/* $NetBSD: rarpd.c,v 1.61 2023/03/26 19:10:34 andvar Exp $ */
/*
* Copyright (c) 1990 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. 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.
*/
#include <sys/cdefs.h>
#ifndef lint
__COPYRIGHT("@(#) Copyright (c) 1990\
The Regents of the University of California. All rights reserved.");
#endif /* not lint */
#ifndef lint
__RCSID("$NetBSD: rarpd.c,v 1.61 2023/03/26 19:10:34 andvar Exp $");
#endif
/*
* rarpd - Reverse ARP Daemon
*
* Usage: rarpd -a [-d|-f] [-l]
* rarpd [-d|-f] [-l] interface [...]
*/
#include <sys/param.h>
#include <sys/file.h>
#include <sys/time.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <net/bpf.h>
#include <net/if.h>
#include <net/if_dl.h>
#ifdef __NetBSD__
#include <net/if_ether.h>
#endif
#include <net/if_types.h>
#include <netinet/in.h>
#ifdef __NetBSD__
#include <netinet/if_inarp.h>
#else
#include <netinet/if_ether.h>
#endif
#include <arpa/inet.h>
#include <errno.h>
#include <dirent.h>
#include <paths.h>
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>
#include <util.h>
#include <ifaddrs.h>
#define FATAL 1 /* fatal error occurred */
#define NONFATAL 0 /* non fatal error occurred */
/*
* The structure for each interface.
*/
struct if_info {
int ii_fd; /* BPF file descriptor */
u_char ii_eaddr[6]; /* Ethernet address of this interface */
u_int32_t ii_ipaddr; /* IP address of this interface */
u_int32_t ii_netmask; /* subnet or net mask */
char *ii_name; /* interface name */
struct if_info *ii_alias;
struct if_info *ii_next;
};
/*
* 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 u_int32_t choose_ipaddr(u_int32_t **, u_int32_t, u_int32_t);
static void debug(const char *,...) __printflike(1, 2);
static void init_some(char *name);
static void init_one(char *, u_int32_t);
static u_int32_t ipaddrtonetmask(u_int32_t);
static void lookup_eaddr(char *, u_char *);
static void lookup_ipaddr(char *, u_int32_t *, u_int32_t *);
static void rarp_loop(void) __dead;
static int rarp_open(char *);
static void rarp_process(struct if_info *, u_char *);
static void rarp_reply(struct if_info *, struct ether_header *, u_int32_t,
struct hostent *);
static void rarperr(int, const char *,...) __printflike(2, 3);
#if defined(__NetBSD__)
#include "mkarp.h"
#else
static void update_arptab(u_char *, u_int32_t);
#endif
__dead static void usage(void);
static int bpf_open(void);
static int rarp_check(u_char *, int);
#ifdef REQUIRE_TFTPBOOT
static int rarp_bootable(u_int32_t);
#endif
static int aflag = 0; /* listen on "all" interfaces */
static int dflag = 0; /* print debugging messages */
static int fflag = 0; /* don't fork */
static int lflag = 0; /* log all replies */
int
main(int argc, char **argv)
{
int op;
setprogname(*argv);
/* All error reporting is done through syslogs. */
openlog(getprogname(), LOG_PID, LOG_DAEMON);
opterr = 0;
while ((op = getopt(argc, argv, "adfl")) != -1) {
switch (op) {
case 'a':
++aflag;
break;
case 'd':
++dflag;
break;
case 'f':
++fflag;
break;
case 'l':
++lflag;
break;
default:
usage();
/* NOTREACHED */
}
}
argc -= optind;
argv += optind;
if ((aflag && argc != 0) || (!aflag && argc == 0))
usage();
if ((!fflag) && (!dflag)) {
if (daemon(0, 0))
rarperr(FATAL, "daemon");
pidfile(NULL);
}
if (aflag)
init_some(NULL);
else {
while (argc--)
init_some(*argv++);
}
rarp_loop();
/* NOTREACHED */
return (0);
}
/*
* Add 'ifname' to the interface list. Lookup its IP address and network
* mask and Ethernet address, and open a BPF file for it.
