--- /dev/null
+// SPDX-License-Identifier: GPL-2.0
+
+#define _GNU_SOURCE
+
+#include <stddef.h>
+#include <arpa/inet.h>
+#include <error.h>
+#include <errno.h>
+#include <net/if.h>
+#include <linux/in.h>
+#include <linux/netlink.h>
+#include <linux/rtnetlink.h>
+#include <netinet/if_ether.h>
+#include <netinet/ip.h>
+#include <netinet/ip6.h>
+#include <netinet/udp.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#ifndef ETH_MAX_MTU
+#define ETH_MAX_MTU 0xFFFFU
+#endif
+
+#ifndef UDP_SEGMENT
+#define UDP_SEGMENT 103
+#endif
+
+#define CONST_MTU_TEST 1500
+
+#define CONST_HDRLEN_V4 (sizeof(struct iphdr) + sizeof(struct udphdr))
+#define CONST_HDRLEN_V6 (sizeof(struct ip6_hdr) + sizeof(struct udphdr))
+
+#define CONST_MSS_V4 (CONST_MTU_TEST - CONST_HDRLEN_V4)
+#define CONST_MSS_V6 (CONST_MTU_TEST - CONST_HDRLEN_V6)
+
+#define CONST_MAX_SEGS_V4 (ETH_MAX_MTU / CONST_MSS_V4)
+#define CONST_MAX_SEGS_V6 (ETH_MAX_MTU / CONST_MSS_V6)
+
+static bool cfg_do_ipv4;
+static bool cfg_do_ipv6;
+static bool cfg_do_connectionless;
+static bool cfg_do_setsockopt;
+static int cfg_specific_test_id = -1;
+
+static const char cfg_ifname[] = "lo";
+static unsigned short cfg_port = 9000;
+
+static char buf[ETH_MAX_MTU];
+
+struct testcase {
+ int tlen; /* send() buffer size, may exceed mss */
+ bool tfail; /* send() call is expected to fail */
+ int gso_len; /* mss after applying gso */
+ int r_num_mss; /* recv(): number of calls of full mss */
+ int r_len_last; /* recv(): size of last non-mss dgram, if any */
+};
+
+const struct in6_addr addr6 = IN6ADDR_LOOPBACK_INIT;
+const struct in_addr addr4 = { .s_addr = __constant_htonl(INADDR_LOOPBACK + 2) };
+
+struct testcase testcases_v4[] = {
+ {
+ /* no GSO: send a single byte */
+ .tlen = 1,
+ .r_len_last = 1,
+ },
+ {
+ /* no GSO: send a single MSS */
+ .tlen = CONST_MSS_V4,
+ .r_num_mss = 1,
+ },
+ {
+ /* no GSO: send a single MSS + 1B: fail */
+ .tlen = CONST_MSS_V4 + 1,
+ .tfail = true,
+ },
+ {
+ /* send a single MSS: will fail with GSO, because the segment
+ * logic in udp4_ufo_fragment demands a gso skb to be > MTU
+ */
+ .tlen = CONST_MSS_V4,
+ .gso_len = CONST_MSS_V4,
+ .tfail = true,
+ .r_num_mss = 1,
+ },
+ {
+ /* send a single MSS + 1B */
+ .tlen = CONST_MSS_V4 + 1,
+ .gso_len = CONST_MSS_V4,
+ .r_num_mss = 1,
+ .r_len_last = 1,
+ },
+ {
+ /* send exactly 2 MSS */
+ .tlen = CONST_MSS_V4 * 2,
+ .gso_len = CONST_MSS_V4,
+ .r_num_mss = 2,
+ },
+ {
+ /* send 2 MSS + 1B */
+ .tlen = (CONST_MSS_V4 * 2) + 1,
+ .gso_len = CONST_MSS_V4,
+ .r_num_mss = 2,
+ .r_len_last = 1,
+ },
+ {
+ /* send MAX segs */
+ .tlen = (ETH_MAX_MTU / CONST_MSS_V4) * CONST_MSS_V4,
+ .gso_len = CONST_MSS_V4,
