[Dnsmasq-discuss] [PATCH] Add new extensible D-Bus signal
Victorien Molle
victorien.molle at wifirst.fr
Fri Dec 6 09:53:54 GMT 2019
For our usage, we need to have more informations sent over D-Bus such as the interface
name, the vendor class identifier and the lease expiration time.
To achieve this, we add a new D-Bus signal "DhcpLeaseNotification" which exports the
requested informations as a dictionnary.
It also has the advantage to be flexible if someone wants to add a new entry in the
future.
Note: in order to get leases extradata be populated, we enabled this feature if D-Bus
is enabled in configuration file (this was enabled in the past only if a script was
ran on leases updates).
Here is an example of the obtained result with a Python3 program:
''' Define our D-Bus callback '''
def cb(action, ipaddr, hwaddr, hostname, info):
print(f'Action: {action}')
print(f'IP: {ipaddr}')
print(f'Hostname: {hostname}')
for k in info:
print(f'{k}: {info.get(k)}')
''' Connect to signal DhcpLeaseNotification on interface uk.org.thekelleys.dnsmasq '''
DNSMasq.listen('DhcpLeaseNotification', callback=cb)
''' Run GLib loop '''
GLib.MainLoop().run()
''' When DNSMasq receives a DHCP request, here is the result: '''
Action: 3
IP: 192.168.1.100
Hostname: Nucleus.nucle.us
interface: br-mgmt
vendor_class: LaGrosseBiche
expiration: 1575667431
Signed-off-by: Victorien Molle <victorien.molle at wifirst.fr>
Signed-off-by: Florent Fourcot <florent.fourcot at wifirst.fr>
---
dbus/DBus-interface | 9 ++++
src/dbus.c | 108 ++++++++++++++++++++++++++++++++++++++++++++
src/rfc2131.c | 2 +-
3 files changed, 118 insertions(+), 1 deletion(-)
diff --git a/dbus/DBus-interface b/dbus/DBus-interface
index 954c5b9..ed42551 100644
--- a/dbus/DBus-interface
+++ b/dbus/DBus-interface
@@ -273,14 +273,23 @@ DhcpLeaseAdded
---------------
This signal is emitted when a DHCP lease for a given IP address is created.
+This will also trigger the DhcpLeaseNotification signal.
DhcpLeaseDeleted
----------------
This signal is emitted when a DHCP lease for a given IP address is deleted.
+This will also trigger the DhcpLeaseNotification signal.
DhcpLeaseUpdated
----------------
This signal is emitted when a DHCP lease for a given IP address is updated.
+This will also trigger the DhcpLeaseNotification signal.
+
+DhcpLeaseNotification
+---------------------
+
+This signal is emitted when a DHCP lease action is triggered. It exports,
+as a dictionnary, more informations than the other signals.
diff --git a/src/dbus.c b/src/dbus.c
index c0ce903..01cf3ea 100644
--- a/src/dbus.c
+++ b/src/dbus.c
@@ -70,6 +70,13 @@ const char* introspection_xml_template =
" <arg name=\"hwaddr\" type=\"s\"/>\n"
" <arg name=\"hostname\" type=\"s\"/>\n"
" </signal>\n"
+" <signal name=\"DhcpLeaseNotification\">\n"
+" <arg name=\"notification_type\" type=\"i\"/>\n"
+" <arg name=\"ipaddr\" type=\"s\"/>\n"
+" <arg name=\"hwaddr\" type=\"s\"/>\n"
+" <arg name=\"hostname\" type=\"s\"/>\n"
+" <arg name=\"lease_info\" type=\"a{sv}\"/>\n"
+" </signal>\n"
#ifdef HAVE_DHCP
" <method name=\"AddDhcpLease\">\n"
" <arg name=\"ipaddr\" type=\"s\"/>\n"
@@ -98,6 +105,12 @@ struct watch {
struct watch *next;
};
+struct lease_info {
+ char *key;
+ char *fmt;
+ char dbus_type;
+ DBusBasicValue value;
+};
static dbus_bool_t add_watch(DBusWatch *watch, void *data)
{
@@ -828,6 +841,98 @@ void check_dbus_listeners()
}
#ifdef HAVE_DHCP
+/*
+ As this function is called by emit_dbus_signal, we already have access to ipaddr, hwaddr and hostname attributes
+ NOTE: connection attribute is currently not NULL as it is verified by emit_dbus_signal
+*/
+void emit_dhcplease_notification(DBusConnection *connection, int action, struct dhcp_lease *lease, char *ipaddr, char *hwaddr, char *hostname)
+{
+ DBusMessageIter array, dict, iter, variant;
