xdp: Sample xdp program implementing ip forward
authorChristina Jacob <Christina.Jacob@cavium.com>
Sun, 5 Nov 2017 03:22:30 +0000 (08:52 +0530)
committerDavid S. Miller <davem@davemloft.net>
Wed, 8 Nov 2017 01:39:41 +0000 (10:39 +0900)
Implements port to port forwarding with route table and arp table
lookup for ipv4 packets using bpf_redirect helper function and
lpm_trie  map.

Signed-off-by: Christina Jacob <Christina.Jacob@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
samples/bpf/Makefile
samples/bpf/xdp_router_ipv4_kern.c [new file with mode: 0644]
samples/bpf/xdp_router_ipv4_user.c [new file with mode: 0644]

index 5994075b080d83b336df17c4b0156f668773068f..3b4945c1eab06aec48c326f6b1d822cb158461ff 100644 (file)
@@ -29,6 +29,7 @@ hostprogs-y += test_cgrp2_sock
 hostprogs-y += test_cgrp2_sock2
 hostprogs-y += xdp1
 hostprogs-y += xdp2
+hostprogs-y += xdp_router_ipv4
 hostprogs-y += test_current_task_under_cgroup
 hostprogs-y += trace_event
 hostprogs-y += sampleip
@@ -76,6 +77,7 @@ test_cgrp2_sock2-objs := bpf_load.o $(LIBBPF) test_cgrp2_sock2.o
 xdp1-objs := bpf_load.o $(LIBBPF) xdp1_user.o
 # reuse xdp1 source intentionally
 xdp2-objs := bpf_load.o $(LIBBPF) xdp1_user.o
+xdp_router_ipv4-objs := bpf_load.o $(LIBBPF) xdp_router_ipv4_user.o
 test_current_task_under_cgroup-objs := bpf_load.o $(LIBBPF) $(CGROUP_HELPERS) \
                                       test_current_task_under_cgroup_user.o
 trace_event-objs := bpf_load.o $(LIBBPF) trace_event_user.o
@@ -118,6 +120,7 @@ always += parse_varlen.o parse_simple.o parse_ldabs.o
 always += test_cgrp2_tc_kern.o
 always += xdp1_kern.o
 always += xdp2_kern.o
+always += xdp_router_ipv4_kern.o
 always += test_current_task_under_cgroup_kern.o
 always += trace_event_kern.o
 always += sampleip_kern.o
@@ -166,6 +169,7 @@ HOSTLOADLIBES_map_perf_test += -lelf -lrt
 HOSTLOADLIBES_test_overhead += -lelf -lrt
 HOSTLOADLIBES_xdp1 += -lelf
 HOSTLOADLIBES_xdp2 += -lelf
+HOSTLOADLIBES_xdp_router_ipv4 += -lelf
 HOSTLOADLIBES_test_current_task_under_cgroup += -lelf
 HOSTLOADLIBES_trace_event += -lelf
 HOSTLOADLIBES_sampleip += -lelf
diff --git a/samples/bpf/xdp_router_ipv4_kern.c b/samples/bpf/xdp_router_ipv4_kern.c
new file mode 100644 (file)
index 0000000..993f56b
--- /dev/null
@@ -0,0 +1,186 @@
+/* Copyright (C) 2017 Cavium, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of version 2 of the GNU General Public License
+ * as published by the Free Software Foundation.
