 :
1716 : Assert(query != NULL);
1717 :
1718 : /*
1719 : * If requested, consume whatever data is available from the socket. (Note
1720 : * that if all data is available, this allows pgfdw_get_cleanup_result to
1721 : * call PQgetResult without forcing the overhead of WaitLatchOrSocket,
1722 : * which would be large compared to the overhead of PQconsumeInput.)
1723 : */
1724 99 : if (consume_input && !PQconsumeInput(conn))
1725 : {
1726 0 : pgfdw_report(WARNING, NULL, conn, query);
1727 0 : return false;
1728 : }
1729 :
1730 : /* Get the result of the query. */
1731 99 : if (pgfdw_get_cleanup_result(conn, endtime, endtime, &result, &timed_out))
1732 : {
1733 2 : if (timed_out)
1734 0 : ereport(WARNING,
1735 : (errmsg("could not get query result due to timeout"),
1736 : errcontext("remote SQL command: %s", query)));
1737 : else
1738 2 : pgfdw_report(WARNING, NULL, conn, query);
1739 :
1740 2 : return false;
1741 : }
1742 :
1743 : /* Issue a warning if not successful. */
1744 97 : if (PQresultStatus(result) != PGRES_COMMAND_OK)
1745 : {
1746 0 : pgfdw_report(WARNING, result, conn, query);
1747 0 : return ignore_errors;
1748 : }
1749 97 : PQclear(result);
1750 :
1751 97 : return true;
1752 : }
1753 :
1754 : /*
1755 : * Get, during abort cleanup, the result of a query that is in progress.
1756 : * This might be a query that is being interrupted by a cancel request or by
1757 : * transaction abort, or it might be a query that was initiated as part of
1758 : * transaction abort to get the remote side back to the appropriate state.
1759 : *
1760 : * endtime is the time at which we should give up and assume the remote side
1761 : * is dead. retrycanceltime is the time at which we should issue a fresh
1762 : * cancel request (pass the same value as endtime if this is not wanted).
1763 : *
1764 : * Returns true if the timeout expired or connection trouble occurred,
1765 : * false otherwise. Sets *result except in case of a true result.
1766 : * Sets *timed_out to true only when the timeout expired.
1767 : */
1768 : static bool
1769 101 : pgfdw_get_cleanup_result(PGconn *conn, TimestampTz endtime,
1770 : TimestampTz retrycanceltime,
1771 : PGresult **result,
1772 : bool *timed_out)
1773 : {
1774 101 : bool failed = false;
1775 101 : PGresult *last_res = NULL;
1776 101 : int canceldelta = RETRY_CANCEL_TIMEOUT * 2;
1777 :
1778 101 : *result = NULL;
1779 101 : *timed_out = false;
1780 : for (;;)
1781 113 : {
1782 : PGresult *res;
1783 :
1784 308 : while (PQisBusy(conn))
1785 : {
1786 : int wc;
1787 96 : TimestampTz now = GetCurrentTimestamp();
1788 : long cur_timeout;
1789 :
1790 : /* If timeout has expired, give up. */
1791 96 : if (now >= endtime)
1792 : {
1793 0 : *timed_out = true;
1794 0 : failed = true;
1795 0 : goto exit;
1796 : }
1797 :
1798 : /* If we need to re-issue the cancel request, do that. */
1799 96 : if (now >= retrycanceltime)
1800 : {
1801 : /* We ignore failure to issue the repeated request. */
1802 0 : (void) libpqsrv_cancel(conn, endtime);
1803 :
1804 : /* Recompute "now" in case that took measurable time. */
1805 0 : now = GetCurrentTimestamp();
1806 :
1807 : /* Adjust re-cancel timeout in increasing steps. */
1808 0 : retrycanceltime = TimestampTzPlusMilliseconds(now,
1809 : canceldelta);
1810 0 : canceldelta += canceldelta;
1811 : }
1812 :
1813 : /* If timeout has expired, give up, else get sleep time. */
1814 96 : cur_timeout = TimestampDifferenceMilliseconds(now,
1815 : Min(endtime,
1816 : retrycanceltime));
1817 96 : if (cur_timeout <= 0)
1818 : {
1819 0 : *timed_out = true;
1820 0 : failed = true;
1821 0 : goto exit;
1822 : }
1823 :
1824 : /* first time, allocate or get the custom wait event */
1825 96 : if (pgfdw_we_cleanup_result == 0)
1826 2 : pgfdw_we_cleanup_result = WaitEventExtensionNew("PostgresFdwCleanupResult");
1827 :
1828 : /* Sleep until there's something to do */
1829 96 : wc = WaitLatchOrSocket(MyLatch,
1830 : WL_LATCH_SET | WL_SOCKET_READABLE |
1831 : WL_TIMEOUT | WL_EXIT_ON_PM_DEATH,
1832 : PQsocket(conn),
1833 : cur_timeout, pgfdw_we_cleanup_result);
1834 96 : ResetLatch(MyLatch);
1835 :
1836 96 : CHECK_FOR_INTERRUPTS();
1837 :
1838 : /* Data available in socket? */
1839 96 : if (wc & WL_SOCKET_READABLE)
1840 : {
1841 96 : if (!PQconsumeInput(conn))
1842 : {
1843 : /* connection trouble */
1844 2 : failed = true;
1845 2 : goto exit;
1846 : }
1847 : }
1848 : }
1849 :
1850 212 : res = PQgetResult(conn);
1851 212 : if (res == NULL)
1852 99 : break; /* query is complete */
1853 :
1854 113 : PQclear(last_res);
1855 113 : last_res = res;
1856 : }
1857 101 : exit:
1858 101 : if (failed)
1859 2 : PQclear(last_res);
1860 : else
1861 99 : *result = last_res;
1862 101 : return failed;
1863 : }
1864 :
1865 : /*
1866 : * Abort remote transaction or subtransaction.
