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, 175 insertions, 0 deletions

diff --git a/src/IO/tls.c b/src/IO/tls.c
new file mode 100644
index 00000000..2a27c1a6
--- /dev/null
+++ b/src/IO/tls.c
@@ -0,0 +1,175 @@
+/*
+ * File: tls.c
+ *
+ * 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.
+ */
+
+#include "config.h"
+#include "../msg.h"
+
+#include "tls.h"
+#include "tls_openssl.h"
+#include "tls_mbedtls.h"
+
+void a_Tls_init()
+{
+#if ! defined(ENABLE_TLS)
+   MSG("TLS: Disabled at compilation time.\n");
+#elif defined(HAVE_OPENSSL)
+   a_Tls_openssl_init();
+#elif defined(HAVE_MBEDTLS)
+   a_Tls_mbedtls_init();
+#else
+# error "no TLS library found but ENABLE_TLS set"
+#endif
+}
+
+/*
+ * Return TLS connection information for a given file
+ * descriptor, or NULL if no TLS connection was found.
+ */
+void *a_Tls_connection(int fd)
+{
+#if ! defined(ENABLE_TLS)
+   return NULL;
+#elif defined(HAVE_OPENSSL)
+   return a_Tls_openssl_connection(fd);
+#elif defined(HAVE_MBEDTLS)
+   return a_Tls_mbedtls_connection(fd);
+#else
+# error "no TLS library found but ENABLE_TLS set"
+#endif
+}
+
+/*
+ * The purpose here is to permit a single initial connection to a server.
+ * Once we have the certificate, know whether we like it -- and whether the
+ * user accepts it -- HTTP can run through queued sockets as normal.
+ *
+ * Return: TLS_CONNECT_READY or TLS_CONNECT_NOT_YET or TLS_CONNECT_NEVER.
+ */
+int a_Tls_connect_ready(const DilloUrl *url)
+{
+#if ! defined(ENABLE_TLS)
+   return TLS_CONNECT_NEVER;
+#elif defined(HAVE_OPENSSL)
+   return a_Tls_openssl_connect_ready(url);
+#elif defined(HAVE_MBEDTLS)
+   return a_Tls_mbedtls_connect_ready(url);
+#else
+# error "no TLS library found but ENABLE_TLS set"
+#endif
+}
+
+/*
+ * Did everything seem proper with the certificate -- no warnings to
+ * click through?
+ */
+int a_Tls_certificate_is_clean(const DilloUrl *url)
+{
+#if ! defined(ENABLE_TLS)
+   return 0;
+#elif defined(HAVE_OPENSSL)
+   return a_Tls_openssl_certificate_is_clean(url);
+#elif defined(HAVE_MBEDTLS)
+   return a_Tls_mbedtls_certificate_is_clean(url);
+#else
+# error "no TLS library found but ENABLE_TLS set"
+#endif
+}
+
+/*
+ * Clean up the OpenSSL library
+ */
+void a_Tls_freeall(void)
+{
+#if ! defined(ENABLE_TLS)
+   return;
+#elif defined(HAVE_OPENSSL)
+   a_Tls_openssl_freeall();
+#elif defined(HAVE_MBEDTLS)
+   a_Tls_mbedtls_freeall();
+#else
+# error "no TLS library found but ENABLE_TLS set"
+#endif
+}
+
+
+void a_Tls_reset_server_state(const DilloUrl *url)
+{
+#if ! defined(ENABLE_TLS)
+   return;
+#elif defined(HAVE_OPENSSL)
+   a_Tls_openssl_reset_server_state(url);
+#elif defined(HAVE_MBEDTLS)
+   a_Tls_mbedtls_reset_server_state(url);
+#else
+# error "no TLS library found but ENABLE_TLS set"
+#endif
+}
+
+void a_Tls_connect(int fd, const DilloUrl *url)
+{
+#if ! defined(ENABLE_TLS)
+   return;
+#elif defined(HAVE_OPENSSL)
+   a_Tls_openssl_connect(fd, url);
+#elif defined(HAVE_MBEDTLS)
+   a_Tls_mbedtls_connect(fd, url);
+#else
+# error "no TLS library found but ENABLE_TLS set"
+#endif
+}
+
+void a_Tls_close_by_fd(int fd)
+{
+#if ! defined(ENABLE_TLS)
+   return;
+#elif defined(HAVE_OPENSSL)
+   a_Tls_openssl_close_by_fd(fd);
+#elif defined(HAVE_MBEDTLS)
+   a_Tls_mbedtls_close_by_fd(fd);
+#else
+# error "no TLS library found but ENABLE_TLS set"
+#endif
+}
+
+int a_Tls_read(void *conn, void *buf, size_t len)
+{
+#if ! defined(ENABLE_TLS)
+   return 0;
+#elif defined(HAVE_OPENSSL)
+   return a_Tls_openssl_read(conn, buf, len);
+#elif defined(HAVE_MBEDTLS)
+   return a_Tls_mbedtls_read(conn, buf, len);
+#else
+# error "no TLS library found but ENABLE_TLS set"
+#endif
+}
+
+int a_Tls_write(void *conn, void *buf, size_t len)
+{
+#if ! defined(ENABLE_TLS)
+   return 0;
+#elif defined(HAVE_OPENSSL)
+   return a_Tls_openssl_write(conn, buf, len);
+#elif defined(HAVE_MBEDTLS)
+   return a_Tls_mbedtls_write(conn, buf, len);
+#else
+# error "no TLS library found but ENABLE_TLS set"
+#endif
+}