From: Xufeng Zhang <xufeng.zh...@windriver.com>
Date: Fri, 9 May 2014 13:47:35 +0800
> Current implementation for pfkey_sendmsg() always return success
> no matter whether or not error happens during this syscall,
> this is incompatible with the general send()/sendmsg() API:
> man send
> RETURN VALUE
> On success, these calls return the number of characters sent.
> On error, -1 is returned, and errno is set appropriately.
>
> One side effect this problem introduces is that we can't determine
> when to resend the message when the previous send() fails because
> it was interrupted by signals.
> We detect such a problem when racoon is sending SADBADD message to
> add SAD entry in the kernel, but sometimes kernel is responding with
> "Interrupted system call"(-EINTR) error.
>
> Check the send implementation of strongswan, it has below logic:
> pfkey_send_socket()
> {
> ...
> while (TRUE)
> {
> len = send(socket, in, in_len, 0);
>
> if (len != in_len)
> {
> case EINTR:
> /* interrupted, try again */
> continue;
> ...
> }
> }
> ...
> }
> So it makes sense to return errors for send() syscall.
>
> Signed-off-by: Xufeng Zhang <xufeng.zh...@windriver.com>
I disagree.
If pfkey_error() is successful, the error will be reported in the AF_KEY
message that is broadcast, there is no reason for sendmsg to return an
error. The message was sucessfully sent, there was no problem with it's
passage into the AF_KEY layer.
Like netlink, operational responses come in packets, not error codes.
However, if pfkey_error() fails, we must do pass back the original
error code because it's a last ditch effort to prevent information
from being lost.
That's why 'err' must be preserved when pfkey_error() returns zero.
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