1867 : *
1868 : * "toplevel" should be set to true if toplevel (main) transaction is
1869 : * rollbacked, false otherwise.
1870 : *
1871 : * Set entry->changing_xact_state to false on success, true on failure.
1872 : */
1873 : static void
1874 65 : pgfdw_abort_cleanup(ConnCacheEntry *entry, bool toplevel)
1875 : {
1876 : char sql[100];
1877 :
1878 : /*
1879 : * Don't try to clean up the connection if we're already in error
1880 : * recursion trouble.
1881 : */
1882 65 : if (in_error_recursion_trouble())
1883 0 : entry->changing_xact_state = true;
1884 :
1885 : /*
1886 : * If connection is already unsalvageable, don't touch it further.
1887 : */
1888 65 : if (entry->changing_xact_state)
1889 5 : return;
1890 :
1891 : /*
1892 : * Mark this connection as in the process of changing transaction state.
1893 : */
1894 62 : entry->changing_xact_state = true;
1895 :
1896 : /* Assume we might have lost track of prepared statements */
1897 62 : entry->have_error = true;
1898 :
1899 : /*
1900 : * If a command has been submitted to the remote server by using an
1901 : * asynchronous execution function, the command might not have yet
1902 : * completed. Check to see if a command is still being processed by the
1903 : * remote server, and if so, request cancellation of the command.
1904 : */
1905 62 : if (PQtransactionStatus(entry->conn) == PQTRANS_ACTIVE &&
1906 2 : !pgfdw_cancel_query(entry->conn))
1907 0 : return; /* Unable to cancel running query */
1908 :
1909 62 : CONSTRUCT_ABORT_COMMAND(sql, entry, toplevel);
1910 62 : if (!pgfdw_exec_cleanup_query(entry->conn, sql, false))
1911 2 : return; /* Unable to abort remote (sub)transaction */
1912 :
1913 60 : if (toplevel)
1914 : {
1915 52 : if (entry->have_prep_stmt && entry->have_error &&
1916 25 : !pgfdw_exec_cleanup_query(entry->conn,
1917 : "DEALLOCATE ALL",
1918 : true))
1919 0 : return; /* Trouble clearing prepared statements */
1920 :
1921 52 : entry->have_prep_stmt = false;
1922 52 : entry->have_error = false;
1923 : }
1924 :
1925 : /*
1926 : * If pendingAreq of the per-connection state is not NULL, it means that
1927 : * an asynchronous fetch begun by fetch_more_data_begin() was not done
1928 : * successfully and thus the per-connection state was not reset in
1929 : * fetch_more_data(); in that case reset the per-connection state here.
1930 : */
1931 60 : if (entry->state.pendingAreq)
1932 1 : memset(&entry->state, 0, sizeof(entry->state));
1933 :
1934 : /* Disarm changing_xact_state if it all worked */
1935 60 : entry->changing_xact_state = false;
1936 : }
1937 :
1938 : /*
1939 : * Like pgfdw_abort_cleanup, submit an abort command or cancel request, but
1940 : * don't wait for the result.
1941 : *
1942 : * Returns true if the abort command or cancel request is successfully issued,
1943 : * false otherwise. If the abort command is successfully issued, the given
1944 : * connection cache entry is appended to *pending_entries. Otherwise, if the
1945 : * cancel request is successfully issued, it is appended to *cancel_requested.
1946 : */
1947 : static bool
1948 8 : pgfdw_abort_cleanup_begin(ConnCacheEntry *entry, bool toplevel,
1949 : List **pending_entries, List **cancel_requested)
1950 : {
1951 : /*
1952 : * Don't try to clean up the connection if we're already in error
1953 : * recursion trouble.
1954 : */
1955 8 : if (in_error_recursion_trouble())
1956 0 : entry->changing_xact_state = true;
1957 :
1958 : /*
1959 : * If connection is already unsalvageable, don't touch it further.
1960 : */
1961 8 : if (entry->changing_xact_state)
1962 0 : return false;
1963 :
1964 : /*
1965 : * Mark this connection as in the process of changing transaction state.
1966 : */
1967 8 : entry->changing_xact_state = true;
1968 :
1969 : /* Assume we might have lost track of prepared statements */
1970 8 : entry->have_error = true;
1971 :
1972 : /*
1973 : * If a command has been submitted to the remote server by using an
1974 : * asynchronous execution function, the command might not have yet
1975 : * completed. Check to see if a command is still being processed by the
1976 : * remote server, and if so, request cancellation of the command.
