Cannot connect to mosquitto broker

[VaclavSynacek]

Hello,
this might be my basic misunderstanding, but I am unable to use this library to connect to mosquitto mqtt broker.

On the client side I get:
WARNING: MQTT error: connection timed out (waiting for :CONNACK)

On mosquitto side I get:
1573232854: New connection from 127.0.0.1 on port 1883.
1573232861: Socket error on client <unknown>, disconnecting.

So cl-mqtt is somehow reaching the broker, but the handshake is not completed.

Tested with cl-mqtt a7028bc on 2 different machines:

• sbcl 1.5.8.debian, mosquitto 1.6.7-1, Linux 5.2.0-3 amd64
• sbcl 1.3.7.debian, mosquitto 1.4.10, Linux 4.19.66 armv6l

with only slightly modified example form README (I am not using swank, so no cl-async-repl):

(ql:quickload :cl-async)
(ql:quickload :cl-mqtt)
(defpackage :mqtt-player
  (:use :cl :mqtt :bb))
(in-package :mqtt-player)

(defun test-it (host port)
  (bb:alet ((conn (mqtt:connect
                   host
                   :port port
                   :client-id "mqtt-player"
                   :on-message #'(lambda (message)
                                   (format t "~%RECEIVED: ~s~%"
                                           (babel:octets-to-string
                                            (mqtt:mqtt-message-payload message)
                                            :encoding :utf-8))))))
    (bb:walk
      (mqtt:subscribe conn "/a/#")
      (mqtt:subscribe conn "/b/#")
      (mqtt:publish conn "/a/b" "whatever1")
      (mqtt:unsubscribe conn "/a/#")
      (mqtt:publish conn "/a/b" "whatever2")
      (mqtt:publish conn "/b/c" "foobar")
      (as:with-delay (1)
        (mqtt:disconnect conn))))
  (values))

(as:with-event-loop ()
  (test-it "localhost" 1883))