Enable SSL library detection via PQsslAttribute()

Currently, libpq client code must have a connection handle
before it can query the "library" SSL attribute.  This poses
problems if the client needs to know what SSL library is in
use before constructing a connection string.

Allow PQsslAttribute(NULL, "library") to return the library
in use -- currently, just "OpenSSL" or NULL. The new behavior
is announced with the LIBPQ_HAS_SSL_LIBRARY_DETECTION feature
macro, allowing clients to differentiate between a libpq that
was compiled without SSL support and a libpq that's just too
old to tell.

Author: Jacob Champion <[email protected]>
Reviewed-by: Robert Haas <[email protected]>
Reviewed-by: Daniel Gustafsson <[email protected]>
Discussion: https://postgr.es/m/[email protected]

1 files changed, 3 insertions, 3 deletions

diff --git a/src/interfaces/libpq/fe-secure-openssl.c b/src/interfaces/libpq/fe-secure-openssl.c
index d81218a4ccd..d3bf57b850a 100644
--- a/src/interfaces/libpq/fe-secure-openssl.c
+++ b/src/interfaces/libpq/fe-secure-openssl.c
@@ -1631,14 +1631,14 @@ PQsslAttributeNames(PGconn *conn)
 const char *
 PQsslAttribute(PGconn *conn, const char *attribute_name)
 {
+	if (strcmp(attribute_name, "library") == 0)
+		return "OpenSSL";
+
 	if (!conn)
 		return NULL;
 	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];