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Editing: arp.c
/*- * SPDX-License-Identifier: BSD-3-Clause * * Copyright (c) 1984, 1993 * The Regents of the University of California. All rights reserved. * * This code is derived from software contributed to Berkeley by * Sun Microsystems, Inc. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #if 0 #ifndef lint static char const copyright[] = "@(#) Copyright (c) 1984, 1993\n\ The Regents of the University of California. All rights reserved.\n"; #endif /* not lint */ #ifndef lint static char const sccsid[] = "@(#)from: arp.c 8.2 (Berkeley) 1/2/94"; #endif /* not lint */ #endif #include <sys/cdefs.h> __FBSDID("$FreeBSD$"); /* * arp - display, set, and delete arp table entries */ #include <sys/param.h> #include <sys/file.h> #include <sys/socket.h> #include <sys/sockio.h> #include <sys/sysctl.h> #include <sys/ioctl.h> #include <sys/time.h> #include <net/if.h> #include <net/if_dl.h> #include <net/if_types.h> #include <net/route.h> #include <netinet/in.h> #include <netinet/if_ether.h> #include <arpa/inet.h> #include <ctype.h> #include <err.h> #include <errno.h> #include <netdb.h> #include <nlist.h> #include <paths.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <strings.h> #include <unistd.h> #include <libxo/xo.h> typedef void (action_fn)(struct sockaddr_dl *sdl, struct sockaddr_in *s_in, struct rt_msghdr *rtm); static int search(u_long addr, action_fn *action); static action_fn print_entry; static action_fn nuke_entry; static int delete(char *host); static void usage(void); static int set(int argc, char **argv); static int get(char *host); static int file(char *name); static struct rt_msghdr *rtmsg(int cmd, struct sockaddr_in *dst, struct sockaddr_dl *sdl); static int get_ether_addr(in_addr_t ipaddr, struct ether_addr *hwaddr); static struct sockaddr_in *getaddr(char *host); static int valid_type(int type); static int nflag; /* no reverse dns lookups */ static char *rifname; static time_t expire_time; static int flags, doing_proxy; struct if_nameindex *ifnameindex; /* which function we're supposed to do */ #define F_GET 1 #define F_SET 2 #define F_FILESET 3 #define F_REPLACE 4 #define F_DELETE 5 #define SETFUNC(f) { if (func) usage(); func = (f); } #define ARP_XO_VERSION "1" int main(int argc, char *argv[]) { int ch, func = 0; int rtn = 0; int aflag = 0; /* do it for all entries */ argc = xo_parse_args(argc, argv); if (argc < 0) exit(1); while ((ch = getopt(argc, argv, "andfsSi:")) != -1) switch(ch) { case 'a': aflag = 1; break; case 'd': SETFUNC(F_DELETE); break; case 'n': nflag = 1; break; case 'S': SETFUNC(F_REPLACE); break; case 's': SETFUNC(F_SET); break; case 'f' : SETFUNC(F_FILESET); break; case 'i': rifname = optarg; break; case '?': default: usage(); } argc -= optind; argv += optind; if (!func) func = F_GET; if (rifname) { if (func != F_GET && !(func == F_DELETE && aflag)) xo_errx(1, "-i not applicable to this operation"); if (if_nametoindex(rifname) == 0) { if (errno == ENXIO) xo_errx(1, "interface %s does not exist", rifname); else xo_err(1, "if_nametoindex(%s)", rifname); } } switch (func) { case F_GET: if (aflag) { if (argc != 0) usage(); xo_set_version(ARP_XO_VERSION); xo_open_container("arp"); xo_open_list("arp-cache"); search(0, print_entry); xo_close_list("arp-cache"); xo_close_container("arp"); xo_finish(); } else { if (argc != 1) usage(); rtn = get(argv[0]); } break; case F_SET: case F_REPLACE: if (argc < 2 || argc > 6) usage(); if (func == F_REPLACE) (void)delete(argv[0]); rtn = set(argc, argv) ? 