tools/testing/selftests/net/mptcp/mptcp_diag.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /* Copyright (c) 2025, Kylin Software */

 #include <linux/sock_diag.h>
 #include <linux/rtnetlink.h>
 #include <linux/inet_diag.h>
 #include <linux/netlink.h>
 #include <sys/socket.h>
 #include <netinet/in.h>
 #include <linux/tcp.h>
 #include <arpa/inet.h>

 #include <unistd.h>
 #include <stdlib.h>
 #include <string.h>
 #include <errno.h>
 #include <stdio.h>

 #ifndef IPPROTO_MPTCP
 #define IPPROTO_MPTCP 262
 #endif

 #define parse_rtattr_nested(tb, max, rta) \
 	(parse_rtattr_flags((tb), (max), RTA_DATA(rta), RTA_PAYLOAD(rta), \
 			    NLA_F_NESTED))

 struct params {
 	__u32 target_token;
 	char subflow_addrs[1024];
 };

 struct mptcp_info {
 	__u8	mptcpi_subflows;
 	__u8	mptcpi_add_addr_signal;
 	__u8	mptcpi_add_addr_accepted;
 	__u8	mptcpi_subflows_max;
 	__u8	mptcpi_add_addr_signal_max;
 	__u8	mptcpi_add_addr_accepted_max;
 	__u32	mptcpi_flags;
 	__u32	mptcpi_token;
 	__u64	mptcpi_write_seq;
 	__u64	mptcpi_snd_una;
 	__u64	mptcpi_rcv_nxt;
 	__u8	mptcpi_local_addr_used;
 	__u8	mptcpi_local_addr_max;
 	__u8	mptcpi_csum_enabled;
 	__u32	mptcpi_retransmits;
 	__u64	mptcpi_bytes_retrans;
 	__u64	mptcpi_bytes_sent;
 	__u64	mptcpi_bytes_received;
 	__u64	mptcpi_bytes_acked;
 	__u8	mptcpi_subflows_total;
 	__u8	reserved[3];
 	__u32	mptcpi_last_data_sent;
 	__u32	mptcpi_last_data_recv;
 	__u32	mptcpi_last_ack_recv;
 };

 enum {
 	MPTCP_SUBFLOW_ATTR_UNSPEC,
 	MPTCP_SUBFLOW_ATTR_TOKEN_REM,
 	MPTCP_SUBFLOW_ATTR_TOKEN_LOC,
 	MPTCP_SUBFLOW_ATTR_RELWRITE_SEQ,
 	MPTCP_SUBFLOW_ATTR_MAP_SEQ,
 	MPTCP_SUBFLOW_ATTR_MAP_SFSEQ,
 	MPTCP_SUBFLOW_ATTR_SSN_OFFSET,
 	MPTCP_SUBFLOW_ATTR_MAP_DATALEN,
 	MPTCP_SUBFLOW_ATTR_FLAGS,
 	MPTCP_SUBFLOW_ATTR_ID_REM,
 	MPTCP_SUBFLOW_ATTR_ID_LOC,
 	MPTCP_SUBFLOW_ATTR_PAD,

 	__MPTCP_SUBFLOW_ATTR_MAX
 };

 #define MPTCP_SUBFLOW_ATTR_MAX (__MPTCP_SUBFLOW_ATTR_MAX - 1)

 #define MPTCP_SUBFLOW_FLAG_MCAP_REM		_BITUL(0)
 #define MPTCP_SUBFLOW_FLAG_MCAP_LOC		_BITUL(1)
 #define MPTCP_SUBFLOW_FLAG_JOIN_REM		_BITUL(2)
 #define MPTCP_SUBFLOW_FLAG_JOIN_LOC		_BITUL(3)
 #define MPTCP_SUBFLOW_FLAG_BKUP_REM		_BITUL(4)
 #define MPTCP_SUBFLOW_FLAG_BKUP_LOC		_BITUL(5)
 #define MPTCP_SUBFLOW_FLAG_FULLY_ESTABLISHED	_BITUL(6)
 #define MPTCP_SUBFLOW_FLAG_CONNECTED		_BITUL(7)
 #define MPTCP_SUBFLOW_FLAG_MAPVALID		_BITUL(8)

