Re: [PATCH v5 3/4] qapi/monitor: allow VNC display id in set/expire_password

[Markus Armbruster]

Stefan Reiter <s.reiter@proxmox.com> writes:

> It is possible to specify more than one VNC server on the command line,
> either with an explicit ID or the auto-generated ones à la "default",
> "vnc2", "vnc3", ...
>
> It is not possible to change the password on one of these extra VNC
> displays though. Fix this by adding a "display" parameter to the
> "set_password" and "expire_password" QMP and HMP commands.
>
> For HMP, the display is specified using the "-d" value flag.
>
> For QMP, the schema is updated to explicitly express the supported
> variants of the commands with protocol-discriminated unions.
>
> Suggested-by: Markus Armbruster <armbru@redhat.com>
> Signed-off-by: Stefan Reiter <s.reiter@proxmox.com>
> ---
>  hmp-commands.hx    |  24 +++++-----
>  monitor/hmp-cmds.c |  51 ++++++++++++++++++---
>  monitor/qmp-cmds.c |  44 +++++++++---------
>  qapi/ui.json       | 112 +++++++++++++++++++++++++++++++++++----------
>  4 files changed, 170 insertions(+), 61 deletions(-)
>
> diff --git a/hmp-commands.hx b/hmp-commands.hx
> index cf723c69ac..d78e4cfc47 100644
> --- a/hmp-commands.hx
> +++ b/hmp-commands.hx
> @@ -1514,33 +1514,35 @@ ERST
>  
>      {
>          .name       = "set_password",
> -        .args_type  = "protocol:s,password:s,connected:s?",
> -        .params     = "protocol password action-if-connected",
> +        .args_type  = "protocol:s,password:s,display:-dS,connected:s?",
> +        .params     = "protocol password [-d display] [action-if-connected]",
>          .help       = "set spice/vnc password",
>          .cmd        = hmp_set_password,
>      },
>  
>  SRST
> -``set_password [ vnc | spice ] password [ action-if-connected ]``
> -  Change spice/vnc password.  *action-if-connected* specifies what
> -  should happen in case a connection is established: *fail* makes the
> -  password change fail.  *disconnect* changes the password and
> +``set_password [ vnc | spice ] password [ -d display ] [ action-if-connected 
> ]``
> +  Change spice/vnc password.  *display* can be used with 'vnc' to specify
> +  which display to set the password on.  *action-if-connected* specifies
> +  what should happen in case a connection is established: *fail* makes
> +  the password change fail.  *disconnect* changes the password and
>    disconnects the client.  *keep* changes the password and keeps the
>    connection up.  *keep* is the default.
>  ERST
>  
>      {
>          .name       = "expire_password",
> -        .args_type  = "protocol:s,time:s",
> -        .params     = "protocol time",
> +        .args_type  = "protocol:s,time:s,display:-dS",
> +        .params     = "protocol time [-d display]",
>          .help       = "set spice/vnc password expire-time",
>          .cmd        = hmp_expire_password,
>      },
>  
>  SRST
> -``expire_password [ vnc | spice ]`` *expire-time*
> -  Specify when a password for spice/vnc becomes
> -  invalid. *expire-time* accepts:
> +``expire_password [ vnc | spice ] expire-time [ -d display ]``
> +  Specify when a password for spice/vnc becomes invalid.
> +  *display* behaves the same as in ``set_password``.
> +  *expire-time* accepts:
>  
>    ``now``
>      Invalidate password instantly.
> diff --git a/monitor/hmp-cmds.c b/monitor/hmp-cmds.c
> index 0ff18ebb3c..79549596e4 100644
> --- a/monitor/hmp-cmds.c
> +++ b/monitor/hmp-cmds.c
> @@ -1451,19 +1451,40 @@ void hmp_set_password(Monitor *mon, const QDict 
> *qdict)
>  {
>      const char *protocol  = qdict_get_str(qdict, "protocol");
>      const char *password  = qdict_get_str(qdict, "password");
> +    const char *display = qdict_get_try_str(qdict, "display");
>      const char *connected = qdict_get_try_str(qdict, "connected");
>      Error *err = NULL;
>      DisplayProtocol proto;
> -    SetPasswordAction conn;
> +
> +    SetPasswordOptions opts = {
> +        .password = g_strdup(password),
> +        .u.vnc.display = NULL,
> +    };
>  
>      proto = qapi_enum_parse(&DisplayProtocol_lookup, protocol,
>                              DISPLAY_PROTOCOL_VNC, &err);
> -    if (!!connected) {
> -        conn = qapi_enum_parse(&SetPasswordAction_lookup, connected,
> -                               SET_PASSWORD_ACTION_KEEP, &err);
> +    if (err) {
> +        goto out;
> +    }
> +    opts.protocol = proto;
> +
> +    if (proto == DISPLAY_PROTOCOL_VNC) {
> +        opts.u.vnc.has_display = !!display;
> +        opts.u.vnc.display = g_strdup(display);
> +    } else if (proto == DISPLAY_PROTOCOL_SPICE) {
> +        opts.u.spice.has_connected = !!connected;
> +        opts.u.spice.connected =
> +            qapi_enum_parse(&SetPasswordAction_lookup, connected,
> +                            SET_PASSWORD_ACTION_KEEP, &err);
> +        if (err) {
> +            goto out;
> +        }
>      }
>  
> -    qmp_set_password(proto, password, !!connected, conn, &err);
> +    qmp_set_password(&opts, &err);
> +
> +out:

