mptcp_diag.c

  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
 28struct params {
 29	__u32 target_token;
 30	char subflow_addrs[1024];
 31};
 32
 33struct 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
 60enum {
 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
 91static void __noreturn die_perror(const char *msg)
 92{
 93	perror(msg);
 94	exit(1);
 95}
 96
 97static 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
105static 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
156static 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
170static 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 */
206static 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
262static 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
303static 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
341static 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
363static 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
396static 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
422int 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