+ */
+#define KBUILD_MODNAME "foo"
+#include <uapi/linux/bpf.h>
+#include <linux/in.h>
+#include <linux/if_ether.h>
+#include <linux/if_packet.h>
+#include <linux/if_vlan.h>
+#include <linux/ip.h>
+#include <linux/ipv6.h>
+#include "bpf_helpers.h"
+#include <linux/slab.h>
+#include <net/ip_fib.h>
+
+struct trie_value {
+       __u8 prefix[4];
+       __be64 value;
+       int ifindex;
+       int metric;
+       __be32 gw;
+};
+
+/* Key for lpm_trie*/
+union key_4 {
+       u32 b32[2];
+       u8 b8[8];
+};
+
+struct arp_entry {
+       __be64 mac;
+       __be32 dst;
+};
+
+struct direct_map {
+       struct arp_entry arp;
+       int ifindex;
+       __be64 mac;
+};
+
+/* Map for trie implementation*/
+struct bpf_map_def SEC("maps") lpm_map = {
+       .type = BPF_MAP_TYPE_LPM_TRIE,
+       .key_size = 8,
+       .value_size = sizeof(struct trie_value),
+       .max_entries = 50,
+       .map_flags = BPF_F_NO_PREALLOC,
+};
+
+/* Map for counter*/
+struct bpf_map_def SEC("maps") rxcnt = {
+       .type = BPF_MAP_TYPE_PERCPU_ARRAY,
+       .key_size = sizeof(u32),
+       .value_size = sizeof(u64),
+       .max_entries = 256,
+};
+
+/* Map for ARP table*/
+struct bpf_map_def SEC("maps") arp_table = {
+       .type = BPF_MAP_TYPE_HASH,
+       .key_size = sizeof(__be32),
+       .value_size = sizeof(__be64),
+       .max_entries = 50,
+};
+
+/* Map to keep the exact match entries in the route table*/
+struct bpf_map_def SEC("maps") exact_match = {
+       .type = BPF_MAP_TYPE_HASH,
+       .key_size = sizeof(__be32),
+       .value_size = sizeof(struct direct_map),
+       .max_entries = 50,
+};
+
+struct bpf_map_def SEC("maps") tx_port = {
+       .type = BPF_MAP_TYPE_DEVMAP,
+       .key_size = sizeof(int),
+       .value_size = sizeof(int),
+       .max_entries = 100,
+};
+
+/* Function to set source and destination mac of the packet */
+static inline void set_src_dst_mac(void *data, void *src, void *dst)
+{
+       unsigned short *source = src;
+       unsigned short *dest  = dst;
+       unsigned short *p = data;
+
+       __builtin_memcpy(p, dest, 6);
+       __builtin_memcpy(p + 3, source, 6);
+}
+
+/* Parse IPV4 packet to get SRC, DST IP and protocol */
+static inline int parse_ipv4(void *data, u64 nh_off, void *data_end,
+                            __be32 *src, __be32 *dest)
+{
+       struct iphdr *iph = data + nh_off;
+
+       if (iph + 1 > data_end)
+               return 0;
+       *src = iph->saddr;
+       *dest = iph->daddr;
+       return iph->protocol;
+}
+
+SEC("xdp_router_ipv4")
+int xdp_router_ipv4_prog(struct xdp_md *ctx)
+{
+       void *data_end = (void *)(long)ctx->data_end;
+       __be64 *dest_mac = NULL, *src_mac = NULL;
+       void *data = (void *)(long)ctx->data;
+       struct trie_value *prefix_value;
+       int rc = XDP_DROP, forward_to;
+       struct ethhdr *eth = data;
+       union key_4 key4;
+       long *value;
+       u16 h_proto;
+       u32 ipproto;
+       u64 nh_off;
+
+       nh_off = sizeof(*eth);
+       if (data + nh_off > data_end)
+               return rc;
+
+       h_proto = eth->h_proto;
+
+       if (h_proto == htons(ETH_P_8021Q) || h_proto == htons(ETH_P_8021AD)) {
+               struct vlan_hdr *vhdr;
+
+               vhdr = data + nh_off;
+               nh_off += sizeof(struct vlan_hdr);
+               if (data + nh_off > data_end)
+                       return rc;
+               h_proto = vhdr->h_vlan_encapsulated_proto;
+       }
+       if (h_proto == htons(ETH_P_ARP)) {
+               return XDP_PASS;
+       } else if (h_proto == htons(ETH_P_IP)) {
+               struct direct_map *direct_entry;
+               __be32 src_ip = 0, dest_ip = 0;
+
+               ipproto = parse_ipv4(data, nh_off, data_end, &src_ip, &dest_ip);
+               direct_entry = bpf_map_lookup_elem(&exact_match, &dest_ip);
+               /* Check for exact match, this would give a faster lookup*/
+               if (direct_entry && direct_entry->mac && direct_entry->arp.mac) {
+                       src_mac = &direct_entry->mac;
+                       dest_mac = &direct_entry->arp.mac;
+                       forward_to = direct_entry->ifindex;
+               } else {
+                       /* Look up in the trie for lpm*/
+                       key4.b32[0] = 32;
+                       key4.b8[4] = dest_ip & 0xff;
+                       key4.b8[5] = (dest_ip >> 8) & 0xff;
+                       key4.b8[6] = (dest_ip >> 16) & 0xff;
+                       key4.b8[7] = (dest_ip >> 24) & 0xff;
