TLS support for VNC Websockets

Added TLS support to the VNC QEMU Websockets implementation.
VNC-TLS needs to be enabled for this feature to be used.

The required certificates are specified as in case of VNC-TLS
with the VNC parameter "x509=<path>".

If the server certificate isn't signed by a rooth authority it needs to
be manually imported in the browser because at least in case of Firefox
and Chrome there is no user dialog, the connection just gets canceled.

As a side note VEncrypt over Websocket doesn't work atm because TLS can't
be stacked in the current implementation. (It also didn't work before)
Nevertheless to my knowledge there is no HTML 5 VNC client which supports
it and the Websocket connection can be encrypted with regular TLS now so
it should be fine for most use cases.

Signed-off-by: Tim Hardeck <thardeck@suse.de>
Reviewed-by: Anthony Liguori <aliguori@us.ibm.com>
Message-id: 1366727581-5772-1-git-send-email-thardeck@suse.de
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

1 files changed, 63 insertions, 0 deletions

diff --git a/ui/vnc-ws.c b/ui/vnc-ws.c
index 3e30209..df89315 100644
--- a/ui/vnc-ws.c
+++ b/ui/vnc-ws.c
@@ -20,6 +20,69 @@
 
 #include "vnc.h"
 
+#ifdef CONFIG_VNC_TLS
+#include "qemu/sockets.h"
+
+static void vncws_tls_handshake_io(void *opaque);
+
+static int vncws_start_tls_handshake(struct VncState *vs)
+{
+    int ret = gnutls_handshake(vs->ws_tls.session);
+
+    if (ret < 0) {
+        if (!gnutls_error_is_fatal(ret)) {
+            VNC_DEBUG("Handshake interrupted (blocking)\n");
+            if (!gnutls_record_get_direction(vs->ws_tls.session)) {
+                qemu_set_fd_handler(vs->csock, vncws_tls_handshake_io,
+                                    NULL, vs);
+            } else {
+                qemu_set_fd_handler(vs->csock, NULL, vncws_tls_handshake_io,
+                                    vs);
+            }
+            return 0;
+        }
+        VNC_DEBUG("Handshake failed %s\n", gnutls_strerror(ret));
+        vnc_client_error(vs);
+        return -1;
+    }
+
+    VNC_DEBUG("Handshake done, switching to TLS data mode\n");
+    vs->ws_tls.wiremode = VNC_WIREMODE_TLS;
+    qemu_set_fd_handler2(vs->csock, NULL, vncws_handshake_read, NULL, vs);
+
+    return 0;
+}
+
+static void vncws_tls_handshake_io(void *opaque)
+{
+    struct VncState *vs = (struct VncState *)opaque;
+
+    VNC_DEBUG("Handshake IO continue\n");
+    vncws_start_tls_handshake(vs);
+}
+
+void vncws_tls_handshake_peek(void *opaque)
+{
+    VncState *vs = opaque;
+    long ret;
+
+    if (!vs->ws_tls.session) {
+        char peek[4];
+        ret = qemu_recv(vs->csock, peek, sizeof(peek), MSG_PEEK);
+        if (ret && (strncmp(peek, "\x16", 1) == 0
+                    || strncmp(peek, "\x80", 1) == 0)) {
+            VNC_DEBUG("TLS Websocket connection recognized");
+            vnc_tls_client_setup(vs, 1);
+            vncws_start_tls_handshake(vs);
+        } else {
+            vncws_handshake_read(vs);
+        }
+    } else {
+        qemu_set_fd_handler2(vs->csock, NULL, vncws_handshake_read, NULL, vs);
+    }
+}
+#endif /* CONFIG_VNC_TLS */
+
 void vncws_handshake_read(void *opaque)
 {
     VncState *vs = opaque;