[PATCH net 4/4] selftests: net: add SCTP I-FORWARD-TSN tests with message interleaving

[Tim Budding <tim.budding@gmail.com>]

Add tests for the receiver side of I-FORWARD-TSN with user message
interleaving (RFC 8260) and partial reliability. The first four tests
interleave a 64KB reliable message on stream 0 with a PR-SCTP message on
stream 1, which an nft rule drops so that the sender abandons it. The
tests are:

- ordered, unordered: the large message, ordered and unordered, must be
  delivered intact, and the abandoned message's received fragments must
  be freed.
- leading_edge: with the large message in partial delivery, drop all
  data after the abandoned message until the I-FORWARD-TSN arrives; this
  must not be treated as an association reset.
- uo_pd: abandon an unordered message during its partial delivery; the
  partial delivery must be aborted and the next unordered message on the
  stream must be delivered on its own.
- reset: an SSN/TSN association reset with interleaving completes and
  leaves a working association.

The PR-SCTP message is abandoned after one retransmission (RTX policy),
which keeps the tests stable on slow or loaded machines.

Signed-off-by: Tim Budding <tim.budding@gmail.com>
---
 tools/testing/selftests/net/.gitignore      |   1 +
 tools/testing/selftests/net/Makefile        |   2 +
 tools/testing/selftests/net/sctp_ifwdtsn.c  | 538 ++++++++++++++++++++
 tools/testing/selftests/net/sctp_ifwdtsn.sh | 141 +++++
 4 files changed, 682 insertions(+)
 create mode 100644 tools/testing/selftests/net/sctp_ifwdtsn.c
 create mode 100755 tools/testing/selftests/net/sctp_ifwdtsn.sh

diff --git a/tools/testing/selftests/net/.gitignore b/tools/testing/selftests/net/.gitignore
index 21412510ac26..ca451bfeda75 100644
--- a/tools/testing/selftests/net/.gitignore
+++ b/tools/testing/selftests/net/.gitignore
@@ -34,6 +34,7 @@ reuseport_bpf_numa
 reuseport_dualstack
 rxtimestamp
 sctp_hello
+sctp_ifwdtsn
 sk_bind_sendto_listen
 sk_connect_zero_addr
 sk_so_peek_off
diff --git a/tools/testing/selftests/net/Makefile b/tools/testing/selftests/net/Makefile
index df215e1a6262..58ca9fc23979 100644
--- a/tools/testing/selftests/net/Makefile
+++ b/tools/testing/selftests/net/Makefile
@@ -90,6 +90,7 @@ TEST_PROGS := \
 	run_afpackettests \
 	run_netsocktests \
 	rxtimestamp.sh \
+	sctp_ifwdtsn.sh \
 	sctp_vrf.sh \
 	skf_net_off.sh \
 	srv6_encap_lookup_l3vpn_test.sh \
@@ -164,6 +165,7 @@ TEST_GEN_FILES := \
 	reuseport_addr_any \
 	rxtimestamp \
 	sctp_hello \
+	sctp_ifwdtsn \
 	skf_net_off \
 	so_netns_cookie \
 	so_rcv_listener \
diff --git a/tools/testing/selftests/net/sctp_ifwdtsn.c b/tools/testing/selftests/net/sctp_ifwdtsn.c
new file mode 100644
index 000000000000..15346aca10ef
--- /dev/null
+++ b/tools/testing/selftests/net/sctp_ifwdtsn.c
@@ -0,0 +1,538 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Helper for sctp_ifwdtsn.sh: I-FORWARD-TSN handling with SCTP user message
+ * interleaving (RFC 8260) and partial reliability (RFC 3758).
+ *
+ * Runs both endpoints of one association: the server socket is created in
+ * the current network namespace, the client socket in the namespace given
+ * on the command line. The caller sets up the link and any nft rule that
+ * drops chunks. Messages sent by the client:
+ *
+ *   big:    64KB on stream 0, reliable, fragmented into ~66 I-DATA chunks
+ *   small:  on stream 1, PR-SCTP "RTX" policy allowing one retransmission;
+ *           the nft rule drops (part of) it, so it gets abandoned
+ *   marker: short ordered message on stream 0
+ *
+ * Usage: sctp_ifwdtsn <client netns> <test>
+ * Exit status: 0 pass, 1 fail, 4 skip.
