1 // SPDX-License-Identifier: GPL-2.0
2 /* Copyright (c) 2025, Kylin Software */
3
4 #include <linux/sock_diag.h>
5 #include <linux/rtnetlink.h>
6 #include <linux/inet_diag.h>
7 #include <linux/netlink.h>
8 #include <sys/socket.h>
9 #include <netinet/in.h>
10 #include <linux/tcp.h>
11 #include <arpa/inet.h>
12
13 #include <unistd.h>
14 #include <stdlib.h>
15 #include <string.h>
16 #include <errno.h>
17 #include <stdio.h>
18
19 #ifndef IPPROTO_MPTCP
20 #define IPPROTO_MPTCP 262
21 #endif
22
23 #define parse_rtattr_nested(tb, max, rta) \
24 (parse_rtattr_flags((tb), (max), RTA_DATA(rta), RTA_PAYLOAD(rta), \
25 NLA_F_NESTED))
26
27 struct params {
28 __u32 target_token;
29 char subflow_addrs[1024];
30 };
31
32 struct mptcp_info {
33 __u8 mptcpi_subflows;
34 __u8 mptcpi_add_addr_signal;
35 __u8 mptcpi_add_addr_accepted;
36 __u8 mptcpi_subflows_max;
37 __u8 mptcpi_add_addr_signal_max;
38 __u8 mptcpi_add_addr_accepted_max;
39 __u32 mptcpi_flags;
40 __u32 mptcpi_token;
41 __u64 mptcpi_write_seq;
42 __u64 mptcpi_snd_una;
43 __u64 mptcpi_rcv_nxt;
44 __u8 mptcpi_local_addr_used;
45 __u8 mptcpi_local_addr_max;
46 __u8 mptcpi_csum_enabled;
47 __u32 mptcpi_retransmits;
48 __u64 mptcpi_bytes_retrans;
49 __u64 mptcpi_bytes_sent;
50 __u64 mptcpi_bytes_received;
51 __u64 mptcpi_bytes_acked;
52 __u8 mptcpi_subflows_total;
53 __u8 reserved[3];
54 __u32 mptcpi_last_data_sent;
55 __u32 mptcpi_last_data_recv;
56 __u32 mptcpi_last_ack_recv;
57 };
58
59 enum {
60 MPTCP_SUBFLOW_ATTR_UNSPEC,
61 MPTCP_SUBFLOW_ATTR_TOKEN_REM,
62 MPTCP_SUBFLOW_ATTR_TOKEN_LOC,
63 MPTCP_SUBFLOW_ATTR_RELWRITE_SEQ,
64 MPTCP_SUBFLOW_ATTR_MAP_SEQ,
65 MPTCP_SUBFLOW_ATTR_MAP_SFSEQ,
66 MPTCP_SUBFLOW_ATTR_SSN_OFFSET,
67 MPTCP_SUBFLOW_ATTR_MAP_DATALEN,
68 MPTCP_SUBFLOW_ATTR_FLAGS,
69 MPTCP_SUBFLOW_ATTR_ID_REM,
70 MPTCP_SUBFLOW_ATTR_ID_LOC,
71 MPTCP_SUBFLOW_ATTR_PAD,
72
73 __MPTCP_SUBFLOW_ATTR_MAX
74 };
75
76 #define MPTCP_SUBFLOW_ATTR_MAX (__MPTCP_SUBFLOW_ATTR_MAX - 1)
77
78 #define MPTCP_SUBFLOW_FLAG_MCAP_REM _BITUL(0)
79 #define MPTCP_SUBFLOW_FLAG_MCAP_LOC _BITUL(1)
80 #define MPTCP_SUBFLOW_FLAG_JOIN_REM _BITUL(2)
81 #define MPTCP_SUBFLOW_FLAG_JOIN_LOC _BITUL(3)
82 #define MPTCP_SUBFLOW_FLAG_BKUP_REM _BITUL(4)
83 #define MPTCP_SUBFLOW_FLAG_BKUP_LOC _BITUL(5)
84 #define MPTCP_SUBFLOW_FLAG_FULLY_ESTABLISHED _BITUL(6)
85 #define MPTCP_SUBFLOW_FLAG_CONNECTED _BITUL(7)
86 #define MPTCP_SUBFLOW_FLAG_MAPVALID _BITUL(8)
87
88 #define rta_getattr(type, value) (*(type *)RTA_DATA(value))
89
die_perror(const char * msg)90 static void die_perror(const char *msg)
91 {
92 perror(msg);
93 exit(1);
