Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * connection.c
4 : * Connection management functions for postgres_fdw
5 : *
6 : * Portions Copyright (c) 2012-2025, 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/xact.h"
20 : #include "catalog/pg_user_mapping.h"
21 : #include "commands/defrem.h"
22 : #include "common/base64.h"
23 : #include "funcapi.h"
24 : #include "libpq/libpq-be.h"
25 : #include "libpq/libpq-be-fe-helpers.h"
26 : #include "mb/pg_wchar.h"
27 : #include "miscadmin.h"
28 : #include "pgstat.h"
29 : #include "postgres_fdw.h"
30 : #include "storage/latch.h"
31 : #include "utils/builtins.h"
32 : #include "utils/hsearch.h"
33 : #include "utils/inval.h"
34 : #include "utils/syscache.h"
35 :
36 : /*
37 : * Connection cache hash table entry
38 : *
39 : * The lookup key in this hash table is the user mapping OID. We use just one
40 : * connection per user mapping ID, which ensures that all the scans use the
41 : * same snapshot during a query. Using the user mapping OID rather than
42 : * the foreign server OID + user OID avoids creating multiple connections when
43 : * the public user mapping applies to all user OIDs.
44 : *
45 : * The "conn" pointer can be NULL if we don't currently have a live connection.
46 : * When we do have a connection, xact_depth tracks the current depth of
47 : * transactions and subtransactions open on the remote side. We need to issue
48 : * commands at the same nesting depth on the remote as we're executing at
49 : * ourselves, so that rolling back a subtransaction will kill the right
50 : * queries and not the wrong ones.
51 : */
52 : typedef Oid ConnCacheKey;
53 :
54 : typedef struct ConnCacheEntry
55 : {
56 : ConnCacheKey key; /* hash key (must be first) */
57 : PGconn *conn; /* connection to foreign server, or NULL */
58 : /* Remaining fields are invalid when conn is NULL: */
59 : int xact_depth; /* 0 = no xact open, 1 = main xact open, 2 =
60 : * one level of subxact open, etc */
61 : bool have_prep_stmt; /* have we prepared any stmts in this xact? */
62 : bool have_error; /* have any subxacts aborted in this xact? */
63 : bool changing_xact_state; /* xact state change in process */
64 : bool parallel_commit; /* do we commit (sub)xacts in parallel? */
65 : bool parallel_abort; /* do we abort (sub)xacts in parallel? */
66 : bool invalidated; /* true if reconnect is pending */
67 : bool keep_connections; /* setting value of keep_connections
68 : * server option */
69 : Oid serverid; /* foreign server OID used to get server name */
70 : uint32 server_hashvalue; /* hash value of foreign server OID */
71 : uint32 mapping_hashvalue; /* hash value of user mapping OID */
72 : PgFdwConnState state; /* extra per-connection state */
73 : } ConnCacheEntry;
74 :
75 : /*
76 : * Connection cache (initialized on first use)
77 : */
78 : static HTAB *ConnectionHash = NULL;
79 :
80 : /* for assigning cursor numbers and prepared statement numbers */
81 : static unsigned int cursor_number = 0;
82 : static unsigned int prep_stmt_number = 0;
83 :
84 : /* tracks whether any work is needed in callback functions */
85 : static bool xact_got_connection = false;
86 :
87 : /* custom wait event values, retrieved from shared memory */
88 : static uint32 pgfdw_we_cleanup_result = 0;
89 : static uint32 pgfdw_we_connect = 0;
90 : static uint32 pgfdw_we_get_result = 0;
91 :
92 : /*
93 : * Milliseconds to wait to cancel an in-progress query or execute a cleanup
94 : * query; if it takes longer than 30 seconds to do these, we assume the
95 : * connection is dead.
96 : */
97 : #define CONNECTION_CLEANUP_TIMEOUT 30000
98 :
99 : /*
100 : * Milliseconds to wait before issuing another cancel request. This covers
101 : * the race condition where the remote session ignored our cancel request
102 : * because it arrived while idle.
103 : */
104 : #define RETRY_CANCEL_TIMEOUT 1000
105 :
106 : /* Macro for constructing abort command to be sent */
107 : #define CONSTRUCT_ABORT_COMMAND(sql, entry, toplevel) \
108 : do { \
109 : if (toplevel) \
110 : snprintf((sql), sizeof(sql), \
111 : "ABORT TRANSACTION"); \
112 : else \
113 : snprintf((sql), sizeof(sql), \
114 : "ROLLBACK TO SAVEPOINT s%d; RELEASE SAVEPOINT s%d", \
115 : (entry)->xact_depth, (entry)->xact_depth); \
116 : } while(0)
117 :
118 : /*
119 : * Extension version number, for supporting older extension versions' objects
120 : */
121 : enum pgfdwVersion
122 : {
123 : PGFDW_V1_1 = 0,
124 : PGFDW_V1_2,
125 : };
126 :
127 : /*
128 : * SQL functions
129 : */
130 4 : PG_FUNCTION_INFO_V1(postgres_fdw_get_connections);
131 6 : PG_FUNCTION_INFO_V1(postgres_fdw_get_connections_1_2);
132 6 : PG_FUNCTION_INFO_V1(postgres_fdw_disconnect);
133 6 : PG_FUNCTION_INFO_V1(postgres_fdw_disconnect_all);
134 :
135 : /* prototypes of private functions */
136 : static void make_new_connection(ConnCacheEntry *entry, UserMapping *user);
137 : static PGconn *connect_pg_server(ForeignServer *server, UserMapping *user);
138 : static void disconnect_pg_server(ConnCacheEntry *entry);
139 : static void check_conn_params(const char **keywords, const char **values, UserMapping *user);
140 : static void configure_remote_session(PGconn *conn);
141 : static void do_sql_command_begin(PGconn *conn, const char *sql);
142 : static void do_sql_command_end(PGconn *conn, const char *sql,
143 : bool consume_input);
144 : static void begin_remote_xact(ConnCacheEntry *entry);
145 : static void pgfdw_report_internal(int elevel, PGresult *res, PGconn *conn,
146 : const char *sql);
147 : static void pgfdw_xact_callback(XactEvent event, void *arg);
148 : static void pgfdw_subxact_callback(SubXactEvent event,
149 : SubTransactionId mySubid,
150 : SubTransactionId parentSubid,
151 : void *arg);
152 : static void pgfdw_inval_callback(Datum arg, int cacheid, uint32 hashvalue);
153 : static void pgfdw_reject_incomplete_xact_state_change(ConnCacheEntry *entry);
154 : static void pgfdw_reset_xact_state(ConnCacheEntry *entry, bool toplevel);
155 : static bool pgfdw_cancel_query(PGconn *conn);
156 : static bool pgfdw_cancel_query_begin(PGconn *conn, TimestampTz endtime);
157 : static bool pgfdw_cancel_query_end(PGconn *conn, TimestampTz endtime,
158 : TimestampTz retrycanceltime,
159 : bool consume_input);
160 : static bool pgfdw_exec_cleanup_query(PGconn *conn, const char *query,
161 : bool ignore_errors);
162 : static bool pgfdw_exec_cleanup_query_begin(PGconn *conn, const char *query);
163 : static bool pgfdw_exec_cleanup_query_end(PGconn *conn, const char *query,
164 : TimestampTz endtime,
165 : bool consume_input,
166 : bool ignore_errors);
167 : static bool pgfdw_get_cleanup_result(PGconn *conn, TimestampTz endtime,
168 : TimestampTz retrycanceltime,
169 : PGresult **result, bool *timed_out);
170 : static void pgfdw_abort_cleanup(ConnCacheEntry *entry, bool toplevel);
171 : static bool pgfdw_abort_cleanup_begin(ConnCacheEntry *entry, bool toplevel,
172 : List **pending_entries,
173 : List **cancel_requested);
174 : static void pgfdw_finish_pre_commit_cleanup(List *pending_entries);
175 : static void pgfdw_finish_pre_subcommit_cleanup(List *pending_entries,
176 : int curlevel);
177 : static void pgfdw_finish_abort_cleanup(List *pending_entries,
178 : List *cancel_requested,
179 : bool toplevel);
180 : static void pgfdw_security_check(const char **keywords, const char **values,
181 : UserMapping *user, PGconn *conn);
182 : static bool UserMappingPasswordRequired(UserMapping *user);
183 : static bool UseScramPassthrough(ForeignServer *server, UserMapping *user);
184 : static bool disconnect_cached_connections(Oid serverid);
185 : static void postgres_fdw_get_connections_internal(FunctionCallInfo fcinfo,
186 : enum pgfdwVersion api_version);
187 : static int pgfdw_conn_check(PGconn *conn);
188 : static bool pgfdw_conn_checkable(void);
189 : static bool pgfdw_has_required_scram_options(const char **keywords, const char **values);
190 :
191 : /*
192 : * Get a PGconn which can be used to execute queries on the remote PostgreSQL
193 : * server with the user's authorization. A new connection is established
194 : * if we don't already have a suitable one, and a transaction is opened at
195 : * the right subtransaction nesting depth if we didn't do that already.
196 : *
197 : * will_prep_stmt must be true if caller intends to create any prepared
198 : * statements. Since those don't go away automatically at transaction end
199 : * (not even on error), we need this flag to cue manual cleanup.
200 : *
201 : * If state is not NULL, *state receives the per-connection state associated
202 : * with the PGconn.
203 : */
204 : PGconn *
205 4346 : GetConnection(UserMapping *user, bool will_prep_stmt, PgFdwConnState **state)
206 : {
207 : bool found;
208 4346 : bool retry = false;
209 : ConnCacheEntry *entry;
210 : ConnCacheKey key;
211 4346 : MemoryContext ccxt = CurrentMemoryContext;
212 :
213 : /* First time through, initialize connection cache hashtable */
214 4346 : if (ConnectionHash == NULL)
215 : {
216 : HASHCTL ctl;
217 :
218 18 : if (pgfdw_we_get_result == 0)
219 18 : pgfdw_we_get_result =
220 18 : WaitEventExtensionNew("PostgresFdwGetResult");
221 :
222 18 : ctl.keysize = sizeof(ConnCacheKey);
223 18 : ctl.entrysize = sizeof(ConnCacheEntry);
224 18 : ConnectionHash = hash_create("postgres_fdw connections", 8,
225 : &ctl,
226 : HASH_ELEM | HASH_BLOBS);
227 :
228 : /*
229 : * Register some callback functions that manage connection cleanup.
230 : * This should be done just once in each backend.
231 : */
232 18 : RegisterXactCallback(pgfdw_xact_callback, NULL);
233 18 : RegisterSubXactCallback(pgfdw_subxact_callback, NULL);
234 18 : CacheRegisterSyscacheCallback(FOREIGNSERVEROID,
235 : pgfdw_inval_callback, (Datum) 0);
236 18 : CacheRegisterSyscacheCallback(USERMAPPINGOID,
237 : pgfdw_inval_callback, (Datum) 0);
238 : }
239 :
240 : /* Set flag that we did GetConnection during the current transaction */
241 4346 : xact_got_connection = true;
242 :
243 : /* Create hash key for the entry. Assume no pad bytes in key struct */
244 4346 : key = user->umid;
245 :
246 : /*
247 : * Find or create cached entry for requested connection.
248 : */
249 4346 : entry = hash_search(ConnectionHash, &key, HASH_ENTER, &found);
250 4346 : if (!found)
251 : {
252 : /*
253 : * We need only clear "conn" here; remaining fields will be filled
254 : * later when "conn" is set.
255 : */
256 34 : entry->conn = NULL;
257 : }
258 :
259 : /* Reject further use of connections which failed abort cleanup. */
260 4346 : pgfdw_reject_incomplete_xact_state_change(entry);
261 :
262 : /*
263 : * If the connection needs to be remade due to invalidation, disconnect as
264 : * soon as we're out of all transactions.
265 : */
266 4346 : if (entry->conn != NULL && entry->invalidated && entry->xact_depth == 0)
267 : {
268 0 : elog(DEBUG3, "closing connection %p for option changes to take effect",
269 : entry->conn);
270 0 : disconnect_pg_server(entry);
271 : }
272 :
273 : /*
274 : * If cache entry doesn't have a connection, we have to establish a new
275 : * connection. (If connect_pg_server throws an error, the cache entry
276 : * will remain in a valid empty state, ie conn == NULL.)
277 : */
278 4346 : if (entry->conn == NULL)
279 140 : make_new_connection(entry, user);
280 :
281 : /*
282 : * We check the health of the cached connection here when using it. In
283 : * cases where we're out of all transactions, if a broken connection is
284 : * detected, we try to reestablish a new connection later.
285 : */
286 4334 : PG_TRY();
287 : {
288 : /* Process a pending asynchronous request if any. */
289 4334 : if (entry->state.pendingAreq)
290 0 : process_pending_request(entry->state.pendingAreq);
291 : /* Start a new transaction or subtransaction if needed. */
292 4334 : begin_remote_xact(entry);
293 : }
294 4 : PG_CATCH();
295 : {
296 4 : MemoryContext ecxt = MemoryContextSwitchTo(ccxt);
297 4 : ErrorData *errdata = CopyErrorData();
298 :
299 : /*
300 : * Determine whether to try to reestablish the connection.
