IPv6
[IP]

Select the best IPv6 source address for a given destination IPv6 address.

This implementation follows RFC 6724 Sec. 5 to the following extent:

• Rules 1, 2, 3: fully implemented
• Rules 4, 5, 5.5: not applicable
• Rule 6: not implemented
• Rule 7: not applicable
• Rule 8: limited to "prefer /64 subnet match over non-match"

For Rule 2, we deliberately deviate from RFC 6724 Sec. 3.1 by considering ULAs to be of smaller scope than global addresses, to avoid that a preferred ULA is picked over a deprecated global address when given a global address as destination, as that would likely result in broken two-way communication.

As long as temporary addresses are not supported (as used in Rule 7), a proper implementation of Rule 8 would obviate the need to implement Rule 6.

Parameters:

netif	the netif on which to send a packet
dest	the destination we are trying to reach

Returns:

the most suitable source address to use, or NULL if no suitable source address is found

Definition at line 227 of file lwip_ip6.c.