Linux&Windows下的IP Multicast 开发
Multicast 不用多说，组播，既然要做multicast开发，肯定得知道multicast是什么；
windows和linux下开发的multicast的代码如下，具体的讲解，看代码注释：
<script type="text/javascript"><!-- google_ad_client = "pub-8565472114859759"; /* 180x150, 创建于 08-7-7 */ google_ad_slot = "4647145443"; google_ad_width = 180; google_ad_height = 150; //--> </script><script type="text/javascript" src="http://pagead2.googlesyndication.com/pagead/show_ads.js"> </script>
C/C++ code
/*Multicast Client.c support Linux & Windows
*Zhao.kaiyong(a)gmail.com
*http://blog.csdn.net/openhero
*可以转载，可以复制，修改，如果有修改，请给我来一封email：）谢谢
*/
注：
1.在windows中不需要特殊的设置网络；
2.在Linux下得特别注意网络的设置，有下面几个环节：
1）查看内核模块，是否已经加载了multicast支持；这个可以通过 在src目录下面 make menuconfig 查看ip 设置栏目看到；
2）查看网络是否已经加载了multicast支持；命令：ip a 可以看到现在网络支持的各个功能；
3）添加multicast 网络路由：net add -net 224.0.0.0 netmask 240.0.0.0 dev eth0
这样才能启动网络的multicast路由支持，不然只能当作broadcast处理。
windows和linux下开发的multicast的代码如下，具体的讲解，看代码注释：
<script type="text/javascript"><!-- google_ad_client = "pub-8565472114859759"; /* 180x150, 创建于 08-7-7 */ google_ad_slot = "4647145443"; google_ad_width = 180; google_ad_height = 150; //--> </script><script type="text/javascript" src="http://pagead2.googlesyndication.com/pagead/show_ads.js"> </script>
*Zhao.kaiyong(a)gmail.com
*http://blog.csdn.net/openhero
*可以转载，可以复制，修改，如果有修改，请给我来一封email：）谢谢
*/
<!-- Code highlighting produced by Actipro CodeHighlighter (freeware) http://www.CodeHighlighter.com/ -->
#include < stdio.h >
#include < stdlib.h >
#include < string .h >
#ifdef _WIN32
#include < winsock2.h >
#include < io.h >
#include < Ws2tcpip.h >
#pragma comment(lib, "ws2_32.lib")
#else
#include < sys / types.h >
#include < sys / socket.h >
#include < netinet / in .h >
#include < arpa / inet.h >
#include < unistd.h >
#include < errno.h >
#define closesocket close
#endif
#define BUF_SIZE 0x1000
char * host_name = " 224.1.1.3 " ;
int port = 12345 ;
int main( int argc, char * argv[])
{
int loop = 1 ;
/* 多播循环 */
int iter = 0 ;
int from_len;
char buffer[BUF_SIZE];
int socket_descriptor;
struct ip_mreq command;
struct sockaddr_in loc;
struct sockaddr_in rem;
int rec_len = 0 ;
int ptr_point = 0 ;
size_t bytes_written = 0 ;
int loop_times = 0 ;
int rcv_port_0 = 0 ;
int rcv_port_1 = 0 ;
int first = 0 ;
#ifdef _WIN32
WSADATA wsaData;
if ( WSAStartup(MAKEWORD( 2 , 2 ), & wsaData) != 0 )
{
printf( " Error in WSAStartup/n " );
exit( 1 );
}
#endif
if (argv[ 1 ])
{
host_name = argv[ 1 ];
printf( " %s /n " , host_name);
}
if (argv[ 2 ])
{
port = atoi(argv[ 2 ]);
printf( " %d /n " , port);
}
memset( & loc, 0 , sizeof (loc));
loc.sin_family = AF_INET;
//这个地方很重要，不然linux下就只能是broadcast；所以必须指定组播的地址；
loc.sin_port = htons(port);
loc.sin_addr.s_addr = inet_addr(host_name);
if ((socket_descriptor = socket(AF_INET, SOCK_DGRAM, 0 )) == - 1 )
{
perror( " socket " );
exit(EXIT_FAILURE);
}
/* can use the same port in the pc */
loop = 1 ;
if (setsockopt(socket_descriptor, SOL_SOCKET, SO_REUSEADDR, & loop, sizeof (loop)) < 0 )
{
perror( " setsockopt:SO_REUSEADDR./n " );
exit(EXIT_FAILURE);
} else
{
printf( " setsockopt:SO_REUSEADDR./n " );
}
loop = 0x1000000 ;// 设置网络的接收buffer的大小
if ( setsockopt( socket_descriptor, SOL_SOCKET, SO_RCVBUF, ( void * ) & loop, sizeof ( loop ) ) < 0 )
{
perror( " setsockopt:SO_RCVBUF./n " );
exit(EXIT_FAILURE);
}
//由于在前面指定了组播的地址，但是在winodws和linux下不一样，就得这么处理，这个细节来之分析VLC源代码/*
#if defined( WIN32 ) || defined( UNDER_CE )
* Under Win32 and for multicasting, we bind to INADDR_ANY.
