1 files changed, 866 insertions, 0 deletions

diff --git a/tools/testing/selftests/net/mptcp/mptcp_sockopt.c b/tools/testing/selftests/net/mptcp/mptcp_sockopt.c
new file mode 100644
index 000000000000..926b0be87c99
--- /dev/null
+++ b/tools/testing/selftests/net/mptcp/mptcp_sockopt.c
@@ -0,0 +1,866 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#define _GNU_SOURCE
+
+#include <assert.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <string.h>
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <inttypes.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <strings.h>
+#include <time.h>
+#include <unistd.h>
+
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+
+#include <netdb.h>
+#include <netinet/in.h>
+
+#include <linux/tcp.h>
+
+static int pf = AF_INET;
+
+#ifndef IPPROTO_MPTCP
+#define IPPROTO_MPTCP 262
+#endif
+#ifndef SOL_MPTCP
+#define SOL_MPTCP 284
+#endif
+
+#ifndef MPTCP_INFO
+struct mptcp_info {
+	__u8	mptcpi_subflows;
+	__u8	mptcpi_add_addr_signal;
+	__u8	mptcpi_add_addr_accepted;
+	__u8	mptcpi_subflows_max;
+	__u8	mptcpi_add_addr_signal_max;
+	__u8	mptcpi_add_addr_accepted_max;
+	__u32	mptcpi_flags;
+	__u32	mptcpi_token;
+	__u64	mptcpi_write_seq;
+	__u64	mptcpi_snd_una;
+	__u64	mptcpi_rcv_nxt;
+	__u8	mptcpi_local_addr_used;
+	__u8	mptcpi_local_addr_max;
+	__u8	mptcpi_csum_enabled;
+	__u32	mptcpi_retransmits;
+	__u64	mptcpi_bytes_retrans;
+	__u64	mptcpi_bytes_sent;
+	__u64	mptcpi_bytes_received;
+	__u64	mptcpi_bytes_acked;
+};
+
+struct mptcp_subflow_data {
+	__u32		size_subflow_data;		/* size of this structure in userspace */
+	__u32		num_subflows;			/* must be 0, set by kernel */
+	__u32		size_kernel;			/* must be 0, set by kernel */
+	__u32		size_user;			/* size of one element in data[] */
+} __attribute__((aligned(8)));
+
+struct mptcp_subflow_addrs {
+	union {
+		__kernel_sa_family_t sa_family;
+		struct sockaddr sa_local;
+		struct sockaddr_in sin_local;
+		struct sockaddr_in6 sin6_local;
+		struct __kernel_sockaddr_storage ss_local;
+	};
+	union {
+		struct sockaddr sa_remote;
+		struct sockaddr_in sin_remote;
+		struct sockaddr_in6 sin6_remote;
+		struct __kernel_sockaddr_storage ss_remote;
+	};
+};
+
+#define MPTCP_INFO		1
+#define MPTCP_TCPINFO		2
+#define MPTCP_SUBFLOW_ADDRS	3
+#endif
+
+#ifndef MPTCP_FULL_INFO
+struct mptcp_subflow_info {
+	__u32				id;
+	struct mptcp_subflow_addrs	addrs;
+};
+
+struct mptcp_full_info {
+	__u32		size_tcpinfo_kernel;	/* must be 0, set by kernel */
+	__u32		size_tcpinfo_user;
+	__u32		size_sfinfo_kernel;	/* must be 0, set by kernel */
+	__u32		size_sfinfo_user;
+	__u32		num_subflows;		/* must be 0, set by kernel (real subflow count) */
+	__u32		size_arrays_user;	/* max subflows that userspace is interested in;
+						 * the buffers at subflow_info/tcp_info
+						 * are respectively at least:
+						 *  size_arrays * size_sfinfo_user
+						 *  size_arrays * size_tcpinfo_user
+						 * bytes wide
+						 */
+	__aligned_u64		subflow_info;
+	__aligned_u64		tcp_info;
+	struct mptcp_info	mptcp_info;
+};
+
+#define MPTCP_FULL_INFO		4
+#endif
+
+struct so_state {
+	struct mptcp_info mi;
+	struct mptcp_info last_sample;
+	struct tcp_info tcp_info;
+	struct mptcp_subflow_addrs addrs;
+	uint64_t mptcpi_rcv_delta;
+	uint64_t tcpi_rcv_delta;
+	bool pkt_stats_avail;
+};
+
+#ifndef MIN
+#define MIN(a, b) ((a) < (b) ? (a) : (b))
+#endif
+
+static void die_perror(const char *msg)
+{
+	perror(msg);
+	exit(1);
+}
+
+static void die_usage(int r)
+{
+	fprintf(stderr, "Usage: mptcp_sockopt [-6]\n");
+	exit(r);
+}
+
+static void xerror(const char *fmt, ...)
