/* Copyright (c) 2016 Facebook
   *
   * 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/if_link.h>

  #include <assert.h>
  #include <errno.h>
  #include <signal.h>
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  #include <sys/resource.h>
  #include <arpa/inet.h>
  #include <netinet/ether.h>
  #include <unistd.h>
  #include <time.h>
  #include "bpf_load.h"
  #include "libbpf.h"
  #include "bpf_util.h"
  #include "xdp_tx_iptunnel_common.h"
  
  #define STATS_INTERVAL_S 2U
  
  static int ifindex = -1;

  static __u32 xdp_flags = 0;

  
  static void int_exit(int sig)
  {
  	if (ifindex > -1)

  		set_link_xdp_fd(ifindex, -1, xdp_flags);

  	exit(0);
  }
  
  /* simple per-protocol drop counter
   */
  static void poll_stats(unsigned int kill_after_s)
  {
  	const unsigned int nr_protos = 256;
  	unsigned int nr_cpus = bpf_num_possible_cpus();
  	time_t started_at = time(NULL);
  	__u64 values[nr_cpus], prev[nr_protos][nr_cpus];
  	__u32 proto;
  	int i;
  
  	memset(prev, 0, sizeof(prev));
  
  	while (!kill_after_s || time(NULL) - started_at <= kill_after_s) {
  		sleep(STATS_INTERVAL_S);
  
  		for (proto = 0; proto < nr_protos; proto++) {
  			__u64 sum = 0;

  			assert(bpf_map_lookup_elem(map_fd[0], &proto, values) == 0);

  			for (i = 0; i < nr_cpus; i++)
  				sum += (values[i] - prev[proto][i]);
  
  			if (sum)
  				printf("proto %u: sum:%10llu pkts, rate:%10llu pkts/s
  ",
  				       proto, sum, sum / STATS_INTERVAL_S);
  			memcpy(prev[proto], values, sizeof(values));
  		}
  	}
  }
  
  static void usage(const char *cmd)
  {
  	printf("Start a XDP prog which encapsulates incoming packets
  "
  	       "in an IPv4/v6 header and XDP_TX it out.  The dst <VIP:PORT>
  "
  	       "is used to select packets to encapsulate
  
  ");
  	printf("Usage: %s [...]
  ", cmd);
  	printf("    -i <ifindex> Interface Index
  ");
  	printf("    -a <vip-service-address> IPv4 or IPv6
  ");
  	printf("    -p <vip-service-port> A port range (e.g. 433-444) is also allowed
  ");
  	printf("    -s <source-ip> Used in the IPTunnel header
  ");
  	printf("    -d <dest-ip> Used in the IPTunnel header
  ");
  	printf("    -m <dest-MAC> Used in sending the IP Tunneled pkt
  ");
  	printf("    -T <stop-after-X-seconds> Default: 0 (forever)
  ");
  	printf("    -P <IP-Protocol> Default is TCP
  ");

  	printf("    -S use skb-mode
  ");
  	printf("    -N enforce native mode
  ");

  	printf("    -h Display this help
  ");
  }
  
  static int parse_ipstr(const char *ipstr, unsigned int *addr)
  {
  	if (inet_pton(AF_INET6, ipstr, addr) == 1) {
  		return AF_INET6;
  	} else if (inet_pton(AF_INET, ipstr, addr) == 1) {
  		addr[1] = addr[2] = addr[3] = 0;
  		return AF_INET;
  	}
  
  	fprintf(stderr, "%s is an invalid IP
  ", ipstr);
  	return AF_UNSPEC;
  }
  
  static int parse_ports(const char *port_str, int *min_port, int *max_port)
  {
  	char *end;
  	long tmp_min_port;
  	long tmp_max_port;
  
  	tmp_min_port = strtol(optarg, &end, 10);
  	if (tmp_min_port < 1 || tmp_min_port > 65535) {
  		fprintf(stderr, "Invalid port(s):%s
  ", optarg);
  		return 1;
  	}
  
  	if (*end == '-') {
  		end++;
  		tmp_max_port = strtol(end, NULL, 10);
  		if (tmp_max_port < 1 || tmp_max_port > 65535) {
  			fprintf(stderr, "Invalid port(s):%s
  ", optarg);
  			return 1;
  		}
  	} else {
  		tmp_max_port = tmp_min_port;
  	}
  
  	if (tmp_min_port > tmp_max_port) {
  		fprintf(stderr, "Invalid port(s):%s
  ", optarg);
  		return 1;
  	}
  
