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1 : : /*-------------------------------------------------------------------------
2 : : *
3 : : * connection.c
4 : : * Connection management functions for postgres_fdw
5 : : *
6 : : * Portions Copyright (c) 2012-2026, PostgreSQL Global Development Group
7 : : *
8 : : * IDENTIFICATION
9 : : * contrib/postgres_fdw/connection.c
10 : : *
11 : : *-------------------------------------------------------------------------
12 : : */
13 : : #include "postgres.h"
14 : :
15 : : #if HAVE_POLL_H
16 : : #include <poll.h>
17 : : #endif
18 : :
19 : : #include "access/htup_details.h"
20 : : #include "access/xact.h"
21 : : #include "catalog/pg_user_mapping.h"
22 : : #include "commands/defrem.h"
23 : : #include "common/base64.h"
24 : : #include "funcapi.h"
25 : : #include "libpq/libpq-be.h"
26 : : #include "libpq/libpq-be-fe-helpers.h"
27 : : #include "mb/pg_wchar.h"
28 : : #include "miscadmin.h"
29 : : #include "pgstat.h"
30 : : #include "postgres_fdw.h"
31 : : #include "storage/latch.h"
32 : : #include "utils/builtins.h"
33 : : #include "utils/hsearch.h"
34 : : #include "utils/inval.h"
35 : : #include "utils/syscache.h"
36 : : #include "utils/tuplestore.h"
37 : :
38 : : /*
39 : : * Connection cache hash table entry
40 : : *
41 : : * The lookup key in this hash table is the user mapping OID. We use just one
42 : : * connection per user mapping ID, which ensures that all the scans use the
43 : : * same snapshot during a query. Using the user mapping OID rather than
44 : : * the foreign server OID + user OID avoids creating multiple connections when
45 : : * the public user mapping applies to all user OIDs.
46 : : *
47 : : * The "conn" pointer can be NULL if we don't currently have a live connection.
48 : : * When we do have a connection, xact_depth tracks the current depth of
49 : : * transactions and subtransactions open on the remote side. We need to issue
50 : : * commands at the same nesting depth on the remote as we're executing at
51 : : * ourselves, so that rolling back a subtransaction will kill the right
52 : : * queries and not the wrong ones.
53 : : */
54 : : typedef Oid ConnCacheKey;
55 : :
56 : : typedef struct ConnCacheEntry
57 : : {
58 : : ConnCacheKey key; /* hash key (must be first) */
59 : : PGconn *conn; /* connection to foreign server, or NULL */
60 : : /* Remaining fields are invalid when conn is NULL: */
61 : : int xact_depth; /* 0 = no xact open, 1 = main xact open, 2 =
62 : : * one level of subxact open, etc */
63 : : bool xact_read_only; /* xact r/o state */
64 : : bool have_prep_stmt; /* have we prepared any stmts in this xact? */
65 : : bool have_error; /* have any subxacts aborted in this xact? */
66 : : bool changing_xact_state; /* xact state change in process */
67 : : bool parallel_commit; /* do we commit (sub)xacts in parallel? */
68 : : bool parallel_abort; /* do we abort (sub)xacts in parallel? */
69 : : bool invalidated; /* true if reconnect is pending */
70 : : bool keep_connections; /* setting value of keep_connections
71 : : * server option */
72 : : Oid serverid; /* foreign server OID used to get server name */
73 : : uint32 server_hashvalue; /* hash value of foreign server OID */
74 : : uint32 mapping_hashvalue; /* hash value of user mapping OID */
75 : : PgFdwConnState state; /* extra per-connection state */
76 : : } ConnCacheEntry;
77 : :
78 : : /*
79 : : * Connection cache (initialized on first use)
80 : : */
81 : : static HTAB *ConnectionHash = NULL;
82 : :
83 : : /* for assigning cursor numbers and prepared statement numbers */
84 : : static unsigned int cursor_number = 0;
85 : : static unsigned int prep_stmt_number = 0;
86 : :
87 : : /* tracks whether any work is needed in callback functions */
88 : : static bool xact_got_connection = false;
89 : :
90 : : /*
91 : : * tracks the topmost read-only local transaction's nesting level determined
92 : : * by GetTopReadOnlyTransactionNestLevel()
93 : : */
94 : : static int read_only_level = 0;
95 : :
96 : : /* custom wait event values, retrieved from shared memory */
97 : : static uint32 pgfdw_we_cleanup_result = 0;
98 : : static uint32 pgfdw_we_connect = 0;
99 : : static uint32 pgfdw_we_get_result = 0;
100 : :
101 : : /*
102 : : * Milliseconds to wait to cancel an in-progress query or execute a cleanup
103 : : * query; if it takes longer than 30 seconds to do these, we assume the
104 : : * connection is dead.
105 : : */
106 : : #define CONNECTION_CLEANUP_TIMEOUT 30000
107 : :
108 : : /*
109 : : * Milliseconds to wait before issuing another cancel request. This covers
110 : : * the race condition where the remote session ignored our cancel request
111 : : * because it arrived while idle.
112 : : */
113 : : #define RETRY_CANCEL_TIMEOUT 1000
114 : :
115 : : /* Macro for constructing abort command to be sent */
116 : : #define CONSTRUCT_ABORT_COMMAND(sql, entry, toplevel) \
117 : : do { \
118 : : if (toplevel) \
119 : : snprintf((sql), sizeof(sql), \
120 : : "ABORT TRANSACTION"); \
121 : : else \
122 : : snprintf((sql), sizeof(sql), \
123 : : "ROLLBACK TO SAVEPOINT s%d; RELEASE SAVEPOINT s%d", \
124 : : (entry)->xact_depth, (entry)->xact_depth); \
125 : : } while(0)
126 : :
127 : : /*
128 : : * Extension version number, for supporting older extension versions' objects
129 : : */
130 : : enum pgfdwVersion
131 : : {
132 : : PGFDW_V1_1 = 0,
133 : : PGFDW_V1_2,
134 : : };
135 : :
136 : : /*
137 : : * SQL functions
138 : : */
139 : 6 : PG_FUNCTION_INFO_V1(postgres_fdw_get_connections);
140 : 7 : PG_FUNCTION_INFO_V1(postgres_fdw_get_connections_1_2);
141 : 7 : PG_FUNCTION_INFO_V1(postgres_fdw_disconnect);
142 : 7 : PG_FUNCTION_INFO_V1(postgres_fdw_disconnect_all);
143 : 16 : PG_FUNCTION_INFO_V1(postgres_fdw_connection);
144 : :
145 : : /* prototypes of private functions */
146 : : static void make_new_connection(ConnCacheEntry *entry, UserMapping *user);
147 : : static PGconn *connect_pg_server(ForeignServer *server, UserMapping *user);
148 : : static void disconnect_pg_server(ConnCacheEntry *entry);
149 : : static void check_conn_params(const char **keywords, const char **values, UserMapping *user);
150 : : static void configure_remote_session(PGconn *conn);
151 : : static void do_sql_command_begin(PGconn *conn, const char *sql);
152 : : static void do_sql_command_end(PGconn *conn, const char *sql,
153 : : bool consume_input);
154 : : static void begin_remote_xact(ConnCacheEntry *entry);
155 : : static void pgfdw_report_internal(int elevel, PGresult *res, PGconn *conn,
156 : : const char *sql);
157 : : static void pgfdw_xact_callback(XactEvent event, void *arg);
158 : : static void pgfdw_subxact_callback(SubXactEvent event,
159 : : SubTransactionId mySubid,
160 : : SubTransactionId parentSubid,
161 : : void *arg);
162 : : static void pgfdw_inval_callback(Datum arg, SysCacheIdentifier cacheid,
163 : : uint32 hashvalue);
164 : : static void pgfdw_reject_incomplete_xact_state_change(ConnCacheEntry *entry);
165 : : static void pgfdw_reset_xact_state(ConnCacheEntry *entry, bool toplevel);
166 : : static bool pgfdw_cancel_query(PGconn *conn);
167 : : static bool pgfdw_cancel_query_begin(PGconn *conn, TimestampTz endtime);
168 : : static bool pgfdw_cancel_query_end(PGconn *conn, TimestampTz endtime,
169 : : TimestampTz retrycanceltime,
170 : : bool consume_input);
171 : : static bool pgfdw_exec_cleanup_query(PGconn *conn, const char *query,
172 : : bool ignore_errors);
173 : : static bool pgfdw_exec_cleanup_query_begin(PGconn *conn, const char *query);
174 : : static bool pgfdw_exec_cleanup_query_end(PGconn *conn, const char *query,
175 : : TimestampTz endtime,
176 : : bool consume_input,
177 : : bool ignore_errors);
178 : : static bool pgfdw_get_cleanup_result(PGconn *conn, TimestampTz endtime,
179 : : TimestampTz retrycanceltime,
180 : : PGresult **result, bool *timed_out);
181 : : static void pgfdw_abort_cleanup(ConnCacheEntry *entry, bool toplevel);
182 : : static bool pgfdw_abort_cleanup_begin(ConnCacheEntry *entry, bool toplevel,
183 : : List **pending_entries,
184 : : List **cancel_requested);
185 : : static void pgfdw_finish_pre_commit_cleanup(List *pending_entries);
186 : : static void pgfdw_finish_pre_subcommit_cleanup(List *pending_entries,
187 : : int curlevel);
188 : : static void pgfdw_finish_abort_cleanup(List *pending_entries,
189 : : List *cancel_requested,
190 : : bool toplevel);
191 : : static void pgfdw_security_check(const char **keywords, const char **values,
192 : : UserMapping *user, PGconn *conn);
193 : : static bool UserMappingPasswordRequired(UserMapping *user);
194 : : static bool UseScramPassthrough(ForeignServer *server, UserMapping *user);
195 : : static bool disconnect_cached_connections(Oid serverid);
196 : : static void postgres_fdw_get_connections_internal(FunctionCallInfo fcinfo,
197 : : enum pgfdwVersion api_version);
198 : : static int pgfdw_conn_check(PGconn *conn);
199 : : static bool pgfdw_conn_checkable(void);
200 : : static bool pgfdw_has_required_scram_options(const char **keywords, const char **values);
201 : :
202 : : /*
203 : : * Get a PGconn which can be used to execute queries on the remote PostgreSQL
204 : : * server with the user's authorization. A new connection is established
205 : : * if we don't already have a suitable one, and a transaction is opened at
206 : : * the right subtransaction nesting depth if we didn't do that already.
207 : : *
208 : : * will_prep_stmt must be true if caller intends to create any prepared
209 : : * statements. Since those don't go away automatically at transaction end
210 : : * (not even on error), we need this flag to cue manual cleanup.
211 : : *
212 : : * If state is not NULL, *state receives the per-connection state associated
213 : : * with the PGconn.
214 : : */
215 : : PGconn *
216 : 2297 : GetConnection(UserMapping *user, bool will_prep_stmt, PgFdwConnState **state)
217 : : {
218 : : bool found;
219 : 2297 : bool retry = false;
220 : : ConnCacheEntry *entry;
221 : : ConnCacheKey key;
222 : 2297 : MemoryContext ccxt = CurrentMemoryContext;
223 : :
224 : : /* First time through, initialize connection cache hashtable */
225 [ + + ]: 2297 : if (ConnectionHash == NULL)
226 : : {
227 : : HASHCTL ctl;
228 : :
229 [ + - ]: 11 : if (pgfdw_we_get_result == 0)
230 : 11 : pgfdw_we_get_result =
231 : 11 : WaitEventExtensionNew("PostgresFdwGetResult");
232 : :
233 : 11 : ctl.keysize = sizeof(ConnCacheKey);
234 : 11 : ctl.entrysize = sizeof(ConnCacheEntry);
235 : 11 : ConnectionHash = hash_create("postgres_fdw connections", 8,
236 : : &ctl,
237 : : HASH_ELEM | HASH_BLOBS);
238 : :
239 : : /*
240 : : * Register some callback functions that manage connection cleanup.
241 : : * This should be done just once in each backend.
242 : : */
243 : 11 : RegisterXactCallback(pgfdw_xact_callback, NULL);
244 : 11 : RegisterSubXactCallback(pgfdw_subxact_callback, NULL);
245 : 11 : CacheRegisterSyscacheCallback(FOREIGNSERVEROID,
246 : : pgfdw_inval_callback, (Datum) 0);
247 : 11 : CacheRegisterSyscacheCallback(USERMAPPINGOID,
248 : : pgfdw_inval_callback, (Datum) 0);
249 : : }
250 : :
251 : : /* Set flag that we did GetConnection during the current transaction */
252 : 2297 : xact_got_connection = true;
253 : :
254 : : /* Create hash key for the entry. Assume no pad bytes in key struct */
255 : 2297 : key = user->umid;
256 : :
257 : : /*
258 : : * Find or create cached entry for requested connection.
259 : : */
260 : 2297 : entry = hash_search(ConnectionHash, &key, HASH_ENTER, &found);
261 [ + + ]: 2297 : if (!found)
262 : : {
263 : : /*
264 : : * We need only clear "conn" here; remaining fields will be filled
265 : : * later when "conn" is set.
266 : : */
267 : 22 : entry->conn = NULL;
268 : : }
269 : :
270 : : /* Reject further use of connections which failed abort cleanup. */
271 : 2297 : pgfdw_reject_incomplete_xact_state_change(entry);
272 : :
273 : : /*
274 : : * If the connection needs to be remade due to invalidation, disconnect as
275 : : * soon as we're out of all transactions.
276 : : */
277 [ + + - + : 2295 : if (entry->conn != NULL && entry->invalidated && entry->xact_depth == 0)
- - ]
278 : : {
279 [ # # ]: 0 : elog(DEBUG3, "closing connection %p for option changes to take effect",
280 : : entry->conn);
281 : 0 : disconnect_pg_server(entry);
282 : : }
283 : :
284 : : /*
285 : : * If cache entry doesn't have a connection, we have to establish a new
286 : : * connection. (If connect_pg_server throws an error, the cache entry
287 : : * will remain in a valid empty state, ie conn == NULL.)
288 : : */
289 [ + + ]: 2295 : if (entry->conn == NULL)
290 : 86 : make_new_connection(entry, user);
291 : :
292 : : /*
293 : : * We check the health of the cached connection here when using it. In
294 : : * cases where we're out of all transactions, if a broken connection is
295 : : * detected, we try to reestablish a new connection later.
296 : : */
297 [ + + ]: 2288 : PG_TRY();
298 : : {
299 : : /* Process a pending asynchronous request if any. */
300 [ - + ]: 2288 : if (entry->state.pendingAreq)
301 : 0 : process_pending_request(entry->state.pendingAreq);
302 : : /* Start a new transaction or subtransaction if needed. */
303 : 2288 : begin_remote_xact(entry);
304 : : }
305 : 2 : PG_CATCH();
306 : : {
307 : 2 : MemoryContext ecxt = MemoryContextSwitchTo(ccxt);
308 : 2 : ErrorData *errdata = CopyErrorData();
309 : :
310 : : /*
311 : : * Determine whether to try to reestablish the connection.
312 : : *
313 : : * After a broken connection is detected in libpq, any error other
314 : : * than connection failure (e.g., out-of-memory) can be thrown
315 : : * somewhere between return from libpq and the expected ereport() call
316 : : * in pgfdw_report_error(). In this case, since PQstatus() indicates
317 : : * CONNECTION_BAD, checking only PQstatus() causes the false detection
318 : : * of connection failure. To avoid this, we also verify that the
319 : : * error's sqlstate is ERRCODE_CONNECTION_FAILURE. Note that also
320 : : * checking only the sqlstate can cause another false detection
321 : : * because pgfdw_report_error() may report ERRCODE_CONNECTION_FAILURE
322 : : * for any libpq-originated error condition.