+ .r_num_mss = (ETH_MAX_MTU / CONST_MSS_V4),
+ },
+
+ {
+ /* send MAX bytes */
+ .tlen = ETH_MAX_MTU - CONST_HDRLEN_V4,
+ .gso_len = CONST_MSS_V4,
+ .r_num_mss = CONST_MAX_SEGS_V4,
+ .r_len_last = ETH_MAX_MTU - CONST_HDRLEN_V4 -
+ (CONST_MAX_SEGS_V4 * CONST_MSS_V4),
+ },
+ {
+ /* send MAX + 1: fail */
+ .tlen = ETH_MAX_MTU - CONST_HDRLEN_V4 + 1,
+ .gso_len = CONST_MSS_V4,
+ .tfail = true,
+ },
+ {
+ /* EOL */
+ }
+};
+
+#ifndef IP6_MAX_MTU
+#define IP6_MAX_MTU (ETH_MAX_MTU + sizeof(struct ip6_hdr))
+#endif
+
+struct testcase testcases_v6[] = {
+ {
+ /* no GSO: send a single byte */
+ .tlen = 1,
+ .r_len_last = 1,
+ },
+ {
+ /* no GSO: send a single MSS */
+ .tlen = CONST_MSS_V6,
+ .r_num_mss = 1,
+ },
+ {
+ /* no GSO: send a single MSS + 1B: fail */
+ .tlen = CONST_MSS_V6 + 1,
+ .tfail = true,
+ },
+ {
+ /* send a single MSS: will fail with GSO, because the segment
+ * logic in udp4_ufo_fragment demands a gso skb to be > MTU
+ */
+ .tlen = CONST_MSS_V6,
+ .gso_len = CONST_MSS_V6,
+ .tfail = true,
+ .r_num_mss = 1,
+ },
+ {
+ /* send a single MSS + 1B */
+ .tlen = CONST_MSS_V6 + 1,
+ .gso_len = CONST_MSS_V6,
+ .r_num_mss = 1,
+ .r_len_last = 1,
+ },
+ {
+ /* send exactly 2 MSS */
+ .tlen = CONST_MSS_V6 * 2,
+ .gso_len = CONST_MSS_V6,
+ .r_num_mss = 2,
+ },
+ {
+ /* send 2 MSS + 1B */
+ .tlen = (CONST_MSS_V6 * 2) + 1,
+ .gso_len = CONST_MSS_V6,
+ .r_num_mss = 2,
+ .r_len_last = 1,
+ },
+ {
+ /* send MAX segs */
+ .tlen = (IP6_MAX_MTU / CONST_MSS_V6) * CONST_MSS_V6,
+ .gso_len = CONST_MSS_V6,
+ .r_num_mss = (IP6_MAX_MTU / CONST_MSS_V6),
+ },
+
+ {
+ /* send MAX bytes */
+ .tlen = IP6_MAX_MTU - CONST_HDRLEN_V6,
+ .gso_len = CONST_MSS_V6,
+ .r_num_mss = CONST_MAX_SEGS_V6,
+ .r_len_last = IP6_MAX_MTU - CONST_HDRLEN_V6 -
+ (CONST_MAX_SEGS_V6 * CONST_MSS_V6),
+ },
+ {
+ /* send MAX + 1: fail */
+ .tlen = IP6_MAX_MTU - CONST_HDRLEN_V6 + 1,
+ .gso_len = CONST_MSS_V6,
+ .tfail = true,
+ },
+ {
+ /* EOL */
+ }
+};
+
+static unsigned int get_device_mtu(int fd, const char *ifname)
+{
+ struct ifreq ifr;
+
+ memset(&ifr, 0, sizeof(ifr));
+
+ strcpy(ifr.ifr_name, ifname);
+
+ if (ioctl(fd, SIOCGIFMTU, &ifr))
+ error(1, errno, "ioctl get mtu");
+
+ return ifr.ifr_mtu;
+}
+
+static void __set_device_mtu(int fd, const char *ifname, unsigned int mtu)
+{
+ struct ifreq ifr;
+
+ memset(&ifr, 0, sizeof(ifr));
+
+ ifr.ifr_mtu = mtu;
+ strcpy(ifr.ifr_name, ifname);
+
+ if (ioctl(fd, SIOCSIFMTU, &ifr))
+ error(1, errno, "ioctl set mtu");
+}
+
+static void set_device_mtu(int fd, int mtu)
+{
+ int val;
+
+ val = get_device_mtu(fd, cfg_ifname);
+ fprintf(stderr, "device mtu (orig): %u\n", val);
+
+ __set_device_mtu(fd, cfg_ifname, mtu);
+ val = get_device_mtu(fd, cfg_ifname);
