[BusyBox] tftp: bind with no sin_family

[Shaun Jackman]

These two lines from tftp.c have me a little confused:
        memset(&sa, 0, len);
        bind(socketfd, (struct sockaddr *)&sa, len);
With no sin_family value set, does this call mean anything to the
kernel? The call succeeds under Linux at least, but I have no idea
what effect the call has.

Could these lines be removed with no ill effect? Do they perhaps have
the same semantics as the following:
        memset(&sa, 0, len);
        sa.sin_family = AF_INET;
        sa.sin_addr.s_addr = INADDR_ANY;
        bind(socketfd, (struct sockaddr *)&sa, len);
If so, is the kernel inferring the sin_family type from the domain of
the socket file descriptor?

This is mostly for my own curiosity. I really expected the bind call
to fail and was rather surprised when I saw that it didn't. I'd
appreciate someone putting my mind to rest.

Cheers,
Shaun