301 : *
302 : * After a broken connection is detected in libpq, any error other
303 : * than connection failure (e.g., out-of-memory) can be thrown
304 : * somewhere between return from libpq and the expected ereport() call
305 : * in pgfdw_report_error(). In this case, since PQstatus() indicates
306 : * CONNECTION_BAD, checking only PQstatus() causes the false detection
307 : * of connection failure. To avoid this, we also verify that the
308 : * error's sqlstate is ERRCODE_CONNECTION_FAILURE. Note that also
309 : * checking only the sqlstate can cause another false detection
310 : * because pgfdw_report_error() may report ERRCODE_CONNECTION_FAILURE
311 : * for any libpq-originated error condition.
312 : */
313 4 : if (errdata->sqlerrcode != ERRCODE_CONNECTION_FAILURE ||
314 4 : PQstatus(entry->conn) != CONNECTION_BAD ||
315 4 : entry->xact_depth > 0)
316 : {
317 2 : MemoryContextSwitchTo(ecxt);
318 2 : PG_RE_THROW();
319 : }
320 :
321 : /* Clean up the error state */
322 2 : FlushErrorState();
323 2 : FreeErrorData(errdata);
324 2 : errdata = NULL;
325 :
326 2 : retry = true;
327 : }
328 4332 : PG_END_TRY();
329 :
330 : /*
331 : * If a broken connection is detected, disconnect it, reestablish a new
332 : * connection and retry a new remote transaction. If connection failure is
333 : * reported again, we give up getting a connection.
334 : */
335 4332 : if (retry)
336 : {
337 : Assert(entry->xact_depth == 0);
338 :
339 2 : ereport(DEBUG3,
340 : (errmsg_internal("could not start remote transaction on connection %p",
341 : entry->conn)),
342 : errdetail_internal("%s", pchomp(PQerrorMessage(entry->conn))));
343 :
344 2 : elog(DEBUG3, "closing connection %p to reestablish a new one",
345 : entry->conn);
346 2 : disconnect_pg_server(entry);
347 :
348 2 : make_new_connection(entry, user);
349 :
350 2 : begin_remote_xact(entry);
351 : }
352 :
353 : /* Remember if caller will prepare statements */
354 4332 : entry->have_prep_stmt |= will_prep_stmt;
355 :
356 : /* If caller needs access to the per-connection state, return it. */
357 4332 : if (state)
358 1466 : *state = &entry->state;
359 :
360 4332 : return entry->conn;
361 : }
362 :
363 : /*
364 : * Reset all transient state fields in the cached connection entry and
365 : * establish new connection to the remote server.
366 : */
367 : static void
368 142 : make_new_connection(ConnCacheEntry *entry, UserMapping *user)
369 : {
370 142 : ForeignServer *server = GetForeignServer(user->serverid);
371 : ListCell *lc;
372 :
373 : Assert(entry->conn == NULL);
374 :
375 : /* Reset all transient state fields, to be sure all are clean */
376 142 : entry->xact_depth = 0;
377 142 : entry->have_prep_stmt = false;
378 142 : entry->have_error = false;
379 142 : entry->changing_xact_state = false;
380 142 : entry->invalidated = false;
381 142 : entry->serverid = server->serverid;
382 142 : entry->server_hashvalue =
383 142 : GetSysCacheHashValue1(FOREIGNSERVEROID,
384 : ObjectIdGetDatum(server->serverid));
385 142 : entry->mapping_hashvalue =
386 142 : GetSysCacheHashValue1(USERMAPPINGOID,
387 : ObjectIdGetDatum(user->umid));
388 142 : memset(&entry->state, 0, sizeof(entry->state));
389 :
390 : /*
391 : * Determine whether to keep the connection that we're about to make here
392 : * open even after the transaction using it ends, so that the subsequent
393 : * transactions can re-use it.
394 : *
395 : * By default, all the connections to any foreign servers are kept open.
396 : *
397 : * Also determine whether to commit/abort (sub)transactions opened on the
398 : * remote server in parallel at (sub)transaction end, which is disabled by
399 : * default.
400 : *
401 : * Note: it's enough to determine these only when making a new connection
402 : * because if these settings for it are changed, it will be closed and
403 : * re-made later.
404 : */
405 142 : entry->keep_connections = true;
406 142 : entry->parallel_commit = false;
407 142 : entry->parallel_abort = false;
408 630 : foreach(lc, server->options)
409 : {
410 488 : DefElem *def = (DefElem *) lfirst(lc);
411 :
412 488 : if (strcmp(def->defname, "keep_connections") == 0)
413 16 : entry->keep_connections = defGetBoolean(def);
414 472 : else if (strcmp(def->defname, "parallel_commit") == 0)
415 4 : entry->parallel_commit = defGetBoolean(def);
416 468 : else if (strcmp(def->defname, "parallel_abort") == 0)
417 4 : entry->parallel_abort = defGetBoolean(def);
418 : }
419 :
420 : /* Now try to make the connection */
421 142 : entry->conn = connect_pg_server(server, user);
422 :
423 130 : elog(DEBUG3, "new postgres_fdw connection %p for server \"%s\" (user mapping oid %u, userid %u)",
424 : entry->conn, server->servername, user->umid, user->userid);
425 130 : }
426 :
427 : /*
428 : * Check that non-superuser has used password or delegated credentials
429 : * to establish connection; otherwise, he's piggybacking on the
430 : * postgres server's user identity. See also dblink_security_check()
431 : * in contrib/dblink and check_conn_params.
432 : */
433 : static void
434 134 : pgfdw_security_check(const char **keywords, const char **values, UserMapping *user, PGconn *conn)
435 : {
436 : /* Superusers bypass the check */
437 134 : if (superuser_arg(user->userid))
438 118 : return;
439 :
440 : #ifdef ENABLE_GSS
441 : /* Connected via GSSAPI with delegated credentials- all good. */
442 : if (PQconnectionUsedGSSAPI(conn) && be_gssapi_get_delegation(MyProcPort))
443 : return;
444 : #endif
445 :
446 : /* Ok if superuser set PW required false. */
447 16 : if (!UserMappingPasswordRequired(user))
448 4 : return;
449 :
450 : /* Connected via PW, with PW required true, and provided non-empty PW. */
451 12 : if (PQconnectionUsedPassword(conn))
452 : {
453 : /* ok if params contain a non-empty password */
454 80 : for (int i = 0; keywords[i] != NULL; i++)
455 : {
456 72 : if (strcmp(keywords[i], "password") == 0 && values[i][0] != '\0')
457 0 : return;
458 : }
459 : }
460 :
461 : /*
462 : * Ok if SCRAM pass-through is being used and all required SCRAM options
463 : * are set correctly. If pgfdw_has_required_scram_options returns true we
464 : * assume that UseScramPassthrough is also true since SCRAM options are
465 : * only set when UseScramPassthrough is enabled.
466 : */
467 12 : if (MyProcPort->has_scram_keys && pgfdw_has_required_scram_options(keywords, values))
468 8 : return;
469 :
470 4 : ereport(ERROR,
471 : (errcode(ERRCODE_S_R_E_PROHIBITED_SQL_STATEMENT_ATTEMPTED),
472 : errmsg("password or GSSAPI delegated credentials required"),
473 : errdetail("Non-superuser cannot connect if the server does not request a password or use GSSAPI with delegated credentials."),
474 : errhint("Target server's authentication method must be changed or password_required=false set in the user mapping attributes.")));
475 : }
476 :
477 : /*
478 : * Connect to remote server using specified server and user mapping properties.
479 : */
480 : static PGconn *
481 142 : connect_pg_server(ForeignServer *server, UserMapping *user)
482 : {
483 142 : PGconn *volatile conn = NULL;
484 :
485 : /*
486 : * Use PG_TRY block to ensure closing connection on error.
487 : */
488 142 : PG_TRY();
489 : {
490 : const char **keywords;
491 : const char **values;
492 142 : char *appname = NULL;
493 : int n;
494 :
495 : /*
496 : * Construct connection params from generic options of ForeignServer
497 : * and UserMapping. (Some of them might not be libpq options, in
498 : * which case we'll just waste a few array slots.) Add 4 extra slots
499 : * for application_name, fallback_application_name, client_encoding,
500 : * end marker, and 3 extra slots for scram keys and required scram
501 : * pass-through options.
502 : */
503 142 : n = list_length(server->options) + list_length(user->options) + 4 + 3;
504 142 : keywords = (const char **) palloc(n * sizeof(char *));
505 142 : values = (const char **) palloc(n * sizeof(char *));
506 :
507 142 : n = 0;
508 284 : n += ExtractConnectionOptions(server->options,
509 142 : keywords + n, values + n);
510 284 : n += ExtractConnectionOptions(user->options,
511 142 : keywords + n, values + n);
512 :
513 : /*
514 : * Use pgfdw_application_name as application_name if set.
515 : *
516 : * PQconnectdbParams() processes the parameter arrays from start to
517 : * end. If any key word is repeated, the last value is used. Therefore
518 : * note that pgfdw_application_name must be added to the arrays after
519 : * options of ForeignServer are, so that it can override
520 : * application_name set in ForeignServer.
521 : */
522 142 : if (pgfdw_application_name && *pgfdw_application_name != '\0')
523 : {
524 2 : keywords[n] = "application_name";
525 2 : values[n] = pgfdw_application_name;
526 2 : n++;
527 : }
528 :
529 : /*
530 : * Search the parameter arrays to find application_name setting, and
531 : * replace escape sequences in it with status information if found.
532 : * The arrays are searched backwards because the last value is used if
533 : * application_name is repeatedly set.
534 : */
535 378 : for (int i = n - 1; i >= 0; i--)
536 : {
537 272 : if (strcmp(keywords[i], "application_name") == 0 &&
538 36 : *(values[i]) != '\0')
539 : {
540 : /*
541 : * Use this application_name setting if it's not empty string
542 : * even after any escape sequences in it are replaced.
543 : */
544 36 : appname = process_pgfdw_appname(values[i]);
545 36 : if (appname[0] != '\0')
546 : {
547 36 : values[i] = appname;
548 36 : break;
549 : }
550 :
551 : /*
552 : * This empty application_name is not used, so we set
553 : * values[i] to NULL and keep searching the array to find the
554 : * next one.
555 : */
556 0 : values[i] = NULL;
557 0 : pfree(appname);
558 0 : appname = NULL;
559 : }
560 : }
561 :
562 : /* Use "postgres_fdw" as fallback_application_name */
563 142 : keywords[n] = "fallback_application_name";
564 142 : values[n] = "postgres_fdw";
565 142 : n++;
566 :
567 : /* Set client_encoding so that libpq can convert encoding properly. */
568 142 : keywords[n] = "client_encoding";
569 142 : values[n] = GetDatabaseEncodingName();
570 142 : n++;
571 :
572 : /* Add required SCRAM pass-through connection options if it's enabled. */
573 142 : if (MyProcPort->has_scram_keys && UseScramPassthrough(server, user))
574 : {
575 : int len;
576 : int encoded_len;
577 :
578 8 : keywords[n] = "scram_client_key";
579 8 : len = pg_b64_enc_len(sizeof(MyProcPort->scram_ClientKey));
580 : /* don't forget the zero-terminator */
581 8 : values[n] = palloc0(len + 1);
582 16 : encoded_len = pg_b64_encode(MyProcPort->scram_ClientKey,
583 : sizeof(MyProcPort->scram_ClientKey),
584 8 : (char *) values[n], len);
585 8 : if (encoded_len < 0)
586 0 : elog(ERROR, "could not encode SCRAM client key");
587 8 : n++;
588 :
589 8 : keywords[n] = "scram_server_key";
590 8 : len = pg_b64_enc_len(sizeof(MyProcPort->scram_ServerKey));
591 : /* don't forget the zero-terminator */
592 8 : values[n] = palloc0(len + 1);
593 16 : encoded_len = pg_b64_encode(MyProcPort->scram_ServerKey,
594 : sizeof(MyProcPort->scram_ServerKey),
595 8 : (char *) values[n], len);
596 8 : if (encoded_len < 0)
597 0 : elog(ERROR, "could not encode SCRAM server key");
598 8 : n++;
599 :
600 : /*
601 : * Require scram-sha-256 to ensure that no other auth method is
602 : * used when connecting with foreign server.
