/* * Copyright (c) 1990, 1991, 1992, 1993, 1996 * The Regents of the University of California. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that: (1) source code distributions * retain the above copyright notice and this paragraph in its entirety, (2) * distributions including binary code include the above copyright notice and * this paragraph in its entirety in the documentation or other materials * provided with the distribution, and (3) all advertising materials mentioning * features or use of this software display the following acknowledgement: * ``This product includes software developed by the University of California, * Lawrence Berkeley Laboratory and its contributors.'' 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 ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. */ #ifndef lint static const char copyright[] = "@(#) Copyright (c) 1990, 1991, 1992, 1993, 1996\n\ The Regents of the University of California. All rights reserved.\n"; #endif /* not lint */ #ifndef lint static const char rcsid[] = "$FreeBSD$"; #endif /* not lint */ /* * rarpd - Reverse ARP Daemon * * Usage: rarpd -a [ -fsv ] [ hostname ] * rarpd [ -fsv ] interface [ hostname ] * * 'hostname' is optional solely for backwards compatibility with Sun's rarpd. * Currently, the argument is ignored. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #if defined(SUNOS4) || defined(__FreeBSD__) /* XXX */ #define HAVE_DIRENT_H #endif #ifdef HAVE_DIRENT_H #include #else #include #endif /* Cast a struct sockaddr to a structaddr_in */ #define SATOSIN(sa) ((struct sockaddr_in *)(sa)) #ifndef TFTP_DIR #define TFTP_DIR "/tftpboot" #endif #if BSD >= 199200 #define ARPSECS (20 * 60) /* as per code in netinet/if_ether.c */ #define REVARP_REQUEST ARPOP_REVREQUEST #define REVARP_REPLY ARPOP_REVREPLY #endif #ifndef ETHERTYPE_REVARP #define ETHERTYPE_REVARP 0x8035 #define REVARP_REQUEST 3 #define REVARP_REPLY 4 #endif /* * Map field names in ether_arp struct. What a pain in the neck. */ #ifdef SUNOS3 #undef arp_sha #undef arp_spa #undef arp_tha #undef arp_tpa #define arp_sha arp_xsha #define arp_spa arp_xspa #define arp_tha arp_xtha #define arp_tpa arp_xtpa #endif #ifndef __GNUC__ #define inline #endif /* * The structure for each interface. */ struct if_info { struct if_info *ii_next; int ii_fd; /* BPF file descriptor */ u_long ii_ipaddr; /* IP address of this interface */ u_long ii_netmask; /* subnet or net mask */ u_char ii_eaddr[6]; /* Ethernet address of this interface */ char ii_ifname[sizeof(((struct ifreq *)0)->ifr_name) + 1]; }; /* * The list of all interfaces that are being listened to. rarp_loop() * "selects" on the descriptors in this list. */ struct if_info *iflist; int verbose; /* verbose messages */ int s; /* inet datagram socket */ char *tftp_dir = TFTP_DIR; /* tftp directory */ #ifndef __P #define __P(protos) () #endif #if BSD < 199200 extern char *malloc(); extern void exit(); #endif extern int ether_ntohost(); void init __P((char *)); void init_one __P((struct ifreq *, char *)); char *intoa __P((u_long)); u_long ipaddrtonetmask __P((u_long)); char *eatoa __P((u_char *)); int