323 : : */
324 [ + - ]: 2 : if (errdata->sqlerrcode != ERRCODE_CONNECTION_FAILURE ||
325 [ + - ]: 2 : PQstatus(entry->conn) != CONNECTION_BAD ||
326 [ + + ]: 2 : entry->xact_depth > 0)
327 : : {
328 : 1 : MemoryContextSwitchTo(ecxt);
329 : 1 : PG_RE_THROW();
330 : : }
331 : :
332 : : /* Clean up the error state */
333 : 1 : FlushErrorState();
334 : 1 : FreeErrorData(errdata);
335 : 1 : errdata = NULL;
336 : :
337 : 1 : retry = true;
338 : : }
339 [ - + ]: 2287 : PG_END_TRY();
340 : :
341 : : /*
342 : : * If a broken connection is detected, disconnect it, reestablish a new
343 : : * connection and retry a new remote transaction. If connection failure is
344 : : * reported again, we give up getting a connection.
345 : : */
346 [ + + ]: 2287 : if (retry)
347 : : {
348 : : Assert(entry->xact_depth == 0);
349 : :
350 [ - + ]: 1 : ereport(DEBUG3,
351 : : (errmsg_internal("could not start remote transaction on connection %p",
352 : : entry->conn)),
353 : : errdetail_internal("%s", pchomp(PQerrorMessage(entry->conn))));
354 : :
355 [ - + ]: 1 : elog(DEBUG3, "closing connection %p to reestablish a new one",
356 : : entry->conn);
357 : 1 : disconnect_pg_server(entry);
358 : :
359 : 1 : make_new_connection(entry, user);
360 : :
361 : 1 : begin_remote_xact(entry);
362 : : }
363 : :
364 : : /* Remember if caller will prepare statements */
365 : 2287 : entry->have_prep_stmt |= will_prep_stmt;
366 : :
367 : : /* If caller needs access to the per-connection state, return it. */
368 [ + + ]: 2287 : if (state)
369 : 785 : *state = &entry->state;
370 : :
371 : 2287 : return entry->conn;
372 : : }
373 : :
374 : : /*
375 : : * Reset all transient state fields in the cached connection entry and
376 : : * establish new connection to the remote server.
377 : : */
378 : : static void
379 : 87 : make_new_connection(ConnCacheEntry *entry, UserMapping *user)
380 : : {
381 : 87 : ForeignServer *server = GetForeignServer(user->serverid);
382 : : ListCell *lc;
383 : :
384 : : Assert(entry->conn == NULL);
385 : :
386 : : /* Reset all transient state fields, to be sure all are clean */
387 : 87 : entry->xact_depth = 0;
388 : 87 : entry->xact_read_only = false;
389 : 87 : entry->have_prep_stmt = false;
390 : 87 : entry->have_error = false;
391 : 87 : entry->changing_xact_state = false;
392 : 87 : entry->invalidated = false;
393 : 87 : entry->serverid = server->serverid;
394 : 87 : entry->server_hashvalue =
395 : 87 : GetSysCacheHashValue1(FOREIGNSERVEROID,
396 : : ObjectIdGetDatum(server->serverid));
397 : 87 : entry->mapping_hashvalue =
398 : 87 : GetSysCacheHashValue1(USERMAPPINGOID,
399 : : ObjectIdGetDatum(user->umid));
400 : 87 : memset(&entry->state, 0, sizeof(entry->state));
401 : :
402 : : /*
403 : : * Determine whether to keep the connection that we're about to make here
404 : : * open even after the transaction using it ends, so that the subsequent
405 : : * transactions can re-use it.
406 : : *
407 : : * By default, all the connections to any foreign servers are kept open.
408 : : *
409 : : * Also determine whether to commit/abort (sub)transactions opened on the
410 : : * remote server in parallel at (sub)transaction end, which is disabled by
411 : : * default.
412 : : *
413 : : * Note: it's enough to determine these only when making a new connection
414 : : * because if these settings for it are changed, it will be closed and
415 : : * re-made later.
416 : : */
417 : 87 : entry->keep_connections = true;
418 : 87 : entry->parallel_commit = false;
419 : 87 : entry->parallel_abort = false;
420 [ + - + + : 407 : foreach(lc, server->options)
+ + ]
421 : : {
422 : 320 : DefElem *def = (DefElem *) lfirst(lc);
423 : :
424 [ + + ]: 320 : if (strcmp(def->defname, "keep_connections") == 0)
425 : 17 : entry->keep_connections = defGetBoolean(def);
426 [ + + ]: 303 : else if (strcmp(def->defname, "parallel_commit") == 0)
427 : 2 : entry->parallel_commit = defGetBoolean(def);
428 [ + + ]: 301 : else if (strcmp(def->defname, "parallel_abort") == 0)
429 : 2 : entry->parallel_abort = defGetBoolean(def);
430 : : }
431 : :
432 : : /* Now try to make the connection */
433 : 87 : entry->conn = connect_pg_server(server, user);
434 : :
435 [ - + ]: 80 : elog(DEBUG3, "new postgres_fdw connection %p for server \"%s\" (user mapping oid %u, userid %u)",
436 : : entry->conn, server->servername, user->umid, user->userid);
437 : 80 : }
438 : :
439 : : /*
440 : : * Check that non-superuser has used password or delegated credentials
441 : : * to establish connection; otherwise, he's piggybacking on the
442 : : * postgres server's user identity. See also dblink_security_check()
443 : : * in contrib/dblink and check_conn_params.
444 : : */
445 : : static void
446 : 82 : pgfdw_security_check(const char **keywords, const char **values, UserMapping *user, PGconn *conn)
447 : : {
448 : : /* Superusers bypass the check */
449 [ + + ]: 82 : if (superuser_arg(user->userid))
450 : 74 : return;
451 : :
452 : : #ifdef ENABLE_GSS
453 : : /* Connected via GSSAPI with delegated credentials- all good. */
454 : : if (PQconnectionUsedGSSAPI(conn) && be_gssapi_get_delegation(MyProcPort))
455 : : return;
456 : : #endif
457 : :
458 : : /* Ok if superuser set PW required false. */
459 [ + + ]: 8 : if (!UserMappingPasswordRequired(user))
460 : 2 : return;
461 : :
462 : : /* Connected via PW, with PW required true, and provided non-empty PW. */
463 [ + + ]: 6 : if (PQconnectionUsedPassword(conn))
464 : : {
465 : : /* ok if params contain a non-empty password */
466 [ + + ]: 40 : for (int i = 0; keywords[i] != NULL; i++)
467 : : {
468 [ - + - - ]: 36 : if (strcmp(keywords[i], "password") == 0 && values[i][0] != '\0')
469 : 0 : return;
470 : : }
471 : : }
472 : :
473 : : /*
474 : : * Ok if SCRAM pass-through is being used and all required SCRAM options
475 : : * are set correctly. If pgfdw_has_required_scram_options returns true we
476 : : * assume that UseScramPassthrough is also true since SCRAM options are
477 : : * only set when UseScramPassthrough is enabled.
478 : : */
479 [ + - + + : 6 : if (MyProcPort != NULL && MyProcPort->has_scram_keys && pgfdw_has_required_scram_options(keywords, values))
+ - ]
480 : 4 : return;
481 : :
482 [ + - ]: 2 : ereport(ERROR,
483 : : (errcode(ERRCODE_S_R_E_PROHIBITED_SQL_STATEMENT_ATTEMPTED),
484 : : errmsg("password or GSSAPI delegated credentials required"),
485 : : errdetail("Non-superuser cannot connect if the server does not request a password or use GSSAPI with delegated credentials."),
486 : : errhint("Target server's authentication method must be changed or password_required=false set in the user mapping attributes.")));
487 : : }
488 : :
489 : : /*
490 : : * Construct connection params from generic options of ForeignServer and
491 : : * UserMapping. (Some of them might not be libpq options, in which case we'll
492 : : * just waste a few array slots.)
493 : : */
494 : : static void
495 : 98 : construct_connection_params(ForeignServer *server, UserMapping *user,
496 : : const char ***p_keywords, const char ***p_values,
497 : : char **p_appname)
498 : : {
499 : : const char **keywords;
500 : : const char **values;
501 : 98 : char *appname = NULL;
502 : : int n;
503 : :
504 : : /*
505 : : * Add 4 extra slots for application_name, fallback_application_name,
506 : : * client_encoding, end marker, and 3 extra slots for scram keys and
507 : : * required scram pass-through options.
508 : : */
509 : 98 : n = list_length(server->options) + list_length(user->options) + 4 + 3;
510 : 98 : keywords = (const char **) palloc(n * sizeof(char *));
511 : 98 : values = (const char **) palloc(n * sizeof(char *));
512 : :
513 : 98 : n = 0;
514 : 196 : n += ExtractConnectionOptions(server->options,
515 : 98 : keywords + n, values + n);
516 : 196 : n += ExtractConnectionOptions(user->options,
517 : 98 : keywords + n, values + n);
518 : :
519 : : /*
520 : : * Use pgfdw_application_name as application_name if set.
521 : : *
522 : : * PQconnectdbParams() processes the parameter arrays from start to end.
523 : : * If any key word is repeated, the last value is used. Therefore note
524 : : * that pgfdw_application_name must be added to the arrays after options
525 : : * of ForeignServer are, so that it can override application_name set in
526 : : * ForeignServer.
527 : : */
528 [ + + + - ]: 98 : if (pgfdw_application_name && *pgfdw_application_name != '\0')
529 : : {
530 : 1 : keywords[n] = "application_name";
531 : 1 : values[n] = pgfdw_application_name;
532 : 1 : n++;
533 : : }
534 : :
535 : : /*
536 : : * Search the parameter arrays to find application_name setting, and
537 : : * replace escape sequences in it with status information if found. The
538 : : * arrays are searched backwards because the last value is used if
539 : : * application_name is repeatedly set.
540 : : */
541 [ + + ]: 282 : for (int i = n - 1; i >= 0; i--)
542 : : {
543 [ + + ]: 212 : if (strcmp(keywords[i], "application_name") == 0 &&
544 [ + - ]: 28 : *(values[i]) != '\0')
545 : : {
546 : : /*
547 : : * Use this application_name setting if it's not empty string even
548 : : * after any escape sequences in it are replaced.
549 : : */
550 : 28 : appname = process_pgfdw_appname(values[i]);
551 [ + - ]: 28 : if (appname[0] != '\0')
552 : : {
553 : 28 : values[i] = appname;
554 : 28 : break;
555 : : }
556 : :
557 : : /*
558 : : * This empty application_name is not used, so we set values[i] to
559 : : * NULL and keep searching the array to find the next one.
560 : : */
561 : 0 : values[i] = NULL;
562 : 0 : pfree(appname);
563 : 0 : appname = NULL;
564 : : }
565 : : }
566 : :
567 : 98 : *p_appname = appname;
568 : :
569 : : /* Use "postgres_fdw" as fallback_application_name */
570 : 98 : keywords[n] = "fallback_application_name";
571 : 98 : values[n] = "postgres_fdw";
572 : 98 : n++;
573 : :
574 : : /* Set client_encoding so that libpq can convert encoding properly. */
575 : 98 : keywords[n] = "client_encoding";
576 : 98 : values[n] = GetDatabaseEncodingName();
577 : 98 : n++;
578 : :
579 : : /* Add required SCRAM pass-through connection options if it's enabled. */
580 [ + + + + : 98 : if (MyProcPort != NULL && MyProcPort->has_scram_keys && UseScramPassthrough(server, user))
+ + ]
581 : : {
582 : : int len;
583 : : int encoded_len;
584 : :
585 : 4 : keywords[n] = "scram_client_key";
586 : 4 : len = pg_b64_enc_len(sizeof(MyProcPort->scram_ClientKey));
587 : : /* don't forget the zero-terminator */
588 : 4 : values[n] = palloc0(len + 1);
589 : 4 : encoded_len = pg_b64_encode(MyProcPort->scram_ClientKey,
590 : : sizeof(MyProcPort->scram_ClientKey),
591 : 4 : (char *) values[n], len);
592 [ - + ]: 4 : if (encoded_len < 0)
593 [ # # ]: 0 : elog(ERROR, "could not encode SCRAM client key");
594 : 4 : n++;
595 : :
596 : 4 : keywords[n] = "scram_server_key";
597 : 4 : len = pg_b64_enc_len(sizeof(MyProcPort->scram_ServerKey));
598 : : /* don't forget the zero-terminator */
599 : 4 : values[n] = palloc0(len + 1);
600 : 4 : encoded_len = pg_b64_encode(MyProcPort->scram_ServerKey,
601 : : sizeof(MyProcPort->scram_ServerKey),
602 : 4 : (char *) values[n], len);
603 [ - + ]: 4 : if (encoded_len < 0)
604 [ # # ]: 0 : elog(ERROR, "could not encode SCRAM server key");
605 : 4 : n++;
606 : :
607 : : /*
608 : : * Require scram-sha-256 to ensure that no other auth method is used
609 : : * when connecting with foreign server.
610 : : */
611 : 4 : keywords[n] = "require_auth";
612 : 4 : values[n] = "scram-sha-256";
613 : 4 : n++;
614 : : }
615 : :
616 : 98 : keywords[n] = values[n] = NULL;
617 : :
618 : : /* Verify the set of connection parameters. */
619 : 98 : check_conn_params(keywords, values, user);
620 : :
621 : 95 : *p_keywords = keywords;
622 : 95 : *p_values = values;
623 : 95 : }
624 : :
625 : : /*
626 : : * Connect to remote server using specified server and user mapping properties.
627 : : */
628 : : static PGconn *
629 : 87 : connect_pg_server(ForeignServer *server, UserMapping *user)
630 : : {
631 : 87 : PGconn *volatile conn = NULL;
632 : :
633 : : /*
634 : : * Use PG_TRY block to ensure closing connection on error.
635 : : */
636 [ + + ]: 87 : PG_TRY();
637 : : {
638 : : const char **keywords;
639 : : const char **values;
640 : : char *appname;
641 : : PGconn *start_conn;
642 : :
643 : 87 : construct_connection_params(server, user, &keywords, &values, &appname);
644 : :
645 : : /* first time, allocate or get the custom wait event */
646 [ + + ]: 84 : if (pgfdw_we_connect == 0)
647 : 10 : pgfdw_we_connect = WaitEventExtensionNew("PostgresFdwConnect");
648 : :
649 : : /* OK to make connection */
650 : : start_conn =
651 : 84 : libpqsrv_connect_params_start(keywords, values,
652 : : /* expand_dbname = */ false);
653 : 84 : PQsetNoticeReceiver(start_conn, libpqsrv_notice_receiver,
654 : : "received message via remote connection");
655 : 84 : libpqsrv_connect_complete(start_conn, pgfdw_we_connect);
656 : 84 : conn = start_conn;
657 : :
658 [ + - + + ]: 84 : if (!conn || PQstatus(conn) != CONNECTION_OK)
659 [ + - ]: 2 : ereport(ERROR,
660 : : (errcode(ERRCODE_SQLCLIENT_UNABLE_TO_ESTABLISH_SQLCONNECTION),
661 : : errmsg("could not connect to server \"%s\"",
662 : : server->servername),
663 : : errdetail_internal("%s", pchomp(PQerrorMessage(conn)))));
664 : :
665 : : /* Perform post-connection security checks. */
666 : 82 : pgfdw_security_check(keywords, values, user, conn);
667 : :
668 : : /* Prepare new session for use */
669 : 80 : configure_remote_session(conn);
670 : :
671 [ + + ]: 80 : if (appname != NULL)
672 : 27 : pfree(appname);
673 : 80 : pfree(keywords);
674 : 80 : pfree(values);
675 : : }
676 : 7 : PG_CATCH();
677 : : {
678 : 7 : libpqsrv_disconnect(conn);
679 : 7 : PG_RE_THROW();
680 : : }
681 [ - + ]: 80 : PG_END_TRY();
682 : :
683 : 80 : return conn;
684 : : }
685 : :
686 : : /*
687 : : * Disconnect any open connection for a connection cache entry.