+ */
+#include <errno.h>
+#include <fcntl.h>
+#include <poll.h>
+#include <sched.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+#include <unistd.h>
+#include <arpa/inet.h>
+#include <netinet/in.h>
+#include <sys/socket.h>
+#include <linux/sctp.h>
+
+#include "kselftest.h"
+
+#ifndef SOL_SCTP
+#define SOL_SCTP	132
+#endif
+
+#define SRV_ADDR	"10.0.0.1"
+#define SRV_PORT	5000
+#define BIG_LEN		(64 * 1024)
+#define BUF_LEN		(BIG_LEN + 1024)
+#define MAXSEG		1000
+#define TIMEOUT_MS	5000
+#define MARKER		"marker"
+#define UO_MARKER	"uo-marker"
+
+struct test {
+	const char *name;
+	bool big_uo;		/* send big unordered */
+	int small_len;		/* 0: don't send the small message */
+	bool small_uo;		/* send small unordered */
+	int pd_point;		/* server SCTP_PARTIAL_DELIVERY_POINT */
+	bool expect_pd_abort;	/* PD on stream 1 must be aborted */
+	bool uo_marker;		/* then send an unordered marker on 1 */
+	bool reset;		/* SSN/TSN association reset after big */
+};
+
+static const struct test tests[] = {
+	{ .name = "ordered", .small_len = 3000 },
+	{ .name = "unordered", .big_uo = true, .small_len = 3000 },
+	{ .name = "leading_edge", .small_len = 1000, .pd_point = 2000 },
+	{ .name = "uo_pd", .small_len = 20000, .small_uo = true,
+	  .pd_point = 2000, .expect_pd_abort = true, .uo_marker = true },
+	{ .name = "reset", .reset = true },
+};
+
+static const struct test *t;
+
+static void die(const char *what)
+{
+	fprintf(stderr, "%s: %s\n", what, strerror(errno));
+	exit(KSFT_FAIL);
+}
+
+static void setopt(int fd, int opt, const void *val, socklen_t len,
+		   const char *name)
+{
+	if (setsockopt(fd, SOL_SCTP, opt, val, len) < 0) {
+		fprintf(stderr, "setsockopt(%s): %s\n", name, strerror(errno));
+		/* Interleaving disabled, or option not supported. */
+		exit(errno == EPERM || errno == ENOPROTOOPT ?
+		     KSFT_SKIP : KSFT_FAIL);
+	}
+}
+
+static void set_assoc_opt(int fd, int opt, unsigned int val, const char *name)
+{
+	struct sctp_assoc_value av = {
+		.assoc_id = SCTP_FUTURE_ASSOC,
+		.assoc_value = val,
+	};
+
+	setopt(fd, opt, &av, sizeof(av), name);
+}
+
+static void subscribe(int fd, int type)
+{
+	struct sctp_event ev = {
+		.se_assoc_id = SCTP_FUTURE_ASSOC,
+		.se_type = type,
+		.se_on = 1,
+	};
+
+	setopt(fd, SCTP_EVENT, &ev, sizeof(ev), "SCTP_EVENT");
+}
+
+static int sctp_socket(void)
+{
+	struct sctp_initmsg im = {
+		.sinit_num_ostreams = 2,
+		.sinit_max_instreams = 2,
+	};
+	struct sctp_paddrparams pp = {
+		.spp_assoc_id = SCTP_FUTURE_ASSOC,
+		.spp_flags = SPP_HB_DISABLE,
+	};
+	struct sctp_rtoinfo rto = {
+		.srto_assoc_id = SCTP_FUTURE_ASSOC,
+		.srto_initial = 300,
+		.srto_min = 300,
+		.srto_max = 1000,
+	};
+	int fd, val;
+
+	fd = socket(AF_INET, SOCK_STREAM, IPPROTO_SCTP);
+	if (fd < 0) {
+		perror("socket");
+		exit(errno == EPROTONOSUPPORT ? KSFT_SKIP : KSFT_FAIL);
+	}
+	val = 1;
+	setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &val, sizeof(val));
+
+	setopt(fd, SCTP_INITMSG, &im, sizeof(im), "SCTP_INITMSG");
+	setopt(fd, SCTP_RTOINFO, &rto, sizeof(rto), "SCTP_RTOINFO");
+	/* No HEARTBEATs: the nft rules only look at the first chunk of a
+	 * packet, and a HEARTBEAT bundled in front of DATA would bypass them.