94 }
95
die_usage(int r)96 static void die_usage(int r)
97 {
98 fprintf(stderr, "Usage:\n"
99 "mptcp_diag -t <token>\n"
100 "mptcp_diag -s \"<saddr>:<sport> <daddr>:<dport>\"\n");
101 exit(r);
102 }
103
send_query(int fd,struct inet_diag_req_v2 * r,__u32 proto)104 static void send_query(int fd, struct inet_diag_req_v2 *r, __u32 proto)
105 {
106 struct sockaddr_nl nladdr = {
107 .nl_family = AF_NETLINK
108 };
109 struct {
110 struct nlmsghdr nlh;
111 struct inet_diag_req_v2 r;
112 } req = {
113 .nlh = {
114 .nlmsg_len = sizeof(req),
115 .nlmsg_type = SOCK_DIAG_BY_FAMILY,
116 .nlmsg_flags = NLM_F_REQUEST
117 },
118 .r = *r
119 };
120 struct rtattr rta_proto;
121 struct iovec iov[6];
122 int iovlen = 0;
123
124 iov[iovlen++] = (struct iovec) {
125 .iov_base = &req,
126 .iov_len = sizeof(req)
127 };
128
129 if (proto == IPPROTO_MPTCP) {
130 rta_proto.rta_type = INET_DIAG_REQ_PROTOCOL;
131 rta_proto.rta_len = RTA_LENGTH(sizeof(proto));
132
133 iov[iovlen++] = (struct iovec){ &rta_proto, sizeof(rta_proto)};
134 iov[iovlen++] = (struct iovec){ &proto, sizeof(proto)};
135 req.nlh.nlmsg_len += RTA_LENGTH(sizeof(proto));
136 }
137
138 struct msghdr msg = {
139 .msg_name = &nladdr,
140 .msg_namelen = sizeof(nladdr),
141 .msg_iov = iov,
142 .msg_iovlen = iovlen
143 };
144
145 for (;;) {
146 if (sendmsg(fd, &msg, 0) < 0) {
147 if (errno == EINTR)
148 continue;
149 die_perror("sendmsg");
150 }
151 break;
152 }
153 }
154
parse_rtattr_flags(struct rtattr * tb[],int max,struct rtattr * rta,int len,unsigned short flags)155 static void parse_rtattr_flags(struct rtattr *tb[], int max, struct rtattr *rta,
156 int len, unsigned short flags)
157 {
158 unsigned short type;
159
160 memset(tb, 0, sizeof(struct rtattr *) * (max + 1));
161 while (RTA_OK(rta, len)) {
162 type = rta->rta_type & ~flags;
163 if (type <= max && !tb[type])
164 tb[type] = rta;
165 rta = RTA_NEXT(rta, len);
166 }
167 }
168
print_info_msg(struct mptcp_info * info)169 static void print_info_msg(struct mptcp_info *info)
170 {
171 printf("Token & Flags\n");
172 printf("token: %x\n", info->mptcpi_token);
173 printf("flags: %x\n", info->mptcpi_flags);
174 printf("csum_enabled: %u\n", info->mptcpi_csum_enabled);
175
176 printf("\nBasic Info\n");
177 printf("subflows: %u\n", info->mptcpi_subflows);
178 printf("subflows_max: %u\n", info->mptcpi_subflows_max);
179 printf("subflows_total: %u\n", info->mptcpi_subflows_total);
180 printf("local_addr_used: %u\n", info->mptcpi_local_addr_used);
181 printf("local_addr_max: %u\n", info->mptcpi_local_addr_max);
182 printf("add_addr_signal: %u\n", info->mptcpi_add_addr_signal);