1977 : */
1978 8 : if (PQtransactionStatus(entry->conn) == PQTRANS_ACTIVE)
1979 : {
1980 : TimestampTz endtime;
1981 :
1982 0 : endtime = TimestampTzPlusMilliseconds(GetCurrentTimestamp(),
1983 : CONNECTION_CLEANUP_TIMEOUT);
1984 0 : if (!pgfdw_cancel_query_begin(entry->conn, endtime))
1985 0 : return false; /* Unable to cancel running query */
1986 0 : *cancel_requested = lappend(*cancel_requested, entry);
1987 : }
1988 : else
1989 : {
1990 : char sql[100];
1991 :
1992 8 : CONSTRUCT_ABORT_COMMAND(sql, entry, toplevel);
1993 8 : if (!pgfdw_exec_cleanup_query_begin(entry->conn, sql))
1994 0 : return false; /* Unable to abort remote transaction */
1995 8 : *pending_entries = lappend(*pending_entries, entry);
1996 : }
1997 :
1998 8 : return true;
1999 : }
2000 :
2001 : /*
2002 : * Finish pre-commit cleanup of connections on each of which we've sent a
2003 : * COMMIT command to the remote server.
2004 : */
2005 : static void
2006 13 : pgfdw_finish_pre_commit_cleanup(List *pending_entries)
2007 : {
2008 : ConnCacheEntry *entry;
2009 13 : List *pending_deallocs = NIL;
2010 : ListCell *lc;
2011 :
2012 : Assert(pending_entries);
2013 :
2014 : /*
2015 : * Get the result of the COMMIT command for each of the pending entries
2016 : */
2017 29 : foreach(lc, pending_entries)
2018 : {
2019 16 : entry = (ConnCacheEntry *) lfirst(lc);
2020 :
2021 : Assert(entry->changing_xact_state);
2022 :
2023 : /*
2024 : * We might already have received the result on the socket, so pass
2025 : * consume_input=true to try to consume it first
2026 : */
2027 16 : do_sql_command_end(entry->conn, "COMMIT TRANSACTION", true);
2028 16 : entry->changing_xact_state = false;
2029 :
2030 : /* Do a DEALLOCATE ALL in parallel if needed */
2031 16 : if (entry->have_prep_stmt && entry->have_error)
2032 : {
2033 : /* Ignore errors (see notes in pgfdw_xact_callback) */
2034 2 : if (PQsendQuery(entry->conn, "DEALLOCATE ALL"))
2035 : {
2036 2 : pending_deallocs = lappend(pending_deallocs, entry);
2037 2 : continue;
2038 : }
2039 : }
2040 14 : entry->have_prep_stmt = false;
2041 14 : entry->have_error = false;
2042 :
2043 14 : pgfdw_reset_xact_state(entry, true);
2044 : }
2045 :
2046 : /* No further work if no pending entries */
2047 13 : if (!pending_deallocs)
2048 12 : return;
2049 :
2050 : /*
2051 : * Get the result of the DEALLOCATE command for each of the pending
2052 : * entries
2053 : */
2054 3 : foreach(lc, pending_deallocs)
2055 : {
2056 : PGresult *res;
2057 :
2058 2 : entry = (ConnCacheEntry *) lfirst(lc);
2059 :
2060 : /* Ignore errors (see notes in pgfdw_xact_callback) */
2061 4 : while ((res = PQgetResult(entry->conn)) != NULL)
2062 : {
2063 2 : PQclear(res);
2064 : /* Stop if the connection is lost (else we'll loop infinitely) */
2065 2 : if (PQstatus(entry->conn) == CONNECTION_BAD)
2066 0 : break;
2067 : }
2068 2 : entry->have_prep_stmt = false;
2069 2 : entry->have_error = false;
2070 :
2071 2 : pgfdw_reset_xact_state(entry, true);
2072 : }
2073 : }
2074 :
2075 : /*
2076 : * Finish pre-subcommit cleanup of connections on each of which we've sent a
2077 : * RELEASE command to the remote server.
2078 : */
2079 : static void
2080 1 : pgfdw_finish_pre_subcommit_cleanup(List *pending_entries, int curlevel)
2081 : {
2082 : ConnCacheEntry *entry;
2083 : char sql[100];
2084 : ListCell *lc;
2085 :
2086 : Assert(pending_entries);
2087 :
2088 : /*
2089 : * Get the result of the RELEASE command for each of the pending entries
2090 : */
2091 1 : snprintf(sql, sizeof(sql), "RELEASE SAVEPOINT s%d", curlevel);
2092 3 : foreach(lc, pending_entries)
2093 : {
2094 2 : entry = (ConnCacheEntry *) lfirst(lc);
2095 :
2096 : Assert(entry->changing_xact_state);
2097 :
2098 : /*
2099 : * We might already have received the result on the socket, so pass
2100 : * consume_input=true to try to consume it first
2101 : */
2102 2 : do_sql_command_end(entry->conn, sql, true);
2103 2 : entry->changing_xact_state = false;
2104 :
2105 2 : pgfdw_reset_xact_state(entry, false);
2106 : }
2107 1 : }
2108 :
2109 : /*
2110 : * Finish abort cleanup of connections on each of which we've sent an abort
2111 : * command or cancel request to the remote server.
