// SPDX-License-Identifier: GPL-2.0
#define _GNU_SOURCE
#include <arpa/inet.h>
#include <errno.h>
#include <error.h>
#include <linux/in.h>
#include <netinet/ip.h>
#include <netinet/ip6.h>
#include <netinet/udp.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
static bool cfg_do_ipv4;
static bool cfg_do_ipv6;
static bool cfg_verbose;
static bool cfg_overlap;
static bool cfg_permissive;
static unsigned short cfg_port = 9000;
const struct in_addr addr4 = { .s_addr = __constant_htonl(INADDR_LOOPBACK + 2) };
const struct in6_addr addr6 = IN6ADDR_LOOPBACK_INIT;
#define IP4_HLEN (sizeof(struct iphdr))
#define IP6_HLEN (sizeof(struct ip6_hdr))
#define UDP_HLEN (sizeof(struct udphdr))
/* IPv6 fragment header lenth. */
#define FRAG_HLEN 8
static int payload_len;
static int max_frag_len;
#define MSG_LEN_MAX 10000 /* Max UDP payload length. */
#define IP4_MF (1u << 13) /* IPv4 MF flag. */
#define IP6_MF (1) /* IPv6 MF flag. */
#define CSUM_MANGLED_0 (0xffff)
static uint8_t udp_payload[MSG_LEN_MAX];
static uint8_t ip_frame[IP_MAXPACKET];
static uint32_t ip_id = 0xabcd;
static int msg_counter;
static int frag_counter;
static unsigned int seed;
/* Receive a UDP packet. Validate it matches udp_payload. */
static void recv_validate_udp(int fd_udp)
{
ssize_t ret;
static uint8_t recv_buff[MSG_LEN_MAX];
ret = recv(fd_udp, recv_buff, payload_len, 0);
msg_counter++;
if (cfg_overlap) {
if (ret == -1 && (errno == ETIMEDOUT || errno == EAGAIN))
return; /* OK */
if (!cfg_permissive) {
if (ret != -1)
error(1, 0, "recv: expected timeout; got %d",
(int)ret);
error(1, errno, "recv: expected timeout: %d", errno);
}
}
if (ret == -1)
error(1, errno, "recv: payload_len = %d max_frag_len = %d",
payload_len, max_frag_len);
if (ret != payload_len)
error(1, 0, "recv: wrong size: %d vs %d", (int)ret, payload_len);
if (memcmp(udp_payload, recv_buff, payload_len))
error(1, 0, "recv: wrong data");
}
static uint32_t raw_checksum(uint8_t *buf, int len, uint32_t sum)
{
int i;
for (i = 0; i < (len & ~1U); i += 2) {
sum += (u_int16_t)ntohs(*((u_int16_t *)(buf + i)));
if (sum > 0xffff)
sum -= 0xffff;
}
if (i < len) {
sum += buf[i] << 8;
if (sum > 0xffff)
sum -= 0xffff;
}
return sum;
}
static uint16_t udp_checksum(struct ip *iphdr, struct udphdr *udphdr)
{
uint32_t sum = 0;
uint16_t res;
sum = raw_checksum((uint8_t *)&iphdr->ip_src, 2 * sizeof(iphdr->ip_src),
IPPROTO_UDP + (uint32_t)(UDP_HLEN + payload_len));
sum = raw_checksum((uint8_t *)udphdr, UDP_HLEN, sum);
sum = raw_checksum((uint8_t *)udp_payload, payload_len, sum);
res = 0xffff & ~sum;
if (res)
return htons(res);
else
return CSUM_MANGLED_0;
}
static uint16_t udp6_checksum(struct ip6_hdr *iphdr, struct udphdr *udphdr)
{
uint32_t sum = 0;
uint16_t res;
sum = raw_checksum((uint8_t *)&iphdr->ip6_src, 2 * sizeof(iphdr->ip6_src),
IPPROTO_UDP);