+ if (val != mtu)
+ error(1, 0, "unable to set device mtu to %u\n", val);
+
+ fprintf(stderr, "device mtu (test): %u\n", val);
+}
+
+static void set_pmtu_discover(int fd, bool is_ipv4)
+{
+ int level, name, val;
+
+ if (is_ipv4) {
+ level = SOL_IP;
+ name = IP_MTU_DISCOVER;
+ val = IP_PMTUDISC_DO;
+ } else {
+ level = SOL_IPV6;
+ name = IPV6_MTU_DISCOVER;
+ val = IPV6_PMTUDISC_DO;
+ }
+
+ if (setsockopt(fd, level, name, &val, sizeof(val)))
+ error(1, errno, "setsockopt path mtu");
+}
+
+static bool send_one(int fd, int len, int gso_len,
+ struct sockaddr *addr, socklen_t alen)
+{
+ char control[CMSG_SPACE(sizeof(uint16_t))] = {0};
+ struct msghdr msg = {0};
+ struct iovec iov = {0};
+ struct cmsghdr *cm;
+ int ret;
+
+ iov.iov_base = buf;
+ iov.iov_len = len;
+
+ msg.msg_iov = &iov;
+ msg.msg_iovlen = 1;
+
+ msg.msg_name = addr;
+ msg.msg_namelen = alen;
+
+ if (gso_len && !cfg_do_setsockopt) {
+ msg.msg_control = control;
+ msg.msg_controllen = sizeof(control);
+
+ cm = CMSG_FIRSTHDR(&msg);
+ cm->cmsg_level = SOL_UDP;
+ cm->cmsg_type = UDP_SEGMENT;
+ cm->cmsg_len = CMSG_LEN(sizeof(uint16_t));
+ *((uint16_t *) CMSG_DATA(cm)) = gso_len;
+ }
+
+ ret = sendmsg(fd, &msg, 0);
+ if (ret == -1 && (errno == EMSGSIZE || errno == ENOMEM))
+ return false;
+ if (ret == -1)
+ error(1, errno, "sendmsg");
+ if (ret != len)
+ error(1, 0, "sendto: %d != %u", ret, len);
+
+ return true;
+}
+
+static int recv_one(int fd, int flags)
+{
+ int ret;
+
+ ret = recv(fd, buf, sizeof(buf), flags);
+ if (ret == -1 && errno == EAGAIN && (flags & MSG_DONTWAIT))
+ return 0;
+ if (ret == -1)
+ error(1, errno, "recv");
+
+ return ret;
+}
+
+static void run_one(struct testcase *test, int fdt, int fdr,
+ struct sockaddr *addr, socklen_t alen)
+{
+ int i, ret, val, mss;
+ bool sent;
+
+ fprintf(stderr, "ipv%d tx:%d gso:%d %s\n",
+ addr->sa_family == AF_INET ? 4 : 6,
+ test->tlen, test->gso_len,
+ test->tfail ? "(fail)" : "");
+
+ val = test->gso_len;
+ if (cfg_do_setsockopt) {
+ if (setsockopt(fdt, SOL_UDP, UDP_SEGMENT, &val, sizeof(val)))
+ error(1, errno, "setsockopt udp segment");
+ }
+
+ sent = send_one(fdt, test->tlen, test->gso_len, addr, alen);
+ if (sent && test->tfail)
+ error(1, 0, "send succeeded while expecting failure");
+ if (!sent && !test->tfail)
+ error(1, 0, "send failed while expecting success");
+ if (!sent)
+ return;
+
+ mss = addr->sa_family == AF_INET ? CONST_MSS_V4 : CONST_MSS_V6;
+
+ /* Recv all full MSS datagrams */
+ for (i = 0; i < test->r_num_mss; i++) {
+ ret = recv_one(fdr, 0);
+ if (ret != mss)
+ error(1, 0, "recv.%d: %d != %d", i, ret, mss);
+ }
+
+ /* Recv the non-full last datagram, if tlen was not a multiple of mss */
+ if (test->r_len_last) {
