Summary: Source Code Symbols and Function Changes

The following tables cover changes in the source code symbols and functions that Socket Application programmers need to be aware of when porting code to support IPv6.

Changes to Symbols, Data Structures, and Function Calls

Table A-1 Changes to Symbols, Data Structures, and Function Calls

Search source code for:	Replace with:
Symbols
`AF_INET PF_INET`	`AF_INET6 PF_INET6`
Data Structures
`sockaddr_in u_short sin_family in_port_t sin_port sin_addr struct in_addr`	`sockaddr_in6 shorts in6_family; u_short sin6_port; uint32_t sin6_flowinfo; struct in6_addr sin6_addr; uint32_t sin6_scope_id`
`ifreq ifconf`	`struct if_laddrreq struct if_laddrconf`
Function Calls
`gethostbyname()`	`getaddrinfo() or getipnodebyname(), freeaddrinfo()`
`gethostbyaddr()`	`getipnodebyaddr(),getnameinfo(), freeaddrinfo()`
`inet_ntoa() inet_addr() or inet_aton()`	`inet_ntop() inet_pton()`

Watch for hard-coded data structure sizes

Watch for sizeof(struct sockaddr_in) = sizeof(struct sockaddr) = 16 in pre-ported applications. The IPv6 address data structure sockaddr_in6 is larger than the traditional sockaddr_in data structure.

Multicast and IPv4 Options

Table A-2 Multicast and IPv4 Options

IPv4	IPv6	Comments
`IN_CLASSA IN_CLASSB IN_CLASSC IN_CLASSD`	None. IPv6 addressing is classless.

Loopback Address

Table A-3 Loopback Address

IPv4	IPv6	Comments
`INADDR_LOOPBACK`	`in6addr_loopback`	`in6adr_loopback` is an `in6_addr` structure

Wildcard Address

Table A-4 Wildcard Address

IPv4	IPv6	Comments
`INADDR_ANY`	`in6addr_any`	`in6addr_any` is an `in6_addr` structure

Multicast Defaults

Table A-5 Multicast Defaults

IPv4	IPv6	Comments
`IP_DEFAULT_MULTICAST_LOOP IP_DEFAULT_MULTICAST_TTL`	`IPV6_DEFAULT_MULTICAST_LOOP IPV6_DEFAULT_MULTICAST_HOPS`

IPv6 Multicast Options

Table A-6 IPv6 Multicast Options

IPv4	IPv6	Comments
`IP_MULTICAST_IF IP_MULTICAST_TTL IP_MULTICAST_LOOP IP_ADD_MEMBERSHIP IP_DROP_MEMBERSHIP`	`IPV6_MULTICAST_IF` `IPV6_MULTICAST_HOPS` `IPV6_MULTICAST_LOOP IPV6_JOIN_GROUP IPV6_LEAVE_GROUP`




	NOTE: When setting the `getsockopt()` and `setsockopt()` `level` parameter, use `IPPROTO_IPV6` level for all `IPV6_*` options listed here.

IP Packet Options

Table A-7 IP Packet Options

IP_OPTIONS	IPV6_PKTOPTIONS	Comments
`IP_RECVDSTADDR IP_RECVIF`	`IPV6_DESTOPTS IPV6_HOPLIMIT IPV6_HOPOPTS IPV6_NEXTHOP IPV6_PKTINFO IPV6_PKTINFO IPV6_PKTINFO`	Receive Destination options Unicast hop limit for receiving packets Receive hop-by-hop options Set next-hop address Set packet information Return destination IP address Return received interface index
	`IPV6_RTHDR`	Send or receive routing header
`IP_TTL ip_mreq`	`IPv6_UNICAST_HOPS ipv6_IP_OPTIONSmreq`	Default unicast hop limit




	NOTE: Bundle the seven options above into a single `setsockopt()` call using `IPV6_PKTOPTIONS`.

Types of Service Options

Table A-8 Types of Service Options

IP_TOS

Still under discussion by IETF IPng working group.

Multicast Group, IP Address, and IPv6 Interface Index

Table A-9 Multicast Group, IP Address, and IPv6 Interface Index

IPv4	IPv6	Comments
`struct in_addr imr_multicast`	`struct in6_addr ipv6mr_multiaddr`	Multicast address of group
`struct in_addrimr_interface`	`uint32 ipv6mr_interface`	IPv4: local IP address of interface IPv6: interface index