/* vi: set sw=4 ts=4: */
/*
 * arp.c - Manipulate the system ARP cache
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 *
 * Author: Fred N. van Kempen, <waltje at uwalt.nl.mugnet.org>
 * Busybox port: Paul van Gool <pvangool at mimotech.com>
 *
 * modified for getopt32 by Arne Bernin <arne [at] alamut.de>
 */
//config:config ARP
//config:       bool "arp (11 kb)"
//config:       default y
//config:       select PLATFORM_LINUX
//config:       help
//config:       Manipulate the system ARP cache.

//applet:IF_ARP(APPLET(arp, BB_DIR_SBIN, BB_SUID_DROP))

//kbuild:lib-$(CONFIG_ARP) += arp.o interface.o

//usage:#define arp_trivial_usage
//usage:     "\n[-vn]   [-H HWTYPE] [-i IF] -a [HOSTNAME]"
//usage:     "\n[-v]                [-i IF] -d HOSTNAME [pub]"
//usage:     "\n[-v]    [-H HWTYPE] [-i IF] -s HOSTNAME HWADDR [temp]"
//usage:     "\n[-v]    [-H HWTYPE] [-i IF] -s HOSTNAME HWADDR [netmask MASK] pub"
//usage:     "\n[-v]    [-H HWTYPE] [-i IF] -Ds HOSTNAME IFACE [netmask MASK] pub"
//usage:#define arp_full_usage "\n\n"
//usage:       "Manipulate ARP cache\n"
//usage:       "\n      -a              Display (all) hosts"
//usage:       "\n      -d              Delete ARP entry"
//usage:       "\n      -s              Set new entry"
//usage:       "\n      -v              Verbose"
//usage:       "\n      -n              Don't resolve names"
//usage:       "\n      -i IF           Network interface"
//usage:       "\n      -D              Read HWADDR from IFACE"
//usage:       "\n      -A,-p AF        Protocol family"
//usage:       "\n      -H HWTYPE       Hardware address type"

#include "libbb.h"
#include "common_bufsiz.h"
#include "inet_common.h"

#include <arpa/inet.h>
#include <net/if.h>
#include <net/if_arp.h>
#include <netinet/ether.h>
#include <netpacket/packet.h>

#define DEBUG 0

#define DFLT_AF "inet"
#define DFLT_HW "ether"

enum {
        ARP_OPT_A = (1 << 0),
        ARP_OPT_p = (1 << 1),
        ARP_OPT_H = (1 << 2),
        ARP_OPT_t = (1 << 3),
        ARP_OPT_i = (1 << 4),
        ARP_OPT_a = (1 << 5),
        ARP_OPT_d = (1 << 6),
        ARP_OPT_n = (1 << 7), /* do not resolve addresses */
        ARP_OPT_D = (1 << 8), /* HW-address is devicename */
        ARP_OPT_s = (1 << 9),
        ARP_OPT_v = (1 << 10) * DEBUG, /* debugging output flag */
};

enum {
        sockfd = 3, /* active socket descriptor */
};

struct globals {
        const struct aftype *ap; /* current address family */
        const struct hwtype *hw; /* current hardware type */
        const char *device;      /* current device */
        smallint hw_set;         /* flag if hw-type was set (-H) */
} FIX_ALIASING;
#define G (*(struct globals*)bb_common_bufsiz1)
#define ap         (G.ap        )
#define hw         (G.hw        )
#define device     (G.device    )
#define hw_set     (G.hw_set    )
#define INIT_G() do { \
        setup_common_bufsiz(); \
        device = ""; \
} while (0)


static const char options[] ALIGN1 =
        "pub\0"
        "priv\0"
        "temp\0"
        "trail\0"
        "dontpub\0"
        "auto\0"
        "dev\0"
        "netmask\0";

/* Delete an entry from the ARP cache. */
/* Called only from main, once */
static int arp_del(char **args)
{
        char *host;
        struct arpreq req;
        struct sockaddr sa;
        int flags = 0;
        int err;

        memset(&req, 0, sizeof(req));

        /* Resolve the host name. */
        host = *args;
        if (ap->input(host, &sa) < 0) {
                bb_herror_msg_and_die("%s", host);
        }

