vnc: support reload x509 certificates for vnc

This patch add vnc_display_reload_certs() to support
update x509 certificates.

Signed-off-by: Zihao Chang <changzihao1@huawei.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20210316075845.1476-3-changzihao1@huawei.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

include/ui/console.h

@@ -476,6 +476,7 @@ int vnc_display_password(const char *id, const char *password);
 int vnc_display_pw_expire(const char *id, time_t expires);
 void vnc_parse(const char *str);
 int vnc_init_func(void *opaque, QemuOpts *opts, Error **errp);
+bool vnc_display_reload_certs(const char *id,  Error **errp);
 
 /* input.c */
 int index_from_key(const char *key, size_t key_length);

ui/vnc.c

@@ -585,6 +585,34 @@ VncInfo2List *qmp_query_vnc_servers(Error **errp)
     return prev;
 }
 
+bool vnc_display_reload_certs(const char *id, Error **errp)
+{
+    VncDisplay *vd = vnc_display_find(id);
+    QCryptoTLSCredsClass *creds = NULL;
+
+    if (!vd) {
+        error_setg(errp, "Can not find vnc display");
+        return false;
+    }
+
+    if (!vd->tlscreds) {
+        error_setg(errp, "vnc tls is not enable");
+        return false;
+    }
+
+    creds = QCRYPTO_TLS_CREDS_GET_CLASS(OBJECT(vd->tlscreds));
+    if (creds->reload == NULL) {
+        error_setg(errp, "%s doesn't support to reload TLS credential",
+                   object_get_typename(OBJECT(vd->tlscreds)));
+        return false;
+    }
+    if (!creds->reload(vd->tlscreds, errp)) {
+        return false;
+    }
+
+    return true;
+}
+
 /* TODO
    1) Get the queue working for IO.
    2) there is some weirdness when using the -S option (the screen is grey