+                       prefix_value = bpf_map_lookup_elem(&lpm_map, &key4);
+                       if (!prefix_value)
+                               return XDP_DROP;
+                       src_mac = &prefix_value->value;
+                       if (!src_mac)
+                               return XDP_DROP;
+                       dest_mac = bpf_map_lookup_elem(&arp_table, &dest_ip);
+                       if (!dest_mac) {
+                               if (!prefix_value->gw)
+                                       return XDP_DROP;
+                               dest_ip = prefix_value->gw;
+                               dest_mac = bpf_map_lookup_elem(&arp_table, &dest_ip);
+                       }
+                       forward_to = prefix_value->ifindex;
+               }
+       } else {
+               ipproto = 0;
+       }
+       if (src_mac && dest_mac) {
+               set_src_dst_mac(data, src_mac, dest_mac);
+               value = bpf_map_lookup_elem(&rxcnt, &ipproto);
+               if (value)
+                       *value += 1;
+               return  bpf_redirect_map(&tx_port, forward_to, 0);
+       }
+       return rc;
+}
+
+char _license[] SEC("license") = "GPL";
diff --git a/samples/bpf/xdp_router_ipv4_user.c b/samples/bpf/xdp_router_ipv4_user.c
new file mode 100644 (file)
index 0000000..2c1fe3f
--- /dev/null
@@ -0,0 +1,659 @@
+/* Copyright (C) 2017 Cavium, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of version 2 of the GNU General Public License
+ * as published by the Free Software Foundation.
+ */
+#include <linux/bpf.h>
+#include <linux/netlink.h>
+#include <linux/rtnetlink.h>
+#include <assert.h>
+#include <errno.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <unistd.h>
+#include "bpf_load.h"
+#include "libbpf.h"
+#include <arpa/inet.h>
+#include <fcntl.h>
+#include <poll.h>
+#include <net/if.h>
+#include <netdb.h>
+#include <sys/ioctl.h>
+#include <sys/syscall.h>
+#include "bpf_util.h"
+
+int sock, sock_arp, flags = 0;
+static int total_ifindex;
+int *ifindex_list;
+char buf[8192];
+
+static int get_route_table(int rtm_family);
+static void int_exit(int sig)
+{
+       int i = 0;
+
+       for (i = 0; i < total_ifindex; i++)
+               set_link_xdp_fd(ifindex_list[i], -1, flags);
+       exit(0);
+}
+
+static void close_and_exit(int sig)
+{
+       int i = 0;
+
+       close(sock);
+       close(sock_arp);
+
+       for (i = 0; i < total_ifindex; i++)
+               set_link_xdp_fd(ifindex_list[i], -1, flags);
+       exit(0);
+}
+
+/* Get the mac address of the interface given interface name */
+static __be64 getmac(char *iface)
+{
+       struct ifreq ifr;
+       __be64 mac = 0;
+       int fd, i;
+
+       fd = socket(AF_INET, SOCK_DGRAM, 0);
+       ifr.ifr_addr.sa_family = AF_INET;
+       strncpy(ifr.ifr_name, iface, IFNAMSIZ - 1);
+       if (ioctl(fd, SIOCGIFHWADDR, &ifr) < 0) {
+               printf("ioctl failed leaving....\n");
+               return -1;
+       }
+       for (i = 0; i < 6 ; i++)
+               *((__u8 *)&mac + i) = (__u8)ifr.ifr_hwaddr.sa_data[i];
+       close(fd);
+       return mac;
+}
+
+static int recv_msg(struct sockaddr_nl sock_addr, int sock)
+{
+       struct nlmsghdr *nh;
+       int len, nll = 0;
+       char *buf_ptr;
+
+       buf_ptr = buf;
+       while (1) {
+               len = recv(sock, buf_ptr, sizeof(buf) - nll, 0);
+               if (len < 0)
+                       return len;
+
+               nh = (struct nlmsghdr *)buf_ptr;
+
+               if (nh->nlmsg_type == NLMSG_DONE)
+                       break;
+               buf_ptr += len;
+               nll += len;
+               if ((sock_addr.nl_groups & RTMGRP_NEIGH) == RTMGRP_NEIGH)
+                       break;
+
+               if ((sock_addr.nl_groups & RTMGRP_IPV4_ROUTE) == RTMGRP_IPV4_ROUTE)
+                       break;
+       }
+       return nll;
+}
+
+/* Function to parse the route entry returned by netlink
+ * Updates the route entry related map entries
+ */
+static void read_route(struct nlmsghdr *nh, int nll)
+{
+       char dsts[24], gws[24], ifs[16], dsts_len[24], metrics[24];
+       struct bpf_lpm_trie_key *prefix_key;
+       struct rtattr *rt_attr;
+       struct rtmsg *rt_msg;
+       int rtm_family;
+       int rtl;
+       int i;
+       struct route_table {
+               int  dst_len, iface, metric;
+               char *iface_name;
+               __be32 dst, gw;
+               __be64 mac;
+       } route;