*/
static void
init_one(char *ifname, u_int32_t ipaddr)
{
struct if_info *h;
struct if_info *p;
int fd;
for (h = iflist; h != NULL; h = h->ii_next) {
if (!strcmp(h->ii_name, ifname))
break;
}
if (h == NULL) {
fd = rarp_open(ifname);
if (fd < 0)
return;
} else {
fd = h->ii_fd;
}
p = (struct if_info *)malloc(sizeof(*p));
if (p == 0) {
rarperr(FATAL, "malloc: %s", strerror(errno));
/* NOTREACHED */
}
p->ii_name = strdup(ifname);
if (p->ii_name == 0) {
rarperr(FATAL, "malloc: %s", strerror(errno));
/* NOTREACHED */
}
if (h != NULL) {
p->ii_alias = h->ii_alias;
h->ii_alias = p;
} else {
p->ii_next = iflist;
iflist = p;
}
p->ii_fd = fd;
p->ii_ipaddr = ipaddr;
lookup_eaddr(ifname, p->ii_eaddr);
lookup_ipaddr(ifname, &p->ii_ipaddr, &p->ii_netmask);
}
/*
* 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_some(char *name)
{
struct ifaddrs *ifap, *ifa, *p;
if (getifaddrs(&ifap) != 0) {
rarperr(FATAL, "getifaddrs: %s", strerror(errno));
/* NOTREACHED */
}
p = NULL;
for (ifa = ifap; ifa; ifa = ifa->ifa_next) {
#define SIN(s) ((struct sockaddr_in *) (s))
if (ifa->ifa_addr->sa_family != AF_INET)
continue;
if (name && strcmp(name, ifa->ifa_name))
continue;
if (p && !strcmp(p->ifa_name, ifa->ifa_name) &&
SIN(p->ifa_addr)->sin_addr.s_addr == SIN(ifa->ifa_addr)->sin_addr.s_addr)
continue;
p = ifa;
if ((ifa->ifa_flags &
(IFF_UP | IFF_LOOPBACK | IFF_POINTOPOINT)) != IFF_UP)
continue;
init_one(ifa->ifa_name, SIN(ifa->ifa_addr)->sin_addr.s_addr);
#undef SIN
}
freeifaddrs(ifap);
}
static void
usage(void)
{
(void) fprintf(stderr, "Usage: %s -a [-d|-f] [-l]\n", getprogname());
(void) fprintf(stderr, "\t%s [-d|-f] [-l] interface [...]\n",
getprogname());
exit(1);
}
static int
bpf_open(void)
{
int fd;
const char *device = _PATH_BPF;
fd = open(device, O_RDWR);
if (fd < 0) {
rarperr(FATAL, "%s: %s", device, strerror(errno));
/* NOTREACHED */
}
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;
u_int bufsize;
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, ARPOP_REVREQUEST, 0, 1),
BPF_STMT(BPF_RET | BPF_K,
sizeof(struct arphdr) +
2 * ETHER_ADDR_LEN + 2 * sizeof(struct in_addr) +
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) {
rarperr(FATAL, "BIOCIMMEDIATE: %s", strerror(errno));
/* NOTREACHED */
}
/* Set a 32k buffer size for kernel use */
bufsize = 32768;
if (ioctl(fd, BIOCSBLEN, &bufsize) < 0) {
rarperr(NONFATAL, "BIOCSBLEN:%d: %s", bufsize, strerror(errno));
}
(void)strlcpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
if (ioctl(fd, BIOCSETIF, (caddr_t) & ifr) < 0) {
if (aflag) { /* for -a skip non-ethernet interfaces */
close(fd);
return(-1);
}
rarperr(FATAL, "BIOCSETIF: %s", strerror(errno));
/* NOTREACHED */
}
/* 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) {
rarperr(FATAL, "BIOCGDLT: %s", strerror(errno));
/* NOTREACHED */
}
if (dlt != DLT_EN10MB) {
if (aflag) { /* for -a skip non-ethernet interfaces */
close(fd);
return(-1);
}
rarperr(FATAL, "%s is not an ethernet", device);
/* NOTREACHED */
}
/* Set filter program. */
if (ioctl(fd, BIOCSETF, (caddr_t) & filter) < 0) {
rarperr(FATAL, "BIOCSETF: %s", strerror(errno));
/* NOTREACHED */
}
return fd;
}
/*
* Perform various sanity checks on the RARP request packet. Return
* false on failure and log the reason.