2112 : */
2113 : static void
2114 4 : pgfdw_finish_abort_cleanup(List *pending_entries, List *cancel_requested,
2115 : bool toplevel)
2116 : {
2117 4 : List *pending_deallocs = NIL;
2118 : ListCell *lc;
2119 :
2120 : /*
2121 : * For each of the pending cancel requests (if any), get and discard the
2122 : * result of the query, and submit an abort command to the remote server.
2123 : */
2124 4 : if (cancel_requested)
2125 : {
2126 0 : foreach(lc, cancel_requested)
2127 : {
2128 0 : ConnCacheEntry *entry = (ConnCacheEntry *) lfirst(lc);
2129 0 : TimestampTz now = GetCurrentTimestamp();
2130 : TimestampTz endtime;
2131 : TimestampTz retrycanceltime;
2132 : char sql[100];
2133 :
2134 : Assert(entry->changing_xact_state);
2135 :
2136 : /*
2137 : * Set end time. You might think we should do this before issuing
2138 : * cancel request like in normal mode, but that is problematic,
2139 : * because if, for example, it took longer than 30 seconds to
2140 : * process the first few entries in the cancel_requested list, it
2141 : * would cause a timeout error when processing each of the
2142 : * remaining entries in the list, leading to slamming that entry's
2143 : * connection shut.
2144 : */
2145 0 : endtime = TimestampTzPlusMilliseconds(now,
2146 : CONNECTION_CLEANUP_TIMEOUT);
2147 0 : retrycanceltime = TimestampTzPlusMilliseconds(now,
2148 : RETRY_CANCEL_TIMEOUT);
2149 :
2150 0 : if (!pgfdw_cancel_query_end(entry->conn, endtime,
2151 : retrycanceltime, true))
2152 : {
2153 : /* Unable to cancel running query */
2154 0 : pgfdw_reset_xact_state(entry, toplevel);
2155 0 : continue;
2156 : }
2157 :
2158 : /* Send an abort command in parallel if needed */
2159 0 : CONSTRUCT_ABORT_COMMAND(sql, entry, toplevel);
2160 0 : if (!pgfdw_exec_cleanup_query_begin(entry->conn, sql))
2161 : {
2162 : /* Unable to abort remote (sub)transaction */
2163 0 : pgfdw_reset_xact_state(entry, toplevel);
2164 : }
2165 : else
2166 0 : pending_entries = lappend(pending_entries, entry);
2167 : }
2168 : }
2169 :
2170 : /* No further work if no pending entries */
2171 4 : if (!pending_entries)
2172 0 : return;
2173 :
2174 : /*
2175 : * Get the result of the abort command for each of the pending entries
2176 : */
2177 12 : foreach(lc, pending_entries)
2178 : {
2179 8 : ConnCacheEntry *entry = (ConnCacheEntry *) lfirst(lc);
2180 : TimestampTz endtime;
2181 : char sql[100];
2182 :
2183 : Assert(entry->changing_xact_state);
2184 :
2185 : /*
2186 : * Set end time. We do this now, not before issuing the command like
2187 : * in normal mode, for the same reason as for the cancel_requested
2188 : * entries.
2189 : */
2190 8 : endtime = TimestampTzPlusMilliseconds(GetCurrentTimestamp(),
2191 : CONNECTION_CLEANUP_TIMEOUT);
2192 :
2193 8 : CONSTRUCT_ABORT_COMMAND(sql, entry, toplevel);
2194 8 : if (!pgfdw_exec_cleanup_query_end(entry->conn, sql, endtime,
2195 : true, false))
2196 : {
2197 : /* Unable to abort remote (sub)transaction */
2198 0 : pgfdw_reset_xact_state(entry, toplevel);
2199 4 : continue;
2200 : }
2201 :
2202 8 : if (toplevel)
2203 : {
2204 : /* Do a DEALLOCATE ALL in parallel if needed */
2205 4 : if (entry->have_prep_stmt && entry->have_error)
2206 : {
2207 4 : if (!pgfdw_exec_cleanup_query_begin(entry->conn,
2208 : "DEALLOCATE ALL"))
2209 : {
2210 : /* Trouble clearing prepared statements */
2211 0 : pgfdw_reset_xact_state(entry, toplevel);
2212 : }
2213 : else
2214 4 : pending_deallocs = lappend(pending_deallocs, entry);
2215 4 : continue;
2216 : }
2217 0 : entry->have_prep_stmt = false;
2218 0 : entry->have_error = false;
2219 : }
2220 :
2221 : /* Reset the per-connection state if needed */
2222 4 : if (entry->state.pendingAreq)
2223 0 : memset(&entry->state, 0, sizeof(entry->state));
2224 :
2225 : /* We're done with this entry; unset the changing_xact_state flag */
2226 4 : entry->changing_xact_state = false;
2227 4 : pgfdw_reset_xact_state(entry, toplevel);
2228 : }
2229 :
2230 : /* No further work if no pending entries */
2231 4 : if (!pending_deallocs)
2232 2 : return;
2233 : Assert(toplevel);
2234 :
2235 : /*
2236 : * Get the result of the DEALLOCATE command for each of the pending
2237 : * entries
2238 : */
2239 6 : foreach(lc, pending_deallocs)
2240 : {
2241 4 : ConnCacheEntry *entry = (ConnCacheEntry *) lfirst(lc);
2242 : TimestampTz endtime;
2243 :
2244 : Assert(entry->changing_xact_state);
2245 : Assert(entry->have_prep_stmt);
2246 : Assert(entry->have_error);
2247 :
2248 : /*
2249 : * Set end time. We do this now, not before issuing the command like
2250 : * in normal mode, for the same reason as for the cancel_requested
2251 : * entries.
