Issues in rewriting server side (1/2)

Port number space issues
No clear definition
e.g. relationship between the port space of TCP/IPv4 and the space of TCP/IPv6?
Order of bind(2)?
Take the safest route:
getaddrinfo(AI_PASSIVE)
issue bind(2) to all addresses
exit if none of bind(2) succeed

IPv6 wildcard bind
RFC2553: allows an AF_INET6 socket to accept IPv4 packets.
Do not rely on this - complicated specification, low portability.
Source of security holes: loophole in access control rules.
check ::ffff:1.2.3.4 as well as 1.2.3.4

SUMMARY: assume nothing