603 : */
604 8 : keywords[n] = "require_auth";
605 8 : values[n] = "scram-sha-256";
606 8 : n++;
607 : }
608 :
609 142 : keywords[n] = values[n] = NULL;
610 :
611 : /* Verify the set of connection parameters. */
612 142 : check_conn_params(keywords, values, user);
613 :
614 : /* first time, allocate or get the custom wait event */
615 138 : if (pgfdw_we_connect == 0)
616 18 : pgfdw_we_connect = WaitEventExtensionNew("PostgresFdwConnect");
617 :
618 : /* OK to make connection */
619 138 : conn = libpqsrv_connect_params(keywords, values,
620 : false, /* expand_dbname */
621 : pgfdw_we_connect);
622 :
623 138 : if (!conn || PQstatus(conn) != CONNECTION_OK)
624 4 : ereport(ERROR,
625 : (errcode(ERRCODE_SQLCLIENT_UNABLE_TO_ESTABLISH_SQLCONNECTION),
626 : errmsg("could not connect to server \"%s\"",
627 : server->servername),
628 : errdetail_internal("%s", pchomp(PQerrorMessage(conn)))));
629 :
630 134 : PQsetNoticeReceiver(conn, libpqsrv_notice_receiver,
631 : "received message via remote connection");
632 :
633 : /* Perform post-connection security checks. */
634 134 : pgfdw_security_check(keywords, values, user, conn);
635 :
636 : /* Prepare new session for use */
637 130 : configure_remote_session(conn);
638 :
639 130 : if (appname != NULL)
640 36 : pfree(appname);
641 130 : pfree(keywords);
642 130 : pfree(values);
643 : }
644 12 : PG_CATCH();
645 : {
646 12 : libpqsrv_disconnect(conn);
647 12 : PG_RE_THROW();
648 : }
649 130 : PG_END_TRY();
650 :
651 130 : return conn;
652 : }
653 :
654 : /*
655 : * Disconnect any open connection for a connection cache entry.
656 : */
657 : static void
658 112 : disconnect_pg_server(ConnCacheEntry *entry)
659 : {
660 112 : if (entry->conn != NULL)
661 : {
662 112 : libpqsrv_disconnect(entry->conn);
663 112 : entry->conn = NULL;
664 : }
665 112 : }
666 :
667 : /*
668 : * Return true if the password_required is defined and false for this user
669 : * mapping, otherwise false. The mapping has been pre-validated.
670 : */
671 : static bool
672 30 : UserMappingPasswordRequired(UserMapping *user)
673 : {
674 : ListCell *cell;
675 :
676 52 : foreach(cell, user->options)
677 : {
678 28 : DefElem *def = (DefElem *) lfirst(cell);
679 :
680 28 : if (strcmp(def->defname, "password_required") == 0)
681 6 : return defGetBoolean(def);
682 : }
683 :
684 24 : return true;
685 : }
686 :
687 : static bool
688 8 : UseScramPassthrough(ForeignServer *server, UserMapping *user)
689 : {
690 : ListCell *cell;
691 :
692 32 : foreach(cell, server->options)
693 : {
694 32 : DefElem *def = (DefElem *) lfirst(cell);
695 :
696 32 : if (strcmp(def->defname, "use_scram_passthrough") == 0)
697 8 : return defGetBoolean(def);
698 : }
699 :
700 0 : foreach(cell, user->options)
701 : {
702 0 : DefElem *def = (DefElem *) lfirst(cell);
703 :
704 0 : if (strcmp(def->defname, "use_scram_passthrough") == 0)
705 0 : return defGetBoolean(def);
706 : }
707 :
708 0 : return false;
709 : }
710 :
711 : /*
712 : * For non-superusers, insist that the connstr specify a password or that the
713 : * user provided their own GSSAPI delegated credentials. This
714 : * prevents a password from being picked up from .pgpass, a service file, the
715 : * environment, etc. We don't want the postgres user's passwords,
716 : * certificates, etc to be accessible to non-superusers. (See also
717 : * dblink_connstr_check in contrib/dblink.)
718 : */
719 : static void
720 142 : check_conn_params(const char **keywords, const char **values, UserMapping *user)
721 : {
722 : int i;
723 :
724 : /* no check required if superuser */
725 142 : if (superuser_arg(user->userid))
726 122 : return;
727 :
728 : #ifdef ENABLE_GSS
729 : /* ok if the user provided their own delegated credentials */
730 : if (be_gssapi_get_delegation(MyProcPort))
731 : return;
732 : #endif
733 :
734 : /* ok if params contain a non-empty password */
735 128 : for (i = 0; keywords[i] != NULL; i++)
736 : {
737 114 : if (strcmp(keywords[i], "password") == 0 && values[i][0] != '\0')
738 6 : return;
739 : }
740 :
741 : /* ok if the superuser explicitly said so at user mapping creation time */
742 14 : if (!UserMappingPasswordRequired(user))
743 2 : return;
744 :
745 : /*
746 : * Ok if SCRAM pass-through is being used and all required scram options
747 : * are set correctly. If pgfdw_has_required_scram_options returns true we
748 : * assume that UseScramPassthrough is also true since SCRAM options are
749 : * only set when UseScramPassthrough is enabled.
750 : */
751 12 : if (MyProcPort->has_scram_keys && pgfdw_has_required_scram_options(keywords, values))
752 8 : return;
753 :
754 4 : ereport(ERROR,
755 : (errcode(ERRCODE_S_R_E_PROHIBITED_SQL_STATEMENT_ATTEMPTED),
756 : errmsg("password or GSSAPI delegated credentials required"),
757 : errdetail("Non-superusers must delegate GSSAPI credentials, provide a password, or enable SCRAM pass-through in user mapping.")));
758 : }
759 :
760 : /*
761 : * Issue SET commands to make sure remote session is configured properly.
762 : *
763 : * We do this just once at connection, assuming nothing will change the
764 : * values later. Since we'll never send volatile function calls to the
765 : * remote, there shouldn't be any way to break this assumption from our end.
766 : * It's possible to think of ways to break it at the remote end, eg making
767 : * a foreign table point to a view that includes a set_config call ---
768 : * but once you admit the possibility of a malicious view definition,
769 : * there are any number of ways to break things.
770 : */
771 : static void
772 130 : configure_remote_session(PGconn *conn)
773 : {
774 130 : int remoteversion = PQserverVersion(conn);
775 :
776 : /* Force the search path to contain only pg_catalog (see deparse.c) */
777 130 : do_sql_command(conn, "SET search_path = pg_catalog");
778 :
779 : /*
780 : * Set remote timezone; this is basically just cosmetic, since all
781 : * transmitted and returned timestamptzs should specify a zone explicitly
782 : * anyway. However it makes the regression test outputs more predictable.
783 : *
784 : * We don't risk setting remote zone equal to ours, since the remote
785 : * server might use a different timezone database. Instead, use GMT
786 : * (quoted, because very old servers are picky about case). That's
787 : * guaranteed to work regardless of the remote's timezone database,
788 : * because pg_tzset() hard-wires it (at least in PG 9.2 and later).
789 : */
790 130 : do_sql_command(conn, "SET timezone = 'GMT'");
791 :
792 : /*
793 : * Set values needed to ensure unambiguous data output from remote. (This
794 : * logic should match what pg_dump does. See also set_transmission_modes
795 : * in postgres_fdw.c.)
796 : */
797 130 : do_sql_command(conn, "SET datestyle = ISO");
798 130 : if (remoteversion >= 80400)
799 130 : do_sql_command(conn, "SET intervalstyle = postgres");
800 130 : if (remoteversion >= 90000)
801 130 : do_sql_command(conn, "SET extra_float_digits = 3");
802 : else
803 0 : do_sql_command(conn, "SET extra_float_digits = 2");
804 130 : }
805 :
806 : /*
807 : * Convenience subroutine to issue a non-data-returning SQL command to remote
808 : */
809 : void
810 3540 : do_sql_command(PGconn *conn, const char *sql)
811 : {
812 3540 : do_sql_command_begin(conn, sql);
813 3540 : do_sql_command_end(conn, sql, false);
814 3534 : }
815 :
816 : static void
817 3576 : do_sql_command_begin(PGconn *conn, const char *sql)
818 : {
819 3576 : if (!PQsendQuery(conn, sql))
820 0 : pgfdw_report_error(NULL, conn, sql);
821 3576 : }
822 :
823 : static void
824 3576 : do_sql_command_end(PGconn *conn, const char *sql, bool consume_input)
825 : {
826 : PGresult *res;
827 :
828 : /*
829 : * If requested, consume whatever data is available from the socket. (Note
830 : * that if all data is available, this allows pgfdw_get_result to call
831 : * PQgetResult without forcing the overhead of WaitLatchOrSocket, which
832 : * would be large compared to the overhead of PQconsumeInput.)
833 : */
834 3576 : if (consume_input && !PQconsumeInput(conn))
835 0 : pgfdw_report_error(NULL, conn, sql);
836 3576 : res = pgfdw_get_result(conn);
837 3576 : if (PQresultStatus(res) != PGRES_COMMAND_OK)
838 6 : pgfdw_report_error(res, conn, sql);
839 3570 : PQclear(res);
840 3570 : }
841 :
842 : /*
843 : * Start remote transaction or subtransaction, if needed.
844 : *
845 : * Note that we always use at least REPEATABLE READ in the remote session.
846 : * This is so that, if a query initiates multiple scans of the same or
847 : * different foreign tables, we will get snapshot-consistent results from
848 : * those scans. A disadvantage is that we can't provide sane emulation of
849 : * READ COMMITTED behavior --- it would be nice if we had some other way to
850 : * control which remote queries share a snapshot.
851 : */
852 : static void
853 4336 : begin_remote_xact(ConnCacheEntry *entry)
854 : {
855 4336 : int curlevel = GetCurrentTransactionNestLevel();
856 :
857 : /* Start main transaction if we haven't yet */
858 4336 : if (entry->xact_depth <= 0)
859 : {
860 : const char *sql;
861 :
862 1474 : elog(DEBUG3, "starting remote transaction on connection %p",
863 : entry->conn);
864 :
865 1474 : if (IsolationIsSerializable())
866 0 : sql = "START TRANSACTION ISOLATION LEVEL SERIALIZABLE";
867 : else
868 1474 : sql = "START TRANSACTION ISOLATION LEVEL REPEATABLE READ";
869 1474 : entry->changing_xact_state = true;
870 1474 : do_sql_command(entry->conn, sql);
871 1472 : entry->xact_depth = 1;
872 1472 : entry->changing_xact_state = false;
873 : }
874 :
875 : /*
876 : * If we're in a subtransaction, stack up savepoints to match our level.
877 : * This ensures we can rollback just the desired effects when a
878 : * subtransaction aborts.
879 : */
880 4362 : while (entry->xact_depth < curlevel)
881 : {
882 : char sql[64];
883 :
884 30 : snprintf(sql, sizeof(sql), "SAVEPOINT s%d", entry->xact_depth + 1);
885 30 : entry->changing_xact_state = true;
886 30 : do_sql_command(entry->conn, sql);
887 28 : entry->xact_depth++;
888 28 : entry->changing_xact_state = false;
889 : }
890 4332 : }
891 :
892 : /*
893 : * Release connection reference count created by calling GetConnection.
894 : */
895 : void
896 4226 : ReleaseConnection(PGconn *conn)
897 : {
898 : /*
899 : * Currently, we don't actually track connection references because all
900 : * cleanup is managed on a transaction or subtransaction basis instead. So
901 : * there's nothing to do here.
902 : */
903 4226 : }
904 :
905 : /*
906 : * Assign a "unique" number for a cursor.
907 : *
908 : * These really only need to be unique per connection within a transaction.
909 : * For the moment we ignore the per-connection point and assign them across
910 : * all connections in the transaction, but we ask for the connection to be
911 : * supplied in case we want to refine that.
912 : *
913 : * Note that even if wraparound happens in a very long transaction, actual
914 : * collisions are highly improbable; just be sure to use %u not %d to print.
915 : */
916 : unsigned int
917 1060 : GetCursorNumber(PGconn *conn)
918 : {
919 1060 : return ++cursor_number;
920 : }
921 :
922 : /*
923 : * Assign a "unique" number for a prepared statement.
924 : *
925 : * This works much like GetCursorNumber, except that we never reset the counter
926 : * within a session. That's because we can't be 100% sure we've gotten rid
927 : * of all prepared statements on all connections, and it's not really worth
928 : * increasing the risk of prepared-statement name collisions by resetting.
929 : */
930 : unsigned int
931 356 : GetPrepStmtNumber(PGconn *conn)
932 : {
933 356 : return ++prep_stmt_number;
934 : }
935 :
936 : /*
937 : * Submit a query and wait for the result.
938 : *
939 : * Since we don't use non-blocking mode, this can't process interrupts while
940 : * pushing the query text to the server. That risk is relatively small, so we
941 : * ignore that for now.
942 : *
943 : * Caller is responsible for the error handling on the result.
944 : */
945 : PGresult *
946 7980 : pgfdw_exec_query(PGconn *conn, const char *query, PgFdwConnState *state)
947 : {
948 : /* First, process a pending asynchronous request, if any. */
949 7980 : if (state && state->pendingAreq)
950 8 : process_pending_request(state->pendingAreq);
951 :
952 7980 : if (!PQsendQuery(conn, query))
953 0 : return NULL;
954 7980 : return pgfdw_get_result(conn);
955 : }
956 :
957 : /*
958 : * Wrap libpqsrv_get_result_last(), adding wait event.