+{
+	va_list ap;
+
+	va_start(ap, fmt);
+	vfprintf(stderr, fmt, ap);
+	va_end(ap);
+	fputc('\n', stderr);
+	exit(1);
+}
+
+static const char *getxinfo_strerr(int err)
+{
+	if (err == EAI_SYSTEM)
+		return strerror(errno);
+
+	return gai_strerror(err);
+}
+
+static void xgetaddrinfo(const char *node, const char *service,
+			 const struct addrinfo *hints,
+			 struct addrinfo **res)
+{
+	int err = getaddrinfo(node, service, hints, res);
+
+	if (err) {
+		const char *errstr = getxinfo_strerr(err);
+
+		fprintf(stderr, "Fatal: getaddrinfo(%s:%s): %s\n",
+			node ? node : "", service ? service : "", errstr);
+		exit(1);
+	}
+}
+
+static int sock_listen_mptcp(const char * const listenaddr,
+			     const char * const port)
+{
+	int sock = -1;
+	struct addrinfo hints = {
+		.ai_protocol = IPPROTO_TCP,
+		.ai_socktype = SOCK_STREAM,
+		.ai_flags = AI_PASSIVE | AI_NUMERICHOST
+	};
+
+	hints.ai_family = pf;
+
+	struct addrinfo *a, *addr;
+	int one = 1;
+
+	xgetaddrinfo(listenaddr, port, &hints, &addr);
+	hints.ai_family = pf;
+
+	for (a = addr; a; a = a->ai_next) {
+		sock = socket(a->ai_family, a->ai_socktype, IPPROTO_MPTCP);
+		if (sock < 0)
+			continue;
+
+		if (-1 == setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &one,
+				     sizeof(one)))
+			perror("setsockopt");
+
+		if (bind(sock, a->ai_addr, a->ai_addrlen) == 0)
+			break; /* success */
+
+		perror("bind");
+		close(sock);
+		sock = -1;
+	}
+
+	freeaddrinfo(addr);
+
+	if (sock < 0)
+		xerror("could not create listen socket");
+
+	if (listen(sock, 20))
+		die_perror("listen");
+
+	return sock;
+}
+
+static int sock_connect_mptcp(const char * const remoteaddr,
+			      const char * const port, int proto)
+{
+	struct addrinfo hints = {
+		.ai_protocol = IPPROTO_TCP,
+		.ai_socktype = SOCK_STREAM,
+	};
+	struct addrinfo *a, *addr;
+	int sock = -1;
+
+	hints.ai_family = pf;
+
+	xgetaddrinfo(remoteaddr, port, &hints, &addr);
+	for (a = addr; a; a = a->ai_next) {
+		sock = socket(a->ai_family, a->ai_socktype, proto);
+		if (sock < 0)
+			continue;
+
+		if (connect(sock, a->ai_addr, a->ai_addrlen) == 0)
+			break; /* success */
+
+		die_perror("connect");
+	}
+
+	if (sock < 0)
+		xerror("could not create connect socket");
+
+	freeaddrinfo(addr);
+	return sock;
+}
+
+static void parse_opts(int argc, char **argv)
+{
+	int c;
+
+	while ((c = getopt(argc, argv, "h6")) != -1) {
+		switch (c) {
+		case 'h':
+			die_usage(0);
+			break;
+		case '6':
+			pf = AF_INET6;
+			break;
+		default:
+			die_usage(1);
+			break;
+		}
+	}
+}
+
+static void do_getsockopt_bogus_sf_data(int fd, int optname)
+{
+	struct mptcp_subflow_data good_data;
+	struct bogus_data {
+		struct mptcp_subflow_data d;
+		char buf[2];
+	} bd;
+	socklen_t olen, _olen;
+	int ret;
+
+	memset(&bd, 0, sizeof(bd));
+	memset(&good_data, 0, sizeof(good_data));
+
+	olen = sizeof(good_data);
+	good_data.size_subflow_data = olen;