688 : : */
689 : : static void
690 : 71 : disconnect_pg_server(ConnCacheEntry *entry)
691 : : {
692 [ + - ]: 71 : if (entry->conn != NULL)
693 : : {
694 : 71 : libpqsrv_disconnect(entry->conn);
695 : 71 : entry->conn = NULL;
696 : : }
697 : 71 : }
698 : :
699 : : /*
700 : : * Check and return the value of password_required, if defined; otherwise,
701 : : * return true, which is the default value of it. The mapping has been
702 : : * pre-validated.
703 : : */
704 : : static bool
705 : 16 : UserMappingPasswordRequired(UserMapping *user)
706 : : {
707 : : ListCell *cell;
708 : :
709 [ + + + + : 29 : foreach(cell, user->options)
+ + ]
710 : : {
711 : 16 : DefElem *def = (DefElem *) lfirst(cell);
712 : :
713 [ + + ]: 16 : if (strcmp(def->defname, "password_required") == 0)
714 : 3 : return defGetBoolean(def);
715 : : }
716 : :
717 : 13 : return true;
718 : : }
719 : :
720 : : /*
721 : : * Return whether SCRAM pass-through is enabled.
722 : : *
723 : : * If use_scram_passthrough is specified in both the foreign server
724 : : * and the user mapping, the user mapping setting takes precedence.
725 : : */
726 : : static bool
727 : 5 : UseScramPassthrough(ForeignServer *server, UserMapping *user)
728 : : {
729 : : ListCell *cell;
730 : :
731 [ + - + + : 10 : foreach(cell, user->options)
+ + ]
732 : : {
733 : 6 : DefElem *def = (DefElem *) lfirst(cell);
734 : :
735 [ + + ]: 6 : if (strcmp(def->defname, "use_scram_passthrough") == 0)
736 : 1 : return defGetBoolean(def);
737 : : }
738 : :
739 [ + - + - : 16 : foreach(cell, server->options)
+ - ]
740 : : {
741 : 16 : DefElem *def = (DefElem *) lfirst(cell);
742 : :
743 [ + + ]: 16 : if (strcmp(def->defname, "use_scram_passthrough") == 0)
744 : 4 : return defGetBoolean(def);
745 : : }
746 : :
747 : 0 : return false;
748 : : }
749 : :
750 : : /*
751 : : * For non-superusers, insist that the connstr specify a password or that the
752 : : * user provided their own GSSAPI delegated credentials. This
753 : : * prevents a password from being picked up from .pgpass, a service file, the
754 : : * environment, etc. We don't want the postgres user's passwords,
755 : : * certificates, etc to be accessible to non-superusers. (See also
756 : : * dblink_connstr_check in contrib/dblink.)
757 : : */
758 : : static void
759 : 98 : check_conn_params(const char **keywords, const char **values, UserMapping *user)
760 : : {
761 : : int i;
762 : :
763 : : /* no check required if superuser */
764 [ + + ]: 98 : if (superuser_arg(user->userid))
765 : 85 : return;
766 : :
767 : : #ifdef ENABLE_GSS
768 : : /* ok if the user provided their own delegated credentials */
769 : : if (be_gssapi_get_delegation(MyProcPort))
770 : : return;
771 : : #endif
772 : :
773 : : /* ok if params contain a non-empty password */
774 [ + + ]: 81 : for (i = 0; keywords[i] != NULL; i++)
775 : : {
776 [ + + + - ]: 73 : if (strcmp(keywords[i], "password") == 0 && values[i][0] != '\0')
777 : 5 : return;
778 : : }
779 : :
780 : : /* ok if the superuser explicitly said so at user mapping creation time */
781 [ + + ]: 8 : if (!UserMappingPasswordRequired(user))
782 : 1 : return;
783 : :
784 : : /*
785 : : * Ok if SCRAM pass-through is being used and all required scram options
786 : : * are set correctly. If pgfdw_has_required_scram_options returns true we
787 : : * assume that UseScramPassthrough is also true since SCRAM options are
788 : : * only set when UseScramPassthrough is enabled.
789 : : */
790 [ + - + + : 7 : if (MyProcPort != NULL && MyProcPort->has_scram_keys && pgfdw_has_required_scram_options(keywords, values))
+ + ]
791 : 4 : return;
792 : :
793 [ + - ]: 3 : ereport(ERROR,
794 : : (errcode(ERRCODE_S_R_E_PROHIBITED_SQL_STATEMENT_ATTEMPTED),
795 : : errmsg("password or GSSAPI delegated credentials required"),
796 : : errdetail("Non-superusers must delegate GSSAPI credentials, provide a password, or enable SCRAM pass-through in user mapping.")));
797 : : }
798 : :
799 : : /*
800 : : * Issue SET commands to make sure remote session is configured properly.
801 : : *
802 : : * We do this just once at connection, assuming nothing will change the
803 : : * values later. Since we'll never send volatile function calls to the
804 : : * remote, there shouldn't be any way to break this assumption from our end.
805 : : * It's possible to think of ways to break it at the remote end, eg making
806 : : * a foreign table point to a view that includes a set_config call ---
807 : : * but once you admit the possibility of a malicious view definition,
808 : : * there are any number of ways to break things.
809 : : */
810 : : static void
811 : 80 : configure_remote_session(PGconn *conn)
812 : : {
813 : 80 : int remoteversion = PQserverVersion(conn);
814 : :
815 : : /* Force the search path to contain only pg_catalog (see deparse.c) */
816 : 80 : do_sql_command(conn, "SET search_path = pg_catalog");
817 : :
818 : : /*
819 : : * Set remote timezone; this is basically just cosmetic, since all
820 : : * transmitted and returned timestamptzs should specify a zone explicitly
821 : : * anyway. However it makes the regression test outputs more predictable.
822 : : *
823 : : * We don't risk setting remote zone equal to ours, since the remote
824 : : * server might use a different timezone database. Instead, use GMT
825 : : * (quoted, because very old servers are picky about case). That's
826 : : * guaranteed to work regardless of the remote's timezone database,
827 : : * because pg_tzset() hard-wires it (at least in PG 9.2 and later).
828 : : */
829 : 80 : do_sql_command(conn, "SET timezone = 'GMT'");
830 : :
831 : : /*
832 : : * Set values needed to ensure unambiguous data output from remote. (This
833 : : * logic should match what pg_dump does. See also set_transmission_modes
834 : : * in postgres_fdw.c.)
835 : : */
836 : 80 : do_sql_command(conn, "SET datestyle = ISO");
837 [ + - ]: 80 : if (remoteversion >= 80400)
838 : 80 : do_sql_command(conn, "SET intervalstyle = postgres");
839 [ + - ]: 80 : if (remoteversion >= 90000)
840 : 80 : do_sql_command(conn, "SET extra_float_digits = 3");
841 : : else
842 : 0 : do_sql_command(conn, "SET extra_float_digits = 2");
843 : 80 : }
844 : :
845 : : /*
846 : : * Convenience subroutine to issue a non-data-returning SQL command to remote
847 : : */
848 : : void
849 : 1934 : do_sql_command(PGconn *conn, const char *sql)
850 : : {
851 : 1934 : do_sql_command_begin(conn, sql);
852 : 1934 : do_sql_command_end(conn, sql, false);
853 : 1931 : }
854 : :
855 : : static void
856 : 1952 : do_sql_command_begin(PGconn *conn, const char *sql)
857 : : {
858 [ - + ]: 1952 : if (!PQsendQuery(conn, sql))
859 : 0 : pgfdw_report_error(NULL, conn, sql);
860 : 1952 : }
861 : :
862 : : static void
863 : 1952 : do_sql_command_end(PGconn *conn, const char *sql, bool consume_input)
864 : : {
865 : : PGresult *res;
866 : :
867 : : /*
868 : : * If requested, consume whatever data is available from the socket. (Note
869 : : * that if all data is available, this allows pgfdw_get_result to call
870 : : * PQgetResult without forcing the overhead of WaitLatchOrSocket, which
871 : : * would be large compared to the overhead of PQconsumeInput.)
872 : : */
873 [ + + - + ]: 1952 : if (consume_input && !PQconsumeInput(conn))
874 : 0 : pgfdw_report_error(NULL, conn, sql);
875 : 1952 : res = pgfdw_get_result(conn);
876 [ + + ]: 1952 : if (PQresultStatus(res) != PGRES_COMMAND_OK)
877 : 3 : pgfdw_report_error(res, conn, sql);
878 : 1949 : PQclear(res);
879 : 1949 : }
880 : :
881 : : /*
882 : : * Start remote transaction or subtransaction, if needed.
883 : : *
884 : : * Note that we always use at least REPEATABLE READ in the remote session.
885 : : * This is so that, if a query initiates multiple scans of the same or
886 : : * different foreign tables, we will get snapshot-consistent results from
887 : : * those scans. A disadvantage is that we can't provide sane emulation of
888 : : * READ COMMITTED behavior --- it would be nice if we had some other way to
889 : : * control which remote queries share a snapshot.
890 : : *
891 : : * Note also that we always start the remote transaction with the same
892 : : * read/write and deferrable properties as the local transaction, and start
893 : : * the remote subtransaction with the same read/write property as the local
894 : : * subtransaction.
895 : : */
896 : : static void
897 : 2289 : begin_remote_xact(ConnCacheEntry *entry)
898 : : {
899 : 2289 : int curlevel = GetCurrentTransactionNestLevel();
900 : :
901 : : /*
902 : : * If the current local (sub)transaction is read-only, set the topmost
903 : : * read-only local transaction's nesting level if we haven't yet.
904 : : *
905 : : * Note: once it's set, it's retained until the topmost read-only local
906 : : * transaction is committed/aborted (see pgfdw_xact_callback and
907 : : * pgfdw_subxact_callback).
908 : : */
909 [ + + ]: 2289 : if (XactReadOnly)
910 : : {
911 [ + + ]: 10 : if (read_only_level == 0)
912 : 9 : read_only_level = GetTopReadOnlyTransactionNestLevel();
913 : : Assert(read_only_level > 0);
914 : : }
915 : : else
916 : : Assert(read_only_level == 0);
917 : :
918 : : /*
919 : : * Start main transaction if we haven't yet; otherwise, change the current
920 : : * remote (sub)transaction's read/write mode if needed.
921 : : */
922 [ + + ]: 2289 : if (entry->xact_depth <= 0)
923 : : {
924 : : /*
925 : : * This is the case when we haven't yet started a main transaction.
926 : : */
927 : : StringInfoData sql;
928 : 784 : bool ro = (read_only_level == 1);
929 : :
930 [ - + ]: 784 : elog(DEBUG3, "starting remote transaction on connection %p",
931 : : entry->conn);
932 : :
933 : 784 : initStringInfo(&sql);
934 : 784 : appendStringInfoString(&sql, "START TRANSACTION ISOLATION LEVEL ");
935 [ + + ]: 784 : if (IsolationIsSerializable())
936 : 3 : appendStringInfoString(&sql, "SERIALIZABLE");
937 : : else
938 : 781 : appendStringInfoString(&sql, "REPEATABLE READ");
939 [ + + ]: 784 : if (ro)
940 : 3 : appendStringInfoString(&sql, " READ ONLY");
941 [ + + ]: 784 : if (XactDeferrable)
942 : 2 : appendStringInfoString(&sql, " DEFERRABLE");
943 : 784 : entry->changing_xact_state = true;
944 : 784 : do_sql_command(entry->conn, sql.data);
945 : 783 : entry->xact_depth = 1;
946 [ + + ]: 783 : if (ro)
947 : : {
948 : : Assert(!entry->xact_read_only);
949 : 3 : entry->xact_read_only = true;
950 : : }
951 : 783 : entry->changing_xact_state = false;
952 : : }
953 [ + + ]: 1505 : else if (!entry->xact_read_only)
954 : : {
955 : : /*
956 : : * The remote (sub)transaction has been opened in read-write mode.
957 : : */
958 : : Assert(read_only_level == 0 ||
959 : : entry->xact_depth <= read_only_level);
960 : :
961 : : /*
962 : : * If its nesting depth matches read_only_level, it means that the
963 : : * local read-write (sub)transaction that started it has changed to
964 : : * read-only after that; in which case change it to read-only as well.
965 : : * Otherwise, the local (sub)transaction is still read-write, so there
966 : : * is no need to do anything.
967 : : */
968 [ + + ]: 1504 : if (entry->xact_depth == read_only_level)
969 : : {
970 : 4 : entry->changing_xact_state = true;
971 : 4 : do_sql_command(entry->conn, "SET transaction_read_only = on");
972 : 4 : entry->xact_read_only = true;
973 : 4 : entry->changing_xact_state = false;
974 : : }
975 : : }
976 : : else
977 : : {
978 : : /*
979 : : * The remote (sub)transaction has been opened in read-only mode.
980 : : */
981 : : Assert(read_only_level > 0 &&
982 : : entry->xact_depth >= read_only_level);
983 : :
984 : : /*
985 : : * The local read-only (sub)transaction that started it is guaranteed
986 : : * to be still read-only (see check_transaction_read_only), so there
987 : : * is no need to do anything.
988 : : */
989 : : }
990 : :
991 : : /*
992 : : * If we're in a subtransaction, stack up savepoints to match our level.
993 : : * This ensures we can rollback just the desired effects when a
994 : : * subtransaction aborts.
995 : : */
996 [ + + ]: 2309 : while (entry->xact_depth < curlevel)
997 : : {
998 : : StringInfoData sql;
999 : 22 : bool ro = (entry->xact_depth + 1 == read_only_level);
1000 : :
1001 : 22 : initStringInfo(&sql);
1002 : 22 : appendStringInfo(&sql, "SAVEPOINT s%d", entry->xact_depth + 1);
1003 [ + + ]: 22 : if (ro)
1004 : 2 : appendStringInfoString(&sql, "; SET transaction_read_only = on");
1005 : 22 : entry->changing_xact_state = true;
1006 : 22 : do_sql_command(entry->conn, sql.data);
1007 : 21 : entry->xact_depth++;
1008 [ + + ]: 21 : if (ro)
1009 : : {
1010 : : Assert(!entry->xact_read_only);
1011 : 2 : entry->xact_read_only = true;
1012 : : }
1013 : 21 : entry->changing_xact_state = false;
1014 : : }
1015 : 2287 : }
1016 : :
1017 : : /*
1018 : : * Release connection reference count created by calling GetConnection.
1019 : : */
1020 : : void
1021 : 2212 : ReleaseConnection(PGconn *conn)
1022 : : {
1023 : : /*
1024 : : * Currently, we don't actually track connection references because all
1025 : : * cleanup is managed on a transaction or subtransaction basis instead. So
1026 : : * there's nothing to do here.
1027 : : */
1028 : 2212 : }
1029 : :
1030 : : /*
1031 : : * Assign a "unique" number for a cursor.
