Presented by R P Porwal

contents Introduction

IPv4 Client, IPv6 Server

IPv6 Client, IPv4 Server

IPv6 Address Testing Macros

IPV6_ADDRFORM Socket Option

Source Code Portability

Introduction Server and client combination

IPv4 <=> IPv4(most server and client)

IPv4 <=> IPv6

IPv6 <=> IPv4

IPv6 <=> IPv6

How IPv4 application and IPv6 application can communicate with each other.

Host are running dual stacks, both an IPv4 protocol stack and IPv6 protocol stack

IPv4 Client , IPv6 Server IPv6 dual stack server can handle both IPv4 and IPv6

clients.

This is done using IPv4-mapped IPv6 address

server create an IPv6 listening socket that is bound to the IPv6 wildcard address

IPv6

client

IPv6

server

TCP

IPv6

Data

link

Data

link

IPv4

TCP

IPv4

client

TCP

IPv4 IPv6

Data

link

Enet

hdr

IPv4

hdr

TCP

hdr

TCP

data

Enet

hdr

IPv4

hdr

TCP

hdr

TCP

data

Type0800

Type0800 Dport 8888

Dport 8888

206.62.226.42

IPv4 mapped

IPv6 address

IPv6 listening socket,

bound to 0::0, port 8888

IPv6 address

5flb:df00:ce3

e:e200:20:80

0:2b37:6426

IPv4 datagram IPv6 datagram

AF_INET

SOCK_STREAM

sockaddr_in

AF_INET

SOCK_DGRAM

sockaddr_in

AF_INET6

SOCK_DGRAM

sockaddr_in6

AF_INET6

SOCK_DGRAM

sockaddr_in6

TCP

IPv4 IPv6

UDP

IPv4 sockets

IPv6sockets

Address

returned by

accept or

recvfrom

IPv6 IPv4

IPv4 mapped

IPv6 client, IPv4 server IPv4 server start on an IPv4 only host and create an

IPv4 listening socket

IPv6 client start, call gethostbyname. IPv4 mapped IPv6 address is returned.

Using IPv4 datagram

IPv4 datagram IPv6 datagram

AF_INET

SOCK_STREAM

sockaddr_in

AF_INET

SOCK_DGRAM

sockaddr_in

AF_INET6

SOCK_DGRAM

sockaddr_in6

AF_INET6

SOCK_DGRAM

sockaddr_in6

TCP

IPv4 IPv6

UDP

IPv4 sockets

IPv6sockets

Address

for connect

or sendto

IPv6 IPv4

IPv4 mapped IPv6

IPv6 Address Testing Macros There are small class of IPv6 application that must

know whether they are talking to an IPv4 peer.

These application need to know if the peer’s address is an IPv4-mapped IPv6 address.

Twelve macro defined(참조 page 267)

IPV6_ADDRFORM Socket Option Can change a socket from one type to another,

following restriction.

An IPv4 socket can always be changed to an IPv6. Any IPv4 address already associated with the socket are converted to IPv4- mapped IPv6 address.

An IPv6 socket can changed to an IPv4 socket only if any address already associated with the socket are IPv4-mapped IPv6 address.

Int af;

socklen_t clilen;

struct sockaddr_int6 cli; /* IPv6 struct */

struct hostent *ptr;

af = AF_INT6;

Setsockopt(STDIN_FILENO, IPPROTO_IPV6,

IPV6_ADDRFORM, &af, sizeof(af));

clilen = sizeof(cli);

Getpeername(0, &cli, &clilen);

ptr = gethostbyaddr(&cli.sin6_addr, 16, AF_INET);

Converting an IPv4 to IPv6

setsockopt => change the Address format of socket from IPv4 to IPv6.

Return value is AF_INET or AF_INET6

getpeername =>return an IPv4-mapped IPv6 address

Source Code Portability #ifdefs => hard to maintain, littered …

use getaddrinfo and getnameinfo