+	 */
+	setopt(fd, SCTP_PEER_ADDR_PARAMS, &pp, sizeof(pp),
+	       "SCTP_PEER_ADDR_PARAMS");
+	set_assoc_opt(fd, SCTP_PR_SUPPORTED, 1, "SCTP_PR_SUPPORTED");
+	val = 2;
+	setopt(fd, SCTP_FRAGMENT_INTERLEAVE, &val, sizeof(val),
+	       "SCTP_FRAGMENT_INTERLEAVE");
+	set_assoc_opt(fd, SCTP_INTERLEAVING_SUPPORTED, 1,
+		      "SCTP_INTERLEAVING_SUPPORTED");
+	if (t->reset) {
+		set_assoc_opt(fd, SCTP_RECONFIG_SUPPORTED, 1,
+			      "SCTP_RECONFIG_SUPPORTED");
+		set_assoc_opt(fd, SCTP_ENABLE_STREAM_RESET,
+			      SCTP_ENABLE_RESET_ASSOC_REQ,
+			      "SCTP_ENABLE_STREAM_RESET");
+		subscribe(fd, SCTP_ASSOC_RESET_EVENT);
+	}
+	val = 1;
+	setopt(fd, SCTP_RECVRCVINFO, &val, sizeof(val), "SCTP_RECVRCVINFO");
+
+	return fd;
+}
+
+static void send_msg(int fd, int sid, bool uo, const void *buf, size_t len,
+		     bool pr)
+{
+	char cbuf[CMSG_SPACE(sizeof(struct sctp_sndinfo)) +
+		  CMSG_SPACE(sizeof(struct sctp_prinfo))] = {};
+	struct iovec iov = { .iov_base = (void *)buf, .iov_len = len };
+	struct msghdr msg = {
+		.msg_iov = &iov,
+		.msg_iovlen = 1,
+		.msg_control = cbuf,
+		.msg_controllen = CMSG_SPACE(sizeof(struct sctp_sndinfo)),
+	};
+	struct sctp_sndinfo *si;
+	struct sctp_prinfo *pi;
+	struct cmsghdr *cm;
+
+	cm = CMSG_FIRSTHDR(&msg);
+	cm->cmsg_level = IPPROTO_SCTP;
+	cm->cmsg_type = SCTP_SNDINFO;
+	cm->cmsg_len = CMSG_LEN(sizeof(*si));
+	si = (struct sctp_sndinfo *)CMSG_DATA(cm);
+	si->snd_sid = sid;
+	si->snd_flags = uo ? SCTP_UNORDERED : 0;
+
+	if (pr) {
+		/* Abandon once the chunk would need a second retransmission:
+		 * only a chunk that is lost again after being retransmitted
+		 * qualifies, so abandonment does not depend on timing.
+		 */
+		msg.msg_controllen += CMSG_SPACE(sizeof(*pi));
+		cm = CMSG_NXTHDR(&msg, cm);
+		cm->cmsg_level = IPPROTO_SCTP;
+		cm->cmsg_type = SCTP_PRINFO;
+		cm->cmsg_len = CMSG_LEN(sizeof(*pi));
+		pi = (struct sctp_prinfo *)CMSG_DATA(cm);
+		pi->pr_policy = SCTP_PR_SCTP_RTX;
+		pi->pr_value = 1;
+	}
+
+	if (sendmsg(fd, &msg, 0) != (ssize_t)len)
+		die("sendmsg");
+}
+
+static unsigned char pattern(size_t i)
+{
+	return (i * 7 + (i >> 8)) & 0xff;
+}
+
+static long long now_ms(void)
+{
+	struct timespec ts;
+
+	clock_gettime(CLOCK_MONOTONIC, &ts);
+	return ts.tv_sec * 1000LL + ts.tv_nsec / 1000000;
+}
+
+/* Wait until the client has abandoned a sent message. */
+static bool wait_abandoned(int fd)
+{
+	long long end = now_ms() + TIMEOUT_MS;
+	struct sctp_prstatus ps;
+	socklen_t len;
+
+	while (now_ms() < end) {
+		memset(&ps, 0, sizeof(ps));
+		ps.sprstat_policy = SCTP_PR_SCTP_RTX;
+		len = sizeof(ps);
+		if (getsockopt(fd, SOL_SCTP, SCTP_PR_ASSOC_STATUS, &ps,
+			       &len) < 0)
+			die("SCTP_PR_ASSOC_STATUS");
+		if (ps.sprstat_abandoned_sent)
+			return true;
+		usleep(10000);
+	}
+	return false;
+}
+
+/* Wait for a notification of @type on @fd, discarding anything else. */
+static bool wait_event(int fd, int type)
+{
