arguments to sockaddr_equal (sockaddr vs sockaddr_storage)?

Jelmer Vernooij jelmer at
Sun Apr 5 12:53:35 GMT 2009

Hi Volker,

Volker Lendecke wrote:
> In master right now the function sockaddr_equal takes to
> const struct sockaddr *. In 3.3, it takes const struct
> sockaddr_storage.
> Didn't Jeremy go through big pain introducing
> sockaddr_storage when putting in IPv6 support? Why did we go
> to struct sockaddr again?
> I must have understood something wrong, can someone help me?
We used to use "struct sockaddr_in", not "struct sockaddr". The first is
specific to IPv4, "struct sockaddr" is a generic pointer for socket

"struct sockaddr" is only has a sa_family member that can be used to see
what it actually contains, so it can be casted (as is done in the socket
code) to (struct sockaddr_in, sockaddr_in6, sockaddr_un, etc). It is the
argument received e.g. by connect().

The main difference between "struct sockaddr" and "struct
sockaddr_storage" is that the latter is guaranteed to be big enough to
hold a ipv6 or a ipv4 address. Since not all of these functions rely on
the argument being passed being at least the size of "struct
sockaddr_storage", this distinction is useful since Samba 4 can use the
functions that take a "struct sockaddr" with "struct sockaddr_in"
structures but can't use the functions that take a "sockaddr_storage"



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