mosquitto_pub: exit if broker actively refuses a connection

Fixes eclipse/mosquitto#1904

If the broker rejects the connection, as opposed to the broker being
down, then there is no hope to establish a connection.  This adds a
status flag so we can signal to the loop that we should just exit.

Signed-off-by: Dan White <dan.white@valpo.edu>

client/pub_client.c

@@ -180,7 +180,8 @@ void my_connect_callback(struct mosquitto *mosq, void *obj, int result, int flag
 			}else{
 				err_printf(&cfg, "Connection error: %s\n", mosquitto_connack_string(result));
 			}
-			mosquitto_disconnect_v5(mosq, 0, cfg.disconnect_props);
+			// let the loop know that this is an unrecoverable connection
+			status = STATUS_NOHOPE;
 		}
 	}
 }
@@ -252,6 +253,10 @@ int pub_stdin_line_loop(struct mosquitto *mosq)
 #endif
 		}
 
+		if(status == STATUS_NOHOPE){
+			return MOSQ_ERR_CONN_REFUSED;
+		}
+
 		if(status == STATUS_CONNACK_RECVD){
 			pos = 0;
 			read_len = line_buf_len;

client/pub_shared.h

@@ -21,6 +21,7 @@ Contributors:
 #define STATUS_WAITING 2
 #define STATUS_DISCONNECTING 3
 #define STATUS_DISCONNECTED 4
+#define STATUS_NOHOPE 5
 
 extern int mid_sent;
 extern struct mosq_config cfg;