+       struct arp_table {
+               __be64 mac;
+               __be32 dst;
+       };
+
+       struct direct_map {
+               struct arp_table arp;
+               int ifindex;
+               __be64 mac;
+       } direct_entry;
+
+       if (nh->nlmsg_type == RTM_DELROUTE)
+               printf("DELETING Route entry\n");
+       else if (nh->nlmsg_type == RTM_GETROUTE)
+               printf("READING Route entry\n");
+       else if (nh->nlmsg_type == RTM_NEWROUTE)
+               printf("NEW Route entry\n");
+       else
+               printf("%d\n", nh->nlmsg_type);
+
+       memset(&route, 0, sizeof(route));
+       printf("Destination\t\tGateway\t\tGenmask\t\tMetric\t\tIface\n");
+       for (; NLMSG_OK(nh, nll); nh = NLMSG_NEXT(nh, nll)) {
+               rt_msg = (struct rtmsg *)NLMSG_DATA(nh);
+               rtm_family = rt_msg->rtm_family;
+               if (rtm_family == AF_INET)
+                       if (rt_msg->rtm_table != RT_TABLE_MAIN)
+                               continue;
+               rt_attr = (struct rtattr *)RTM_RTA(rt_msg);
+               rtl = RTM_PAYLOAD(nh);
+
+               for (; RTA_OK(rt_attr, rtl); rt_attr = RTA_NEXT(rt_attr, rtl)) {
+                       switch (rt_attr->rta_type) {
+                       case NDA_DST:
+                               sprintf(dsts, "%u",
+                                       (*((__be32 *)RTA_DATA(rt_attr))));
+                               break;
+                       case RTA_GATEWAY:
+                               sprintf(gws, "%u",
+                                       *((__be32 *)RTA_DATA(rt_attr)));
+                               break;
+                       case RTA_OIF:
+                               sprintf(ifs, "%u",
+                                       *((int *)RTA_DATA(rt_attr)));
+                               break;
+                       case RTA_METRICS:
+                               sprintf(metrics, "%u",
+                                       *((int *)RTA_DATA(rt_attr)));
+                       default:
+                               break;
+                       }
+               }
+               sprintf(dsts_len, "%d", rt_msg->rtm_dst_len);
+               route.dst = atoi(dsts);
+               route.dst_len = atoi(dsts_len);
+               route.gw = atoi(gws);
+               route.iface = atoi(ifs);
+               route.metric = atoi(metrics);
+               route.iface_name = alloca(sizeof(char *) * IFNAMSIZ);
+               route.iface_name = if_indextoname(route.iface, route.iface_name);
+               route.mac = getmac(route.iface_name);
+               if (route.mac == -1) {
+                       int i = 0;
+
+                       for (i = 0; i < total_ifindex; i++)
+                               set_link_xdp_fd(ifindex_list[i], -1, flags);
+                       exit(0);
+               }
+               assert(bpf_map_update_elem(map_fd[4], &route.iface, &route.iface, 0) == 0);
+               if (rtm_family == AF_INET) {
+                       struct trie_value {
+                               __u8 prefix[4];
+                               __be64 value;
+                               int ifindex;
+                               int metric;
+                               __be32 gw;
+                       } *prefix_value;
+
+                       prefix_key = alloca(sizeof(*prefix_key) + 3);
+                       prefix_value = alloca(sizeof(*prefix_value));
+
+                       prefix_key->prefixlen = 32;
+                       prefix_key->prefixlen = route.dst_len;
+                       direct_entry.mac = route.mac & 0xffffffffffff;
+                       direct_entry.ifindex = route.iface;
+                       direct_entry.arp.mac = 0;
+                       direct_entry.arp.dst = 0;
+                       if (route.dst_len == 32) {
+                               if (nh->nlmsg_type == RTM_DELROUTE)
+                                       assert(bpf_map_delete_elem(map_fd[3], &route.dst) == 0);
+                               else
+                                       if (bpf_map_lookup_elem(map_fd[2], &route.dst, &direct_entry.arp.mac) == 0)
+                                               direct_entry.arp.dst = route.dst;
+                                       assert(bpf_map_update_elem(map_fd[3], &route.dst, &direct_entry, 0) == 0);
+                       }
+                       for (i = 0; i < 4; i++)
