selftests/net: SO_TXTIME with ETF and FQ

The SO_TXTIME API enables packet tranmission with delayed delivery.
This is currently supported by the ETF and FQ packet schedulers.

Evaluate the interface with both schedulers. Install the scheduler
and send a variety of packets streams: without delay, with one
delayed packet, with multiple ordered delays and with reordering.
Verify that packets are released by the scheduler in expected order.

The ETF qdisc requires a timestamp in the future on every packet. It
needs a delay on the qdisc else the packet is dropped on dequeue for
having a delivery time in the past. The test value is experimentally
derived. ETF requires clock_id CLOCK_TAI. It checks this base and
drops for non-conformance.

The FQ qdisc expects clock_id CLOCK_MONOTONIC, the base used by TCP
as of commit fb420d5d91c1 ("tcp/fq: move back to CLOCK_MONOTONIC").
Within a flow there is an expecation of ordered delivery, as shown by
delivery times of test 4. The FQ qdisc does not require all packets to
have timestamps and does not drop for non-conformance.

The large (msec) delays are chosen to avoid flakiness.

	Output:

	SO_TXTIME ipv6 clock monotonic
	payload:a delay:28 expected:0 (us)

	SO_TXTIME ipv4 clock monotonic
	payload:a delay:38 expected:0 (us)

	SO_TXTIME ipv6 clock monotonic
	payload:a delay:40 expected:0 (us)

	SO_TXTIME ipv4 clock monotonic
	payload:a delay:33 expected:0 (us)

	SO_TXTIME ipv6 clock monotonic
	payload:a delay:10120 expected:10000 (us)

	SO_TXTIME ipv4 clock monotonic
	payload:a delay:10102 expected:10000 (us)

	[.. etc ..]

	OK. All tests passed

Changes v1->v2: update commit message output

Signed-off-by: Willem de Bruijn <willemb@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Acked-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 296 insertions, 0 deletions

