diff options
Diffstat (limited to 'usr.sbin/rarpd/rarpd.c')
| -rw-r--r-- | usr.sbin/rarpd/rarpd.c | 997 |
1 files changed, 997 insertions, 0 deletions
diff --git a/usr.sbin/rarpd/rarpd.c b/usr.sbin/rarpd/rarpd.c new file mode 100644 index 000000000000..6281fbfd0c6b --- /dev/null +++ b/usr.sbin/rarpd/rarpd.c @@ -0,0 +1,997 @@ +/*- + * SPDX-License-Identifier: BSD-1-Clause + * + * 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 + * + * 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. + */ + +/* + * rarpd - Reverse ARP Daemon + * + * Usage: rarpd -a [-dfsv] [-t directory] [-P pidfile] [hostname] + * rarpd [-dfsv] [-t directory] [-P pidfile] interface [hostname] + * + * 'hostname' is optional solely for backwards compatibility with Sun's rarpd. + * Currently, the argument is ignored. + */ +#include <sys/param.h> +#include <sys/file.h> +#include <sys/ioctl.h> +#include <sys/socket.h> +#include <sys/time.h> + +#include <net/bpf.h> +#include <net/ethernet.h> +#include <net/if.h> +#include <net/if_types.h> +#include <net/if_dl.h> +#include <net/route.h> + +#include <netinet/in.h> +#include <netinet/if_ether.h> + +#include <arpa/inet.h> + +#include <dirent.h> +#include <errno.h> +#include <ifaddrs.h> +#include <netdb.h> +#include <stdarg.h> +#include <stdio.h> +#include <string.h> +#include <syslog.h> +#include <stdlib.h> +#include <unistd.h> +#include <libutil.h> + +/* Cast a struct sockaddr to a struct sockaddr_in */ +#define SATOSIN(sa) ((struct sockaddr_in *)(sa)) + +#ifndef TFTP_DIR +#define TFTP_DIR "/tftpboot" +#endif + +#define ARPSECS (20 * 60) /* as per code in netinet/if_ether.c */ +#define REVARP_REQUEST ARPOP_REVREQUEST +#define REVARP_REPLY ARPOP_REVREPLY + +/* + * The structure for each interface. + */ +struct if_info { + struct if_info *ii_next; + int ii_fd; /* BPF file descriptor */ + in_addr_t ii_ipaddr; /* IP address */ + in_addr_t ii_netmask; /* subnet or net mask */ + u_char ii_eaddr[ETHER_ADDR_LEN]; /* ethernet address */ + char ii_ifname[IF_NAMESIZE]; +}; + +/* + * The list of all interfaces that are being listened to. rarp_loop() + * "selects" on the descriptors in this list. + */ +static struct if_info *iflist; + +static int verbose; /* verbose messages */ +static const char *tftp_dir = TFTP_DIR; /* tftp directory */ + +static int dflag; /* messages to stdout/stderr, not syslog(3) */ +static int sflag; /* ignore /tftpboot */ + +static u_char zero[6]; + +static char pidfile_buf[PATH_MAX]; +static char *pidfile; +#define RARPD_PIDFILE "/var/run/rarpd.%s.pid" +static struct pidfh *pidfile_fh; + +static int bpf_open(void); +static in_addr_t choose_ipaddr(in_addr_t **, in_addr_t, in_addr_t); +static char *eatoa(u_char *); +static int expand_syslog_m(const char *fmt, char **newfmt); +static void init(char *); +static void init_one(struct ifaddrs *, char *, int); +static char *intoa(in_addr_t); +static in_addr_t ipaddrtonetmask(in_addr_t); +static void logmsg(int, const char *, ...) __printflike(2, 3); +static int rarp_bootable(in_addr_t); +static int rarp_check(u_char *, u_int); +static void rarp_loop(void); +static int rarp_open(char *); +static void rarp_process(struct if_info *, u_char *, u_int); +static void rarp_reply(struct if_info *, struct ether_header *, + in_addr_t, u_int); +static void update_arptab(u_char *, in_addr_t); +static void usage(void); + +int +main(int argc, char *argv[]) +{ + int op; + char *ifname, *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 syslog, unless -d is specified + */ + openlog(name, LOG_PID | LOG_CONS, LOG_DAEMON); + + opterr = 0; + while ((op = getopt(argc, argv, "adfsP:t:v")) != -1) + switch (op) { + case 'a': + ++aflag; + break; + + case 'd': + ++dflag; + break; + + case 'f': + ++fflag; + break; + + case 's': + ++sflag; + break; + + case 'P': + strncpy(pidfile_buf, optarg, sizeof(pidfile_buf) - 1); + pidfile_buf[sizeof(pidfile_buf) - 1] = '\0'; + pidfile = pidfile_buf; + break; + + case 't': + tftp_dir = optarg; + break; + + case 'v': + ++verbose; + break; + + default: + usage(); + /* NOTREACHED */ + } + argc -= optind; + argv += optind; + + ifname = (aflag == 0) ? argv[0] : NULL; + + if ((aflag && ifname) || (!aflag && ifname == NULL)) + usage(); + + init(ifname); + + if (!fflag) { + if (pidfile == NULL && ifname != NULL && aflag == 0) { + snprintf(pidfile_buf, sizeof(pidfile_buf) - 1, + RARPD_PIDFILE, ifname); + pidfile_buf[sizeof(pidfile_buf) - 1] = '\0'; + pidfile = pidfile_buf; + } + /* If pidfile == NULL, /var/run/<progname>.pid will be used. */ + pidfile_fh = pidfile_open(pidfile, 0600, NULL); + if (pidfile_fh == NULL) + logmsg(LOG_ERR, "Cannot open or create pidfile: %s", + (pidfile == NULL) ? "/var/run/rarpd.pid" : pidfile); + if (daemon(0,0)) { + logmsg(LOG_ERR, "cannot fork"); + pidfile_remove(pidfile_fh); + exit(1); + } + pidfile_write(pidfile_fh); + } + rarp_loop(); + return(0); +} + +/* + * Add to the interface list. + */ +static void +init_one(struct ifaddrs *ifa, char *target, int pass1) +{ + struct if_info *ii, *ii2; + struct sockaddr_dl *ll; + int family; + + family = ifa->ifa_addr->sa_family; + switch (family) { + case AF_INET: + if (pass1) + /* Consider only AF_LINK during pass1. */ + return; + /* FALLTHROUGH */ + case AF_LINK: + if (!(ifa->ifa_flags & IFF_UP) || + (ifa->ifa_flags & (IFF_LOOPBACK | IFF_POINTOPOINT))) + return; + break; + default: + return; + } + + /* Don't bother going any further if not the target interface */ + if (target != NULL && strcmp(ifa->ifa_name, target) != 0) + return; + + /* Look for interface in list */ + for (ii = iflist; ii != NULL; ii = ii->ii_next) + if (strcmp(ifa->ifa_name, ii->ii_ifname) == 0) + break; + + if (pass1 && ii != NULL) + /* We've already seen that interface once. */ + return; + + /* Allocate a new one if not found */ + if (ii == NULL) { + ii = (struct if_info *)malloc(sizeof(*ii)); + if (ii == NULL) { + logmsg(LOG_ERR, "malloc: %m"); + pidfile_remove(pidfile_fh); + exit(1); + } + bzero(ii, sizeof(*ii)); + ii->ii_fd = -1; + strlcpy(ii->ii_ifname, ifa->ifa_name, sizeof(ii->ii_ifname)); + ii->ii_next = iflist; + iflist = ii; + } else if (!pass1 && ii->ii_ipaddr != 0) { + /* + * Second AF_INET definition for that interface: clone + * the existing one, and work on that cloned one. + * This must be another IP address for this interface, + * so avoid killing the previous configuration. + */ + ii2 = (struct if_info *)malloc(sizeof(*ii2)); + if (ii2 == NULL) { + logmsg(LOG_ERR, "malloc: %m"); + pidfile_remove(pidfile_fh); + exit(1); + } + memcpy(ii2, ii, sizeof(*ii2)); + ii2->ii_fd = -1; + ii2->ii_next = iflist; + iflist = ii2; + + ii = ii2; + } + + switch (family) { + case AF_INET: + ii->ii_ipaddr = SATOSIN(ifa->ifa_addr)->sin_addr.s_addr; + ii->ii_netmask = SATOSIN(ifa->ifa_netmask)->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); + break; + + case