OTA: Thread end device (Requestor) crashes if it cannot reach the Provider

[mykrupp]

Problem

Expected behavior: announce-ota-provider should error out when no Provider node ID has been registered. One reason that the Provider node ID would not be registered is if the provider has not been commissioned over thread

In a Thread network when the end device receives the Announce OTA Provider command and the Provider node ID indicated in that command is not reachable, the end device crashes. The function HandleNodeIdResolve in Discovery_ImplPlatform.cpp is passed a DnssdService pointer that contains incomplete information. Attributes mKey, mData contain null fields and mDataSize seems uninitialized.

Steps to reproduce:

• Commission an OTA Requestor node onto a Thread network
• Issue an AnnonceOTAProvider command passing an invalid (nonexistent) id as the Provider address:chip-tool otasoftwareupdaterequestor announce-ota-provider [invalidId] 0 0 0 2 0

Or follow the steps in https://github.com/selissia/connectedhomeip/edit/master/examples/ota-requestor-app/efr32/README.md without commissioning the Provider.

Call stack in Ozone:

Hardfault register details:

Proposed Solution

Either a null check around the provider node ID fields, or an error code indicating that the provider has not been comissioned.

[selissia]

In this scenario the Provider is residing off the Thread network:
Provider----IP----OTBR----Thread----EndDevice

[holbrookt]

@selissia should this issue be assigned to you as it's efr32? If not, can you help assign?

[selissia]

@holbrookt Yes, this is a DNS issue not specific to EFR32. As such I initially assigned it to @vivien-apple but @woody-apple unassigned it, I'm not sure why.

[holbrookt]

Maybe an automated script? Feel free to reassign if you think that's right

[selissia]

Fixed by the above PR