 #define rta_getattr(type, value)		(*(type *)RTA_DATA(value))

 static void die_perror(const char *msg)
 {
 	perror(msg);
 	exit(1);
 }

 static void die_usage(int r)
 {
 	fprintf(stderr, "Usage:\n"
 			"mptcp_diag -t <token>\n"
 			"mptcp_diag -s \"<saddr>:<sport> <daddr>:<dport>\"\n");
 	exit(r);
 }

 static void send_query(int fd, struct inet_diag_req_v2 *r, __u32 proto)
 {
 	struct sockaddr_nl nladdr = {
 		.nl_family = AF_NETLINK
 	};
 	struct {
 		struct nlmsghdr nlh;
 		struct inet_diag_req_v2 r;
 	} req = {
 		.nlh = {
 			.nlmsg_len = sizeof(req),
 			.nlmsg_type = SOCK_DIAG_BY_FAMILY,
 			.nlmsg_flags = NLM_F_REQUEST
 		},
 		.r = *r
 	};
 	struct rtattr rta_proto;
 	struct iovec iov[6];
 	int iovlen = 0;

 	iov[iovlen++] = (struct iovec) {
 		.iov_base = &req,
 		.iov_len = sizeof(req)
 	};

 	if (proto == IPPROTO_MPTCP) {
 		rta_proto.rta_type = INET_DIAG_REQ_PROTOCOL;
 		rta_proto.rta_len = RTA_LENGTH(sizeof(proto));

 		iov[iovlen++] = (struct iovec){ &rta_proto, sizeof(rta_proto)};
 		iov[iovlen++] = (struct iovec){ &proto, sizeof(proto)};
 		req.nlh.nlmsg_len += RTA_LENGTH(sizeof(proto));
 	}

 	struct msghdr msg = {
 		.msg_name = &nladdr,
 		.msg_namelen = sizeof(nladdr),
 		.msg_iov = iov,
 		.msg_iovlen = iovlen
 	};

 	for (;;) {
 		if (sendmsg(fd, &msg, 0) < 0) {
 			if (errno == EINTR)
 				continue;
 			die_perror("sendmsg");
 		}
 		break;
 	}
 }

 static void parse_rtattr_flags(struct rtattr *tb[], int max, struct rtattr *rta,
 			       int len, unsigned short flags)
 {
 	unsigned short type;

 	memset(tb, 0, sizeof(struct rtattr *) * (max + 1));
 	while (RTA_OK(rta, len)) {
 		type = rta->rta_type & ~flags;
 		if (type <= max && !tb[type])
 			tb[type] = rta;
 		rta = RTA_NEXT(rta, len);
 	}
 }

 static void print_info_msg(struct mptcp_info *info)
 {
 	printf("Token & Flags\n");
 	printf("token:        %x\n", info->mptcpi_token);
 	printf("flags:        %x\n", info->mptcpi_flags);
 	printf("csum_enabled: %u\n", info->mptcpi_csum_enabled);

 	printf("\nBasic Info\n");
 	printf("subflows:              %u\n", info->mptcpi_subflows);
 	printf("subflows_max:          %u\n", info->mptcpi_subflows_max);
 	printf("subflows_total:        %u\n", info->mptcpi_subflows_total);
 	printf("local_addr_used:       %u\n", info->mptcpi_local_addr_used);
 	printf("local_addr_max:        %u\n", info->mptcpi_local_addr_max);
 	printf("add_addr_signal:       %u\n", info->mptcpi_add_addr_signal);
 	printf("add_addr_accepted:     %u\n", info->mptcpi_add_addr_accepted);
 	printf("add_addr_signal_max:   %u\n", info->mptcpi_add_addr_signal_max);
 	printf("add_addr_accepted_max: %u\n", info->mptcpi_add_addr_accepted_max);

 	printf("\nTransmission Info\n");
 	printf("write_seq:        %llu\n", info->mptcpi_write_seq);
 	printf("snd_una:          %llu\n", info->mptcpi_snd_una);
 	printf("rcv_nxt:          %llu\n", info->mptcpi_rcv_nxt);
 	printf("last_data_sent:   %u\n", info->mptcpi_last_data_sent);
 	printf("last_data_recv:   %u\n", info->mptcpi_last_data_recv);
 	printf("last_ack_recv:    %u\n", info->mptcpi_last_ack_recv);
 	printf("retransmits:      %u\n", info->mptcpi_retransmits);
 	printf("retransmit bytes: %llu\n", info->mptcpi_bytes_retrans);
 	printf("bytes_sent:       %llu\n", info->mptcpi_bytes_sent);
 	printf("bytes_received:   %llu\n", info->mptcpi_bytes_received);
 	printf("bytes_acked:      %llu\n", info->mptcpi_bytes_acked);
 }