* This is of course a severe bug, since the socket would logically
* receive unicast traffic, and multicast traffic of groups subscribed
* to via other sockets. How this actually works in Winsock, I don't
* know.
*/
if ( IN_MULTICAST( ntohl( loc.sin_addr.s_addr ) ) )
{
struct sockaddr_in stupid = loc;
stupid.sin_addr.s_addr = INADDR_ANY;
if ( bind( socket_descriptor, ( struct sockaddr * ) & stupid, sizeof ( stupid ) ) < 0 )
{
perror( " bind socket./n " );
close( socket_descriptor );
return 0 ;
}
}
else
#endif
if (bind(socket_descriptor, ( struct sockaddr * ) & loc, sizeof (loc)) < 0 )
{
perror( " bind socket./n " );
exit(EXIT_FAILURE);
}
{ //加入组播组，如果有多块网卡，可以用另一个变量来特别设置；
printf( " %s,%d/n " , host_name, port);
command.imr_multiaddr.s_addr = inet_addr(host_name);
command.imr_interface.s_addr = htonl(INADDR_ANY);
if (command.imr_multiaddr.s_addr == - 1 )
{
perror( " 224.1.1.3 not a legal multicast address./n " );
exit(EXIT_FAILURE);
}
if (setsockopt(socket_descriptor, IPPROTO_IP, IP_ADD_MEMBERSHIP, & command, sizeof (command)) < 0 )
{
perror( " setsockopt:IP_ADD_MEMBERSHIP. error/n " );
}
}
printf( " start reciving.../n " );
from_len = sizeof (rem);
while ( 1 )
{
memset( & rem, 0 , from_len);
memset(buffer, 0 , BUF_SIZE);
if ( (rec_len = recvfrom(socket_descriptor, buffer, sizeof ( char ) * BUF_SIZE, 0 , ( struct sockaddr * ) & rem, & from_len)) == - 1 ) {
perror( " recvfrom./n " );
}
printf( " From host:%s port:%d, len: %d/n " , inet_ntoa(rem.sin_addr), ntohs(rem.sin_port), rec_len);
}
if (setsockopt(socket_descriptor, IPPROTO_IP, IP_DROP_MEMBERSHIP, & command, sizeof (command)) < 0 ) {
perror( " setsockopt:IP_DROP_MEMBERSHIP./n " );
}
closesocket(socket_descriptor);
exit(EXIT_SUCCESS);
}
1.在windows中不需要特殊的设置网络；
2.在Linux下得特别注意网络的设置，有下面几个环节：
1）查看内核模块，是否已经加载了multicast支持；这个可以通过 在src目录下面 make menuconfig 查看ip 设置栏目看到；
2）查看网络是否已经加载了multicast支持；命令：ip a 可以看到现在网络支持的各个功能；
3）添加multicast 网络路由：net add -net 224.0.0.0 netmask 240.0.0.0 dev eth0
这样才能启动网络的multicast路由支持，不然只能当作broadcast处理。