2252 : */
2253 4 : endtime = TimestampTzPlusMilliseconds(GetCurrentTimestamp(),
2254 : CONNECTION_CLEANUP_TIMEOUT);
2255 :
2256 4 : if (!pgfdw_exec_cleanup_query_end(entry->conn, "DEALLOCATE ALL",
2257 : endtime, true, true))
2258 : {
2259 : /* Trouble clearing prepared statements */
2260 0 : pgfdw_reset_xact_state(entry, toplevel);
2261 0 : continue;
2262 : }
2263 4 : entry->have_prep_stmt = false;
2264 4 : entry->have_error = false;
2265 :
2266 : /* Reset the per-connection state if needed */
2267 4 : if (entry->state.pendingAreq)
2268 0 : memset(&entry->state, 0, sizeof(entry->state));
2269 :
2270 : /* We're done with this entry; unset the changing_xact_state flag */
2271 4 : entry->changing_xact_state = false;
2272 4 : pgfdw_reset_xact_state(entry, toplevel);
2273 : }
2274 : }
2275 :
2276 : /* Number of output arguments (columns) for various API versions */
2277 : #define POSTGRES_FDW_GET_CONNECTIONS_COLS_V1_1 2
2278 : #define POSTGRES_FDW_GET_CONNECTIONS_COLS_V1_2 6
2279 : #define POSTGRES_FDW_GET_CONNECTIONS_COLS 6 /* maximum of above */
2280 :
2281 : /*
2282 : * Internal function used by postgres_fdw_get_connections variants.
2283 : *
2284 : * For API version 1.1, this function takes no input parameter and
2285 : * returns a set of records with the following values:
2286 : *
2287 : * - server_name - server name of active connection. In case the foreign server
2288 : * is dropped but still the connection is active, then the server name will
2289 : * be NULL in output.
2290 : * - valid - true/false representing whether the connection is valid or not.
2291 : * Note that connections can become invalid in pgfdw_inval_callback.
2292 : *
2293 : * For API version 1.2 and later, this function takes an input parameter
2294 : * to check a connection status and returns the following
2295 : * additional values along with the four values from version 1.1:
2296 : *
2297 : * - user_name - the local user name of the active connection. In case the
2298 : * user mapping is dropped but the connection is still active, then the
2299 : * user name will be NULL in the output.
2300 : * - used_in_xact - true if the connection is used in the current transaction.
2301 : * - closed - true if the connection is closed.
2302 : * - remote_backend_pid - process ID of the remote backend, on the foreign
2303 : * server, handling the connection.
2304 : *
2305 : * No records are returned when there are no cached connections at all.
2306 : */
2307 : static void
2308 13 : postgres_fdw_get_connections_internal(FunctionCallInfo fcinfo,
2309 : enum pgfdwVersion api_version)
2310 : {
2311 13 : ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
2312 : HASH_SEQ_STATUS scan;
2313 : ConnCacheEntry *entry;
2314 :
2315 13 : InitMaterializedSRF(fcinfo, 0);
2316 :
2317 : /* If cache doesn't exist, we return no records */
2318 13 : if (!ConnectionHash)
2319 0 : return;
2320 :
2321 : /* Check we have the expected number of output arguments */
2322 13 : switch (rsinfo->setDesc->natts)
2323 : {
2324 0 : case POSTGRES_FDW_GET_CONNECTIONS_COLS_V1_1:
2325 0 : if (api_version != PGFDW_V1_1)
2326 0 : elog(ERROR, "incorrect number of output arguments");
2327 0 : break;
2328 13 : case POSTGRES_FDW_GET_CONNECTIONS_COLS_V1_2:
2329 13 : if (api_version != PGFDW_V1_2)
2330 0 : elog(ERROR, "incorrect number of output arguments");
2331 13 : break;
2332 0 : default:
2333 0 : elog(ERROR, "incorrect number of output arguments");
2334 : }
2335 :
2336 13 : hash_seq_init(&scan, ConnectionHash);
2337 113 : while ((entry = (ConnCacheEntry *) hash_seq_search(&scan)))
2338 : {
2339 : ForeignServer *server;
2340 100 : Datum values[POSTGRES_FDW_GET_CONNECTIONS_COLS] = {0};
2341 100 : bool nulls[POSTGRES_FDW_GET_CONNECTIONS_COLS] = {0};
2342 100 : int i = 0;
2343 :
2344 : /* We only look for open remote connections */
2345 100 : if (!entry->conn)
2346 87 : continue;
2347 :
2348 13 : server = GetForeignServerExtended(entry->serverid, FSV_MISSING_OK);
2349 :
2350 : /*
2351 : * The foreign server may have been dropped in current explicit
2352 : * transaction. It is not possible to drop the server from another
2353 : * session when the connection associated with it is in use in the
2354 : * current transaction, if tried so, the drop query in another session
2355 : * blocks until the current transaction finishes.