1032 : : *
1033 : : * These really only need to be unique per connection within a transaction.
1034 : : * For the moment we ignore the per-connection point and assign them across
1035 : : * all connections in the transaction, but we ask for the connection to be
1036 : : * supplied in case we want to refine that.
1037 : : *
1038 : : * Note that even if wraparound happens in a very long transaction, actual
1039 : : * collisions are highly improbable; just be sure to use %u not %d to print.
1040 : : */
1041 : : unsigned int
1042 : 581 : GetCursorNumber(PGconn *conn)
1043 : : {
1044 : 581 : return ++cursor_number;
1045 : : }
1046 : :
1047 : : /*
1048 : : * Assign a "unique" number for a prepared statement.
1049 : : *
1050 : : * This works much like GetCursorNumber, except that we never reset the counter
1051 : : * within a session. That's because we can't be 100% sure we've gotten rid
1052 : : * of all prepared statements on all connections, and it's not really worth
1053 : : * increasing the risk of prepared-statement name collisions by resetting.
1054 : : */
1055 : : unsigned int
1056 : 188 : GetPrepStmtNumber(PGconn *conn)
1057 : : {
1058 : 188 : return ++prep_stmt_number;
1059 : : }
1060 : :
1061 : : /*
1062 : : * Submit a query and wait for the result.
1063 : : *
1064 : : * Since we don't use non-blocking mode, this can't process interrupts while
1065 : : * pushing the query text to the server. That risk is relatively small, so we
1066 : : * ignore that for now.
1067 : : *
1068 : : * Caller is responsible for the error handling on the result.
1069 : : */
1070 : : PGresult *
1071 : 4194 : pgfdw_exec_query(PGconn *conn, const char *query, PgFdwConnState *state)
1072 : : {
1073 : : /* First, process a pending asynchronous request, if any. */
1074 [ + + + + ]: 4194 : if (state && state->pendingAreq)
1075 : 4 : process_pending_request(state->pendingAreq);
1076 : :
1077 [ + + ]: 4194 : if (!PQsendQuery(conn, query))
1078 : 1 : return NULL;
1079 : 4193 : return pgfdw_get_result(conn);
1080 : : }
1081 : :
1082 : : /*
1083 : : * Wrap libpqsrv_get_result_last(), adding wait event.
1084 : : *
1085 : : * Caller is responsible for the error handling on the result.
1086 : : */
1087 : : PGresult *
1088 : 8472 : pgfdw_get_result(PGconn *conn)
1089 : : {
1090 : 8472 : return libpqsrv_get_result_last(conn, pgfdw_we_get_result);
1091 : : }
1092 : :
1093 : : /*
1094 : : * Report an error we got from the remote server.
1095 : : *
1096 : : * Callers should use pgfdw_report_error() to throw an error, or use
1097 : : * pgfdw_report() for lesser message levels. (We make this distinction
1098 : : * so that pgfdw_report_error() can be marked noreturn.)
1099 : : *
1100 : : * res: PGresult containing the error (might be NULL)
1101 : : * conn: connection we did the query on
1102 : : * sql: NULL, or text of remote command we tried to execute
1103 : : *
1104 : : * If "res" is not NULL, it'll be PQclear'ed here (unless we throw error,
1105 : : * in which case memory context cleanup will clear it eventually).
1106 : : *
1107 : : * Note: callers that choose not to throw ERROR for a remote error are
1108 : : * responsible for making sure that the associated ConnCacheEntry gets
1109 : : * marked with have_error = true.
1110 : : */
1111 : : void
1112 : 26 : pgfdw_report_error(PGresult *res, PGconn *conn, const char *sql)
1113 : : {
1114 : 26 : pgfdw_report_internal(ERROR, res, conn, sql);
1115 : 0 : pg_unreachable();
1116 : : }
1117 : :
1118 : : void
1119 : 3 : pgfdw_report(int elevel, PGresult *res, PGconn *conn, const char *sql)
1120 : : {
1121 : : Assert(elevel < ERROR); /* use pgfdw_report_error for that */
1122 : 3 : pgfdw_report_internal(elevel, res, conn, sql);
1123 : 3 : }
1124 : :
1125 : : static void
1126 : 29 : pgfdw_report_internal(int elevel, PGresult *res, PGconn *conn,
1127 : : const char *sql)
1128 : : {
1129 : 29 : char *diag_sqlstate = PQresultErrorField(res, PG_DIAG_SQLSTATE);
1130 : 29 : char *message_primary = PQresultErrorField(res, PG_DIAG_MESSAGE_PRIMARY);
1131 : 29 : char *message_detail = PQresultErrorField(res, PG_DIAG_MESSAGE_DETAIL);
1132 : 29 : char *message_hint = PQresultErrorField(res, PG_DIAG_MESSAGE_HINT);
1133 : 29 : char *message_context = PQresultErrorField(res, PG_DIAG_CONTEXT);
1134 : : int sqlstate;
1135 : :
1136 [ + + ]: 29 : if (diag_sqlstate)
1137 : 22 : sqlstate = MAKE_SQLSTATE(diag_sqlstate[0],
1138 : : diag_sqlstate[1],
1139 : : diag_sqlstate[2],
1140 : : diag_sqlstate[3],
1141 : : diag_sqlstate[4]);
1142 : : else
1143 : 7 : sqlstate = ERRCODE_CONNECTION_FAILURE;
1144 : :
1145 : : /*
1146 : : * If we don't get a message from the PGresult, try the PGconn. This is
1147 : : * needed because for connection-level failures, PQgetResult may just
1148 : : * return NULL, not a PGresult at all.
1149 : : */
1150 [ + + ]: 29 : if (message_primary == NULL)
1151 : 7 : message_primary = pchomp(PQerrorMessage(conn));
1152 : :
1153 [ + - + - : 29 : ereport(elevel,
+ - + + +
+ + + +
- ]
1154 : : (errcode(sqlstate),
1155 : : (message_primary != NULL && message_primary[0] != '\0') ?
1156 : : errmsg_internal("%s", message_primary) :
1157 : : errmsg("could not obtain message string for remote error"),
1158 : : message_detail ? errdetail_internal("%s", message_detail) : 0,
1159 : : message_hint ? errhint("%s", message_hint) : 0,
1160 : : message_context ? errcontext("%s", message_context) : 0,
1161 : : sql ? errcontext("remote SQL command: %s", sql) : 0));
1162 : 3 : PQclear(res);
1163 : 3 : }
1164 : :
1165 : : /*
1166 : : * pgfdw_xact_callback --- cleanup at main-transaction end.
1167 : : *
1168 : : * This runs just late enough that it must not enter user-defined code
1169 : : * locally. (Entering such code on the remote side is fine. Its remote
1170 : : * COMMIT TRANSACTION may run deferred triggers.)
1171 : : */
1172 : : static void
1173 : 4342 : pgfdw_xact_callback(XactEvent event, void *arg)
1174 : : {
1175 : : HASH_SEQ_STATUS scan;
1176 : : ConnCacheEntry *entry;
1177 : 4342 : List *pending_entries = NIL;
1178 : 4342 : List *cancel_requested = NIL;
1179 : :
1180 : : /* Quick exit if no connections were touched in this transaction. */
1181 [ + + ]: 4342 : if (!xact_got_connection)
1182 : 3590 : return;
1183 : :
1184 : : /*
1185 : : * Scan all connection cache entries to find open remote transactions, and
1186 : : * close them.
1187 : : */
1188 : 752 : hash_seq_init(&scan, ConnectionHash);
1189 [ + + ]: 3969 : while ((entry = (ConnCacheEntry *) hash_seq_search(&scan)))
1190 : : {
1191 : : PGresult *res;
1192 : :
1193 : : /* Ignore cache entry if no open connection right now */
1194 [ + + ]: 3218 : if (entry->conn == NULL)
1195 : 1886 : continue;
1196 : :
1197 : : /* If it has an open remote transaction, try to close it */
1198 [ + + ]: 1332 : if (entry->xact_depth > 0)
1199 : : {
1200 [ - + ]: 784 : elog(DEBUG3, "closing remote transaction on connection %p",
1201 : : entry->conn);
1202 : :
1203 [ + + - + : 784 : switch (event)
- ]
1204 : : {
1205 : 723 : case XACT_EVENT_PARALLEL_PRE_COMMIT:
1206 : : case XACT_EVENT_PRE_COMMIT:
1207 : :
1208 : : /*
1209 : : * If abort cleanup previously failed for this connection,
1210 : : * we can't issue any more commands against it.
1211 : : */
1212 : 723 : pgfdw_reject_incomplete_xact_state_change(entry);
1213 : :
1214 : : /* Commit all remote transactions during pre-commit */
1215 : 723 : entry->changing_xact_state = true;
1216 [ + + ]: 723 : if (entry->parallel_commit)
1217 : : {
1218 : 16 : do_sql_command_begin(entry->conn, "COMMIT TRANSACTION");
1219 : 16 : pending_entries = lappend(pending_entries, entry);
1220 : 16 : continue;
1221 : : }
1222 : 707 : do_sql_command(entry->conn, "COMMIT TRANSACTION");
1223 : 707 : entry->changing_xact_state = false;
1224 : :
1225 : : /*
1226 : : * If there were any errors in subtransactions, and we
1227 : : * made prepared statements, do a DEALLOCATE ALL to make
1228 : : * sure we get rid of all prepared statements. This is
1229 : : * annoying and not terribly bulletproof, but it's
1230 : : * probably not worth trying harder.
1231 : : *
1232 : : * DEALLOCATE ALL only exists in 8.3 and later, so this
1233 : : * constrains how old a server postgres_fdw can
1234 : : * communicate with. We intentionally ignore errors in
1235 : : * the DEALLOCATE, so that we can hobble along to some
1236 : : * extent with older servers (leaking prepared statements
1237 : : * as we go; but we don't really support update operations
1238 : : * pre-8.3 anyway).
1239 : : */
1240 [ + + - + ]: 707 : if (entry->have_prep_stmt && entry->have_error)
1241 : : {
1242 : 0 : res = pgfdw_exec_query(entry->conn, "DEALLOCATE ALL",
1243 : : NULL);
1244 : 0 : PQclear(res);
1245 : : }
1246 : 707 : entry->have_prep_stmt = false;
1247 : 707 : entry->have_error = false;
1248 : 707 : break;
1249 : 1 : case XACT_EVENT_PRE_PREPARE:
1250 : :
1251 : : /*
1252 : : * We disallow any remote transactions, since it's not
1253 : : * very reasonable to hold them open until the prepared
1254 : : * transaction is committed. For the moment, throw error
1255 : : * unconditionally; later we might allow read-only cases.
1256 : : * Note that the error will cause us to come right back
1257 : : * here with event == XACT_EVENT_ABORT, so we'll clean up
1258 : : * the connection state at that point.
1259 : : */
1260 [ + - ]: 1 : ereport(ERROR,
1261 : : (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
1262 : : errmsg("cannot PREPARE a transaction that has operated on postgres_fdw foreign tables")));
1263 : : break;
1264 : 0 : case XACT_EVENT_PARALLEL_COMMIT:
1265 : : case XACT_EVENT_COMMIT:
1266 : : case XACT_EVENT_PREPARE:
1267 : : /* Pre-commit should have closed the open transaction */
1268 [ # # ]: 0 : elog(ERROR, "missed cleaning up connection during pre-commit");
1269 : : break;
1270 : 60 : case XACT_EVENT_PARALLEL_ABORT:
1271 : : case XACT_EVENT_ABORT:
1272 : : /* Rollback all remote transactions during abort */
1273 [ + + ]: 60 : if (entry->parallel_abort)
1274 : : {
1275 [ + - ]: 4 : if (pgfdw_abort_cleanup_begin(entry, true,
1276 : : &pending_entries,
1277 : : &cancel_requested))
1278 : 4 : continue;
1279 : : }
1280 : : else
1281 : 56 : pgfdw_abort_cleanup(entry, true);
1282 : 56 : break;
1283 : : }
1284 : : }
1285 : :
1286 : : /* Reset state to show we're out of a transaction */
1287 : 1311 : pgfdw_reset_xact_state(entry, true);
1288 : : }
1289 : :
1290 : : /* If there are any pending connections, finish cleaning them up */
1291 [ + + - + ]: 751 : if (pending_entries || cancel_requested)
1292 : : {
1293 [ + - + + ]: 15 : if (event == XACT_EVENT_PARALLEL_PRE_COMMIT ||
1294 : : event == XACT_EVENT_PRE_COMMIT)
1295 : : {
1296 : : Assert(cancel_requested == NIL);
1297 : 13 : pgfdw_finish_pre_commit_cleanup(pending_entries);
1298 : : }
1299 : : else
1300 : : {
1301 : : Assert(event == XACT_EVENT_PARALLEL_ABORT ||
1302 : : event == XACT_EVENT_ABORT);
1303 : 2 : pgfdw_finish_abort_cleanup(pending_entries, cancel_requested,
1304 : : true);
1305 : : }
1306 : : }
1307 : :
1308 : : /*
1309 : : * Regardless of the event type, we can now mark ourselves as out of the
1310 : : * transaction. (Note: if we are here during PRE_COMMIT or PRE_PREPARE,
1311 : : * this saves a useless scan of the hashtable during COMMIT or PREPARE.)
1312 : : */
1313 : 751 : xact_got_connection = false;
1314 : :
1315 : : /* Also reset cursor numbering for next transaction */
1316 : 751 : cursor_number = 0;
1317 : :
1318 : : /* Likewise for read_only_level */
1319 : 751 : read_only_level = 0;
1320 : : }
1321 : :
1322 : : /*
1323 : : * pgfdw_subxact_callback --- cleanup at subtransaction end.
1324 : : */
1325 : : static void
1326 : 72 : pgfdw_subxact_callback(SubXactEvent event, SubTransactionId mySubid,
1327 : : SubTransactionId parentSubid, void *arg)
1328 : : {
1329 : : HASH_SEQ_STATUS scan;
1330 : : ConnCacheEntry *entry;
1331 : : int curlevel;
1332 : 72 : List *pending_entries = NIL;
1333 : 72 : List *cancel_requested = NIL;
1334 : :
1335 : : /* Nothing to do at subxact start, nor after commit. */
1336 [ + + + + ]: 72 : if (!(event == SUBXACT_EVENT_PRE_COMMIT_SUB ||
1337 : : event == SUBXACT_EVENT_ABORT_SUB))
1338 : 43 : return;
1339 : :
1340 : : /* Quick exit if no connections were touched in this transaction. */
1341 [ - + ]: 29 : if (!xact_got_connection)
1342 : 0 : return;
1343 : :
1344 : : /*
1345 : : * Scan all connection cache entries to find open remote subtransactions
1346 : : * of the current level, and close them.
1347 : : */
1348 : 29 : curlevel = GetCurrentTransactionNestLevel();
1349 : 29 : hash_seq_init(&scan, ConnectionHash);
1350 [ + + ]: 242 : while ((entry = (ConnCacheEntry *) hash_seq_search(&scan)))
1351 : : {
1352 : : char sql[100];
1353 : :
1354 : : /*
1355 : : * We only care about connections with open remote subtransactions of
1356 : : * the current level.
1357 : : */
1358 [ + + + + ]: 213 : if (entry->conn == NULL || entry->xact_depth < curlevel)
1359 : 198 : continue;
1360 : :
1361 [ - + ]: 21 : if (entry->xact_depth > curlevel)
1362 [ # # ]: 0 : elog(ERROR, "missed cleaning up remote subtransaction at level %d",
1363 : : entry->xact_depth);
1364 : :
1365 [ + + ]: 21 : if (event == SUBXACT_EVENT_PRE_COMMIT_SUB)
1366 : : {
1367 : : /*
1368 : : * If abort cleanup previously failed for this connection, we
1369 : : * can't issue any more commands against it.