rarp_bootable __P((u_long)); void rarp_loop __P((void)); int rarp_open __P((char *)); void rarp_process __P((struct if_info *, u_char *, u_int)); void rarp_reply __P((struct if_info *, struct ether_header *, u_long, u_int)); void update_arptab __P((u_char *, u_long)); static void usage __P((void)); static u_char zero[6]; int sflag = 0; /* ignore /tftpboot */ int main(argc, argv) int argc; char **argv; { int op; char *ifname, *hostname, *name; int aflag = 0; /* listen on "all" interfaces */ int fflag = 0; /* don't fork */ if ((name = strrchr(argv[0], '/')) != NULL) ++name; else name = argv[0]; if (*name == '-') ++name; /* * All error reporting is done through syslogs. */ openlog(name, LOG_PID | LOG_CONS, LOG_DAEMON); opterr = 0; while ((op = getopt(argc, argv, "afsv")) != -1) { switch (op) { case 'a': ++aflag; break; case 'f': ++fflag; break; case 's': ++sflag; break; case 'v': ++verbose; break; default: usage(); /* NOTREACHED */ } } ifname = argv[optind++]; hostname = ifname ? argv[optind] : NULL; if ((aflag && ifname) || (!aflag && ifname == NULL)) usage(); if (aflag) init(NULL); else init(ifname); if (!fflag) { if (daemon(0,0)) { syslog(LOG_ERR, "cannot fork"); exit(1); } } rarp_loop(); return(0); } /* * Add to the interface list. */ void init_one(ifrp, target) register struct ifreq *ifrp; register char *target; { register struct if_info *ii; register struct sockaddr_dl *ll; int family; struct ifreq ifr; family = ifrp->ifr_addr.sa_family; switch (family) { case AF_INET: #if BSD >= 199100 case AF_LINK: #endif (void)strncpy(ifr.ifr_name, ifrp->ifr_name, sizeof(ifrp->ifr_name)); if (ioctl(s, SIOCGIFFLAGS, (char *)&ifr) < 0) { syslog(LOG_ERR, "SIOCGIFFLAGS: %.*s: %m", sizeof(ifrp->ifr_name), ifrp->ifr_name); exit(1); } if ((ifr.ifr_flags & IFF_UP) == 0 || (ifr.ifr_flags & (IFF_LOOPBACK | IFF_POINTOPOINT)) != 0) return; break; default: return; } /* Don't bother going any further if not the target interface */ if (target != NULL && strncmp(ifrp->ifr_name, target, sizeof(ifrp->ifr_name)) != 0) return; /* Look for interface in list */ for (ii = iflist; ii != NULL; ii = ii->ii_next) if (strncmp(ifrp->ifr_name, ii->ii_ifname, sizeof(ifrp->ifr_name)) == 0) break; /* Allocate a new one if not found */ if (ii == NULL) { ii = (struct if_info *)malloc(sizeof(*ii)); if (ii == NULL) { syslog(LOG_ERR, "malloc: %m"); exit(1); } bzero(ii, sizeof(*ii)); ii->ii_fd = -1; (void)strncpy(ii->ii_ifname, ifrp->ifr_name, sizeof(ifrp->ifr_name)); ii->ii_ifname[sizeof(ii->ii_ifname) - 1] = '\0'; ii->ii_next = iflist; iflist = ii; } switch (family) { case AF_INET: if (ioctl(s, SIOCGIFADDR, (char *)&ifr) < 0) { syslog(LOG_ERR, "ipaddr SIOCGIFADDR: %s: %m", ii->ii_ifname); exit(1); } ii->ii_ipaddr = SATOSIN(&ifr.ifr_addr)->sin_addr.s_addr; if (ioctl(s, SIOCGIFNETMASK, (char *)&ifr) < 0) { syslog(LOG_ERR, "SIOCGIFNETMASK: %m"); exit(1); } ii->ii_netmask = SATOSIN(&ifr.ifr_addr)->sin_addr.s_addr; if (ii->ii_netmask == 0) ii->ii_netmask = ipaddrtonetmask(ii->ii_ipaddr); if (ii->ii_fd < 0) { ii->ii_fd = rarp_open(ii->ii_ifname); #if BSD < 199100 /* Use BPF descriptor to get ethernet address. */ if (ioctl(ii->ii_fd, SIOCGIFADDR, (char *)&ifr) < 0) { syslog(LOG_ERR, "eaddr SIOCGIFADDR: %s: %m", ii->ii_ifname); exit(1); } bcopy(&ifr.ifr_addr.sa_data[0], ii->ii_eaddr, 6); #endif } break; #if BSD >= 199100 case AF_LINK: ll = (struct sockaddr_dl *)&ifrp->ifr_addr; if (ll->sdl_type == IFT_ETHER) bcopy(LLADDR(ll), ii->ii_eaddr, 6); break; #endif } } /* * Initialize all "candidate" interfaces that are in the system * configuration list. A "candidate" is up, not loopback and not * point to point. */ void init(target) char *target; { register int n; register struct ifreq *ifrp, *ifend; register struct if_info *ii, *nii, *lii; struct ifconf ifc; struct ifreq ibuf[16]; if ((s = socket(AF_INET, SOCK_DGRAM, 0)) < 0) { syslog(LOG_ERR, "socket: %m"); exit(1); } ifc.ifc_len = sizeof ibuf; ifc.ifc_buf = (caddr_t)ibuf; if (ioctl(s, SIOCGIFCONF, (char *)&ifc) < 0 || (u_int)ifc.ifc_len < sizeof(struct ifreq)) { syslog(LOG_ERR, "SIOCGIFCONF: %m"); exit(1); } ifrp = ibuf; ifend = (struct ifreq *)((char *)ibuf + ifc.ifc_len); while (ifrp < ifend) { init_one(ifrp, target); #if BSD >= 199100 n = ifrp->ifr_addr.sa_len + sizeof(ifrp->ifr_name); if (n < sizeof(*ifrp)) n = sizeof(*ifrp); ifrp = (struct ifreq *)((char *)ifrp + n); #else ++ifrp; #endif } /* Throw away incomplete interfaces */ lii = NULL; for (ii = iflist; ii != NULL; ii = nii) { nii = ii->ii_next; if (ii->ii_ipaddr == 0 || bcmp(ii->ii_eaddr, zero, 6) == 0) { if (lii == NULL) iflist = nii; else lii->ii_next = nii; if (ii->ii_fd >= 0) close(ii->ii_fd); free(ii); continue; } lii = ii; } /* Verbose stuff */ if (verbose) for (ii = iflist; ii != NULL; ii = ii->ii_next) syslog(LOG_DEBUG, "%s %s 0x%08x %s", ii->ii_ifname, intoa(ntohl(ii->ii_ipaddr)), ntohl(ii->ii_netmask), eatoa(ii->ii_eaddr)); } static void usage() { (void)fprintf(stderr, "usage: rarpd [-afsv] [interface]\n"); exit(1); } static int bpf_open() { int fd; int n = 0; char device[sizeof "/dev/bpf000"]; /* * Go through all the minors and find one that isn't in use. */ do { (void)sprintf(device, "/dev/bpf%d", n++); fd = open(device, O_RDWR); } while (fd < 0 && errno == EBUSY); if (fd < 0) { syslog(LOG_ERR, "%s: %m", device); exit(1); } return fd; } /* * Open a BPF file and attach it to the interface named 'device'. * Set immediate mode, and set a filter that accepts only RARP requests. */ int rarp_open(device) char *device; { int fd; struct ifreq ifr; u_int dlt; int immediate; static struct bpf_insn insns[] = { BPF_STMT(BPF_LD|BPF_H|BPF_ABS, 12), BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, ETHERTYPE_REVARP, 0, 3), BPF_STMT(BPF_LD|BPF_H|BPF_ABS, 20), BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, REVARP_REQUEST, 0, 1), BPF_STMT(BPF_RET|BPF_K, sizeof(struct ether_arp) + sizeof(struct ether_header)), BPF_STMT(BPF_RET|BPF_K, 0), }; static struct bpf_program filter = { sizeof insns / sizeof(insns[0]), insns }; fd = bpf_open(); /* * Set immediate mode so packets are processed as they arrive. */ immediate = 1; if (ioctl(fd, BIOCIMMEDIATE, &immediate) < 0) { syslog(LOG_ERR, "BIOCIMMEDIATE: %m"); exit(1); } (void)strncpy(ifr.ifr_name, device, sizeof ifr.ifr_name); if (ioctl(fd, BIOCSETIF, (caddr_t)&ifr) < 0) { syslog(LOG_ERR, "BIOCSETIF: %m"); exit(1); } /* * Check that the data link layer is an Ethernet; this code won't * work with anything else. */ if (ioctl(fd, BIOCGDLT, (caddr_t)&dlt) < 0) { syslog(LOG_ERR, "BIOCGDLT: %m"); exit(1); } if (dlt != DLT_EN10MB) { syslog(LOG_ERR, "%s is not an ethernet", device); exit(1); } /* * Set filter program. */ if (ioctl(fd, BIOCSETF, (caddr_t)&filter) < 0) { syslog(LOG_ERR, "BIOCSETF: %m"); exit(1); } return fd; } /* * Perform various sanity checks on the RARP request packet. Return * false on failure and log the reason. */ static int rarp_check(p, len) u_char *p; u_int len; { struct ether_header *ep = (struct ether_header *)p; struct ether_arp *ap = (struct ether_arp *)(p + sizeof(*ep)); if (len < sizeof(*ep) + sizeof(*ap)) { syslog(LOG_ERR, "truncated request, got %d, expected %d", len, sizeof(*ep) + sizeof(*ap)); return 0; } /* * XXX This test might be better off broken out... */ if (ntohs(ep->ether_type) != ETHERTYPE_REVARP || ntohs(ap->arp_hrd) != ARPHRD_ETHER || ntohs(ap->arp_op) != REVARP_REQUEST || ntohs(ap->arp_pro) != ETHERTYPE_IP || ap->arp_hln != 6 || ap->arp_pln != 4) { syslog(LOG_DEBUG, "request fails sanity check"); return 0; } if (bcmp((char *)&ep->ether_shost, (char *)&ap->arp_sha, 6) != 0) { syslog(LOG_DEBUG, "ether/arp sender address mismatch"); return 0; } if (bcmp((char *)&ap->arp_sha, (char *)&ap->arp_tha, 6) != 0) { syslog(LOG_DEBUG, "ether/arp target address mismatch"); return 0; } return 1; } #ifndef FD_SETSIZE #define FD_SET(n, fdp) ((fdp)->fds_bits[0] |= (1 << (n))) #define FD_ISSET(n, fdp) ((fdp)->fds_bits[0] & (1 << (n))) #define FD_ZERO(fdp) ((fdp)->fds_bits[0] = 0) #endif /* * Loop indefinitely listening for RARP requests on the * interfaces in 'iflist'. */ void rarp_loop() { u_char *buf, *bp, *ep; int cc, fd; fd_set fds, listeners; int bufsize, maxfd = 0; struct if_info *ii; if (iflist == NULL) { syslog(LOG_ERR, "no interfaces"); exit(1); } if (ioctl(iflist->ii_fd, BIOCGBLEN, (caddr_t)&bufsize) < 0) { syslog(LOG_ERR, "BIOCGBLEN: %m"); exit(1); } buf = (u_char *)malloc((unsigned)bufsize); if (buf == NULL) { syslog(LOG_ERR, "malloc: %m"); exit(1); } while (1) { /* * Find the highest numbered file descriptor for select(). * Initialize the set of descriptors to listen to. */ FD_ZERO(&fds); for (ii = iflist; ii != NULL; ii = ii->ii_next) { FD_SET(ii->ii_fd, &fds); if (ii->ii_fd > maxfd) maxfd = ii->ii_fd; } listeners = fds; if (select(maxfd + 1, &listeners, NULL, NULL, NULL) < 0) { /* Don't choke when we get ptraced */ if (errno == EINTR) continue; syslog(LOG_ERR, "select: %m"); exit(1); } for (ii = iflist; ii != NULL; ii = ii->ii_next) { fd = ii->ii_fd; if (!FD_ISSET(fd, &listeners)) continue; again: cc = read(fd, (char *)buf, bufsize); /* Don't choke when we get ptraced */ if (cc < 0 && errno == EINTR) goto again; #if defined(SUNOS3) || defined(SUNOS4) /* * Due to a SunOS bug, after 2^31 bytes, the * file offset overflows and read fails with * EINVAL. The lseek() to 0 will fix things. */ if (cc < 0) { if (errno == EINVAL && (long)(tell(fd) + bufsize) < 0) { (void)lseek(fd, 