1 /*-------------------------------------------------------------------------
2 *
3 * Facilities for frontend code to connect to and disconnect from databases.
4 *
5 * Portions Copyright (c) 1996-2021, 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 database+user
29 * as before, else we might create password exposure hazards.)
30 */
31 PGconn *
connectDatabase(const ConnParams * cparams,const char * progname,bool echo,bool fail_ok,bool allow_password_reuse)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 {
92 pg_log_error("could not connect to database %s: out of memory",
93 cparams->dbname);
94 exit(1);
95 }
96
97 /*
98 * No luck? Trying asking (again) for a password.
99 */
100 if (PQstatus(conn) == CONNECTION_BAD &&
101 PQconnectionNeedsPassword(conn) &&
102 cparams->prompt_password != TRI_NO)
103 {
104 PQfinish(conn);
105 if (password)
106 free(password);
107 password = simple_prompt("Password: ", false);
108 new_pass = true;
109 }
110 } while (new_pass);
111
112 /* check to see that the backend connection was successfully made */
113 if (PQstatus(conn) == CONNECTION_BAD)
114 {
115 if (fail_ok)
116 {
117 PQfinish(conn);
118 return NULL;
119 }
120 pg_log_error("%s", PQerrorMessage(conn));
121 exit(1);
122 }
123
124 /* Start strict; callers may override this. */
125 PQclear(executeQuery(conn, ALWAYS_SECURE_SEARCH_PATH_SQL, echo));
126
127 return conn;
128 }
129
130 /*
131 * Try to connect to the appropriate maintenance database.
132 *
133 * This differs from connectDatabase only in that it has a rule for
134 * inserting a default "dbname" if none was given (which is why cparams
135 * is not const). Note that cparams->dbname should typically come from
136 * a --maintenance-db command line parameter.
137 */
138 PGconn *
connectMaintenanceDatabase(ConnParams * cparams,const char * progname,bool echo)139 connectMaintenanceDatabase(ConnParams *cparams,
140 const char *progname, bool echo)
141 {
142 PGconn *conn;
143
144 /* If a maintenance database name was specified, just connect to it. */
145 if (cparams->dbname)
146 return connectDatabase(cparams, progname, echo, false, false);
147
148 /* Otherwise, try postgres first and then template1. */
149 cparams->dbname = "postgres";
150 conn = connectDatabase(cparams, progname, echo, true, false);
151 if (!conn)
152 {
153 cparams->dbname = "template1";
154 conn = connectDatabase(cparams, progname, echo, false, false);
155 }
156 return conn;
157 }
158
159 /*
160 * Disconnect the given connection, canceling any statement if one is active.
161 */
162 void
disconnectDatabase(PGconn * conn)163 disconnectDatabase(PGconn *conn)
164 {
165 char errbuf[256];
166
167 Assert(conn != NULL);
168
169 if (PQtransactionStatus(conn) == PQTRANS_ACTIVE)
170 {
171 PGcancel *cancel;
172
173 if ((cancel = PQgetCancel(conn)))
174 {
175 (void) PQcancel(cancel, errbuf, sizeof(errbuf));
176 PQfreeCancel(cancel);
177 }
178 }
179
180 PQfinish(conn);
181 }
182