mptcp: monitor: add JSON support

The command 'ip [-t[s]] mptcp monitor' now produces an output with the JSON
format.

The previous text output has been preserved.

The JSON support has been added thanks to the print_*() helpers. Note that
it is also needed to add a signal handler to exit without errors in case of
SIGINT or SIGTERM, and close the JSON. This last step will print the final
']' when stopping 'ip -j mptcp monitor'.

Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: David Ahern <dsahern@kernel.org>

diff --git a/ip/ipmptcp.c b/ip/ipmptcp.c
index 18ec05a885f7768dd14c1f7ab0fb1fbd123b2154..3df89db54b4e00f8fe2d18828621999512622d59 100644 (file)
--- a/ip/ipmptcp.c
+++ b/ip/ipmptcp.c
@@ -2,6 +2,7 @@
 
 #include <arpa/inet.h>
 #include <netinet/in.h>
+#include <signal.h>
 #include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -476,8 +477,9 @@ static void print_addr(const char *key, int af, struct rtattr *value)
        char str[INET6_ADDRSTRLEN];
 
        if (inet_ntop(af, data, str, sizeof(str))) {
-               printf(" %s=", key);
-               color_fprintf(stdout, ifa_family_color(af), "%s", str);
+               print_string(PRINT_FP, NULL, " %s=", key);
+               print_color_string(PRINT_ANY, ifa_family_color(af), key, "%s",
+                                  str);
        }
 }
 
@@ -485,12 +487,13 @@ static void print_iface(int index)
 {
        const char *ifname;
 
-       printf(" ifindex=%d", index);
+       print_int(PRINT_ANY, "ifindex", " ifindex=%d", index);
 
        ifname = index ? ll_index_to_name(index) : NULL;
        if (ifname) {
-               printf(" dev=");
-               color_fprintf(stdout, COLOR_IFNAME, "%s", ifname);
+               print_string(PRINT_FP, NULL, " dev=", NULL);
+               print_color_string(PRINT_ANY, COLOR_IFNAME, "dev", "%s",
+                                  ifname);
        }
 }
 
@@ -509,30 +512,34 @@ static int mptcp_monitor_msg(struct rtnl_ctrl_data *ctrl,
        if (n->nlmsg_type != genl_family)
                return 0;
 
+       open_json_object(NULL);
+
        if (timestamp)
                print_timestamp(stdout);
 
-       if (ghdr->cmd >= ARRAY_SIZE(event_to_str)) {
-               printf("[UNKNOWN %u]\n", ghdr->cmd);
-               goto out;
-       }
+       if (ghdr->cmd >= ARRAY_SIZE(event_to_str) ||
+           event_to_str[ghdr->cmd] == NULL) {
+               char event[40];
 
-       if (event_to_str[ghdr->cmd] == NULL) {
-               printf("[UNKNOWN %u]\n", ghdr->cmd);
+               snprintf(event, sizeof(event), "UNKNOWN %u", ghdr->cmd);
+               print_string(PRINT_ANY, "event", "[%s]", event);
                goto out;
        }
 
-       printf("[%16s]", event_to_str[ghdr->cmd]);
+       print_string(PRINT_ANY, "event", "[%16s]", event_to_str[ghdr->cmd]);
 
        parse_rtattr(tb, MPTCP_ATTR_MAX, (void *) ghdr + GENL_HDRLEN, len);
 
        if (tb[MPTCP_ATTR_TOKEN])
-               printf(" token=%08x", rta_getattr_u32(tb[MPTCP_ATTR_TOKEN]));
+               print_0xhex(PRINT_ANY, "token", " token=%08x",
+                           rta_getattr_u32(tb[MPTCP_ATTR_TOKEN]));
 
        if (tb[MPTCP_ATTR_REM_ID])
-               printf(" remid=%u", rta_getattr_u8(tb[MPTCP_ATTR_REM_ID]));
+               print_uint(PRINT_ANY, "remid", " remid=%u",
+                          rta_getattr_u8(tb[MPTCP_ATTR_REM_ID]));
        if (tb[MPTCP_ATTR_LOC_ID])
-               printf(" locid=%u", rta_getattr_u8(tb[MPTCP_ATTR_LOC_ID]));
+               print_uint(PRINT_ANY, "locid", " locid=%u",
+                          rta_getattr_u8(tb[MPTCP_ATTR_LOC_ID]));
 