0, 0); goto again; } syslog(LOG_ERR, "read: %m"); exit(1); } #endif /* Loop through the packet(s) */ #define bhp ((struct bpf_hdr *)bp) bp = buf; ep = bp + cc; while (bp < ep) { register u_int caplen, hdrlen; caplen = bhp->bh_caplen; hdrlen = bhp->bh_hdrlen; if (rarp_check(bp + hdrlen, caplen)) rarp_process(ii, bp + hdrlen, caplen); bp += BPF_WORDALIGN(hdrlen + caplen); } } } #undef bhp } /* * True if this server can boot the host whose IP address is 'addr'. * This check is made by looking in the tftp directory for the * configuration file. */ int rarp_bootable(addr) u_long addr; { #ifdef HAVE_DIRENT_H register struct dirent *dent; #else register struct direct *dent; #endif register DIR *d; char ipname[9]; static DIR *dd = NULL; (void)sprintf(ipname, "%08X", (unsigned int )ntohl(addr)); /* * If directory is already open, rewind it. Otherwise, open it. */ if ((d = dd) != NULL) rewinddir(d); else { if (chdir(tftp_dir) == -1) { syslog(LOG_ERR, "chdir: %s: %m", tftp_dir); exit(1); } d = opendir("."); if (d == NULL) { syslog(LOG_ERR, "opendir: %m"); exit(1); } dd = d; } while ((dent = readdir(d)) != NULL) if (strncmp(dent->d_name, ipname, 8) == 0) return 1; return 0; } /* * Given a list of IP addresses, 'alist', return the first address that * is on network 'net'; 'netmask' is a mask indicating the network portion * of the address. */ u_long choose_ipaddr(alist, net, netmask) u_long **alist; u_long net; u_long netmask; { for (; *alist; ++alist) if ((**alist & netmask) == net) return **alist; return 0; } /* * Answer the RARP request in 'pkt', on the interface 'ii'. 'pkt' has * already been checked for validity. The reply is overlaid on the request. */ void rarp_process(ii, pkt, len) struct if_info *ii; u_char *pkt; u_int len; { struct ether_header *ep; struct hostent *hp; u_long target_ipaddr; char ename[256]; ep = (struct ether_header *)pkt; /* should this be arp_tha? */ if (ether_ntohost(ename, &ep->ether_shost) != 0) { syslog(LOG_ERR, "cannot map %s to name", eatoa(ep->ether_shost)); return; } if ((hp = gethostbyname(ename)) == NULL) { syslog(LOG_ERR, "cannot map %s to IP address", ename); return; } /* * Choose correct address from list. */ if (hp->h_addrtype != AF_INET) { syslog(LOG_ERR, "cannot handle non IP addresses for %s", ename); return; } target_ipaddr = choose_ipaddr((u_long **)hp->h_addr_list, ii->ii_ipaddr & ii->ii_netmask, ii->ii_netmask); if (target_ipaddr == 0) { syslog(LOG_ERR, "cannot find %s on net %s", ename, intoa(ntohl(ii->ii_ipaddr & ii->ii_netmask))); return; } if (sflag || rarp_bootable(target_ipaddr)) rarp_reply(ii, ep, target_ipaddr, len); else if (verbose > 1) syslog(LOG_INFO, "%s %s at %s DENIED (not bootable)", ii->ii_ifname, eatoa(ep->ether_shost), intoa(ntohl(target_ipaddr))); } /* * Poke the kernel arp tables with the ethernet/ip address combinataion * given. When processing a reply, we must do this so that the booting * host (i.e. the guy running rarpd), won't try to ARP for the hardware * address of the guy being booted (he cannot answer the ARP). */ #if BSD >= 199200 static struct sockaddr_inarp sin_inarp = { sizeof(struct