No searching for end-points when responding to mDNS/LLMNR/NBNS

[evpopov]

Description

When name queries (mDNS/LLMNR/NBNS) need to be responded to, the current code searches for an end-point to use when sending the response. This PR gets rid of this search and uses the end-point on which the original request was received. This removes the possibility of a malformed request causing responses to be sent on other interfaces.
A lot more details can be found in #1042

I am not sure if any test are being affected by this change.
I have also removed prvFindEndPointOnNetMask( NetworkBufferDescriptor_t * pxNetworkBuffer ) since it is no longer used. I also believe the whole premise of having a function that searches for and end-point to be used for a response is incorrect. Any response should be using the end-point of the original request, but this is just my opinion. Please let me know what you think and if you believe I should keep this function in the codebase even though it is no longer used.

Related Issue

#1042

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[htibosch]

Thank you @evpopov

[htibosch]

As we already wrote in your issue #1042 I totally agree with this choice. And also I agree that the endpoint receiving a request should be used for the reply as well.
I already tested this PR and it looks good, both IPV4 and IPv6 connections, and for A and AAAA DNS requests.

[n9wxu]

Please take a look at the PR checks and correct the issues.

[htibosch]

@n9wxu wrote:

Please take a look at the PR checks and correct the issues.

To @evpopov, adapted unit tests: FreeRTOS_DNS_Parser_utest.zip

[evpopov]

Thanks @htibosch !
I really appreciate you jumping in and helping with the updated unit test

[htibosch]

I saw that the coverage was still no 100% and repaired that in these source files:

changes_coverage.zip

source\FreeRTOS_DNS_Parser.c
test\unit-test\FreeRTOS_DNS_Parser\FreeRTOS_DNS_Parser_utest.c

I had forgotten the new configASSERT().

I could also make this simplification:

-    pxIPHeader->ulSourceIPAddress = ( pxEndPoint != NULL ) ? pxEndPoint->ipv4_settings.ulIPAddress : 0U;
+    pxIPHeader->ulSourceIPAddress = pxEndPoint->ipv4_settings.ulIPAddress;

because pxEndPoint is proven to be not NULL.

[tony-josi-aws]

/bot run formatting