Using the mosquitto_sub -R flag causes failed subscription.

[benbarbour]

I'm running mosquitto 1.6.3 and if I run mosquitto_sub -t root/A/B/C -C 1 -W 5 -u usr1 -P usr1Pwd -I ben -d and then before it times out I run mosquitto_pub -t root/A/B/C -m hello -u usr2 -P usr2Pwd then I get this output (after creating the given users, of course):

mosquitto_sub output

Client ben1 sending CONNECT
Client ben1 received CONNACK (0)
Client ben1 sending SUBSCRIBE (Mid: 1, Topic: root/A/B/C, QoS: 0, Options: 0x00)
Client ben1 received SUBACK
Subscribed (mid: 1): 0
Client ben1 received PUBLISH (d0, q0, r0, m0, 'root/A/B/C', ... (5 bytes))
hello
Client ben1 sending DISCONNECT

Broker logs

1563484048: New connection from 10.0.0.112 on port 1883.
1563484049: New client connected from 10.0.0.112 as ben1 (p2, c1, k60, u'usr1').
1563484050: New connection from 10.0.0.113 on port 1883.
1563484050: New client connected from 10.0.0.113 as mosq/mgwUWpjT8tcFTk5dbZ (p2, c1, k60, u'usr2').
1563484050: Client ben1 disconnected.
1563484050: Client mosq/mgwUWpjT8tcFTk5dbZ disconnected.

However, if I retry the same thing with the subscribe command changed to: mosquitto_sub -t root/A/B/C -C 1 -W 5 -u usr1 -P usr1Pwd -I ben -d -R (just add the -R flag) then this is the output:

mosquitto_sub output

Client ben1 sending CONNECT
Client ben1 received CONNACK (0)
Client ben1 sending SUBSCRIBE (Mid: 1, Topic: root/A/B/C, QoS: 0, Options: 0x20)
Client ben1 sending CONNECT
Client ben1 received CONNACK (0)
Client ben1 sending SUBSCRIBE (Mid: 2, Topic: root/A/B/C, QoS: 0, Options: 0x20)
Client ben1 sending CONNECT
Client ben1 received CONNACK (0)
Client ben1 sending SUBSCRIBE (Mid: 3, Topic: root/A/B/C, QoS: 0, Options: 0x20)
Client ben1 sending CONNECT
Client ben1 received CONNACK (0)
Client ben1 sending SUBSCRIBE (Mid: 4, Topic: root/A/B/C, QoS: 0, Options: 0x20)
Client ben1 sending CONNECT
Client ben1 received CONNACK (0)
Client ben1 sending SUBSCRIBE (Mid: 5, Topic: root/A/B/C, QoS: 0, Options: 0x20)
Client ben1 sending CONNECT
Client ben1 received CONNACK (0)
Client ben1 sending SUBSCRIBE (Mid: 6, Topic: root/A/B/C, QoS: 0, Options: 0x20)
Client ben1 sending CONNECT
Client ben1 received CONNACK (0)
Client ben1 sending SUBSCRIBE (Mid: 7, Topic: root/A/B/C, QoS: 0, Options: 0x20)
Client ben1 sending CONNECT
Client ben1 received CONNACK (0)
Client ben1 sending SUBSCRIBE (Mid: 8, Topic: root/A/B/C, QoS: 0, Options: 0x20)
Client ben1 sending CONNECT
Client ben1 received CONNACK (0)
Client ben1 sending SUBSCRIBE (Mid: 9, Topic: root/A/B/C, QoS: 0, Options: 0x20)
Client ben1 sending CONNECT
Client ben1 received CONNACK (0)
Client ben1 sending SUBSCRIBE (Mid: 10, Topic: root/A/B/C, QoS: 0, Options: 0x20)
Client ben1 sending CONNECT
Client ben1 received CONNACK (0)
Client ben1 sending SUBSCRIBE (Mid: 11, Topic: root/A/B/C, QoS: 0, Options: 0x20)
Client ben1 sending CONNECT
Client ben1 received CONNACK (0)
Client ben1 sending SUBSCRIBE (Mid: 12, Topic: root/A/B/C, QoS: 0, Options: 0x20)
Client ben1 sending CONNECT
Client ben1 received CONNACK (0)
Client ben1 sending SUBSCRIBE (Mid: 13, Topic: root/A/B/C, QoS: 0, Options: 0x20)
Client ben1 sending CONNECT
Client ben1 received CONNACK (0)
Client ben1 sending SUBSCRIBE (Mid: 14, Topic: root/A/B/C, QoS: 0, Options: 0x20)
Client ben1 sending CONNECT
Client ben1 received CONNACK (0)
Client ben1 sending SUBSCRIBE (Mid: 15, Topic: root/A/B/C, QoS: 0, Options: 0x20)