Aha, you're fixing the crash bug I pointed out in review of PATCH 2.
Also in hmp_expire_password() below.

> +    qapi_free_SetPasswordOptions(&opts);
>      hmp_handle_error(mon, err);
>  }
>  
> @@ -1471,13 +1492,31 @@ void hmp_expire_password(Monitor *mon, const QDict 
> *qdict)
>  {
>      const char *protocol  = qdict_get_str(qdict, "protocol");
>      const char *whenstr = qdict_get_str(qdict, "time");
> +    const char *display = qdict_get_try_str(qdict, "display");
>      Error *err = NULL;
>      DisplayProtocol proto;
>  
> +    ExpirePasswordOptions opts = {
> +        .time = g_strdup(whenstr),
> +        .u.vnc.display = NULL,
> +    };
> +
>      proto = qapi_enum_parse(&DisplayProtocol_lookup, protocol,
>                              DISPLAY_PROTOCOL_VNC, &err);
> +    if (err) {
> +        goto out;
> +    }
> +    opts.protocol = proto;
>  
> -    qmp_expire_password(proto, whenstr, &err);
> +    if (proto == DISPLAY_PROTOCOL_VNC) {
> +        opts.u.vnc.has_display = !!display;
> +        opts.u.vnc.display = g_strdup(display);
> +    }

Attempts to use -d with spice are silently ignored.  Do we care?

> +
> +    qmp_expire_password(&opts, &err);
> +
> +out:
> +    qapi_free_ExpirePasswordOptions(&opts);
>      hmp_handle_error(mon, err);
>  }
>  
> diff --git a/monitor/qmp-cmds.c b/monitor/qmp-cmds.c
> index f1746a31fb..b0630d00ab 100644
> --- a/monitor/qmp-cmds.c
> +++ b/monitor/qmp-cmds.c
> @@ -163,34 +163,35 @@ void qmp_system_wakeup(Error **errp)
>      qemu_system_wakeup_request(QEMU_WAKEUP_REASON_OTHER, errp);
>  }
>  
> -void qmp_set_password(DisplayProtocol protocol, const char *password,
> -                      bool has_connected, SetPasswordAction connected,
> -                      Error **errp)
> +void qmp_set_password(SetPasswordOptions *opts, Error **errp)
>  {
> -    int disconnect_if_connected = 0;
> -    int fail_if_connected = 0;
> -    int rc;
> +    bool disconnect_if_connected = false;
> +    bool fail_if_connected = false;
> +    int rc = 0;
>  
> -    if (has_connected) {
> -        fail_if_connected = connected == SET_PASSWORD_ACTION_FAIL;
> -        disconnect_if_connected = connected == 
> SET_PASSWORD_ACTION_DISCONNECT;
> -    }
> -
> -    if (protocol == DISPLAY_PROTOCOL_SPICE) {
> +    if (opts->protocol == DISPLAY_PROTOCOL_SPICE) {
>          if (!qemu_using_spice(errp)) {
>              return;
>          }
> -        rc = qemu_spice.set_passwd(password, fail_if_connected,
> +        if (opts->u.spice.has_connected) {
> +            fail_if_connected =
> +                opts->u.spice.connected == SET_PASSWORD_ACTION_FAIL;
> +            disconnect_if_connected =
> +                opts->u.spice.connected == SET_PASSWORD_ACTION_DISCONNECT;
> +        }

For an optional member FOO, you may rely on "!has_FOO implies FOO is all
zero bits".  When FOO is an enum, "is all zero bits" means "first
member".  In this case: !has_connected implies connected ==
SET_PASSWORD_ACTION_FAIL.

