[lwip-devel] [bug #58103] IPV6 udp_send() fails when enabling Dual Stack(IPV4 and IPv6) configuration and with multiple interface

[Simon Goldschmidt]

URL:
  <https://savannah.nongnu.org/bugs/?58103>

                 Summary: IPV6 udp_send() fails when enabling Dual Stack(IPV4
and IPv6) configuration and with multiple interface
                 Project: lwIP - A Lightweight TCP/IP stack
            Submitted by: goldsimon
            Submitted on: Thu 02 Apr 2020 06:38:24 PM UTC
                Category: UDP
                Severity: 3 - Normal
              Item Group: Faulty Behaviour
                  Status: None
                 Privacy: Public
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any
         Planned Release: None
            lwIP version: Other

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Details:

This is from lwip-users
(https://lists.nongnu.org/archive/html/lwip-devel/2020-03/msg00000.html):


Hi,

In my current project i have enabled Dual Stack (IPv4 and IPv6) with
multiple interfaces.

My query : How to send IPV6 udp packet from the second interface when source
address is 0?
I'm binding the socket with port only.

Trying the below sequence:
        - Add interface-1 to the netif list, bring up interface-1.
        - send and receive the IPv4 and IPv6 packets with interface-1.
        - Bring down interface-1.
        - Add interface-2 to netif list, bring up interface-2.
        - send and receive the IPv4 packets with interface-2.
        - send multicast link-local IPv6 packets with interface-2. udp_send() 
FAIL,
since ip6_route() returns interface as NULL.

Please give some solution. 

Thank you,





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