Add `mosquitto_kick_client_by_clientid()` and `mosquitto_kick_client_by_username()`

These can be used by plugins to disconnect clients.

ChangeLog.txt

@@ -18,6 +18,8 @@ Broker:
   plugins to determine which version of MQTT a client has connected with.
 - Send DISCONNECT with `malformed-packet` reason code on invalid PUBLISH, 
   SUBSCRIBE, and UNSUBSCRIBE packets.
+- Add `mosquitto_kick_client_by_clientid()` and `mosquitto_kick_client_by_username()`
+  functions, which can be used by plugins to disconnect clients.
 
 Client library:
 - Client no longer generates random client ids for v3.1.1 clients, these are

lib/mosquitto.h

@@ -101,6 +101,7 @@ enum mosq_err_t {
 	MOSQ_ERR_TIMEOUT = 27,
 	MOSQ_ERR_RETAIN_NOT_SUPPORTED = 28,
 	MOSQ_ERR_TOPIC_ALIAS_INVALID = 29,
+	MOSQ_ERR_ADMINISTRATIVE_ACTION = 30,
 };
 
 /* Option values */

src/linker-macosx.syms

@@ -9,6 +9,8 @@ _mosquitto_client_protocol
 _mosquitto_client_protocol_version
 _mosquitto_client_sub_count
 _mosquitto_client_username
+_mosquitto_kick_client_by_clientid
+_mosquitto_kick_client_by_username
 _mosquitto_log_printf
 _mosquitto_property_add_binary
 _mosquitto_property_add_byte

src/linker.syms

@@ -10,6 +10,8 @@
 	mosquitto_client_protocol_version;
 	mosquitto_client_sub_count;
 	mosquitto_client_username;
+	mosquitto_kick_client_by_clientid;
+	mosquitto_kick_client_by_username;
 	mosquitto_log_printf;
 	mosquitto_plugin_publish;
 	mosquitto_property_add_binary;

src/loop.c

@@ -300,12 +300,19 @@ void do_disconnect(struct mosquitto_db *db, struct mosquitto *context, int reaso
 					case MOSQ_ERR_KEEPALIVE:
 						log__printf(NULL, MOSQ_LOG_NOTICE, "Client %s has exceeded timeout, disconnecting.", id);
 						break;
+					case MOSQ_ERR_ADMINISTRATIVE_ACTION:
+						log__printf(NULL, MOSQ_LOG_NOTICE, "Client %s been disconnected by administrative action.", id);
+						break;
 					default:
 						log__printf(NULL, MOSQ_LOG_NOTICE, "Socket error on client %s, disconnecting.", id);
 						break;
 				}
 			}else{
-				log__printf(NULL, MOSQ_LOG_NOTICE, "Client %s disconnected.", id);
+				if(reason == MOSQ_ERR_ADMINISTRATIVE_ACTION){
+					log__printf(NULL, MOSQ_LOG_NOTICE, "Client %s been disconnected by administrative action.", id);
+				}else{
+					log__printf(NULL, MOSQ_LOG_NOTICE, "Client %s disconnected.", id);
+				}
 			}
 		}
 		mux__delete(db, context);

src/mosquitto_broker.h

@@ -179,6 +179,46 @@ const char *mosquitto_client_username(const struct mosquitto *client);
 int mosquitto_set_username(struct mosquitto *client, const char *username);
 
 
+/* =========================================================================
+ *
+ * Client control
+ *
+ * ========================================================================= */
+
+/* Function: mosquitto_kick_client_by_clientid
+ *
+ * Forcefully disconnect a client from the broker.
+ *
+ * If clientid != NULL, then the client with the matching client id is
+ *   disconnected from the broker.
+ * If clientid == NULL, then all clients are disconnected from the broker.
+ *
+ * If with_will == true, then if the client has a Last Will and Testament
+ *   defined then this will be sent. If false, the LWT will not be sent.
+ */
+int mosquitto_kick_client_by_clientid(const char *clientid, bool with_will);
+
+/* Function: mosquitto_kick_client_by_username
+ *
+ * Forcefully disconnect a client from the broker.
+ *
+ * If username != NULL, then all clients with a matching username are kicked
+ *   from the broker.
+ * If username == NULL, then all clients that do not have a username are
+ *   kicked.
+ *
+ * If with_will == true, then if the client has a Last Will and Testament
+ *   defined then this will be sent. If false, the LWT will not be sent.
+ */
+int mosquitto_kick_client_by_username(const char *username, bool with_will);
+
+
+/* =========================================================================
+ *
+ * Publishing functions
+ *
+ * ========================================================================= */
+
 /* Function: mosquitto_broker_publish
  *
  * Publish a message from within a plugin.

src/plugin.c

@@ -20,6 +20,9 @@ Contributors:
 #include "mosquitto_internal.h"
 #include "mosquitto_broker.h"
 #include "memory_mosq.h"
+#include "mqtt_protocol.h"
+#include "send_mosq.h"
+#include "util_mosq.h"
 #include "utlist.h"
 
 #ifdef WITH_TLS
@@ -230,3 +233,59 @@ int mosquitto_set_username(struct mosquitto *client, const char *username)
 	}
 }
 
+
+static void disconnect_client(struct mosquitto_db *db, struct mosquitto *context, bool with_will)
+{
+	if(context->protocol == mosq_p_mqtt5){
+		send__disconnect(context, MQTT_RC_ADMINISTRATIVE_ACTION, NULL);
+	}
+	if(with_will == false){
+		mosquitto__set_state(context, mosq_cs_disconnecting);
+	}
+	do_disconnect(db, context, MOSQ_ERR_ADMINISTRATIVE_ACTION);
+}
+
+int mosquitto_kick_client_by_clientid(const char *clientid, bool with_will)
+{
+	struct mosquitto_db *db;
+	struct mosquitto *ctxt, *ctxt_tmp;
+
+	db = mosquitto__get_db();
+	if(clientid == NULL){
+		HASH_ITER(hh_sock, db->contexts_by_sock, ctxt, ctxt_tmp){
+			disconnect_client(db, ctxt, with_will);
+		}
+		return MOSQ_ERR_SUCCESS;
+	}else{
+		HASH_FIND(hh_id, db->contexts_by_id, clientid, strlen(clientid), ctxt);
+		if(ctxt){
+			disconnect_client(db, ctxt, with_will);
+			return MOSQ_ERR_SUCCESS;
+		}else{
+			return MOSQ_ERR_NOT_FOUND;
+		}
+	}
+}
+
+int mosquitto_kick_client_by_username(const char *username, bool with_will)
+{
+	struct mosquitto_db *db;
+	struct mosquitto *ctxt, *ctxt_tmp;
+
+	db = mosquitto__get_db();
+
+	if(username == NULL){
+		HASH_ITER(hh_sock, db->contexts_by_sock, ctxt, ctxt_tmp){
+			if(ctxt->username == NULL){
+				disconnect_client(db, ctxt, with_will);
+			}
+		}
+	}else{
+		HASH_ITER(hh_sock, db->contexts_by_sock, ctxt, ctxt_tmp){
+			if(ctxt->username != NULL && !strcmp(ctxt->username, username)){
+				disconnect_client(db, ctxt, with_will);
+			}
+		}
+	}
+	return MOSQ_ERR_SUCCESS;
+}