OSX上的UDP广播失败，但在Linux上工作

发布于 2025-02-07 16:58:54 字数 1149 浏览 1 评论 0原文

以下代码在OSX上不起作用（在Linux上可以正常工作）；它（绑定）失败，errno = 49 无法分配请求的地址。

    int fd, val;
    struct sockaddr_in sa;

    fd = socket(AF_INET, SOCK_DGRAM, 0);
    if(fd < 0)
        return -1;
    
    val = 1;
    if(setsockopt(fd, SOL_SOCKET, SO_BROADCAST, &val, sizeof(val)) < 0)
        goto exit;

    memset(&sa, 0, sizeof(sa));
    sa.sin_len = sizeof(sa);
    sa.sin_family = AF_INET;
    sa.sin_addr.s_addr = htonl(INADDR_BROADCAST);
    sa.sin_port = htons(50000);

    if(bind(fd, (struct sockaddr *)&sa, sizeof(sa)))
        goto exit;

如果您指定了inaddr_broadcast（或者，至少inaddr_any工作正常），则该代码确实可以在OSX上使用。我发现Darwin具有Linux没有的sin_len字段，但是设置或清除它没有效果。

知道有什么麻烦？如果它与MACF有关，我觉得它似乎会返回与安全有关的错误。

总体而言，很少有OSX的示例来源，我找不到UDP广播的任何示例。

似乎甚至socat无法在OSX上正确执行此操作。顺便说一句，它以相同的方式失败，同样的错误。

$ echo "TEST" | socat - UDP-DATAGRAM:255.255.255.255:50000,broadcast
2022/06/13 22:39:16 socat[7349] E sendto(5, 0x14100c000, 17, 0, LEN=16 AF=2 255.255.255.255: 50000, 16): Can't assign requested address

原文

The following code does not work on OSX (it works fine on Linux); it (bind) fails with errno=49 Can't assign requested address.

    int fd, val;
    struct sockaddr_in sa;

    fd = socket(AF_INET, SOCK_DGRAM, 0);
    if(fd < 0)
        return -1;
    
    val = 1;
    if(setsockopt(fd, SOL_SOCKET, SO_BROADCAST, &val, sizeof(val)) < 0)
        goto exit;

    memset(&sa, 0, sizeof(sa));
    sa.sin_len = sizeof(sa);
    sa.sin_family = AF_INET;
    sa.sin_addr.s_addr = htonl(INADDR_BROADCAST);
    sa.sin_port = htons(50000);

    if(bind(fd, (struct sockaddr *)&sa, sizeof(sa)))
        goto exit;

This bit of code does work on OSX if you specify an actual address other than INADDR_BROADCAST (or, at least INADDR_ANY works fine). I found that Darwin has this sin_len field that Linux does not, but setting or leaving it cleared has no effect.

Any idea what could be the trouble? If it were related to MACF I feel as if it would return a security-related error.

There are few example sources for OSX in general, and I did not find any for UDP broadcast.

It seems even socat can't do this properly on OSX. Incidentally it failed in the same way with the same error.

$ echo "TEST" | socat - UDP-DATAGRAM:255.255.255.255:50000,broadcast
2022/06/13 22:39:16 socat[7349] E sendto(5, 0x14100c000, 17, 0, LEN=16 AF=2 255.255.255.255: 50000, 16): Can't assign requested address

分享到QQ

分享到微博