959 : *
960 : * Caller is responsible for the error handling on the result.
961 : */
962 : PGresult *
963 16102 : pgfdw_get_result(PGconn *conn)
964 : {
965 16102 : return libpqsrv_get_result_last(conn, pgfdw_we_get_result);
966 : }
967 :
968 : /*
969 : * Report an error we got from the remote server.
970 : *
971 : * Callers should use pgfdw_report_error() to throw an error, or use
972 : * pgfdw_report() for lesser message levels. (We make this distinction
973 : * so that pgfdw_report_error() can be marked noreturn.)
974 : *
975 : * res: PGresult containing the error (might be NULL)
976 : * conn: connection we did the query on
977 : * sql: NULL, or text of remote command we tried to execute
978 : *
979 : * If "res" is not NULL, it'll be PQclear'ed here (unless we throw error,
980 : * in which case memory context cleanup will clear it eventually).
981 : *
982 : * Note: callers that choose not to throw ERROR for a remote error are
983 : * responsible for making sure that the associated ConnCacheEntry gets
984 : * marked with have_error = true.
985 : */
986 : void
987 32 : pgfdw_report_error(PGresult *res, PGconn *conn, const char *sql)
988 : {
989 32 : pgfdw_report_internal(ERROR, res, conn, sql);
990 0 : pg_unreachable();
991 : }
992 :
993 : void
994 0 : pgfdw_report(int elevel, PGresult *res, PGconn *conn, const char *sql)
995 : {
996 : Assert(elevel < ERROR); /* use pgfdw_report_error for that */
997 0 : pgfdw_report_internal(elevel, res, conn, sql);
998 0 : }
999 :
1000 : static void
1001 32 : pgfdw_report_internal(int elevel, PGresult *res, PGconn *conn,
1002 : const char *sql)
1003 : {
1004 32 : char *diag_sqlstate = PQresultErrorField(res, PG_DIAG_SQLSTATE);
1005 32 : char *message_primary = PQresultErrorField(res, PG_DIAG_MESSAGE_PRIMARY);
1006 32 : char *message_detail = PQresultErrorField(res, PG_DIAG_MESSAGE_DETAIL);
1007 32 : char *message_hint = PQresultErrorField(res, PG_DIAG_MESSAGE_HINT);
1008 32 : char *message_context = PQresultErrorField(res, PG_DIAG_CONTEXT);
1009 : int sqlstate;
1010 :
1011 32 : if (diag_sqlstate)
1012 28 : sqlstate = MAKE_SQLSTATE(diag_sqlstate[0],
1013 : diag_sqlstate[1],
1014 : diag_sqlstate[2],
1015 : diag_sqlstate[3],
1016 : diag_sqlstate[4]);
1017 : else
1018 4 : sqlstate = ERRCODE_CONNECTION_FAILURE;
1019 :
1020 : /*
1021 : * If we don't get a message from the PGresult, try the PGconn. This is
1022 : * needed because for connection-level failures, PQgetResult may just
1023 : * return NULL, not a PGresult at all.
1024 : */
1025 32 : if (message_primary == NULL)
1026 4 : message_primary = pchomp(PQerrorMessage(conn));
1027 :
1028 32 : ereport(elevel,
1029 : (errcode(sqlstate),
1030 : (message_primary != NULL && message_primary[0] != '\0') ?
1031 : errmsg_internal("%s", message_primary) :
1032 : errmsg("could not obtain message string for remote error"),
1033 : message_detail ? errdetail_internal("%s", message_detail) : 0,
1034 : message_hint ? errhint("%s", message_hint) : 0,
1035 : message_context ? errcontext("%s", message_context) : 0,
1036 : sql ? errcontext("remote SQL command: %s", sql) : 0));
1037 0 : PQclear(res);
1038 0 : }
1039 :
1040 : /*
1041 : * pgfdw_xact_callback --- cleanup at main-transaction end.
1042 : *
1043 : * This runs just late enough that it must not enter user-defined code
1044 : * locally. (Entering such code on the remote side is fine. Its remote
1045 : * COMMIT TRANSACTION may run deferred triggers.)
1046 : */
1047 : static void
1048 7942 : pgfdw_xact_callback(XactEvent event, void *arg)
1049 : {
1050 : HASH_SEQ_STATUS scan;
1051 : ConnCacheEntry *entry;
1052 7942 : List *pending_entries = NIL;
1053 7942 : List *cancel_requested = NIL;
1054 :
1055 : /* Quick exit if no connections were touched in this transaction. */
1056 7942 : if (!xact_got_connection)
1057 6532 : return;
1058 :
1059 : /*
1060 : * Scan all connection cache entries to find open remote transactions, and
1061 : * close them.
1062 : */
1063 1410 : hash_seq_init(&scan, ConnectionHash);
1064 7226 : while ((entry = (ConnCacheEntry *) hash_seq_search(&scan)))
1065 : {
1066 : PGresult *res;
1067 :
1068 : /* Ignore cache entry if no open connection right now */
1069 5818 : if (entry->conn == NULL)
1070 3288 : continue;
1071 :
1072 : /* If it has an open remote transaction, try to close it */
1073 2530 : if (entry->xact_depth > 0)
1074 : {
1075 1474 : elog(DEBUG3, "closing remote transaction on connection %p",
1076 : entry->conn);
1077 :
1078 1474 : switch (event)
1079 : {
1080 1384 : case XACT_EVENT_PARALLEL_PRE_COMMIT:
1081 : case XACT_EVENT_PRE_COMMIT:
1082 :
1083 : /*
1084 : * If abort cleanup previously failed for this connection,
1085 : * we can't issue any more commands against it.
1086 : */
1087 1384 : pgfdw_reject_incomplete_xact_state_change(entry);
1088 :
1089 : /* Commit all remote transactions during pre-commit */
1090 1384 : entry->changing_xact_state = true;
1091 1384 : if (entry->parallel_commit)
1092 : {
1093 32 : do_sql_command_begin(entry->conn, "COMMIT TRANSACTION");
1094 32 : pending_entries = lappend(pending_entries, entry);
1095 32 : continue;
1096 : }
1097 1352 : do_sql_command(entry->conn, "COMMIT TRANSACTION");
1098 1352 : entry->changing_xact_state = false;
1099 :
1100 : /*
1101 : * If there were any errors in subtransactions, and we
1102 : * made prepared statements, do a DEALLOCATE ALL to make
1103 : * sure we get rid of all prepared statements. This is
1104 : * annoying and not terribly bulletproof, but it's
1105 : * probably not worth trying harder.
1106 : *
1107 : * DEALLOCATE ALL only exists in 8.3 and later, so this
1108 : * constrains how old a server postgres_fdw can
1109 : * communicate with. We intentionally ignore errors in
1110 : * the DEALLOCATE, so that we can hobble along to some
1111 : * extent with older servers (leaking prepared statements
1112 : * as we go; but we don't really support update operations
1113 : * pre-8.3 anyway).
1114 : */
1115 1352 : if (entry->have_prep_stmt && entry->have_error)
1116 : {
1117 0 : res = pgfdw_exec_query(entry->conn, "DEALLOCATE ALL",
1118 : NULL);
1119 0 : PQclear(res);
1120 : }
1121 1352 : entry->have_prep_stmt = false;
1122 1352 : entry->have_error = false;
1123 1352 : break;
1124 2 : case XACT_EVENT_PRE_PREPARE:
1125 :
1126 : /*
1127 : * We disallow any remote transactions, since it's not
1128 : * very reasonable to hold them open until the prepared
1129 : * transaction is committed. For the moment, throw error
1130 : * unconditionally; later we might allow read-only cases.
1131 : * Note that the error will cause us to come right back
1132 : * here with event == XACT_EVENT_ABORT, so we'll clean up
1133 : * the connection state at that point.
1134 : */
1135 2 : ereport(ERROR,
1136 : (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
1137 : errmsg("cannot PREPARE a transaction that has operated on postgres_fdw foreign tables")));
1138 : break;
1139 0 : case XACT_EVENT_PARALLEL_COMMIT:
1140 : case XACT_EVENT_COMMIT:
1141 : case XACT_EVENT_PREPARE:
1142 : /* Pre-commit should have closed the open transaction */
1143 0 : elog(ERROR, "missed cleaning up connection during pre-commit");
1144 : break;
1145 88 : case XACT_EVENT_PARALLEL_ABORT:
1146 : case XACT_EVENT_ABORT:
1147 : /* Rollback all remote transactions during abort */
1148 88 : if (entry->parallel_abort)
1149 : {
1150 8 : if (pgfdw_abort_cleanup_begin(entry, true,
1151 : &pending_entries,
1152 : &cancel_requested))
1153 8 : continue;
1154 : }
1155 : else
1156 80 : pgfdw_abort_cleanup(entry, true);
1157 80 : break;
1158 : }
1159 : }
1160 :
1161 : /* Reset state to show we're out of a transaction */
1162 2488 : pgfdw_reset_xact_state(entry, true);
1163 : }
1164 :
1165 : /* If there are any pending connections, finish cleaning them up */
1166 1408 : if (pending_entries || cancel_requested)
1167 : {
1168 30 : if (event == XACT_EVENT_PARALLEL_PRE_COMMIT ||
1169 : event == XACT_EVENT_PRE_COMMIT)
1170 : {
1171 : Assert(cancel_requested == NIL);
1172 26 : pgfdw_finish_pre_commit_cleanup(pending_entries);
1173 : }
1174 : else
1175 : {
1176 : Assert(event == XACT_EVENT_PARALLEL_ABORT ||
1177 : event == XACT_EVENT_ABORT);
1178 4 : pgfdw_finish_abort_cleanup(pending_entries, cancel_requested,
1179 : true);
1180 : }
1181 : }
1182 :
1183 : /*
1184 : * Regardless of the event type, we can now mark ourselves as out of the
1185 : * transaction. (Note: if we are here during PRE_COMMIT or PRE_PREPARE,
1186 : * this saves a useless scan of the hashtable during COMMIT or PREPARE.)
1187 : */
1188 1408 : xact_got_connection = false;
1189 :
1190 : /* Also reset cursor numbering for next transaction */
1191 1408 : cursor_number = 0;
1192 : }
1193 :
1194 : /*
1195 : * pgfdw_subxact_callback --- cleanup at subtransaction end.
1196 : */
1197 : static void
1198 76 : pgfdw_subxact_callback(SubXactEvent event, SubTransactionId mySubid,
1199 : SubTransactionId parentSubid, void *arg)
1200 : {
1201 : HASH_SEQ_STATUS scan;
1202 : ConnCacheEntry *entry;
1203 : int curlevel;
1204 76 : List *pending_entries = NIL;
1205 76 : List *cancel_requested = NIL;
1206 :
1207 : /* Nothing to do at subxact start, nor after commit. */
1208 76 : if (!(event == SUBXACT_EVENT_PRE_COMMIT_SUB ||
1209 : event == SUBXACT_EVENT_ABORT_SUB))
1210 46 : return;
1211 :
1212 : /* Quick exit if no connections were touched in this transaction. */
1213 30 : if (!xact_got_connection)
1214 0 : return;
1215 :
1216 : /*
1217 : * Scan all connection cache entries to find open remote subtransactions
1218 : * of the current level, and close them.
1219 : */
1220 30 : curlevel = GetCurrentTransactionNestLevel();
1221 30 : hash_seq_init(&scan, ConnectionHash);
1222 204 : while ((entry = (ConnCacheEntry *) hash_seq_search(&scan)))
1223 : {
1224 : char sql[100];
1225 :
1226 : /*
1227 : * We only care about connections with open remote subtransactions of
1228 : * the current level.
1229 : */
1230 174 : if (entry->conn == NULL || entry->xact_depth < curlevel)
1231 158 : continue;
1232 :
1233 28 : if (entry->xact_depth > curlevel)
1234 0 : elog(ERROR, "missed cleaning up remote subtransaction at level %d",
1235 : entry->xact_depth);
1236 :
1237 28 : if (event == SUBXACT_EVENT_PRE_COMMIT_SUB)
1238 : {
1239 : /*
1240 : * If abort cleanup previously failed for this connection, we
1241 : * can't issue any more commands against it.
