Remove support for OpenSSL 0.9.8 and 1.0.0

Support is out of scope from all the major vendors for these versions
(for example RHEL5 uses a version based on 0.9.8, and RHEL6 uses 1.0.1),
and it created some extra maintenance work.  Upstream has stopped
support of 0.9.8 in December 2015 and of 1.0.0 in February 2016.

Since b1abfec8, note that the default SSL protocol version set with
ssl_min_protocol_version is TLSv1.2, whose support was added in OpenSSL
1.0.1, so there is no point to enforce ssl_min_protocol_version to TLSv1
in the SSL tests.

Author: Michael Paquier
Reviewed-by: Daniel Gustafsson, Tom Lane
Discussion: https://postgr.es/m/20191205083252.GE5064@paquier.xyz

doc/src/sgml/installation.sgml

@@ -254,7 +254,7 @@ su - postgres
       encrypted client connections.  <productname>OpenSSL</productname> is
       also required for random number generation on platforms that do not
       have <filename>/dev/urandom</filename> (except Windows).  The minimum
-      version required is 0.9.8.
+      version required is 1.0.1.
      </para>
     </listitem>
 

doc/src/sgml/libpq.sgml

@@ -1608,10 +1608,6 @@ postgresql://%2Fvar%2Flib%2Fpostgresql/dbname
         compression by default, and many operating system distributions
         disable it in prior versions as well, so setting this parameter to on
         will not have any effect if the server does not accept compression.
-        On the other hand, <productname>OpenSSL</productname> before 1.0.0
-        does not support disabling compression, so this parameter is ignored
-        with those versions, and whether compression is used depends on the
-        server.
        </para>
 
        <para>

src/backend/libpq/be-secure-openssl.c

@@ -223,9 +223,7 @@ be_tls_init(bool isServerStart)
 	}
 
 	/* disallow SSL session tickets */
-#ifdef SSL_OP_NO_TICKET			/* added in OpenSSL 0.9.8f */
 	SSL_CTX_set_options(context, SSL_OP_NO_TICKET);
-#endif
 
 	/* disallow SSL session caching, too */
 	SSL_CTX_set_session_cache_mode(context, SSL_SESS_CACHE_OFF);

src/interfaces/libpq/fe-secure-openssl.c

@@ -1192,15 +1192,12 @@ initialize_SSL(PGconn *conn)
 		SSL_set_verify(conn->ssl, SSL_VERIFY_PEER, verify_cb);
 
 	/*
-	 * Set compression option if the OpenSSL version used supports it (from
-	 * 1.0.0 on).
+	 * Set compression option if necessary.
 	 */
-#ifdef SSL_OP_NO_COMPRESSION
 	if (conn->sslcompression && conn->sslcompression[0] == '0')
 		SSL_set_options(conn->ssl, SSL_OP_NO_COMPRESSION);
 	else
 		SSL_clear_options(conn->ssl, SSL_OP_NO_COMPRESSION);
-#endif
 
 	return 0;
 }

src/test/ssl/t/SSLServer.pm

@@ -132,10 +132,6 @@ sub configure_test_server_for_ssl
 	print $conf "listen_addresses='$serverhost'\n";
 	print $conf "log_statement=all\n";
 
-	# Accept even old TLS versions so that builds with older OpenSSL
-	# can run the test suite.
-	print $conf "ssl_min_protocol_version='TLSv1'\n";
-
 	# enable SSL and set up server key
 	print $conf "include 'sslconfig.conf'\n";