2356 : *
2357 : * Even though the server is dropped in the current transaction, the
2358 : * cache can still have associated active connection entry, say we
2359 : * call such connections dangling. Since we can not fetch the server
2360 : * name from system catalogs for dangling connections, instead we show
2361 : * NULL value for server name in output.
2362 : *
2363 : * We could have done better by storing the server name in the cache
2364 : * entry instead of server oid so that it could be used in the output.
2365 : * But the server name in each cache entry requires 64 bytes of
2366 : * memory, which is huge, when there are many cached connections and
2367 : * the use case i.e. dropping the foreign server within the explicit
2368 : * current transaction seems rare. So, we chose to show NULL value for
2369 : * server name in output.
2370 : *
2371 : * Such dangling connections get closed either in next use or at the
2372 : * end of current explicit transaction in pgfdw_xact_callback.
2373 : */
2374 13 : if (!server)
2375 : {
2376 : /*
2377 : * If the server has been dropped in the current explicit
2378 : * transaction, then this entry would have been invalidated in
2379 : * pgfdw_inval_callback at the end of drop server command. Note
2380 : * that this connection would not have been closed in
2381 : * pgfdw_inval_callback because it is still being used in the
2382 : * current explicit transaction. So, assert that here.
2383 : */
2384 : Assert(entry->conn && entry->xact_depth > 0 && entry->invalidated);
2385 :
2386 : /* Show null, if no server name was found */
2387 1 : nulls[i++] = true;
2388 : }
2389 : else
2390 12 : values[i++] = CStringGetTextDatum(server->servername);
2391 :
2392 13 : if (api_version >= PGFDW_V1_2)
2393 : {
2394 : HeapTuple tp;
2395 :
2396 : /* Use the system cache to obtain the user mapping */
2397 13 : tp = SearchSysCache1(USERMAPPINGOID, ObjectIdGetDatum(entry->key));
2398 :
2399 : /*
2400 : * Just like in the foreign server case, user mappings can also be
2401 : * dropped in the current explicit transaction. Therefore, the
2402 : * similar check as in the server case is required.
2403 : */
2404 13 : if (!HeapTupleIsValid(tp))
2405 : {
2406 : /*
2407 : * If we reach here, this entry must have been invalidated in
2408 : * pgfdw_inval_callback, same as in the server case.
2409 : */
2410 : Assert(entry->conn && entry->xact_depth > 0 &&
2411 : entry->invalidated);
2412 :
2413 1 : nulls[i++] = true;
2414 : }
2415 : else
2416 : {
2417 : Oid userid;
2418 :
2419 12 : userid = ((Form_pg_user_mapping) GETSTRUCT(tp))->umuser;
2420 12 : values[i++] = CStringGetTextDatum(MappingUserName(userid));
2421 12 : ReleaseSysCache(tp);
2422 : }
2423 : }
2424 :
2425 13 : values[i++] = BoolGetDatum(!entry->invalidated);
2426 :
2427 13 : if (api_version >= PGFDW_V1_2)
2428 : {
2429 13 : bool check_conn = PG_GETARG_BOOL(0);
2430 :
2431 : /* Is this connection used in the current transaction? */
2432 13 : values[i++] = BoolGetDatum(entry->xact_depth > 0);
2433 :
2434 : /*
2435 : * If a connection status check is requested and supported, return
2436 : * whether the connection is closed. Otherwise, return NULL.
2437 : */
2438 13 : if (check_conn && pgfdw_conn_checkable())
2439 2 : values[i++] = BoolGetDatum(pgfdw_conn_check(entry->conn) != 0);
2440 : else
2441 11 : nulls[i++] = true;
2442 :
2443 : /* Return process ID of remote backend */
2444 13 : values[i++] = Int32GetDatum(PQbackendPID(entry->conn));
2445 : }
2446 :
2447 13 : tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
2448 : }
2449 : }
2450 :
2451 : /*
2452 : * Values in connection strings must be enclosed in single quotes. Single
2453 : * quotes and backslashes must be escaped with backslash. NB: these rules are
2454 : * different from the rules for escaping a SQL literal.
2455 : */
2456 : static void
2457 65 : appendEscapedValue(StringInfo str, const char *val)
2458 : {
2459 65 : appendStringInfoChar(str, '\'');
2460 548 : for (int i = 0; val[i] != '\0'; i++)
2461 : {
2462 483 : if (val[i] == '\\' || val[i] == '\'')
2463 0 : appendStringInfoChar(str, '\\');
2464 483 : appendStringInfoChar(str, val[i]);
2465 : }
2466 65 : appendStringInfoChar(str, '\'');
2467 65 : }
2468 :
2469 : Datum
2470 9 : postgres_fdw_connection(PG_FUNCTION_ARGS)
2471 : {
2472 9 : Oid userid = PG_GETARG_OID(0);
2473 9 : Oid serverid = PG_GETARG_OID(1);
2474 9 : ForeignServer *server = GetForeignServer(serverid);
2475 9 : UserMapping *user = GetUserMapping(userid, serverid);
2476 : StringInfoData str;
2477 : const char **keywords;
2478 : const char **values;
2479 : char *appname;
2480 9 : char *sep = "";
2481 :
2482 9 : construct_connection_params(server, user, &keywords, &values, &appname);
2483 :
2484 9 : initStringInfo(&str);
2485 74 : for (int i = 0; keywords[i] != NULL; i++)
2486 : {
2487 65 : if (values[i] == NULL)
2488 0 : continue;
2489 65 : appendStringInfo(&str, "%s%s = ", sep, keywords[i]);
2490 65 : appendEscapedValue(&str, values[i]);
2491 65 : sep = " ";
2492 : }
2493 :
2494 9 : if (appname != NULL)
2495 1 : pfree(appname);
2496 9 : pfree(keywords);
2497 9 : pfree(values);
2498 9 : PG_RETURN_TEXT_P(cstring_to_text(str.data));
2499 : }
2500 :
2501 : /*
2502 : * List active foreign server connections.
