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 <linux/compiler.h>
9 #include <sys/socket.h>
10 #include <netinet/in.h>
11 #include <linux/tcp.h>
12 #include <arpa/inet.h>
13
14 #include <unistd.h>
15 #include <stdlib.h>
16 #include <string.h>
17 #include <errno.h>
18 #include <stdio.h>
19
20 #ifndef IPPROTO_MPTCP
21 #define IPPROTO_MPTCP 262
22 #endif
23
24 #define parse_rtattr_nested(tb, max, rta) \
25 (parse_rtattr_flags((tb), (max), RTA_DATA(rta), RTA_PAYLOAD(rta), \
26 NLA_F_NESTED))
27
28 struct params {
29 __u32 target_token;
30 char subflow_addrs[1024];
31 };
32
33 struct mptcp_info {
34 __u8 mptcpi_subflows;
35 __u8 mptcpi_add_addr_signal;
36 __u8 mptcpi_add_addr_accepted;
37 __u8 mptcpi_subflows_max;
38 __u8 mptcpi_add_addr_signal_max;
39 __u8 mptcpi_add_addr_accepted_max;
40 __u32 mptcpi_flags;
41 __u32 mptcpi_token;
42 __u64 mptcpi_write_seq;
43 __u64 mptcpi_snd_una;
44 __u64 mptcpi_rcv_nxt;
45 __u8 mptcpi_local_addr_used;
46 __u8 mptcpi_local_addr_max;
47 __u8 mptcpi_csum_enabled;
48 __u32 mptcpi_retransmits;
49 __u64 mptcpi_bytes_retrans;
50 __u64 mptcpi_bytes_sent;
51 __u64 mptcpi_bytes_received;
52 __u64 mptcpi_bytes_acked;
53 __u8 mptcpi_subflows_total;
54 __u8 reserved[3];
55 __u32 mptcpi_last_data_sent;
56 __u32 mptcpi_last_data_recv;
57 __u32 mptcpi_last_ack_recv;
58 };
59
60 enum {
61 MPTCP_SUBFLOW_ATTR_UNSPEC,
62 MPTCP_SUBFLOW_ATTR_TOKEN_REM,
63 MPTCP_SUBFLOW_ATTR_TOKEN_LOC,
64 MPTCP_SUBFLOW_ATTR_RELWRITE_SEQ,
65 MPTCP_SUBFLOW_ATTR_MAP_SEQ,
66 MPTCP_SUBFLOW_ATTR_MAP_SFSEQ,
67 MPTCP_SUBFLOW_ATTR_SSN_OFFSET,
68 MPTCP_SUBFLOW_ATTR_MAP_DATALEN,
69 MPTCP_SUBFLOW_ATTR_FLAGS,
70 MPTCP_SUBFLOW_ATTR_ID_REM,
71 MPTCP_SUBFLOW_ATTR_ID_LOC,
72 MPTCP_SUBFLOW_ATTR_PAD,
73
74 __MPTCP_SUBFLOW_ATTR_MAX
75 };
76
77 #define MPTCP_SUBFLOW_ATTR_MAX (__MPTCP_SUBFLOW_ATTR_MAX - 1)
78
79 #define MPTCP_SUBFLOW_FLAG_MCAP_REM _BITUL(0)
80 #define MPTCP_SUBFLOW_FLAG_MCAP_LOC _BITUL(1)
81 #define MPTCP_SUBFLOW_FLAG_JOIN_REM _BITUL(2)
82 #define MPTCP_SUBFLOW_FLAG_JOIN_LOC _BITUL(3)
83 #define MPTCP_SUBFLOW_FLAG_BKUP_REM _BITUL(4)
84 #define MPTCP_SUBFLOW_FLAG_BKUP_LOC _BITUL(5)
85 #define MPTCP_SUBFLOW_FLAG_FULLY_ESTABLISHED _BITUL(6)
86 #define MPTCP_SUBFLOW_FLAG_CONNECTED _BITUL(7)
87 #define MPTCP_SUBFLOW_FLAG_MAPVALID _BITUL(8)
88
89 #define rta_getattr(type, value) (*(type *)RTA_DATA(value))
90
die_perror(const char * msg)91 static void __noreturn die_perror(const char *msg)
92 {
93 perror(msg);
94 exit(1);
95 }
96
die_usage(int r)97 static void die_usage(int r)
98 {
99 fprintf(stderr, "Usage:\n"