183 printf("add_addr_accepted: %u\n", info->mptcpi_add_addr_accepted);
184 printf("add_addr_signal_max: %u\n", info->mptcpi_add_addr_signal_max);
185 printf("add_addr_accepted_max: %u\n", info->mptcpi_add_addr_accepted_max);
186
187 printf("\nTransmission Info\n");
188 printf("write_seq: %llu\n", info->mptcpi_write_seq);
189 printf("snd_una: %llu\n", info->mptcpi_snd_una);
190 printf("rcv_nxt: %llu\n", info->mptcpi_rcv_nxt);
191 printf("last_data_sent: %u\n", info->mptcpi_last_data_sent);
192 printf("last_data_recv: %u\n", info->mptcpi_last_data_recv);
193 printf("last_ack_recv: %u\n", info->mptcpi_last_ack_recv);
194 printf("retransmits: %u\n", info->mptcpi_retransmits);
195 printf("retransmit bytes: %llu\n", info->mptcpi_bytes_retrans);
196 printf("bytes_sent: %llu\n", info->mptcpi_bytes_sent);
197 printf("bytes_received: %llu\n", info->mptcpi_bytes_received);
198 printf("bytes_acked: %llu\n", info->mptcpi_bytes_acked);
199 }
200
201 /*
202 * 'print_subflow_info' is from 'mptcp_subflow_info'
203 * which is a function in 'misc/ss.c' of iproute2.
204 */
print_subflow_info(struct rtattr * tb[])205 static void print_subflow_info(struct rtattr *tb[])
206 {
207 u_int32_t flags = 0;
208
209 printf("It's a mptcp subflow, the subflow info:\n");
210 if (tb[MPTCP_SUBFLOW_ATTR_FLAGS]) {
211 char caps[32 + 1] = { 0 }, *cap = &caps[0];
212
213 flags = rta_getattr(__u32, tb[MPTCP_SUBFLOW_ATTR_FLAGS]);
214
215 if (flags & MPTCP_SUBFLOW_FLAG_MCAP_REM)
216 *cap++ = 'M';
217 if (flags & MPTCP_SUBFLOW_FLAG_MCAP_LOC)
218 *cap++ = 'm';
219 if (flags & MPTCP_SUBFLOW_FLAG_JOIN_REM)
220 *cap++ = 'J';
221 if (flags & MPTCP_SUBFLOW_FLAG_JOIN_LOC)
222 *cap++ = 'j';
223 if (flags & MPTCP_SUBFLOW_FLAG_BKUP_REM)
224 *cap++ = 'B';
225 if (flags & MPTCP_SUBFLOW_FLAG_BKUP_LOC)
226 *cap++ = 'b';
227 if (flags & MPTCP_SUBFLOW_FLAG_FULLY_ESTABLISHED)
228 *cap++ = 'e';
229 if (flags & MPTCP_SUBFLOW_FLAG_CONNECTED)
230 *cap++ = 'c';
231 if (flags & MPTCP_SUBFLOW_FLAG_MAPVALID)
232 *cap++ = 'v';
233
234 if (flags)
235 printf(" flags:%s", caps);
236 }
237 if (tb[MPTCP_SUBFLOW_ATTR_TOKEN_REM] &&
238 tb[MPTCP_SUBFLOW_ATTR_TOKEN_LOC] &&
239 tb[MPTCP_SUBFLOW_ATTR_ID_REM] &&
240 tb[MPTCP_SUBFLOW_ATTR_ID_LOC])
241 printf(" token:%04x(id:%u)/%04x(id:%u)",
242 rta_getattr(__u32, tb[MPTCP_SUBFLOW_ATTR_TOKEN_REM]),
243 rta_getattr(__u8, tb[MPTCP_SUBFLOW_ATTR_ID_REM]),
244 rta_getattr(__u32, tb[MPTCP_SUBFLOW_ATTR_TOKEN_LOC]),
245 rta_getattr(__u8, tb[MPTCP_SUBFLOW_ATTR_ID_LOC]));
246 if (tb[MPTCP_SUBFLOW_ATTR_MAP_SEQ])
247 printf(" seq:%llu",