 /*
  * 'print_subflow_info' is from 'mptcp_subflow_info'
  * which is a function in 'misc/ss.c' of iproute2.
  */
 static void print_subflow_info(struct rtattr *tb[])
 {
 	u_int32_t flags = 0;

 	printf("It's a mptcp subflow, the subflow info:\n");
 	if (tb[MPTCP_SUBFLOW_ATTR_FLAGS]) {
 		char caps[32 + 1] = { 0 }, *cap = &caps[0];

 		flags = rta_getattr(__u32, tb[MPTCP_SUBFLOW_ATTR_FLAGS]);

 		if (flags & MPTCP_SUBFLOW_FLAG_MCAP_REM)
 			*cap++ = 'M';
 		if (flags & MPTCP_SUBFLOW_FLAG_MCAP_LOC)
 			*cap++ = 'm';
 		if (flags & MPTCP_SUBFLOW_FLAG_JOIN_REM)
 			*cap++ = 'J';
 		if (flags & MPTCP_SUBFLOW_FLAG_JOIN_LOC)
 			*cap++ = 'j';
 		if (flags & MPTCP_SUBFLOW_FLAG_BKUP_REM)
 			*cap++ = 'B';
 		if (flags & MPTCP_SUBFLOW_FLAG_BKUP_LOC)
 			*cap++ = 'b';
 		if (flags & MPTCP_SUBFLOW_FLAG_FULLY_ESTABLISHED)
 			*cap++ = 'e';
 		if (flags & MPTCP_SUBFLOW_FLAG_CONNECTED)
 			*cap++ = 'c';
 		if (flags & MPTCP_SUBFLOW_FLAG_MAPVALID)
 			*cap++ = 'v';

 		if (flags)
 			printf(" flags:%s", caps);
 	}
 	if (tb[MPTCP_SUBFLOW_ATTR_TOKEN_REM] &&
 	    tb[MPTCP_SUBFLOW_ATTR_TOKEN_LOC] &&
 	    tb[MPTCP_SUBFLOW_ATTR_ID_REM] &&
 	    tb[MPTCP_SUBFLOW_ATTR_ID_LOC])
 		printf(" token:%04x(id:%u)/%04x(id:%u)",
 		       rta_getattr(__u32, tb[MPTCP_SUBFLOW_ATTR_TOKEN_REM]),
 		       rta_getattr(__u8, tb[MPTCP_SUBFLOW_ATTR_ID_REM]),
 		       rta_getattr(__u32, tb[MPTCP_SUBFLOW_ATTR_TOKEN_LOC]),
 		       rta_getattr(__u8, tb[MPTCP_SUBFLOW_ATTR_ID_LOC]));
 	if (tb[MPTCP_SUBFLOW_ATTR_MAP_SEQ])
 		printf(" seq:%llu",
 		       rta_getattr(__u64, tb[MPTCP_SUBFLOW_ATTR_MAP_SEQ]));
 	if (tb[MPTCP_SUBFLOW_ATTR_MAP_SFSEQ])
 		printf(" sfseq:%u",
 		       rta_getattr(__u32, tb[MPTCP_SUBFLOW_ATTR_MAP_SFSEQ]));
 	if (tb[MPTCP_SUBFLOW_ATTR_SSN_OFFSET])
 		printf(" ssnoff:%u",
 		       rta_getattr(__u32, tb[MPTCP_SUBFLOW_ATTR_SSN_OFFSET]));
 	if (tb[MPTCP_SUBFLOW_ATTR_MAP_DATALEN])
 		printf(" maplen:%u",
 		       rta_getattr(__u32, tb[MPTCP_SUBFLOW_ATTR_MAP_DATALEN]));
 	printf("\n");
 }

 static void parse_nlmsg(struct nlmsghdr *nlh, __u32 proto)
 {
 	struct inet_diag_msg *r = NLMSG_DATA(nlh);
 	struct rtattr *tb[INET_DIAG_MAX + 1];

 	parse_rtattr_flags(tb, INET_DIAG_MAX, (struct rtattr *)(r + 1),
 			   nlh->nlmsg_len - NLMSG_LENGTH(sizeof(*r)),
 			   NLA_F_NESTED);

 	if (proto == IPPROTO_MPTCP && tb[INET_DIAG_INFO]) {
 		int len = RTA_PAYLOAD(tb[INET_DIAG_INFO]);
 		struct mptcp_info *info;