100 "mptcp_diag -t <token>\n"
101 "mptcp_diag -s \"<saddr>:<sport> <daddr>:<dport>\"\n");
102 exit(r);
103 }
104
send_query(int fd,struct inet_diag_req_v2 * r,__u32 proto)105 static void send_query(int fd, struct inet_diag_req_v2 *r, __u32 proto)
106 {
107 struct sockaddr_nl nladdr = {
108 .nl_family = AF_NETLINK
109 };
110 struct {
111 struct nlmsghdr nlh;
112 struct inet_diag_req_v2 r;
113 } req = {
114 .nlh = {
115 .nlmsg_len = sizeof(req),
116 .nlmsg_type = SOCK_DIAG_BY_FAMILY,
117 .nlmsg_flags = NLM_F_REQUEST
118 },
119 .r = *r
120 };
121 struct rtattr rta_proto;
122 struct iovec iov[6];
123 int iovlen = 0;
124
125 iov[iovlen++] = (struct iovec) {
126 .iov_base = &req,
127 .iov_len = sizeof(req)
128 };
129
130 if (proto == IPPROTO_MPTCP) {
131 rta_proto.rta_type = INET_DIAG_REQ_PROTOCOL;
132 rta_proto.rta_len = RTA_LENGTH(sizeof(proto));
133
134 iov[iovlen++] = (struct iovec){ &rta_proto, sizeof(rta_proto)};
135 iov[iovlen++] = (struct iovec){ &proto, sizeof(proto)};
136 req.nlh.nlmsg_len += RTA_LENGTH(sizeof(proto));
137 }
138
139 struct msghdr msg = {
140 .msg_name = &nladdr,
141 .msg_namelen = sizeof(nladdr),
142 .msg_iov = iov,
143 .msg_iovlen = iovlen
144 };
145
146 for (;;) {
147 if (sendmsg(fd, &msg, 0) < 0) {
148 if (errno == EINTR)
149 continue;
150 die_perror("sendmsg");
151 }
152 break;
153 }
154 }
155
parse_rtattr_flags(struct rtattr * tb[],int max,struct rtattr * rta,int len,unsigned short flags)156 static void parse_rtattr_flags(struct rtattr *tb[], int max, struct rtattr *rta,
157 int len, unsigned short flags)
158 {
159 unsigned short type;
160
161 memset(tb, 0, sizeof(struct rtattr *) * (max + 1));
162 while (RTA_OK(rta, len)) {
163 type = rta->rta_type & ~flags;
164 if (type <= max && !tb[type])
165 tb[type] = rta;
166 rta = RTA_NEXT(rta, len);
167 }
168 }
169
print_info_msg(struct mptcp_info * info)170 static void print_info_msg(struct mptcp_info *info)
171 {
172 printf("Token & Flags\n");
173 printf("token: %x\n", info->mptcpi_token);
174 printf("flags: %x\n", info->mptcpi_flags);
175 printf("csum_enabled: %u\n", info->mptcpi_csum_enabled);
176
177 printf("\nBasic Info\n");
178 printf("subflows: %u\n", info->mptcpi_subflows);
179 printf("subflows_max: %u\n", info->mptcpi_subflows_max);
180 printf("subflows_total: %u\n", info->mptcpi_subflows_total);
181 printf("local_addr_used: %u\n", info->mptcpi_local_addr_used);
182 printf("local_addr_max: %u\n", info->mptcpi_local_addr_max);
183 printf("add_addr_signal: %u\n", info->mptcpi_add_addr_signal);
184 printf("add_addr_accepted: %u\n", info->mptcpi_add_addr_accepted);