+	long long end = now_ms() + TIMEOUT_MS;
+	char buf[256];
+
+	while (now_ms() < end) {
+		struct pollfd pfd = { .fd = fd, .events = POLLIN };
+		struct iovec iov = { buf, sizeof(buf) };
+		struct msghdr msg = { .msg_iov = &iov, .msg_iovlen = 1 };
+		union sctp_notification *sn = (void *)buf;
+
+		if (poll(&pfd, 1, end - now_ms()) <= 0)
+			break;
+		if (recvmsg(fd, &msg, 0) <= 0)
+			break;
+		if ((msg.msg_flags & MSG_NOTIFICATION) &&
+		    sn->sn_header.sn_type == type)
+			return true;
+	}
+	return false;
+}
+
+/* Bytes held by the server association (/proc/net/sctp/assocs RX_QUEUE). */
+static long assoc_rx_queue(void)
+{
+	/* 7 columns, TX_QUEUE, RX_QUEUE, UID, INODE, LPORT */
+	const char *fmt = "%*s %*s %*s %*s %*s %*s %*s %*u %lu %*s %*s %d";
+	unsigned long rxq;
+	char line[512];
+	long ret = -1;
+	FILE *f;
+	int lport;
+
+	f = fopen("/proc/net/sctp/assocs", "r");
+	if (!f)
+		return -1;
+	while (fgets(line, sizeof(line), f)) {
+		if (sscanf(line, fmt, &rxq, &lport) == 2 && lport == SRV_PORT)
+			ret = rxq;
+	}
+	fclose(f);
+	return ret;
+}
+
+struct server_state {
+	unsigned char *buf[2];	/* message being received, per stream */
+	size_t len[2];
+	bool big, marker, uo_marker, reset_event;
+	int pd_aborts[2];
+	int errors;
+};
+
+static void check_msg(struct server_state *s, int sid)
+{
+	unsigned char *m = s->buf[sid];
+	size_t len = s->len[sid];
+	size_t i;
+
+	s->len[sid] = 0;
+	if (sid == 0 && len == sizeof(MARKER) && !memcmp(m, MARKER, len)) {
+		s->marker = true;
+		return;
+	}
+	if (sid == 1 && len == sizeof(UO_MARKER) &&
+	    !memcmp(m, UO_MARKER, len)) {
+		s->uo_marker = true;
+		return;
+	}
+	if (sid == 0 && len == BIG_LEN) {
+		for (i = 0; i < BIG_LEN && m[i] == pattern(i); i++)
+			;
+		if (i == BIG_LEN) {
+			s->big = true;
+			return;
+		}
+		printf("big message corrupted at offset %zu\n", i);
+	} else if (sid == 1 && len > sizeof(UO_MARKER) &&
+		   !memcmp(m + len - sizeof(UO_MARKER), UO_MARKER,
+			   sizeof(UO_MARKER))) {
+		printf("unordered marker appended to the abandoned message\n");
+	} else if (sid == 1 && t->small_len) {
+		printf("abandoned message delivered (%zu bytes)\n", len);
+	} else {
+		printf("unexpected %zu byte message on stream %d\n", len, sid);
+	}
+	s->errors++;
+}
+
+/* Receive until @done(s) is true or the timeout expires. */
+static bool server_recv(int fd, struct server_state *s,
+			bool (*done)(const struct server_state *s))
+{
+	long long end = now_ms() + TIMEOUT_MS;
+	static char cbuf[CMSG_SPACE(sizeof(struct sctp_rcvinfo))];
+	static unsigned char buf[BUF_LEN];
+
+	while (!done(s)) {
+		struct pollfd pfd = { .fd = fd, .events = POLLIN };
+		struct iovec iov = { buf, sizeof(buf) };
+		struct msghdr msg = {
+			.msg_iov = &iov,
+			.msg_iovlen = 1,
+			.msg_control = cbuf,
+			.msg_controllen = sizeof(cbuf),
+		};
+		union sctp_notification *sn = (void *)buf;
+		struct sctp_rcvinfo *ri = NULL;
+		struct cmsghdr *cm;
+		long long left;