 		/* workaround fort older kernels with less fields */
 		if (len < sizeof(*info)) {
 			info = alloca(sizeof(*info));
 			memcpy(info, RTA_DATA(tb[INET_DIAG_INFO]), len);
 			memset((char *)info + len, 0, sizeof(*info) - len);
 		} else {
 			info = RTA_DATA(tb[INET_DIAG_INFO]);
 		}
 		print_info_msg(info);
 	}
 	if (proto == IPPROTO_TCP && tb[INET_DIAG_ULP_INFO]) {
 		struct rtattr *ulpinfo[INET_ULP_INFO_MAX + 1] = { 0 };

 		parse_rtattr_nested(ulpinfo, INET_ULP_INFO_MAX,
 				    tb[INET_DIAG_ULP_INFO]);

 		if (ulpinfo[INET_ULP_INFO_MPTCP]) {
 			struct rtattr *sfinfo[MPTCP_SUBFLOW_ATTR_MAX + 1] = { 0 };

 			parse_rtattr_nested(sfinfo, MPTCP_SUBFLOW_ATTR_MAX,
 					    ulpinfo[INET_ULP_INFO_MPTCP]);
 			print_subflow_info(sfinfo);
 		} else {
 			printf("It's a normal TCP!\n");
 		}
 	}
 }

 static void recv_nlmsg(int fd, __u32 proto)
 {
 	char rcv_buff[8192];
 	struct nlmsghdr *nlh = (struct nlmsghdr *)rcv_buff;
 	struct sockaddr_nl rcv_nladdr = {
 		.nl_family = AF_NETLINK
 	};
 	struct iovec rcv_iov = {
 		.iov_base = rcv_buff,
 		.iov_len = sizeof(rcv_buff)
 	};
 	struct msghdr rcv_msg = {
 		.msg_name = &rcv_nladdr,
 		.msg_namelen = sizeof(rcv_nladdr),
 		.msg_iov = &rcv_iov,
 		.msg_iovlen = 1
 	};
 	int len;

 	len = recvmsg(fd, &rcv_msg, 0);

 	while (NLMSG_OK(nlh, len)) {
 		if (nlh->nlmsg_type == NLMSG_DONE) {
 			printf("NLMSG_DONE\n");
 			break;
 		} else if (nlh->nlmsg_type == NLMSG_ERROR) {
 			struct nlmsgerr *err;

 			err = (struct nlmsgerr *)NLMSG_DATA(nlh);
 			printf("Error %d:%s\n",
 			       -(err->error), strerror(-(err->error)));
 			break;
 		}
 		parse_nlmsg(nlh, proto);
 		nlh = NLMSG_NEXT(nlh, len);
 	}
 }

 static void get_mptcpinfo(__u32 token)
 {
 	struct inet_diag_req_v2 r = {
 		.sdiag_family           = AF_INET,
 		/* Real proto is set via INET_DIAG_REQ_PROTOCOL */
 		.sdiag_protocol         = IPPROTO_TCP,
 		.idiag_ext              = 1 << (INET_DIAG_INFO - 1),
 		.id.idiag_cookie[0]     = token,
 	};
 	__u32 proto = IPPROTO_MPTCP;
 	int fd;

 	fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_SOCK_DIAG);
 	if (fd < 0)
 		die_perror("Netlink socket");

 	send_query(fd, &r, proto);
 	recv_nlmsg(fd, proto);

 	close(fd);
 }

 static void get_subflow_info(char *subflow_addrs)
 {
 	struct inet_diag_req_v2 r = {
 		.sdiag_family           = AF_INET,
 		.sdiag_protocol         = IPPROTO_TCP,
 		.idiag_ext              = 1 << (INET_DIAG_INFO - 1),
 		.id.idiag_cookie[0]     = INET_DIAG_NOCOOKIE,
 		.id.idiag_cookie[1]     = INET_DIAG_NOCOOKIE,
 	};
 	char saddr[64], daddr[64];
 	int sport, dport;
 	int ret;
 	int fd;

 	ret = sscanf(subflow_addrs, "%[^:]:%d %[^:]:%d", saddr, &sport, daddr, &dport);
 	if (ret != 4)
 		die_perror("IP PORT Pairs has style problems!");

 	printf("%s:%d -> %s:%d\n", saddr, sport, daddr, dport);

 	fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_SOCK_DIAG);
 	if (fd < 0)
 		die_perror("Netlink socket");

 	r.id.idiag_sport = htons(sport);
 	r.id.idiag_dport = htons(dport);

 	inet_pton(AF_INET, saddr, &r.id.idiag_src);
 	inet_pton(AF_INET, daddr, &r.id.idiag_dst);
 	send_query(fd, &r, IPPROTO_TCP);
 	recv_nlmsg(fd, IPPROTO_TCP);
 }

 static void parse_opts(int argc, char **argv, struct params *p)
 {
 	int c;

 	if (argc < 2)
 		die_usage(1);

 	while ((c = getopt(argc, argv, "ht:s:")) != -1) {
 		switch (c) {
 		case 'h':
 			die_usage(0);
 			break;
 		case 't':
 			sscanf(optarg, "%x", &p->target_token);
 			break;
 		case 's':
 			strncpy(p->subflow_addrs, optarg,
 				sizeof(p->subflow_addrs) - 1);
 			break;
 		default:
 			die_usage(1);
 			break;
 		}
 	}
 }

 int main(int argc, char *argv[])
 {
 	struct params p = { 0 };

 	parse_opts(argc, argv, &p);

 	if (p.target_token)
 		get_mptcpinfo(p.target_token);

 	if (p.subflow_addrs[0] != '\0')
 		get_subflow_info(p.subflow_addrs);

 	return 0;
 }
	// SPDX-License-Identifier: GPL-2.0
	/* Copyright (c) 2025, Kylin Software */

