WSAEFAULT error when use getsockname function

Question

I have a problem using getsockname function. I have this code:

struct sockaddr sa;
int sa_len;
sa_len = sizeof(sa);
if (getsockname(socketfd, &sa, &sa_len) != SOCKET_ERROR)
{
   ///
}
else
{
   int error = WSAGetLastError();
   //error here WSAEFAULT always
}

As you can see, i always have error when use getsockname function. Error - WSAEFAULT. But why? structure and structure size are right, why this happens?

WSAEFAULT desc:

The name or the namelen parameter is not a valid part of the user address space, or the namelen parameter is too small.

p.s. Application is 64 bit

Thanks!

Hasturkun · Accepted Answer · 2013-01-31T11:32:57.423

4

Your struct sockaddr is too small to accept the socket address. Either use an appropriately sized struct, such as struct sockaddr_in, or better yet, use a struct sockaddr_storage, which is guaranteed to be large enough to contain the address. Using a sockaddr_storage also allows you to easily support both IPv4 and IPv6 with minimal adjustments.

Edited code:

struct sockaddr_storage sa;
int sa_len;
sa_len = sizeof(sa);
if (getsockname(socketfd, (struct sockaddr *)&sa, &sa_len) != SOCKET_ERROR)

edited Jan 31 '13 at 11:32

answered Jan 31 '13 at 11:26

Hasturkun

35,395
6
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104

Thanks for your answer! But how to get port from `sockaddr_storage`? I don't see `sin_port` value – Breakdown Jan 31 '13 at 11:37
2

That's easy. You check `sa->ss_family`, and then cast it to the appropriate type, ie. cast to `struct sockaddr_in` for `AF_INET`, and `struct sockaddr_in6` for `AF_INET6` – Hasturkun Jan 31 '13 at 11:41
Oh, also, if you want the port for display purposes, you can use `getnameinfo()` to return both the address and the port, all without fiddling with IPv4 and IPv6 specifics. – Hasturkun Jan 31 '13 at 12:47

score 1 · Answer 2 · answered Jan 31 '13 at 11:27

1

Instead of general struct sockaddr use the one specified for your protocol i.e. *struct sockaddr_in* for IPv4 address. See here for a complete example.

answered Jan 31 '13 at 11:27

KBart

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WSAEFAULT error when use getsockname function

2 Answers2