  	if (tmp_max_port - tmp_min_port + 1 > MAX_IPTNL_ENTRIES) {
  		fprintf(stderr, "Port range (%s) is larger than %u
  ",
  			port_str, MAX_IPTNL_ENTRIES);
  		return 1;
  	}
  	*min_port = tmp_min_port;
  	*max_port = tmp_max_port;
  
  	return 0;
  }
  
  int main(int argc, char **argv)
  {
  	unsigned char opt_flags[256] = {};
  	unsigned int kill_after_s = 0;

  	const char *optstr = "i:a:p:s:d:m:T:P:SNh";

  	int min_port = 0, max_port = 0;
  	struct iptnl_info tnl = {};
  	struct rlimit r = {RLIM_INFINITY, RLIM_INFINITY};
  	struct vip vip = {};
  	char filename[256];
  	int opt;
  	int i;
  
  	tnl.family = AF_UNSPEC;
  	vip.protocol = IPPROTO_TCP;
  
  	for (i = 0; i < strlen(optstr); i++)
  		if (optstr[i] != 'h' && 'a' <= optstr[i] && optstr[i] <= 'z')
  			opt_flags[(unsigned char)optstr[i]] = 1;
  
  	while ((opt = getopt(argc, argv, optstr)) != -1) {
  		unsigned short family;
  		unsigned int *v6;
  
  		switch (opt) {
  		case 'i':
  			ifindex = atoi(optarg);
  			break;
  		case 'a':
  			vip.family = parse_ipstr(optarg, vip.daddr.v6);
  			if (vip.family == AF_UNSPEC)
  				return 1;
  			break;
  		case 'p':
  			if (parse_ports(optarg, &min_port, &max_port))
  				return 1;
  			break;
  		case 'P':
  			vip.protocol = atoi(optarg);
  			break;
  		case 's':
  		case 'd':
  			if (opt == 's')
  				v6 = tnl.saddr.v6;
  			else
  				v6 = tnl.daddr.v6;
  
  			family = parse_ipstr(optarg, v6);
  			if (family == AF_UNSPEC)
  				return 1;
  			if (tnl.family == AF_UNSPEC) {
  				tnl.family = family;
  			} else if (tnl.family != family) {
  				fprintf(stderr,
  					"The IP version of the src and dst addresses used in the IP encapsulation does not match
  ");
  				return 1;
  			}
  			break;
  		case 'm':
  			if (!ether_aton_r(optarg,
  					  (struct ether_addr *)tnl.dmac)) {
  				fprintf(stderr, "Invalid mac address:%s
  ",
  					optarg);
  				return 1;
  			}
  			break;
  		case 'T':
  			kill_after_s = atoi(optarg);
  			break;

  		case 'S':

  			xdp_flags |= XDP_FLAGS_SKB_MODE;

  			break;
  		case 'N':
  			xdp_flags |= XDP_FLAGS_DRV_MODE;

  			break;

  		default:
  			usage(argv[0]);
  			return 1;
  		}
  		opt_flags[opt] = 0;
  	}
  
  	for (i = 0; i < strlen(optstr); i++) {
  		if (opt_flags[(unsigned int)optstr[i]]) {
  			fprintf(stderr, "Missing argument -%c
  ", optstr[i]);
  			usage(argv[0]);
  			return 1;
  		}
  	}
  
  	if (setrlimit(RLIMIT_MEMLOCK, &r)) {
  		perror("setrlimit(RLIMIT_MEMLOCK, RLIM_INFINITY)");
  		return 1;
  	}
  
  	snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
  
  	if (load_bpf_file(filename)) {
  		printf("%s", bpf_log_buf);
  		return 1;
  	}
  
  	if (!prog_fd[0]) {
  		printf("load_bpf_file: %s
  ", strerror(errno));
  		return 1;
  	}
  
  	signal(SIGINT, int_exit);

  	signal(SIGTERM, int_exit);

  
  	while (min_port <= max_port) {
  		vip.dport = htons(min_port++);

  		if (bpf_map_update_elem(map_fd[1], &vip, &tnl, BPF_NOEXIST)) {
  			perror("bpf_map_update_elem(&vip2tnl)");

  			return 1;
  		}
  	}

  	if (set_link_xdp_fd(ifindex, prog_fd[0], xdp_flags) < 0) {

  		printf("link set xdp fd failed
  ");
  		return 1;
  	}
  
  	poll_stats(kill_after_s);

  	set_link_xdp_fd(ifindex, -1, xdp_flags);

  
  	return 0;
  }