+		ssize_t n;
+		int sid;
+
+		left = end - now_ms();
+		if (left <= 0 || poll(&pfd, 1, left) <= 0) {
+			printf("timeout waiting for data\n");
+			return false;
+		}
+		n = recvmsg(fd, &msg, 0);
+		if (n <= 0) {
+			printf("recvmsg: %s\n", n ? strerror(errno) : "EOF");
+			return false;
+		}
+
+		if (msg.msg_flags & MSG_NOTIFICATION) {
+			int type = sn->sn_header.sn_type;
+
+			if (type == SCTP_PARTIAL_DELIVERY_EVENT) {
+				sid = sn->sn_pdapi_event.pdapi_stream;
+				if (sid > 1)
+					sid = 1;
+				s->pd_aborts[sid]++;
+				s->len[sid] = 0;
+			} else if (type == SCTP_ASSOC_RESET_EVENT) {
+				s->reset_event = true;
+			}
+			continue;
+		}
+
+		for (cm = CMSG_FIRSTHDR(&msg); cm; cm = CMSG_NXTHDR(&msg, cm))
+			if (cm->cmsg_level == IPPROTO_SCTP &&
+			    cm->cmsg_type == SCTP_RCVINFO)
+				ri = (struct sctp_rcvinfo *)CMSG_DATA(cm);
+		sid = ri ? ri->rcv_sid : 0;
+		if (sid > 1 || s->len[sid] + n > BUF_LEN) {
+			printf("unexpected data on stream %d\n", sid);
+			return false;
+		}
+		memcpy(s->buf[sid] + s->len[sid], buf, n);
+		s->len[sid] += n;
+		if (msg.msg_flags & MSG_EOR)
+			check_msg(s, sid);
+	}
+	return true;
+}
+
+static bool got_big(const struct server_state *s)
+{
+	return s->big || s->errors;
+}
+
+static bool got_all(const struct server_state *s)
+{
+	return (s->big && s->marker && (!t->uo_marker || s->uo_marker)) ||
+	       s->errors;
+}
+
+static int client_socket(const char *netns)
+{
+	int self, other, fd;
+	char path[256];
+
+	snprintf(path, sizeof(path), "/run/netns/%s", netns);
+	self = open("/proc/self/ns/net", O_RDONLY);
+	other = open(path, O_RDONLY);
+	if (self < 0 || other < 0)
+		die("open netns");
+	if (setns(other, CLONE_NEWNET))
+		die("setns");
+	fd = sctp_socket();
+	if (setns(self, CLONE_NEWNET))
+		die("setns");
+	close(other);
+	close(self);
+	return fd;
+}
+
+int main(int argc, char **argv)
+{
+	struct sockaddr_in sa = {
+		.sin_family = AF_INET,
+		.sin_port = htons(SRV_PORT),
+	};
+	struct server_state s = {};
+	unsigned char *big, *small;
+	int lfd, sfd, cfd, i;
+	sctp_assoc_t id = 0;
+	bool ok;
+	long rxq;
+
+	if (argc != 3) {
+		fprintf(stderr, "usage: %s <client netns> <test>\n", argv[0]);
+		return KSFT_FAIL;
+	}
+	for (i = 0; i < (int)ARRAY_SIZE(tests); i++)
+		if (!strcmp(argv[2], tests[i].name))
+			t = &tests[i];
+	if (!t) {
+		fprintf(stderr, "unknown test %s\n", argv[2]);
+		return KSFT_FAIL;
+	}
+	inet_pton(AF_INET, SRV_ADDR, &sa.sin_addr);
+
+	lfd = sctp_socket();
+	if (t->pd_point) {
+		setopt(lfd, SCTP_PARTIAL_DELIVERY_POINT, &t->pd_point,
+		       sizeof(t->pd_point), "SCTP_PARTIAL_DELIVERY_POINT");
+		subscribe(lfd, SCTP_PARTIAL_DELIVERY_EVENT);
+	}
+	if (bind(lfd, (struct sockaddr *)&sa, sizeof(sa)) || listen(lfd, 1))
+		die("bind/listen");
+
+	cfd = client_socket(argv[1]);
+	set_assoc_opt(cfd, SCTP_MAXSEG, MAXSEG, "SCTP_MAXSEG");
+	/* Round robin, so that the small message is sent between fragments
+	 * of the big one.