+                               prefix_key->data[i] = (route.dst >> i * 8) & 0xff;
+
+                       printf("%3d.%d.%d.%d\t\t%3x\t\t%d\t\t%d\t\t%s\n",
+                              (int)prefix_key->data[0],
+                              (int)prefix_key->data[1],
+                              (int)prefix_key->data[2],
+                              (int)prefix_key->data[3],
+                              route.gw, route.dst_len,
+                              route.metric,
+                              route.iface_name);
+                       if (bpf_map_lookup_elem(map_fd[0], prefix_key,
+                                               prefix_value) < 0) {
+                               for (i = 0; i < 4; i++)
+                                       prefix_value->prefix[i] = prefix_key->data[i];
+                               prefix_value->value = route.mac & 0xffffffffffff;
+                               prefix_value->ifindex = route.iface;
+                               prefix_value->gw = route.gw;
+                               prefix_value->metric = route.metric;
+
+                               assert(bpf_map_update_elem(map_fd[0],
+                                                          prefix_key,
+                                                          prefix_value, 0
+                                                          ) == 0);
+                       } else {
+                               if (nh->nlmsg_type == RTM_DELROUTE) {
+                                       printf("deleting entry\n");
+                                       printf("prefix key=%d.%d.%d.%d/%d",
+                                              prefix_key->data[0],
+                                              prefix_key->data[1],
+                                              prefix_key->data[2],
+                                              prefix_key->data[3],
+                                              prefix_key->prefixlen);
+                                       assert(bpf_map_delete_elem(map_fd[0],
+                                                                  prefix_key
+                                                                  ) == 0);
+                                       /* Rereading the route table to check if
+                                        * there is an entry with the same
+                                        * prefix but a different metric as the
+                                        * deleted enty.
+                                        */
+                                       get_route_table(AF_INET);
+                               } else if (prefix_key->data[0] ==
+                                          prefix_value->prefix[0] &&
+                                          prefix_key->data[1] ==
+                                          prefix_value->prefix[1] &&
+                                          prefix_key->data[2] ==
+                                          prefix_value->prefix[2] &&
+                                          prefix_key->data[3] ==
+                                          prefix_value->prefix[3] &&
+                                          route.metric >= prefix_value->metric) {
+                                       continue;
+                               } else {
+                                       for (i = 0; i < 4; i++)
+                                               prefix_value->prefix[i] =
+                                                       prefix_key->data[i];
+                                       prefix_value->value =
+                                               route.mac & 0xffffffffffff;
+                                       prefix_value->ifindex = route.iface;
+                                       prefix_value->gw = route.gw;
+                                       prefix_value->metric = route.metric;
+                                       assert(bpf_map_update_elem(
+                                                                  map_fd[0],
+                                                                  prefix_key,
+                                                                  prefix_value,
+                                                                  0) == 0);
+                               }
+                       }
+               }
+               memset(&route, 0, sizeof(route));
+               memset(dsts, 0, sizeof(dsts));
+               memset(dsts_len, 0, sizeof(dsts_len));