	#include <linux/sock_diag.h>
	#include <linux/rtnetlink.h>
	#include <linux/inet_diag.h>
	#include <linux/netlink.h>
	#include <sys/socket.h>
	#include <netinet/in.h>
	#include <linux/tcp.h>
	#include <arpa/inet.h>

	#include <unistd.h>
	#include <stdlib.h>
	#include <string.h>
	#include <errno.h>
	#include <stdio.h>

	#ifndef IPPROTO_MPTCP
	#define IPPROTO_MPTCP 262
	#endif

	#define parse_rtattr_nested(tb, max, rta) \
	(parse_rtattr_flags((tb), (max), RTA_DATA(rta), RTA_PAYLOAD(rta), \
	NLA_F_NESTED))

	struct params {
	__u32 target_token;
	char subflow_addrs[1024];
	};

	struct mptcp_info {
	__u8 mptcpi_subflows;
	__u8 mptcpi_add_addr_signal;
	__u8 mptcpi_add_addr_accepted;
	__u8 mptcpi_subflows_max;
	__u8 mptcpi_add_addr_signal_max;
	__u8 mptcpi_add_addr_accepted_max;
	__u32 mptcpi_flags;
	__u32 mptcpi_token;
	__u64 mptcpi_write_seq;
	__u64 mptcpi_snd_una;
	__u64 mptcpi_rcv_nxt;
	__u8 mptcpi_local_addr_used;
	__u8 mptcpi_local_addr_max;
	__u8 mptcpi_csum_enabled;
	__u32 mptcpi_retransmits;
	__u64 mptcpi_bytes_retrans;
	__u64 mptcpi_bytes_sent;
	__u64 mptcpi_bytes_received;
	__u64 mptcpi_bytes_acked;
	__u8 mptcpi_subflows_total;
	__u8 reserved[3];
	__u32 mptcpi_last_data_sent;
	__u32 mptcpi_last_data_recv;
	__u32 mptcpi_last_ack_recv;
	};

	enum {
	MPTCP_SUBFLOW_ATTR_UNSPEC,
	MPTCP_SUBFLOW_ATTR_TOKEN_REM,
	MPTCP_SUBFLOW_ATTR_TOKEN_LOC,
	MPTCP_SUBFLOW_ATTR_RELWRITE_SEQ,
	MPTCP_SUBFLOW_ATTR_MAP_SEQ,
	MPTCP_SUBFLOW_ATTR_MAP_SFSEQ,
	MPTCP_SUBFLOW_ATTR_SSN_OFFSET,
	MPTCP_SUBFLOW_ATTR_MAP_DATALEN,
	MPTCP_SUBFLOW_ATTR_FLAGS,
	MPTCP_SUBFLOW_ATTR_ID_REM,
	MPTCP_SUBFLOW_ATTR_ID_LOC,
	MPTCP_SUBFLOW_ATTR_PAD,

	__MPTCP_SUBFLOW_ATTR_MAX
	};

	#define MPTCP_SUBFLOW_ATTR_MAX (__MPTCP_SUBFLOW_ATTR_MAX - 1)

	#define MPTCP_SUBFLOW_FLAG_MCAP_REM _BITUL(0)
	#define MPTCP_SUBFLOW_FLAG_MCAP_LOC _BITUL(1)
	#define MPTCP_SUBFLOW_FLAG_JOIN_REM _BITUL(2)
	#define MPTCP_SUBFLOW_FLAG_JOIN_LOC _BITUL(3)
	#define MPTCP_SUBFLOW_FLAG_BKUP_REM _BITUL(4)
	#define MPTCP_SUBFLOW_FLAG_BKUP_LOC _BITUL(5)
	#define MPTCP_SUBFLOW_FLAG_FULLY_ESTABLISHED _BITUL(6)
	#define MPTCP_SUBFLOW_FLAG_CONNECTED _BITUL(7)
	#define MPTCP_SUBFLOW_FLAG_MAPVALID _BITUL(8)

