ipneigh: neigh get support

This patch adds support to lookup a neigh entry
using recently added support in the kernel using RTM_GETNEIGH

example:
$ip neigh get 10.0.2.4 dev test-dummy0
10.0.2.4 dev test-dummy0 lladdr de:ad:be:ef:13:37 PERMANENT

Signed-off-by: Roopa Prabhu <roopa@cumulusnetworks.com>
Tested-by: Ivan Vecera <ivecera@redhat.com>
Signed-off-by: David Ahern <dsahern@gmail.com>

diff --git a/ip/ipneigh.c b/ip/ipneigh.c
index a3869c841f97cdbf370961e82da7b088093dda93..678b40341539fd81bdc7368e765d01be8668fea3 100644 (file)
--- a/ip/ipneigh.c
+++ b/ip/ipneigh.c
@@ -55,6 +55,7 @@ static void usage(void)
                "\n"
                "       ip neigh { show | flush } [ proxy ] [ to PREFIX ] [ dev DEV ] [ nud STATE ]\n"
                "                                 [ vrf NAME ]\n"
+               "       ip neigh get { ADDR | proxy ADDR } dev DEV\n"
                "\n"
                "STATE := { permanent | noarp | stale | reachable | none |\n"
                "           incomplete | delay | probe | failed }\n");
@@ -599,6 +600,82 @@ static int do_show_or_flush(int argc, char **argv, int flush)
        return 0;
 }
 
+static int ipneigh_get(int argc, char **argv)
+{
+       struct {
+               struct nlmsghdr n;
+               struct ndmsg            ndm;
+               char                    buf[1024];
+       } req = {
+               .n.nlmsg_len = NLMSG_LENGTH(sizeof(struct ndmsg)),
+               .n.nlmsg_flags = NLM_F_REQUEST,
+               .n.nlmsg_type = RTM_GETNEIGH,
+               .ndm.ndm_family = preferred_family,
+       };
+       struct nlmsghdr *answer;
+       char  *d = NULL;
+       int dst_ok = 0;
+       int dev_ok = 0;
+       inet_prefix dst;
+
+       while (argc > 0) {
+               if (strcmp(*argv, "dev") == 0) {
+                       NEXT_ARG();
+                       d = *argv;
+                       dev_ok = 1;
+               } else if (matches(*argv, "proxy") == 0) {
+                       NEXT_ARG();
+                       if (matches(*argv, "help") == 0)
+                               usage();
+                       if (dst_ok)
+                               duparg("address", *argv);
+                       get_addr(&dst, *argv, preferred_family);
+                       dst_ok = 1;
+                       dev_ok = 1;
+                       req.ndm.ndm_flags |= NTF_PROXY;
+               } else {
+                       if (strcmp(*argv, "to") == 0)
+                               NEXT_ARG();
+
+                       if (matches(*argv, "help") == 0)
+                               usage();
+                       if (dst_ok)
+                               duparg2("to", *argv);
+                       get_addr(&dst, *argv, preferred_family);
+                       dst_ok = 1;
+               }
+               argc--; argv++;
+       }
+
+       if (!dev_ok || !dst_ok || dst.family == AF_UNSPEC) {
+               fprintf(stderr, "Device and address are required arguments.\n");
+               return -1;
+       }
+
+       req.ndm.ndm_family = dst.family;
+       if (addattr_l(&req.n, sizeof(req), NDA_DST, &dst.data, dst.bytelen) < 0)
+               return -1;
+
+       if (d) {
+               req.ndm.ndm_ifindex = ll_name_to_index(d);
+               if (!req.ndm.ndm_ifindex) {
+                       fprintf(stderr, "Cannot find device \"%s\"\n", d);
+                       return -1;
+               }
+       }
+
+       if (rtnl_talk(&rth, &req.n, &answer) < 0)
+               return -2;
+
+       ipneigh_reset_filter(0);
+       if (print_neigh(answer, stdout) < 0) {
+               fprintf(stderr, "An error :-)\n");
+               return -1;
+       }
+
+       return 0;
+}
+
 int do_ipneigh(int argc, char **argv)
 {
        if (argc > 0) {
@@ -611,10 +688,8 @@ int do_ipneigh(int argc, char **argv)
                        return ipneigh_modify(RTM_NEWNEIGH, NLM_F_CREATE|NLM_F_REPLACE, argc-1, argv+1);
                if (matches(*argv, "delete") == 0)
                        return ipneigh_modify(RTM_DELNEIGH, 0, argc-1, argv+1);
-               if (matches(*argv, "get") == 0) {
-                       fprintf(stderr, "Sorry, \"neigh get\" is not implemented :-(\n");
-                       return -1;
-               }
+               if (matches(*argv, "get") == 0)
+                       return ipneigh_get(argc-1, argv+1);
                if (matches(*argv, "show") == 0 ||
                    matches(*argv, "lst") == 0 ||
                    matches(*argv, "list") == 0)

diff --git a/man/man8/ip-neighbour.8 b/man/man8/ip-neighbour.8
index 4a672bb542f9e47e74d617e812006d2919248632..bc77b4391683109763eb682349adaf1a38cbaf79 100644 (file)
--- a/man/man8/ip-neighbour.8
+++ b/man/man8/ip-neighbour.8
@@ -37,6 +37,12 @@ ip-neighbour \- neighbour/arp tables management.
 .B  vrf
 .IR NAME " ] "
 
+.ti -8
+.B ip neigh get
+.IR ADDR
+.B  dev
+.IR DEV
+
 .ti -8
 .IR STATE " := {"
 .BR permanent " | " noarp " | " stale " | " reachable " | " none " |"
@@ -231,6 +237,23 @@ twice,
 also dumps all the deleted neighbours.
 .RE
 
+.TP
+ip neigh get
+lookup a neighbour entry to a destination given a device
+.RS
+
+.TP
+.BI proxy
+indicates whether we should lookup a proxy neigbour entry
+
+.TP
+.BI to " ADDRESS " (default)
+the prefix selecting the neighbour to query.
+
+.TP
+.BI dev " NAME"
+get neighbour entry attached to this device.
+
 .SH EXAMPLES
 .PP
 ip neighbour
@@ -242,6 +265,12 @@ ip neigh flush dev eth0
 .RS
 Removes entries in the neighbour table on device eth0.
 .RE
+.PP
+ip neigh get 10.0.1.10 dev eth0
+.RS
+Performs a neighbour lookup in the kernel and returns
+a neighbour entry.
+.RE
 
 .SH SEE ALSO
 .br