AF_LINK: + ll = (struct sockaddr_dl *)ifa->ifa_addr; + switch (ll->sdl_type) { + case IFT_ETHER: + case IFT_L2VLAN: + bcopy(LLADDR(ll), ii->ii_eaddr, 6); + } + break; + } +} + +/* + * Initialize all "candidate" interfaces that are in the system + * configuration list. A "candidate" is up, not loopback and not + * point to point. + */ +static void +init(char *target) +{ + struct if_info *ii, *nii, *lii; + struct ifaddrs *ifhead, *ifa; + int error; + + error = getifaddrs(&ifhead); + if (error) { + logmsg(LOG_ERR, "getifaddrs: %m"); + pidfile_remove(pidfile_fh); + exit(1); + } + /* + * We make two passes over the list we have got. In the first + * one, we only collect AF_LINK interfaces, and initialize our + * list of interfaces from them. In the second pass, we + * collect the actual IP addresses from the AF_INET + * interfaces, and allow for the same interface name to appear + * multiple times (in case of more than one IP address). + */ + for (ifa = ifhead; ifa != NULL; ifa = ifa->ifa_next) + init_one(ifa, target, 1); + for (ifa = ifhead; ifa != NULL; ifa = ifa->ifa_next) + init_one(ifa, target, 0); + freeifaddrs(ifhead); + + /* 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) + logmsg(LOG_DEBUG, "%s %s 0x%08x %s", + ii->ii_ifname, intoa(ntohl(ii->ii_ipaddr)), + (in_addr_t)ntohl(ii->ii_netmask), eatoa(ii->ii_eaddr)); +} + +static void +usage(void) +{ + + (void)fprintf(stderr, "%s\n%s\n", + "usage: rarpd -a [-dfsv] [-t directory] [-P pidfile]", + " rarpd [-dfsv] [-t directory] [-P pidfile] interface"); + exit(1); +} + +static int +bpf_open(void) +{ + 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 == -1) && (errno == EBUSY)); + + if (fd == -1) { + logmsg(LOG_ERR, "%s: %m", device); + pidfile_remove(pidfile_fh); + 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. + */ +static int +rarp_open(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) == -1) { + logmsg(LOG_ERR, "BIOCIMMEDIATE: %m"); + goto rarp_open_err; + } + strlcpy(ifr.ifr_name, device, sizeof(ifr.ifr_name)); + if (ioctl(fd, BIOCSETIF, (caddr_t)&ifr) == -1) { + logmsg(LOG_ERR, "BIOCSETIF: %m"); + goto rarp_open_err; + } + /* + * Check that the data link layer is an Ethernet; this code won't + * work with anything else. + */ + if (ioctl(fd, BIOCGDLT, (caddr_t)&dlt) == -1) { + logmsg(LOG_ERR, "BIOCGDLT: %m"); + goto rarp_open_err; + } + if (dlt != DLT_EN10MB) { + logmsg(LOG_ERR, "%s is not an ethernet", device); + goto rarp_open_err; + } + /* + * Set filter program. + */ + if (ioctl(fd, BIOCSETF, (caddr_t)&filter) == -1) { + logmsg(LOG_ERR, "BIOCSETF: %m"); + goto rarp_open_err; + } + return fd; + +rarp_open_err: + pidfile_remove(pidfile_fh); + exit(1); +} + +/* + * Perform various sanity checks on the RARP request packet. Return + * false on failure and log the reason. + */ +static int +rarp_check(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)) { + logmsg(LOG_ERR, "truncated request, got %u, expected %lu", + len, (u_long)(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) { + logmsg(LOG_DEBUG, "request fails sanity check"); + return 0; + } + if (bcmp((char *)&ep->ether_shost, (char *)&ap->arp_sha, 6) != 0) { + logmsg(LOG_DEBUG, "ether/arp sender address mismatch"); + return 0; + } + if (bcmp((char *)&ap->arp_sha, (char *)&ap->arp_tha, 6) != 0) { + logmsg(LOG_DEBUG, "ether/arp target address mismatch"); + return 