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I've just installed IPv6 and connected myself to the IPv6 Internet with Windows XP. Now I want to write some programs.
I'm having trouble finding example code for IPv6 multicast. What I want is something like <http://www.ipmulticast.com/content/category/4/72/30/ >, but for IPv6 instead of IPv4.
Has anyone here programmed for IPv6?
MSDN has a good guide for making IPv6 compatible applications. Anyway, it looked like an interesting challenge, so:
Code:/* multicast_server.c
* This sample demonstrates a Windows multicast server that works with either
* IPv4 or IPv6, depending on the multicast address given.
* Requires Windows XP+/Use MSVC and platform SDK to compile.
* Troubleshoot: Make sure you have the IPv6 stack installed by running
* >ipv6 install
*
* Usage:
* multicast_server multicastip port data [ttl]
*
* Examples:
* >multicast_server 224.0.22.1 9210 HelloIPv4World
* >multicast_server ff15::1 2001 HelloIPv6World
*
* Written by tmouse, July 2005
* http://cboard.cprogramming.com/showthread.php?t=67469
*/
#include <stdio.h> /* for fprintf() */
#include <winsock2.h> /* for socket(), connect(), send(), and recv() */
#include <ws2tcpip.h> /* for ip options */
#include <stdlib.h> /* for atoi() and exit() */
#if defined(_MSC_VER)
#pragma comment(lib, "ws2_32.lib")
#endif
static void DieWithError(char* errorMessage)
{
fprintf(stderr, "%s\n", errorMessage);
exit(EXIT_FAILURE);
}
int main(int argc, char *argv[])
{
SOCKET sock; /* Socket */
WSADATA wsaData; /* For WSAStartup */
char* multicastIP; /* Arg: IP Multicast address */
char* multicastPort; /* Arg: Server port */
char* sendString; /* Arg: String to multicast */
size_t sendStringLen; /* Length of string to multicast */
DWORD multicastTTL; /* Arg: TTL of multicast packets */
ADDRINFO* multicastAddr; /* Multicast address */
ADDRINFO hints = { 0 }; /* Hints for name lookup */
if ( WSAStartup(MAKEWORD(2, 2), &wsaData) != 0)
{
DieWithError("WSAStartup() failed");
}
if ( argc < 4 || argc > 5 )
{
fprintf(stderr, "Usage: %s <Multicast Address> <Port> <Send String> [<TTL>]\n", argv[0]);
exit(EXIT_FAILURE);
}
multicastIP = argv[1]; /* First arg: multicast IP address */
multicastPort = argv[2]; /* Second arg: multicast port */
sendString = argv[3]; /* Third arg: String to multicast */
multicastTTL = (argc == 5 ? /* Fourth arg: If supplied, use command-line */
atoi(argv[4]) : 1); /* specified TTL, else use default TTL of 1 */
sendStringLen = strlen(sendString); /* Find length of sendString */
/* Resolve destination address for multicast datagrams */
hints.ai_family = PF_UNSPEC;
hints.ai_socktype = SOCK_DGRAM;
hints.ai_flags = AI_NUMERICHOST;
if ( getaddrinfo(multicastIP, multicastPort, &hints, &multicastAddr) != 0 )
{
DieWithError("getaddrinfo() failed");
}
printf("Using %s\n", multicastAddr->ai_family == PF_INET6 ? "IPv6" : "IPv4");
/* Create socket for sending multicast datagrams */
if ( (sock = socket(multicastAddr->ai_family, multicastAddr->ai_socktype, 0)) == INVALID_SOCKET )
{
DieWithError("socket() failed");
}
/* Set TTL of multicast packet */
if ( setsockopt(sock,
multicastAddr->ai_family == PF_INET6 ? IPPROTO_IPV6 : IPPROTO_IP,
multicastAddr->ai_family == PF_INET6 ? IPV6_MULTICAST_HOPS : IP_MULTICAST_TTL,
(char*) &multicastTTL, sizeof(multicastTTL)) != 0 )
{
DieWithError("setsockopt() failed");
}
for (;;) /* Run forever */
{
if ( sendto(sock, sendString, sendStringLen, 0,
multicastAddr->ai_addr, multicastAddr->ai_addrlen) != sendStringLen )
{
DieWithError("sendto() sent a different number of bytes than expected");
}
Sleep(3000); /* Multicast sendString in datagram to clients every 3 seconds */
}
/* NOT REACHED */
freeaddrinfo(multicastAddr);
closesocket(sock);
return 0;
}
I'm not connected to an IPv6 network so I've only tested it locally.Code:/* multicast_client.c
* This sample demonstrates a Windows multicast client that works with either
* IPv4 or IPv6, depending on the multicast address given.
* Requires Windows XP+/Use MSVC and platform SDK to compile.