1242 : */
1243 14 : pgfdw_reject_incomplete_xact_state_change(entry);
1244 :
1245 : /* Commit all remote subtransactions during pre-commit */
1246 14 : snprintf(sql, sizeof(sql), "RELEASE SAVEPOINT s%d", curlevel);
1247 14 : entry->changing_xact_state = true;
1248 14 : if (entry->parallel_commit)
1249 : {
1250 4 : do_sql_command_begin(entry->conn, sql);
1251 4 : pending_entries = lappend(pending_entries, entry);
1252 4 : continue;
1253 : }
1254 10 : do_sql_command(entry->conn, sql);
1255 10 : entry->changing_xact_state = false;
1256 : }
1257 : else
1258 : {
1259 : /* Rollback all remote subtransactions during abort */
1260 14 : if (entry->parallel_abort)
1261 : {
1262 8 : if (pgfdw_abort_cleanup_begin(entry, false,
1263 : &pending_entries,
1264 : &cancel_requested))
1265 8 : continue;
1266 : }
1267 : else
1268 6 : pgfdw_abort_cleanup(entry, false);
1269 : }
1270 :
1271 : /* OK, we're outta that level of subtransaction */
1272 16 : pgfdw_reset_xact_state(entry, false);
1273 : }
1274 :
1275 : /* If there are any pending connections, finish cleaning them up */
1276 30 : if (pending_entries || cancel_requested)
1277 : {
1278 6 : if (event == SUBXACT_EVENT_PRE_COMMIT_SUB)
1279 : {
1280 : Assert(cancel_requested == NIL);
1281 2 : pgfdw_finish_pre_subcommit_cleanup(pending_entries, curlevel);
1282 : }
1283 : else
1284 : {
1285 : Assert(event == SUBXACT_EVENT_ABORT_SUB);
1286 4 : pgfdw_finish_abort_cleanup(pending_entries, cancel_requested,
1287 : false);
1288 : }
1289 : }
1290 : }
1291 :
1292 : /*
1293 : * Connection invalidation callback function
1294 : *
1295 : * After a change to a pg_foreign_server or pg_user_mapping catalog entry,
1296 : * close connections depending on that entry immediately if current transaction
1297 : * has not used those connections yet. Otherwise, mark those connections as
1298 : * invalid and then make pgfdw_xact_callback() close them at the end of current
1299 : * transaction, since they cannot be closed in the midst of the transaction
1300 : * using them. Closed connections will be remade at the next opportunity if
1301 : * necessary.
1302 : *
1303 : * Although most cache invalidation callbacks blow away all the related stuff
1304 : * regardless of the given hashvalue, connections are expensive enough that
1305 : * it's worth trying to avoid that.
1306 : *
1307 : * NB: We could avoid unnecessary disconnection more strictly by examining
1308 : * individual option values, but it seems too much effort for the gain.
1309 : */
1310 : static void
1311 344 : pgfdw_inval_callback(Datum arg, int cacheid, uint32 hashvalue)
1312 : {
1313 : HASH_SEQ_STATUS scan;
1314 : ConnCacheEntry *entry;
1315 :
1316 : Assert(cacheid == FOREIGNSERVEROID || cacheid == USERMAPPINGOID);
1317 :
1318 : /* ConnectionHash must exist already, if we're registered */
1319 344 : hash_seq_init(&scan, ConnectionHash);
1320 2332 : while ((entry = (ConnCacheEntry *) hash_seq_search(&scan)))
1321 : {
1322 : /* Ignore invalid entries */
1323 1988 : if (entry->conn == NULL)
1324 1624 : continue;
1325 :
1326 : /* hashvalue == 0 means a cache reset, must clear all state */
1327 364 : if (hashvalue == 0 ||
1328 258 : (cacheid == FOREIGNSERVEROID &&
1329 364 : entry->server_hashvalue == hashvalue) ||
1330 106 : (cacheid == USERMAPPINGOID &&
1331 106 : entry->mapping_hashvalue == hashvalue))
1332 : {
1333 : /*
1334 : * Close the connection immediately if it's not used yet in this
1335 : * transaction. Otherwise mark it as invalid so that
1336 : * pgfdw_xact_callback() can close it at the end of this
1337 : * transaction.
1338 : */
1339 98 : if (entry->xact_depth == 0)
1340 : {
1341 92 : elog(DEBUG3, "discarding connection %p", entry->conn);
1342 92 : disconnect_pg_server(entry);
1343 : }
1344 : else
1345 6 : entry->invalidated = true;
1346 : }
1347 : }
1348 344 : }
1349 :
1350 : /*
1351 : * Raise an error if the given connection cache entry is marked as being
1352 : * in the middle of an xact state change. This should be called at which no
1353 : * such change is expected to be in progress; if one is found to be in
1354 : * progress, it means that we aborted in the middle of a previous state change
1355 : * and now don't know what the remote transaction state actually is.
1356 : * Such connections can't safely be further used. Re-establishing the
1357 : * connection would change the snapshot and roll back any writes already
1358 : * performed, so that's not an option, either. Thus, we must abort.
1359 : */
1360 : static void
1361 5744 : pgfdw_reject_incomplete_xact_state_change(ConnCacheEntry *entry)
1362 : {
1363 : ForeignServer *server;
1364 :
1365 : /* nothing to do for inactive entries and entries of sane state */
1366 5744 : if (entry->conn == NULL || !entry->changing_xact_state)
1367 5744 : return;
1368 :
1369 : /* make sure this entry is inactive */
1370 0 : disconnect_pg_server(entry);
1371 :
1372 : /* find server name to be shown in the message below */
1373 0 : server = GetForeignServer(entry->serverid);
1374 :
1375 0 : ereport(ERROR,
1376 : (errcode(ERRCODE_CONNECTION_EXCEPTION),
1377 : errmsg("connection to server \"%s\" was lost",
1378 : server->servername)));
1379 : }
1380 :
1381 : /*
1382 : * Reset state to show we're out of a (sub)transaction.
1383 : */
1384 : static void
1385 2556 : pgfdw_reset_xact_state(ConnCacheEntry *entry, bool toplevel)
1386 : {
1387 2556 : if (toplevel)
1388 : {
1389 : /* Reset state to show we're out of a transaction */
1390 2528 : entry->xact_depth = 0;
1391 :
1392 : /*
1393 : * If the connection isn't in a good idle state, it is marked as
1394 : * invalid or keep_connections option of its server is disabled, then
1395 : * discard it to recover. Next GetConnection will open a new
1396 : * connection.
1397 : */
1398 5054 : if (PQstatus(entry->conn) != CONNECTION_OK ||
1399 2526 : PQtransactionStatus(entry->conn) != PQTRANS_IDLE ||
1400 2526 : entry->changing_xact_state ||
1401 2526 : entry->invalidated ||
1402 2522 : !entry->keep_connections)
1403 : {
1404 8 : elog(DEBUG3, "discarding connection %p", entry->conn);
1405 8 : disconnect_pg_server(entry);
1406 : }
1407 : }
1408 : else
1409 : {
1410 : /* Reset state to show we're out of a subtransaction */
1411 28 : entry->xact_depth--;
1412 : }
1413 2556 : }
1414 :
1415 : /*
1416 : * Cancel the currently-in-progress query (whose query text we do not have)
1417 : * and ignore the result. Returns true if we successfully cancel the query
1418 : * and discard any pending result, and false if not.
1419 : *
1420 : * It's not a huge problem if we throw an ERROR here, but if we get into error
1421 : * recursion trouble, we'll end up slamming the connection shut, which will
1422 : * necessitate failing the entire toplevel transaction even if subtransactions
1423 : * were used. Try to use WARNING where we can.
1424 : *
1425 : * XXX: if the query was one sent by fetch_more_data_begin(), we could get the
1426 : * query text from the pendingAreq saved in the per-connection state, then
1427 : * report the query using it.
1428 : */
1429 : static bool
1430 4 : pgfdw_cancel_query(PGconn *conn)
1431 : {
1432 4 : TimestampTz now = GetCurrentTimestamp();
1433 : TimestampTz endtime;
1434 : TimestampTz retrycanceltime;
1435 :
1436 : /*
1437 : * If it takes too long to cancel the query and discard the result, assume
1438 : * the connection is dead.
1439 : */
1440 4 : endtime = TimestampTzPlusMilliseconds(now, CONNECTION_CLEANUP_TIMEOUT);
1441 :
1442 : /*
1443 : * Also, lose patience and re-issue the cancel request after a little bit.
1444 : * (This serves to close some race conditions.)
1445 : */
1446 4 : retrycanceltime = TimestampTzPlusMilliseconds(now, RETRY_CANCEL_TIMEOUT);
1447 :
1448 4 : if (!pgfdw_cancel_query_begin(conn, endtime))
1449 0 : return false;
1450 4 : return pgfdw_cancel_query_end(conn, endtime, retrycanceltime, false);
1451 : }
1452 :
1453 : /*
1454 : * Submit a cancel request to the given connection, waiting only until
1455 : * the given time.
1456 : *
1457 : * We sleep interruptibly until we receive confirmation that the cancel
1458 : * request has been accepted, and if it is, return true; if the timeout
1459 : * lapses without that, or the request fails for whatever reason, return
1460 : * false.
1461 : */
1462 : static bool
1463 4 : pgfdw_cancel_query_begin(PGconn *conn, TimestampTz endtime)
1464 : {
1465 4 : const char *errormsg = libpqsrv_cancel(conn, endtime);
1466 :
1467 4 : if (errormsg != NULL)
1468 0 : ereport(WARNING,
1469 : errcode(ERRCODE_CONNECTION_FAILURE),
1470 : errmsg("could not send cancel request: %s", errormsg));
1471 :
1472 4 : return errormsg == NULL;
1473 : }
1474 :
1475 : static bool
1476 4 : pgfdw_cancel_query_end(PGconn *conn, TimestampTz endtime,
1477 : TimestampTz retrycanceltime, bool consume_input)
1478 : {
1479 : PGresult *result;
1480 : bool timed_out;
1481 :
1482 : /*
1483 : * If requested, consume whatever data is available from the socket. (Note
1484 : * that if all data is available, this allows pgfdw_get_cleanup_result to
1485 : * call PQgetResult without forcing the overhead of WaitLatchOrSocket,
1486 : * which would be large compared to the overhead of PQconsumeInput.)
1487 : */
1488 4 : if (consume_input && !PQconsumeInput(conn))
1489 : {
1490 0 : ereport(WARNING,
1491 : (errcode(ERRCODE_CONNECTION_FAILURE),
1492 : errmsg("could not get result of cancel request: %s",
1493 : pchomp(PQerrorMessage(conn)))));
1494 0 : return false;
1495 : }
1496 :
1497 : /* Get and discard the result of the query. */
1498 4 : if (pgfdw_get_cleanup_result(conn, endtime, retrycanceltime,
1499 : &result, &timed_out))
1500 : {
1501 0 : if (timed_out)
1502 0 : ereport(WARNING,
1503 : (errmsg("could not get result of cancel request due to timeout")));
1504 : else
1505 0 : ereport(WARNING,
1506 : (errcode(ERRCODE_CONNECTION_FAILURE),
1507 : errmsg("could not get result of cancel request: %s",
1508 : pchomp(PQerrorMessage(conn)))));
1509 :
1510 0 : return false;
1511 : }
1512 4 : PQclear(result);
1513 :
1514 4 : return true;
1515 : }
1516 :
1517 : /*
1518 : * Submit a query during (sub)abort cleanup and wait up to 30 seconds for the
1519 : * result. If the query is executed without error, the return value is true.
1520 : * If the query is executed successfully but returns an error, the return
1521 : * value is true if and only if ignore_errors is set. If the query can't be
1522 : * sent or times out, the return value is false.
1523 : *
1524 : * It's not a huge problem if we throw an ERROR here, but if we get into error
1525 : * recursion trouble, we'll end up slamming the connection shut, which will
1526 : * necessitate failing the entire toplevel transaction even if subtransactions
1527 : * were used. Try to use WARNING where we can.
1528 : */
1529 : static bool
1530 118 : pgfdw_exec_cleanup_query(PGconn *conn, const char *query, bool ignore_errors)
1531 : {
1532 : TimestampTz endtime;
1533 :
1534 : /*
1535 : * If it takes too long to execute a cleanup query, assume the connection
1536 : * is dead. It's fairly likely that this is why we aborted in the first
1537 : * place (e.g. statement timeout, user cancel), so the timeout shouldn't
1538 : * be too long.
1539 : */
1540 118 : endtime = TimestampTzPlusMilliseconds(GetCurrentTimestamp(),
1541 : CONNECTION_CLEANUP_TIMEOUT);
1542 :
1543 118 : if (!pgfdw_exec_cleanup_query_begin(conn, query))
1544 0 : return false;
1545 118 : return pgfdw_exec_cleanup_query_end(conn, query, endtime,
1546 : false, ignore_errors);
1547 : }
1548 :
1549 : static bool
1550 142 : pgfdw_exec_cleanup_query_begin(PGconn *conn, const char *query)
1551 : {
1552 : Assert(query != NULL);
1553 :
1554 : /*
1555 : * Submit a query. Since we don't use non-blocking mode, this also can
1556 : * block. But its risk is relatively small, so we ignore that for now.
1557 : */
1558 142 : if (!PQsendQuery(conn, query))
1559 : {
1560 0 : pgfdw_report(WARNING, NULL, conn, query);
1561 0 : return false;
1562 : }
1563 :
1564 142 : return true;
1565 : }
1566 :
1567 : static bool
1568 142 : pgfdw_exec_cleanup_query_end(PGconn *conn, const char *query,
1569 : TimestampTz endtime, bool consume_input,
1570 : bool ignore_errors)
1571 : {
1572 : PGresult *result;
1573 : bool timed_out;
1574 :
1575 : Assert(query != NULL);
1576 :
1577 : /*
1578 : * If requested, consume whatever data is available from the socket. (Note
1579 : * that if all data is available, this allows pgfdw_get_cleanup_result to
1580 : * call PQgetResult without forcing the overhead of WaitLatchOrSocket,
1581 : * which would be large compared to the overhead of PQconsumeInput.)
