nanocoap_sock: clean up state management

[benpicco]

Contribution description

This gets rid of the implicit additional state added by the retry_rxvariable and makes it an explicit state.
Functionality should stay the same.

Testing procedure

Issues/PRs references

[fjmolinas]

Could you provide some test output? Would be nice to see a suit test for example.

[benpicco]

Yup, still works

gnrc_uhcpc: Using 4 as border interface and 0 as wireless interface.
gnrc_uhcpc: only one interface found, skipping setup.
main(): This is RIOT! (Version: 2022.07-devel-467-g7c758-nanocoap-state_cleanup)
RIOT SUIT update example application
Running from slot 0
Image magic_number: 0x544f4952
Image Version: 0x6284de57
Image start address: 0x00004400
Header chksum: 0x8667227e

suit_coap: started.
Starting the shell

> suit: received URL: "coap://[2001:db8::1]/fw/suit_update/same54-xpro/riot.suit.latest.bin"
suit_coap: trigger received
suit_coap: downloading "coap://[2001:db8::1]/fw/suit_update/same54-xpro/riot.suit.latest.bin"
suit_coap: got manifest with size 485
suit: verifying manifest signature
suit: validated manifest version
)Manifest seq_no: 1652874915, highest available: 1652874839
suit: validated sequence number
)Formatted component name: 
Comparing manifest offset 4000 with other slot offset
Comparing manifest offset 82000 with other slot offset
validating vendor ID
Comparing 547d0d74-6d3a-5a92-9662-4881afd9407b to 547d0d74-6d3a-5a92-9662-4881afd9407b from manifest
validating vendor ID: OK
validating class id
Comparing 50244518-6a7c-5ce7-932b-88b318336c82 to 50244518-6a7c-5ce7-932b-88b318336c82 from manifest
validating class id: OK
Comparing manifest offset 4000 with other slot offset
Comparing manifest offset 82000 with other slot offset
SUIT policy check OK.
Formatted component name: 
riotboot_flashwrite: initializing update to target slot 1
Fetching firmware |█████████████████████████| 100%
Finalizing payload store
Verifying image digest
Starting digest verification against image
Install correct payload
Verified installed payload
Verifying image digest
Starting digest verification against image
Verified installed payload
Image magic_number: 0x544f4952
Image Version: 0x6284dea3
Image start address: 0x00082400
Header chksum: 0x479f02d2

suit_coap: rebooting...
----> ethos: hello received
Failed to send flush request: Operation not permitted
gnrc_uhcpc: Using 4 as border interface and 0 as wireless interface.
gnrc_uhcpc: only one interface found, skipping setup.
main(): This is RIOT! (Version: 2022.07-devel-467-g7c758-nanocoap-state_cleanup)
RIOT SUIT update example application
Running from slot 1
Image magic_number: 0x544f4952
Image Version: 0x6284dea3
Image start address: 0x00082400
Header chksum: 0x479f02d2

suit_coap: started.
Starting the shell

[fjmolinas]

ACK