1 : 0; break; case F_DELETE: if (aflag) { if (argc != 0) usage(); search(0, nuke_entry); } else { if (argc != 1) usage(); rtn = delete(argv[0]); } break; case F_FILESET: if (argc != 1) usage(); rtn = file(argv[0]); break; } if (ifnameindex != NULL) if_freenameindex(ifnameindex); return (rtn); } /* * Process a file to set standard arp entries */ static int file(char *name) { FILE *fp; int i, retval; char line[100], arg[5][50], *args[5], *p; if ((fp = fopen(name, "r")) == NULL) xo_err(1, "cannot open %s", name); args[0] = &arg[0][0]; args[1] = &arg[1][0]; args[2] = &arg[2][0]; args[3] = &arg[3][0]; args[4] = &arg[4][0]; retval = 0; while(fgets(line, sizeof(line), fp) != NULL) { if ((p = strchr(line, '#')) != NULL) *p = '\0'; for (p = line; isblank(*p); p++); if (*p == '\n' || *p == '\0') continue; i = sscanf(p, "%49s %49s %49s %49s %49s", arg[0], arg[1], arg[2], arg[3], arg[4]); if (i < 2) { xo_warnx("bad line: %s", line); retval = 1; continue; } if (set(i, args)) retval = 1; } fclose(fp); return (retval); } /* * Given a hostname, fills up a (static) struct sockaddr_in with * the address of the host and returns a pointer to the * structure. */ static struct sockaddr_in * getaddr(char *host) { struct hostent *hp; static struct sockaddr_in reply; bzero(&reply, sizeof(reply)); reply.sin_len = sizeof(reply); reply.sin_family = AF_INET; reply.sin_addr.s_addr = inet_addr(host); if (reply.sin_addr.s_addr == INADDR_NONE) { if (!(hp = gethostbyname(host))) { xo_warnx("%s: %s", host, hstrerror(h_errno)); return (NULL); } bcopy((char *)hp->h_addr, (char *)&reply.sin_addr, sizeof reply.sin_addr); } return (&reply); } /* * Returns true if the type is a valid one for ARP. */ static int valid_type(int type) { switch (type) { case IFT_ETHER: case IFT_FDDI: case IFT_INFINIBAND: case IFT_ISO88023: case IFT_ISO88024: case IFT_L2VLAN: case IFT_BRIDGE: return (1); default: return (0); } } /* * Set an individual arp entry */ static int set(int argc, char **argv) { struct sockaddr_in *addr; struct sockaddr_in *dst; /* what are we looking for */ struct sockaddr_dl *sdl; struct rt_msghdr *rtm; struct ether_addr *ea; char *host = argv[0], *eaddr = argv[1]; struct sockaddr_dl sdl_m; argc -= 2; argv += 2; bzero(&sdl_m, sizeof(sdl_m)); sdl_m.sdl_len = sizeof(sdl_m); sdl_m.sdl_family = AF_LINK; dst = getaddr(host); if (dst == NULL) return (1); doing_proxy = flags = expire_time = 0; while (argc-- > 0) { if (strcmp(argv[0], "temp") == 0) { struct timespec tp; int max_age; size_t len = sizeof(max_age); clock_gettime(CLOCK_MONOTONIC, &tp); if (sysctlbyname("net.link.ether.inet.max_age", &max_age, &len, NULL, 0) != 0) xo_err(1, "sysctlbyname"); expire_time = tp.tv_sec + max_age; } else if (strcmp(argv[0], "pub") == 0) { flags |= RTF_ANNOUNCE; doing_proxy = 1; if (argc && strcmp(argv[1], "only") == 0) { /* * Compatibility: in pre FreeBSD 8 times * the "only" keyword used to mean that * an ARP entry should be announced, but * not installed into routing table. */ argc--; argv++; } } else if (strcmp(argv[0], "blackhole") == 0) { if (flags & RTF_REJECT) { xo_errx(1, "Choose one of blackhole or reject, " "not both."); } flags |= RTF_BLACKHOLE; } else if (strcmp(argv[0], "reject") == 0) { if (flags & RTF_BLACKHOLE) { xo_errx(1, "Choose one of blackhole or reject, " "not both."); } flags |= RTF_REJECT; } else { xo_warnx("Invalid parameter '%s'", argv[0]); usage(); } argv++; } ea = (struct ether_addr *)LLADDR(&sdl_m); if (doing_proxy && !strcmp(eaddr, "auto")) { if (!get_ether_addr(dst->sin_addr.s_addr, ea)) { xo_warnx("no interface found for %s", inet_ntoa(dst->sin_addr)); return (1); } sdl_m.sdl_alen = ETHER_ADDR_LEN; } else { struct ether_addr *ea1 = ether_aton(eaddr); if (ea1 == NULL) { xo_warnx("invalid Ethernet address '%s'", eaddr); return (1); } else { *ea = *ea1; sdl_m.sdl_alen = ETHER_ADDR_LEN; } } /* * In the case a proxy-arp entry is being added for * a remote end point, the RTF_ANNOUNCE flag in the * RTM_GET command is an indication to the kernel * routing code that the interface associated with * the prefix route covering the local end of the * PPP link should be returned, on which ARP applies. */ rtm = rtmsg(RTM_GET, dst, NULL); if (rtm == NULL) { xo_warn("%s", host); return (1); } addr = (struct sockaddr_in *)(rtm + 1); sdl = (struct sockaddr_dl *)(SA_SIZE(addr) + (char *)addr); if ((sdl->sdl_family != AF_LINK) || (rtm->rtm_flags & RTF_GATEWAY) || !valid_type(sdl->sdl_type)) { xo_warnx("cannot intuit interface index and type for %s", host); return (1); } sdl_m.sdl_type = sdl->sdl_type; sdl_m.sdl_index = sdl->sdl_index; return (rtmsg(RTM_ADD, dst, &sdl_m) == NULL); } /* * Display an individual arp entry */ static int get(char *host) { struct sockaddr_in *addr; int found; addr = getaddr(host); if (addr == NULL) return (1); xo_set_version(ARP_XO_VERSION); xo_open_container("arp"); xo_open_list("arp-cache"); found = search(addr->sin_addr.s_addr, print_entry); if (found == 0) { xo_emit("{d:hostname/%s} ({d:ip-address/%s}) -- no entry", host, inet_ntoa(addr->sin_addr)); if (rifname) xo_emit(" on {d:interface/%s}", rifname); xo_emit("\n"); } xo_close_list("arp-cache"); xo_close_container("arp"); xo_finish(); return (found == 0); } /* * Delete an arp entry */ static int delete(char *host) { struct sockaddr_in *addr, *dst; struct rt_msghdr *rtm; struct sockaddr_dl *sdl; dst = getaddr(host); if (dst == NULL) return (1); /* * Perform a regular entry delete first. */ flags &= ~RTF_ANNOUNCE; for (;;) { /* try twice */ rtm = rtmsg(RTM_GET, dst, NULL); if (rtm == NULL) { xo_warn("%s", host); return (1); } addr = (struct sockaddr_in *)(rtm + 1); sdl = (struct sockaddr_dl *)(SA_SIZE(addr) + (char *)addr); /* * With the new L2/L3 restructure, the route * returned is a prefix route. The important * piece of information from the previous * RTM_GET is the interface index. In the * case of ECMP, the kernel will traverse * the route group for the given entry. */ if (sdl->sdl_family == AF_LINK && !(rtm->rtm_flags & RTF_GATEWAY) && valid_type(sdl->sdl_type) ) { addr->sin_addr.s_addr = dst->sin_addr.s_addr; break; } /* * Regular entry delete failed, now check if there * is a proxy-arp entry to remove. */ if (flags & RTF_ANNOUNCE) { xo_warnx("delete: cannot locate %s", host); return (1); } flags |= RTF_ANNOUNCE; } rtm->rtm_flags |= RTF_LLDATA; if (rtmsg(RTM_DELETE, dst, NULL) != NULL) { printf("%s (%s) deleted\n", host, inet_ntoa(addr->sin_addr)); return (0); } return (1); } /* * Search the arp table and do some action on matching entries */ static int search(u_long addr, action_fn *action) { int mib[6]; size_t needed; char *lim, *buf, *next; struct rt_msghdr *rtm; struct sockaddr_in *sin2; struct sockaddr_dl *sdl; char ifname[IF_NAMESIZE]; int st, found_entry = 0; mib[0] = CTL_NET; mib[1] = PF_ROUTE; mib[2] = 0; mib[3] = AF_INET; mib[4] = NET_RT_FLAGS; #ifdef RTF_LLINFO mib[5] = RTF_LLINFO; #else mib[5] = 0; #endif if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0) xo_err(1, "route-sysctl-estimate"); if (needed == 0) /* empty table */ return 0; buf = NULL; for (;;) { buf = reallocf(buf, needed); if (buf == NULL) xo_errx(1, "could not reallocate memory"); st = sysctl(mib, 6, buf, &needed, NULL, 0); if (st == 0 || errno != ENOMEM) break; needed += needed / 8; } if (st == -1) xo_err(1, "actual retrieval of routing table"); lim = buf + needed; for (next = buf; next < lim; next += rtm->rtm_msglen) { rtm = (struct rt_msghdr *)next; sin2 = (struct sockaddr_in *)(rtm + 1); sdl = (struct sockaddr_dl *)((char *)sin2 + SA_SIZE(sin2)); if (rifname && if_indextoname(sdl->sdl_index, ifname) && strcmp(ifname, rifname)) continue; if (addr) { if (addr != sin2->sin_addr.s_addr) continue; found_entry = 1; } (*action)(sdl, sin2, rtm); } free(buf); return (found_entry); } /* * Display an arp entry */ static void print_entry(struct sockaddr_dl *sdl, struct sockaddr_in *addr, struct rt_msghdr *rtm) { const char *host; struct hostent *hp; struct if_nameindex *p; if (ifnameindex == NULL) if ((ifnameindex = if_nameindex()) == NULL) xo_err(1, "cannot retrieve interface names"); xo_open_instance("arp-cache"); if (nflag == 0) hp = gethostbyaddr((caddr_t)&(addr->sin_addr), sizeof addr->sin_addr, AF_INET); else hp = 0; if (hp) host = hp->h_name; else { host = "?"; if (h_errno == TRY_AGAIN) nflag = 1; } xo_emit("{:hostname/%s} ({:ip-address/%s}) at ", host, inet_ntoa(addr->sin_addr)); if (sdl->sdl_alen) { if ((sdl->sdl_type == IFT_ETHER || sdl->sdl_type == IFT_L2VLAN || sdl->sdl_type == IFT_BRIDGE) && sdl->sdl_alen == ETHER_ADDR_LEN) xo_emit("{:mac-address/%s}", ether_ntoa((struct ether_addr *)LLADDR(sdl))); else { int n = sdl->sdl_nlen > 0 ? sdl->sdl_nlen + 1 : 0; xo_emit("{:mac-address/%s}", link_ntoa(sdl) + n); } } else xo_emit("{d:/(incomplete)}{en:incomplete/true}"); for (p = ifnameindex; p && p->if_index && p->if_name; p++) { if (p->if_index == sdl->sdl_index) { xo_emit(" on {:interface/%s}", p->if_name); break; } } if (rtm->rtm_rmx.rmx_expire == 0) xo_emit("{d:/ permanent}{en:permanent/true}"); else { static struct timespec tp; if (tp.tv_sec == 0) clock_gettime(CLOCK_MONOTONIC, &tp); if ((expire_time = rtm->rtm_rmx.rmx_expire - tp.tv_sec) > 0) xo_emit(" expires in {:expires/%d} seconds", (int)expire_time); else xo_emit("{d:/ expired}{en:expired/true}"); } if (rtm->rtm_flags & RTF_ANNOUNCE) xo_emit("{d:/ published}{en:published/true}"); switch(sdl->sdl_type) { case IFT_ETHER: xo_emit(" [{:type/ethernet}]"); break; case IFT_FDDI: xo_emit(" [{:type/fddi}]"); break; case IFT_ATM: xo_emit(" [{:type/atm}]"); break; case IFT_L2VLAN: xo_emit(" [{:type/vlan}]"); break; case IFT_IEEE1394: xo_emit(" [{:type/firewire}]"); break; case IFT_BRIDGE: xo_emit(" [{:type/bridge}]"); break; case IFT_INFINIBAND: xo_emit(" [{:type/infiniband}]"); break; default: break; } xo_emit("\n"); xo_close_instance("arp-cache"); } /* * Nuke an arp entry */ static void nuke_entry(struct sockaddr_dl *sdl __unused, struct sockaddr_in *addr, struct rt_msghdr *rtm) { char ip[20]; if (rtm->rtm_flags & RTF_PINNED) return; snprintf(ip, sizeof(ip), "%s", inet_ntoa(addr->sin_addr)); delete(ip); } static void usage(void) { fprintf(stderr, "%s\n%s\n%s\n%s\n%s\n%s\n%s\n", "usage: arp [-n] [-i interface] hostname", " arp [-n] [-i interface] -a", " arp -d hostname [pub]", " arp -d [-i interface] -a", " arp -s hostname ether_addr [temp] [reject | blackhole] [pub [only]]", " arp -S hostname ether_addr [temp] [reject | blackhole] [pub [only]]", " arp -f filename"); exit(1); } static struct rt_msghdr * rtmsg(int cmd, struct sockaddr_in *dst, struct sockaddr_dl *sdl) { static int seq; int rlen; int l; static int s = -1; static pid_t pid; static struct { struct rt_msghdr m_rtm; char m_space[512]; } m_rtmsg; struct rt_msghdr *rtm = &m_rtmsg.m_rtm; char *cp = m_rtmsg.m_space; if (s < 0) { /* first