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Fix bogus behavior of PQsslAttribute(conn, "library"). 

Commit ebc8b7d44 intended to change the behavior of
PQsslAttribute(NULL, "library"), but accidentally also changed
what happens with a non-NULL conn pointer.  Undo that so that
only the intended behavior change happens.  Clarify some
associated documentation.

Per bug #17625 from Heath Lord.  Back-patch to v15.

Discussion: https://postgr.es/m/17625-fc47c78b7d71b534@postgresql.org
This commit is contained in:
Tom Lane 2022-09-29 17:28:09 -04:00
parent 551aa6b7b9
commit 80a05679d5
2 changed files with 32 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

36
doc/src/sgml/libpq.sgml
View File

@ -2514,8 +2514,9 @@ const char *PQsslAttribute(const PGconn *conn, const char *attribute_name);
<para>
The list of available attributes varies depending on the SSL library
being used, and the type of connection. If an attribute is not
available, returns NULL.
being used and the type of connection. Returns NULL if the connection
does not use SSL or the specified attribute name is not defined for the
library in use.
</para>
<para>
@ -2574,12 +2575,15 @@ const char *PQsslAttribute(const PGconn *conn, const char *attribute_name);
<para>
As a special case, the <literal>library</literal> attribute may be
queried without an existing connection by passing NULL as the
<literal>conn</literal> argument. The historical behavior was to return
NULL for any attribute when a NULL <literal>conn</literal> was provided;
client programs needing to differentiate between the newer and older
implementations may check the
<literal>LIBPQ_HAS_SSL_LIBRARY_DETECTION</literal> feature macro.
queried without a connection by passing NULL as
the <literal>conn</literal> argument. The result will be the default
SSL library name, or NULL if <application>libpq</application> was
compiled without any SSL support. (Prior
to <productname>PostgreSQL</productname> version 15, passing NULL as
the <literal>conn</literal> argument always resulted in NULL.
Client programs needing to differentiate between the newer and older
implementations of this case may check the
<literal>LIBPQ_HAS_SSL_LIBRARY_DETECTION</literal> feature macro.)
</para>
</listitem>
</varlistentry>
@ -2588,7 +2592,8 @@ const char *PQsslAttribute(const PGconn *conn, const char *attribute_name);
<term><function>PQsslAttributeNames</function><indexterm><primary>PQsslAttributeNames</primary></indexterm></term>
<listitem>
<para>
Return an array of SSL attribute names available. The array is terminated by a NULL pointer.
Returns an array of SSL attribute names available.
The array is terminated by a NULL pointer.
<synopsis>
const char * const * PQsslAttributeNames(const PGconn *conn);
</synopsis>
@ -2600,8 +2605,10 @@ const char * const * PQsslAttributeNames(const PGconn *conn);
<term><function>PQsslStruct</function><indexterm><primary>PQsslStruct</primary></indexterm></term>
<listitem>
<para>
Return a pointer to an SSL-implementation-specific object describing
the connection.
Returns a pointer to an SSL-implementation-specific object describing
the connection. Returns NULL if the connection is not encrypted
or the requested type of object is not available from the connection's
SSL implementation.
<synopsis>
void *PQsslStruct(const PGconn *conn, const char *struct_name);
</synopsis>
@ -2609,8 +2616,9 @@ void *PQsslStruct(const PGconn *conn, const char *struct_name);
<para>
The struct(s) available depend on the SSL implementation in use.
For <productname>OpenSSL</productname>, there is one struct,
available under the name "OpenSSL", and it returns a pointer to the
<productname>OpenSSL</productname> <literal>SSL</literal> struct.
available under the name <literal>OpenSSL</literal>,
and it returns a pointer to
<productname>OpenSSL</productname>'s <literal>SSL</literal> struct.
To use this function, code along the following lines could be used:
<programlisting><![CDATA[
#include <libpq-fe.h>
@ -2643,7 +2651,7 @@ void *PQsslStruct(const PGconn *conn, const char *struct_name);
<listitem>
<para>
<indexterm><primary>SSL</primary><secondary sortas="libpq">in libpq</secondary></indexterm>
Returns the SSL structure used in the connection, or null
Returns the SSL structure used in the connection, or NULL
if SSL is not in use.
<synopsis>

13
src/interfaces/libpq/fe-secure-openssl.c
View File

@ -1745,14 +1745,21 @@ PQsslAttributeNames(PGconn *conn)
const char *
PQsslAttribute(PGconn *conn, const char *attribute_name)
{
if (strcmp(attribute_name, "library") == 0)
return "OpenSSL";
if (!conn)
{
/* PQsslAttribute(NULL, "library") reports the default SSL library */
if (strcmp(attribute_name, "library") == 0)
return "OpenSSL";
return NULL;
}
/* All attributes read as NULL for a non-encrypted connection */
if (conn->ssl == NULL)
return NULL;
if (strcmp(attribute_name, "library") == 0)
return "OpenSSL";
if (strcmp(attribute_name, "key_bits") == 0)
{
static char sslbits_str[12];