1582 : */
1583 142 : if (consume_input && !PQconsumeInput(conn))
1584 : {
1585 0 : pgfdw_report(WARNING, NULL, conn, query);
1586 0 : return false;
1587 : }
1588 :
1589 : /* Get the result of the query. */
1590 142 : if (pgfdw_get_cleanup_result(conn, endtime, endtime, &result, &timed_out))
1591 : {
1592 0 : if (timed_out)
1593 0 : ereport(WARNING,
1594 : (errmsg("could not get query result due to timeout"),
1595 : errcontext("remote SQL command: %s", query)));
1596 : else
1597 0 : pgfdw_report(WARNING, NULL, conn, query);
1598 :
1599 0 : return false;
1600 : }
1601 :
1602 : /* Issue a warning if not successful. */
1603 142 : if (PQresultStatus(result) != PGRES_COMMAND_OK)
1604 : {
1605 0 : pgfdw_report(WARNING, result, conn, query);
1606 0 : return ignore_errors;
1607 : }
1608 142 : PQclear(result);
1609 :
1610 142 : return true;
1611 : }
1612 :
1613 : /*
1614 : * Get, during abort cleanup, the result of a query that is in progress.
1615 : * This might be a query that is being interrupted by a cancel request or by
1616 : * transaction abort, or it might be a query that was initiated as part of
1617 : * transaction abort to get the remote side back to the appropriate state.
1618 : *
1619 : * endtime is the time at which we should give up and assume the remote side
1620 : * is dead. retrycanceltime is the time at which we should issue a fresh
1621 : * cancel request (pass the same value as endtime if this is not wanted).
1622 : *
1623 : * Returns true if the timeout expired or connection trouble occurred,
1624 : * false otherwise. Sets *result except in case of a true result.
1625 : * Sets *timed_out to true only when the timeout expired.
1626 : */
1627 : static bool
1628 146 : pgfdw_get_cleanup_result(PGconn *conn, TimestampTz endtime,
1629 : TimestampTz retrycanceltime,
1630 : PGresult **result,
1631 : bool *timed_out)
1632 : {
1633 146 : bool failed = false;
1634 146 : PGresult *last_res = NULL;
1635 146 : int canceldelta = RETRY_CANCEL_TIMEOUT * 2;
1636 :
1637 146 : *result = NULL;
1638 146 : *timed_out = false;
1639 : for (;;)
1640 160 : {
1641 : PGresult *res;
1642 :
1643 446 : while (PQisBusy(conn))
1644 : {
1645 : int wc;
1646 140 : TimestampTz now = GetCurrentTimestamp();
1647 : long cur_timeout;
1648 :
1649 : /* If timeout has expired, give up. */
1650 140 : if (now >= endtime)
1651 : {
1652 0 : *timed_out = true;
1653 0 : failed = true;
1654 0 : goto exit;
1655 : }
1656 :
1657 : /* If we need to re-issue the cancel request, do that. */
1658 140 : if (now >= retrycanceltime)
1659 : {
1660 : /* We ignore failure to issue the repeated request. */
1661 0 : (void) libpqsrv_cancel(conn, endtime);
1662 :
1663 : /* Recompute "now" in case that took measurable time. */
1664 0 : now = GetCurrentTimestamp();
1665 :
1666 : /* Adjust re-cancel timeout in increasing steps. */
1667 0 : retrycanceltime = TimestampTzPlusMilliseconds(now,
1668 : canceldelta);
1669 0 : canceldelta += canceldelta;
1670 : }
1671 :
1672 : /* If timeout has expired, give up, else get sleep time. */
1673 140 : cur_timeout = TimestampDifferenceMilliseconds(now,
1674 : Min(endtime,
1675 : retrycanceltime));
1676 140 : if (cur_timeout <= 0)
1677 : {
1678 0 : *timed_out = true;
1679 0 : failed = true;
1680 0 : goto exit;
1681 : }
1682 :
1683 : /* first time, allocate or get the custom wait event */
1684 140 : if (pgfdw_we_cleanup_result == 0)
1685 4 : pgfdw_we_cleanup_result = WaitEventExtensionNew("PostgresFdwCleanupResult");
1686 :
1687 : /* Sleep until there's something to do */
1688 140 : wc = WaitLatchOrSocket(MyLatch,
1689 : WL_LATCH_SET | WL_SOCKET_READABLE |
1690 : WL_TIMEOUT | WL_EXIT_ON_PM_DEATH,
1691 : PQsocket(conn),
1692 : cur_timeout, pgfdw_we_cleanup_result);
1693 140 : ResetLatch(MyLatch);
1694 :
1695 140 : CHECK_FOR_INTERRUPTS();
1696 :
1697 : /* Data available in socket? */
1698 140 : if (wc & WL_SOCKET_READABLE)
1699 : {
1700 140 : if (!PQconsumeInput(conn))
1701 : {
1702 : /* connection trouble */
1703 0 : failed = true;
1704 0 : goto exit;
1705 : }
1706 : }
1707 : }
1708 :
1709 306 : res = PQgetResult(conn);
1710 306 : if (res == NULL)
1711 146 : break; /* query is complete */
1712 :
1713 160 : PQclear(last_res);
1714 160 : last_res = res;
1715 : }
1716 146 : exit:
1717 146 : if (failed)
1718 0 : PQclear(last_res);
1719 : else
1720 146 : *result = last_res;
1721 146 : return failed;
1722 : }
1723 :
1724 : /*
1725 : * Abort remote transaction or subtransaction.
1726 : *
1727 : * "toplevel" should be set to true if toplevel (main) transaction is
1728 : * rollbacked, false otherwise.
1729 : *
1730 : * Set entry->changing_xact_state to false on success, true on failure.
1731 : */
1732 : static void
1733 86 : pgfdw_abort_cleanup(ConnCacheEntry *entry, bool toplevel)
1734 : {
1735 : char sql[100];
1736 :
1737 : /*
1738 : * Don't try to clean up the connection if we're already in error
1739 : * recursion trouble.
1740 : */
1741 86 : if (in_error_recursion_trouble())
1742 0 : entry->changing_xact_state = true;
1743 :
1744 : /*
1745 : * If connection is already unsalvageable, don't touch it further.
1746 : */
1747 86 : if (entry->changing_xact_state)
1748 2 : return;
1749 :
1750 : /*
1751 : * Mark this connection as in the process of changing transaction state.
1752 : */
1753 84 : entry->changing_xact_state = true;
1754 :
1755 : /* Assume we might have lost track of prepared statements */
1756 84 : entry->have_error = true;
1757 :
1758 : /*
1759 : * If a command has been submitted to the remote server by using an
1760 : * asynchronous execution function, the command might not have yet
1761 : * completed. Check to see if a command is still being processed by the
1762 : * remote server, and if so, request cancellation of the command.
1763 : */
1764 84 : if (PQtransactionStatus(entry->conn) == PQTRANS_ACTIVE &&
1765 4 : !pgfdw_cancel_query(entry->conn))
1766 0 : return; /* Unable to cancel running query */
1767 :
1768 84 : CONSTRUCT_ABORT_COMMAND(sql, entry, toplevel);
1769 84 : if (!pgfdw_exec_cleanup_query(entry->conn, sql, false))
1770 0 : return; /* Unable to abort remote (sub)transaction */
1771 :
1772 84 : if (toplevel)
1773 : {
1774 78 : if (entry->have_prep_stmt && entry->have_error &&
1775 34 : !pgfdw_exec_cleanup_query(entry->conn,
1776 : "DEALLOCATE ALL",
1777 : true))
1778 0 : return; /* Trouble clearing prepared statements */
1779 :
1780 78 : entry->have_prep_stmt = false;
1781 78 : entry->have_error = false;
1782 : }
1783 :
1784 : /*
1785 : * If pendingAreq of the per-connection state is not NULL, it means that
1786 : * an asynchronous fetch begun by fetch_more_data_begin() was not done
1787 : * successfully and thus the per-connection state was not reset in
1788 : * fetch_more_data(); in that case reset the per-connection state here.
1789 : */
1790 84 : if (entry->state.pendingAreq)
1791 2 : memset(&entry->state, 0, sizeof(entry->state));
1792 :
1793 : /* Disarm changing_xact_state if it all worked */
1794 84 : entry->changing_xact_state = false;
1795 : }
1796 :
1797 : /*
1798 : * Like pgfdw_abort_cleanup, submit an abort command or cancel request, but
1799 : * don't wait for the result.
1800 : *
1801 : * Returns true if the abort command or cancel request is successfully issued,
1802 : * false otherwise. If the abort command is successfully issued, the given
1803 : * connection cache entry is appended to *pending_entries. Otherwise, if the
1804 : * cancel request is successfully issued, it is appended to *cancel_requested.
1805 : */
1806 : static bool
1807 16 : pgfdw_abort_cleanup_begin(ConnCacheEntry *entry, bool toplevel,
1808 : List **pending_entries, List **cancel_requested)
1809 : {
1810 : /*
1811 : * Don't try to clean up the connection if we're already in error
1812 : * recursion trouble.
1813 : */
1814 16 : if (in_error_recursion_trouble())
1815 0 : entry->changing_xact_state = true;
1816 :
1817 : /*
1818 : * If connection is already unsalvageable, don't touch it further.
1819 : */
1820 16 : if (entry->changing_xact_state)
1821 0 : return false;
1822 :
1823 : /*
1824 : * Mark this connection as in the process of changing transaction state.
1825 : */
1826 16 : entry->changing_xact_state = true;
1827 :
1828 : /* Assume we might have lost track of prepared statements */
1829 16 : entry->have_error = true;
1830 :
1831 : /*
1832 : * If a command has been submitted to the remote server by using an
1833 : * asynchronous execution function, the command might not have yet
1834 : * completed. Check to see if a command is still being processed by the
1835 : * remote server, and if so, request cancellation of the command.
1836 : */
1837 16 : if (PQtransactionStatus(entry->conn) == PQTRANS_ACTIVE)
1838 : {
1839 : TimestampTz endtime;
1840 :
1841 0 : endtime = TimestampTzPlusMilliseconds(GetCurrentTimestamp(),
1842 : CONNECTION_CLEANUP_TIMEOUT);
1843 0 : if (!pgfdw_cancel_query_begin(entry->conn, endtime))
1844 0 : return false; /* Unable to cancel running query */
1845 0 : *cancel_requested = lappend(*cancel_requested, entry);
1846 : }
1847 : else
1848 : {
1849 : char sql[100];
1850 :
1851 16 : CONSTRUCT_ABORT_COMMAND(sql, entry, toplevel);
1852 16 : if (!pgfdw_exec_cleanup_query_begin(entry->conn, sql))
1853 0 : return false; /* Unable to abort remote transaction */
1854 16 : *pending_entries = lappend(*pending_entries, entry);
1855 : }
1856 :
1857 16 : return true;
1858 : }
1859 :
1860 : /*
1861 : * Finish pre-commit cleanup of connections on each of which we've sent a
1862 : * COMMIT command to the remote server.
1863 : */
1864 : static void
1865 26 : pgfdw_finish_pre_commit_cleanup(List *pending_entries)
1866 : {
1867 : ConnCacheEntry *entry;
1868 26 : List *pending_deallocs = NIL;
1869 : ListCell *lc;
1870 :
1871 : Assert(pending_entries);
1872 :
1873 : /*
1874 : * Get the result of the COMMIT command for each of the pending entries
1875 : */
1876 58 : foreach(lc, pending_entries)
1877 : {
1878 32 : entry = (ConnCacheEntry *) lfirst(lc);
1879 :
1880 : Assert(entry->changing_xact_state);
1881 :
1882 : /*
1883 : * We might already have received the result on the socket, so pass
1884 : * consume_input=true to try to consume it first
1885 : */
1886 32 : do_sql_command_end(entry->conn, "COMMIT TRANSACTION", true);
1887 32 : entry->changing_xact_state = false;
1888 :
1889 : /* Do a DEALLOCATE ALL in parallel if needed */
1890 32 : if (entry->have_prep_stmt && entry->have_error)
1891 : {
1892 : /* Ignore errors (see notes in pgfdw_xact_callback) */
1893 4 : if (PQsendQuery(entry->conn, "DEALLOCATE ALL"))
1894 : {
1895 4 : pending_deallocs = lappend(pending_deallocs, entry);
1896 4 : continue;
1897 : }
1898 : }
1899 28 : entry->have_prep_stmt = false;
1900 28 : entry->have_error = false;
1901 :
1902 28 : pgfdw_reset_xact_state(entry, true);
1903 : }
1904 :
1905 : /* No further work if no pending entries */
1906 26 : if (!pending_deallocs)
1907 24 : return;
1908 :
1909 : /*
1910 : * Get the result of the DEALLOCATE command for each of the pending
1911 : * entries
1912 : */
1913 6 : foreach(lc, pending_deallocs)
1914 : {
1915 : PGresult *res;
1916 :
1917 4 : entry = (ConnCacheEntry *) lfirst(lc);
1918 :
1919 : /* Ignore errors (see notes in pgfdw_xact_callback) */
1920 8 : while ((res = PQgetResult(entry->conn)) != NULL)
1921 : {
1922 4 : PQclear(res);
1923 : /* Stop if the connection is lost (else we'll loop infinitely) */
1924 4 : if (PQstatus(entry->conn) == CONNECTION_BAD)
1925 0 : break;
1926 : }
1927 4 : entry->have_prep_stmt = false;
1928 4 : entry->have_error = false;
1929 :
1930 4 : pgfdw_reset_xact_state(entry, true);
1931 : }
1932 : }
1933 :
1934 : /*
1935 : * Finish pre-subcommit cleanup of connections on each of which we've sent a
1936 : * RELEASE command to the remote server.