	#define rta_getattr(type, value) ((type )RTA_DATA(value))

	static void die_perror(const char *msg)
	{
	perror(msg);
	exit(1);
	}

	static void die_usage(int r)
	{
	fprintf(stderr, "Usage:\n"
	"mptcp_diag -t <token>\n"
	"mptcp_diag -s \"<saddr>:<sport> <daddr>:<dport>\"\n");
	exit(r);
	}

	static void send_query(int fd, struct inet_diag_req_v2 *r, __u32 proto)
	{
	struct sockaddr_nl nladdr = {
	.nl_family = AF_NETLINK
	};
	struct {
	struct nlmsghdr nlh;
	struct inet_diag_req_v2 r;
	} req = {
	.nlh = {
	.nlmsg_len = sizeof(req),
	.nlmsg_type = SOCK_DIAG_BY_FAMILY,
	.nlmsg_flags = NLM_F_REQUEST
	},
	.r = *r
	};
	struct rtattr rta_proto;
	struct iovec iov[6];
	int iovlen = 0;

	iov[iovlen++] = (struct iovec) {
	.iov_base = &req,
	.iov_len = sizeof(req)
	};

	if (proto == IPPROTO_MPTCP) {
	rta_proto.rta_type = INET_DIAG_REQ_PROTOCOL;
	rta_proto.rta_len = RTA_LENGTH(sizeof(proto));

	iov[iovlen++] = (struct iovec){ &rta_proto, sizeof(rta_proto)};
	iov[iovlen++] = (struct iovec){ &proto, sizeof(proto)};
	req.nlh.nlmsg_len += RTA_LENGTH(sizeof(proto));
	}

	struct msghdr msg = {
	.msg_name = &nladdr,
	.msg_namelen = sizeof(nladdr),
	.msg_iov = iov,
	.msg_iovlen = iovlen
	};

	for (;;) {
	if (sendmsg(fd, &msg, 0) < 0) {
	if (errno == EINTR)
	continue;
	die_perror("sendmsg");
	}
	break;
	}
	}

	static void parse_rtattr_flags(struct rtattr tb[], int max, struct rtattr rta,
	int len, unsigned short flags)
	{
	unsigned short type;

	memset(tb, 0, sizeof(struct rtattr ) (max + 1));
	while (RTA_OK(rta, len)) {
	type = rta->rta_type & ~flags;
	if (type <= max && !tb[type])
	tb[type] = rta;
	rta = RTA_NEXT(rta, len);
	}
	}

	static void print_info_msg(struct mptcp_info *info)
	{
	printf("Token & Flags\n");
	printf("token: %x\n", info->mptcpi_token);
	printf("flags: %x\n", info->mptcpi_flags);
	printf("csum_enabled: %u\n", info->mptcpi_csum_enabled);

	printf("\nBasic Info\n");
	printf("subflows: %u\n", info->mptcpi_subflows);
	printf("subflows_max: %u\n", info->mptcpi_subflows_max);
	printf("subflows_total: %u\n", info->mptcpi_subflows_total);
	printf("local_addr_used: %u\n", info->mptcpi_local_addr_used);
	printf("local_addr_max: %u\n", info->mptcpi_local_addr_max);
	printf("add_addr_signal: %u\n", info->mptcpi_add_addr_signal);
	printf("add_addr_accepted: %u\n", info->mptcpi_add_addr_accepted);
	printf("add_addr_signal_max: %u\n", info->mptcpi_add_addr_signal_max);
	printf("add_addr_accepted_max: %u\n", info->mptcpi_add_addr_accepted_max);

	printf("\nTransmission Info\n");
	printf("write_seq: %llu\n", info->mptcpi_write_seq);
	printf("snd_una: %llu\n", info->mptcpi_snd_una);
	printf("rcv_nxt: %llu\n", info->mptcpi_rcv_nxt);
	printf("last_data_sent: %u\n", info->mptcpi_last_data_sent);
	printf("last_data_recv: %u\n", info->mptcpi_last_data_recv);
	printf("last_ack_recv: %u\n", info->mptcpi_last_ack_recv);
	printf("retransmits: %u\n", info->mptcpi_retransmits);
	printf("retransmit bytes: %llu\n", info->mptcpi_bytes_retrans);
	printf("bytes_sent: %llu\n", info->mptcpi_bytes_sent);
	printf("bytes_received: %llu\n", info->mptcpi_bytes_received);
	printf("bytes_acked: %llu\n", info->mptcpi_bytes_acked);
	}

