/* arp.c - manipulate the system ARP cache
 *
 * Copyright 2014 Sandeep Sharma <sandeep.jack2756@gmail.com>
 * Copyright 2014 Kyungwan Han <asura321@gamil.com>
 * No Standard

USE_ARP(NEWTOY(arp, "vi:nDsdap:A:H:[+Ap][!sd]", TOYFLAG_USR|TOYFLAG_BIN))

config ARP
  bool "arp"
  default n
  help
    usage: arp
    [-vn] [-H HWTYPE] [-i IF] -a [HOSTNAME]
    [-v]              [-i IF] -d HOSTNAME [pub]
    [-v]  [-H HWTYPE] [-i IF] -s HOSTNAME HWADDR [temp]
    [-v]  [-H HWTYPE] [-i IF] -s HOSTNAME HWADDR [netmask MASK] pub
    [-v]  [-H HWTYPE] [-i IF] -Ds HOSTNAME IFACE [netmask MASK] pub

    Manipulate ARP cache.

    -a	Display (all) hosts
    -s	Set new ARP entry
    -d	Delete a specified entry
    -v	Verbose
    -n	Don't resolve names
    -i IFACE	Network interface
    -D	Read <hwaddr> from given device
    -A,-p AF	Protocol family
    -H HWTYPE	Hardware address type

*/

#define FOR_arp
#include "toys.h"
#include <net/if_arp.h>

GLOBALS(
    char *hw_type;
    char *af_type_A;
    char *af_type_p;
    char *interface;

    int sockfd;
    char *device;
)

struct arpreq req;

struct type {
  char *name;
  int val;
};

struct type hwtype[] = {
  {"ether", ARPHRD_ETHER },
  {"loop" ,ARPHRD_LOOPBACK},
  {"ppp" ,ARPHRD_PPP},
  {"infiniband" ,ARPHRD_INFINIBAND},
  {NULL, -1},
};

struct type aftype[] = {
  {"inet", AF_INET },
  {"inet6" ,AF_INET6},
  {"unspec" ,AF_UNSPEC},
  {NULL, -1},
};

struct type flag_type[] = {
  {"PERM", ATF_PERM },
  {"PUB" ,ATF_PUBL},
  {"DONTPUB" ,ATF_DONTPUB},
  {"TRAIL" ,ATF_USETRAILERS},
  {NULL, -1},
};

static int get_index(struct type arr[], char *name)
{
  int i;

  for (i = 0; arr[i].name; i++)
    if (!strcmp(arr[i].name, name)) break;
  return arr[i].val;
}

static void resolve_host(char *host, struct sockaddr *sa)
{
  struct addrinfo *ai = xgetaddrinfo(host, NULL, AF_INET, SOCK_STREAM, 0, 0);

  memcpy(sa, ai->ai_addr, ai->ai_addrlen);
  freeaddrinfo(ai);
}

static void check_flags(int *i, char** argv)
{
  struct sockaddr sa;
  int flag = *i, j;
  struct flags {
    char *name;
    int or, flag;
  } f[] = {
    {"pub",  1 ,ATF_PUBL},
    {"priv", 0 ,~ATF_PUBL},
    {"trail", 1, ATF_USETRAILERS},
    {"temp", 0, ~ATF_PERM},
    {"dontpub",1, ATF_DONTPUB},
  };

  for (;*argv; argv++) {
    for (j = 0;  j < ARRAY_LEN(f); j++) {
      if (!strcmp(*argv, f[j].name)) {
        (f[j].or) ?(flag |= f[j].flag):(flag &= f[j].flag);
        break;
      }
    }
    if (j > 4 && !strcmp(*argv, "netmask")) {
      if (!*++argv) error_exit("NULL netmask");
      if (strcmp(*argv, "255.255.255.255")) {
        resolve_host(toys.optargs[0], &sa);
        memcpy(&req.arp_netmask, &sa, sizeof(sa));
        flag |= ATF_NETMASK;
      } else argv++;
    } else if (j > 4 && !strcmp(*argv, "dev")) {
      if (!*++argv) error_exit("NULL dev");
      TT.device = *argv;
    } else if (j > 4) error_exit("invalid arg");
  }
  *i = flag;
}

static int set_entry(void)
{
  int flags = 0;

  if (!toys.optargs[1]) error_exit("bad syntax");

  if (!FLAG(D)) {
    char *ptr = toys.optargs[1];
    char *p = ptr, *hw_addr = req.arp_ha.sa_data;

    while (*hw_addr && (p-ptr) < 6) {
      int val, len;

      if (*hw_addr == ':') hw_addr++;
      if (!sscanf(hw_addr, "%2x%n", &val, &len)) break;
      hw_addr += len;
      *p++ = val;
    }

    if ((p-ptr) != 6 || *hw_addr)
      error_exit("bad hw addr '%s'", req.arp_ha.sa_data);
  } else {
    struct ifreq ifre;

    xstrncpy(ifre.ifr_name, toys.optargs[1], IFNAMSIZ);
    xioctl(TT.sockfd, SIOCGIFHWADDR, &ifre);
    if (FLAG(H) && ifre.ifr_hwaddr.sa_family != ARPHRD_ETHER)
      error_exit("protocol type mismatch");
    memcpy(&req.arp_ha, &(ifre.ifr_hwaddr), sizeof(req.arp_ha));
  }