+
+	ret = getsockopt(fd, SOL_MPTCP, optname, &bd, &olen);
+	assert(ret < 0); /* 0 size_subflow_data */
+	assert(olen == sizeof(good_data));
+
+	bd.d = good_data;
+
+	ret = getsockopt(fd, SOL_MPTCP, optname, &bd, &olen);
+	assert(ret == 0);
+	assert(olen == sizeof(good_data));
+	assert(bd.d.num_subflows == 1);
+	assert(bd.d.size_kernel > 0);
+	assert(bd.d.size_user == 0);
+
+	bd.d = good_data;
+	_olen = rand() % olen;
+	olen = _olen;
+	ret = getsockopt(fd, SOL_MPTCP, optname, &bd, &olen);
+	assert(ret < 0);	/* bogus olen */
+	assert(olen == _olen);	/* must be unchanged */
+
+	bd.d = good_data;
+	olen = sizeof(good_data);
+	bd.d.size_kernel = 1;
+	ret = getsockopt(fd, SOL_MPTCP, optname, &bd, &olen);
+	assert(ret < 0); /* size_kernel not 0 */
+
+	bd.d = good_data;
+	olen = sizeof(good_data);
+	bd.d.num_subflows = 1;
+	ret = getsockopt(fd, SOL_MPTCP, optname, &bd, &olen);
+	assert(ret < 0); /* num_subflows not 0 */
+
+	/* forward compat check: larger struct mptcp_subflow_data on 'old' kernel */
+	bd.d = good_data;
+	olen = sizeof(bd);
+	bd.d.size_subflow_data = sizeof(bd);
+
+	ret = getsockopt(fd, SOL_MPTCP, optname, &bd, &olen);
+	assert(ret == 0);
+
+	/* olen must be truncated to real data size filled by kernel: */
+	assert(olen == sizeof(good_data));
+
+	assert(bd.d.size_subflow_data == sizeof(bd));
+
+	bd.d = good_data;
+	bd.d.size_subflow_data += 1;
+	bd.d.size_user = 1;
+	olen = bd.d.size_subflow_data + 1;
+	_olen = olen;
+
+	ret = getsockopt(fd, SOL_MPTCP, optname, &bd, &_olen);
+	assert(ret == 0);
+
+	/* no truncation, kernel should have filled 1 byte of optname payload in buf[1]: */
+	assert(olen == _olen);
+
+	assert(bd.d.size_subflow_data == sizeof(good_data) + 1);
+	assert(bd.buf[0] == 0);
+}
+
+static void do_getsockopt_mptcp_info(struct so_state *s, int fd, size_t w)
+{
+	struct mptcp_info i;
+	socklen_t olen;
+	int ret;
+
+	olen = sizeof(i);
+	ret = getsockopt(fd, SOL_MPTCP, MPTCP_INFO, &i, &olen);
+
+	if (ret < 0)
+		die_perror("getsockopt MPTCP_INFO");
+
+	s->pkt_stats_avail = olen >= sizeof(i);
+
+	s->last_sample = i;
+	if (s->mi.mptcpi_write_seq == 0)
+		s->mi = i;
+
+	assert(s->mi.mptcpi_write_seq + w == i.mptcpi_write_seq);
+
+	s->mptcpi_rcv_delta = i.mptcpi_rcv_nxt - s->mi.mptcpi_rcv_nxt;
+}
+
+static void do_getsockopt_tcp_info(struct so_state *s, int fd, size_t r, size_t w)
+{
+	struct my_tcp_info {
+		struct mptcp_subflow_data d;
+		struct tcp_info ti[2];
+	} ti;
+	int ret, tries = 5;
+	socklen_t olen;
+
+	do {
+		memset(&ti, 0, sizeof(ti));
+
+		ti.d.size_subflow_data = sizeof(struct mptcp_subflow_data);
+		ti.d.size_user = sizeof(struct tcp_info);
+		olen = sizeof(ti);
+
+		ret = getsockopt(fd, SOL_MPTCP, MPTCP_TCPINFO, &ti, &olen);
+		if (ret < 0)
+			xerror("getsockopt MPTCP_TCPINFO (tries %d, %m)");
+
+		assert(olen <= sizeof(ti));
+		assert(ti.d.size_kernel > 0);
+		assert(ti.d.size_user ==
+		       MIN(ti.d.size_kernel, sizeof(struct tcp_info)));
+		assert(ti.d.num_subflows == 1);
+
+		assert(olen > (socklen_t)sizeof(struct mptcp_subflow_data));
+		olen -= sizeof(struct mptcp_subflow_data);
+		assert(olen == ti.d.size_user);
+
+		s->tcp_info = ti.ti[0];
+
+		if (ti.ti[0].tcpi_bytes_sent == w &&
+		    ti.ti[0].tcpi_bytes_received == r)
+			goto done;
+
+		if (r == 0 && ti.ti[0].tcpi_bytes_sent == w &&
+		    ti.ti[0].tcpi_bytes_received) {
+			s->tcpi_rcv_delta = ti.ti[0].tcpi_bytes_received;
+			goto done;
+		}
+
+		/* wait and repeat, might be that tx is still ongoing */
+		sleep(1);
+	} while (tries-- > 0);
+
+	xerror("tcpi_bytes_sent %" PRIu64 ", want %zu. tcpi_bytes_received %" PRIu64 ", want %zu",
+		ti.ti[0].tcpi_bytes_sent, w, ti.ti[0].tcpi_bytes_received, r);
+
+done:
+	do_getsockopt_bogus_sf_data(fd, MPTCP_TCPINFO);
+}
+
+static void do_getsockopt_subflow_addrs(struct so_state *s, int fd)
+{
+	struct sockaddr_storage remote, local;
+	socklen_t olen, rlen, llen;
+	int ret;
+	struct my_addrs {
+		struct mptcp_subflow_data d;
+		struct mptcp_subflow_addrs addr[2];
+	} addrs;
+
+	memset(&addrs, 0, sizeof(addrs));
+	memset(&local, 0, sizeof(local));
+	memset(&remote, 0, sizeof(remote));
+
+	addrs.d.size_subflow_data = sizeof(struct mptcp_subflow_data);
+	addrs.d.size_user = sizeof(struct mptcp_subflow_addrs);
+	olen = sizeof(addrs);
+
+	ret = getsockopt(fd, SOL_MPTCP, MPTCP_SUBFLOW_ADDRS, &addrs, &olen);
+	if (ret < 0)
+		die_perror("getsockopt MPTCP_SUBFLOW_ADDRS");
+
+	assert(olen <= sizeof(addrs));
+	assert(addrs.d.size_kernel > 0);
+	assert(addrs.d.size_user ==
+	       MIN(addrs.d.size_kernel, sizeof(struct mptcp_subflow_addrs)));
+	assert(addrs.d.num_subflows == 1);
+
+	assert(olen > (socklen_t)sizeof(struct mptcp_subflow_data));
+	olen -= sizeof(struct mptcp_subflow_data);
+	assert(olen == addrs.d.size_user);
+
+	llen = sizeof(local);
+	ret = getsockname(fd, (struct sockaddr *)&local, &llen);
+	if (ret < 0)
+		die_perror("getsockname");
+	rlen = sizeof(remote);
+	ret = getpeername(fd, (struct sockaddr *)&remote, &rlen);
+	if (ret < 0)
+		die_perror("getpeername");
+
+	assert(rlen > 0);
+	assert(rlen == llen);
+
+	assert(remote.ss_family == local.ss_family);
+
+	assert(memcmp(&local, &addrs.addr[0].ss_local, sizeof(local)) == 0);
+	assert(memcmp(&remote, &addrs.addr[0].ss_remote, sizeof(remote)) == 0);
+	s->addrs = addrs.addr[0];
+
+	memset(&addrs, 0, sizeof(addrs));
+
+	addrs.d.size_subflow_data = sizeof(struct mptcp_subflow_data);
+	addrs.d.size_user = sizeof(sa_family_t);
+	olen = sizeof(addrs.d) + sizeof(sa_family_t);
+
+	ret = getsockopt(fd, SOL_MPTCP, MPTCP_SUBFLOW_ADDRS, &addrs, &olen);
+	assert(ret == 0);
+	assert(olen == sizeof(addrs.d) + sizeof(sa_family_t));
+
+	assert(addrs.addr[0].sa_family == pf);
+	assert(addrs.addr[0].sa_family == local.ss_family);
+
+	assert(memcmp(&local, &addrs.addr[0].ss_local, sizeof(local)) != 0);
+	assert(memcmp(&remote, &addrs.addr[0].ss_remote, sizeof(remote)) != 0);
+
+	do_getsockopt_bogus_sf_data(fd, MPTCP_SUBFLOW_ADDRS);
+}
+
+static void do_getsockopt_mptcp_full_info(struct so_state *s, int fd)
+{
+	size_t data_size = sizeof(struct mptcp_full_info);
+	struct mptcp_subflow_info sfinfo[2];
+	struct tcp_info tcp_info[2];
+	struct mptcp_full_info mfi;
+	socklen_t olen;
+	int ret;
+
+	memset(&mfi, 0, data_size);
+	memset(tcp_info, 0, sizeof(tcp_info));
+	memset(sfinfo, 0, sizeof(sfinfo));
+
+	mfi.size_tcpinfo_user = sizeof(struct tcp_info);
+	mfi.size_sfinfo_user = sizeof(struct mptcp_subflow_info);
+	mfi.size_arrays_user = 2;
+	mfi.subflow_info = (unsigned long)&sfinfo[0];
+	mfi.tcp_info = (unsigned long)&tcp_info[0];
+	olen = data_size;
+
+	ret = getsockopt(fd, SOL_MPTCP, MPTCP_FULL_INFO, &mfi, &olen);
+	if (ret < 0) {
+		if (errno == EOPNOTSUPP) {
+			perror("MPTCP_FULL_INFO test skipped");
+			return;
+		}
+		xerror("getsockopt MPTCP_FULL_INFO");
+	}
+
+	assert(olen <= data_size);
+	assert(mfi.size_tcpinfo_kernel > 0);
+	assert(mfi.size_tcpinfo_user ==
+	       MIN(mfi.size_tcpinfo_kernel, sizeof(struct tcp_info)));
+	assert(mfi.size_sfinfo_kernel > 0);
+	assert(mfi.size_sfinfo_user ==
+	       MIN(mfi.size_sfinfo_kernel, sizeof(struct mptcp_subflow_info)));
+	assert(mfi.num_subflows == 1);
+
+	/* Tolerate future extension to mptcp_info struct and running newer
+	 * test on top of older kernel.
+	 * Anyway any kernel supporting MPTCP_FULL_INFO must at least include
+	 * the following in mptcp_info.
+	 */
+	assert(olen > (socklen_t)__builtin_offsetof(struct mptcp_full_info, tcp_info));
+	assert(mfi.mptcp_info.mptcpi_subflows == 0);
+	assert(mfi.mptcp_info.mptcpi_bytes_sent == s->last_sample.mptcpi_bytes_sent);
+	assert(mfi.mptcp_info.mptcpi_bytes_received == s->last_sample.mptcpi_bytes_received);
+
+	assert(sfinfo[0].id == 1);
+	assert(tcp_info[0].tcpi_bytes_sent == s->tcp_info.tcpi_bytes_sent);
+	assert(tcp_info[0].tcpi_bytes_received == s->tcp_info.tcpi_bytes_received);
+	assert(!memcmp(&sfinfo->addrs, &s->addrs, sizeof(struct mptcp_subflow_addrs)));
+}
+
+static void do_getsockopts(struct so_state *s, int fd, size_t r, size_t w)
+{
+	do_getsockopt_mptcp_info(s, fd, w);
+
+	do_getsockopt_tcp_info(s, fd, r, w);
+
+	do_getsockopt_subflow_addrs(s, fd);
+
+	if (r)
+		do_getsockopt_mptcp_full_info(s, fd);
+}
+
+static void connect_one_server(int fd, int pipefd)
+{
+	char buf[4096], buf2[4096];
+	size_t len, i, total;
+	struct so_state s;
+	bool eof = false;
+	ssize_t ret;
+
+	memset(&s, 0, sizeof(s));
+
+	len = rand() % (sizeof(buf) - 1);
+
+	if (len < 128)
+		len = 128;
+
+	for (i = 0; i < len ; i++) {
+		buf[i] = rand() % 26;
+		buf[i] += 'A';
+	}
+
+	buf[i] = '\n';
+
+	do_getsockopts(&s, fd, 0, 0);
+
+	/* un-block server */
+	ret = read(pipefd, buf2, 4);
+	assert(ret == 4);
+	close(pipefd);
+
+	assert(strncmp(buf2, "xmit", 4) == 0);
+
+	ret = write(fd, buf, len);
+	if (ret < 0)
+		die_perror("write");
+
+	if (ret != (ssize_t)len)
+		xerror("short write");
+
+	total = 0;
+	do {
+		ret = read(fd, buf2 + total, sizeof(buf2) - total);
+		if (ret < 0)
+			die_perror("read");
+		if (ret == 0) {
+			eof = true;
+			break;
+		}
+
+		total += ret;
+	} while (total < len);
+
+	if (total != len)
+		xerror("total %lu, len %lu eof %d\n", total, len, eof);
+
+	if (memcmp(buf, buf2, len))
+		xerror("data corruption");
+
+	if (s.tcpi_rcv_delta)
+		assert(s.tcpi_rcv_delta <= total);
+
+	do_getsockopts(&s, fd, ret, ret);
+
+	if (eof)
+		total += 1; /* sequence advances due to FIN */
+
+	assert(s.mptcpi_rcv_delta == (uint64_t)total);
+	close(fd);
+}
+
+static void process_one_client(int fd, int pipefd)
+{
+	ssize_t ret, ret2, ret3;
+	struct so_state s;
+	char buf[4096];
+
+	memset(&s, 0, sizeof(s));
+	do_getsockopts(&s, fd, 0, 0);
+
+	ret = write(pipefd, "xmit", 4);
+	assert(ret == 4);
+
+	ret = read(fd, buf, sizeof(buf));
+	if (ret < 0)
+		die_perror("read");
+
+	assert(s.mptcpi_rcv_delta <= (uint64_t)ret);
+
+	if (s.tcpi_rcv_delta)
+		assert(s.tcpi_rcv_delta == (uint64_t)ret);
+
+	ret2 = write(fd, buf, ret);
+	if (ret2 < 0)
+		die_perror("write");
+
+	/* wait for hangup */
+	ret3 = read(fd, buf, 1);
+	if (ret3 != 0)
+		xerror("expected EOF, got %lu", ret3);
+
+	do_getsockopts(&s, fd, ret, ret2);
+	if (s.mptcpi_rcv_delta != (uint64_t)ret + 1)
+		xerror("mptcpi_rcv_delta %" PRIu64 ", expect %" PRIu64, s.mptcpi_rcv_delta, ret + 1, s.mptcpi_rcv_delta - ret);
+
+	/* be nice when running on top of older kernel */
+	if (s.pkt_stats_avail) {
+		if (s.last_sample.mptcpi_bytes_sent != ret2)
+			xerror("mptcpi_bytes_sent %" PRIu64 ", expect %" PRIu64,
+			       s.last_sample.mptcpi_bytes_sent, ret2,
+			       s.last_sample.mptcpi_bytes_sent - ret2);
+		if (s.last_sample.mptcpi_bytes_received != ret)
+			xerror("mptcpi_bytes_received %" PRIu64 ", expect %" PRIu64,
+			       s.last_sample.mptcpi_bytes_received, ret,
+			       s.last_sample.mptcpi_bytes_received - ret);
+		if (s.last_sample.mptcpi_bytes_acked != ret)
+			xerror("mptcpi_bytes_acked %" PRIu64 ", expect %" PRIu64,
+			       s.last_sample.mptcpi_bytes_acked, ret2,
+			       s.last_sample.mptcpi_bytes_acked - ret2);
+	}
+
+	close(fd);
+}
+
+static int xaccept(int s)
+{
+	int fd = accept(s, NULL, 0);
+
+	if (fd < 0)
+		die_perror("accept");
+
+	return fd;
+}
+
+static int server(int pipefd)
+{
+	int fd = -1, r;
+
+	switch (pf) {
+	case AF_INET:
+		fd = sock_listen_mptcp("127.0.0.1", "15432");
+		break;
+	case AF_INET6:
+		fd = sock_listen_mptcp("::1", "15432");
+		break;
+	default:
+		xerror("Unknown pf %d\n", pf);
+		break;
+	}
+
+	r = write(pipefd, "conn", 4);
+	assert(r == 4);
+
+	alarm(15);
+	r = xaccept(fd);
+
+	process_one_client(r, pipefd);
+
+	return 0;
+}
+
+static void test_ip_tos_sockopt(int fd)
+{
+	uint8_t tos_in, tos_out;
+	socklen_t s;
+	int r;
+
+	tos_in = rand() & 0xfc;
+	r = setsockopt(fd, SOL_IP, IP_TOS, &tos_in, sizeof(tos_out));
+	if (r != 0)
+		die_perror("setsockopt IP_TOS");
+
+	tos_out = 0;
+	s = sizeof(tos_out);
+	r = getsockopt(fd, SOL_IP, IP_TOS, &tos_out, &s);
+	if (r != 0)
+		die_perror("getsockopt IP_TOS");
+
+	if (tos_in != tos_out)
+		xerror("tos %x != %x socklen_t %d\n", tos_in, tos_out, s);
+
+	if (s != 1)
+		xerror("tos should be 1 byte");
+
+	s = 0;
+	r = getsockopt(fd, SOL_IP, IP_TOS, &tos_out, &s);
+	if (r != 0)
+		die_perror("getsockopt IP_TOS 0");
+	if (s != 0)
+		xerror("expect socklen_t == 0");
+
+	s = -1;
+	r = getsockopt(fd, SOL_IP, IP_TOS, &tos_out, &s);
+	if (r != -1 && errno != EINVAL)
+		die_perror("getsockopt IP_TOS did not indicate -EINVAL");
+	if (s != -1)
+		xerror("expect socklen_t == -1");
+}
+
+static int client(int pipefd)
+{
+	int fd = -1;
+
+	alarm(15);
+
+	switch (pf) {
+	case AF_INET:
+		fd = sock_connect_mptcp("127.0.0.1", "15432", IPPROTO_MPTCP);
+		break;
+	case AF_INET6:
+		fd = sock_connect_mptcp("::1", "15432", IPPROTO_MPTCP);
+		break;
+	default:
+		xerror("Unknown pf %d\n", pf);
+	}
+
+	test_ip_tos_sockopt(fd);
+
+	connect_one_server(fd, pipefd);
+
+	return 0;
+}
+
+static pid_t xfork(void)
+{
+	pid_t p = fork();
+
+	if (p < 0)
+		die_perror("fork");
+
+	return p;
+}
+
+static int rcheck(int wstatus, const char *what)
+{
+	if (WIFEXITED(wstatus)) {
+		if (WEXITSTATUS(wstatus) == 0)
+			return 0;
+		fprintf(stderr, "%s exited, status=%d\n", what, WEXITSTATUS(wstatus));
+		return WEXITSTATUS(wstatus);
+	} else if (WIFSIGNALED(wstatus)) {
+		xerror("%s killed by signal %d\n", what, WTERMSIG(wstatus));
+	} else if (WIFSTOPPED(wstatus)) {
+		xerror("%s stopped by signal %d\n", what, WSTOPSIG(wstatus));
+	}
+
+	return 111;
+}
+
+static void init_rng(void)
+{
+	int fd = open("/dev/urandom", O_RDONLY);
+
+	if (fd >= 0) {
+		unsigned int foo;
+		ssize_t ret;
+
+		/* can't fail */
+		ret = read(fd, &foo, sizeof(foo));
+		assert(ret == sizeof(foo));
+
+		close(fd);
+		srand(foo);
+	} else {
+		srand(time(NULL));
+	}
+}
+
+int main(int argc, char *argv[])
+{
+	int e1, e2, wstatus;
+	pid_t s, c, ret;
+	int pipefds[2];
+
+	parse_opts(argc, argv);
+
+	init_rng();
+
+	e1 = pipe(pipefds);
+	if (e1 < 0)
+		die_perror("pipe");
+
+	s = xfork();
+	if (s == 0)
+		return server(pipefds[1]);
+
+	close(pipefds[1]);
+
+	/* wait until server bound a socket */
+	e1 = read(pipefds[0], &e1, 4);
+	assert(e1 == 4);
+
+	c = xfork();
+	if (c == 0)
+		return client(pipefds[0]);
+
+	close(pipefds[0]);
+
+	ret = waitpid(s, &wstatus, 0);
+	if (ret == -1)
+		die_perror("waitpid");
+	e1 = rcheck(wstatus, "server");
+	ret = waitpid(c, &wstatus, 0);
+	if (ret == -1)
+		die_perror("waitpid");
+	e2 = rcheck(wstatus, "client");
+
+	return e1 ? e1 : e2;
+}