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Told the application of a failed IPv6 address only once it is removed - #494
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When duplicate address detection fails, _nx_icmpv6_DAD_failure marks the address invalid, calls the application's address change callback with NX_IPV6_ADDRESS_DAD_FAILURE, and only then removes the address from its interface's address list. The callback runs on the IP thread and is free to send. A send to a multicast group joined on that interface looks for a source address at the head of the interface's list, finds the address just marked invalid, and fails the NX_ASSERT in _nxd_ipv6_interface_find that such an address is never there. The IP thread then sleeps forever and the IP instance is dead. Measured on dev in v6_full_build: the callback's nxd_udp_socket_send never returns and the IP thread is left in TX_SLEEP. No other address change callback runs with the address half changed; DAD success, stateless configuration, prefix expiry, manual set and delete, and the IPv4 ones all call after the change is complete. The callback is now made after the address is off the list, with the same arguments. Its existing users -- the DHCPv6 client and netx_icmpv6_DAD_test -- record the index and address and wake a thread, and both are unchanged by the move. The product file header is unchanged. netx_ipv6_dad_failure_notify_send_test sets on one IP instance an address another already owns, sends from the callback to a group joined on the interface, and checks that the callback returns and the IP instance still answers a ping. Without the change it fails; with it, it passes. Assisted-by: Claude Code (Opus 5.5) <noreply@anthropic.com>
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Problem
When duplicate address detection fails,
_nx_icmpv6_DAD_failuremarks the address invalid(
nx_icmpv6_DAD_failure.c:87), calls the application's address change callback withNX_IPV6_ADDRESS_DAD_FAILURE(:96), and only then removes the address from its interface'saddress list (
:105,:116).The callback runs on the IP thread, and the user guide puts no restriction on what it may do. If it
sends to a multicast group joined on that interface,
_nxd_ipv6_interface_findtakes the head of theinterface's address list as the source, finds the address just marked invalid, and fails
NX_ASSERT((*ipv6_addr) -> nxd_ipv6_address_valid)(nxd_ipv6_interface_find.c:122).NX_ASSERT_FAILsleeps forever, so the IP thread stops and the IP instance is dead.Reproduced on
devinv6_full_build: the callback'snxd_udp_socket_sendnever returns and the IPthread is left in
TX_SLEEP(state 4). The same inv6_full_secure_build.The other address change callbacks were checked: DAD success, stateless address configuration,
prefix expiry, manual set and delete, and the IPv4 ones all call after the change is complete.
Change
The callback is made after the address has been removed from the list, with the same arguments.
The DHCPv6 client and
netx_icmpv6_DAD_test, the existing users, record the index and address andwake a thread, and neither depends on the address still being on the list.
Test
netx_ipv6_dad_failure_notify_send_test: one IP instance sets an address another already owns, sodetection fails; its callback sends to a group joined on that interface. The test checks that the
callback returns and that the IP instance still answers a ping. It fails without the change and
passes with it. It runs where
NX_ENABLE_IPV6_ADDRESS_CHANGE_NOTIFYandNX_ENABLE_IPV6_MULTICASTare both set (
v6_full_build,v6_full_secure_build) and reports N/A elsewhere.Control on
dev: without the change the test fails inv6_full_buildandv6_full_secure_build; with it, it passes.netx_icmpv6_DAD_test, which checks the DAD failurenotification itself, passes with the change in
v6_full_build,v6_full_secure_build,v6_address_change_build,v6_buildandv6_dhcp_tahi_build.Sweep: the new test ran five times in all 43 NetX Duo configurations. Result: 10 pass
(
v6_full_build,v6_full_secure_build), 205 report N/A, 0 failures — exactly the configurationswith and without both features.