在Linux上监听IPv6多播消息

Question

在Linux上监听IPv6多播消息

4

我正在尝试在Linux上实现一个简单的组播示例（我尝试过RHEL 4 2.6.9和Ubuntu 8.04 2.6.24）。总体思路是，我希望服务器绑定到单播地址，然后将自己添加到组ff02::1中。然后，我希望它能接收发送到ff02::1的多播消息。下面的代码在Mac OS X 10.5上运行良好（事实上，运行在OS X上的服务器可以接收来自Linux客户端的多播消息），但我无法让Linux服务器端正常工作。它没有接收到任何多播消息。如果我将代码更改为绑定到::（INADDR6_ANY）而不是单播地址（我尝试过链路本地和全局地址），它就可以接收到多播消息。我想知道我做错了什么，请指点一下。

服务器：

memset( &hint, 0, sizeof( hint ) );

hint.ai_family = AF_INET6;
hint.ai_socktype = SOCK_DGRAM;

// argv[1] is either a link-local or a global address
err = getaddrinfo( argv[1], NULL, &hint, &info );

if( err != 0 ) {
    perror( "getaddrinfo" );
    exit( 1 );
}

struct sockaddr_in6 * addr = (struct sockaddr_in6*)info->ai_addr;
//addr->sin6_addr = in6addr_any; // if this is uncommented, multicasts are received
addr->sin6_port = htons( 7890 );
s = socket( AF_INET6, SOCK_DGRAM, 0 );

if( bind( s, (struct sockaddr*) addr, info->ai_addrlen ) != 0 ) {
    close( s );
    perror( "bind" );
    exit( 1 );
}

if( getaddrinfo( "ff02::1", NULL, &hint, &multi ) != 0 ) {
    close( s );
    perror( "getaddrinfo" );
    exit( 1 );
}

struct ipv6_mreq mreq;
memset( &mreq, 0, sizeof(mreq) );
memcpy( &mreq.ipv6mr_multiaddr, &((struct sockaddr_in6 *) multi->ai_addr)->sin6_addr, sizeof(mreq.ipv6mr_multiaddr) );
mreq.ipv6mr_interface = 2; // 2 happens to be the interface ID; I've tried other values here
freeaddrinfo( multi );

if( setsockopt( s, IPPROTO_IPV6, IPV6_JOIN_GROUP, &mreq, sizeof(mreq) ) != 0 ) {
    close( s );
    perror( "IPV6_JOIN_GROUP" );
    exit( 1 );
}

for( ; ; ) {
    char data[6];
    size_t len;

    len = recvfrom( s, data, 5, 0, NULL, NULL );
    data[5] = '\0';

    printf( "Received %s\n", data );

    if( strcmp( data, "exitt" ) == 0 ) {
        break;
    }
}

客户端代码如下：

memset( &hint, 0, sizeof( hint ) );

hint.ai_family = AF_INET6;
hint.ai_socktype = SOCK_DGRAM;
hint.ai_protocol = 0;

err = getaddrinfo( "ff02::1", NULL, &hint, &info );

if( err != 0 ) {
    perror( "getaddrinfo" );
    return 0;
}

struct sockaddr_in6 * addr = (struct sockaddr_in6*)info->ai_addr;
addr->sin6_port = htons( 7890 );
addr->sin6_scope_id = 2; // 2 happens to be the interface ID
s = socket( AF_INET6, SOCK_DGRAM, 0 );

for( ; ; ) {
    char data[6];
    size_t len;

    scanf( "%5s", data );
    data[5] = '\0';
    printf( "Sending %s\n", data );
    if( sendto( s, data, 5, 0, info->ai_addr, info->ai_addrlen ) != 5 ) {
        printf( "Error sending\n" );
    }

    if( strcmp( data, "exitt" ) == 0 ) {
        break;
    }
}

close( s );

- Ray

1个回答

网页内容由stack overflow 提供, 点击上面的

可以查看英文原文，
原文链接

- Steve-o · Accepted Answer

绑定过滤器会将传入的地址与绑定的适配器地址进行匹配，这样就只会接收到目标地址匹配的分组，也就是单播分组；如果绑定到多播地址，则只会接收到多播分组；如果需要同时接收多播和单播分组，必须绑定到 INADDR_ANY 或 IN6ADDR_ANY。