1370 : : */
1371 : 7 : pgfdw_reject_incomplete_xact_state_change(entry);
1372 : :
1373 : : /* Commit all remote subtransactions during pre-commit */
1374 : 7 : snprintf(sql, sizeof(sql), "RELEASE SAVEPOINT s%d", curlevel);
1375 : 7 : entry->changing_xact_state = true;
1376 [ + + ]: 7 : if (entry->parallel_commit)
1377 : : {
1378 : 2 : do_sql_command_begin(entry->conn, sql);
1379 : 2 : pending_entries = lappend(pending_entries, entry);
1380 : 2 : continue;
1381 : : }
1382 : 5 : do_sql_command(entry->conn, sql);
1383 : 5 : entry->changing_xact_state = false;
1384 : : }
1385 : : else
1386 : : {
1387 : : /* Rollback all remote subtransactions during abort */
1388 [ + + ]: 14 : if (entry->parallel_abort)
1389 : : {
1390 [ + - ]: 4 : if (pgfdw_abort_cleanup_begin(entry, false,
1391 : : &pending_entries,
1392 : : &cancel_requested))
1393 : 4 : continue;
1394 : : }
1395 : : else
1396 : 10 : pgfdw_abort_cleanup(entry, false);
1397 : : }
1398 : :
1399 : : /* OK, we're outta that level of subtransaction */
1400 : 15 : pgfdw_reset_xact_state(entry, false);
1401 : : }
1402 : :
1403 : : /* If there are any pending connections, finish cleaning them up */
1404 [ + + - + ]: 29 : if (pending_entries || cancel_requested)
1405 : : {
1406 [ + + ]: 3 : if (event == SUBXACT_EVENT_PRE_COMMIT_SUB)
1407 : : {
1408 : : Assert(cancel_requested == NIL);
1409 : 1 : pgfdw_finish_pre_subcommit_cleanup(pending_entries, curlevel);
1410 : : }
1411 : : else
1412 : : {
1413 : : Assert(event == SUBXACT_EVENT_ABORT_SUB);
1414 : 2 : pgfdw_finish_abort_cleanup(pending_entries, cancel_requested,
1415 : : false);
1416 : : }
1417 : : }
1418 : :
1419 : : /* If in read_only_level, reset it */
1420 [ + + ]: 29 : if (curlevel == read_only_level)
1421 : 3 : read_only_level = 0;
1422 : : }
1423 : :
1424 : : /*
1425 : : * Connection invalidation callback function
1426 : : *
1427 : : * After a change to a pg_foreign_server or pg_user_mapping catalog entry,
1428 : : * close connections depending on that entry immediately if current transaction
1429 : : * has not used those connections yet. Otherwise, mark those connections as
1430 : : * invalid and then make pgfdw_xact_callback() close them at the end of current
1431 : : * transaction, since they cannot be closed in the midst of the transaction
1432 : : * using them. Closed connections will be remade at the next opportunity if
1433 : : * necessary.
1434 : : *
1435 : : * Although most cache invalidation callbacks blow away all the related stuff
1436 : : * regardless of the given hashvalue, connections are expensive enough that
1437 : : * it's worth trying to avoid that.
1438 : : *
1439 : : * NB: We could avoid unnecessary disconnection more strictly by examining
1440 : : * individual option values, but it seems too much effort for the gain.
1441 : : */
1442 : : static void
1443 : 188 : pgfdw_inval_callback(Datum arg, SysCacheIdentifier cacheid, uint32 hashvalue)
1444 : : {
1445 : : HASH_SEQ_STATUS scan;
1446 : : ConnCacheEntry *entry;
1447 : :
1448 : : Assert(cacheid == FOREIGNSERVEROID || cacheid == USERMAPPINGOID);
1449 : :
1450 : : /* ConnectionHash must exist already, if we're registered */
1451 : 188 : hash_seq_init(&scan, ConnectionHash);
1452 [ + + ]: 1222 : while ((entry = (ConnCacheEntry *) hash_seq_search(&scan)))
1453 : : {
1454 : : /* Ignore invalid entries */
1455 [ + + ]: 1034 : if (entry->conn == NULL)
1456 : 838 : continue;
1457 : :
1458 : : /* hashvalue == 0 means a cache reset, must clear all state */
1459 [ + - + + ]: 196 : if (hashvalue == 0 ||
1460 : 140 : (cacheid == FOREIGNSERVEROID &&
1461 [ + + + + ]: 196 : entry->server_hashvalue == hashvalue) ||
1462 : 56 : (cacheid == USERMAPPINGOID &&
1463 [ + + ]: 56 : entry->mapping_hashvalue == hashvalue))
1464 : : {
1465 : : /*
1466 : : * Close the connection immediately if it's not used yet in this
1467 : : * transaction. Otherwise mark it as invalid so that
1468 : : * pgfdw_xact_callback() can close it at the end of this
1469 : : * transaction.
1470 : : */
1471 [ + + ]: 59 : if (entry->xact_depth == 0)
1472 : : {
1473 [ - + ]: 56 : elog(DEBUG3, "discarding connection %p", entry->conn);
1474 : 56 : disconnect_pg_server(entry);
1475 : : }
1476 : : else
1477 : 3 : entry->invalidated = true;
1478 : : }
1479 : : }
1480 : 188 : }
1481 : :
1482 : : /*
1483 : : * Raise an error if the given connection cache entry is marked as being
1484 : : * in the middle of an xact state change. This should be called at which no
1485 : : * such change is expected to be in progress; if one is found to be in
1486 : : * progress, it means that we aborted in the middle of a previous state change
1487 : : * and now don't know what the remote transaction state actually is.
1488 : : * Such connections can't safely be further used. Re-establishing the
1489 : : * connection would change the snapshot and roll back any writes already
1490 : : * performed, so that's not an option, either. Thus, we must abort.
1491 : : *
1492 : : * Note: there might be open cursors that use the connection, so even if the
1493 : : * connection cache entry is marked as such, we will retain it until abort
1494 : : * cleanup of the main transaction, to ensure such open cursors can safely
1495 : : * refer to the PGconn for the connection.
1496 : : */
1497 : : static void
1498 : 3027 : pgfdw_reject_incomplete_xact_state_change(ConnCacheEntry *entry)
1499 : : {
1500 : : ForeignServer *server;
1501 : :
1502 : : /* nothing to do for inactive entries and entries of sane state */
1503 [ + + + + ]: 3027 : if (entry->conn == NULL || !entry->changing_xact_state)
1504 : 3025 : return;
1505 : :
1506 : : /* find server name to be shown in the message below */
1507 : 2 : server = GetForeignServer(entry->serverid);
1508 : :
1509 [ + - ]: 2 : ereport(ERROR,
1510 : : (errcode(ERRCODE_CONNECTION_EXCEPTION),
1511 : : errmsg("connection to server \"%s\" cannot be used due to abort cleanup failure",
1512 : : server->servername)));
1513 : : }
1514 : :
1515 : : /*
1516 : : * Reset state to show we're out of a (sub)transaction.
1517 : : */
1518 : : static void
1519 : 1352 : pgfdw_reset_xact_state(ConnCacheEntry *entry, bool toplevel)
1520 : : {
1521 [ + + ]: 1352 : if (toplevel)
1522 : : {
1523 : : /* Reset state to show we're out of a transaction */
1524 : 1331 : entry->xact_depth = 0;
1525 : :
1526 : : /* Reset xact r/o state */
1527 : 1331 : entry->xact_read_only = false;
1528 : :
1529 : : /*
1530 : : * If the connection isn't in a good idle state, it is marked as
1531 : : * invalid or keep_connections option of its server is disabled, then
1532 : : * discard it to recover. Next GetConnection will open a new
1533 : : * connection.
1534 : : */
1535 [ + + + - ]: 2658 : if (PQstatus(entry->conn) != CONNECTION_OK ||
1536 : 1327 : PQtransactionStatus(entry->conn) != PQTRANS_IDLE ||
1537 [ + - ]: 1327 : entry->changing_xact_state ||
1538 [ + + ]: 1327 : entry->invalidated ||
1539 [ + + ]: 1325 : !entry->keep_connections)
1540 : : {
1541 [ - + ]: 7 : elog(DEBUG3, "discarding connection %p", entry->conn);
1542 : 7 : disconnect_pg_server(entry);
1543 : : }
1544 : : }
1545 : : else
1546 : : {
1547 : : /* Reset state to show we're out of a subtransaction */
1548 : 21 : entry->xact_depth--;
1549 : :
1550 : : /* If in read_only_level, reset xact r/o state */
1551 [ + + ]: 21 : if (entry->xact_depth + 1 == read_only_level)
1552 : 4 : entry->xact_read_only = false;
1553 : : }
1554 : 1352 : }
1555 : :
1556 : : /*
1557 : : * Cancel the currently-in-progress query (whose query text we do not have)
1558 : : * and ignore the result. Returns true if we successfully cancel the query
1559 : : * and discard any pending result, and false if not.
1560 : : *
1561 : : * It's not a huge problem if we throw an ERROR here, but if we get into error
1562 : : * recursion trouble, we'll end up slamming the connection shut, which will
1563 : : * necessitate failing the entire toplevel transaction even if subtransactions
1564 : : * were used. Try to use WARNING where we can.
1565 : : *
1566 : : * XXX: if the query was one sent by fetch_more_data_begin(), we could get the
1567 : : * query text from the pendingAreq saved in the per-connection state, then
1568 : : * report the query using it.
1569 : : */
1570 : : static bool
1571 : 2 : pgfdw_cancel_query(PGconn *conn)
1572 : : {
1573 : 2 : TimestampTz now = GetCurrentTimestamp();
1574 : : TimestampTz endtime;
1575 : : TimestampTz retrycanceltime;
1576 : :
1577 : : /*
1578 : : * If it takes too long to cancel the query and discard the result, assume
1579 : : * the connection is dead.
1580 : : */
1581 : 2 : endtime = TimestampTzPlusMilliseconds(now, CONNECTION_CLEANUP_TIMEOUT);
1582 : :
1583 : : /*
1584 : : * Also, lose patience and re-issue the cancel request after a little bit.
1585 : : * (This serves to close some race conditions.)
1586 : : */
1587 : 2 : retrycanceltime = TimestampTzPlusMilliseconds(now, RETRY_CANCEL_TIMEOUT);
1588 : :
1589 [ - + ]: 2 : if (!pgfdw_cancel_query_begin(conn, endtime))
1590 : 0 : return false;
1591 : 2 : return pgfdw_cancel_query_end(conn, endtime, retrycanceltime, false);
1592 : : }
1593 : :
1594 : : /*
1595 : : * Submit a cancel request to the given connection, waiting only until
1596 : : * the given time.
1597 : : *
1598 : : * We sleep interruptibly until we receive confirmation that the cancel
1599 : : * request has been accepted, and if it is, return true; if the timeout
1600 : : * lapses without that, or the request fails for whatever reason, return
1601 : : * false.
1602 : : */
1603 : : static bool
1604 : 2 : pgfdw_cancel_query_begin(PGconn *conn, TimestampTz endtime)
1605 : : {
1606 : 2 : const char *errormsg = libpqsrv_cancel(conn, endtime);
1607 : :
1608 [ - + ]: 2 : if (errormsg != NULL)
1609 [ # # ]: 0 : ereport(WARNING,
1610 : : errcode(ERRCODE_CONNECTION_FAILURE),
1611 : : errmsg("could not send cancel request: %s", errormsg));
1612 : :
1613 : 2 : return errormsg == NULL;
1614 : : }
1615 : :
1616 : : static bool
1617 : 2 : pgfdw_cancel_query_end(PGconn *conn, TimestampTz endtime,
1618 : : TimestampTz retrycanceltime, bool consume_input)
1619 : : {
1620 : : PGresult *result;
1621 : : bool timed_out;
1622 : :
1623 : : /*
1624 : : * If requested, consume whatever data is available from the socket. (Note
1625 : : * that if all data is available, this allows pgfdw_get_cleanup_result to
1626 : : * call PQgetResult without forcing the overhead of WaitLatchOrSocket,
1627 : : * which would be large compared to the overhead of PQconsumeInput.)
1628 : : */
1629 [ - + - - ]: 2 : if (consume_input && !PQconsumeInput(conn))
1630 : : {
1631 [ # # ]: 0 : ereport(WARNING,
1632 : : (errcode(ERRCODE_CONNECTION_FAILURE),
1633 : : errmsg("could not get result of cancel request: %s",
1634 : : pchomp(PQerrorMessage(conn)))));
1635 : 0 : return false;
1636 : : }
1637 : :
1638 : : /* Get and discard the result of the query. */
1639 [ - + ]: 2 : if (pgfdw_get_cleanup_result(conn, endtime, retrycanceltime,
1640 : : &result, &timed_out))
1641 : : {
1642 [ # # ]: 0 : if (timed_out)
1643 [ # # ]: 0 : ereport(WARNING,
1644 : : (errmsg("could not get result of cancel request due to timeout")));
1645 : : else
1646 [ # # ]: 0 : ereport(WARNING,
1647 : : (errcode(ERRCODE_CONNECTION_FAILURE),
1648 : : errmsg("could not get result of cancel request: %s",
1649 : : pchomp(PQerrorMessage(conn)))));
1650 : :
1651 : 0 : return false;
1652 : : }
1653 : 2 : PQclear(result);
1654 : :
1655 : 2 : return true;
1656 : : }
1657 : :
1658 : : /*
1659 : : * Submit a query during (sub)abort cleanup and wait up to 30 seconds for the
1660 : : * result. If the query is executed without error, the return value is true.
1661 : : * If the query is executed successfully but returns an error, the return
1662 : : * value is true if and only if ignore_errors is set. If the query can't be
1663 : : * sent or times out, the return value is false.
1664 : : *
1665 : : * It's not a huge problem if we throw an ERROR here, but if we get into error
1666 : : * recursion trouble, we'll end up slamming the connection shut, which will
1667 : : * necessitate failing the entire toplevel transaction even if subtransactions
1668 : : * were used. Try to use WARNING where we can.
1669 : : */
1670 : : static bool
1671 : 88 : pgfdw_exec_cleanup_query(PGconn *conn, const char *query, bool ignore_errors)
1672 : : {
1673 : : TimestampTz endtime;
1674 : :
1675 : : /*
1676 : : * If it takes too long to execute a cleanup query, assume the connection
1677 : : * is dead. It's fairly likely that this is why we aborted in the first
1678 : : * place (e.g. statement timeout, user cancel), so the timeout shouldn't
1679 : : * be too long.
1680 : : */
1681 : 88 : endtime = TimestampTzPlusMilliseconds(GetCurrentTimestamp(),
1682 : : CONNECTION_CLEANUP_TIMEOUT);
1683 : :
1684 [ - + ]: 88 : if (!pgfdw_exec_cleanup_query_begin(conn, query))
1685 : 0 : return false;
1686 : 88 : return pgfdw_exec_cleanup_query_end(conn, query, endtime,
1687 : : false, ignore_errors);
1688 : : }
1689 : :
1690 : : static bool
1691 : 100 : pgfdw_exec_cleanup_query_begin(PGconn *conn, const char *query)
1692 : : {
1693 : : Assert(query != NULL);
1694 : :
1695 : : /*
1696 : : * Submit a query. Since we don't use non-blocking mode, this also can
1697 : : * block. But its risk is relatively small, so we ignore that for now.
