[Bug 1001656] FreeBSD: add AF_PACKET socket familiy

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http://bugs.ecos.sourceware.org/show_bug.cgi?id=1001656

--- Comment #6 from Bernd Edlinger <bernd.edlinger@hotmail.de> ---
(In reply to comment #5)
Hi Jürgen,

> Because I am porting the busybox dhcp server to eCos, I am using your raw
> packet patch.
> When I do 'man 7 packet' on my linux, I get a slightly different definition
> of 'struct sockaddr_ll' (as also used by busybox): I have 'int sll_ifindex;'
> instead of 'u_short sll_index;' and 'unsigned char sll_addr[8];' instead of
> 'u_char sll_addr[22];'.
> I guess the naming difference is because your code is based on the freeBSD,
> and the busybox is based on Linux.
> But why 22 bytes for the address ('ssl_addr'), you only use 6B of it
> (EHTER_ADDR_LEN)?

good questions...

1. actually the name should be sll_ifindex. I somehow missed that typo.

2. the data type that is used by the bsd stack to index the interfaces
   is u_short, therefore I thought it would be better to use that instead.
   Same for the SIOCGIFINDEX ioctl, which uses only u_short.

3. in linux sizeof (struct sockaddr_ll) = 20 which is larger than
   sizeof(struct sockaddr) = 16.
   But on eCos the sockaddr is 32 bytes. Therefore the sockaddr_ll
   must be at least 32 bytes. Therefore I enlarged the sll_addr to 22.

Note: All socket addressses should be exactly 32 bytes in eCos,
because of this code in ./io/fileio/current/src/socket.cxx:

__externC int   bind (int s, const struct sockaddr *sa, unsigned int len)
{
...
    struct sockaddr sa2 = *sa;



regading 1, I will change the name.

regarding 2, I could change the type to int, and cast it
to u_short later, but only if that improves protability.

Is it your impression that this change would improve the
portability of the busybox dhcp server?

regarding 3, the sizeof sll_addr should be irrelevant to
the application as only 6 bytes are really used.

Does the existion code use the size of the sll_addr array
for anything? Does it break unless this array is exactly 8 bytes?


Regards
Bernd.

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