sockaddr_inarp), AF_INET }; static struct sockaddr_dl sin_dl = { sizeof(struct sockaddr_dl), AF_LINK, 0, IFT_ETHER, 0, 6 }; static struct { struct rt_msghdr rthdr; char rtspace[512]; } rtmsg; void update_arptab(ep, ipaddr) u_char *ep; u_long ipaddr; { register int cc; register struct sockaddr_inarp *ar, *ar2; register struct sockaddr_dl *ll, *ll2; register struct rt_msghdr *rt; register int xtype, xindex; static pid_t pid; int r; static seq; r = socket(PF_ROUTE, SOCK_RAW, 0); if (r < 0) { syslog(LOG_ERR, "raw route socket: %m"); exit(1); } pid = getpid(); ar = &sin_inarp; ar->sin_addr.s_addr = ipaddr; ll = &sin_dl; bcopy(ep, LLADDR(ll), 6); /* Get the type and interface index */ rt = &rtmsg.rthdr; bzero(rt, sizeof(rtmsg)); rt->rtm_version = RTM_VERSION; rt->rtm_addrs = RTA_DST; rt->rtm_type = RTM_GET; rt->rtm_seq = ++seq; ar2 = (struct sockaddr_inarp *)rtmsg.rtspace; bcopy(ar, ar2, sizeof(*ar)); rt->rtm_msglen = sizeof(*rt) + sizeof(*ar); errno = 0; if (write(r, rt, rt->rtm_msglen) < 0 && errno != ESRCH) { syslog(LOG_ERR, "rtmsg get write: %m"); close(r); return; } do { cc = read(r, rt, sizeof(rtmsg)); } while (cc > 0 && (rt->rtm_seq != seq || rt->rtm_pid != pid)); if (cc < 0) { syslog(LOG_ERR, "rtmsg get read: %m"); close(r); return; } ll2 = (struct sockaddr_dl *)((u_char *)ar2 + ar2->sin_len); if (ll2->sdl_family != AF_LINK) { /* * XXX I think this means the ip address is not on a * directly connected network (the family is AF_INET in * this case). */ syslog(LOG_ERR, "bogus link family (%d) wrong net for %08X?\n", ll2->sdl_family, ipaddr); close(r); return; } xtype = ll2->sdl_type; xindex = ll2->sdl_index; /* Set the new arp entry */ bzero(rt, sizeof(rtmsg)); rt->rtm_version = RTM_VERSION; rt->rtm_addrs = RTA_DST | RTA_GATEWAY; rt->rtm_inits = RTV_EXPIRE; rt->rtm_rmx.rmx_expire = time(0) + ARPSECS; rt->rtm_flags = RTF_HOST | RTF_STATIC; rt->rtm_type = RTM_ADD; rt->rtm_seq = ++seq; bcopy(ar, ar2, sizeof(*ar)); ll2 = (struct sockaddr_dl *)((u_char *)ar2 + sizeof(*ar2)); bcopy(ll, ll2, sizeof(*ll)); ll2->sdl_type = xtype; ll2->sdl_index = xindex; rt->rtm_msglen = sizeof(*rt) + sizeof(*ar2) + sizeof(*ll2); errno = 0; if (write(r, rt, rt->rtm_msglen) < 0 && errno != EEXIST) { syslog(LOG_ERR, "rtmsg add write: %m"); close(r); return; } do { cc = read(r, rt, sizeof(rtmsg)); } while (cc > 0 && (rt->rtm_seq != seq || rt->rtm_pid != pid)); close(r); if (cc < 0) { syslog(LOG_ERR, "rtmsg add read: %m"); return; } } #else void update_arptab(ep, ipaddr) u_char *ep; u_long ipaddr; { struct arpreq request; struct sockaddr_in *sin; request.arp_flags = 0; sin = (struct sockaddr_in *)&request.arp_pa; sin->sin_family = AF_INET; sin->sin_addr.s_addr = ipaddr; request.arp_ha.sa_family = AF_UNSPEC; bcopy((char *)ep, (char *)request.arp_ha.sa_data, 6); if (ioctl(s, SIOCSARP, (caddr_t)&request) < 0) syslog(LOG_ERR, "SIOCSARP: %m"); } #endif /* * Build a reverse ARP packet and sent it out on the interface. * 'ep' points to a valid REVARP_REQUEST. The REVARP_REPLY is built * on top of the request, then written to the network. * * RFC 903 defines the ether_arp fields as follows. The following comments * are