        /* If a host has more than one address, use the correct one! */
        memcpy(&req.arp_pa, &sa, sizeof(struct sockaddr));

        if (hw_set)
                req.arp_ha.sa_family = hw->type;

        req.arp_flags = ATF_PERM;
        args++;
        while (*args != NULL) {
                switch (index_in_strings(options, *args)) {
                case 0: /* "pub" */
                        flags |= 1;
                        args++;
                        break;
                case 1: /* "priv" */
                        flags |= 2;
                        args++;
                        break;
                case 2: /* "temp" */
                        req.arp_flags &= ~ATF_PERM;
                        args++;
                        break;
                case 3: /* "trail" */
                        req.arp_flags |= ATF_USETRAILERS;
                        args++;
                        break;
                case 4: /* "dontpub" */
#ifdef HAVE_ATF_DONTPUB
                        req.arp_flags |= ATF_DONTPUB;
#else
                        bb_error_msg("feature ATF_DONTPUB is not supported");
#endif
                        args++;
                        break;
                case 5: /* "auto" */
#ifdef HAVE_ATF_MAGIC
                        req.arp_flags |= ATF_MAGIC;
#else
                        bb_error_msg("feature ATF_MAGIC is not supported");
#endif
                        args++;
                        break;
                case 6: /* "dev" */
                        if (*++args == NULL)
                                bb_show_usage();
                        device = *args;
                        args++;
                        break;
                case 7: /* "netmask" */
                        if (*++args == NULL)
                                bb_show_usage();
                        if (strcmp(*args, "255.255.255.255") != 0) {
                                host = *args;
                                if (ap->input(host, &sa) < 0) {
                                        bb_herror_msg_and_die("%s", host);
                                }
                                memcpy(&req.arp_netmask, &sa, sizeof(struct sockaddr));
                                req.arp_flags |= ATF_NETMASK;
                        }
                        args++;
                        break;
                default:
                        bb_show_usage();
                        break;
                }
        }
        if (flags == 0)
                flags = 3;

        strncpy_IFNAMSIZ(req.arp_dev, device);

        err = -1;

        /* Call the kernel. */
        if (flags & 2) {
                if (option_mask32 & ARP_OPT_v)
                        bb_error_msg("SIOCDARP(nopub)");
                err = ioctl(sockfd, SIOCDARP, &req);
                if (err < 0) {
                        if (errno == ENXIO) {
                                if (flags & 1)
                                        goto nopub;
                                printf("No ARP entry for %s\n", host);
                                return -1;
                        }
                        bb_perror_msg_and_die("SIOCDARP(priv)");
                }
        }
        if ((flags & 1) && err) {
 nopub:
                req.arp_flags |= ATF_PUBL;
                if (option_mask32 & ARP_OPT_v)
                        bb_error_msg("SIOCDARP(pub)");
                if (ioctl(sockfd, SIOCDARP, &req) < 0) {
                        if (errno == ENXIO) {
                                printf("No ARP entry for %s\n", host);
                                return -1;
                        }
                        bb_perror_msg_and_die("SIOCDARP(pub)");
                }
        }
        return 0;
}

/* Get the hardware address to a specified interface name */
static void arp_getdevhw(char *ifname, struct sockaddr *sa)
{
        struct ifreq ifr;
        const struct hwtype *xhw;

        strncpy_IFNAMSIZ(ifr.ifr_name, ifname);
        ioctl_or_perror_and_die(sockfd, SIOCGIFHWADDR, &ifr,
                                        "can't get HW-Address for '%s'", ifname);
        if (hw_set && (ifr.ifr_hwaddr.sa_family != hw->type)) {
                bb_error_msg_and_die("protocol type mismatch");
        }
        memcpy(sa, &(ifr.ifr_hwaddr), sizeof(struct sockaddr));

        if (option_mask32 & ARP_OPT_v) {
                xhw = get_hwntype(ifr.ifr_hwaddr.sa_family);
                if (!xhw || !xhw->print) {
                        xhw = get_hwntype(-1);
                }
                bb_error_msg("device '%s' has HW address %s '%s'",
                                ifname, xhw->name,
                                xhw->print((unsigned char *) &ifr.ifr_hwaddr.sa_data));
        }
}