diff --git a/tools/testing/selftests/net/so_txtime.c b/tools/testing/selftests/net/so_txtime.c
new file mode 100644
index 000000000000..53f598f06647
--- /dev/null
+++ b/tools/testing/selftests/net/so_txtime.c
@@ -0,0 +1,296 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Test the SO_TXTIME API
+ *
+ * Takes two streams of { payload, delivery time }[], one input and one output.
+ * Sends the input stream and verifies arrival matches the output stream.
+ * The two streams can differ due to out-of-order delivery and drops.
+ */
+
+#define _GNU_SOURCE
+
+#include <arpa/inet.h>
+#include <error.h>
+#include <errno.h>
+#include <linux/net_tstamp.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <time.h>
+#include <unistd.h>
+
+static int	cfg_clockid	= CLOCK_TAI;
+static bool	cfg_do_ipv4;
+static bool	cfg_do_ipv6;
+static uint16_t	cfg_port	= 8000;
+static int	cfg_variance_us	= 2000;
+
+static uint64_t glob_tstart;
+
+/* encode one timed transmission (of a 1B payload) */
+struct timed_send {
+	char	data;
+	int64_t	delay_us;
+};
+
+#define MAX_NUM_PKT	8
+static struct timed_send cfg_in[MAX_NUM_PKT];
+static struct timed_send cfg_out[MAX_NUM_PKT];
+static int cfg_num_pkt;
+
+static uint64_t gettime_ns(void)
+{
+	struct timespec ts;
+
+	if (clock_gettime(cfg_clockid, &ts))
+		error(1, errno, "gettime");
+
+	return ts.tv_sec * (1000ULL * 1000 * 1000) + ts.tv_nsec;
+}
+
+static void do_send_one(int fdt, struct timed_send *ts)
+{
+	char control[CMSG_SPACE(sizeof(uint64_t))];
+	struct msghdr msg = {0};
+	struct iovec iov = {0};
+	struct cmsghdr *cm;
+	uint64_t tdeliver;
+	int ret;
+
+	iov.iov_base = &ts->data;
+	iov.iov_len = 1;
+
+	msg.msg_iov = &iov;
+	msg.msg_iovlen = 1;
+
+	if (ts->delay_us >= 0) {
+		memset(control, 0, sizeof(control));
+		msg.msg_control = &control;
+		msg.msg_controllen = sizeof(control);
+
+		tdeliver = glob_tstart + ts->delay_us * 1000;
+
+		cm = CMSG_FIRSTHDR(&msg);
+		cm->cmsg_level = SOL_SOCKET;
+		cm->cmsg_type = SCM_TXTIME;
+		cm->cmsg_len = CMSG_LEN(sizeof(tdeliver));
+		memcpy(CMSG_DATA(cm), &tdeliver, sizeof(tdeliver));
+	}
+
+	ret = sendmsg(fdt, &msg, 0);
+	if (ret == -1)
+		error(1, errno, "write");
+	if (ret == 0)
+		error(1, 0, "write: 0B");
+
+}
+
+static void do_recv_one(int fdr, struct timed_send *ts)
+{
+	int64_t tstop, texpect;
+	char rbuf[2];
+	int ret;
+
+	ret = recv(fdr, rbuf, sizeof(rbuf), 0);
+	if (ret == -1)
+		error(1, errno, "read");
+	if (ret != 1)
+		error(1, 0, "read: %dB", ret);
+
+	tstop = (gettime_ns() - glob_tstart) / 1000;
+	texpect = ts->delay_us >= 0 ? ts->delay_us : 0;
+
+	fprintf(stderr, "payload:%c delay:%ld expected:%ld (us)\n",
+			rbuf[0], tstop, texpect);
+
+	if (rbuf[0] != ts->data)
+		error(1, 0, "payload mismatch. expected %c", ts->data);
+
+	if (labs(tstop - texpect) > cfg_variance_us)
+		error(1, 0, "exceeds variance (%d us)", cfg_variance_us);
+}
+
+static void do_recv_verify_empty(int fdr)
+{
+	char rbuf[1];
+	int ret;
+
+	ret = recv(fdr, rbuf, sizeof(rbuf), 0);
+	if (ret != -1 || errno != EAGAIN)
+		error(1, 0, "recv: not empty as expected (%d, %d)", ret, errno);
+}
+
+static void setsockopt_txtime(int fd)
+{
+	struct sock_txtime so_txtime_val = { .clockid = cfg_clockid };
+	struct sock_txtime so_txtime_val_read = { 0 };
+	socklen_t vallen = sizeof(so_txtime_val);
+
+	if (setsockopt(fd, SOL_SOCKET, SO_TXTIME,
+		       &so_txtime_val, sizeof(so_txtime_val)))
+		error(1, errno, "setsockopt txtime");
+
+	if (getsockopt(fd, SOL_SOCKET, SO_TXTIME,
+		       &so_txtime_val_read, &vallen))