+               memset(gws, 0, sizeof(gws));
+               memset(ifs, 0, sizeof(ifs));
+               memset(&route, 0, sizeof(route));
+       }
+}
+
+/* Function to read the existing route table  when the process is launched*/
+static int get_route_table(int rtm_family)
+{
+       struct sockaddr_nl sa;
+       struct nlmsghdr *nh;
+       int sock, seq = 0;
+       struct msghdr msg;
+       struct iovec iov;
+       int ret = 0;
+       int nll;
+
+       struct {
+               struct nlmsghdr nl;
+               struct rtmsg rt;
+               char buf[8192];
+       } req;
+
+       sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
+       if (sock < 0) {
+               printf("open netlink socket: %s\n", strerror(errno));
+               return -1;
+       }
+       memset(&sa, 0, sizeof(sa));
+       sa.nl_family = AF_NETLINK;
+       if (bind(sock, (struct sockaddr *)&sa, sizeof(sa)) < 0) {
+               printf("bind to netlink: %s\n", strerror(errno));
+               ret = -1;
+               goto cleanup;
+       }
+       memset(&req, 0, sizeof(req));
+       req.nl.nlmsg_len = NLMSG_LENGTH(sizeof(struct rtmsg));
+       req.nl.nlmsg_flags = NLM_F_REQUEST | NLM_F_DUMP;
+       req.nl.nlmsg_type = RTM_GETROUTE;
+
+       req.rt.rtm_family = rtm_family;
+       req.rt.rtm_table = RT_TABLE_MAIN;
+       req.nl.nlmsg_pid = 0;
+       req.nl.nlmsg_seq = ++seq;
+       memset(&msg, 0, sizeof(msg));
+       iov.iov_base = (void *)&req.nl;
+       iov.iov_len = req.nl.nlmsg_len;
+       msg.msg_iov = &iov;
+       msg.msg_iovlen = 1;
+       ret = sendmsg(sock, &msg, 0);
+       if (ret < 0) {
+               printf("send to netlink: %s\n", strerror(errno));
+               ret = -1;
+               goto cleanup;
+       }
+       memset(buf, 0, sizeof(buf));
+       nll = recv_msg(sa, sock);
+       if (nll < 0) {
+               printf("recv from netlink: %s\n", strerror(nll));
+               ret = -1;
+               goto cleanup;
+       }
+       nh = (struct nlmsghdr *)buf;
+       read_route(nh, nll);
+cleanup:
+       close(sock);
+       return ret;
+}
+
+/* Function to parse the arp entry returned by netlink
+ * Updates the arp entry related map entries
+ */
+static void read_arp(struct nlmsghdr *nh, int nll)
+{
+       struct rtattr *rt_attr;
+       char dsts[24], mac[24];
+       struct ndmsg *rt_msg;
+       int rtl, ndm_family;
+
+       struct arp_table {
+               __be64 mac;
+               __be32 dst;
+       } arp_entry;
+       struct direct_map {
+               struct arp_table arp;
+               int ifindex;
+               __be64 mac;
+       } direct_entry;
+
+       if (nh->nlmsg_type == RTM_GETNEIGH)
+               printf("READING arp entry\n");
+       printf("Address\tHwAddress\n");
+       for (; NLMSG_OK(nh, nll); nh = NLMSG_NEXT(nh, nll)) {
+               rt_msg = (struct ndmsg *)NLMSG_DATA(nh);
+               rt_attr = (struct rtattr *)RTM_RTA(rt_msg);
+               ndm_family = rt_msg->ndm_family;
+               rtl = RTM_PAYLOAD(nh);
+               for (; RTA_OK(rt_attr, rtl); rt_attr = RTA_NEXT(rt_attr, rtl)) {
+                       switch (rt_attr->rta_type) {
+                       case NDA_DST:
+                               sprintf(dsts, "%u",
+                                       *((__be32 *)RTA_DATA(rt_attr)));
+                               break;
+                       case NDA_LLADDR:
+                               sprintf(mac, "%lld",
+                                       *((__be64 *)RTA_DATA(rt_attr)));
+                               break;
+                       default:
+                               break;
+                       }
+               }
+               arp_entry.dst = atoi(dsts);
+               arp_entry.mac = atol(mac);
+               printf("%x\t\t%llx\n", arp_entry.dst, arp_entry.mac);
+               if (ndm_family == AF_INET) {
+                       if (bpf_map_lookup_elem(map_fd[3], &arp_entry.dst,
+                                               &direct_entry) == 0) {
+                               if (nh->nlmsg_type == RTM_DELNEIGH) {
+                                       direct_entry.arp.dst = 0;
+                                       direct_entry.arp.mac = 0;
+                               } else if (nh->nlmsg_type == RTM_NEWNEIGH) {
+                                       direct_entry.arp.dst = arp_entry.dst;
+                                       direct_entry.arp.mac = arp_entry.mac;
+                               }
