c-在Linux上侦听IPv6多播

我正在尝试获取一个简单的多播示例以在Linux上工作(我已经
尝试了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,然后添加
本身属于组ff02 :: 1.然后,我希望它收到
多播发送到ff02 :: 1.以下代码可在Mac OS X 10.5(适用于
实际上,在OS X上运行的服务器会从Linux发送多播
客户),但我无法使Linux服务器端正常工作.不会
获得任何多播.如果我更改代码以绑定到::(INADDR6_ANY)
而不是单播地址(我尝试了本地链接和全局链接
地址),它确实获得了多播.我想知道是否有人
可以指出我做错了什么.

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 );

解决方法:

绑定会过滤传入的地址,因此,如果绑定到适配器地址,则仅会收到与目标地址匹配的数据包：即单播数据包,如果绑定到多播地址,则只会获取多播数据包；要获取多播和单播数据包,您必须绑定到INADDR_ANY或IN6ADDR_ANY.

标签：ipv6,linux,c-4,multicast
来源： https://codeday.me/bug/20191209/2096332.html