+		error(1, errno, "getsockopt txtime");
+
+	if (vallen != sizeof(so_txtime_val) ||
+	    memcmp(&so_txtime_val, &so_txtime_val_read, vallen))
+		error(1, 0, "getsockopt txtime: mismatch");
+}
+
+static int setup_tx(struct sockaddr *addr, socklen_t alen)
+{
+	int fd;
+
+	fd = socket(addr->sa_family, SOCK_DGRAM, 0);
+	if (fd == -1)
+		error(1, errno, "socket t");
+
+	if (connect(fd, addr, alen))
+		error(1, errno, "connect");
+
+	setsockopt_txtime(fd);
+
+	return fd;
+}
+
+static int setup_rx(struct sockaddr *addr, socklen_t alen)
+{
+	struct timeval tv = { .tv_usec = 100 * 1000 };
+	int fd;
+
+	fd = socket(addr->sa_family, SOCK_DGRAM, 0);
+	if (fd == -1)
+		error(1, errno, "socket r");
+
+	if (bind(fd, addr, alen))
+		error(1, errno, "bind");
+
+	if (setsockopt(fd, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv)))
+		error(1, errno, "setsockopt rcv timeout");
+
+	return fd;
+}
+
+static void do_test(struct sockaddr *addr, socklen_t alen)
+{
+	int fdt, fdr, i;
+
+	fprintf(stderr, "\nSO_TXTIME ipv%c clock %s\n",
+			addr->sa_family == PF_INET ? '4' : '6',
+			cfg_clockid == CLOCK_TAI ? "tai" : "monotonic");
+
+	fdt = setup_tx(addr, alen);
+	fdr = setup_rx(addr, alen);
+
+	glob_tstart = gettime_ns();
+
+	for (i = 0; i < cfg_num_pkt; i++)
+		do_send_one(fdt, &cfg_in[i]);
+	for (i = 0; i < cfg_num_pkt; i++)
+		do_recv_one(fdr, &cfg_out[i]);
+
+	do_recv_verify_empty(fdr);
+
+	if (close(fdr))
+		error(1, errno, "close r");
+	if (close(fdt))
+		error(1, errno, "close t");
+}
+
+static int parse_io(const char *optarg, struct timed_send *array)
+{
+	char *arg, *tok;
+	int aoff = 0;
+
+	arg = strdup(optarg);
+	if (!arg)
+		error(1, errno, "strdup");
+
+	while ((tok = strtok(arg, ","))) {
+		arg = NULL;	/* only pass non-zero on first call */
+
+		if (aoff / 2 == MAX_NUM_PKT)
+			error(1, 0, "exceeds max pkt count (%d)", MAX_NUM_PKT);
+
+		if (aoff & 1) {	/* parse delay */
+			array->delay_us = strtol(tok, NULL, 0) * 1000;
+			array++;
+		} else {	/* parse character */
+			array->data = tok[0];
+		}
+
+		aoff++;
+	}
+
+	free(arg);
+
+	return aoff / 2;
+}
+
+static void parse_opts(int argc, char **argv)
+{
+	int c, ilen, olen;
+
+	while ((c = getopt(argc, argv, "46c:")) != -1) {
+		switch (c) {
+		case '4':
+			cfg_do_ipv4 = true;
+			break;
+		case '6':
+			cfg_do_ipv6 = true;
+			break;
+		case 'c':
+			if (!strcmp(optarg, "tai"))
+				cfg_clockid = CLOCK_TAI;
+			else if (!strcmp(optarg, "monotonic") ||
+				 !strcmp(optarg, "mono"))
+				cfg_clockid = CLOCK_MONOTONIC;
+			else
+				error(1, 0, "unknown clock id %s", optarg);
+			break;
+		default:
+			error(1, 0, "parse error at %d", optind);
+		}
+	}
+
+	if (argc - optind != 2)
+		error(1, 0, "Usage: %s [-46] -c <clock> <in> <out>", argv[0]);
+
+	ilen = parse_io(argv[optind], cfg_in);
+	olen = parse_io(argv[optind + 1], cfg_out);
+	if (ilen != olen)
+		error(1, 0, "i/o streams len mismatch (%d, %d)\n", ilen, olen);
+	cfg_num_pkt = ilen;
+}
+
+int main(int argc, char **argv)
+{
+	parse_opts(argc, argv);
+
+	if (cfg_do_ipv6) {
+		struct sockaddr_in6 addr6 = {0};
+
+		addr6.sin6_family = AF_INET6;
+		addr6.sin6_port = htons(cfg_port);
+		addr6.sin6_addr = in6addr_loopback;
+		do_test((void *)&addr6, sizeof(addr6));
+	}
+
+	if (cfg_do_ipv4) {
+		struct sockaddr_in addr4 = {0};
+
+		addr4.sin_family = AF_INET;
+		addr4.sin_port = htons(cfg_port);
+		addr4.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
+		do_test((void *)&addr4, sizeof(addr4));
+	}
+
+	return 0;
+}