/* 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]); }