185 printf("add_addr_signal_max: %u\n", info->mptcpi_add_addr_signal_max);
186 printf("add_addr_accepted_max: %u\n", info->mptcpi_add_addr_accepted_max);
187
188 printf("\nTransmission Info\n");
189 printf("write_seq: %llu\n", info->mptcpi_write_seq);
190 printf("snd_una: %llu\n", info->mptcpi_snd_una);
191 printf("rcv_nxt: %llu\n", info->mptcpi_rcv_nxt);
192 printf("last_data_sent: %u\n", info->mptcpi_last_data_sent);
193 printf("last_data_recv: %u\n", info->mptcpi_last_data_recv);
194 printf("last_ack_recv: %u\n", info->mptcpi_last_ack_recv);
195 printf("retransmits: %u\n", info->mptcpi_retransmits);
196 printf("retransmit bytes: %llu\n", info->mptcpi_bytes_retrans);
197 printf("bytes_sent: %llu\n", info->mptcpi_bytes_sent);
198 printf("bytes_received: %llu\n", info->mptcpi_bytes_received);
199 printf("bytes_acked: %llu\n", info->mptcpi_bytes_acked);
200 }
201
202 /*
203 * 'print_subflow_info' is from 'mptcp_subflow_info'
204 * which is a function in 'misc/ss.c' of iproute2.
205 */
print_subflow_info(struct rtattr * tb[])206 static void print_subflow_info(struct rtattr *tb[])
207 {
208 u_int32_t flags = 0;
209
210 printf("It's a mptcp subflow, the subflow info:\n");
211 if (tb[MPTCP_SUBFLOW_ATTR_FLAGS]) {
212 char caps[32 + 1] = { 0 }, *cap = &caps[0];
213
214 flags = rta_getattr(__u32, tb[MPTCP_SUBFLOW_ATTR_FLAGS]);
215
216 if (flags & MPTCP_SUBFLOW_FLAG_MCAP_REM)
217 *cap++ = 'M';
218 if (flags & MPTCP_SUBFLOW_FLAG_MCAP_LOC)
219 *cap++ = 'm';
220 if (flags & MPTCP_SUBFLOW_FLAG_JOIN_REM)
221 *cap++ = 'J';
222 if (flags & MPTCP_SUBFLOW_FLAG_JOIN_LOC)
223 *cap++ = 'j';
224 if (flags & MPTCP_SUBFLOW_FLAG_BKUP_REM)
225 *cap++ = 'B';
226 if (flags & MPTCP_SUBFLOW_FLAG_BKUP_LOC)
227 *cap++ = 'b';
228 if (flags & MPTCP_SUBFLOW_FLAG_FULLY_ESTABLISHED)
229 *cap++ = 'e';
230 if (flags & MPTCP_SUBFLOW_FLAG_CONNECTED)
231 *cap++ = 'c';
232 if (flags & MPTCP_SUBFLOW_FLAG_MAPVALID)
233 *cap++ = 'v';
234
235 if (flags)
236 printf(" flags:%s", caps);
237 }
238 if (tb[MPTCP_SUBFLOW_ATTR_TOKEN_REM] &&
239 tb[MPTCP_SUBFLOW_ATTR_TOKEN_LOC] &&
240 tb[MPTCP_SUBFLOW_ATTR_ID_REM] &&
241 tb[MPTCP_SUBFLOW_ATTR_ID_LOC])
242 printf(" token:%04x(id:%u)/%04x(id:%u)",
243 rta_getattr(__u32, tb[MPTCP_SUBFLOW_ATTR_TOKEN_REM]),
244 rta_getattr(__u8, tb[MPTCP_SUBFLOW_ATTR_ID_REM]),
245 rta_getattr(__u32, tb[MPTCP_SUBFLOW_ATTR_TOKEN_LOC]),
246 rta_getattr(__u8, tb[MPTCP_SUBFLOW_ATTR_ID_LOC]));
247 if (tb[MPTCP_SUBFLOW_ATTR_MAP_SEQ])
248 printf(" seq:%llu",
249 rta_getattr(__u64, tb[MPTCP_SUBFLOW_ATTR_MAP_SEQ]));
