fix(rumqttd/protocol/v5): Parse ConnAck and UnsubAck packets instead of panicking

[izik1]

If re-adding the _ => unreachable!() is desired, let me know. I can't think of any benefit to it so I removed it.

Type of change

• Bug fix (non-breaking change which fixes an issue)

Checklist:

• Formatted with cargo fmt
• Make an entry to CHANGELOG.md if it's relevant to the users of the library. If it's not relevant mention why.
  • I have zero clue what to write in the changelog entry for this, so I currently haven't written anything

[swanandx]

broker can never send a connect packet, and hence, it can never read an ConnAck ( same with unsuback ). Hence it isn't required and is unreachable.

[izik1]

It's absolutely reachable, a non compliant (malicious) client can send a ConnAck/UnsubAck specifically because it knows a rumqttd broker is running (this happens before auth is checked, since checking auth requires reading a packet) and would panic the connection. Perhaps the correct course of action would instead be an error?

I got the body of the fix from "do what v4 does" and it does the same thing (hence writing a PR instead of an issue):

rumqtt/rumqttd/src/protocol/v4/mod.rs

Line 318 in 8af9d88

PacketType::ConnAck => Packet::ConnAck(connack::read(fixed_header, packet)?, None),

rumqtt/rumqttd/src/protocol/v4/mod.rs

Line 328 in 8af9d88

PacketType::UnsubAck => Packet::UnsubAck(unsuback::read(fixed_header, packet)?, None),

if this is undesirable a change to v4 parsing is required as well.

[swanandx]

oh yeah, you are right, we should not panic. Instead of error, lets parse it for now as you mentioned as do same in v4.

can we move handling connack right after connect ( like in v4, and same for unsuback ).

also, we can remove that _ => unreachable from v4 as well right?

for changelog, you can add under fix that "handle Connack and unsuback packets properly instead of panic" or something similar ( i'm not that good at this either haha )

thanks for pointing it out and the fix!

[coveralls]

Pull Request Test Coverage Report for Build 8208492265

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

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Details

• 0 of 4 (0.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.004%) to 37.827%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
rumqttd/src/protocol/v5/mod.rs	0	4	0.0%

Totals
Change from base Build 8063409788:	-0.004%
Covered Lines:	6255
Relevant Lines:	16536

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💛 - Coveralls

[izik1]

Yeah, I can do all that.