* Troubleshoot: Make sure you have the IPv6 stack installed by running
* >ipv6 install
*
* Usage:
* multicast_client multicastip port
*
* Examples:
* >multicast_client 224.0.22.1 9210
* >multicast_client ff15::1 2001
*
* Written by tmouse, July 2005
* http://cboard.cprogramming.com/showthread.php?t=67469
*/
#include <stdio.h> /* for printf() and fprintf() */
#include <winsock2.h> /* for socket(), connect(), sendto(), and recvfrom() */
#include <ws2tcpip.h> /* for ip_mreq */
#include <stdlib.h> /* for atoi() and exit() */
#include <string.h> /* for memset() */
#include <time.h> /* for timestamps */
#if defined(_MSC_VER)
#pragma comment(lib, "ws2_32.lib")
#endif
void DieWithError(char* errorMessage)
{
fprintf(stderr, "%s\n", errorMessage);
exit(EXIT_FAILURE);
}
int main(int argc, char* argv[])
{
SOCKET sock; /* Socket */
WSADATA wsaData; /* For WSAStartup */
char* multicastIP; /* Arg: IP Multicast Address */
char* multicastPort; /* Arg: Port */
ADDRINFO* multicastAddr; /* Multicast Address */
ADDRINFO* localAddr; /* Local address to bind to */
ADDRINFO hints = { 0 }; /* Hints for name lookup */
if ( WSAStartup(MAKEWORD(2, 2), &wsaData) != 0)
{
DieWithError("WSAStartup() failed");
}
if ( argc != 3 )
{
fprintf(stderr,"Usage: %s <Multicast IP> <Multicast Port>\n", argv[0]);
exit(EXIT_FAILURE);
}
multicastIP = argv[1]; /* First arg: Multicast IP address */
multicastPort = argv[2]; /* Second arg: Multicast port */
/* Resolve the multicast group address */
hints.ai_family = PF_UNSPEC;
hints.ai_flags = AI_NUMERICHOST;
if ( getaddrinfo(multicastIP, NULL, &hints, &multicastAddr) != 0 )
{
DieWithError("getaddrinfo() failed");
}
printf("Using %s\n", multicastAddr->ai_family == PF_INET6 ? "IPv6" : "IPv4");
/* Get a local address with the same family (IPv4 or IPv6) as our multicast group */
hints.ai_family = multicastAddr->ai_family;
hints.ai_socktype = SOCK_DGRAM;
hints.ai_flags = AI_PASSIVE; /* Return an address we can bind to */
if ( getaddrinfo(NULL, multicastPort, &hints, &localAddr) != 0 )
{
DieWithError("getaddrinfo() failed");
}
/* Create socket for receiving datagrams */
if ( (sock = socket(localAddr->ai_family, localAddr->ai_socktype, 0)) == INVALID_SOCKET )
{
DieWithError("socket() failed");
}
/* Bind to the multicast port */
if ( bind(sock, localAddr->ai_addr, localAddr->ai_addrlen) != 0 )
{
DieWithError("bind() failed");
}
/* Join the multicast group. We do this seperately depending on whether we
* are using IPv4 or IPv6. WSAJoinLeaf is supposed to be IP version agnostic
* but it looks more complex than just duplicating the required code. */
if ( multicastAddr->ai_family == PF_INET &&
multicastAddr->ai_addrlen == sizeof(struct sockaddr_in) ) /* IPv4 */
{
struct ip_mreq multicastRequest; /* Multicast address join structure */
/* Specify the multicast group */
memcpy(&multicastRequest.imr_multiaddr,
&((struct sockaddr_in*)(multicastAddr->ai_addr))->sin_addr,
sizeof(multicastRequest.imr_multiaddr));
/* Accept multicast from any interface */
multicastRequest.imr_interface.s_addr = htonl(INADDR_ANY);
/* Join the multicast address */
if ( setsockopt(sock, IPPROTO_IP, IP_ADD_MEMBERSHIP, (char*) &multicastRequest, sizeof(multicastRequest)) != 0 )
{
DieWithError("setsockopt() failed");
}
}
else if ( multicastAddr->ai_family == PF_INET6 &&
multicastAddr->ai_addrlen == sizeof(struct sockaddr_in6) ) /* IPv6 */
{
struct ipv6_mreq multicastRequest; /* Multicast address join structure */
/* Specify the multicast group */
memcpy(&multicastRequest.ipv6mr_multiaddr,
&((struct sockaddr_in6*)(multicastAddr->ai_addr))->sin6_addr,
sizeof(multicastRequest.ipv6mr_multiaddr));
/* Accept multicast from any interface */
multicastRequest.ipv6mr_interface = 0;
/* Join the multicast address */
if ( setsockopt(sock, IPPROTO_IPV6, IPV6_ADD_MEMBERSHIP, (char*) &multicastRequest, sizeof(multicastRequest)) != 0 )
{
DieWithError("setsockopt() failed");
}
}
else
{
DieWithError("Neither IPv4 or IPv6");
}
freeaddrinfo(localAddr);
freeaddrinfo(multicastAddr);
for (;;) /* Run forever */
{
time_t timer;
char recvString[500]; /* Buffer for received string */
int recvStringLen; /* Length of received string */
/* Receive a single datagram from the server */
if ( (recvStringLen = recvfrom(sock, recvString, sizeof(recvString) - 1, 0, NULL, 0)) < 0 )
{
DieWithError("recvfrom() failed");
}
recvString[recvStringLen] = '\0';
/* Print the received string */
time(&timer); /* get time stamp to print with recieved data */
printf("Time Received: %.*s : %s\n", strlen(ctime(&timer)) - 1, ctime(&timer), recvString);
}
/* NOT REACHED */
closesocket(sock);
exit(EXIT_SUCCESS);
}
Thanks, I'm going to test your code later on.