250 if (tb[MPTCP_SUBFLOW_ATTR_MAP_SFSEQ])
251 printf(" sfseq:%u",
252 rta_getattr(__u32, tb[MPTCP_SUBFLOW_ATTR_MAP_SFSEQ]));
253 if (tb[MPTCP_SUBFLOW_ATTR_SSN_OFFSET])
254 printf(" ssnoff:%u",
255 rta_getattr(__u32, tb[MPTCP_SUBFLOW_ATTR_SSN_OFFSET]));
256 if (tb[MPTCP_SUBFLOW_ATTR_MAP_DATALEN])
257 printf(" maplen:%u",
258 rta_getattr(__u32, tb[MPTCP_SUBFLOW_ATTR_MAP_DATALEN]));
259 printf("\n");
260 }
261
parse_nlmsg(struct nlmsghdr * nlh,__u32 proto)262 static void parse_nlmsg(struct nlmsghdr *nlh, __u32 proto)
263 {
264 struct inet_diag_msg *r = NLMSG_DATA(nlh);
265 struct rtattr *tb[INET_DIAG_MAX + 1];
266
267 parse_rtattr_flags(tb, INET_DIAG_MAX, (struct rtattr *)(r + 1),
268 nlh->nlmsg_len - NLMSG_LENGTH(sizeof(*r)),
269 NLA_F_NESTED);
270
271 if (proto == IPPROTO_MPTCP && tb[INET_DIAG_INFO]) {
272 int len = RTA_PAYLOAD(tb[INET_DIAG_INFO]);
273 struct mptcp_info *info;
274
275 /* workaround fort older kernels with less fields */
276 if (len < sizeof(*info)) {
277 info = alloca(sizeof(*info));
278 memcpy(info, RTA_DATA(tb[INET_DIAG_INFO]), len);
279 memset((char *)info + len, 0, sizeof(*info) - len);
280 } else {
281 info = RTA_DATA(tb[INET_DIAG_INFO]);
282 }
283 print_info_msg(info);
284 }
285 if (proto == IPPROTO_TCP && tb[INET_DIAG_ULP_INFO]) {
286 struct rtattr *ulpinfo[INET_ULP_INFO_MAX + 1] = { 0 };
287
288 parse_rtattr_nested(ulpinfo, INET_ULP_INFO_MAX,
289 tb[INET_DIAG_ULP_INFO]);
290
291 if (ulpinfo[INET_ULP_INFO_MPTCP]) {
292 struct rtattr *sfinfo[MPTCP_SUBFLOW_ATTR_MAX + 1] = { 0 };
293
294 parse_rtattr_nested(sfinfo, MPTCP_SUBFLOW_ATTR_MAX,
295 ulpinfo[INET_ULP_INFO_MPTCP]);
296 print_subflow_info(sfinfo);
297 } else {
298 printf("It's a normal TCP!\n");
299 }
300 }
301 }
302
recv_nlmsg(int fd,__u32 proto)303 static void recv_nlmsg(int fd, __u32 proto)
304 {
305 char rcv_buff[8192];
306 struct nlmsghdr *nlh = (struct nlmsghdr *)rcv_buff;
307 struct sockaddr_nl rcv_nladdr = {
308 .nl_family = AF_NETLINK
309 };
310 struct iovec rcv_iov = {
311 .iov_base = rcv_buff,
312 .iov_len = sizeof(rcv_buff)
313 };
314 struct msghdr rcv_msg = {
315 .msg_name = &rcv_nladdr,
316 .msg_namelen = sizeof(rcv_nladdr),
317 .msg_iov = &rcv_iov,
318 .msg_iovlen = 1
319 };
320 int len;
321
322 len = recvmsg(fd, &rcv_msg, 0);
323
324 while (NLMSG_OK(nlh, len)) {
325 if (nlh->nlmsg_type == NLMSG_DONE) {
326 printf("NLMSG_DONE\n");
327 break;
328 } else if (nlh->nlmsg_type == NLMSG_ERROR) {
329 struct nlmsgerr *err;
330
331 err = (struct nlmsgerr *)NLMSG_DATA(nlh);
332 printf("Error %d:%s\n",