2503 : *
2504 : * The SQL API of this function has changed multiple times, and will likely
2505 : * do so again in future. To support the case where a newer version of this
2506 : * loadable module is being used with an old SQL declaration of the function,
2507 : * we continue to support the older API versions.
2508 : */
2509 : Datum
2510 13 : postgres_fdw_get_connections_1_2(PG_FUNCTION_ARGS)
2511 : {
2512 13 : postgres_fdw_get_connections_internal(fcinfo, PGFDW_V1_2);
2513 :
2514 13 : PG_RETURN_VOID();
2515 : }
2516 :
2517 : Datum
2518 0 : postgres_fdw_get_connections(PG_FUNCTION_ARGS)
2519 : {
2520 0 : postgres_fdw_get_connections_internal(fcinfo, PGFDW_V1_1);
2521 :
2522 0 : PG_RETURN_VOID();
2523 : }
2524 :
2525 : /*
2526 : * Disconnect the specified cached connections.
2527 : *
2528 : * This function discards the open connections that are established by
2529 : * postgres_fdw from the local session to the foreign server with
2530 : * the given name. Note that there can be multiple connections to
2531 : * the given server using different user mappings. If the connections
2532 : * are used in the current local transaction, they are not disconnected
2533 : * and warning messages are reported. This function returns true
2534 : * if it disconnects at least one connection, otherwise false. If no
2535 : * foreign server with the given name is found, an error is reported.
2536 : */
2537 : Datum
2538 4 : postgres_fdw_disconnect(PG_FUNCTION_ARGS)
2539 : {
2540 : ForeignServer *server;
2541 : char *servername;
2542 :
2543 4 : servername = text_to_cstring(PG_GETARG_TEXT_PP(0));
2544 4 : server = GetForeignServerByName(servername, false);
2545 :
2546 3 : PG_RETURN_BOOL(disconnect_cached_connections(server->serverid));
2547 : }
2548 :
2549 : /*
2550 : * Disconnect all the cached connections.
2551 : *
2552 : * This function discards all the open connections that are established by
2553 : * postgres_fdw from the local session to the foreign servers.
2554 : * If the connections are used in the current local transaction, they are
2555 : * not disconnected and warning messages are reported. This function
2556 : * returns true if it disconnects at least one connection, otherwise false.
2557 : */
2558 : Datum
2559 5 : postgres_fdw_disconnect_all(PG_FUNCTION_ARGS)
2560 : {
2561 5 : PG_RETURN_BOOL(disconnect_cached_connections(InvalidOid));
2562 : }
2563 :
2564 : /*
2565 : * Workhorse to disconnect cached connections.
2566 : *
2567 : * This function scans all the connection cache entries and disconnects
2568 : * the open connections whose foreign server OID matches with
2569 : * the specified one. If InvalidOid is specified, it disconnects all
2570 : * the cached connections.
2571 : *
2572 : * This function emits a warning for each connection that's used in
2573 : * the current transaction and doesn't close it. It returns true if
2574 : * it disconnects at least one connection, otherwise false.
2575 : *
2576 : * Note that this function disconnects even the connections that are
2577 : * established by other users in the same local session using different
2578 : * user mappings. This leads even non-superuser to be able to close
2579 : * the connections established by superusers in the same local session.
2580 : *
2581 : * XXX As of now we don't see any security risk doing this. But we should
2582 : * set some restrictions on that, for example, prevent non-superuser
2583 : * from closing the connections established by superusers even
2584 : * in the same session?
2585 : */
2586 : static bool
2587 8 : disconnect_cached_connections(Oid serverid)
2588 : {
2589 : HASH_SEQ_STATUS scan;
2590 : ConnCacheEntry *entry;
2591 8 : bool all = !OidIsValid(serverid);
2592 8 : bool result = false;
2593 :
2594 : /*
2595 : * Connection cache hashtable has not been initialized yet in this
2596 : * session, so return false.
2597 : */
2598 8 : if (!ConnectionHash)
2599 0 : return false;
2600 :
2601 8 : hash_seq_init(&scan, ConnectionHash);
2602 67 : while ((entry = (ConnCacheEntry *) hash_seq_search(&scan)))
2603 : {
2604 : /* Ignore cache entry if no open connection right now. */
2605 59 : if (!entry->conn)
2606 47 : continue;
2607 :
2608 12 : if (all || entry->serverid == serverid)
2609 : {
2610 : /*
2611 : * Emit a warning because the connection to close is used in the
2612 : * current transaction and cannot be disconnected right now.