  flags = ATF_PERM | ATF_COM;
  if (toys.optargs[2]) check_flags(&flags, (toys.optargs+2));
  req.arp_flags = flags;
  xstrncpy(req.arp_dev, TT.device, sizeof(req.arp_dev));
  xioctl(TT.sockfd, SIOCSARP, &req);

  if (FLAG(v)) xprintf("Entry set for %s\n", toys.optargs[0]);
  return 0;
}

static int ip_to_host(struct sockaddr *sa, int flag)
{
  int status = 0;
  char hbuf[NI_MAXHOST] = {0,}, sbuf[NI_MAXSERV] = {0,};
  socklen_t len = sizeof(struct sockaddr_in6);

  *toybuf = 0;
  if (!(status = getnameinfo(sa, len, hbuf, sizeof(hbuf), sbuf,
          sizeof(sbuf), flag))) {
    strcpy(toybuf, hbuf);
    return 0;
  }
  return 1;
}

static int delete_entry(void)
{
  int flags = ATF_PERM;

  if (toys.optargs[1]) check_flags(&flags, (toys.optargs+1));
  req.arp_flags = flags;
  xstrncpy(req.arp_dev, TT.device, sizeof(req.arp_dev));
  xioctl(TT.sockfd, SIOCDARP, &req);

  if (FLAG(v)) xprintf("Delete entry for  %s\n", toys.optargs[0]);
  return 0;
}

void arp_main(void)
{
  struct sockaddr sa;
  char ip[16], hw_addr[30], mask[16], dev[16], *host_ip = NULL;
  FILE *fp;
  int h_type, type, flag, i, entries = 0, disp = 0;

  TT.device = "";
  memset(&sa, 0, sizeof(sa));
  TT.sockfd = xsocket(AF_INET, SOCK_STREAM, 0);

  if (FLAG(A) || FLAG(p)) {
    if ((type = get_index(aftype,
            (TT.af_type_A)?TT.af_type_A:TT.af_type_p)) != AF_INET)
      error_exit((type != -1)?"only inet supported by kernel":"unknown family");
  }

  req.arp_ha.sa_family = ARPHRD_ETHER;
  if (FLAG(H)) {
    if ((type = get_index(hwtype, TT.hw_type)) != ARPHRD_ETHER)
      error_exit((type != -1)?"h/w type not supported":"unknown h/w type");
    req.arp_ha.sa_family = type;
  }

  if (FLAG(s) || FLAG(d)) {
    if (!toys.optargs[0]) error_exit("-%c needs a host name", FLAG(d)?'d':'s');
    resolve_host(toys.optargs[0], &sa);
    memcpy(&req.arp_pa, &sa, sizeof(struct sockaddr));

    if (FLAG(s) && !set_entry()) return;
    if (FLAG(d) && !delete_entry()) return;
  }

  // Show arp cache.

  if (toys.optargs[0]) {
    resolve_host(toys.optargs[0], &sa);
    ip_to_host(&sa, NI_NUMERICHOST);
    host_ip = xstrdup(toybuf);
  }

  fp = xfopen("/proc/net/arp", "r");
  fgets(toybuf, sizeof(toybuf), fp); // Skip header.
  while (fscanf(fp, "%15s 0x%x 0x%x %29s %15s %15s",
                ip, &h_type, &flag, hw_addr, mask, dev) == 6) {
    char *host_name = "?";

    entries++;
    if ((FLAG(H) && get_index(hwtype, TT.hw_type) != h_type) ||
      (FLAG(i) && strcmp(TT.interface, dev)) ||
      (toys.optargs[0] && strcmp(host_ip, ip))) {
      continue;
    }

    resolve_host(ip, &sa);
    if (FLAG(n)) ip_to_host(&sa, NI_NUMERICHOST);
    else if (!ip_to_host(&sa, NI_NAMEREQD)) host_name = toybuf;

    disp++;
    printf("%s (%s) at" , host_name, ip);

    for (i = 0; hwtype[i].name; i++)
      if (hwtype[i].val & h_type) break;
    if (!hwtype[i].name) error_exit("unknown h/w type");

    if (!(flag & ATF_COM)) {
      if ((flag & ATF_PUBL)) printf(" *");
      else printf(" <incomplete>");
    } else printf(" %s [%s]", hw_addr, hwtype[i].name);

    if (flag & ATF_NETMASK) printf("netmask %s ", mask);

    for (i = 0; flag_type[i].name; i++)
      if (flag_type[i].val & flag) printf(" %s", flag_type[i].name);

    printf(" on %s\n", dev);
  }

  if (FLAG(v))
    xprintf("Entries: %d\tSkipped: %d\tFound: %d\n",
        entries, entries - disp, disp);
  if (toys.optargs[0] && !disp)
    xprintf("%s (%s) -- no entry\n", toys.optargs[0], host_ip);

  if (CFG_TOYBOX_FREE) {
    free(host_ip);
    fclose(fp);
  }
}