/* Set an entry in the ARP cache. */
/* Called only from main, once */
static int arp_set(char **args)
{
        char *host;
        struct arpreq req;
        struct sockaddr sa;
        int flags;

        memset(&req, 0, sizeof(req));

        host = *args++;
        if (ap->input(host, &sa) < 0) {
                bb_herror_msg_and_die("%s", host);
        }
        /* If a host has more than one address, use the correct one! */
        memcpy(&req.arp_pa, &sa, sizeof(struct sockaddr));

        /* Fetch the hardware address. */
        if (*args == NULL) {
                bb_error_msg_and_die("need hardware address");
        }
        if (option_mask32 & ARP_OPT_D) {
                arp_getdevhw(*args++, &req.arp_ha);
        } else {
                if (hw->input(*args++, &req.arp_ha) < 0) {
                        bb_error_msg_and_die("invalid hardware address");
                }
        }

        /* Check out any modifiers. */
        flags = ATF_PERM | ATF_COM;
        while (*args != NULL) {
                switch (index_in_strings(options, *args)) {
                case 0: /* "pub" */
                        flags |= ATF_PUBL;
                        args++;
                        break;
                case 1: /* "priv" */
                        flags &= ~ATF_PUBL;
                        args++;
                        break;
                case 2: /* "temp" */
                        flags &= ~ATF_PERM;
                        args++;
                        break;
                case 3: /* "trail" */
                        flags |= ATF_USETRAILERS;
                        args++;
                        break;
                case 4: /* "dontpub" */
#ifdef HAVE_ATF_DONTPUB
                        flags |= ATF_DONTPUB;
#else
                        bb_error_msg("feature ATF_DONTPUB is not supported");
#endif
                        args++;
                        break;
                case 5: /* "auto" */
#ifdef HAVE_ATF_MAGIC
                        flags |= ATF_MAGIC;
#else
                        bb_error_msg("feature ATF_MAGIC is not supported");
#endif
                        args++;
                        break;
                case 6: /* "dev" */
                        if (*++args == NULL)
                                bb_show_usage();
                        device = *args;
                        args++;
                        break;
                case 7: /* "netmask" */
                        if (*++args == NULL)
                                bb_show_usage();
                        if (strcmp(*args, "255.255.255.255") != 0) {
                                host = *args;
                                if (ap->input(host, &sa) < 0) {
                                        bb_herror_msg_and_die("%s", host);
                                }
                                memcpy(&req.arp_netmask, &sa, sizeof(struct sockaddr));
                                flags |= ATF_NETMASK;
                        }
                        args++;
                        break;
                default:
                        bb_show_usage();
                        break;
                }
        }

        /* Fill in the remainder of the request. */
        req.arp_flags = flags;

        strncpy_IFNAMSIZ(req.arp_dev, device);

        /* Call the kernel. */
        if (option_mask32 & ARP_OPT_v)
                bb_error_msg("SIOCSARP()");
        xioctl(sockfd, SIOCSARP, &req);
        return 0;
}


/* Print the contents of an ARP request block. */
static void
arp_disp(const char *name, char *ip, int type, int arp_flags,
                char *hwa, char *mask, char *dev)
{
        static const int arp_masks[] = {
                ATF_PERM, ATF_PUBL,
#ifdef HAVE_ATF_MAGIC
                ATF_MAGIC,
#endif
#ifdef HAVE_ATF_DONTPUB
                ATF_DONTPUB,
#endif
                ATF_USETRAILERS,
        };
        static const char arp_labels[] ALIGN1 = "PERM\0""PUP\0"
#ifdef HAVE_ATF_MAGIC
                "AUTO\0"
#endif
#ifdef HAVE_ATF_DONTPUB
                "DONTPUB\0"
#endif
                "TRAIL\0"
        ;

        const struct hwtype *xhw;

        xhw = get_hwntype(type);
        if (xhw == NULL)
                xhw = get_hwtype(DFLT_HW);

        printf("%s (%s) at ", name, ip);

        if (!(arp_flags & ATF_COM)) {
                if (arp_flags & ATF_PUBL)
                        printf("* ");
                else
                        printf("<incomplete> ");
        } else {
                printf("%s [%s] ", hwa, xhw->name);
        }

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

        print_flags_separated(arp_masks, arp_labels, arp_flags, " ");
        printf(" on %s\n", dev);
}