sum = raw_checksum((uint8_t *)&udphdr->len, sizeof(udphdr->len), sum);
sum = raw_checksum((uint8_t *)udphdr, UDP_HLEN, sum);
sum = raw_checksum((uint8_t *)udp_payload, payload_len, sum);
res = 0xffff & ~sum;
if (res)
return htons(res);
else
return CSUM_MANGLED_0;
}
static void send_fragment(int fd_raw, struct sockaddr *addr, socklen_t alen,
int offset, bool ipv6)
{
int frag_len;
int res;
int payload_offset = offset > 0 ? offset - UDP_HLEN : 0;
uint8_t *frag_start = ipv6 ? ip_frame + IP6_HLEN + FRAG_HLEN :
ip_frame + IP4_HLEN;
if (offset == 0) {
struct udphdr udphdr;
udphdr.source = htons(cfg_port + 1);
udphdr.dest = htons(cfg_port);
udphdr.len = htons(UDP_HLEN + payload_len);
udphdr.check = 0;
if (ipv6)
udphdr.check = udp6_checksum((struct ip6_hdr *)ip_frame, &udphdr);
else
udphdr.check = udp_checksum((struct ip *)ip_frame, &udphdr);
memcpy(frag_start, &udphdr, UDP_HLEN);
}
if (ipv6) {
struct ip6_hdr *ip6hdr = (struct ip6_hdr *)ip_frame;
struct ip6_frag *fraghdr = (struct ip6_frag *)(ip_frame + IP6_HLEN);
if (payload_len - payload_offset <= max_frag_len && offset > 0) {
/* This is the last fragment. */
frag_len = FRAG_HLEN + payload_len - payload_offset;
fraghdr->ip6f_offlg = htons(offset);
} else {
frag_len = FRAG_HLEN + max_frag_len;
fraghdr->ip6f_offlg = htons(offset | IP6_MF);
}
ip6hdr->ip6_plen = htons(frag_len);
if (offset == 0)
memcpy(frag_start + UDP_HLEN, udp_payload,
frag_len - FRAG_HLEN - UDP_HLEN);
else
memcpy(frag_start, udp_payload + payload_offset,
frag_len - FRAG_HLEN);
frag_len += IP6_HLEN;
} else {
struct ip *iphdr = (struct ip *)ip_frame;
if (payload_len - payload_offset <= max_frag_len && offset > 0) {
/* This is the last fragment. */
frag_len = IP4_HLEN + payload_len - payload_offset;
iphdr->ip_off = htons(offset / 8);
} else {
frag_len = IP4_HLEN + max_frag_len;
iphdr->ip_off = htons(offset / 8 | IP4_MF);
}
iphdr->ip_len = htons(frag_len);
if (offset == 0)
memcpy(frag_start + UDP_HLEN, udp_payload,
frag_len - IP4_HLEN - UDP_HLEN);
else
memcpy(frag_start, udp_payload + payload_offset,
frag_len - IP4_HLEN);
}
res = sendto(fd_raw, ip_frame, frag_len, 0, addr, alen);
if (res < 0 && errno != EPERM)
error(1, errno, "send_fragment");
if (res >= 0 && res != frag_len)
error(1, 0, "send_fragment: %d vs %d", res, frag_len);
frag_counter++;
}
static void send_udp_frags(int fd_raw, struct sockaddr *addr,
socklen_t alen, bool ipv6)
{
struct ip *iphdr = (struct ip *)ip_frame;
struct ip6_hdr *ip6hdr = (struct ip6_hdr *)ip_frame;
int res;
int offset;
int frag_len;
/* Send the UDP datagram using raw IP fragments: the 0th fragment
* has the UDP header; other fragments are pieces of udp_payload
* split in chunks of frag_len size.
*
* Odd fragments (1st, 3rd, 5th, etc.) are sent out first, then
* even fragments (0th, 2nd, etc.) are sent out.