2613 : */
2614 9 : if (entry->xact_depth > 0)
2615 : {
2616 : ForeignServer *server;
2617 :
2618 3 : server = GetForeignServerExtended(entry->serverid,
2619 : FSV_MISSING_OK);
2620 :
2621 3 : if (!server)
2622 : {
2623 : /*
2624 : * If the foreign server was dropped while its connection
2625 : * was used in the current transaction, the connection
2626 : * must have been marked as invalid by
2627 : * pgfdw_inval_callback at the end of DROP SERVER command.
2628 : */
2629 : Assert(entry->invalidated);
2630 :
2631 0 : ereport(WARNING,
2632 : (errmsg("cannot close dropped server connection because it is still in use")));
2633 : }
2634 : else
2635 3 : ereport(WARNING,
2636 : (errmsg("cannot close connection for server \"%s\" because it is still in use",
2637 : server->servername)));
2638 : }
2639 : else
2640 : {
2641 6 : elog(DEBUG3, "discarding connection %p", entry->conn);
2642 6 : disconnect_pg_server(entry);
2643 6 : result = true;
2644 : }
2645 : }
2646 : }
2647 :
2648 8 : return result;
2649 : }
2650 :
2651 : /*
2652 : * Check if the remote server closed the connection.
2653 : *
2654 : * Returns 1 if the connection is closed, -1 if an error occurred,
2655 : * and 0 if it's not closed or if the connection check is unavailable
2656 : * on this platform.
2657 : */
2658 : static int
2659 2 : pgfdw_conn_check(PGconn *conn)
2660 : {
2661 2 : int sock = PQsocket(conn);
2662 :
2663 2 : if (PQstatus(conn) != CONNECTION_OK || sock == -1)
2664 0 : return -1;
2665 :
2666 : #if (defined(HAVE_POLL) && defined(POLLRDHUP))
2667 : {
2668 : struct pollfd input_fd;
2669 : int result;
2670 :
2671 2 : input_fd.fd = sock;
2672 2 : input_fd.events = POLLRDHUP;
2673 2 : input_fd.revents = 0;
2674 :
2675 : do
2676 2 : result = poll(&input_fd, 1, 0);
2677 2 : while (result < 0 && errno == EINTR);
2678 :
2679 2 : if (result < 0)
2680 0 : return -1;
2681 :
2682 2 : return (input_fd.revents &
2683 2 : (POLLRDHUP | POLLHUP | POLLERR | POLLNVAL)) ? 1 : 0;
2684 : }
2685 : #else
2686 : return 0;
2687 : #endif
2688 : }
2689 :
2690 : /*
2691 : * Check if connection status checking is available on this platform.
2692 : *
2693 : * Returns true if available, false otherwise.
2694 : */
2695 : static bool
2696 2 : pgfdw_conn_checkable(void)
2697 : {
2698 : #if (defined(HAVE_POLL) && defined(POLLRDHUP))
2699 2 : return true;
2700 : #else
2701 : return false;
2702 : #endif
2703 : }
2704 :
2705 : /*
2706 : * Ensure that require_auth and SCRAM keys are correctly set on values. SCRAM
2707 : * keys used to pass-through are coming from the initial connection from the
2708 : * client with the server.
2709 : *
2710 : * All required SCRAM options are set by postgres_fdw, so we just need to
2711 : * ensure that these options are not overwritten by the user.
2712 : */
2713 : static bool
2714 11 : pgfdw_has_required_scram_options(const char **keywords, const char **values)
2715 : {
2716 11 : bool has_scram_server_key = false;
2717 11 : bool has_scram_client_key = false;
2718 11 : bool has_require_auth = false;
2719 11 : bool has_scram_keys = false;
2720 :
2721 : /*
2722 : * Continue iterating even if we found the keys that we need to validate
2723 : * to make sure that there is no other declaration of these keys that can
2724 : * overwrite the first.
2725 : */
2726 107 : for (int i = 0; keywords[i] != NULL; i++)
2727 : {
2728 96 : if (strcmp(keywords[i], "scram_client_key") == 0)
2729 : {
2730 10 : if (values[i] != NULL && values[i][0] != '\0')
2731 10 : has_scram_client_key = true;
2732 : else
2733 0 : has_scram_client_key = false;
2734 : }
2735 :
2736 96 : if (strcmp(keywords[i], "scram_server_key") == 0)
2737 : {
2738 10 : if (values[i] != NULL && values[i][0] != '\0')
2739 10 : has_scram_server_key = true;
2740 : else
2741 0 : has_scram_server_key = false;
2742 : }
2743 :
2744 96 : if (strcmp(keywords[i], "require_auth") == 0)
2745 : {
2746 10 : if (values[i] != NULL && strcmp(values[i], "scram-sha-256") == 0)
2747 10 : has_require_auth = true;
2748 : else
2749 0 : has_require_auth = false;
2750 : }
2751 : }
2752 :
2753 11 : has_scram_keys = has_scram_client_key && has_scram_server_key && MyProcPort != NULL && MyProcPort->has_scram_keys;
2754 :
2755 11 : return (has_scram_keys && has_require_auth);
2756 : }
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