src/fe_utils/connect_utils.c

   1 /*-------------------------------------------------------------------------
   2  *
   3  * Facilities for frontend code to connect to and disconnect from databases.
   4  *
   5  * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
   6  * Portions Copyright (c) 1994, Regents of the University of California
   7  *
   8  * src/fe_utils/connect_utils.c
   9  *
  10  *-------------------------------------------------------------------------
  11  */
  12 #include "postgres_fe.h"
  13
  14 #include "common/connect.h"
  15 #include "common/logging.h"
  16 #include "common/string.h"
  17 #include "fe_utils/connect_utils.h"
  18 #include "fe_utils/query_utils.h"
  19
  20 /*
  21  * Make a database connection with the given parameters.
  22  *
  23  * An interactive password prompt is automatically issued if needed and
  24  * allowed by cparams->prompt_password.
  25  *
  26  * If allow_password_reuse is true, we will try to re-use any password
  27  * given during previous calls to this routine.  (Callers should not pass
  28  * allow_password_reuse=true unless reconnecting to the same host+port+user
  29  * as before, else we might create password exposure hazards.)
  30  */
  31 PGconn *
  32 connectDatabase(const ConnParams *cparams, const char *progname,
  33                                 bool echo, bool fail_ok, bool allow_password_reuse)
  34 {
  35         PGconn     *conn;
  36         bool            new_pass;
  37         static char *password = NULL;
  38
  39         /* Callers must supply at least dbname; other params can be NULL */
  40         Assert(cparams->dbname);
  41
  42         if (!allow_password_reuse && password)
  43         {
  44                 free(password);
  45                 password = NULL;
  46         }
  47
  48         if (cparams->prompt_password == TRI_YES && password == NULL)
  49                 password = simple_prompt("Password: ", false);
  50
  51         /*
  52          * Start the connection.  Loop until we have a password if requested by
  53          * backend.
  54          */
  55         do
  56         {
  57                 const char *keywords[8];
  58                 const char *values[8];
  59                 int                     i = 0;
  60
  61                 /*
  62                  * If dbname is a connstring, its entries can override the other
  63                  * values obtained from cparams; but in turn, override_dbname can
  64                  * override the dbname component of it.
  65                  */
  66                 keywords[i] = "host";
  67                 values[i++] = cparams->pghost;
  68                 keywords[i] = "port";
  69                 values[i++] = cparams->pgport;
  70                 keywords[i] = "user";
  71                 values[i++] = cparams->pguser;
  72                 keywords[i] = "password";
  73                 values[i++] = password;
  74                 keywords[i] = "dbname";
  75                 values[i++] = cparams->dbname;
  76                 if (cparams->override_dbname)
  77                 {
  78                         keywords[i] = "dbname";
  79                         values[i++] = cparams->override_dbname;
  80                 }
  81                 keywords[i] = "fallback_application_name";
  82                 values[i++] = progname;
  83                 keywords[i] = NULL;
  84                 values[i++] = NULL;
  85                 Assert(i <= lengthof(keywords));
  86
  87                 new_pass = false;
  88                 conn = PQconnectdbParams(keywords, values, true);
  89
  90                 if (!conn)
  91                         pg_fatal("could not connect to database %s: out of memory",
  92                                          cparams->dbname);
  93
  94                 /*
  95                  * No luck?  Trying asking (again) for a password.
  96                  */
  97                 if (PQstatus(conn) == CONNECTION_BAD &&
  98                         PQconnectionNeedsPassword(conn) &&
  99                         cparams->prompt_password != TRI_NO)
 100                 {
 101                         PQfinish(conn);
 102                         free(password);
 103                         password = simple_prompt("Password: ", false);
 104                         new_pass = true;
 105                 }
 106         } while (new_pass);
 107
 108         /* check to see that the backend connection was successfully made */
 109         if (PQstatus(conn) == CONNECTION_BAD)
 110         {
 111                 if (fail_ok)
 112                 {
 113                         PQfinish(conn);
 114                         return NULL;
 115                 }
 116                 pg_fatal("%s", PQerrorMessage(conn));
 117         }
 118
 119         /* Start strict; callers may override this. */
 120         PQclear(executeQuery(conn, ALWAYS_SECURE_SEARCH_PATH_SQL, echo));
 121
 122         return conn;
 123 }
 124
 125 /*
 126  * Try to connect to the appropriate maintenance database.
 127  *
 128  * This differs from connectDatabase only in that it has a rule for
 129  * inserting a default "dbname" if none was given (which is why cparams
 130  * is not const).  Note that cparams->dbname should typically come from
 131  * a --maintenance-db command line parameter.
 132  */
 133 PGconn *
 134 connectMaintenanceDatabase(ConnParams *cparams,
 135                                                    const char *progname, bool echo)
 136 {
 137         PGconn     *conn;
 138
 139         /* If a maintenance database name was specified, just connect to it. */
 140         if (cparams->dbname)
 141                 return connectDatabase(cparams, progname, echo, false, false);
 142
 143         /* Otherwise, try postgres first and then template1. */
 144         cparams->dbname = "postgres";
 145         conn = connectDatabase(cparams, progname, echo, true, false);
 146         if (!conn)
 147         {
 148                 cparams->dbname = "template1";
 149                 conn = connectDatabase(cparams, progname, echo, false, false);
 150         }
 151         return conn;
 152 }
 153
 154 /*
 155  * Disconnect the given connection, canceling any statement if one is active.
 156  */
 157 void
 158 disconnectDatabase(PGconn *conn)
 159 {
 160         Assert(conn != NULL);
 161
 162         if (PQtransactionStatus(conn) == PQTRANS_ACTIVE)
 163         {
 164                 PGcancelConn *cancelConn = PQcancelCreate(conn);
 165
 166                 (void) PQcancelBlocking(cancelConn);
 167                 PQcancelFinish(cancelConn);
 168         }
 169
 170         PQfinish(conn);
 171 }