333 -(err->error), strerror(-(err->error)));
334 break;
335 }
336 parse_nlmsg(nlh, proto);
337 nlh = NLMSG_NEXT(nlh, len);
338 }
339 }
340
get_mptcpinfo(__u32 token)341 static void get_mptcpinfo(__u32 token)
342 {
343 struct inet_diag_req_v2 r = {
344 .sdiag_family = AF_INET,
345 /* Real proto is set via INET_DIAG_REQ_PROTOCOL */
346 .sdiag_protocol = IPPROTO_TCP,
347 .idiag_ext = 1 << (INET_DIAG_INFO - 1),
348 .id.idiag_cookie[0] = token,
349 };
350 __u32 proto = IPPROTO_MPTCP;
351 int fd;
352
353 fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_SOCK_DIAG);
354 if (fd < 0)
355 die_perror("Netlink socket");
356
357 send_query(fd, &r, proto);
358 recv_nlmsg(fd, proto);
359
360 close(fd);
361 }
362
get_subflow_info(char * subflow_addrs)363 static void get_subflow_info(char *subflow_addrs)
364 {
365 struct inet_diag_req_v2 r = {
366 .sdiag_family = AF_INET,
367 .sdiag_protocol = IPPROTO_TCP,
368 .idiag_ext = 1 << (INET_DIAG_INFO - 1),
369 .id.idiag_cookie[0] = INET_DIAG_NOCOOKIE,
370 .id.idiag_cookie[1] = INET_DIAG_NOCOOKIE,
371 };
372 char saddr[64], daddr[64];
373 int sport, dport;
374 int ret;
375 int fd;
376
377 ret = sscanf(subflow_addrs, "%[^:]:%d %[^:]:%d", saddr, &sport, daddr, &dport);
378 if (ret != 4)
379 die_perror("IP PORT Pairs has style problems!");
380
381 printf("%s:%d -> %s:%d\n", saddr, sport, daddr, dport);
382
383 fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_SOCK_DIAG);
384 if (fd < 0)
385 die_perror("Netlink socket");
386
387 r.id.idiag_sport = htons(sport);
388 r.id.idiag_dport = htons(dport);
389
390 inet_pton(AF_INET, saddr, &r.id.idiag_src);
391 inet_pton(AF_INET, daddr, &r.id.idiag_dst);
392 send_query(fd, &r, IPPROTO_TCP);
393 recv_nlmsg(fd, IPPROTO_TCP);
394 }
395
parse_opts(int argc,char ** argv,struct params * p)396 static void parse_opts(int argc, char **argv, struct params *p)
397 {
398 int c;
399
400 if (argc < 2)
401 die_usage(1);
402
403 while ((c = getopt(argc, argv, "ht:s:")) != -1) {
404 switch (c) {
405 case 'h':
406 die_usage(0);
407 break;
408 case 't':
409 sscanf(optarg, "%x", &p->target_token);
410 break;
411 case 's':
412 strncpy(p->subflow_addrs, optarg,
413 sizeof(p->subflow_addrs) - 1);
414 break;
415 default:
416 die_usage(1);
417 break;
418 }
419 }
420 }
421
main(int argc,char * argv[])422 int main(int argc, char *argv[])
423 {
424 struct params p = { 0 };
425
426 parse_opts(argc, argv, &p);
427
428 if (p.target_token)
429 get_mptcpinfo(p.target_token);
430
431 if (p.subflow_addrs[0] != '\0')
432 get_subflow_info(p.subflow_addrs);
433
434 return 0;
435 }
436
437