Change the error message for logical replication authentication failure.

The authentication failure error message wasn't distinguishing whether
it is a physical replication or logical replication connection failure and
was giving incomplete information on what led to failure in case of logical
replication connection.

Author: Paul Martinez and Amit Kapila
Reviewed-by: Euler Taveira and Amit Kapila
Discussion: https://postgr.es/m/CACqFVBYahrAi2OPdJfUA3YCvn3QMzzxZdw0ibSJ8wouWeDtiyQ@mail.gmail.com

doc/src/sgml/client-auth.sgml

@@ -229,8 +229,10 @@ hostnogssenc  <replaceable>database</replaceable>  <replaceable>user</replaceabl
        members of the role, directly or indirectly, and not just by
        virtue of being a superuser.
        The value <literal>replication</literal> specifies that the record
-       matches if a physical replication connection is requested (note that
-       replication connections do not specify any particular database).
+       matches if a physical replication connection is requested, however, it
+       doesn't match with logical replication connections. Note that physical
+       replication connections do not specify any particular database whereas
+       logical replication connections do specify it.
        Otherwise, this is the name of
        a specific <productname>PostgreSQL</productname> database.
        Multiple database names can be supplied by separating them with

src/backend/libpq/auth.c

@@ -417,7 +417,7 @@ ClientAuthentication(Port *port)
 #endif
 					_("no encryption");
 
-				if (am_walsender)
+				if (am_walsender && !am_db_walsender)
 					ereport(FATAL,
 							(errcode(ERRCODE_INVALID_AUTHORIZATION_SPECIFICATION),
 					/* translator: last %s describes encryption state */
@@ -484,7 +484,7 @@ ClientAuthentication(Port *port)
 								  gai_strerror(port->remote_hostname_errcode)) : \
 					0))
 
-				if (am_walsender)
+				if (am_walsender && !am_db_walsender)
 					ereport(FATAL,
 							(errcode(ERRCODE_INVALID_AUTHORIZATION_SPECIFICATION),
 					/* translator: last %s describes encryption state */