+	 */
+	set_assoc_opt(cfd, SCTP_STREAM_SCHEDULER, SCTP_SS_RR,
+		      "SCTP_STREAM_SCHEDULER");
+	if (connect(cfd, (struct sockaddr *)&sa, sizeof(sa)))
+		die("connect");
+	sfd = accept(lfd, NULL, NULL);
+	if (sfd < 0)
+		die("accept");
+
+	big = malloc(BIG_LEN);
+	small = malloc(t->small_len + 1);
+	s.buf[0] = malloc(BUF_LEN);
+	s.buf[1] = malloc(BUF_LEN);
+	if (!big || !small || !s.buf[0] || !s.buf[1])
+		die("malloc");
+	for (i = 0; i < BIG_LEN; i++)
+		big[i] = pattern(i);
+	memset(small, 's', t->small_len);
+
+	send_msg(cfd, 0, t->big_uo, big, BIG_LEN, false);
+	if (t->small_len)
+		send_msg(cfd, 1, t->small_uo, small, t->small_len, true);
+
+	if (t->reset) {
+		ok = server_recv(sfd, &s, got_big);
+		if (ok && setsockopt(sfd, SOL_SCTP, SCTP_RESET_ASSOC, &id,
+				     sizeof(id)))
+			die("SCTP_RESET_ASSOC");
+		/* Only send the marker once the reset is done. */
+		if (ok && !wait_event(cfd, SCTP_ASSOC_RESET_EVENT)) {
+			printf("client: no association reset event\n");
+			return KSFT_FAIL;
+		}
+	}
+	send_msg(cfd, 0, false, MARKER, sizeof(MARKER), false);
+
+	if (t->small_len && !wait_abandoned(cfd)) {
+		printf("client: small message was not abandoned\n");
+		return KSFT_FAIL;
+	}
+	if (t->uo_marker)
+		send_msg(cfd, 1, true, UO_MARKER, sizeof(UO_MARKER), false);
+
+	ok = server_recv(sfd, &s, got_all);
+	rxq = assoc_rx_queue();
+
+	if (!s.big)
+		printf("big message not delivered intact\n");
+	if (!s.marker)
+		printf("marker not delivered\n");
+	if (t->uo_marker && !s.uo_marker)
+		printf("unordered marker not delivered as its own message\n");
+	if (s.pd_aborts[0] || (s.pd_aborts[1] && !t->expect_pd_abort)) {
+		printf("unexpected partial delivery abort\n");
+		ok = false;
+	}
+	if (t->expect_pd_abort && !s.pd_aborts[1]) {
+		printf("partial delivery on stream 1 not aborted\n");
+		ok = false;
+	}
+	if (t->reset && !s.reset_event) {
+		printf("server: no association reset event\n");
+		ok = false;
+	}
+	if (rxq < 0) {
+		printf("association is gone\n");
+		ok = false;
+	} else if (rxq > 0) {
+		printf("%ld bytes left queued on the association\n", rxq);
+		ok = false;
+	}
+
+	return ok && !s.errors ? KSFT_PASS : KSFT_FAIL;
+}
diff --git a/tools/testing/selftests/net/sctp_ifwdtsn.sh b/tools/testing/selftests/net/sctp_ifwdtsn.sh
new file mode 100755
index 000000000000..2bf8d28cee52
--- /dev/null
+++ b/tools/testing/selftests/net/sctp_ifwdtsn.sh
@@ -0,0 +1,141 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+#
+# SCTP I-FORWARD-TSN handling with user message interleaving (RFC 8260).
+#
+# TOPO: CLI_NS (veth, 10.0.0.2) <---> (veth, 10.0.0.1) SRV_NS
+#
+# A large reliable message on stream 0 is sent interleaved with a PR-SCTP
+# message on stream 1 that an nft rule in SRV_NS drops, so the sender
+# abandons it and sends an I-FORWARD-TSN. The netem delay keeps the sender
+# window-limited, so the two messages' fragments interleave. Most of the
+# checks are done by sctp_ifwdtsn, see there.
+
+source lib.sh
+
+ALL_TESTS="
+	test_ordered
+	test_unordered
+	test_leading_edge
+	test_uo_pd
+	test_reset
+"
+
+# nft matches on the first chunk of a packet: chunk type at byte 12 of the
+# SCTP header, flags at byte 13, I-DATA stream id at byte 20 and FSN at
+# byte 28. SCTP_MAXSEG limits fragments to 1000 bytes and GSO is limited
+# to the MTU, so no two full-size fragments share a packet.