*/
if (ipv6) {
struct ip6_frag *fraghdr = (struct ip6_frag *)(ip_frame + IP6_HLEN);
((struct sockaddr_in6 *)addr)->sin6_port = 0;
memset(ip6hdr, 0, sizeof(*ip6hdr));
ip6hdr->ip6_flow = htonl(6<<28); /* Version. */
ip6hdr->ip6_nxt = IPPROTO_FRAGMENT;
ip6hdr->ip6_hops = 255;
ip6hdr->ip6_src = addr6;
ip6hdr->ip6_dst = addr6;
fraghdr->ip6f_nxt = IPPROTO_UDP;
fraghdr->ip6f_reserved = 0;
fraghdr->ip6f_ident = htonl(ip_id++);
} else {
memset(iphdr, 0, sizeof(*iphdr));
iphdr->ip_hl = 5;
iphdr->ip_v = 4;
iphdr->ip_tos = 0;
iphdr->ip_id = htons(ip_id++);
iphdr->ip_ttl = 0x40;
iphdr->ip_p = IPPROTO_UDP;
iphdr->ip_src.s_addr = htonl(INADDR_LOOPBACK);
iphdr->ip_dst = addr4;
iphdr->ip_sum = 0;
}
/* Occasionally test in-order fragments. */
if (!cfg_overlap && (rand() % 100 < 15)) {
offset = 0;
while (offset < (UDP_HLEN + payload_len)) {
send_fragment(fd_raw, addr, alen, offset, ipv6);
offset += max_frag_len;
}
return;
}
/* Occasionally test IPv4 "runs" (see net/ipv4/ip_fragment.c) */
if (!cfg_overlap && (rand() % 100 < 20) &&
(payload_len > 9 * max_frag_len)) {
offset = 6 * max_frag_len;
while (offset < (UDP_HLEN + payload_len)) {
send_fragment(fd_raw, addr, alen, offset, ipv6);
offset += max_frag_len;
}
offset = 3 * max_frag_len;
while (offset < 6 * max_frag_len) {
send_fragment(fd_raw, addr, alen, offset, ipv6);
offset += max_frag_len;
}
offset = 0;
while (offset < 3 * max_frag_len) {
send_fragment(fd_raw, addr, alen, offset, ipv6);
offset += max_frag_len;
}
return;
}
/* Odd fragments. */
offset = max_frag_len;
while (offset < (UDP_HLEN + payload_len)) {
send_fragment(fd_raw, addr, alen, offset, ipv6);
/* IPv4 ignores duplicates, so randomly send a duplicate. */
if (rand() % 100 == 1)
send_fragment(fd_raw, addr, alen, offset, ipv6);
offset += 2 * max_frag_len;
}
if (cfg_overlap) {
/* Send an extra random fragment.
*
* Duplicates and some fragments completely inside
* previously sent fragments are dropped/ignored. So
* random offset and frag_len can result in a dropped
* fragment instead of a dropped queue/packet. Thus we
* hard-code offset and frag_len.
*/
if (max_frag_len * 4 < payload_len || max_frag_len < 16) {
/* not enough payload for random offset and frag_len. */
offset = 8;
frag_len = UDP_HLEN + max_frag_len;
} else {
offset = rand() % (payload_len / 2);
frag_len = 2 * max_frag_len + 1 + rand() % 256;
}
if (ipv6) {
struct ip6_frag *fraghdr = (struct ip6_frag *)(ip_frame + IP6_HLEN);
/* sendto() returns EINVAL if offset + frag_len is too small. */
/* In IPv6 if !!(frag_len % 8), the fragment is dropped. */
frag_len &= ~0x7;
fraghdr->ip6f_offlg = htons(offset / 8 | IP6_MF);
ip6hdr->ip6_plen = htons(frag_len);
frag_len += IP6_HLEN;
} else {
frag_len += IP4_HLEN;
iphdr->ip_off = htons(offset / 8 | IP4_MF);
iphdr->ip_len = htons(frag_len);
}
res = sendto(fd_raw, ip_frame, frag_len, 0, addr, alen);
if (res < 0 && errno != EPERM)
error(1, errno, "sendto overlap: %d", frag_len);
if (res >= 0 && res != frag_len)
error(1, 0, "sendto overlap: %d vs %d", (int)res, frag_len);
frag_counter++;
}
/* Event fragments. */
offset = 0;
while (offset < (UDP_HLEN + payload_len)) {
send_fragment(fd_raw, addr, alen, offset, ipv6);
/* IPv4 ignores duplicates, so randomly send a duplicate. */
if (rand() % 100 == 1)
send_fragment(fd_raw, addr, alen, offset, ipv6);
offset += 2 * max_frag_len;
}
}
static void run_test(struct sockaddr *addr, socklen_t alen, bool ipv6)
{
int fd_tx_raw, fd_rx_udp;
/* Frag queue timeout is set to one second in the calling script;
* socket timeout should be just a bit longer to avoid tests interfering
* with each other.