1698 : : */
1699 [ - + ]: 100 : if (!PQsendQuery(conn, query))
1700 : : {
1701 : 0 : pgfdw_report(WARNING, NULL, conn, query);
1702 : 0 : return false;
1703 : : }
1704 : :
1705 : 100 : return true;
1706 : : }
1707 : :
1708 : : static bool
1709 : 100 : pgfdw_exec_cleanup_query_end(PGconn *conn, const char *query,
1710 : : TimestampTz endtime, bool consume_input,
1711 : : bool ignore_errors)
1712 : : {
1713 : : PGresult *result;
1714 : : bool timed_out;
1715 : :
1716 : : Assert(query != NULL);
1717 : :
1718 : : /*
1719 : : * If requested, consume whatever data is available from the socket. (Note
1720 : : * that if all data is available, this allows pgfdw_get_cleanup_result to
1721 : : * call PQgetResult without forcing the overhead of WaitLatchOrSocket,
1722 : : * which would be large compared to the overhead of PQconsumeInput.)
1723 : : */
1724 [ + + - + ]: 100 : if (consume_input && !PQconsumeInput(conn))
1725 : : {
1726 : 0 : pgfdw_report(WARNING, NULL, conn, query);
1727 : 0 : return false;
1728 : : }
1729 : :
1730 : : /* Get the result of the query. */
1731 [ + + ]: 100 : if (pgfdw_get_cleanup_result(conn, endtime, endtime, &result, &timed_out))
1732 : : {
1733 [ - + ]: 3 : if (timed_out)
1734 [ # # ]: 0 : ereport(WARNING,
1735 : : (errmsg("could not get query result due to timeout"),
1736 : : errcontext("remote SQL command: %s", query)));
1737 : : else
1738 : 3 : pgfdw_report(WARNING, NULL, conn, query);
1739 : :
1740 : 3 : return false;
1741 : : }
1742 : :
1743 : : /* Issue a warning if not successful. */
1744 [ - + ]: 97 : if (PQresultStatus(result) != PGRES_COMMAND_OK)
1745 : : {
1746 : 0 : pgfdw_report(WARNING, result, conn, query);
1747 : 0 : return ignore_errors;
1748 : : }
1749 : 97 : PQclear(result);
1750 : :
1751 : 97 : return true;
1752 : : }
1753 : :
1754 : : /*
1755 : : * Get, during abort cleanup, the result of a query that is in progress.
1756 : : * This might be a query that is being interrupted by a cancel request or by
1757 : : * transaction abort, or it might be a query that was initiated as part of
1758 : : * transaction abort to get the remote side back to the appropriate state.
1759 : : *
1760 : : * endtime is the time at which we should give up and assume the remote side
1761 : : * is dead. retrycanceltime is the time at which we should issue a fresh
1762 : : * cancel request (pass the same value as endtime if this is not wanted).
1763 : : *
1764 : : * Returns true if the timeout expired or connection trouble occurred,
1765 : : * false otherwise. Sets *result except in case of a true result.
1766 : : * Sets *timed_out to true only when the timeout expired.
1767 : : */
1768 : : static bool
1769 : 102 : pgfdw_get_cleanup_result(PGconn *conn, TimestampTz endtime,
1770 : : TimestampTz retrycanceltime,
1771 : : PGresult **result,
1772 : : bool *timed_out)
1773 : : {
1774 : 102 : bool failed = false;
1775 : 102 : PGresult *last_res = NULL;
1776 : 102 : int canceldelta = RETRY_CANCEL_TIMEOUT * 2;
1777 : :
1778 : 102 : *result = NULL;
1779 : 102 : *timed_out = false;
1780 : : for (;;)
1781 : 114 : {
1782 : : PGresult *res;
1783 : :
1784 [ + + ]: 308 : while (PQisBusy(conn))
1785 : : {
1786 : : int wc;
1787 : 95 : TimestampTz now = GetCurrentTimestamp();
1788 : : long cur_timeout;
1789 : :
1790 : : /* If timeout has expired, give up. */
1791 [ - + ]: 95 : if (now >= endtime)
1792 : : {
1793 : 0 : *timed_out = true;
1794 : 0 : failed = true;
1795 : 0 : goto exit;
1796 : : }
1797 : :
1798 : : /* If we need to re-issue the cancel request, do that. */
1799 [ - + ]: 95 : if (now >= retrycanceltime)
1800 : : {
1801 : : /* We ignore failure to issue the repeated request. */
1802 : 0 : (void) libpqsrv_cancel(conn, endtime);
1803 : :
1804 : : /* Recompute "now" in case that took measurable time. */
1805 : 0 : now = GetCurrentTimestamp();
1806 : :
1807 : : /* Adjust re-cancel timeout in increasing steps. */
1808 : 0 : retrycanceltime = TimestampTzPlusMilliseconds(now,
1809 : : canceldelta);
1810 : 0 : canceldelta += canceldelta;
1811 : : }
1812 : :
1813 : : /* If timeout has expired, give up, else get sleep time. */
1814 : 95 : cur_timeout = TimestampDifferenceMilliseconds(now,
1815 : : Min(endtime,
1816 : : retrycanceltime));
1817 [ - + ]: 95 : if (cur_timeout <= 0)
1818 : : {
1819 : 0 : *timed_out = true;
1820 : 0 : failed = true;
1821 : 0 : goto exit;
1822 : : }
1823 : :
1824 : : /* first time, allocate or get the custom wait event */
1825 [ + + ]: 95 : if (pgfdw_we_cleanup_result == 0)
1826 : 2 : pgfdw_we_cleanup_result = WaitEventExtensionNew("PostgresFdwCleanupResult");
1827 : :
1828 : : /* Sleep until there's something to do */
1829 : 95 : wc = WaitLatchOrSocket(MyLatch,
1830 : : WL_LATCH_SET | WL_SOCKET_READABLE |
1831 : : WL_TIMEOUT | WL_EXIT_ON_PM_DEATH,
1832 : : PQsocket(conn),
1833 : : cur_timeout, pgfdw_we_cleanup_result);
1834 : 95 : ResetLatch(MyLatch);
1835 : :
1836 [ - + ]: 95 : CHECK_FOR_INTERRUPTS();
1837 : :
1838 : : /* Data available in socket? */
1839 [ + - ]: 95 : if (wc & WL_SOCKET_READABLE)
1840 : : {
1841 [ + + ]: 95 : if (!PQconsumeInput(conn))
1842 : : {
1843 : : /* connection trouble */
1844 : 3 : failed = true;
1845 : 3 : goto exit;
1846 : : }
1847 : : }
1848 : : }
1849 : :
1850 : 213 : res = PQgetResult(conn);
1851 [ + + ]: 213 : if (res == NULL)
1852 : 99 : break; /* query is complete */
1853 : :
1854 : 114 : PQclear(last_res);
1855 : 114 : last_res = res;
1856 : : }
1857 : 102 : exit:
1858 [ + + ]: 102 : if (failed)
1859 : 3 : PQclear(last_res);
1860 : : else
1861 : 99 : *result = last_res;
1862 : 102 : return failed;
1863 : : }
1864 : :
1865 : : /*
1866 : : * Abort remote transaction or subtransaction.
1867 : : *
1868 : : * "toplevel" should be set to true if toplevel (main) transaction is
1869 : : * rollbacked, false otherwise.
1870 : : *
1871 : : * Set entry->changing_xact_state to false on success, true on failure.
1872 : : */
1873 : : static void
1874 : 66 : pgfdw_abort_cleanup(ConnCacheEntry *entry, bool toplevel)
1875 : : {
1876 : : char sql[100];
1877 : :
1878 : : /*
1879 : : * Don't try to clean up the connection if we're already in error
1880 : : * recursion trouble.
1881 : : */
1882 [ - + ]: 66 : if (in_error_recursion_trouble())
1883 : 0 : entry->changing_xact_state = true;
1884 : :
1885 : : /*
1886 : : * If connection is already unsalvageable, don't touch it further.
1887 : : */
1888 [ + + ]: 66 : if (entry->changing_xact_state)
1889 : 6 : return;
1890 : :
1891 : : /*
1892 : : * Mark this connection as in the process of changing transaction state.
1893 : : */
1894 : 63 : entry->changing_xact_state = true;
1895 : :
1896 : : /* Assume we might have lost track of prepared statements */
1897 : 63 : entry->have_error = true;
1898 : :
1899 : : /*
1900 : : * If a command has been submitted to the remote server by using an
1901 : : * asynchronous execution function, the command might not have yet
1902 : : * completed. Check to see if a command is still being processed by the
1903 : : * remote server, and if so, request cancellation of the command.
1904 : : */
1905 [ + + ]: 63 : if (PQtransactionStatus(entry->conn) == PQTRANS_ACTIVE &&
1906 [ - + ]: 2 : !pgfdw_cancel_query(entry->conn))
1907 : 0 : return; /* Unable to cancel running query */
1908 : :
1909 [ + + ]: 63 : CONSTRUCT_ABORT_COMMAND(sql, entry, toplevel);
1910 [ + + ]: 63 : if (!pgfdw_exec_cleanup_query(entry->conn, sql, false))
1911 : 3 : return; /* Unable to abort remote (sub)transaction */
1912 : :
1913 [ + + ]: 60 : if (toplevel)
1914 : : {
1915 [ + + + - ]: 52 : if (entry->have_prep_stmt && entry->have_error &&
1916 [ - + ]: 25 : !pgfdw_exec_cleanup_query(entry->conn,
1917 : : "DEALLOCATE ALL",
1918 : : true))
1919 : 0 : return; /* Trouble clearing prepared statements */
1920 : :
1921 : 52 : entry->have_prep_stmt = false;
1922 : 52 : entry->have_error = false;
1923 : : }
1924 : :
1925 : : /*
1926 : : * If pendingAreq of the per-connection state is not NULL, it means that
1927 : : * an asynchronous fetch begun by fetch_more_data_begin() was not done
1928 : : * successfully and thus the per-connection state was not reset in
1929 : : * fetch_more_data(); in that case reset the per-connection state here.
1930 : : */
1931 [ + + ]: 60 : if (entry->state.pendingAreq)
1932 : 1 : memset(&entry->state, 0, sizeof(entry->state));
1933 : :
1934 : : /* Disarm changing_xact_state if it all worked */
1935 : 60 : entry->changing_xact_state = false;
1936 : : }
1937 : :
1938 : : /*
1939 : : * Like pgfdw_abort_cleanup, submit an abort command or cancel request, but
1940 : : * don't wait for the result.
1941 : : *
1942 : : * Returns true if the abort command or cancel request is successfully issued,
1943 : : * false otherwise. If the abort command is successfully issued, the given
1944 : : * connection cache entry is appended to *pending_entries. Otherwise, if the
1945 : : * cancel request is successfully issued, it is appended to *cancel_requested.
1946 : : */
1947 : : static bool
1948 : 8 : pgfdw_abort_cleanup_begin(ConnCacheEntry *entry, bool toplevel,
1949 : : List **pending_entries, List **cancel_requested)
1950 : : {
1951 : : /*
1952 : : * Don't try to clean up the connection if we're already in error
1953 : : * recursion trouble.
1954 : : */
1955 [ - + ]: 8 : if (in_error_recursion_trouble())
1956 : 0 : entry->changing_xact_state = true;
1957 : :
1958 : : /*
1959 : : * If connection is already unsalvageable, don't touch it further.
1960 : : */
1961 [ - + ]: 8 : if (entry->changing_xact_state)
1962 : 0 : return false;
1963 : :
1964 : : /*
1965 : : * Mark this connection as in the process of changing transaction state.
1966 : : */
1967 : 8 : entry->changing_xact_state = true;
1968 : :
1969 : : /* Assume we might have lost track of prepared statements */
1970 : 8 : entry->have_error = true;
1971 : :
1972 : : /*
1973 : : * If a command has been submitted to the remote server by using an
1974 : : * asynchronous execution function, the command might not have yet
1975 : : * completed. Check to see if a command is still being processed by the
1976 : : * remote server, and if so, request cancellation of the command.
1977 : : */
1978 [ - + ]: 8 : if (PQtransactionStatus(entry->conn) == PQTRANS_ACTIVE)
1979 : : {
1980 : : TimestampTz endtime;
1981 : :
1982 : 0 : endtime = TimestampTzPlusMilliseconds(GetCurrentTimestamp(),
1983 : : CONNECTION_CLEANUP_TIMEOUT);
1984 [ # # ]: 0 : if (!pgfdw_cancel_query_begin(entry->conn, endtime))
1985 : 0 : return false; /* Unable to cancel running query */
1986 : 0 : *cancel_requested = lappend(*cancel_requested, entry);
1987 : : }
1988 : : else
1989 : : {
1990 : : char sql[100];
1991 : :
1992 [ + + ]: 8 : CONSTRUCT_ABORT_COMMAND(sql, entry, toplevel);
1993 [ - + ]: 8 : if (!pgfdw_exec_cleanup_query_begin(entry->conn, sql))
1994 : 0 : return false; /* Unable to abort remote transaction */
1995 : 8 : *pending_entries = lappend(*pending_entries, entry);
1996 : : }
1997 : :
1998 : 8 : return true;
1999 : : }
2000 : :
2001 : : /*
2002 : : * Finish pre-commit cleanup of connections on each of which we've sent a
2003 : : * COMMIT command to the remote server.
2004 : : */
2005 : : static void
2006 : 13 : pgfdw_finish_pre_commit_cleanup(List *pending_entries)
2007 : : {
2008 : : ConnCacheEntry *entry;
2009 : 13 : List *pending_deallocs = NIL;
2010 : : ListCell *lc;
2011 : :
2012 : : Assert(pending_entries);
2013 : :
2014 : : /*
2015 : : * Get the result of the COMMIT command for each of the pending entries
2016 : : */
2017 [ + - + + : 29 : foreach(lc, pending_entries)
+ + ]
2018 : : {
2019 : 16 : entry = (ConnCacheEntry *) lfirst(lc);
2020 : :
2021 : : Assert(entry->changing_xact_state);
2022 : :
2023 : : /*
2024 : : * We might already have received the result on the socket, so pass
2025 : : * consume_input=true to try to consume it first
2026 : : */
2027 : 16 : do_sql_command_end(entry->conn, "COMMIT TRANSACTION", true);
2028 : 16 : entry->changing_xact_state = false;
2029 : :
2030 : : /* Do a DEALLOCATE ALL in parallel if needed */
2031 [ + + + + ]: 16 : if (entry->have_prep_stmt && entry->have_error)
2032 : : {
2033 : : /* Ignore errors (see notes in pgfdw_xact_callback) */
2034 [ + - ]: 2 : if (PQsendQuery(entry->conn, "DEALLOCATE ALL"))
2035 : : {
2036 : 2 : pending_deallocs = lappend(pending_deallocs, entry);
2037 : 2 : continue;
2038 : : }
2039 : : }
2040 : 14 : entry->have_prep_stmt = false;
2041 : 14 : entry->have_error = false;
2042 : :
2043 : 14 : pgfdw_reset_xact_state(entry, true);
2044 : : }
2045 : :
2046 : : /* No further work if no pending entries */
2047 [ + + ]: 13 : if (!pending_deallocs)
2048 : 12 : return;
2049 : :
2050 : : /*
2051 : : * Get the result of the DEALLOCATE command for each of the pending
2052 : : * entries
2053 : : */
2054 [ + - + + : 3 : foreach(lc, pending_deallocs)
+ + ]
2055 : : {
2056 : : PGresult *res;
2057 : :
2058 : 2 : entry = (ConnCacheEntry *) lfirst(lc);
2059 : :
2060 : : /* Ignore errors (see notes in pgfdw_xact_callback) */
2061 [ + + ]: 4 : while ((res = PQgetResult(entry->conn)) != NULL)
2062 : : {
2063 : 2 : PQclear(res);
2064 : : /* Stop if the connection is lost (else we'll loop infinitely) */
2065 [ - + ]: 2 : if (PQstatus(entry->conn) == CONNECTION_BAD)
2066 : 0 : break;
2067 : : }
2068 : 2 : entry->have_prep_stmt = false;
2069 : 2 : entry->have_error = false;
2070 : :
2071 : 2 : pgfdw_reset_xact_state(entry, true);
2072 : : }
2073 : : }
2074 : :
2075 : : /*
2076 : : * Finish pre-subcommit cleanup of connections on each of which we've sent a
2077 : : * RELEASE command to the remote server.