I managed to write an application which worked locally on one computer. I'm having trouble with the connection to the 6bone on my other computer, so I'm not able to test it globally either.
Hmm, when I use the address ff15::1 I recieve each datagram two times on my laptop (SP2 Home), but when I try the same program on my stationary (SP2 Prof) I recieve each datagram only once.
I'm using freenet6 and I have been assigned a /48 prefix. One stationary computer is a router which advertises addresses to every computer on the local network.
It seems to be working -- if I go to www.ipv6.org with my laptop it shows
Now, if I want to use global multicast, which address should I use? According to this document, http://www.ipv6style.jp/en/tech/2004...041001_p.shtml , it seems that you can create a multicast address from your prefix.Quote:
You are using IPv6 from 2001:5c0:89fb:0:20e:35ff:fe54:78af
So if my prefix is 2001:5c0:89fb, could I use ff3e:20:2001:5c0:89fb :: 1 as a multicast address? It doesn't seem to be working.
from chapter 25 of tcip with ipv6:
it may be your device causing the problem.Quote:
IPv6 Supported Address Types
One important change in the addressing model of IPv6 is the address types supported.
IPv4 supported three address types: unicast, multicast, and broadcast. Of these,
the vast majority of actual traffic was unicast. IP multicast support was not widely
deployed until many years after the Internet was established and it continues to be
hampered by various issues. Use of broadcast in IP had to be severely restricted for
performance reasons (we don’t want any device to be able to broadcast across the
entire Internet!).
IPv6 also supports three address types, but with the following changes:
Unicast Addresses These are standard unicast addresses as in IPv4, one per host
interface.
Multicast Addresses These are addresses that represent various groups of IP
devices. A message sent to a multicast address goes to all devices in the group. IPv6
includes much better multicast features and many more multicast addresses than
IPv4. Since multicast under IPv4 was hampered in large part due to lack of support
of the feature by many hardware devices, support for multicasting is a required, not
optional, part of IPv6.
Anycast Addresses Anycast addressing is used when a message must be sent to any
member of a group, but does not need to be sent to all of them. Usually the member
of the group that is easiest to reach will be sent the message. One common
example of how anycast addressing could be used is in load sharing among a group
of routers in an organization.
Broadcast addressing as a distinct addressing method is gone in IPv6. Broadcast
functionality is implemented using multicast addressing to groups of devices. A
multicast group to which all nodes belong can be used for broadcasting in a network,
for example.
KEY CONCEPT IPv6 has unicast and multicast addresses like IPv4. There is, however, no
distinct concept of a broadcast address in IPv6. A new type of address, the anycast address, has
been added to allow a message to be sent to any one member of a group of devices.
for the addressing part:
from same source. :)Quote:
Table 25-1: IPv6 Address Space Allocations
Leading Bits
Fraction of Total
IPv6 Address Space Allocation
0000 0000 1/256 Unassigned (Includes special addresses such as the
unspecified and loopback addresses)
0000 0001 1/256 Unassigned
0000 001 1/128 Reserved for NSAP address allocation
0000 01 1/64 Unassigned
0000 1 1/32 Unassigned
0001 1/16 Unassigned
001 1/8 Global unicast addresses
010 1/8 Unassigned
011 1/8 Unassigned
100 1/8 Unassigned
101 1/8 Unassigned
110 1/8 Unassigned
1110 1/16 Unassigned
1111 0 1/32 Unassigned
1111 10 1/64 Unassigned
1111 110 1/128 Unassigned
1111 1110 0 1/512 Unassigned
1111 1110 10 1/1024 Link-local unicast addresses
1111 1110 11 1/1024 Site-local unicast addresses
1111 1111 1/256 Multicast addresses
hope this helps you solve the problem
the second quote is actually table data, sorry that the formatting makes it hard to follow.
They don't mean user hardware devices -- they mean routers on the Internet. It is easy for a client to support multicast, but harder for routers.