*/
struct timeval tv = { .tv_sec = 1, .tv_usec = 10 };
int idx;
int min_frag_len = 8;
/* Initialize the payload. */
for (idx = 0; idx < MSG_LEN_MAX; ++idx)
udp_payload[idx] = idx % 256;
/* Open sockets. */
fd_tx_raw = socket(addr->sa_family, SOCK_RAW, IPPROTO_RAW);
if (fd_tx_raw == -1)
error(1, errno, "socket tx_raw");
fd_rx_udp = socket(addr->sa_family, SOCK_DGRAM, 0);
if (fd_rx_udp == -1)
error(1, errno, "socket rx_udp");
if (bind(fd_rx_udp, addr, alen))
error(1, errno, "bind");
/* Fail fast. */
if (setsockopt(fd_rx_udp, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv)))
error(1, errno, "setsockopt rcv timeout");
for (payload_len = min_frag_len; payload_len < MSG_LEN_MAX;
payload_len += (rand() % 4096)) {
if (cfg_verbose)
printf("payload_len: %d\n", payload_len);
if (cfg_overlap) {
/* With overlaps, one send/receive pair below takes
* at least one second (== timeout) to run, so there
* is not enough test time to run a nested loop:
* the full overlap test takes 20-30 seconds.
*/
max_frag_len = min_frag_len +
rand() % (1500 - FRAG_HLEN - min_frag_len);
send_udp_frags(fd_tx_raw, addr, alen, ipv6);
recv_validate_udp(fd_rx_udp);
} else {
/* Without overlaps, each packet reassembly (== one
* send/receive pair below) takes very little time to
* run, so we can easily afford more thourough testing
* with a nested loop: the full non-overlap test takes
* less than one second).
*/
max_frag_len = min_frag_len;
do {
send_udp_frags(fd_tx_raw, addr, alen, ipv6);
recv_validate_udp(fd_rx_udp);
max_frag_len += 8 * (rand() % 8);
} while (max_frag_len < (1500 - FRAG_HLEN) &&
max_frag_len <= payload_len);
}
}
/* Cleanup. */
if (close(fd_tx_raw))
error(1, errno, "close tx_raw");
if (close(fd_rx_udp))
error(1, errno, "close rx_udp");
if (cfg_verbose)
printf("processed %d messages, %d fragments\n",
msg_counter, frag_counter);
fprintf(stderr, "PASS\n");
}
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), false /* !ipv6 */);
}
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), true /* ipv6 */);
}
static void parse_opts(int argc, char **argv)
{
int c;
while ((c = getopt(argc, argv, "46opv")) != -1) {
switch (c) {
case '4':
cfg_do_ipv4 = true;
break;
case '6':
cfg_do_ipv6 = true;
break;
case 'o':
cfg_overlap = true;
break;
case 'p':
cfg_permissive = true;
break;
case 'v':
cfg_verbose = true;
break;
default:
error(1, 0, "%s: parse error", argv[0]);
}
}
}
int main(int argc, char **argv)
{
parse_opts(argc, argv);
seed = time(NULL);
srand(seed);
/* Print the seed to track/reproduce potential failures. */
printf("seed = %d\n", seed);
if (cfg_do_ipv4)
run_test_v4();
if (cfg_do_ipv6)
run_test_v6();
return 0;
}
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