+                               assert(bpf_map_update_elem(map_fd[3],
+                                                          &arp_entry.dst,
+                                                          &direct_entry, 0
+                                                          ) == 0);
+                               memset(&direct_entry, 0, sizeof(direct_entry));
+                       }
+                       if (nh->nlmsg_type == RTM_DELNEIGH) {
+                               assert(bpf_map_delete_elem(map_fd[2], &arp_entry.dst) == 0);
+                       } else if (nh->nlmsg_type == RTM_NEWNEIGH) {
+                               assert(bpf_map_update_elem(map_fd[2],
+                                                          &arp_entry.dst,
+                                                          &arp_entry.mac, 0
+                                                          ) == 0);
+                       }
+               }
+               memset(&arp_entry, 0, sizeof(arp_entry));
+               memset(dsts, 0, sizeof(dsts));
+       }
+}
+
+/* Function to read the existing arp table  when the process is launched*/
+static int get_arp_table(int rtm_family)
+{
+       struct sockaddr_nl sa;
+       struct nlmsghdr *nh;
+       int sock, seq = 0;
+       struct msghdr msg;
+       struct iovec iov;
+       int ret = 0;
+       int nll;
+       struct {
+               struct nlmsghdr nl;
+               struct ndmsg rt;
+               char buf[8192];
+       } req;
+
+       sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
+       if (sock < 0) {
+               printf("open netlink socket: %s\n", strerror(errno));
+               return -1;
+       }
+       memset(&sa, 0, sizeof(sa));
+       sa.nl_family = AF_NETLINK;
+       if (bind(sock, (struct sockaddr *)&sa, sizeof(sa)) < 0) {
+               printf("bind to netlink: %s\n", strerror(errno));
+               ret = -1;
+               goto cleanup;
+       }
+       memset(&req, 0, sizeof(req));
+       req.nl.nlmsg_len = NLMSG_LENGTH(sizeof(struct rtmsg));
+       req.nl.nlmsg_flags = NLM_F_REQUEST | NLM_F_DUMP;
+       req.nl.nlmsg_type = RTM_GETNEIGH;
+       req.rt.ndm_state = NUD_REACHABLE;
+       req.rt.ndm_family = rtm_family;
+       req.nl.nlmsg_pid = 0;
+       req.nl.nlmsg_seq = ++seq;
+       memset(&msg, 0, sizeof(msg));
+       iov.iov_base = (void *)&req.nl;
+       iov.iov_len = req.nl.nlmsg_len;
+       msg.msg_iov = &iov;
+       msg.msg_iovlen = 1;
+       ret = sendmsg(sock, &msg, 0);
+       if (ret < 0) {
+               printf("send to netlink: %s\n", strerror(errno));
+               ret = -1;
+               goto cleanup;
+       }
+       memset(buf, 0, sizeof(buf));
+       nll = recv_msg(sa, sock);
+       if (nll < 0) {
+               printf("recv from netlink: %s\n", strerror(nll));
+               ret = -1;
+               goto cleanup;
+       }
+       nh = (struct nlmsghdr *)buf;
+       read_arp(nh, nll);
+cleanup:
+       close(sock);
+       return ret;
+}
+
+/* Function to keep track and update changes in route and arp table
+ * Give regular statistics of packets forwarded
+ */
+static int monitor_route(void)
+{
+       unsigned int nr_cpus = bpf_num_possible_cpus();
+       const unsigned int nr_keys = 256;
+       struct pollfd fds_route, fds_arp;
+       __u64 prev[nr_keys][nr_cpus];
+       struct sockaddr_nl la, lr;
+       __u64 values[nr_cpus];
+       struct nlmsghdr *nh;
+       int nll, ret = 0;
+       int interval = 5;
+       __u32 key;
+       int i;
+
+       sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
+       if (sock < 0) {
+               printf("open netlink socket: %s\n", strerror(errno));
+               return -1;
+       }
+
+       fcntl(sock, F_SETFL, O_NONBLOCK);
+       memset(&lr, 0, sizeof(lr));
+       lr.nl_family = AF_NETLINK;
+       lr.nl_groups = RTMGRP_IPV6_ROUTE | RTMGRP_IPV4_ROUTE | RTMGRP_NOTIFY;
+       if (bind(sock, (struct sockaddr *)&lr, sizeof(lr)) < 0) {
+               printf("bind to netlink: %s\n", strerror(errno));
+               ret = -1;
+               goto cleanup;
+       }
+       fds_route.fd = sock;
+       fds_route.events = POLL_IN;
+
+       sock_arp = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
+       if (sock_arp < 0) {
+               printf("open netlink socket: %s\n", strerror(errno));
+               return -1;
+       }
+
+       fcntl(sock_arp, F_SETFL, O_NONBLOCK);
+       memset(&la, 0, sizeof(la));
