db_http: fix crash when loading module along with tls_mgm

(cherry picked from commit f925153)

modules/db_http/Makefile

@@ -26,4 +26,6 @@ else
 	LIBS =-L$(LOCALBASE)/lib -lcurl
 endif 
 
+LIBS += -dl -Bsymbolic
+
 include ../../Makefile.modules

modules/db_http/db_http.c

@@ -26,11 +26,13 @@
 
 
 
+#define _GNU_SOURCE
+
 #include "../../sr_module.h"
 #include "../../db/db.h"
 #include "http_dbase.h"
-
-
+#include "../../ssl_init_tweaks.h"
+#include "../../pt.h"
 
 
 static int http_mod_init(void);

modules/db_http/ssl_tweaks.c

@@ -0,0 +1,49 @@
+/*
+ * Copyright (C) 2021 OpenSIPS Project
+ *
+ * This file is part of opensips, a free SIP server.
+ *
+ * opensips is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * opensips is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ */
+
+#define _GNU_SOURCE
+
+#include <openssl/ssl.h>
+#include <dlfcn.h>
+
+#include "../../sr_module.h"
+#include "../../globals.h"
+
+/* don't call the real openssl function (from libssh's destructor) when the
+ * pre-daemon processes exit */
+void BN_clear_free(BIGNUM *a)
+{
+	void (*real_BN_clear_free)(BIGNUM *a);
+	static int have_tls_mgm = -1;
+
+	if (have_tls_mgm == -1)
+		have_tls_mgm = module_loaded("tls_mgm");
+
+	if (have_tls_mgm && !no_daemon_mode && is_pre_daemon) {
+		return;
+	} else {
+		real_BN_clear_free = dlsym(RTLD_NEXT, "BN_clear_free");
+		if (!real_BN_clear_free)
+			return;
+
+		real_BN_clear_free(a);
+	}
+}