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Allow full SSL certificate verification (wherein libpq checks its host name
parameter against server cert's CN field) to succeed in the case where both host and hostaddr are specified. As with the existing precedents for Kerberos, GSSAPI, SSPI, it is the calling application's responsibility that host and hostaddr match up --- we just use the host name as given. Per bug #5559 from Christopher Head. In passing, make the error handling and messages for the no-host-name-given failure more consistent among these four cases, and correct a lie in the documentation: we don't attempt to reverse-lookup host from hostaddr if host is missing. Back-patch to 8.4 where SSL cert verification was introduced.
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-33
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4 files changed

+38
-33
lines changed

‎doc/src/sgml/libpq.sgml

Lines changed: 21 additions & 17 deletions
Original file line numberDiff line numberDiff line change
@@ -1,4 +1,4 @@
1-
<!-- $PostgreSQL: pgsql/doc/src/sgml/libpq.sgml,v 1.313 2010/07/08 10:20:14 mha Exp $ -->
1+
<!-- $PostgreSQL: pgsql/doc/src/sgml/libpq.sgml,v 1.314 2010/07/14 17:09:45 tgl Exp $ -->
22

33
<chapter id="libpq">
44
<title><application>libpq</application> - C Library</title>
@@ -162,22 +162,26 @@
162162

163163
<para>
164164
Using <literal>hostaddr</> instead of <literal>host</> allows the
165-
application to avoid a host name look-up, which might be important in
166-
applications with time constraints. However, Kerberos and GSSAPI authentication
167-
requires the host name. The following therefore applies: If
168-
<literal>host</> is specified without <literal>hostaddr</>, a host name
169-
lookup occurs. If <literal>hostaddr</> is specified without
170-
<literal>host</>, the value for <literal>hostaddr</> gives the remote
171-
address. When Kerberos is used, a reverse name query occurs to obtain
172-
the host name for Kerberos. If both
173-
<literal>host</> and <literal>hostaddr</> are specified, the value for
174-
<literal>hostaddr</> gives the remote address; the value for
175-
<literal>host</> is ignored, unless Kerberos is used, in which case that
176-
value is used for Kerberos authentication. (Note that authentication is
177-
likely to fail if <application>libpq</application> is passed a host name
178-
that is not the name of the machine at <literal>hostaddr</>.) Also,
179-
<literal>host</> rather than <literal>hostaddr</> is used to identify
180-
the connection in <filename>~/.pgpass</> (see
165+
application to avoid a host name look-up, which might be important
166+
in applications with time constraints. However, a host name is
167+
required for Kerberos, GSSAPI, or SSPI authentication, as well as
168+
for full SSL certificate verification. The following rules are
169+
used:
170+
If <literal>host</> is specified without <literal>hostaddr</>,
171+
a host name lookup occurs.
172+
If <literal>hostaddr</> is specified without <literal>host</>,
173+
the value for <literal>hostaddr</> gives the server address.
174+
The connection attempt will fail in any of the cases where a
175+
host name is required.
176+
If both <literal>host</> and <literal>hostaddr</> are specified,
177+
the value for <literal>hostaddr</> gives the server address.
178+
The value for <literal>host</> is ignored unless needed for
179+
authentication or verification purposes, in which case it will be
180+
used as the host name. Note that authentication is likely to fail
181+
if <literal>host</> is not the name of the machine at
182+
<literal>hostaddr</>.
183+
Also, note that <literal>host</> rather than <literal>hostaddr</>
184+
is used to identify the connection in <filename>~/.pgpass</> (see
181185
<xref linkend="libpq-pgpass">).
182186
</para>
183187

‎src/interfaces/libpq/fe-auth.c

Lines changed: 9 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
* Portions Copyright (c) 1994, Regents of the University of California
88
*
99
* IDENTIFICATION
10-
* $PostgreSQL: pgsql/src/interfaces/libpq/fe-auth.c,v 1.144 2010/03/08 10:01:12 mha Exp $
10+
* $PostgreSQL: pgsql/src/interfaces/libpq/fe-auth.c,v 1.145 2010/07/14 17:09:45 tgl Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -206,10 +206,10 @@ pg_krb5_sendauth(PGconn *conn)
206206