2078 : : */
2079 : : static void
2080 : 1 : pgfdw_finish_pre_subcommit_cleanup(List *pending_entries, int curlevel)
2081 : : {
2082 : : ConnCacheEntry *entry;
2083 : : char sql[100];
2084 : : ListCell *lc;
2085 : :
2086 : : Assert(pending_entries);
2087 : :
2088 : : /*
2089 : : * Get the result of the RELEASE command for each of the pending entries
2090 : : */
2091 : 1 : snprintf(sql, sizeof(sql), "RELEASE SAVEPOINT s%d", curlevel);
2092 [ + - + + : 3 : foreach(lc, pending_entries)
+ + ]
2093 : : {
2094 : 2 : entry = (ConnCacheEntry *) lfirst(lc);
2095 : :
2096 : : Assert(entry->changing_xact_state);
2097 : :
2098 : : /*
2099 : : * We might already have received the result on the socket, so pass
2100 : : * consume_input=true to try to consume it first
2101 : : */
2102 : 2 : do_sql_command_end(entry->conn, sql, true);
2103 : 2 : entry->changing_xact_state = false;
2104 : :
2105 : 2 : pgfdw_reset_xact_state(entry, false);
2106 : : }
2107 : 1 : }
2108 : :
2109 : : /*
2110 : : * Finish abort cleanup of connections on each of which we've sent an abort
2111 : : * command or cancel request to the remote server.
2112 : : */
2113 : : static void
2114 : 4 : pgfdw_finish_abort_cleanup(List *pending_entries, List *cancel_requested,
2115 : : bool toplevel)
2116 : : {
2117 : 4 : List *pending_deallocs = NIL;
2118 : : ListCell *lc;
2119 : :
2120 : : /*
2121 : : * For each of the pending cancel requests (if any), get and discard the
2122 : : * result of the query, and submit an abort command to the remote server.
2123 : : */
2124 [ - + ]: 4 : if (cancel_requested)
2125 : : {
2126 [ # # # # : 0 : foreach(lc, cancel_requested)
# # ]
2127 : : {
2128 : 0 : ConnCacheEntry *entry = (ConnCacheEntry *) lfirst(lc);
2129 : 0 : TimestampTz now = GetCurrentTimestamp();
2130 : : TimestampTz endtime;
2131 : : TimestampTz retrycanceltime;
2132 : : char sql[100];
2133 : :
2134 : : Assert(entry->changing_xact_state);
2135 : :
2136 : : /*
2137 : : * Set end time. You might think we should do this before issuing
2138 : : * cancel request like in normal mode, but that is problematic,
2139 : : * because if, for example, it took longer than 30 seconds to
2140 : : * process the first few entries in the cancel_requested list, it
2141 : : * would cause a timeout error when processing each of the
2142 : : * remaining entries in the list, leading to slamming that entry's
2143 : : * connection shut.
2144 : : */
2145 : 0 : endtime = TimestampTzPlusMilliseconds(now,
2146 : : CONNECTION_CLEANUP_TIMEOUT);
2147 : 0 : retrycanceltime = TimestampTzPlusMilliseconds(now,
2148 : : RETRY_CANCEL_TIMEOUT);
2149 : :
2150 [ # # ]: 0 : if (!pgfdw_cancel_query_end(entry->conn, endtime,
2151 : : retrycanceltime, true))
2152 : : {
2153 : : /* Unable to cancel running query */
2154 : 0 : pgfdw_reset_xact_state(entry, toplevel);
2155 : 0 : continue;
2156 : : }
2157 : :
2158 : : /* Send an abort command in parallel if needed */
2159 [ # # ]: 0 : CONSTRUCT_ABORT_COMMAND(sql, entry, toplevel);
2160 [ # # ]: 0 : if (!pgfdw_exec_cleanup_query_begin(entry->conn, sql))
2161 : : {
2162 : : /* Unable to abort remote (sub)transaction */
2163 : 0 : pgfdw_reset_xact_state(entry, toplevel);
2164 : : }
2165 : : else
2166 : 0 : pending_entries = lappend(pending_entries, entry);
2167 : : }
2168 : : }
2169 : :
2170 : : /* No further work if no pending entries */
2171 [ - + ]: 4 : if (!pending_entries)
2172 : 0 : return;
2173 : :
2174 : : /*
2175 : : * Get the result of the abort command for each of the pending entries
2176 : : */
2177 [ + - + + : 12 : foreach(lc, pending_entries)
+ + ]
2178 : : {
2179 : 8 : ConnCacheEntry *entry = (ConnCacheEntry *) lfirst(lc);
2180 : : TimestampTz endtime;
2181 : : char sql[100];
2182 : :
2183 : : Assert(entry->changing_xact_state);
2184 : :
2185 : : /*
2186 : : * Set end time. We do this now, not before issuing the command like
2187 : : * in normal mode, for the same reason as for the cancel_requested
2188 : : * entries.
2189 : : */
2190 : 8 : endtime = TimestampTzPlusMilliseconds(GetCurrentTimestamp(),
2191 : : CONNECTION_CLEANUP_TIMEOUT);
2192 : :
2193 [ + + ]: 8 : CONSTRUCT_ABORT_COMMAND(sql, entry, toplevel);
2194 [ - + ]: 8 : if (!pgfdw_exec_cleanup_query_end(entry->conn, sql, endtime,
2195 : : true, false))
2196 : : {
2197 : : /* Unable to abort remote (sub)transaction */
2198 : 0 : pgfdw_reset_xact_state(entry, toplevel);
2199 : 4 : continue;
2200 : : }
2201 : :
2202 [ + + ]: 8 : if (toplevel)
2203 : : {
2204 : : /* Do a DEALLOCATE ALL in parallel if needed */
2205 [ + - + - ]: 4 : if (entry->have_prep_stmt && entry->have_error)
2206 : : {
2207 [ - + ]: 4 : if (!pgfdw_exec_cleanup_query_begin(entry->conn,
2208 : : "DEALLOCATE ALL"))
2209 : : {
2210 : : /* Trouble clearing prepared statements */
2211 : 0 : pgfdw_reset_xact_state(entry, toplevel);
2212 : : }
2213 : : else
2214 : 4 : pending_deallocs = lappend(pending_deallocs, entry);
2215 : 4 : continue;
2216 : : }
2217 : 0 : entry->have_prep_stmt = false;
2218 : 0 : entry->have_error = false;
2219 : : }
2220 : :
2221 : : /* Reset the per-connection state if needed */
2222 [ - + ]: 4 : if (entry->state.pendingAreq)
2223 : 0 : memset(&entry->state, 0, sizeof(entry->state));
2224 : :
2225 : : /* We're done with this entry; unset the changing_xact_state flag */
2226 : 4 : entry->changing_xact_state = false;
2227 : 4 : pgfdw_reset_xact_state(entry, toplevel);
2228 : : }
2229 : :
2230 : : /* No further work if no pending entries */
2231 [ + + ]: 4 : if (!pending_deallocs)
2232 : 2 : return;
2233 : : Assert(toplevel);
2234 : :
2235 : : /*
2236 : : * Get the result of the DEALLOCATE command for each of the pending
2237 : : * entries
2238 : : */
2239 [ + - + + : 6 : foreach(lc, pending_deallocs)
+ + ]
2240 : : {
2241 : 4 : ConnCacheEntry *entry = (ConnCacheEntry *) lfirst(lc);
2242 : : TimestampTz endtime;
2243 : :
2244 : : Assert(entry->changing_xact_state);
2245 : : Assert(entry->have_prep_stmt);
2246 : : Assert(entry->have_error);
2247 : :
2248 : : /*
2249 : : * Set end time. We do this now, not before issuing the command like
2250 : : * in normal mode, for the same reason as for the cancel_requested
2251 : : * entries.
2252 : : */
2253 : 4 : endtime = TimestampTzPlusMilliseconds(GetCurrentTimestamp(),
2254 : : CONNECTION_CLEANUP_TIMEOUT);
2255 : :
2256 [ - + ]: 4 : if (!pgfdw_exec_cleanup_query_end(entry->conn, "DEALLOCATE ALL",
2257 : : endtime, true, true))
2258 : : {
2259 : : /* Trouble clearing prepared statements */
2260 : 0 : pgfdw_reset_xact_state(entry, toplevel);
2261 : 0 : continue;
2262 : : }
2263 : 4 : entry->have_prep_stmt = false;
2264 : 4 : entry->have_error = false;
2265 : :
2266 : : /* Reset the per-connection state if needed */
2267 [ - + ]: 4 : if (entry->state.pendingAreq)
2268 : 0 : memset(&entry->state, 0, sizeof(entry->state));
2269 : :
2270 : : /* We're done with this entry; unset the changing_xact_state flag */
2271 : 4 : entry->changing_xact_state = false;
2272 : 4 : pgfdw_reset_xact_state(entry, toplevel);
2273 : : }
2274 : : }
2275 : :
2276 : : /* Number of output arguments (columns) for various API versions */
2277 : : #define POSTGRES_FDW_GET_CONNECTIONS_COLS_V1_1 2
2278 : : #define POSTGRES_FDW_GET_CONNECTIONS_COLS_V1_2 6
2279 : : #define POSTGRES_FDW_GET_CONNECTIONS_COLS 6 /* maximum of above */
2280 : :
2281 : : /*
2282 : : * Internal function used by postgres_fdw_get_connections variants.
2283 : : *
2284 : : * For API version 1.1, this function takes no input parameter and
2285 : : * returns a set of records with the following values:
2286 : : *
2287 : : * - server_name - server name of active connection. In case the foreign server
2288 : : * is dropped but still the connection is active, then the server name will
2289 : : * be NULL in output.
2290 : : * - valid - true/false representing whether the connection is valid or not.
2291 : : * Note that connections can become invalid in pgfdw_inval_callback.
2292 : : *
2293 : : * For API version 1.2 and later, this function takes an input parameter
2294 : : * to check a connection status and returns the following
2295 : : * additional values along with the four values from version 1.1:
2296 : : *
2297 : : * - user_name - the local user name of the active connection. In case the
2298 : : * user mapping is dropped but the connection is still active, then the
2299 : : * user name will be NULL in the output.
2300 : : * - used_in_xact - true if the connection is used in the current transaction.
2301 : : * - closed - true if the connection is closed.
2302 : : * - remote_backend_pid - process ID of the remote backend, on the foreign
2303 : : * server, handling the connection.
2304 : : *
2305 : : * No records are returned when there are no cached connections at all.
2306 : : */
2307 : : static void
2308 : 14 : postgres_fdw_get_connections_internal(FunctionCallInfo fcinfo,
2309 : : enum pgfdwVersion api_version)
2310 : : {
2311 : 14 : ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
2312 : : HASH_SEQ_STATUS scan;
2313 : : ConnCacheEntry *entry;
2314 : :
2315 : 14 : InitMaterializedSRF(fcinfo, 0);
2316 : :
2317 : : /* If cache doesn't exist, we return no records */
2318 [ - + ]: 14 : if (!ConnectionHash)
2319 : 0 : return;
2320 : :
2321 : : /* Check we have the expected number of output arguments */
2322 [ - + - ]: 14 : switch (rsinfo->setDesc->natts)
2323 : : {
2324 : 0 : case POSTGRES_FDW_GET_CONNECTIONS_COLS_V1_1:
2325 [ # # ]: 0 : if (api_version != PGFDW_V1_1)
2326 [ # # ]: 0 : elog(ERROR, "incorrect number of output arguments");
2327 : 0 : break;
2328 : 14 : case POSTGRES_FDW_GET_CONNECTIONS_COLS_V1_2:
2329 [ - + ]: 14 : if (api_version != PGFDW_V1_2)
2330 [ # # ]: 0 : elog(ERROR, "incorrect number of output arguments");
2331 : 14 : break;
2332 : 0 : default:
2333 [ # # ]: 0 : elog(ERROR, "incorrect number of output arguments");
2334 : : }
2335 : :
2336 : 14 : hash_seq_init(&scan, ConnectionHash);
2337 [ + + ]: 123 : while ((entry = (ConnCacheEntry *) hash_seq_search(&scan)))
2338 : : {
2339 : : ForeignServer *server;
2340 : 109 : Datum values[POSTGRES_FDW_GET_CONNECTIONS_COLS] = {0};
2341 : 109 : bool nulls[POSTGRES_FDW_GET_CONNECTIONS_COLS] = {0};
2342 : 109 : int i = 0;
2343 : :
2344 : : /* We only look for open remote connections */
2345 [ + + ]: 109 : if (!entry->conn)
2346 : 95 : continue;
2347 : :
2348 : 14 : server = GetForeignServerExtended(entry->serverid, FSV_MISSING_OK);
2349 : :
2350 : : /*
2351 : : * The foreign server may have been dropped in current explicit
2352 : : * transaction. It is not possible to drop the server from another
2353 : : * session when the connection associated with it is in use in the
2354 : : * current transaction, if tried so, the drop query in another session
2355 : : * blocks until the current transaction finishes.
2356 : : *
2357 : : * Even though the server is dropped in the current transaction, the
2358 : : * cache can still have associated active connection entry, say we
2359 : : * call such connections dangling. Since we can not fetch the server
2360 : : * name from system catalogs for dangling connections, instead we show
2361 : : * NULL value for server name in output.
2362 : : *
2363 : : * We could have done better by storing the server name in the cache
2364 : : * entry instead of server oid so that it could be used in the output.
2365 : : * But the server name in each cache entry requires 64 bytes of
2366 : : * memory, which is huge, when there are many cached connections and
2367 : : * the use case i.e. dropping the foreign server within the explicit
2368 : : * current transaction seems rare. So, we chose to show NULL value for
2369 : : * server name in output.
2370 : : *
2371 : : * Such dangling connections get closed either in next use or at the
2372 : : * end of current explicit transaction in pgfdw_xact_callback.
2373 : : */
2374 [ + + ]: 14 : if (!server)
2375 : : {
2376 : : /*
2377 : : * If the server has been dropped in the current explicit
2378 : : * transaction, then this entry would have been invalidated in
2379 : : * pgfdw_inval_callback at the end of drop server command. Note
2380 : : * that this connection would not have been closed in
2381 : : * pgfdw_inval_callback because it is still being used in the
2382 : : * current explicit transaction. So, assert that here.
