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Support IPv6 Unique Local Addresses #1294

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@marcusb
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@marcusb marcusb commented Oct 10, 2025

Description

This change correctly identifies ULAs with the fc00::/7 prefix, so that they can be assigned to endpoints and correctly matched to received packets.

Test Steps

Configured the application with two IPv6 endpoints, one link-local and one ULA.
Ping the ULA address. Replies would be echoed back from the link-local address.

After fixing, both IPv6 addresses can be pinged, and replies come from the target address.

Checklist:

  • I have tested my changes. No regression in existing tests.
  • I have modified and/or added unit-tests to cover the code changes in this Pull Request.

Related Issue

#1293

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

@htibosch
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htibosch commented Oct 10, 2025

Marcus, that is quick, you also adapted the UT's.

I checked the changes in your PR, the essence is the addition of a new packet type:

 typedef enum
 {
     eIPv6_Global,        /* 001           */
     eIPv6_LinkLocal,     /* 1111 1110 10  */
     eIPv6_SiteLocal,     /* 1111 1110 11  */
+    eIPv6_UniqueLocal,   /* 1111 110      */
     eIPv6_Multicast,     /* 1111 1111     */
     eIPv6_Loopback,      /* 1111 (::1)    */
     eIPv6_Unknown        /* Not implemented. */
 }
 IPv6_Type_t;

Then I tested it by pinging two addresses:

IP-address of my laptop: fd12:3456:789a::2
IP-address of my Zynq: fd12:3456:789a::3

I am able to ping the Zynq.
However Zynq is not able to ping the laptop, I don't know why.

htibosch
htibosch approved these changes Oct 10, 2025
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Integration testing: it took me a while to realise that my laptop's antivirus is stopping packets to the new ULA address fd12:3456:789a::3.
I saw the packets arriving in Wireshark, but the ICMP/ping requests were ignored.

It looks all good to me, so I approve your PR.

Thanks,

@htibosch
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htibosch commented Oct 12, 2025

I tested one more thing, using FileZilla to access a local drive, using an ULA and TCP.
It worked as expected, connecting from fd12:3456:789a::2 to fd12:3456:789a::3.

Remember that FileZilla expects IPv6 addresses between square brackets: [fd12:3456:789a::3].

@marcusb marcusb force-pushed the ula branch 2 times, most recently from 3058111 to d68e986 Compare October 16, 2025 03:18
@AniruddhaKanhere AniruddhaKanhere enabled auto-merge (rebase) November 11, 2025 21:40
@marcusb @AniruddhaKanhere
Support IPv6 Unique Local Addresses
fd74f08 
This change correctly identifies ULAs with the fc00::/7 prefix, so
that they can be assigned to endpoints and correctly matched to
received packets.
@AniruddhaKanhere AniruddhaKanhere enabled auto-merge (squash) November 11, 2025 21:44
@AniruddhaKanhere AniruddhaKanhere enabled auto-merge (rebase) November 11, 2025 21:44
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@AniruddhaKanhere AniruddhaKanhere AniruddhaKanhere approved these changes

@moninom1 moninom1 moninom1 approved these changes

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@htibosch htibosch htibosch approved these changes

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@marcusb @htibosch @AniruddhaKanhere @moninom1