chardev: Add websocket support

New option "websocket" added to allow using WebSocket protocol for
chardev socket backend.
Example:
    -chardev socket,websocket,server,id=...

Signed-off-by: Julia Suvorova <jusual@mail.ru>
Message-Id: <20181018223501.21683-3-jusual@mail.ru>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
diff --git a/qemu-options.hx b/qemu-options.hx
index 08f8516..38c7a97 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -2414,9 +2414,9 @@
     "-chardev help\n"
     "-chardev null,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
     "-chardev socket,id=id[,host=host],port=port[,to=to][,ipv4][,ipv6][,nodelay][,reconnect=seconds]\n"
-    "         [,server][,nowait][,telnet][,reconnect=seconds][,mux=on|off]\n"
+    "         [,server][,nowait][,telnet][,websocket][,reconnect=seconds][,mux=on|off]\n"
     "         [,logfile=PATH][,logappend=on|off][,tls-creds=ID] (tcp)\n"
-    "-chardev socket,id=id,path=path[,server][,nowait][,telnet][,reconnect=seconds]\n"
+    "-chardev socket,id=id,path=path[,server][,nowait][,telnet][,websocket][,reconnect=seconds]\n"
     "         [,mux=on|off][,logfile=PATH][,logappend=on|off] (unix)\n"
     "-chardev udp,id=id[,host=host],port=port[,localaddr=localaddr]\n"
     "         [,localport=localport][,ipv4][,ipv6][,mux=on|off]\n"
@@ -2544,7 +2544,7 @@
 A void device. This device will not emit any data, and will drop any data it
 receives. The null backend does not take any options.
 
-@item -chardev socket,id=@var{id}[,@var{TCP options} or @var{unix options}][,server][,nowait][,telnet][,reconnect=@var{seconds}][,tls-creds=@var{id}]
+@item -chardev socket,id=@var{id}[,@var{TCP options} or @var{unix options}][,server][,nowait][,telnet][,websocket][,reconnect=@var{seconds}][,tls-creds=@var{id}]
 
 Create a two-way stream socket, which can be either a TCP or a unix socket. A
 unix socket will be created if @option{path} is specified. Behaviour is
@@ -2558,6 +2558,9 @@
 @option{telnet} specifies that traffic on the socket should interpret telnet
 escape sequences.
 
+@option{websocket} specifies that the socket uses WebSocket protocol for
+communication.
+
 @option{reconnect} sets the timeout for reconnecting on non-server sockets when
 the remote end goes away.  qemu will delay this many seconds and then attempt
 to reconnect.  Zero disables reconnecting, and is the default.
@@ -3106,6 +3109,10 @@
 sequence.  Typically in unix telnet you do it with Control-] and then
 type "send break" followed by pressing the enter key.
 
+@item websocket:@var{host}:@var{port},server[,nowait][,nodelay]
+The WebSocket protocol is used instead of raw tcp socket. The port acts as
+a WebSocket server. Client mode is not supported.
+
 @item unix:@var{path}[,server][,nowait][,reconnect=@var{seconds}]
 A unix domain socket is used instead of a tcp socket.  The option works the
 same as if you had specified @code{-serial tcp} except the unix domain socket