2383 : : */
2384 : : Assert(entry->conn && entry->xact_depth > 0 && entry->invalidated);
2385 : :
2386 : : /* Show null, if no server name was found */
2387 : 1 : nulls[i++] = true;
2388 : : }
2389 : : else
2390 : 13 : values[i++] = CStringGetTextDatum(server->servername);
2391 : :
2392 [ + - ]: 14 : if (api_version >= PGFDW_V1_2)
2393 : : {
2394 : : HeapTuple tp;
2395 : :
2396 : : /* Use the system cache to obtain the user mapping */
2397 : 14 : tp = SearchSysCache1(USERMAPPINGOID, ObjectIdGetDatum(entry->key));
2398 : :
2399 : : /*
2400 : : * Just like in the foreign server case, user mappings can also be
2401 : : * dropped in the current explicit transaction. Therefore, the
2402 : : * similar check as in the server case is required.
2403 : : */
2404 [ + + ]: 14 : if (!HeapTupleIsValid(tp))
2405 : : {
2406 : : /*
2407 : : * If we reach here, this entry must have been invalidated in
2408 : : * pgfdw_inval_callback, same as in the server case.
2409 : : */
2410 : : Assert(entry->conn && entry->xact_depth > 0 &&
2411 : : entry->invalidated);
2412 : :
2413 : 1 : nulls[i++] = true;
2414 : : }
2415 : : else
2416 : : {
2417 : : Oid userid;
2418 : :
2419 : 13 : userid = ((Form_pg_user_mapping) GETSTRUCT(tp))->umuser;
2420 [ + + ]: 13 : values[i++] = CStringGetTextDatum(MappingUserName(userid));
2421 : 13 : ReleaseSysCache(tp);
2422 : : }
2423 : : }
2424 : :
2425 : 14 : values[i++] = BoolGetDatum(!entry->invalidated);
2426 : :
2427 [ + - ]: 14 : if (api_version >= PGFDW_V1_2)
2428 : : {
2429 : 14 : bool check_conn = PG_GETARG_BOOL(0);
2430 : :
2431 : : /* Is this connection used in the current transaction? */
2432 : 14 : values[i++] = BoolGetDatum(entry->xact_depth > 0);
2433 : :
2434 : : /*
2435 : : * If a connection status check is requested and supported, return
2436 : : * whether the connection is closed. Otherwise, return NULL.
2437 : : */
2438 [ + + + - ]: 14 : if (check_conn && pgfdw_conn_checkable())
2439 : 3 : values[i++] = BoolGetDatum(pgfdw_conn_check(entry->conn) != 0);
2440 : : else
2441 : 11 : nulls[i++] = true;
2442 : :
2443 : : /* Return process ID of remote backend */
2444 : 14 : values[i++] = Int32GetDatum(PQbackendPID(entry->conn));
2445 : : }
2446 : :
2447 : 14 : tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
2448 : : }
2449 : : }
2450 : :
2451 : : /*
2452 : : * Values in connection strings must be enclosed in single quotes. Single
2453 : : * quotes and backslashes must be escaped with backslash. NB: these rules are
2454 : : * different from the rules for escaping a SQL literal.
2455 : : */
2456 : : static void
2457 : 79 : appendEscapedValue(StringInfo str, const char *val)
2458 : : {
2459 : 79 : appendStringInfoChar(str, '\'');
2460 [ + + ]: 674 : for (int i = 0; val[i] != '\0'; i++)
2461 : : {
2462 [ + - - + ]: 595 : if (val[i] == '\\' || val[i] == '\'')
2463 : 0 : appendStringInfoChar(str, '\\');
2464 : 595 : appendStringInfoChar(str, val[i]);
2465 : : }
2466 : 79 : appendStringInfoChar(str, '\'');
2467 : 79 : }
2468 : :
2469 : : Datum
2470 : 11 : postgres_fdw_connection(PG_FUNCTION_ARGS)
2471 : : {
2472 : 11 : Oid userid = PG_GETARG_OID(0);
2473 : 11 : Oid serverid = PG_GETARG_OID(1);
2474 : 11 : ForeignServer *server = GetForeignServer(serverid);
2475 : 11 : UserMapping *user = GetUserMapping(userid, serverid);
2476 : : StringInfoData str;
2477 : : const char **keywords;
2478 : : const char **values;
2479 : : char *appname;
2480 : 11 : char *sep = "";
2481 : :
2482 : 11 : construct_connection_params(server, user, &keywords, &values, &appname);
2483 : :
2484 : 11 : initStringInfo(&str);
2485 [ + + ]: 90 : for (int i = 0; keywords[i] != NULL; i++)
2486 : : {
2487 [ - + ]: 79 : if (values[i] == NULL)
2488 : 0 : continue;
2489 : 79 : appendStringInfo(&str, "%s%s = ", sep, keywords[i]);
2490 : 79 : appendEscapedValue(&str, values[i]);
2491 : 79 : sep = " ";
2492 : : }
2493 : :
2494 [ + + ]: 11 : if (appname != NULL)
2495 : 1 : pfree(appname);
2496 : 11 : pfree(keywords);
2497 : 11 : pfree(values);
2498 : 11 : PG_RETURN_TEXT_P(cstring_to_text(str.data));
2499 : : }
2500 : :
2501 : : /*
2502 : : * List active foreign server connections.
2503 : : *
2504 : : * The SQL API of this function has changed multiple times, and will likely
2505 : : * do so again in future. To support the case where a newer version of this
2506 : : * loadable module is being used with an old SQL declaration of the function,
2507 : : * we continue to support the older API versions.
2508 : : */
2509 : : Datum
2510 : 14 : postgres_fdw_get_connections_1_2(PG_FUNCTION_ARGS)
2511 : : {
2512 : 14 : postgres_fdw_get_connections_internal(fcinfo, PGFDW_V1_2);
2513 : :
2514 : 14 : PG_RETURN_VOID();
2515 : : }
2516 : :
2517 : : Datum
2518 : 0 : postgres_fdw_get_connections(PG_FUNCTION_ARGS)
2519 : : {
2520 : 0 : postgres_fdw_get_connections_internal(fcinfo, PGFDW_V1_1);
2521 : :
2522 : 0 : PG_RETURN_VOID();
2523 : : }
2524 : :
2525 : : /*
2526 : : * Disconnect the specified cached connections.
2527 : : *
2528 : : * This function discards the open connections that are established by
2529 : : * postgres_fdw from the local session to the foreign server with
2530 : : * the given name. Note that there can be multiple connections to
2531 : : * the given server using different user mappings. If the connections
2532 : : * are used in the current local transaction, they are not disconnected
2533 : : * and warning messages are reported. This function returns true
2534 : : * if it disconnects at least one connection, otherwise false. If no
2535 : : * foreign server with the given name is found, an error is reported.
2536 : : */
2537 : : Datum
2538 : 4 : postgres_fdw_disconnect(PG_FUNCTION_ARGS)
2539 : : {
2540 : : ForeignServer *server;
2541 : : char *servername;
2542 : :
2543 : 4 : servername = text_to_cstring(PG_GETARG_TEXT_PP(0));
2544 : 4 : server = GetForeignServerByName(servername, false);
2545 : :
2546 : 3 : PG_RETURN_BOOL(disconnect_cached_connections(server->serverid));
2547 : : }
2548 : :
2549 : : /*
2550 : : * Disconnect all the cached connections.
2551 : : *
2552 : : * This function discards all the open connections that are established by
2553 : : * postgres_fdw from the local session to the foreign servers.
2554 : : * If the connections are used in the current local transaction, they are
2555 : : * not disconnected and warning messages are reported. This function
2556 : : * returns true if it disconnects at least one connection, otherwise false.
2557 : : */
2558 : : Datum
2559 : 6 : postgres_fdw_disconnect_all(PG_FUNCTION_ARGS)
2560 : : {
2561 : 6 : PG_RETURN_BOOL(disconnect_cached_connections(InvalidOid));
2562 : : }
2563 : :
2564 : : /*
2565 : : * Workhorse to disconnect cached connections.
2566 : : *
2567 : : * This function scans all the connection cache entries and disconnects
2568 : : * the open connections whose foreign server OID matches with
2569 : : * the specified one. If InvalidOid is specified, it disconnects all
2570 : : * the cached connections.
2571 : : *
2572 : : * This function emits a warning for each connection that's used in
2573 : : * the current transaction and doesn't close it. It returns true if
2574 : : * it disconnects at least one connection, otherwise false.
2575 : : *
2576 : : * Note that this function disconnects even the connections that are
2577 : : * established by other users in the same local session using different
2578 : : * user mappings. This leads even non-superuser to be able to close
2579 : : * the connections established by superusers in the same local session.
2580 : : *
2581 : : * XXX As of now we don't see any security risk doing this. But we should
2582 : : * set some restrictions on that, for example, prevent non-superuser
2583 : : * from closing the connections established by superusers even
2584 : : * in the same session?
2585 : : */
2586 : : static bool
2587 : 9 : disconnect_cached_connections(Oid serverid)
2588 : : {
2589 : : HASH_SEQ_STATUS scan;
2590 : : ConnCacheEntry *entry;
2591 : 9 : bool all = !OidIsValid(serverid);
2592 : 9 : bool result = false;
2593 : :
2594 : : /*
2595 : : * Connection cache hashtable has not been initialized yet in this
2596 : : * session, so return false.
2597 : : */
2598 [ - + ]: 9 : if (!ConnectionHash)
2599 : 0 : return false;
2600 : :
2601 : 9 : hash_seq_init(&scan, ConnectionHash);
2602 [ + + ]: 77 : while ((entry = (ConnCacheEntry *) hash_seq_search(&scan)))
2603 : : {
2604 : : /* Ignore cache entry if no open connection right now. */
2605 [ + + ]: 68 : if (!entry->conn)
2606 : 55 : continue;
2607 : :
2608 [ + + + + ]: 13 : if (all || entry->serverid == serverid)
2609 : : {
2610 : : /*
2611 : : * Emit a warning because the connection to close is used in the
2612 : : * current transaction and cannot be disconnected right now.
2613 : : */
2614 [ + + ]: 10 : if (entry->xact_depth > 0)
2615 : : {
2616 : : ForeignServer *server;
2617 : :
2618 : 3 : server = GetForeignServerExtended(entry->serverid,
2619 : : FSV_MISSING_OK);
2620 : :
2621 [ - + ]: 3 : if (!server)
2622 : : {
2623 : : /*
2624 : : * If the foreign server was dropped while its connection
2625 : : * was used in the current transaction, the connection
2626 : : * must have been marked as invalid by
2627 : : * pgfdw_inval_callback at the end of DROP SERVER command.
2628 : : */
2629 : : Assert(entry->invalidated);
2630 : :
2631 [ # # ]: 0 : ereport(WARNING,
2632 : : (errmsg("cannot close dropped server connection because it is still in use")));
2633 : : }
2634 : : else
2635 [ + - ]: 3 : ereport(WARNING,
2636 : : (errmsg("cannot close connection for server \"%s\" because it is still in use",
2637 : : server->servername)));
2638 : : }
2639 : : else
2640 : : {
2641 [ - + ]: 7 : elog(DEBUG3, "discarding connection %p", entry->conn);
2642 : 7 : disconnect_pg_server(entry);
2643 : 7 : result = true;
2644 : : }
2645 : : }
2646 : : }
2647 : :
2648 : 9 : return result;
2649 : : }
2650 : :
2651 : : /*
2652 : : * Check if the remote server closed the connection.
2653 : : *
2654 : : * Returns 1 if the connection is closed, -1 if an error occurred,
2655 : : * and 0 if it's not closed or if the connection check is unavailable
2656 : : * on this platform.
2657 : : */
2658 : : static int
2659 : 3 : pgfdw_conn_check(PGconn *conn)
2660 : : {
2661 : 3 : int sock = PQsocket(conn);
2662 : :
2663 [ + - - + ]: 3 : if (PQstatus(conn) != CONNECTION_OK || sock == -1)
2664 : 0 : return -1;
2665 : :
2666 : : #if (defined(HAVE_POLL) && defined(POLLRDHUP))
2667 : : {
2668 : : struct pollfd input_fd;
2669 : : int result;
2670 : :
2671 : 3 : input_fd.fd = sock;
2672 : 3 : input_fd.events = POLLRDHUP;
2673 : 3 : input_fd.revents = 0;
2674 : :
2675 : : do
2676 : 3 : result = poll(&input_fd, 1, 0);
2677 [ - + - - ]: 3 : while (result < 0 && errno == EINTR);
2678 : :
2679 [ - + ]: 3 : if (result < 0)
2680 : 0 : return -1;
2681 : :
2682 : 3 : return (input_fd.revents &
2683 : 3 : (POLLRDHUP | POLLHUP | POLLERR | POLLNVAL)) ? 1 : 0;
2684 : : }
2685 : : #else
2686 : : return 0;
2687 : : #endif
2688 : : }
2689 : :
2690 : : /*
2691 : : * Check if connection status checking is available on this platform.
2692 : : *
2693 : : * Returns true if available, false otherwise.
2694 : : */
2695 : : static bool
2696 : 3 : pgfdw_conn_checkable(void)
2697 : : {
2698 : : #if (defined(HAVE_POLL) && defined(POLLRDHUP))
2699 : 3 : return true;
2700 : : #else
2701 : : return false;
2702 : : #endif
2703 : : }
2704 : :
2705 : : /*
2706 : : * Ensure that require_auth and SCRAM keys are correctly set on values. SCRAM
2707 : : * keys used to pass-through are coming from the initial connection from the
2708 : : * client with the server.
2709 : : *
2710 : : * All required SCRAM options are set by postgres_fdw, so we just need to
2711 : : * ensure that these options are not overwritten by the user.
2712 : : */
2713 : : static bool
2714 : 9 : pgfdw_has_required_scram_options(const char **keywords, const char **values)
2715 : : {
2716 : 9 : bool has_scram_server_key = false;
2717 : 9 : bool has_scram_client_key = false;
2718 : 9 : bool has_require_auth = false;
2719 : 9 : bool has_scram_keys = false;
2720 : :
2721 : : /*
2722 : : * Continue iterating even if we found the keys that we need to validate
2723 : : * to make sure that there is no other declaration of these keys that can
2724 : : * overwrite the first.
2725 : : */
2726 [ + + ]: 87 : for (int i = 0; keywords[i] != NULL; i++)
2727 : : {
2728 [ + + ]: 78 : if (strcmp(keywords[i], "scram_client_key") == 0)
2729 : : {
2730 [ + - + - ]: 8 : if (values[i] != NULL && values[i][0] != '\0')
2731 : 8 : has_scram_client_key = true;
2732 : : else
2733 : 0 : has_scram_client_key = false;
2734 : : }
2735 : :
2736 [ + + ]: 78 : if (strcmp(keywords[i], "scram_server_key") == 0)
2737 : : {
2738 [ + - + - ]: 8 : if (values[i] != NULL && values[i][0] != '\0')
2739 : 8 : has_scram_server_key = true;
2740 : : else
2741 : 0 : has_scram_server_key = false;
2742 : : }
2743 : :
2744 [ + + ]: 78 : if (strcmp(keywords[i], "require_auth") == 0)
2745 : : {
2746 [ + - + - ]: 8 : if (values[i] != NULL && strcmp(values[i], "scram-sha-256") == 0)
2747 : 8 : has_require_auth = true;
2748 : : else
2749 : 0 : has_require_auth = false;
2750 : : }
2751 : : }
2752 : :
2753 [ + + + - : 9 : has_scram_keys = has_scram_client_key && has_scram_server_key && MyProcPort != NULL && MyProcPort->has_scram_keys;
+ - + - ]
2754 : :
2755 [ + + + - ]: 9 : return (has_scram_keys && has_require_auth);
2756 : : }
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