+ dbus_uint64_t expires = lease->expires;
+ unsigned char *buf = lease->extradata;
+ dbus_int32_t act_type = action;
+ char *interface, *vendor_class;
+ DBusMessage* message = NULL;
+ struct lease_info *info;
+ int allocated = 0;
+ struct irec *it;
+
+ interface = "";
+ for (it = daemon->interfaces; it != NULL; it = it->next)
+ {
+ if (it->index == lease->last_interface)
+ {
+ interface = it->name;
+ break;
+ }
+ }
+
+ vendor_class = "";
+ /* As defined in rfc2131.c, the first data is the vendor class even if it is empty */
+ if (buf && *buf != 0)
+ {
+ vendor_class = (char*)whine_malloc(lease->extradata_len + 1);
+ if (vendor_class)
+ {
+ allocated = 1;
+ strncpy(vendor_class, (const char*)buf, (lease->extradata_len));
+ }
+ else
+ {
+ vendor_class = "";
+ }
+ }
+
+ struct lease_info infos[] = {{.key = "interface", .fmt = "s", .dbus_type = DBUS_TYPE_STRING, .value.str = interface},
+ {.key = "vendor_class", .fmt = "s", .dbus_type = DBUS_TYPE_STRING, .value.str = vendor_class},
+ {.key = "expiration", .fmt = "t", .dbus_type = DBUS_TYPE_UINT64, .value.u64 = expires},
+ {NULL, NULL, DBUS_TYPE_INVALID, 0}
+ };
+
+ if (!(message = dbus_message_new_signal(DNSMASQ_PATH, daemon->dbus_name, "DhcpLeaseNotification")))
+ goto out;
+
+ dbus_message_iter_init_append(message, &iter);
+ dbus_message_iter_append_basic(&iter, DBUS_TYPE_INT32, &act_type);
+ dbus_message_iter_append_basic(&iter, DBUS_TYPE_STRING, &ipaddr);
+ dbus_message_iter_append_basic(&iter, DBUS_TYPE_STRING, &hwaddr);
+ dbus_message_iter_append_basic(&iter, DBUS_TYPE_STRING, &hostname);
+ dbus_message_iter_open_container(&iter, DBUS_TYPE_ARRAY, "{sv}", &array);
+ for (info = infos; info->key; info++) {
+ dbus_message_iter_open_container(&array, DBUS_TYPE_DICT_ENTRY, NULL, &dict);
+ dbus_message_iter_append_basic(&dict, DBUS_TYPE_STRING, &info->key);
+ dbus_message_iter_open_container(&dict, DBUS_TYPE_VARIANT, info->fmt, &variant);
+ switch (info->dbus_type)
+ {
+ case DBUS_TYPE_STRING:
+ dbus_message_iter_append_basic(&variant, info->dbus_type, &info->value.str);
+ break;
+
+ case DBUS_TYPE_UINT64:
+ dbus_message_iter_append_basic(&variant, info->dbus_type, &info->value.u64);
+ break;
+
+ default:
+ dbus_message_iter_abandon_container(&dict, &variant);
+ dbus_message_iter_abandon_container_if_open(&array, &dict);
+ dbus_message_iter_abandon_container_if_open(&iter, &array);
+ dbus_message_unref(message);
+ my_syslog(LOG_WARNING, _("Unknown D-Bus type specified for key '%s'. This will completely disable 'DhcpLeaseNotification' signal"),
+ info->key);
+ goto out;
+ }
+ dbus_message_iter_close_container(&dict, &variant);
+ dbus_message_iter_close_container(&array, &dict);
+ }
+ dbus_message_iter_close_container(&iter, &array);
+ dbus_connection_send(connection, message, NULL);
+ dbus_message_unref(message);
+
+out:
+ if (vendor_class && allocated)
+ free(vendor_class);
+}
+
void emit_dbus_signal(int action, struct dhcp_lease *lease, char *hostname)
{
DBusConnection *connection = (DBusConnection *)daemon->dbus;
@@ -878,6 +983,9 @@ void emit_dbus_signal(int action, struct dhcp_lease *lease, char *hostname)
dbus_connection_send(connection, message, NULL);
dbus_message_unref(message);
+
+ /* Now emit a notification with more informations */
+ emit_dhcplease_notification(connection, action, lease, daemon->addrbuff, mac, hostname);
}
#endif
diff --git a/src/rfc2131.c b/src/rfc2131.c
index 0058747..0cea3c4 100644
--- a/src/rfc2131.c
+++ b/src/rfc2131.c
@@ -1366,7 +1366,7 @@ size_t dhcp_reply(struct dhcp_context *context, char *iface_name, int int_index,
lease->flags |= LEASE_CHANGED;
#ifdef HAVE_SCRIPT
- if (daemon->lease_change_command)
+ if (daemon->lease_change_command || daemon->dbus)
{
struct dhcp_netid *n;
--
2.24.0
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