248 rta_getattr(__u64, tb[MPTCP_SUBFLOW_ATTR_MAP_SEQ]));
249 if (tb[MPTCP_SUBFLOW_ATTR_MAP_SFSEQ])
250 printf(" sfseq:%u",
251 rta_getattr(__u32, tb[MPTCP_SUBFLOW_ATTR_MAP_SFSEQ]));
252 if (tb[MPTCP_SUBFLOW_ATTR_SSN_OFFSET])
253 printf(" ssnoff:%u",
254 rta_getattr(__u32, tb[MPTCP_SUBFLOW_ATTR_SSN_OFFSET]));
255 if (tb[MPTCP_SUBFLOW_ATTR_MAP_DATALEN])
256 printf(" maplen:%u",
257 rta_getattr(__u32, tb[MPTCP_SUBFLOW_ATTR_MAP_DATALEN]));
258 printf("\n");
259 }
260
parse_nlmsg(struct nlmsghdr * nlh,__u32 proto)261 static void parse_nlmsg(struct nlmsghdr *nlh, __u32 proto)
262 {
263 struct inet_diag_msg *r = NLMSG_DATA(nlh);
264 struct rtattr *tb[INET_DIAG_MAX + 1];
265
266 parse_rtattr_flags(tb, INET_DIAG_MAX, (struct rtattr *)(r + 1),
267 nlh->nlmsg_len - NLMSG_LENGTH(sizeof(*r)),
268 NLA_F_NESTED);
269
270 if (proto == IPPROTO_MPTCP && tb[INET_DIAG_INFO]) {
271 int len = RTA_PAYLOAD(tb[INET_DIAG_INFO]);
272 struct mptcp_info *info;
273
274 /* workaround fort older kernels with less fields */
275 if (len < sizeof(*info)) {
276 info = alloca(sizeof(*info));
277 memcpy(info, RTA_DATA(tb[INET_DIAG_INFO]), len);
278 memset((char *)info + len, 0, sizeof(*info) - len);
279 } else {
280 info = RTA_DATA(tb[INET_DIAG_INFO]);
281 }
282 print_info_msg(info);
283 }
284 if (proto == IPPROTO_TCP && tb[INET_DIAG_ULP_INFO]) {
285 struct rtattr *ulpinfo[INET_ULP_INFO_MAX + 1] = { 0 };
286
287 parse_rtattr_nested(ulpinfo, INET_ULP_INFO_MAX,
288 tb[INET_DIAG_ULP_INFO]);
289
290 if (ulpinfo[INET_ULP_INFO_MPTCP]) {
291 struct rtattr *sfinfo[MPTCP_SUBFLOW_ATTR_MAX + 1] = { 0 };
292
293 parse_rtattr_nested(sfinfo, MPTCP_SUBFLOW_ATTR_MAX,
294 ulpinfo[INET_ULP_INFO_MPTCP]);
295 print_subflow_info(sfinfo);
296 } else {
297 printf("It's a normal TCP!\n");
298 }
299 }
300 }
301
recv_nlmsg(int fd,__u32 proto)302 static void recv_nlmsg(int fd, __u32 proto)
303 {
304 char rcv_buff[8192];
305 struct nlmsghdr *nlh = (struct nlmsghdr *)rcv_buff;
306 struct sockaddr_nl rcv_nladdr = {
307 .nl_family = AF_NETLINK
308 };
309 struct iovec rcv_iov = {
310 .iov_base = rcv_buff,
311 .iov_len = sizeof(rcv_buff)
312 };
313 struct msghdr rcv_msg = {
314 .msg_name = &rcv_nladdr,
315 .msg_namelen = sizeof(rcv_nladdr),
316 .msg_iov = &rcv_iov,
317 .msg_iovlen = 1
318 };
319 int len;
320
321 len = recvmsg(fd, &rcv_msg, 0);
322
323 while (NLMSG_OK(nlh, len)) {
324 if (nlh->nlmsg_type == NLMSG_DONE) {
325 printf("NLMSG_DONE\n");
326 break;
327 } else if (nlh->nlmsg_type == NLMSG_ERROR) {
328 struct nlmsgerr *err;
329
330 err = (struct nlmsgerr *)NLMSG_DATA(nlh);
331 printf("Error %d:%s\n",