	/*
	* 'print_subflow_info' is from 'mptcp_subflow_info'
	* which is a function in 'misc/ss.c' of iproute2.
	*/
	static void print_subflow_info(struct rtattr *tb[])
	{
	u_int32_t flags = 0;

	printf("It's a mptcp subflow, the subflow info:\n");
	if (tb[MPTCP_SUBFLOW_ATTR_FLAGS]) {
	char caps[32 + 1] = { 0 }, *cap = &caps[0];

	flags = rta_getattr(__u32, tb[MPTCP_SUBFLOW_ATTR_FLAGS]);

	if (flags & MPTCP_SUBFLOW_FLAG_MCAP_REM)
	*cap++ = 'M';
	if (flags & MPTCP_SUBFLOW_FLAG_MCAP_LOC)
	*cap++ = 'm';
	if (flags & MPTCP_SUBFLOW_FLAG_JOIN_REM)
	*cap++ = 'J';
	if (flags & MPTCP_SUBFLOW_FLAG_JOIN_LOC)
	*cap++ = 'j';
	if (flags & MPTCP_SUBFLOW_FLAG_BKUP_REM)
	*cap++ = 'B';
	if (flags & MPTCP_SUBFLOW_FLAG_BKUP_LOC)
	*cap++ = 'b';
	if (flags & MPTCP_SUBFLOW_FLAG_FULLY_ESTABLISHED)
	*cap++ = 'e';
	if (flags & MPTCP_SUBFLOW_FLAG_CONNECTED)
	*cap++ = 'c';
	if (flags & MPTCP_SUBFLOW_FLAG_MAPVALID)
	*cap++ = 'v';

	if (flags)
	printf(" flags:%s", caps);
	}
	if (tb[MPTCP_SUBFLOW_ATTR_TOKEN_REM] &&
	tb[MPTCP_SUBFLOW_ATTR_TOKEN_LOC] &&
	tb[MPTCP_SUBFLOW_ATTR_ID_REM] &&
	tb[MPTCP_SUBFLOW_ATTR_ID_LOC])
	printf(" token:%04x(id:%u)/%04x(id:%u)",
	rta_getattr(__u32, tb[MPTCP_SUBFLOW_ATTR_TOKEN_REM]),
	rta_getattr(__u8, tb[MPTCP_SUBFLOW_ATTR_ID_REM]),
	rta_getattr(__u32, tb[MPTCP_SUBFLOW_ATTR_TOKEN_LOC]),
	rta_getattr(__u8, tb[MPTCP_SUBFLOW_ATTR_ID_LOC]));
	if (tb[MPTCP_SUBFLOW_ATTR_MAP_SEQ])
	printf(" seq:%llu",
	rta_getattr(__u64, tb[MPTCP_SUBFLOW_ATTR_MAP_SEQ]));
	if (tb[MPTCP_SUBFLOW_ATTR_MAP_SFSEQ])
	printf(" sfseq:%u",
	rta_getattr(__u32, tb[MPTCP_SUBFLOW_ATTR_MAP_SFSEQ]));
	if (tb[MPTCP_SUBFLOW_ATTR_SSN_OFFSET])
	printf(" ssnoff:%u",
	rta_getattr(__u32, tb[MPTCP_SUBFLOW_ATTR_SSN_OFFSET]));
	if (tb[MPTCP_SUBFLOW_ATTR_MAP_DATALEN])
	printf(" maplen:%u",
	rta_getattr(__u32, tb[MPTCP_SUBFLOW_ATTR_MAP_DATALEN]));
	printf("\n");
	}

	static void parse_nlmsg(struct nlmsghdr *nlh, __u32 proto)
	{
	struct inet_diag_msg *r = NLMSG_DATA(nlh);
	struct rtattr *tb[INET_DIAG_MAX + 1];

	parse_rtattr_flags(tb, INET_DIAG_MAX, (struct rtattr *)(r + 1),
	nlh->nlmsg_len - NLMSG_LENGTH(sizeof(*r)),
	NLA_F_NESTED);

	if (proto == IPPROTO_MPTCP && tb[INET_DIAG_INFO]) {
	int len = RTA_PAYLOAD(tb[INET_DIAG_INFO]);
	struct mptcp_info *info;

	/* workaround fort older kernels with less fields */
	if (len < sizeof(*info)) {
	info = alloca(sizeof(*info));
	memcpy(info, RTA_DATA(tb[INET_DIAG_INFO]), len);
	memset((char )info + len, 0, sizeof(info) - len);
	} else {
	info = RTA_DATA(tb[INET_DIAG_INFO]);
	}
	print_info_msg(info);
	}
	if (proto == IPPROTO_TCP && tb[INET_DIAG_ULP_INFO]) {
	struct rtattr *ulpinfo[INET_ULP_INFO_MAX + 1] = { 0 };

	parse_rtattr_nested(ulpinfo, INET_ULP_INFO_MAX,
	tb[INET_DIAG_ULP_INFO]);