207207
info.pg_krb5_initialised = 0;
208208

209-
if (!conn->pghost)
209+
if (!(conn->pghost && conn->pghost[0] != '\0'))
210210
{
211211
printfPQExpBuffer(&conn->errorMessage,
212-
"pg_krb5_sendauth: hostname must be specified for Kerberos authentication\n");
212+
libpq_gettext("host name must be specified\n"));
213213
return STATUS_ERROR;
214214
}
215215

@@ -426,9 +426,10 @@ pg_GSS_startup(PGconn *conn)
426426
int maxlen;
427427
gss_buffer_desc temp_gbuf;
428428

429-
if (!conn->pghost)
429+
if (!(conn->pghost && conn->pghost[0] != '\0'))
430430
{
431-
printfPQExpBuffer(&conn->errorMessage, libpq_gettext("host name must be specified\n"));
431+
printfPQExpBuffer(&conn->errorMessage,
432+
libpq_gettext("host name must be specified\n"));
432433
return STATUS_ERROR;
433434
}
434435

@@ -652,9 +653,10 @@ pg_SSPI_startup(PGconn *conn, int use_negotiate)
652653
* but not more complex. We can skip the @REALM part, because Windows will
653654
* fill that in for us automatically.
654655
*/
655-
if (conn->pghost == NULL)
656+
if (!(conn->pghost && conn->pghost[0] != '\0'))
656657
{
657-
printfPQExpBuffer(&conn->errorMessage, libpq_gettext("host name must be specified\n"));
658+
printfPQExpBuffer(&conn->errorMessage,
659+
libpq_gettext("host name must be specified\n"));
658660
return STATUS_ERROR;
659661
}
660662
conn->sspitarget = malloc(strlen(conn->krbsrvname) + strlen(conn->pghost) + 2);

‎src/interfaces/libpq/fe-secure.c

Lines changed: 4 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -11,7 +11,7 @@
1111
*
1212
*
1313
* IDENTIFICATION
14-
* $PostgreSQL: pgsql/src/interfaces/libpq/fe-secure.c,v 1.135 2010/07/06 19:19:01 momjian Exp $
14+
* $PostgreSQL: pgsql/src/interfaces/libpq/fe-secure.c,v 1.136 2010/07/14 17:09:45 tgl Exp $
1515
*
1616
* NOTES
1717
*
@@ -589,16 +589,16 @@ static bool
589589
verify_peer_name_matches_certificate(PGconn *conn)
590590
{
591591
/*
592-
* If told not to verify the peer name, don't do it. Return 0 indicating
592+
* If told not to verify the peer name, don't do it. Return true indicating
593593
* that the verification was successful.
594594
*/
595595
if (strcmp(conn->sslmode, "verify-full") != 0)
596596
return true;
597597

598-
if (conn->pghostaddr)
598+
if (!(conn->pghost && conn->pghost[0] != '\0'))
599599
{
600600
printfPQExpBuffer(&conn->errorMessage,
601-
libpq_gettext("verified SSL connections are only supported when connecting to a host name\n"));
601+
libpq_gettext("host name must be specified for a verified SSL connection\n"));
602602
return false;
603603
}
604604
else

‎src/interfaces/libpq/libpq-int.h

Lines changed: 4 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -12,7 +12,7 @@
1212
* Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
1313
* Portions Copyright (c) 1994, Regents of the University of California
1414
*
15-
* $PostgreSQL: pgsql/src/interfaces/libpq/libpq-int.h,v 1.152 2010/07/06 19:19:01 momjian Exp $
15+
* $PostgreSQL: pgsql/src/interfaces/libpq/libpq-int.h,v 1.153 2010/07/14 17:09:45 tgl Exp $
1616
*
1717
*-------------------------------------------------------------------------
1818
*/
@@ -282,10 +282,9 @@ struct pg_conn
282282
{
283283
/* Saved values of connection options */
284284
char *pghost; /* the machine on which the server is running */
285-
char *pghostaddr; /* the IPv4 address of the machine on which
286-
* the server is running, in IPv4
287-
* numbers-and-dots notation. Takes precedence
288-
* over above. */
285+
char *pghostaddr; /* the numeric IP address of the machine on
286+
* which the server is running. Takes
287+
* precedence over above. */
289288
char *pgport; /* the server's communication port */
290289
char *pgunixsocket; /* the Unix-domain socket that the server is
291290
* listening on; if NULL, uses a default

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