This lets you simplify the code to

    bool disconnect_if_connected = connected == SET_PASSWORD_ACTION_DISCONNECT;
    bool fail_if_connected = connected == SET_PASSWORD_ACTION_FAIL;

I'd go one step further, and eliminate the variables, just like you did
already for VNC...

> +        rc = qemu_spice.set_passwd(opts->password, fail_if_connected,
>                                     disconnect_if_connected);
> -    } else if (protocol == DISPLAY_PROTOCOL_VNC) {
> -        if (fail_if_connected || disconnect_if_connected) {
> +    } else if (opts->protocol == DISPLAY_PROTOCOL_VNC) {
> +        if (opts->u.vnc.connected != SET_PASSWORD_ACTION_KEEP) {

... here.

>              /* vnc supports "connected=keep" only */
>              error_setg(errp, QERR_INVALID_PARAMETER, "connected");
>              return;
>          }
>          /* Note that setting an empty password will not disable login through
>           * this interface. */
> -        rc = vnc_display_password(NULL, password);
> +        rc = vnc_display_password(
> +                opts->u.vnc.has_display ? opts->u.vnc.display : NULL,
> +                opts->password);

When FOO is a pointer, "is all zero bits" means "null pointer".  In this
case: !ops->u.vnc.has_display implies opts->u.vnc.display == NULL.
Simplify:

           rc = vnc_display_password(opts->u.vnc.display, opts->password);

>      }
>  
>      if (rc != 0) {
> @@ -198,11 +199,11 @@ void qmp_set_password(DisplayProtocol protocol, const 
> char *password,
>      }
>  }
>  
> -void qmp_expire_password(DisplayProtocol protocol, const char *whenstr,
> -                         Error **errp)
> +void qmp_expire_password(ExpirePasswordOptions *opts, Error **errp)
>  {
>      time_t when;
>      int rc;
> +    const char* whenstr = opts->time;

Style: const char *whenstr

>  
>      if (strcmp(whenstr, "now") == 0) {
>          when = 0;
> @@ -214,13 +215,14 @@ void qmp_expire_password(DisplayProtocol protocol, 
> const char *whenstr,
>          when = strtoull(whenstr, NULL, 10);
>      }
>  
> -    if (protocol == DISPLAY_PROTOCOL_SPICE) {
> +    if (opts->protocol == DISPLAY_PROTOCOL_SPICE) {
>          if (!qemu_using_spice(errp)) {
>              return;
>          }
>          rc = qemu_spice.set_pw_expire(when);
> -    } else if (protocol == DISPLAY_PROTOCOL_VNC) {
> -        rc = vnc_display_pw_expire(NULL, when);
> +    } else if (opts->protocol == DISPLAY_PROTOCOL_VNC) {
> +        rc = vnc_display_pw_expire(
> +                opts->u.vnc.has_display ? opts->u.vnc.display : NULL, when);
>      }
>  
>      if (rc != 0) {
> diff --git a/qapi/ui.json b/qapi/ui.json
> index 15cc19dcc5..17939d0dda 100644
> --- a/qapi/ui.json
> +++ b/qapi/ui.json
> @@ -39,20 +39,61 @@
>    'data': [ 'fail', 'disconnect', 'keep' ] }
>  
>  ##
> -# @set_password:
> +# @SetPasswordOptions:
>  #
> -# Sets the password of a remote display session.
> +# Data required to set a new password on a display server protocol.

Suggest "Options for set_password", for consistency with how you
document SetPasswordOptionsSpice and SetPasswordOptionsVnc.