+ ret = recv_one(fdr, 0);
+ if (ret != test->r_len_last)
+ error(1, 0, "recv.%d: %d != %d (last)",
+ i, ret, test->r_len_last);
+ }
+
+ /* Verify received all data */
+ ret = recv_one(fdr, MSG_DONTWAIT);
+ if (ret)
+ error(1, 0, "recv: unexpected datagram");
+}
+
+static void run_all(int fdt, int fdr, struct sockaddr *addr, socklen_t alen)
+{
+ struct testcase *tests, *test;
+
+ tests = addr->sa_family == AF_INET ? testcases_v4 : testcases_v6;
+
+ for (test = tests; test->tlen; test++) {
+ /* if a specific test is given, then skip all others */
+ if (cfg_specific_test_id == -1 ||
+ cfg_specific_test_id == test - tests)
+ run_one(test, fdt, fdr, addr, alen);
+ }
+}
+
+static void run_test(struct sockaddr *addr, socklen_t alen)
+{
+ struct timeval tv = { .tv_usec = 100 * 1000 };
+ int fdr, fdt;
+
+ fdr = socket(addr->sa_family, SOCK_DGRAM, 0);
+ if (fdr == -1)
+ error(1, errno, "socket r");
+
+ if (bind(fdr, addr, alen))
+ error(1, errno, "bind");
+
+ /* Have tests fail quickly instead of hang */
+ if (setsockopt(fdr, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv)))
+ error(1, errno, "setsockopt rcv timeout");
+
+ fdt = socket(addr->sa_family, SOCK_DGRAM, 0);
+ if (fdt == -1)
+ error(1, errno, "socket t");
+
+ /* Do not fragment these datagrams: only succeed if GSO works */
+ set_pmtu_discover(fdt, addr->sa_family == AF_INET);
+
+ if (cfg_do_connectionless) {
+ set_device_mtu(fdt, CONST_MTU_TEST);
+ run_all(fdt, fdr, addr, alen);
+ }
+
+ if (close(fdt))
+ error(1, errno, "close t");
+ if (close(fdr))
+ error(1, errno, "close r");
+}
+
+static void run_test_v4(void)
+{
+ struct sockaddr_in addr = {0};
+
+ addr.sin_family = AF_INET;
+ addr.sin_port = htons(cfg_port);
+ addr.sin_addr = addr4;
+
+ run_test((void *)&addr, sizeof(addr));
+}
+
+static void run_test_v6(void)
+{
+ struct sockaddr_in6 addr = {0};
+
+ addr.sin6_family = AF_INET6;
+ addr.sin6_port = htons(cfg_port);
+ addr.sin6_addr = addr6;
+
+ run_test((void *)&addr, sizeof(addr));
+}
+
+static void parse_opts(int argc, char **argv)
+{
+ int c;
+
+ while ((c = getopt(argc, argv, "46Cst:")) != -1) {
+ switch (c) {
+ case '4':
+ cfg_do_ipv4 = true;
+ break;
+ case '6':
+ cfg_do_ipv6 = true;
+ break;
+ case 'C':
+ cfg_do_connectionless = true;
+ break;
+ case 's':
+ cfg_do_setsockopt = true;
+ break;
+ case 't':
+ cfg_specific_test_id = strtoul(optarg, NULL, 0);
+ break;
+ default:
+ error(1, 0, "%s: parse error", argv[0]);
+ }
+ }
+}
+
+int main(int argc, char **argv)
+{
+ parse_opts(argc, argv);
+
+ if (cfg_do_ipv4)
+ run_test_v4();
+ if (cfg_do_ipv6)
+ run_test_v6();
+
+ fprintf(stderr, "OK\n");
+ return 0;
+}
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