/* Display the contents of the ARP cache in the kernel. */
/* Called only from main, once */
static int arp_show(char *name)
{
        const char *host;
        const char *hostname;
        FILE *fp;
        struct sockaddr sa;
        int type, flags;
        int num;
        unsigned entries = 0, shown = 0;
        char ip[128];
        char hwa[128];
        char mask[128];
        char line[128];
        char dev[128];

        host = NULL;
        if (name != NULL) {
                /* Resolve the host name. */
                if (ap->input(name, &sa) < 0) {
                        bb_herror_msg_and_die("%s", name);
                }
                host = xstrdup(ap->sprint(&sa, 1));
        }
        fp = xfopen_for_read("/proc/net/arp");
        /* Bypass header -- read one line */
        fgets(line, sizeof(line), fp);

        /* Read the ARP cache entries. */
        while (fgets(line, sizeof(line), fp)) {

                mask[0] = '-'; mask[1] = '\0';
                dev[0] = '-'; dev[1] = '\0';
                /* All these strings can't overflow
                 * because fgets above reads limited amount of data */
                num = sscanf(line, "%s 0x%x 0x%x %s %s %s\n",
                                        ip, &type, &flags, hwa, mask, dev);
                if (num < 4)
                        break;

                entries++;
                /* if the user specified hw-type differs, skip it */
                if (hw_set && (type != hw->type))
                        continue;

                /* if the user specified address differs, skip it */
                if (host && strcmp(ip, host) != 0)
                        continue;

                /* if the user specified device differs, skip it */
                if (device[0] && strcmp(dev, device) != 0)
                        continue;

                shown++;
                /* This IS ugly but it works -be */
                hostname = "?";
                if (!(option_mask32 & ARP_OPT_n)) {
                        if (ap->input(ip, &sa) < 0)
                                hostname = ip;
                        else
                                hostname = ap->sprint(&sa, (option_mask32 & ARP_OPT_n) | 0x8000);
                        if (strcmp(hostname, ip) == 0)
                                hostname = "?";
                }

                arp_disp(hostname, ip, type, flags, hwa, mask, dev);
        }
        if (option_mask32 & ARP_OPT_v)
                printf("Entries: %u\tSkipped: %u\tFound: %u\n",
                                entries, entries - shown, shown);

        if (!shown) {
                if (hw_set || host || device[0])
                        printf("No match found in %u entries\n", entries);
        }
        if (ENABLE_FEATURE_CLEAN_UP) {
                free((char*)host);
                fclose(fp);
        }
        return 0;
}

int arp_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int arp_main(int argc UNUSED_PARAM, char **argv)
{
        const char *hw_type;
        const char *protocol;
        unsigned opts;

        INIT_G();

        xmove_fd(xsocket(AF_INET, SOCK_DGRAM, 0), sockfd);

        ap = get_aftype(DFLT_AF);
        /* Defaults are always supported */
        //if (!ap)
        //      bb_error_msg_and_die("%s: %s not supported", DFLT_AF, "address family");
        hw = get_hwtype(DFLT_HW);
        //if (!hw)
        //      bb_error_msg_and_die("%s: %s not supported", DFLT_HW, "hardware type");

        opts = getopt32(argv, "A:p:H:t:i:adnDsv", &protocol, &protocol,
                                 &hw_type, &hw_type, &device);
        argv += optind;
        if (opts & (ARP_OPT_A | ARP_OPT_p)) {
                ap = get_aftype(protocol);
                if (!ap)
                        bb_error_msg_and_die("%s: unknown %s", protocol, "address family");
        }
        if (opts & (ARP_OPT_H | ARP_OPT_t)) {
                hw = get_hwtype(hw_type);
                if (!hw)
                        bb_error_msg_and_die("%s: unknown %s", hw_type, "hardware type");
                hw_set = 1;
        }
        //if (opts & ARP_OPT_i)... -i

        if (ap->af != AF_INET) {
                bb_error_msg_and_die("%s: kernel only supports 'inet'", ap->name);
        }
        if (hw->alen <= 0) {
                bb_error_msg_and_die("%s: %s without ARP support",
                                hw->name, "hardware type");
        }

        /* Now see what we have to do here... */
        if (opts & (ARP_OPT_d | ARP_OPT_s)) {
                if (argv[0] == NULL)
                        bb_error_msg_and_die("need host name");
                if (opts & ARP_OPT_s)
                        return arp_set(argv);
                return arp_del(argv);
        }

        //if (opts & ARP_OPT_a) - default
        return arp_show(argv[0]);
}