Re: [PATCH bpf-next v2 5/9] selftests/bpf: Add selftest for sockmap/hashmap redirection

[Jiayuan Chen]

On Fri, Apr 11, 2025 at 01:32:41PM +0200, Michal Luczaj wrote:
> +static void test_send_redir_recv(int sd_send, int send_flags, int sd_peer,
> +				 int sd_in, int sd_out, int sd_recv,
> +				 struct maps *maps, int status)
> +{
> +	unsigned int drop, pass;
> +	char *send_buf = "ab";
> +	char recv_buf = '\0';
> +	ssize_t n, len = 1;
> +	/* Zero out the verdict map */
> +	if (xbpf_map_update_elem(maps->verd, &u32(SK_DROP), &u32(0), BPF_ANY) ||
> +	    xbpf_map_update_elem(maps->verd, &u32(SK_PASS), &u32(0), BPF_ANY))
> +		return;
> +
> +	if (xbpf_map_update_elem(maps->in, &u32(0), &u64(sd_in), BPF_NOEXIST))
> +		return;
> +
> +	if (xbpf_map_update_elem(maps->out, &u32(0), &u64(sd_out), BPF_NOEXIST))
> +		goto del_in;
> +
> +	/* Last byte is OOB data when send_flags has MSG_OOB bit set */
> +	if (send_flags & MSG_OOB)
> +		len++;
> +	n = send(sd_send, send_buf, len, send_flags);
> +	if (n >= 0 && n < len)
> +		FAIL("incomplete send");
> +	if (n < 0) {
> +		/* sk_msg redirect combo not supported? */
> +		if (status & SUPPORTED || errno != EACCES)
> +			FAIL_ERRNO("send");
> +		goto out;
> +	}
> +
> +	if (!(status & SUPPORTED)) {
> +		handle_unsupported(sd_send, sd_peer, sd_in, sd_out, sd_recv,
> +				   maps->verd, status);
> +		goto out;
> +	}
> +
> +	errno = 0;
> +	n = recv_timeout(sd_recv, &recv_buf, 1, 0, IO_TIMEOUT_SEC);
> +	if (n != 1) {
> +		FAIL_ERRNO("recv_timeout()");
> +		goto out;
> +	}
I prefer multiple send and receive operations, or implementing a loop at
the outer level.

Thanks.