>  #
>  # @protocol: - 'vnc' to modify the VNC server password
>  #            - 'spice' to modify the Spice server password
>  #
>  # @password: the new password
>  #
> -# @connected: how to handle existing clients when changing the
> -#             password.  If nothing is specified, defaults to 'keep'
> -#             'fail' to fail the command if clients are connected
> -#             'disconnect' to disconnect existing clients
> -#             'keep' to maintain existing clients
> +# Since: 6.2
> +#
> +##
> +{ 'union': 'SetPasswordOptions',
> +  'base': { 'protocol': 'DisplayProtocol',
> +            'password': 'str' },
> +  'discriminator': 'protocol',
> +  'data': { 'vnc': 'SetPasswordOptionsVnc',
> +            'spice': 'SetPasswordOptionsSpice' } }
> +
> +##
> +# @SetPasswordOptionsSpice:
> +#
> +# Options for set_password specific to the SPICE procotol.
> +#
> +# @connected: How to handle existing clients when changing the
> +#             password. If nothing is specified, defaults to 'keep'.
> +#
> +# Since: 6.2
> +#
> +##
> +{ 'struct': 'SetPasswordOptionsSpice',
> +  'data': { '*connected': 'SetPasswordAction' } }
> +
> +##
> +# @SetPasswordOptionsVnc:
> +#
> +# Options for set_password specific to the VNC procotol.
> +#
> +# @display: The id of the display where the password should be changed.
> +#           Defaults to the first.
> +#
> +# @connected: How to handle existing clients when changing the
> +#             password.
> +#
> +# Since: 6.2
> +#
> +##
> +{ 'struct': 'SetPasswordOptionsVnc',
> +  'data': { '*display': 'str',
> +            '*connected': 'SetPasswordAction' }}
> +
> +##
> +# @set_password:
> +#
> +# Sets the password of a remote display session.

Good opportunity to make the docs a bit more consistent: "of a remote
display server".  Matches expire_password, and feels like an improvement
to me.

>  #
>  # Returns: - Nothing on success
>  #          - If Spice is not enabled, DeviceNotFound
> @@ -66,18 +107,16 @@
>  # <- { "return": {} }
>  #
>  ##
> -{ 'command': 'set_password',
> -  'data': { 'protocol': 'DisplayProtocol',
> -            'password': 'str',
> -            '*connected': 'SetPasswordAction' } }
> +{ 'command': 'set_password', 'boxed': true, 'data': 'SetPasswordOptions' }
>  
>  ##
> -# @expire_password:
> +# @ExpirePasswordOptions:
>  #
> -# Expire the password of a remote display server.
> -#
> -# @protocol: the name of the remote display protocol 'vnc' or 'spice'
> +# Data required to set password expiration on a display server protocol.

Suggest "Options for expire_password", for consistency with how you
document ExpirePasswordOptionsVnc.

>  #
> +# @protocol: - 'vnc' to modify the VNC server expiration
> +#            - 'spice' to modify the Spice server expiration
> +
>  # @time: when to expire the password.
>  #
>  #        - 'now' to expire the password immediately
> @@ -85,16 +124,45 @@
>  #        - '+INT' where INT is the number of seconds from now (integer)
>  #        - 'INT' where INT is the absolute time in seconds
>  #
> -# Returns: - Nothing on success
> -#          - If @protocol is 'spice' and Spice is not active, DeviceNotFound
> -#
> -# Since: 0.14
> -#
>  # Notes: Time is relative to the server and currently there is no way to
>  #        coordinate server time with client time.  It is not recommended to
>  #        use the absolute time version of the @time parameter unless you're
>  #        sure you are on the same machine as the QEMU instance.
>  #
> +# Since: 6.2
> +#
> +##
> +{ 'union': 'ExpirePasswordOptions',
> +  'base': { 'protocol': 'DisplayProtocol',
> +            'time': 'str' },
> +  'discriminator': 'protocol',
> +  'data': { 'vnc': 'ExpirePasswordOptionsVnc' } }
> +
> +##
> +# @ExpirePasswordOptionsVnc:
> +#
> +# Options for expire_password specific to the VNC procotol.
> +#
> +# @display: The id of the display where the expiration should be changed.
> +#           Defaults to the first.
> +#
> +# Since: 6.2
> +#
> +##
> +
> +{ 'struct': 'ExpirePasswordOptionsVnc',
> +  'data': { '*display': 'str' } }
> +
> +##
> +# @expire_password:
> +#
> +# Expire the password of a remote display server.
> +#
> +# Returns: - Nothing on success
> +#          - If @protocol is 'spice' and Spice is not active, DeviceNotFound
> +#
> +# Since: 0.14
> +#
>  # Example:
>  #
>  # -> { "execute": "expire_password", "arguments": { "protocol": "vnc",
> @@ -102,9 +170,7 @@
>  # <- { "return": {} }
>  #
>  ##
> -{ 'command': 'expire_password',
> -  'data': { 'protocol': 'DisplayProtocol',
> -            'time': 'str' } }
> +{ 'command': 'expire_password', 'boxed': true, 'data': 
> 'ExpirePasswordOptions' }
>  
>  ##
>  # @screendump: