selftests: udp gso with connected sockets

Connected sockets use path mtu instead of device mtu.

Test this path by inserting a route mtu that is lower than the device
mtu. Verify that the path mtu for the connection matches this lower
number, then run the same test as in the connectionless case.
Signed-off-by: NWillem de Bruijn <willemb@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

tools/testing/selftests/net/udpgso.c

@@ -47,6 +47,7 @@
 
 static bool		cfg_do_ipv4;
 static bool		cfg_do_ipv6;
+static bool		cfg_do_connected;
 static bool		cfg_do_connectionless;
 static bool		cfg_do_setsockopt;
 static int		cfg_specific_test_id = -1;
@@ -273,6 +274,101 @@ static void set_pmtu_discover(int fd, bool is_ipv4)
 		error(1, errno, "setsockopt path mtu");
 }
 
+static unsigned int get_path_mtu(int fd, bool is_ipv4)
+{
+	socklen_t vallen;
+	unsigned int mtu;
+	int ret;
+
+	vallen = sizeof(mtu);
+	if (is_ipv4)
+		ret = getsockopt(fd, SOL_IP, IP_MTU, &mtu, &vallen);
+	else
+		ret = getsockopt(fd, SOL_IPV6, IPV6_MTU, &mtu, &vallen);
+
+	if (ret)
+		error(1, errno, "getsockopt mtu");
+
+
+	fprintf(stderr, "path mtu (read):  %u\n", mtu);
+	return mtu;
+}
+
+/* very wordy version of system("ip route add dev lo mtu 1500 127.0.0.3/32") */
+static void set_route_mtu(int mtu, bool is_ipv4)
+{
+	struct sockaddr_nl nladdr = { .nl_family = AF_NETLINK };
+	struct nlmsghdr *nh;
+	struct rtattr *rta;
+	struct rtmsg *rt;
+	char data[NLMSG_ALIGN(sizeof(*nh)) +
+		  NLMSG_ALIGN(sizeof(*rt)) +
+		  NLMSG_ALIGN(RTA_LENGTH(sizeof(addr6))) +
+		  NLMSG_ALIGN(RTA_LENGTH(sizeof(int))) +
+		  NLMSG_ALIGN(RTA_LENGTH(0) + RTA_LENGTH(sizeof(int)))];
+	int fd, ret, alen, off = 0;
+
+	alen = is_ipv4 ? sizeof(addr4) : sizeof(addr6);
+
+	fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
+	if (fd == -1)
+		error(1, errno, "socket netlink");
+
+	memset(data, 0, sizeof(data));
+
+	nh = (void *)data;
+	nh->nlmsg_type = RTM_NEWROUTE;
+	nh->nlmsg_flags = NLM_F_REQUEST | NLM_F_CREATE;
+	off += NLMSG_ALIGN(sizeof(*nh));
+
+	rt = (void *)(data + off);
+	rt->rtm_family = is_ipv4 ? AF_INET : AF_INET6;
+	rt->rtm_table = RT_TABLE_MAIN;
+	rt->rtm_dst_len = alen << 3;
+	rt->rtm_protocol = RTPROT_BOOT;
+	rt->rtm_scope = RT_SCOPE_UNIVERSE;
+	rt->rtm_type = RTN_UNICAST;
+	off += NLMSG_ALIGN(sizeof(*rt));
+
+	rta = (void *)(data + off);
+	rta->rta_type = RTA_DST;
+	rta->rta_len = RTA_LENGTH(alen);
+	if (is_ipv4)
+		memcpy(RTA_DATA(rta), &addr4, alen);
+	else
+		memcpy(RTA_DATA(rta), &addr6, alen);
+	off += NLMSG_ALIGN(rta->rta_len);
+
+	rta = (void *)(data + off);
+	rta->rta_type = RTA_OIF;
+	rta->rta_len = RTA_LENGTH(sizeof(int));
+	*((int *)(RTA_DATA(rta))) = 1; //if_nametoindex("lo");
+	off += NLMSG_ALIGN(rta->rta_len);
+
+	/* MTU is a subtype in a metrics type */
+	rta = (void *)(data + off);
+	rta->rta_type = RTA_METRICS;
+	rta->rta_len = RTA_LENGTH(0) + RTA_LENGTH(sizeof(int));
+	off += NLMSG_ALIGN(rta->rta_len);
+
+	/* now fill MTU subtype. Note that it fits within above rta_len */
+	rta = (void *)(((char *) rta) + RTA_LENGTH(0));
+	rta->rta_type = RTAX_MTU;
+	rta->rta_len = RTA_LENGTH(sizeof(int));
+	*((int *)(RTA_DATA(rta))) = mtu;
+
+	nh->nlmsg_len = off;
+
+	ret = sendto(fd, data, off, 0, (void *)&nladdr, sizeof(nladdr));
+	if (ret != off)
+		error(1, errno, "send netlink: %uB != %uB\n", ret, off);
+
+	if (close(fd))
+		error(1, errno, "close netlink");
+
+	fprintf(stderr, "route mtu (test): %u\n", mtu);
+}
+
 static bool send_one(int fd, int len, int gso_len,
 		     struct sockaddr *addr, socklen_t alen)
 {
@@ -391,7 +487,7 @@ static void run_all(int fdt, int fdr, struct sockaddr *addr, socklen_t alen)
 static void run_test(struct sockaddr *addr, socklen_t alen)
 {
 	struct timeval tv = { .tv_usec = 100 * 1000 };
-	int fdr, fdt;
+	int fdr, fdt, val;
 
 	fdr = socket(addr->sa_family, SOCK_DGRAM, 0);
 	if (fdr == -1)
@@ -416,6 +512,20 @@ static void run_test(struct sockaddr *addr, socklen_t alen)
 		run_all(fdt, fdr, addr, alen);
 	}
 
+	if (cfg_do_connected) {
+		set_device_mtu(fdt, CONST_MTU_TEST + 100);
+		set_route_mtu(CONST_MTU_TEST, addr->sa_family == AF_INET);
+
+		if (connect(fdt, addr, alen))
+			error(1, errno, "connect");
+
+		val = get_path_mtu(fdt, addr->sa_family == AF_INET);
+		if (val != CONST_MTU_TEST)
+			error(1, 0, "bad path mtu %u\n", val);
+
+		run_all(fdt, fdr, addr, 0 /* use connected addr */);
+	}
+
 	if (close(fdt))
 		error(1, errno, "close t");
 	if (close(fdr))
@@ -448,7 +558,7 @@ static void parse_opts(int argc, char **argv)
 {
 	int c;
 
-	while ((c = getopt(argc, argv, "46Cst:")) != -1) {
+	while ((c = getopt(argc, argv, "46cCst:")) != -1) {
 		switch (c) {
 		case '4':
 			cfg_do_ipv4 = true;
@@ -456,6 +566,9 @@ static void parse_opts(int argc, char **argv)
 		case '6':
 			cfg_do_ipv6 = true;
 			break;
+		case 'c':
+			cfg_do_connected = true;
+			break;
 		case 'C':
 			cfg_do_connectionless = true;
 			break;

tools/testing/selftests/net/udpgso.sh

@@ -14,3 +14,10 @@ echo "ipv6 cmsg"
 
 echo "ipv6 setsockopt"
 ./in_netns.sh ./udpgso -6 -C -s
+
+echo "ipv4 connected"
+./in_netns.sh ./udpgso -4 -c
+
+# blocked on 2nd loopback address
+# echo "ipv6 connected"
+# ./in_netns.sh ./udpgso -6 -c