*/
static int
rarp_check(u_char *p, int len)
{
struct ether_header *ep = (struct ether_header *) p;
#ifdef __NetBSD__
struct arphdr *ap = (struct arphdr *) (p + sizeof(*ep));
#else
struct ether_arp *ap = (struct ether_arp *) (p + sizeof(*ep));
#endif
if (len < (int)(sizeof(*ep) + sizeof(*ap))) {
rarperr(NONFATAL, "truncated request");
return 0;
}
#ifdef __NetBSD__
/* now that we know the fixed part of the ARP hdr is there: */
if (len < (int)(sizeof(*ap) + 2 * ap->ar_hln + 2 * ap->ar_pln)) {
rarperr(NONFATAL, "truncated request");
return 0;
}
#endif
/* XXX This test might be better off broken out... */
#ifdef __FreeBSD__
/* BPF (incorrectly) returns this in host order. */
if (ep->ether_type != ETHERTYPE_REVARP ||
#else
if (ntohs (ep->ether_type) != ETHERTYPE_REVARP ||
#endif
#ifdef __NetBSD__
ntohs (ap->ar_hrd) != ARPHRD_ETHER ||
ntohs (ap->ar_op) != ARPOP_REVREQUEST ||
ntohs (ap->ar_pro) != ETHERTYPE_IP ||
ap->ar_hln != 6 || ap->ar_pln != 4) {
#else
ntohs (ap->arp_hrd) != ARPHRD_ETHER ||
ntohs (ap->arp_op) != ARPOP_REVREQUEST ||
ntohs (ap->arp_pro) != ETHERTYPE_IP ||
ap->arp_hln != 6 || ap->arp_pln != 4) {
#endif
rarperr(NONFATAL, "request fails sanity check");
return 0;
}
#ifdef __NetBSD__
if (memcmp((char *) &ep->ether_shost, ar_sha(ap), 6) != 0) {
#else
if (memcmp((char *) &ep->ether_shost, ap->arp_sha, 6) != 0) {
#endif
rarperr(NONFATAL, "ether/arp sender address mismatch");
return 0;
}
{
#ifdef __NetBSD__
uint8_t *tha = ar_tha(ap);
if (!tha || memcmp(ar_sha(ap), tha, 6) != 0) {
#else
if (memcmp((char *) &ap->arp_sha, (char *) &ap->arp_tha, 6) != 0) {
#endif
rarperr(NONFATAL, "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 == 0) {
rarperr(FATAL, "no interfaces");
/* NOTREACHED */
}
if (ioctl(iflist->ii_fd, BIOCGBLEN, (caddr_t) & bufsize) < 0) {
rarperr(FATAL, "BIOCGBLEN: %s", strerror(errno));
/* NOTREACHED */
}
buf = (u_char *) malloc((unsigned) bufsize);
if (buf == 0) {
rarperr(FATAL, "malloc: %s", strerror(errno));
/* NOTREACHED */
}
/*
* Find the highest numbered file descriptor for select().
* Initialize the set of descriptors to listen to.
*/
FD_ZERO(&fds);
for (ii = iflist; ii; ii = ii->ii_next) {
FD_SET(ii->ii_fd, &fds);
if (ii->ii_fd > maxfd)
maxfd = ii->ii_fd;
}
while (1) {
listeners = fds;
if (select(maxfd + 1, &listeners, (struct fd_set *) 0,
(struct fd_set *) 0, (struct timeval *) 0) < 0) {
rarperr(FATAL, "select: %s", strerror(errno));
/* NOTREACHED */
}
for (ii = iflist; ii; 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;
/* 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 &&
(lseek(fd, 0, SEEK_CUR) + bufsize) < 0) {
(void)lseek(fd, 0, 0);
goto again;
}
rarperr(FATAL, "read: %s", strerror(errno));
/* NOTREACHED */
}
/* Loop through the packet(s) */
#define bhp ((struct bpf_hdr *)bp)
bp = buf;
ep = bp + cc;
while (bp < ep) {
int caplen, hdrlen;
caplen = bhp->bh_caplen;
hdrlen = bhp->bh_hdrlen;
debug("received packet on %s", ii->ii_name);
if (rarp_check(bp + hdrlen, caplen))
rarp_process(ii, bp + hdrlen);
bp += BPF_WORDALIGN(hdrlen + caplen);
}
}
}
}
#ifdef REQUIRE_TFTPBOOT
#ifndef TFTP_DIR
#define TFTP_DIR "/tftpboot"
#endif
/*
* 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(u_int32_t addr)
{
struct dirent *dent;
DIR *d;
char ipname[9];
static DIR *dd = 0;
(void)snprintf(ipname, sizeof(ipname), "%08X", addr);
/* If directory is already open, rewind it. Otherwise, open it. */
if (d = dd)
rewinddir(d);
else {
if (chdir(TFTP_DIR) == -1) {
rarperr(FATAL, "chdir: %s", strerror(errno));
/* NOTREACHED */
}
d = opendir(".");
if (d == 0) {
rarperr(FATAL, "opendir: %s", strerror(errno));
/* NOTREACHED */
}
dd = d;
}
while (dent = readdir(d))
if (strncmp(dent->d_name, ipname, 8) == 0)
return 1;
return 0;
}
#endif /* REQUIRE_TFTPBOOT */
/*
* 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 u_int32_t
choose_ipaddr(u_int32_t **alist, u_int32_t net, u_int32_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)
{
struct ether_header *ep;
struct hostent *hp;
u_int32_t target_ipaddr = 0;
char ename[MAXHOSTNAMELEN + 1];
struct in_addr in;
ep = (struct ether_header *) pkt;
if (ether_ntohost(ename, (struct ether_addr *)&ep->ether_shost) != 0) {
debug("no IP address for %s",
ether_ntoa((struct ether_addr *)&ep->ether_shost));
return;
}
ename[sizeof(ename)-1] = '\0';
if ((hp = gethostbyname(ename)) == 0) {
debug("gethostbyname(%s) failed: %s", ename,
hstrerror(h_errno));
return;
}
/* Choose correct address from list. */
if (hp->h_addrtype != AF_INET) {
rarperr(FATAL, "cannot handle non IP addresses");
/* NOTREACHED */
}
for (;; ii = ii->ii_alias) {
target_ipaddr = choose_ipaddr((u_int32_t **) hp->h_addr_list,
ii->ii_ipaddr & ii->ii_netmask, ii->ii_netmask);
if (target_ipaddr != 0)
break;
if (ii->ii_alias == NULL)
break;
}
if (target_ipaddr == 0) {
in.s_addr = ii->ii_ipaddr & ii->ii_netmask;
rarperr(NONFATAL, "cannot find %s on net %s",
ename, inet_ntoa(in));
return;
}
#ifdef REQUIRE_TFTPBOOT
if (rarp_bootable(htonl(target_ipaddr)))
#endif
rarp_reply(ii, ep, target_ipaddr, hp);
#ifdef REQUIRE_TFTPBOOT
else
debug("%08X not bootable", htonl(target_ipaddr));
#endif
}
/*
* Lookup the ethernet address of the interface attached to the BPF
* file descriptor 'fd'; return it in 'eaddr'.