0; + } + return 1; +} + +/* + * Loop indefinitely listening for RARP requests on the + * interfaces in 'iflist'. + */ +static void +rarp_loop(void) +{ + u_char *buf, *bp, *ep; + int cc, fd; + fd_set fds, listeners; + int bufsize, maxfd = 0; + struct if_info *ii; + + if (iflist == NULL) { + logmsg(LOG_ERR, "no interfaces"); + goto rarpd_loop_err; + } + if (ioctl(iflist->ii_fd, BIOCGBLEN, (caddr_t)&bufsize) == -1) { + logmsg(LOG_ERR, "BIOCGBLEN: %m"); + goto rarpd_loop_err; + } + buf = malloc(bufsize); + if (buf == NULL) { + logmsg(LOG_ERR, "malloc: %m"); + goto rarpd_loop_err; + } + + 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) == -1) { + /* Don't choke when we get ptraced */ + if (errno == EINTR) + continue; + logmsg(LOG_ERR, "select: %m"); + goto rarpd_loop_err; + } + 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 == -1) && (errno == EINTR)) + goto again; + + /* Loop through the packet(s) */ +#define bhp ((struct bpf_hdr *)bp) + bp = buf; + ep = bp + cc; + while (bp < ep) { + 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 + return; + +rarpd_loop_err: + pidfile_remove(pidfile_fh); + exit(1); +} + +/* + * 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. + */ +static int +rarp_bootable(in_addr_t addr) +{ + struct dirent *dent; + DIR *d; + char ipname[9]; + static DIR *dd = NULL; + + (void)sprintf(ipname, "%08X", (in_addr_t)ntohl(addr)); + + /* + * If directory is already open, rewind it. Otherwise, open it. + */ + if ((d = dd) != NULL) + rewinddir(d); + else { + if (chdir(tftp_dir) == -1) { + logmsg(LOG_ERR, "chdir: %s: %m", tftp_dir); + goto rarp_bootable_err; + } + d = opendir("."); + if (d == NULL) { + logmsg(LOG_ERR, "opendir: %m"); + goto rarp_bootable_err; + } + dd = d; + } + while ((dent = readdir(d)) != NULL) + if (strncmp(dent->d_name, ipname, 8) == 0) + return 1; + return 0; + +rarp_bootable_err: + pidfile_remove(pidfile_fh); + exit(1); +} + +/* + * 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. + */ +static in_addr_t +choose_ipaddr(in_addr_t **alist, in_addr_t net, in_addr_t 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. + */ +static void +rarp_process(struct if_info *ii, u_char *pkt, u_int len) +{ + struct ether_header *ep; + struct hostent *hp; + in_addr_t target_ipaddr; + char ename[256]; + + ep = (struct ether_header *)pkt; + /* should this be arp_tha? */ + if (ether_ntohost(ename, (struct ether_addr *)&ep->ether_shost) != 0) { + logmsg(LOG_ERR, "cannot map %s to name", + eatoa(ep->ether_shost)); + return; + } + + if ((hp = gethostbyname(ename)) == NULL) { + logmsg(LOG_ERR, "cannot map %s to IP address", ename); + return; + } + + /* + * Choose correct address from list. + */ + if (hp->h_addrtype != AF_INET) { + logmsg(LOG_ERR, "cannot handle non IP addresses for %s", + ename); + return; + } + target_ipaddr = choose_ipaddr((in_addr_t **)hp->h_addr_list, + ii->ii_ipaddr & ii->ii_netmask, + ii->ii_netmask); + if (target_ipaddr == 0) { + logmsg(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) + logmsg(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 combination + * 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). + */ +static struct sockaddr_in sin_inarp = { + sizeof(struct sockaddr_in), AF_INET, 0, + {0}, + {0}, +}; + +static struct sockaddr_dl sin_dl = { + sizeof(struct sockaddr_dl), AF_LINK, 0, IFT_ETHER, 0, 6, + 0, "" +}; + +static struct { + struct rt_msghdr