selftests: mptcp: refactor NLMSG handling with 'proto'

This patch introduces the '__u32 proto' variable to the 'send_query' and
'recv_nlmsg' functions for further extending function.

In the 'send_query' function, the inclusion of this variable makes the
structure clearer and more readable.

In the 'recv_nlmsg' function, the '__u32 proto' variable ensures that
the 'diag_info' field remains unmodified when processing IPPROTO_TCP data,
thereby preventing unintended transformation into 'mptcp_info' format.

While at it, increment iovlen directly when an item is added to simplify
this portion of the code and improve its readaility.

Co-developed-by: Geliang Tang <geliang@kernel.org>
Signed-off-by: Geliang Tang <geliang@kernel.org>
Signed-off-by: Gang Yan <yangang@kylinos.cn>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20250502-net-next-mptcp-sft-inc-cover-v1-5-68eec95898fb@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/tools/testing/selftests/net/mptcp/mptcp_diag.c b/tools/testing/selftests/net/mptcp/mptcp_diag.c
index 76135aba71ad24c25c7babb6875e8a6dd7636b21..cc0326548e4ec44060da83f1f77e498bcedc82a9 100644 (file)
--- a/tools/testing/selftests/net/mptcp/mptcp_diag.c
+++ b/tools/testing/selftests/net/mptcp/mptcp_diag.c
@@ -62,7 +62,7 @@ static void die_usage(int r)
        exit(r);
 }
 
-static void send_query(int fd, struct inet_diag_req_v2 *r)
+static void send_query(int fd, struct inet_diag_req_v2 *r, __u32 proto)
 {
        struct sockaddr_nl nladdr = {
                .nl_family = AF_NETLINK
@@ -80,21 +80,22 @@ static void send_query(int fd, struct inet_diag_req_v2 *r)
        };
        struct rtattr rta_proto;
        struct iovec iov[6];
-       int iovlen = 1;
-       __u32 proto;
+       int iovlen = 0;
 
-       proto = IPPROTO_MPTCP;
-       rta_proto.rta_type = INET_DIAG_REQ_PROTOCOL;
-       rta_proto.rta_len = RTA_LENGTH(sizeof(proto));
-
-       iov[0] = (struct iovec) {
+       iov[iovlen++] = (struct iovec) {
                .iov_base = &req,
                .iov_len = sizeof(req)
        };
-       iov[iovlen] = (struct iovec){ &rta_proto, sizeof(rta_proto)};
-       iov[iovlen + 1] = (struct iovec){ &proto, sizeof(proto)};
-       req.nlh.nlmsg_len += RTA_LENGTH(sizeof(proto));
-       iovlen += 2;
+
+       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),
@@ -158,7 +159,7 @@ static void print_info_msg(struct mptcp_info *info)
        printf("bytes_acked:      %llu\n", info->mptcpi_bytes_acked);
 }
 
-static void parse_nlmsg(struct nlmsghdr *nlh)
+static void parse_nlmsg(struct nlmsghdr *nlh, __u32 proto)
 {
        struct inet_diag_msg *r = NLMSG_DATA(nlh);
        struct rtattr *tb[INET_DIAG_MAX + 1];
@@ -167,7 +168,7 @@ static void parse_nlmsg(struct nlmsghdr *nlh)
                           nlh->nlmsg_len - NLMSG_LENGTH(sizeof(*r)),
                           NLA_F_NESTED);
 
-       if (tb[INET_DIAG_INFO]) {
+       if (proto == IPPROTO_MPTCP && tb[INET_DIAG_INFO]) {
                int len = RTA_PAYLOAD(tb[INET_DIAG_INFO]);
                struct mptcp_info *info;
 
@@ -183,7 +184,7 @@ static void parse_nlmsg(struct nlmsghdr *nlh)
        }
 }
 
-static void recv_nlmsg(int fd)
+static void recv_nlmsg(int fd, __u32 proto)
 {
        char rcv_buff[8192];
        struct nlmsghdr *nlh = (struct nlmsghdr *)rcv_buff;
@@ -216,7 +217,7 @@ static void recv_nlmsg(int fd)
                               -(err->error), strerror(-(err->error)));
                        break;
                }
-               parse_nlmsg(nlh);
+               parse_nlmsg(nlh, proto);
                nlh = NLMSG_NEXT(nlh, len);
        }
 }
@@ -230,14 +231,15 @@ static void get_mptcpinfo(__u32 token)
                .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);
-       recv_nlmsg(fd);
+       send_query(fd, &r, proto);
+       recv_nlmsg(fd, proto);
 
        close(fd);
 }