time: open socket, get pid */ s = socket(PF_ROUTE, SOCK_RAW, 0); if (s < 0) xo_err(1, "socket"); pid = getpid(); } errno = 0; /* * XXX RTM_DELETE relies on a previous RTM_GET to fill the buffer * appropriately. */ if (cmd == RTM_DELETE) goto doit; bzero((char *)&m_rtmsg, sizeof(m_rtmsg)); rtm->rtm_flags = flags; rtm->rtm_version = RTM_VERSION; switch (cmd) { default: xo_errx(1, "internal wrong cmd"); case RTM_ADD: rtm->rtm_addrs |= RTA_GATEWAY; rtm->rtm_rmx.rmx_expire = expire_time; rtm->rtm_inits = RTV_EXPIRE; rtm->rtm_flags |= (RTF_HOST | RTF_STATIC | RTF_LLDATA); /* FALLTHROUGH */ case RTM_GET: rtm->rtm_addrs |= RTA_DST; } #define NEXTADDR(w, s) \ do { \ if ((s) != NULL && rtm->rtm_addrs & (w)) { \ bcopy((s), cp, sizeof(*(s))); \ cp += SA_SIZE(s); \ } \ } while (0) NEXTADDR(RTA_DST, dst); NEXTADDR(RTA_GATEWAY, sdl); rtm->rtm_msglen = cp - (char *)&m_rtmsg; doit: l = rtm->rtm_msglen; rtm->rtm_seq = ++seq; rtm->rtm_type = cmd; if ((rlen = write(s, (char *)&m_rtmsg, l)) < 0) { if (errno != ESRCH || cmd != RTM_DELETE) { xo_warn("writing to routing socket"); return (NULL); } } do { l = read(s, (char *)&m_rtmsg, sizeof(m_rtmsg)); } while (l > 0 && (rtm->rtm_type != cmd || rtm->rtm_seq != seq || rtm->rtm_pid != pid)); if (l < 0) xo_warn("read from routing socket"); return (rtm); } /* * get_ether_addr - get the hardware address of an interface on the * the same subnet as ipaddr. */ #define MAX_IFS 32 static int get_ether_addr(in_addr_t ipaddr, struct ether_addr *hwaddr) { struct ifreq *ifr, *ifend, *ifp; in_addr_t ina, mask; struct sockaddr_dl *dla; struct ifreq ifreq; struct ifconf ifc; struct ifreq ifs[MAX_IFS]; int sock; int retval = 0; sock = socket(AF_INET, SOCK_DGRAM, 0); if (sock < 0) xo_err(1, "socket"); ifc.ifc_len = sizeof(ifs); ifc.ifc_req = ifs; if (ioctl(sock, SIOCGIFCONF, &ifc) < 0) { xo_warnx("ioctl(SIOCGIFCONF)"); goto done; } #define NEXTIFR(i) \ ((struct ifreq *)((char *)&(i)->ifr_addr \ + MAX((i)->ifr_addr.sa_len, sizeof((i)->ifr_addr))) ) /* * Scan through looking for an interface with an Internet * address on the same subnet as `ipaddr'. */ ifend = (struct ifreq *)(ifc.ifc_buf + ifc.ifc_len); for (ifr = ifc.ifc_req; ifr < ifend; ifr = NEXTIFR(ifr) ) { if (ifr->ifr_addr.sa_family != AF_INET) continue; strncpy(ifreq.ifr_name, ifr->ifr_name, sizeof(ifreq.ifr_name)); ifreq.ifr_addr = ifr->ifr_addr; /* * Check that the interface is up, * and not point-to-point or loopback. */ if (ioctl(sock, SIOCGIFFLAGS, &ifreq) < 0) continue; if ((ifreq.ifr_flags & (IFF_UP|IFF_BROADCAST|IFF_POINTOPOINT| IFF_LOOPBACK|IFF_NOARP)) != (IFF_UP|IFF_BROADCAST)) continue; /* Get its netmask and check that it's on the right subnet. */ if (ioctl(sock, SIOCGIFNETMASK, &ifreq) < 0) continue; mask = ((struct sockaddr_in *) &ifreq.ifr_addr)->sin_addr.s_addr; ina = ((struct sockaddr_in *) &ifr->ifr_addr)->sin_addr.s_addr; if ((ipaddr & mask) == (ina & mask)) break; /* ok, we got it! */ } if (ifr >= ifend) goto done; /* * Now scan through again looking for a link-level address * for this interface. */ ifp = ifr; for (ifr = ifc.ifc_req; ifr < ifend; ifr = NEXTIFR(ifr)) if (strcmp(ifp->ifr_name, ifr->ifr_name) == 0 && ifr->ifr_addr.sa_family == AF_LINK) break; if (ifr >= ifend) goto done; /* * Found the link-level address - copy it out */ dla = (struct sockaddr_dl *) &ifr->ifr_addr; memcpy(hwaddr, LLADDR(dla), dla->sdl_alen); printf("using interface %s for proxy with address %s\n", ifp->ifr_name, ether_ntoa(hwaddr)); retval = dla->sdl_alen; done: close(sock); return (retval); }
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