From: Gang Yan <yang...@kylinos.cn>

This patch adds 'get_subflow_info' in 'mptcp_diag', which can check whether
a TCP connection is an MPTCP subflow based on the "INET_ULP_INFO_MPTCP"
with tcp_diag method.

The helper 'print_subflow_info' in 'mptcp_diag' can print the subflow_filed
of an MPTCP subflow for further checking the 'subflow_info' through
inet_diag method.

The example of the whole output should be:

  $ ./mptcp_diag -s "127.0.0.1:10000 127.0.0.1:38984"
  127.0.0.1:10000 -> 127.0.0.1:38984
  It's a mptcp subflow, the subflow info:
   flags:Mec token:0000(id:0)/4278e77e(id:0) seq:9288466187236176036 \
   sfseq:1 ssnoff:2317083055 maplen:215

Co-developed-by: Geliang Tang <geli...@kernel.org>
Signed-off-by: Geliang Tang <geli...@kernel.org>
Signed-off-by: Gang Yan <yang...@kylinos.cn>
Reviewed-by: Matthieu Baerts (NGI0) <matt...@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matt...@kernel.org>
---
 tools/testing/selftests/net/mptcp/mptcp_diag.c | 159 ++++++++++++++++++++++++-
 1 file changed, 157 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/net/mptcp/mptcp_diag.c 
b/tools/testing/selftests/net/mptcp/mptcp_diag.c
index 
cc0326548e4ec44060da83f1f77e498bcedc82a9..e084796e804d28e93d04c30cca937fe21be43388
 100644
--- a/tools/testing/selftests/net/mptcp/mptcp_diag.c
+++ b/tools/testing/selftests/net/mptcp/mptcp_diag.c
@@ -8,6 +8,7 @@
 #include <sys/socket.h>
 #include <netinet/in.h>
 #include <linux/tcp.h>
+#include <arpa/inet.h>
 
 #include <unistd.h>
 #include <stdlib.h>
@@ -19,8 +20,13 @@
 #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 {
@@ -50,6 +56,37 @@ struct mptcp_info {
        __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);
@@ -58,7 +95,9 @@ static void die_perror(const char *msg)
 
 static void die_usage(int r)
 {
-       fprintf(stderr, "Usage: mptcp_diag -t\n");
+       fprintf(stderr, "Usage:\n"
+                       "mptcp_diag -t <token>\n"
+                       "mptcp_diag -s \"<saddr>:<sport> <daddr>:<dport>\"\n");
        exit(r);
 }
 
@@ -159,6 +198,66 @@ static void print_info_msg(struct mptcp_info *info)
        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);
@@ -182,6 +281,22 @@ static void parse_nlmsg(struct nlmsghdr *nlh, __u32 proto)
                }
                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)
@@ -244,6 +359,39 @@ static void get_mptcpinfo(__u32 token)
        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;
@@ -251,7 +399,7 @@ static void parse_opts(int argc, char **argv, struct params 
*p)
        if (argc < 2)
                die_usage(1);
 
-       while ((c = getopt(argc, argv, "ht:")) != -1) {
+       while ((c = getopt(argc, argv, "ht:s:")) != -1) {
                switch (c) {
                case 'h':
                        die_usage(0);
@@ -259,6 +407,10 @@ static void parse_opts(int argc, char **argv, struct 
params *p)
                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;
@@ -275,6 +427,9 @@ int main(int argc, char *argv[])
        if (p.target_token)
                get_mptcpinfo(p.target_token);
 
+       if (p.subflow_addrs[0] != '\0')
+               get_subflow_info(p.subflow_addrs);
+
        return 0;
 }
 

-- 
2.48.1


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