+NFT_SCTP="meta l4proto sctp"
+NFT_CHUNK_IDATA="@th,96,8 64"
+NFT_CHUNK_IFWDTSN="@th,96,8 194"
+NFT_FLAG_B="@th,104,8 & 0x02 == 0x02"
+NFT_SID1="@th,160,16 1"
+NFT_FSN5="@th,224,32 5"
+
+setup()
+{
+	setup_ns CLI_NS SRV_NS || return
+	defer cleanup_all_ns
+
+	ip -n "$SRV_NS" link add veth0 type veth peer name veth0 \
+		netns "$CLI_NS" || return
+	ip -n "$SRV_NS" addr add 10.0.0.1/24 dev veth0 || return
+	ip -n "$CLI_NS" addr add 10.0.0.2/24 dev veth0 || return
+	for ns in "$SRV_NS" "$CLI_NS"; do
+		ip -n "$ns" link set veth0 gso_max_size 1500 up || return
+		tc -n "$ns" qdisc add dev veth0 root netem delay 50ms || return
+		ip netns exec "$ns" sysctl -wq net.sctp.intl_enable=1 \
+			net.sctp.prsctp_enable=1 net.sctp.reconf_enable=1 ||
+			return
+	done
+}
+
+# $1: nft rules for the server's input hook (may be empty)
+nft_rules()
+{
+	ip netns exec "$SRV_NS" nft -f - <<-EOF
+		table ip sctp_test {
+			set blk {
+				type ipv4_addr
+				flags dynamic
+			}
+			chain input {
+				type filter hook input priority 0;
+				$1
+			}
+		}
+	EOF
+}
+
+# $1: test name for sctp_ifwdtsn, $2: description, $3: nft rules (optional)
+run_helper()
+{
+	if ! setup || { [ -n "$3" ] && ! nft_rules "$3"; }; then
+		log_test_skip "$2"
+		return
+	fi
+	ip netns exec "$SRV_NS" ./sctp_ifwdtsn "$CLI_NS" "$1"
+	RET=$?
+	[ "$RET" -eq "$ksft_skip" ] || [ "$RET" -eq 0 ] || RET=$ksft_fail
+	log_test "$2"
+}
+
+# Fragments of the abandoned message must not take fragments of a live
+# message below the New Cumulative TSN with them, and the abandoned
+# message's own received fragments must be freed.
+test_ordered()
+{
+	run_helper ordered \
+		"abandoned message does not purge ordered message" \
+		"$NFT_SCTP $NFT_CHUNK_IDATA $NFT_SID1 $NFT_FLAG_B drop"
+}
+
+test_unordered()
+{
+	run_helper unordered \
+		"abandoned message does not purge unordered message" \
+		"$NFT_SCTP $NFT_CHUNK_IDATA $NFT_SID1 $NFT_FLAG_B drop"
+}
+
+# Drop the abandoned message and every packet after it until one starting
+# with the I-FORWARD-TSN arrives, so that its New Cumulative TSN is the
+# highest TSN received. This must not abort the partial delivery of the
+# message on stream 0.
+test_leading_edge()
+{
+	run_helper leading_edge \
+		"I-FORWARD-TSN at the highest TSN is not a reset" "
+		$NFT_SCTP $NFT_CHUNK_IFWDTSN delete @blk { ip saddr }
+		$NFT_SCTP $NFT_CHUNK_IDATA $NFT_SID1 add @blk { ip saddr } drop
+		$NFT_SCTP ip saddr @blk drop"
+}
+
+# Abandon an unordered message during its partial delivery: the partial
+# delivery must be aborted, and the next unordered message on the stream
+# must not be appended to it.
+test_uo_pd()
+{
+	run_helper uo_pd "abandoned unordered partial delivery is aborted" \
+		"$NFT_SCTP $NFT_CHUNK_IDATA $NFT_SID1 $NFT_FSN5 drop"
+}
+
+# An SSN/TSN association reset with interleaving completes and leaves a
+# working association.
+test_reset()
+{
+	run_helper reset "association reset with interleaving"
+}
+
+require_command nft
+require_command tc
+modprobe -q sctp
+if [ ! -d /proc/net/sctp ]; then
+	echo "SKIP: SCTP not available"
+	exit "$ksft_skip"
+fi
+
+trap defer_scopes_cleanup EXIT
+
+tests_run
+
+exit "$EXIT_STATUS"
-- 
2.34.1