Introduce a 'client_add' monitor command accepting an open FD

Allow client connections for VNC and socket based character
devices to be passed in over the monitor using SCM_RIGHTS.

One intended usage scenario is to start QEMU with VNC on a
UNIX domain socket. An unprivileged user which cannot access
the UNIX domain socket, can then connect to QEMU's VNC server
by passing an open FD to libvirt, which passes it onto QEMU.

 { "execute": "get_fd", "arguments": { "fdname": "myclient" } }
 { "return": {} }
 { "execute": "add_client", "arguments": { "protocol": "vnc",
                                           "fdname": "myclient",
                                           "skipauth": true } }
 { "return": {} }

In this case 'protocol' can be 'vnc' or 'spice', or the name
of a character device (eg from -chardev id=XXXX)

The 'skipauth' parameter can be used to skip any configured
VNC authentication scheme, which is useful if the mgmt layer
talking to the monitor has already authenticated the client
in another way.

* console.h: Define 'vnc_display_add_client' method
* monitor.c: Implement 'client_add' command
* qemu-char.c, qemu-char.h: Add 'qemu_char_add_client' method
* qerror.c, qerror.h: Add QERR_ADD_CLIENT_FAILED
* qmp-commands.hx: Declare 'client_add' command
* ui/vnc.c: Implement 'vnc_display_add_client' method

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/console.h b/console.h
index c09537b861..67d137384e 100644
--- a/console.h
+++ b/console.h
@@ -372,6 +372,7 @@ void cocoa_display_init(DisplayState *ds, int full_screen);
 void vnc_display_init(DisplayState *ds);
 void vnc_display_close(DisplayState *ds);
 int vnc_display_open(DisplayState *ds, const char *display);
+void vnc_display_add_client(DisplayState *ds, int csock, int skipauth);
 int vnc_display_disable_login(DisplayState *ds);
 char *vnc_display_local_addr(DisplayState *ds);
 #ifdef CONFIG_VNC