        if (tb[MPTCP_ATTR_SADDR4])
                print_addr("saddr4", AF_INET, tb[MPTCP_ATTR_SADDR4]);
@@ -543,49 +550,74 @@ static int mptcp_monitor_msg(struct rtnl_ctrl_data *ctrl,
        if (tb[MPTCP_ATTR_DADDR6])
                print_addr("daddr6", AF_INET6, tb[MPTCP_ATTR_DADDR6]);
        if (tb[MPTCP_ATTR_SPORT])
-               printf(" sport=%u", rta_getattr_be16(tb[MPTCP_ATTR_SPORT]));
+               print_uint(PRINT_ANY, "sport", " sport=%u",
+                          rta_getattr_be16(tb[MPTCP_ATTR_SPORT]));
        if (tb[MPTCP_ATTR_DPORT])
-               printf(" dport=%u", rta_getattr_be16(tb[MPTCP_ATTR_DPORT]));
+               print_uint(PRINT_ANY, "dport", " dport=%u",
+                          rta_getattr_be16(tb[MPTCP_ATTR_DPORT]));
        if (tb[MPTCP_ATTR_BACKUP])
-               printf(" backup=%u", rta_getattr_u8(tb[MPTCP_ATTR_BACKUP]));
+               print_uint(PRINT_ANY, "backup", " backup=%u",
+                          rta_getattr_u8(tb[MPTCP_ATTR_BACKUP]));
        if (tb[MPTCP_ATTR_ERROR])
-               printf(" error=%u", rta_getattr_u8(tb[MPTCP_ATTR_ERROR]));
+               print_uint(PRINT_ANY, "error", " error=%u",
+                          rta_getattr_u8(tb[MPTCP_ATTR_ERROR]));
        if (tb[MPTCP_ATTR_TIMEOUT])
-               printf(" timeout=%u", rta_getattr_u32(tb[MPTCP_ATTR_TIMEOUT]));
+               print_uint(PRINT_ANY, "timeout", " timeout=%u",
+                          rta_getattr_u32(tb[MPTCP_ATTR_TIMEOUT]));
        if (tb[MPTCP_ATTR_IF_IDX])
                print_iface(rta_getattr_s32(tb[MPTCP_ATTR_IF_IDX]));
        if (tb[MPTCP_ATTR_RESET_REASON])
-               printf(" reset_reason=%u", rta_getattr_u32(tb[MPTCP_ATTR_RESET_REASON]));
+               print_uint(PRINT_ANY, "reset_reason", " reset_reason=%u",
+                          rta_getattr_u32(tb[MPTCP_ATTR_RESET_REASON]));
        if (tb[MPTCP_ATTR_RESET_FLAGS])
-               printf(" reset_flags=0x%x", rta_getattr_u32(tb[MPTCP_ATTR_RESET_FLAGS]));
+               print_0xhex(PRINT_ANY, "reset_flags", " reset_flags=%#x",
+                           rta_getattr_u32(tb[MPTCP_ATTR_RESET_FLAGS]));
 
        if (tb[MPTCP_ATTR_FLAGS])
                flags = rta_getattr_u16(tb[MPTCP_ATTR_FLAGS]);
        if ((flags & MPTCP_PM_EV_FLAG_SERVER_SIDE) ||
            (tb[MPTCP_ATTR_SERVER_SIDE] && rta_getattr_u8(tb[MPTCP_ATTR_SERVER_SIDE]))) {
                flags &= ~MPTCP_PM_EV_FLAG_SERVER_SIDE;
-               printf(" server_side");
+               print_string(PRINT_FP, NULL, " server_side", NULL);
+               print_bool(PRINT_JSON, "server_side", NULL, true);
        }
        if (flags & MPTCP_PM_EV_FLAG_DENY_JOIN_ID0) {
                flags &= ~MPTCP_PM_EV_FLAG_DENY_JOIN_ID0;
-               printf(" deny_join_id0");
+               print_string(PRINT_FP, NULL, " deny_join_id0", NULL);
+               print_bool(PRINT_JSON, "deny_join_id0", NULL, true);
        }
        if (flags) /* remaining bits */
-               printf(" flags=0x%x", flags);
+               print_0xhex(PRINT_ANY, "flags", " flags=%#x", flags);
 
-       puts("");
 out:
+       print_nl();
+       close_json_object();
        fflush(stdout);
+
        return 0;
 }
 
+static void sig_exit(int signo)
+{
+       exit(0);
+}
+
 static int mptcp_monitor(void)
 {
+       struct sigaction sa = { .sa_handler = sig_exit,
+                               .sa_flags = SA_RESTART };
+
        if (genl_add_mcast_grp(&genl_rth, genl_family, MPTCP_PM_EV_GRP_NAME) < 0) {
                perror("can't subscribe to mptcp events");
                return 1;
        }
 
+       new_json_obj(json);
+       atexit(delete_json_obj);
+
+       sigaction(SIGINT, &sa, NULL);
+       sigaction(SIGTERM, &sa, NULL);
+
        if (rtnl_listen(&genl_rth, mptcp_monitor_msg, stdout) < 0)
                return 2;