332 -(err->error), strerror(-(err->error)));
333 break;
334 }
335 parse_nlmsg(nlh, proto);
336 nlh = NLMSG_NEXT(nlh, len);
337 }
338 }
339
get_mptcpinfo(__u32 token)340 static void get_mptcpinfo(__u32 token)
341 {
342 struct inet_diag_req_v2 r = {
343 .sdiag_family = AF_INET,
344 /* Real proto is set via INET_DIAG_REQ_PROTOCOL */
345 .sdiag_protocol = IPPROTO_TCP,
346 .idiag_ext = 1 << (INET_DIAG_INFO - 1),
347 .id.idiag_cookie[0] = token,
348 };
349 __u32 proto = IPPROTO_MPTCP;
350 int fd;
351
352 fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_SOCK_DIAG);
353 if (fd < 0)
354 die_perror("Netlink socket");
355
356 send_query(fd, &r, proto);
357 recv_nlmsg(fd, proto);
358
359 close(fd);
360 }
361
get_subflow_info(char * subflow_addrs)362 static void get_subflow_info(char *subflow_addrs)
363 {
364 struct inet_diag_req_v2 r = {
365 .sdiag_family = AF_INET,
366 .sdiag_protocol = IPPROTO_TCP,
367 .idiag_ext = 1 << (INET_DIAG_INFO - 1),
368 .id.idiag_cookie[0] = INET_DIAG_NOCOOKIE,
369 .id.idiag_cookie[1] = INET_DIAG_NOCOOKIE,
370 };
371 char saddr[64], daddr[64];
372 int sport, dport;
373 int ret;
374 int fd;
375
376 ret = sscanf(subflow_addrs, "%[^:]:%d %[^:]:%d", saddr, &sport, daddr, &dport);
377 if (ret != 4)
378 die_perror("IP PORT Pairs has style problems!");
379
380 printf("%s:%d -> %s:%d\n", saddr, sport, daddr, dport);
381
382 fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_SOCK_DIAG);
383 if (fd < 0)
384 die_perror("Netlink socket");
385
386 r.id.idiag_sport = htons(sport);
387 r.id.idiag_dport = htons(dport);
388
389 inet_pton(AF_INET, saddr, &r.id.idiag_src);
390 inet_pton(AF_INET, daddr, &r.id.idiag_dst);
391 send_query(fd, &r, IPPROTO_TCP);
392 recv_nlmsg(fd, IPPROTO_TCP);
393 }
394
parse_opts(int argc,char ** argv,struct params * p)395 static void parse_opts(int argc, char **argv, struct params *p)
396 {
397 int c;
398
399 if (argc < 2)
400 die_usage(1);
401
402 while ((c = getopt(argc, argv, "ht:s:")) != -1) {
403 switch (c) {
404 case 'h':
405 die_usage(0);
406 break;
407 case 't':
408 sscanf(optarg, "%x", &p->target_token);
409 break;
410 case 's':
411 strncpy(p->subflow_addrs, optarg,
412 sizeof(p->subflow_addrs) - 1);
413 break;
414 default:
415 die_usage(1);
416 break;
417 }
418 }
419 }
420
main(int argc,char * argv[])421 int main(int argc, char *argv[])
422 {
423 struct params p = { 0 };
424
425 parse_opts(argc, argv, &p);
426
427 if (p.target_token)
428 get_mptcpinfo(p.target_token);
429
430 if (p.subflow_addrs[0] != '\0')
431 get_subflow_info(p.subflow_addrs);
432
433 return 0;
434 }
435
436