Broker logs

1563484353: New connection from 10.0.0.114 on port 1883.
1563484353: New client connected from 10.0.0.114 as ben1 (p2, c1, k60, u'usr1').
1563484353: Invalid QoS in subscription command from 10.0.0.114, disconnecting.
1563484353: Socket error on client ben1, disconnecting.
1563484354: New connection from 10.0.0.114 on port 1883.
1563484354: New client connected from 10.0.0.114 as ben1 (p2, c1, k60, u'usr1').
1563484354: Invalid QoS in subscription command from 10.0.0.114, disconnecting.
1563484354: Socket error on client ben1, disconnecting.
1563484354: New connection from 10.0.0.115 on port 1883.
1563484354: New client connected from 10.0.0.115 as mosq/3RUZczbMdfei1nh0rA (p2, c1, k60, u'usr2').
1563484354: Client mosq/3RUZczbMdfei1nh0rA disconnected.
1563484355: New connection from 10.0.0.114 on port 1883.
1563484355: New client connected from 10.0.0.114 as ben1 (p2, c1, k60, u'usr1').
1563484355: Invalid QoS in subscription command from 10.0.0.114, disconnecting.
1563484355: Socket error on client ben1, disconnecting.
1563484356: New connection from 10.0.0.114 on port 1883.
1563484356: New client connected from 10.0.0.114 as ben1 (p2, c1, k60, u'usr1').
1563484356: Invalid QoS in subscription command from 10.0.0.114, disconnecting.
1563484356: Socket error on client ben1, disconnecting.
1563484357: New connection from 10.0.0.114 on port 1883.
1563484357: New client connected from 10.0.0.114 as ben1 (p2, c1, k60, u'usr1').
1563484357: Invalid QoS in subscription command from 10.0.0.114, disconnecting.
1563484357: Socket error on client ben1, disconnecting.
1563484358: New connection from 10.0.0.114 on port 1883.
1563484358: New client connected from 10.0.0.114 as ben1 (p2, c1, k60, u'usr1').
1563484358: Invalid QoS in subscription command from 10.0.0.114, disconnecting.
1563484358: Socket error on client ben1, disconnecting.
1563484359: New connection from 10.0.0.114 on port 1883.
1563484359: New client connected from 10.0.0.114 as ben1 (p2, c1, k60, u'usr1').
1563484359: Invalid QoS in subscription command from 10.0.0.114, disconnecting.
1563484359: Socket error on client ben1, disconnecting.
1563484360: New connection from 10.0.0.114 on port 1883.
1563484360: New client connected from 10.0.0.114 as ben1 (p2, c1, k60, u'usr1').
1563484360: Invalid QoS in subscription command from 10.0.0.114, disconnecting.
1563484360: Socket error on client ben1, disconnecting.
1563484361: New connection from 10.0.0.114 on port 1883.
1563484361: New client connected from 10.0.0.114 as ben1 (p2, c1, k60, u'usr1').
1563484361: Invalid QoS in subscription command from 10.0.0.114, disconnecting.
1563484361: Socket error on client ben1, disconnecting.
1563484362: New connection from 10.0.0.114 on port 1883.
1563484362: New client connected from 10.0.0.114 as ben1 (p2, c1, k60, u'usr1').
1563484362: Invalid QoS in subscription command from 10.0.0.114, disconnecting.
1563484362: Socket error on client ben1, disconnecting.
1563484363: New connection from 10.0.0.114 on port 1883.
1563484363: New client connected from 10.0.0.114 as ben1 (p2, c1, k60, u'usr1').
1563484363: Invalid QoS in subscription command from 10.0.0.114, disconnecting.
1563484363: Socket error on client ben1, disconnecting.
1563484364: New connection from 10.0.0.114 on port 1883.
1563484364: New client connected from 10.0.0.114 as ben1 (p2, c1, k60, u'usr1').
1563484364: Invalid QoS in subscription command from 10.0.0.114, disconnecting.
1563484364: Socket error on client ben1, disconnecting.
1563484365: New connection from 10.0.0.114 on port 1883.
1563484365: New client connected from 10.0.0.114 as ben1 (p2, c1, k60, u'usr1').
1563484365: Invalid QoS in subscription command from 10.0.0.114, disconnecting.
1563484365: Socket error on client ben1, disconnecting.
1563484366: New connection from 10.0.0.114 on port 1883.
1563484366: New client connected from 10.0.0.114 as ben1 (p2, c1, k60, u'usr1').
1563484366: Invalid QoS in subscription command from 10.0.0.114, disconnecting.
1563484366: Socket error on client ben1, disconnecting.
1563484367: New connection from 10.0.0.114 on port 1883.
1563484367: New client connected from 10.0.0.114 as ben1 (p2, c1, k60, u'usr1').
1563484367: Invalid QoS in subscription command from 10.0.0.114, disconnecting.
1563484367: Socket error on client ben1, disconnecting.

[benbarbour]

Just poking around near the "Invalid QoS" message and wondering if the protocol version is somehow mismatched between the subscribing client and the broker?

The logs show that I'm subscribing with options "0x20" when the -R flag is passed. It looks like in protocol v5 those options are bit flags that might have something to do with that flag, but the options are assumed to consist only of the QoS in protocol version 3. :/

[ralight]

You're right, it is setting MQTT v5 subscription options on v3 subscriptions. It should be checking the protocol before setting those options. I've pushed a change that has the library ignore any subscription options if the client isn't using MQTT v5.