1937 : */
1938 : static void
1939 2 : pgfdw_finish_pre_subcommit_cleanup(List *pending_entries, int curlevel)
1940 : {
1941 : ConnCacheEntry *entry;
1942 : char sql[100];
1943 : ListCell *lc;
1944 :
1945 : Assert(pending_entries);
1946 :
1947 : /*
1948 : * Get the result of the RELEASE command for each of the pending entries
1949 : */
1950 2 : snprintf(sql, sizeof(sql), "RELEASE SAVEPOINT s%d", curlevel);
1951 6 : foreach(lc, pending_entries)
1952 : {
1953 4 : entry = (ConnCacheEntry *) lfirst(lc);
1954 :
1955 : Assert(entry->changing_xact_state);
1956 :
1957 : /*
1958 : * We might already have received the result on the socket, so pass
1959 : * consume_input=true to try to consume it first
1960 : */
1961 4 : do_sql_command_end(entry->conn, sql, true);
1962 4 : entry->changing_xact_state = false;
1963 :
1964 4 : pgfdw_reset_xact_state(entry, false);
1965 : }
1966 2 : }
1967 :
1968 : /*
1969 : * Finish abort cleanup of connections on each of which we've sent an abort
1970 : * command or cancel request to the remote server.
1971 : */
1972 : static void
1973 8 : pgfdw_finish_abort_cleanup(List *pending_entries, List *cancel_requested,
1974 : bool toplevel)
1975 : {
1976 8 : List *pending_deallocs = NIL;
1977 : ListCell *lc;
1978 :
1979 : /*
1980 : * For each of the pending cancel requests (if any), get and discard the
1981 : * result of the query, and submit an abort command to the remote server.
1982 : */
1983 8 : if (cancel_requested)
1984 : {
1985 0 : foreach(lc, cancel_requested)
1986 : {
1987 0 : ConnCacheEntry *entry = (ConnCacheEntry *) lfirst(lc);
1988 0 : TimestampTz now = GetCurrentTimestamp();
1989 : TimestampTz endtime;
1990 : TimestampTz retrycanceltime;
1991 : char sql[100];
1992 :
1993 : Assert(entry->changing_xact_state);
1994 :
1995 : /*
1996 : * Set end time. You might think we should do this before issuing
1997 : * cancel request like in normal mode, but that is problematic,
1998 : * because if, for example, it took longer than 30 seconds to
1999 : * process the first few entries in the cancel_requested list, it
2000 : * would cause a timeout error when processing each of the
2001 : * remaining entries in the list, leading to slamming that entry's
2002 : * connection shut.
2003 : */
2004 0 : endtime = TimestampTzPlusMilliseconds(now,
2005 : CONNECTION_CLEANUP_TIMEOUT);
2006 0 : retrycanceltime = TimestampTzPlusMilliseconds(now,
2007 : RETRY_CANCEL_TIMEOUT);
2008 :
2009 0 : if (!pgfdw_cancel_query_end(entry->conn, endtime,
2010 : retrycanceltime, true))
2011 : {
2012 : /* Unable to cancel running query */
2013 0 : pgfdw_reset_xact_state(entry, toplevel);
2014 0 : continue;
2015 : }
2016 :
2017 : /* Send an abort command in parallel if needed */
2018 0 : CONSTRUCT_ABORT_COMMAND(sql, entry, toplevel);
2019 0 : if (!pgfdw_exec_cleanup_query_begin(entry->conn, sql))
2020 : {
2021 : /* Unable to abort remote (sub)transaction */
2022 0 : pgfdw_reset_xact_state(entry, toplevel);
2023 : }
2024 : else
2025 0 : pending_entries = lappend(pending_entries, entry);
2026 : }
2027 : }
2028 :
2029 : /* No further work if no pending entries */
2030 8 : if (!pending_entries)
2031 0 : return;
2032 :
2033 : /*
2034 : * Get the result of the abort command for each of the pending entries
2035 : */
2036 24 : foreach(lc, pending_entries)
2037 : {
2038 16 : ConnCacheEntry *entry = (ConnCacheEntry *) lfirst(lc);
2039 : TimestampTz endtime;
2040 : char sql[100];
2041 :
2042 : Assert(entry->changing_xact_state);
2043 :
2044 : /*
2045 : * Set end time. We do this now, not before issuing the command like
2046 : * in normal mode, for the same reason as for the cancel_requested
2047 : * entries.
2048 : */
2049 16 : endtime = TimestampTzPlusMilliseconds(GetCurrentTimestamp(),
2050 : CONNECTION_CLEANUP_TIMEOUT);
2051 :
2052 16 : CONSTRUCT_ABORT_COMMAND(sql, entry, toplevel);
2053 16 : if (!pgfdw_exec_cleanup_query_end(entry->conn, sql, endtime,
2054 : true, false))
2055 : {
2056 : /* Unable to abort remote (sub)transaction */
2057 0 : pgfdw_reset_xact_state(entry, toplevel);
2058 8 : continue;
2059 : }
2060 :
2061 16 : if (toplevel)
2062 : {
2063 : /* Do a DEALLOCATE ALL in parallel if needed */
2064 8 : if (entry->have_prep_stmt && entry->have_error)
2065 : {
2066 8 : if (!pgfdw_exec_cleanup_query_begin(entry->conn,
2067 : "DEALLOCATE ALL"))
2068 : {
2069 : /* Trouble clearing prepared statements */
2070 0 : pgfdw_reset_xact_state(entry, toplevel);
2071 : }
2072 : else
2073 8 : pending_deallocs = lappend(pending_deallocs, entry);
2074 8 : continue;
2075 : }
2076 0 : entry->have_prep_stmt = false;
2077 0 : entry->have_error = false;
2078 : }
2079 :
2080 : /* Reset the per-connection state if needed */
2081 8 : if (entry->state.pendingAreq)
2082 0 : memset(&entry->state, 0, sizeof(entry->state));
2083 :
2084 : /* We're done with this entry; unset the changing_xact_state flag */
2085 8 : entry->changing_xact_state = false;
2086 8 : pgfdw_reset_xact_state(entry, toplevel);
2087 : }
2088 :
2089 : /* No further work if no pending entries */
2090 8 : if (!pending_deallocs)
2091 4 : return;
2092 : Assert(toplevel);
2093 :
2094 : /*
2095 : * Get the result of the DEALLOCATE command for each of the pending
2096 : * entries
2097 : */
2098 12 : foreach(lc, pending_deallocs)
2099 : {
2100 8 : ConnCacheEntry *entry = (ConnCacheEntry *) lfirst(lc);
2101 : TimestampTz endtime;
2102 :
2103 : Assert(entry->changing_xact_state);
2104 : Assert(entry->have_prep_stmt);
2105 : Assert(entry->have_error);
2106 :
2107 : /*
2108 : * Set end time. We do this now, not before issuing the command like
2109 : * in normal mode, for the same reason as for the cancel_requested
2110 : * entries.
2111 : */
2112 8 : endtime = TimestampTzPlusMilliseconds(GetCurrentTimestamp(),
2113 : CONNECTION_CLEANUP_TIMEOUT);
2114 :
2115 8 : if (!pgfdw_exec_cleanup_query_end(entry->conn, "DEALLOCATE ALL",
2116 : endtime, true, true))
2117 : {
2118 : /* Trouble clearing prepared statements */
2119 0 : pgfdw_reset_xact_state(entry, toplevel);
2120 0 : continue;
2121 : }
2122 8 : entry->have_prep_stmt = false;
2123 8 : entry->have_error = false;
2124 :
2125 : /* Reset the per-connection state if needed */
2126 8 : if (entry->state.pendingAreq)
2127 0 : memset(&entry->state, 0, sizeof(entry->state));
2128 :
2129 : /* We're done with this entry; unset the changing_xact_state flag */
2130 8 : entry->changing_xact_state = false;
2131 8 : pgfdw_reset_xact_state(entry, toplevel);
2132 : }
2133 : }
2134 :
2135 : /* Number of output arguments (columns) for various API versions */
2136 : #define POSTGRES_FDW_GET_CONNECTIONS_COLS_V1_1 2
2137 : #define POSTGRES_FDW_GET_CONNECTIONS_COLS_V1_2 6
2138 : #define POSTGRES_FDW_GET_CONNECTIONS_COLS 6 /* maximum of above */
2139 :
2140 : /*
2141 : * Internal function used by postgres_fdw_get_connections variants.
2142 : *
2143 : * For API version 1.1, this function takes no input parameter and
2144 : * returns a set of records with the following values:
2145 : *
2146 : * - server_name - server name of active connection. In case the foreign server
2147 : * is dropped but still the connection is active, then the server name will
2148 : * be NULL in output.
2149 : * - valid - true/false representing whether the connection is valid or not.
2150 : * Note that connections can become invalid in pgfdw_inval_callback.
2151 : *
2152 : * For API version 1.2 and later, this function takes an input parameter
2153 : * to check a connection status and returns the following
2154 : * additional values along with the four values from version 1.1:
2155 : *
2156 : * - user_name - the local user name of the active connection. In case the
2157 : * user mapping is dropped but the connection is still active, then the
2158 : * user name will be NULL in the output.
2159 : * - used_in_xact - true if the connection is used in the current transaction.
2160 : * - closed - true if the connection is closed.
2161 : * - remote_backend_pid - process ID of the remote backend, on the foreign
2162 : * server, handling the connection.
2163 : *
2164 : * No records are returned when there are no cached connections at all.
2165 : */
2166 : static void
2167 26 : postgres_fdw_get_connections_internal(FunctionCallInfo fcinfo,
2168 : enum pgfdwVersion api_version)
2169 : {
2170 26 : ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
2171 : HASH_SEQ_STATUS scan;
2172 : ConnCacheEntry *entry;
2173 :
2174 26 : InitMaterializedSRF(fcinfo, 0);
2175 :
2176 : /* If cache doesn't exist, we return no records */
2177 26 : if (!ConnectionHash)
2178 0 : return;
2179 :
2180 : /* Check we have the expected number of output arguments */
2181 26 : switch (rsinfo->setDesc->natts)
2182 : {
2183 0 : case POSTGRES_FDW_GET_CONNECTIONS_COLS_V1_1:
2184 0 : if (api_version != PGFDW_V1_1)
2185 0 : elog(ERROR, "incorrect number of output arguments");
2186 0 : break;
2187 26 : case POSTGRES_FDW_GET_CONNECTIONS_COLS_V1_2:
2188 26 : if (api_version != PGFDW_V1_2)
2189 0 : elog(ERROR, "incorrect number of output arguments");
2190 26 : break;
2191 0 : default:
2192 0 : elog(ERROR, "incorrect number of output arguments");
2193 : }
2194 :
2195 26 : hash_seq_init(&scan, ConnectionHash);
2196 226 : while ((entry = (ConnCacheEntry *) hash_seq_search(&scan)))
2197 : {
2198 : ForeignServer *server;
2199 200 : Datum values[POSTGRES_FDW_GET_CONNECTIONS_COLS] = {0};
2200 200 : bool nulls[POSTGRES_FDW_GET_CONNECTIONS_COLS] = {0};
2201 200 : int i = 0;
2202 :
2203 : /* We only look for open remote connections */
2204 200 : if (!entry->conn)
2205 174 : continue;
2206 :
2207 26 : server = GetForeignServerExtended(entry->serverid, FSV_MISSING_OK);
2208 :
2209 : /*
2210 : * The foreign server may have been dropped in current explicit
2211 : * transaction. It is not possible to drop the server from another
2212 : * session when the connection associated with it is in use in the
2213 : * current transaction, if tried so, the drop query in another session
2214 : * blocks until the current transaction finishes.
2215 : *
2216 : * Even though the server is dropped in the current transaction, the
2217 : * cache can still have associated active connection entry, say we
2218 : * call such connections dangling. Since we can not fetch the server
2219 : * name from system catalogs for dangling connections, instead we show
2220 : * NULL value for server name in output.
