From 80a05679d5a400b8f995740c175f8bdb060bb05c Mon Sep 17 00:00:00 2001
From: Tom Lane
Date: Thu, 29 Sep 2022 17:28:09 -0400
Subject: 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
---
 src/interfaces/libpq/fe-secure-openssl.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

(limited to 'src/interfaces/libpq/fe-secure-openssl.c')

diff --git a/src/interfaces/libpq/fe-secure-openssl.c b/src/interfaces/libpq/fe-secure-openssl.c
index aea4661736c..74b5c5987a6 100644
--- a/src/interfaces/libpq/fe-secure-openssl.c
+++ b/src/interfaces/libpq/fe-secure-openssl.c
@@ -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];
-- 
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