Add support for OpenSSL, mbedTLS 2 and mbedTLS 3

Brings the previous OpenSSL implementation into src/IO/tls_openssl.c.

Now, the TLS functions have the implementation name as prefix, like
a_Tls_openssl_connect().

The generic interface at IO/tls.h hides the implementation which is
selected at configure time. The appropriate functions of that
implementation are called from IO/tls.c to IO/tls_<impl>.c. In this way,
support for more TLS libraries can easily be added.

In the case of mbedTLS, there are some incompatible changes from version
2 to 3, so we use some ifdefs to fix the differences.

1 files changed, 50 insertions, 0 deletions

diff --git a/src/IO/tls.h b/src/IO/tls.h
new file mode 100644
index 00000000..25da6ea6
--- /dev/null
+++ b/src/IO/tls.h
@@ -0,0 +1,50 @@
+/*
+ * File: tls.h
+ *
+ * Copyright (C) 2011 Benjamin Johnson <obeythepenguin@users.sourceforge.net>
+ * (for the https code offered from dplus browser that formed the basis...)
+ * Copyright 2016 corvid
+ * Copyright (C) 2023 Rodrigo Arias Mallo <rodarima@gmail.com>
+ *
+ * This program 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 3 of the License, or
+ * (at your option) any later version.
+ *
+ * As a special exception, permission is granted to link Dillo with the OpenSSL
+ * or LibreSSL library, and distribute the linked executables without
+ * including the source code for OpenSSL or LibreSSL in the source
+ * distribution. You must obey the GNU General Public License, version 3, in
+ * all respects for all of the code used other than OpenSSL or LibreSSL.
+ */
+
+#ifndef __TLS_H__
+#define __TLS_H__
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include "../url.h"
+
+#define TLS_CONNECT_NEVER -1
+#define TLS_CONNECT_NOT_YET 0
+#define TLS_CONNECT_READY 1
+
+void a_Tls_init();
+int a_Tls_certificate_is_clean(const DilloUrl *url);
+int a_Tls_connect_ready(const DilloUrl *url);
+void a_Tls_reset_server_state(const DilloUrl *url);
+void a_Tls_connect(int fd, const DilloUrl *url);
+void *a_Tls_connection(int fd);
+void a_Tls_freeall();
+void a_Tls_close_by_fd(int fd);
+int a_Tls_read(void *conn, void *buf, size_t len);
+int a_Tls_write(void *conn, void *buf, size_t len);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* __TLS_H__ */
+