+       la.nl_family = AF_NETLINK;
+       la.nl_groups = RTMGRP_NEIGH | RTMGRP_NOTIFY;
+       if (bind(sock_arp, (struct sockaddr *)&la, sizeof(la)) < 0) {
+               printf("bind to netlink: %s\n", strerror(errno));
+               ret = -1;
+               goto cleanup;
+       }
+       fds_arp.fd = sock_arp;
+       fds_arp.events = POLL_IN;
+
+       memset(prev, 0, sizeof(prev));
+       do {
+               signal(SIGINT, close_and_exit);
+               signal(SIGTERM, close_and_exit);
+
+               sleep(interval);
+               for (key = 0; key < nr_keys; key++) {
+                       __u64 sum = 0;
+
+                       assert(bpf_map_lookup_elem(map_fd[1], &key, values) == 0);
+                       for (i = 0; i < nr_cpus; i++)
+                               sum += (values[i] - prev[key][i]);
+                       if (sum)
+                               printf("proto %u: %10llu pkt/s\n",
+                                      key, sum / interval);
+                       memcpy(prev[key], values, sizeof(values));
+               }
+
+               memset(buf, 0, sizeof(buf));
+               if (poll(&fds_route, 1, 3) == POLL_IN) {
+                       nll = recv_msg(lr, sock);
+                       if (nll < 0) {
+                               printf("recv from netlink: %s\n", strerror(nll));
+                               ret = -1;
+                               goto cleanup;
+                       }
+
+                       nh = (struct nlmsghdr *)buf;
+                       printf("Routing table updated.\n");
+                       read_route(nh, nll);
+               }
+               memset(buf, 0, sizeof(buf));
+               if (poll(&fds_arp, 1, 3) == POLL_IN) {
+                       nll = recv_msg(la, sock_arp);
+                       if (nll < 0) {
+                               printf("recv from netlink: %s\n", strerror(nll));
+                               ret = -1;
+                               goto cleanup;
+                       }
+
+                       nh = (struct nlmsghdr *)buf;
+                       read_arp(nh, nll);
+               }
+
+       } while (1);
+cleanup:
+       close(sock);
+       return ret;
+}
+
+int main(int ac, char **argv)
+{
+       char filename[256];
+       char **ifname_list;
+       int i = 1;
+
+       snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
+       if (ac < 2) {
+               printf("usage: %s [-S] Interface name list\n", argv[0]);
+               return 1;
+       }
+       if (!strcmp(argv[1], "-S")) {
+               flags = XDP_FLAGS_SKB_MODE;
+               total_ifindex = ac - 2;
+               ifname_list = (argv + 2);
+       } else {
+               flags = 0;
+               total_ifindex = ac - 1;
+               ifname_list = (argv + 1);
+       }
+       if (load_bpf_file(filename)) {
+               printf("%s", bpf_log_buf);
+               return 1;
+       }
+       printf("\n**************loading bpf file*********************\n\n\n");
+       if (!prog_fd[0]) {
+               printf("load_bpf_file: %s\n", strerror(errno));
+               return 1;
+       }
+       ifindex_list = (int *)malloc(total_ifindex * sizeof(int *));
+       for (i = 0; i < total_ifindex; i++) {
+               ifindex_list[i] = if_nametoindex(ifname_list[i]);
+               if (!ifindex_list[i]) {
+                       printf("Couldn't translate interface name: %s",
+                              strerror(errno));
+                       return 1;
+               }
+       }
+       for (i = 0; i < total_ifindex; i++) {
+               if (set_link_xdp_fd(ifindex_list[i], prog_fd[0], flags) < 0) {
+                       printf("link set xdp fd failed\n");
+                       int recovery_index = i;
+
+                       for (i = 0; i < recovery_index; i++)
+                               set_link_xdp_fd(ifindex_list[i], -1, flags);
+
+                       return 1;
+               }
+               printf("Attached to %d\n", ifindex_list[i]);
+       }
+       signal(SIGINT, int_exit);
+       signal(SIGTERM, int_exit);
+
+       printf("*******************ROUTE TABLE*************************\n\n\n");
+       get_route_table(AF_INET);
+       printf("*******************ARP TABLE***************************\n\n\n");
+       get_arp_table(AF_INET);
+       if (monitor_route() < 0) {
+               printf("Error in receiving route update");
+               return 1;
+       }
+
+       return 0;
+}