2221 : *
2222 : * We could have done better by storing the server name in the cache
2223 : * entry instead of server oid so that it could be used in the output.
2224 : * But the server name in each cache entry requires 64 bytes of
2225 : * memory, which is huge, when there are many cached connections and
2226 : * the use case i.e. dropping the foreign server within the explicit
2227 : * current transaction seems rare. So, we chose to show NULL value for
2228 : * server name in output.
2229 : *
2230 : * Such dangling connections get closed either in next use or at the
2231 : * end of current explicit transaction in pgfdw_xact_callback.
2232 : */
2233 26 : if (!server)
2234 : {
2235 : /*
2236 : * If the server has been dropped in the current explicit
2237 : * transaction, then this entry would have been invalidated in
2238 : * pgfdw_inval_callback at the end of drop server command. Note
2239 : * that this connection would not have been closed in
2240 : * pgfdw_inval_callback because it is still being used in the
2241 : * current explicit transaction. So, assert that here.
2242 : */
2243 : Assert(entry->conn && entry->xact_depth > 0 && entry->invalidated);
2244 :
2245 : /* Show null, if no server name was found */
2246 2 : nulls[i++] = true;
2247 : }
2248 : else
2249 24 : values[i++] = CStringGetTextDatum(server->servername);
2250 :
2251 26 : if (api_version >= PGFDW_V1_2)
2252 : {
2253 : HeapTuple tp;
2254 :
2255 : /* Use the system cache to obtain the user mapping */
2256 26 : tp = SearchSysCache1(USERMAPPINGOID, ObjectIdGetDatum(entry->key));
2257 :
2258 : /*
2259 : * Just like in the foreign server case, user mappings can also be
2260 : * dropped in the current explicit transaction. Therefore, the
2261 : * similar check as in the server case is required.
2262 : */
2263 26 : if (!HeapTupleIsValid(tp))
2264 : {
2265 : /*
2266 : * If we reach here, this entry must have been invalidated in
2267 : * pgfdw_inval_callback, same as in the server case.
2268 : */
2269 : Assert(entry->conn && entry->xact_depth > 0 &&
2270 : entry->invalidated);
2271 :
2272 2 : nulls[i++] = true;
2273 : }
2274 : else
2275 : {
2276 : Oid userid;
2277 :
2278 24 : userid = ((Form_pg_user_mapping) GETSTRUCT(tp))->umuser;
2279 24 : values[i++] = CStringGetTextDatum(MappingUserName(userid));
2280 24 : ReleaseSysCache(tp);
2281 : }
2282 : }
2283 :
2284 26 : values[i++] = BoolGetDatum(!entry->invalidated);
2285 :
2286 26 : if (api_version >= PGFDW_V1_2)
2287 : {
2288 26 : bool check_conn = PG_GETARG_BOOL(0);
2289 :
2290 : /* Is this connection used in the current transaction? */
2291 26 : values[i++] = BoolGetDatum(entry->xact_depth > 0);
2292 :
2293 : /*
2294 : * If a connection status check is requested and supported, return
2295 : * whether the connection is closed. Otherwise, return NULL.
2296 : */
2297 26 : if (check_conn && pgfdw_conn_checkable())
2298 4 : values[i++] = BoolGetDatum(pgfdw_conn_check(entry->conn) != 0);
2299 : else
2300 22 : nulls[i++] = true;
2301 :
2302 : /* Return process ID of remote backend */
2303 26 : values[i++] = Int32GetDatum(PQbackendPID(entry->conn));
2304 : }
2305 :
2306 26 : tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
2307 : }
2308 : }
2309 :
2310 : /*
2311 : * List active foreign server connections.
2312 : *
2313 : * The SQL API of this function has changed multiple times, and will likely
2314 : * do so again in future. To support the case where a newer version of this
2315 : * loadable module is being used with an old SQL declaration of the function,
2316 : * we continue to support the older API versions.
2317 : */
2318 : Datum
2319 26 : postgres_fdw_get_connections_1_2(PG_FUNCTION_ARGS)
2320 : {
2321 26 : postgres_fdw_get_connections_internal(fcinfo, PGFDW_V1_2);
2322 :
2323 26 : PG_RETURN_VOID();
2324 : }
2325 :
2326 : Datum
2327 0 : postgres_fdw_get_connections(PG_FUNCTION_ARGS)
2328 : {
2329 0 : postgres_fdw_get_connections_internal(fcinfo, PGFDW_V1_1);
2330 :
2331 0 : PG_RETURN_VOID();
2332 : }
2333 :
2334 : /*
2335 : * Disconnect the specified cached connections.
2336 : *
2337 : * This function discards the open connections that are established by
2338 : * postgres_fdw from the local session to the foreign server with
2339 : * the given name. Note that there can be multiple connections to
2340 : * the given server using different user mappings. If the connections
2341 : * are used in the current local transaction, they are not disconnected
2342 : * and warning messages are reported. This function returns true
2343 : * if it disconnects at least one connection, otherwise false. If no
2344 : * foreign server with the given name is found, an error is reported.
2345 : */
2346 : Datum
2347 8 : postgres_fdw_disconnect(PG_FUNCTION_ARGS)
2348 : {
2349 : ForeignServer *server;
2350 : char *servername;
2351 :
2352 8 : servername = text_to_cstring(PG_GETARG_TEXT_PP(0));
2353 8 : server = GetForeignServerByName(servername, false);
2354 :
2355 6 : PG_RETURN_BOOL(disconnect_cached_connections(server->serverid));
2356 : }
2357 :
2358 : /*
2359 : * Disconnect all the cached connections.
2360 : *
2361 : * This function discards all the open connections that are established by
2362 : * postgres_fdw from the local session to the foreign servers.
2363 : * If the connections are used in the current local transaction, they are
2364 : * not disconnected and warning messages are reported. This function
2365 : * returns true if it disconnects at least one connection, otherwise false.
2366 : */
2367 : Datum
2368 10 : postgres_fdw_disconnect_all(PG_FUNCTION_ARGS)
2369 : {
2370 10 : PG_RETURN_BOOL(disconnect_cached_connections(InvalidOid));
2371 : }
2372 :
2373 : /*
2374 : * Workhorse to disconnect cached connections.
2375 : *
2376 : * This function scans all the connection cache entries and disconnects
2377 : * the open connections whose foreign server OID matches with
2378 : * the specified one. If InvalidOid is specified, it disconnects all
2379 : * the cached connections.
2380 : *
2381 : * This function emits a warning for each connection that's used in
2382 : * the current transaction and doesn't close it. It returns true if
2383 : * it disconnects at least one connection, otherwise false.
2384 : *
2385 : * Note that this function disconnects even the connections that are
2386 : * established by other users in the same local session using different
2387 : * user mappings. This leads even non-superuser to be able to close
2388 : * the connections established by superusers in the same local session.
2389 : *
2390 : * XXX As of now we don't see any security risk doing this. But we should
2391 : * set some restrictions on that, for example, prevent non-superuser
2392 : * from closing the connections established by superusers even
2393 : * in the same session?
2394 : */
2395 : static bool
2396 16 : disconnect_cached_connections(Oid serverid)
2397 : {
2398 : HASH_SEQ_STATUS scan;
2399 : ConnCacheEntry *entry;
2400 16 : bool all = !OidIsValid(serverid);
2401 16 : bool result = false;
2402 :
2403 : /*
2404 : * Connection cache hashtable has not been initialized yet in this
2405 : * session, so return false.
2406 : */
2407 16 : if (!ConnectionHash)
2408 0 : return false;
2409 :
2410 16 : hash_seq_init(&scan, ConnectionHash);
2411 134 : while ((entry = (ConnCacheEntry *) hash_seq_search(&scan)))
2412 : {
2413 : /* Ignore cache entry if no open connection right now. */
2414 118 : if (!entry->conn)
2415 96 : continue;
2416 :
2417 22 : if (all || entry->serverid == serverid)
2418 : {
2419 : /*
2420 : * Emit a warning because the connection to close is used in the
2421 : * current transaction and cannot be disconnected right now.
2422 : */
2423 16 : if (entry->xact_depth > 0)
2424 : {
2425 : ForeignServer *server;
2426 :
2427 6 : server = GetForeignServerExtended(entry->serverid,
2428 : FSV_MISSING_OK);
2429 :
2430 6 : if (!server)
2431 : {
2432 : /*
2433 : * If the foreign server was dropped while its connection
2434 : * was used in the current transaction, the connection
2435 : * must have been marked as invalid by
2436 : * pgfdw_inval_callback at the end of DROP SERVER command.
2437 : */
2438 : Assert(entry->invalidated);
2439 :
2440 0 : ereport(WARNING,
2441 : (errmsg("cannot close dropped server connection because it is still in use")));
2442 : }
2443 : else
2444 6 : ereport(WARNING,
2445 : (errmsg("cannot close connection for server \"%s\" because it is still in use",
2446 : server->servername)));
2447 : }
2448 : else
2449 : {
2450 10 : elog(DEBUG3, "discarding connection %p", entry->conn);
2451 10 : disconnect_pg_server(entry);
2452 10 : result = true;
2453 : }
2454 : }
2455 : }
2456 :
2457 16 : return result;
2458 : }
2459 :
2460 : /*
2461 : * Check if the remote server closed the connection.
2462 : *
2463 : * Returns 1 if the connection is closed, -1 if an error occurred,
2464 : * and 0 if it's not closed or if the connection check is unavailable
2465 : * on this platform.
2466 : */
2467 : static int
2468 4 : pgfdw_conn_check(PGconn *conn)
2469 : {
2470 4 : int sock = PQsocket(conn);
2471 :
2472 4 : if (PQstatus(conn) != CONNECTION_OK || sock == -1)
2473 0 : return -1;
2474 :
2475 : #if (defined(HAVE_POLL) && defined(POLLRDHUP))
2476 : {
2477 : struct pollfd input_fd;
2478 : int result;
2479 :
2480 4 : input_fd.fd = sock;
2481 4 : input_fd.events = POLLRDHUP;
2482 4 : input_fd.revents = 0;
2483 :
2484 : do
2485 4 : result = poll(&input_fd, 1, 0);
2486 4 : while (result < 0 && errno == EINTR);
2487 :
2488 4 : if (result < 0)
2489 0 : return -1;
2490 :
2491 4 : return (input_fd.revents &
2492 4 : (POLLRDHUP | POLLHUP | POLLERR | POLLNVAL)) ? 1 : 0;
2493 : }
2494 : #else
2495 : return 0;
2496 : #endif
2497 : }
2498 :
2499 : /*
2500 : * Check if connection status checking is available on this platform.
2501 : *
2502 : * Returns true if available, false otherwise.
2503 : */
2504 : static bool
2505 4 : pgfdw_conn_checkable(void)
2506 : {
2507 : #if (defined(HAVE_POLL) && defined(POLLRDHUP))
2508 4 : return true;
2509 : #else
2510 : return false;
2511 : #endif
2512 : }
2513 :
2514 : /*
2515 : * Ensure that require_auth and SCRAM keys are correctly set on values. SCRAM
2516 : * keys used to pass-through are coming from the initial connection from the
2517 : * client with the server.
2518 : *
2519 : * All required SCRAM options are set by postgres_fdw, so we just need to
2520 : * ensure that these options are not overwritten by the user.
2521 : */
2522 : static bool
2523 16 : pgfdw_has_required_scram_options(const char **keywords, const char **values)
2524 : {
2525 16 : bool has_scram_server_key = false;
2526 16 : bool has_scram_client_key = false;
2527 16 : bool has_require_auth = false;
2528 16 : bool has_scram_keys = false;
2529 :
2530 : /*
2531 : * Continue iterating even if we found the keys that we need to validate
2532 : * to make sure that there is no other declaration of these keys that can
2533 : * overwrite the first.
2534 : */
2535 160 : for (int i = 0; keywords[i] != NULL; i++)
2536 : {
2537 144 : if (strcmp(keywords[i], "scram_client_key") == 0)
2538 : {
2539 16 : if (values[i] != NULL && values[i][0] != '\0')
2540 16 : has_scram_client_key = true;
2541 : else
2542 0 : has_scram_client_key = false;
2543 : }
2544 :
2545 144 : if (strcmp(keywords[i], "scram_server_key") == 0)
2546 : {
2547 16 : if (values[i] != NULL && values[i][0] != '\0')
2548 16 : has_scram_server_key = true;
2549 : else
2550 0 : has_scram_server_key = false;
2551 : }
2552 :
2553 144 : if (strcmp(keywords[i], "require_auth") == 0)
2554 : {
2555 16 : if (values[i] != NULL && strcmp(values[i], "scram-sha-256") == 0)
2556 16 : has_require_auth = true;
2557 : else
2558 0 : has_require_auth = false;
2559 : }
2560 : }
2561 :
2562 16 : has_scram_keys = has_scram_client_key && has_scram_server_key && MyProcPort->has_scram_keys;
2563 :
2564 16 : return (has_scram_keys && has_require_auth);
2565 : }
|