taken (more or less) straight from this document. * * REVARP_REQUEST * * arp_sha is the hardware address of the sender of the packet. * arp_spa is undefined. * arp_tha is the 'target' hardware address. * In the case where the sender wishes to determine his own * protocol address, this, like arp_sha, will be the hardware * address of the sender. * arp_tpa is undefined. * * REVARP_REPLY * * arp_sha is the hardware address of the responder (the sender of the * reply packet). * arp_spa is the protocol address of the responder (see the note below). * arp_tha is the hardware address of the target, and should be the same as * that which was given in the request. * arp_tpa is the protocol address of the target, that is, the desired address. * * Note that the requirement that arp_spa be filled in with the responder's * protocol is purely for convenience. For instance, if a system were to use * both ARP and RARP, then the inclusion of the valid protocol-hardware * address pair (arp_spa, arp_sha) may eliminate the need for a subsequent * ARP request. */ void rarp_reply(ii, ep, ipaddr, len) struct if_info *ii; struct ether_header *ep; u_long ipaddr; u_int len; { int n; struct ether_arp *ap = (struct ether_arp *)(ep + 1); update_arptab((u_char *)&ap->arp_sha, ipaddr); /* * Build the rarp reply by modifying the rarp request in place. */ ap->arp_op = htons(REVARP_REPLY); #ifdef BROKEN_BPF ep->ether_type = ETHERTYPE_REVARP; #endif bcopy((char *)&ap->arp_sha, (char *)&ep->ether_dhost, 6); bcopy((char *)ii->ii_eaddr, (char *)&ep->ether_shost, 6); bcopy((char *)ii->ii_eaddr, (char *)&ap->arp_sha, 6); bcopy((char *)&ipaddr, (char *)ap->arp_tpa, 4); /* Target hardware is unchanged. */ bcopy((char *)&ii->ii_ipaddr, (char *)ap->arp_spa, 4); /* Zero possible garbage after packet. */ bzero((char *)ep + (sizeof(*ep) + sizeof(*ap)), len - (sizeof(*ep) + sizeof(*ap))); n = write(ii->ii_fd, (char *)ep, len); if (n != len) syslog(LOG_ERR, "write: only %d of %d bytes written", n, len); if (verbose) syslog(LOG_INFO, "%s %s at %s REPLIED", ii->ii_ifname, eatoa(ap->arp_tha), intoa(ntohl(ipaddr))); } /* * Get the netmask of an IP address. This routine is used if * SIOCGIFNETMASK doesn't work. */ u_long ipaddrtonetmask(addr) u_long addr; { addr = ntohl(addr); if (IN_CLASSA(addr)) return htonl(IN_CLASSA_NET); if (IN_CLASSB(addr)) return htonl(IN_CLASSB_NET); if (IN_CLASSC(addr)) return htonl(IN_CLASSC_NET); syslog(LOG_DEBUG, "unknown IP address class: %08X", addr); return htonl(0xffffffff); } /* * A faster replacement for inet_ntoa(). */ char * intoa(addr) u_long addr; { register char *cp; register u_int byte; register int n; static char buf[sizeof(".xxx.xxx.xxx.xxx")]; cp = &buf[sizeof buf]; *--cp = '\0'; n = 4; do { byte = addr & 0xff; *--cp = byte % 10 + '0'; byte /= 10; if (byte > 0) { *--cp = byte % 10 + '0'; byte /= 10; if (byte > 0) *--cp = byte + '0'; } *--cp = '.'; addr >>= 8; } while (--n > 0); return cp + 1; } char * eatoa(ea) register u_char *ea; { static char buf[sizeof("xx:xx:xx:xx:xx:xx")]; (void)sprintf(buf, "%x:%x:%x:%x:%x:%x", ea[0], ea[1], ea[2], ea[3], ea[4], ea[5]); return (buf); }