rthdr; + char rtspace[512]; +} rtmsg; + +static void +update_arptab(u_char *ep, in_addr_t ipaddr) +{ + struct timespec tp; + int cc; + struct sockaddr_in *ar, *ar2; + struct sockaddr_dl *ll, *ll2; + struct rt_msghdr *rt; + int xtype, xindex; + static pid_t pid; + int r; + static int seq; + + r = socket(PF_ROUTE, SOCK_RAW, 0); + if (r == -1) { + logmsg(LOG_ERR, "raw route socket: %m"); + pidfile_remove(pidfile_fh); + 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(&rtmsg, sizeof(rtmsg)); + rt->rtm_version = RTM_VERSION; + rt->rtm_addrs = RTA_DST; + rt->rtm_type = RTM_GET; + rt->rtm_seq = ++seq; + ar2 = (struct sockaddr_in *)rtmsg.rtspace; + bcopy(ar, ar2, sizeof(*ar)); + rt->rtm_msglen = sizeof(*rt) + sizeof(*ar); + errno = 0; + if ((write(r, rt, rt->rtm_msglen) == -1) && (errno != ESRCH)) { + logmsg(LOG_ERR, "rtmsg get write: %m"); + close(r); + return; + } + do { + cc = read(r, rt, sizeof(rtmsg)); + } while (cc > 0 && (rt->rtm_type != RTM_GET || rt->rtm_seq != seq || + rt->rtm_pid != pid)); + if (cc == -1) { + logmsg(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). + */ + logmsg(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; + clock_gettime(CLOCK_MONOTONIC, &tp); + rt->rtm_rmx.rmx_expire = tp.tv_sec + 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) == -1) && (errno != EEXIST)) { + logmsg(LOG_ERR, "rtmsg add write: %m"); + close(r); + return; + } + do { + cc = read(r, rt, sizeof(rtmsg)); + } while (cc > 0 && (rt->rtm_type != RTM_ADD || rt->rtm_seq != seq || + rt->rtm_pid != pid)); + close(r); + if (cc == -1) { + logmsg(LOG_ERR, "rtmsg add read: %m"); + return; + } +} + +/* + * 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. + */ +static void +rarp_reply(struct if_info *ii, struct ether_header *ep, in_addr_t ipaddr, + u_int len) +{ + u_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) + logmsg(LOG_ERR, "write: only %d of %d bytes written", n, len); + if (verbose) + logmsg(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. + */ +static in_addr_t +ipaddrtonetmask(in_addr_t 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); + logmsg(LOG_DEBUG, "unknown IP address class: %08X", addr); + return htonl(0xffffffff); +} + +/* + * A faster replacement for inet_ntoa(). + */ +static char * +intoa(in_addr_t addr) +{ + char *cp; + u_int byte; + 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; +} + +static char * +eatoa(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); +} + +static void +logmsg(int pri, const char *fmt, ...) +{ + va_list v; + FILE *fp; + char *newfmt; + + va_start(v, fmt); + if (dflag) { + if (pri == LOG_ERR) + fp = stderr; + else + fp = stdout; + if (expand_syslog_m(fmt, &newfmt) == -1) { + vfprintf(fp, fmt, v); + } else { + vfprintf(fp, newfmt, v); + free(newfmt); + } + fputs("\n", fp); + fflush(fp); + } else { + vsyslog(pri, fmt, v); + } + va_end(v); +} + +static int +expand_syslog_m(const char *fmt, char **newfmt) { + const char *str, *m; + char *p, *np; + + p = strdup(""); + str = fmt; + while ((m = strstr(str, "%m")) != NULL) { + asprintf(&np, "%s%.*s%s", p, (int)(m - str), + str, strerror(errno)); + free(p); + if (np == NULL) { + errno = ENOMEM; + return (-1); + } + p = np; + str = m + 2; + } + + if (*str != '\0') { + asprintf(&np, "%s%s", p, str); + free(p); + if (np == NULL) { + errno = ENOMEM; + return (-1); + } + p = np; + } + + *newfmt = p; + return (0); +} |