	if (ulpinfo[INET_ULP_INFO_MPTCP]) {
	struct rtattr *sfinfo[MPTCP_SUBFLOW_ATTR_MAX + 1] = { 0 };

	parse_rtattr_nested(sfinfo, MPTCP_SUBFLOW_ATTR_MAX,
	ulpinfo[INET_ULP_INFO_MPTCP]);
	print_subflow_info(sfinfo);
	} else {
	printf("It's a normal TCP!\n");
	}
	}
	}

	static void recv_nlmsg(int fd, __u32 proto)
	{
	char rcv_buff[8192];
	struct nlmsghdr nlh = (struct nlmsghdr )rcv_buff;
	struct sockaddr_nl rcv_nladdr = {
	.nl_family = AF_NETLINK
	};
	struct iovec rcv_iov = {
	.iov_base = rcv_buff,
	.iov_len = sizeof(rcv_buff)
	};
	struct msghdr rcv_msg = {
	.msg_name = &rcv_nladdr,
	.msg_namelen = sizeof(rcv_nladdr),
	.msg_iov = &rcv_iov,
	.msg_iovlen = 1
	};
	int len;

	len = recvmsg(fd, &rcv_msg, 0);

	while (NLMSG_OK(nlh, len)) {
	if (nlh->nlmsg_type == NLMSG_DONE) {
	printf("NLMSG_DONE\n");
	break;
	} else if (nlh->nlmsg_type == NLMSG_ERROR) {
	struct nlmsgerr *err;

	err = (struct nlmsgerr *)NLMSG_DATA(nlh);
	printf("Error %d:%s\n",
	-(err->error), strerror(-(err->error)));
	break;
	}
	parse_nlmsg(nlh, proto);
	nlh = NLMSG_NEXT(nlh, len);
	}
	}

	static void get_mptcpinfo(__u32 token)
	{
	struct inet_diag_req_v2 r = {
	.sdiag_family = AF_INET,
	/* Real proto is set via INET_DIAG_REQ_PROTOCOL */
	.sdiag_protocol = IPPROTO_TCP,
	.idiag_ext = 1 << (INET_DIAG_INFO - 1),
	.id.idiag_cookie[0] = token,
	};
	__u32 proto = IPPROTO_MPTCP;
	int fd;

	fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_SOCK_DIAG);
	if (fd < 0)
	die_perror("Netlink socket");

	send_query(fd, &r, proto);
	recv_nlmsg(fd, proto);

	close(fd);
	}

	static void get_subflow_info(char *subflow_addrs)
	{
	struct inet_diag_req_v2 r = {
	.sdiag_family = AF_INET,
	.sdiag_protocol = IPPROTO_TCP,
	.idiag_ext = 1 << (INET_DIAG_INFO - 1),
	.id.idiag_cookie[0] = INET_DIAG_NOCOOKIE,
	.id.idiag_cookie[1] = INET_DIAG_NOCOOKIE,
	};
	char saddr[64], daddr[64];
	int sport, dport;
	int ret;
	int fd;

	ret = sscanf(subflow_addrs, "%[^:]:%d %[^:]:%d", saddr, &sport, daddr, &dport);
	if (ret != 4)
	die_perror("IP PORT Pairs has style problems!");

	printf("%s:%d -> %s:%d\n", saddr, sport, daddr, dport);

	fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_SOCK_DIAG);
	if (fd < 0)
	die_perror("Netlink socket");

	r.id.idiag_sport = htons(sport);
	r.id.idiag_dport = htons(dport);

	inet_pton(AF_INET, saddr, &r.id.idiag_src);
	inet_pton(AF_INET, daddr, &r.id.idiag_dst);
	send_query(fd, &r, IPPROTO_TCP);
	recv_nlmsg(fd, IPPROTO_TCP);
	}

	static void parse_opts(int argc, char *argv, struct params p)
	{
	int c;

	if (argc < 2)
	die_usage(1);

	while ((c = getopt(argc, argv, "ht:s:")) != -1) {
	switch (c) {
	case 'h':
	die_usage(0);
	break;
	case 't':
	sscanf(optarg, "%x", &p->target_token);
	break;
	case 's':
	strncpy(p->subflow_addrs, optarg,
	sizeof(p->subflow_addrs) - 1);
	break;
	default:
	die_usage(1);
	break;
	}
	}
	}

	int main(int argc, char *argv[])
	{
	struct params p = { 0 };

	parse_opts(argc, argv, &p);

	if (p.target_token)
	get_mptcpinfo(p.target_token);

	if (p.subflow_addrs[0] != '\0')
	get_subflow_info(p.subflow_addrs);

	return 0;
	}