*/
static void
lookup_eaddr(char *ifname, u_char *eaddr)
{
struct ifaddrs *ifap, *ifa;
struct sockaddr_dl *sdl;
if (getifaddrs(&ifap) != 0) {
rarperr(FATAL, "getifaddrs: %s", strerror(errno));
/* NOTREACHED */
}
for (ifa = ifap; ifa; ifa = ifa->ifa_next) {
sdl = (struct sockaddr_dl *)ifa->ifa_addr;
if (sdl->sdl_family != AF_LINK || sdl->sdl_type != IFT_ETHER ||
sdl->sdl_alen != 6)
continue;
if (!strcmp(ifa->ifa_name, ifname)) {
memmove((caddr_t)eaddr, (caddr_t)LLADDR(sdl), 6);
debug("%s: %x:%x:%x:%x:%x:%x",
ifa->ifa_name, eaddr[0], eaddr[1],
eaddr[2], eaddr[3], eaddr[4], eaddr[5]);
freeifaddrs(ifap);
return;
}
}
rarperr(FATAL, "lookup_eaddr: Never saw interface `%s'!", ifname);
freeifaddrs(ifap);
}
/*
* Lookup the IP address and network mask of the interface named 'ifname'.
*/
static void
lookup_ipaddr(char *ifname, u_int32_t *addrp, u_int32_t *netmaskp)
{
int fd;
/* Use datagram socket to get IP address. */
if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
rarperr(FATAL, "socket: %s", strerror(errno));
/* NOTREACHED */
}
if (*addrp == INADDR_ANY) {
struct ifreq ifr;
memset(&ifr, 0, sizeof(ifr));
(void)strncpy(ifr.ifr_name, ifname, sizeof ifr.ifr_name);
if (ioctl(fd, SIOCGIFADDR, (char *) &ifr) < 0) {
rarperr(FATAL, "SIOCGIFADDR: %s", strerror(errno));
/* NOTREACHED */
}
*addrp = ((struct sockaddr_in *) & ifr.ifr_addr)->sin_addr.s_addr;
if (ioctl(fd, SIOCGIFNETMASK, (char *) &ifr) < 0) {
perror("SIOCGIFNETMASK");
exit(1);
}
*netmaskp = ((struct sockaddr_in *) & ifr.ifr_addr)->sin_addr.s_addr;
} else {
struct ifaliasreq ifra;
memset(&ifra, 0, sizeof(ifra));
(void)strncpy(ifra.ifra_name, ifname, sizeof ifra.ifra_name);
((struct sockaddr_in *) & ifra.ifra_addr)->sin_family = AF_INET;
((struct sockaddr_in *) & ifra.ifra_addr)->sin_addr.s_addr = *addrp;
if (ioctl(fd, SIOCGIFALIAS, (char *) &ifra) < 0) {
rarperr(FATAL, "SIOCGIFALIAS: %s", strerror(errno));
/* NOTREACHED */
}
*addrp = ((struct sockaddr_in *) & ifra.ifra_addr)->sin_addr.s_addr;
*netmaskp = ((struct sockaddr_in *) & ifra.ifra_mask)->sin_addr.s_addr;
}
/* If SIOCGIFNETMASK didn't work, figure out a mask from the IP
* address class. */
if (*netmaskp == 0)
*netmaskp = ipaddrtonetmask(*addrp);
(void)close(fd);
}
/*
* 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).
*/
#ifndef __NetBSD__
static void
update_arptab(u_char *ep, u_int32_t 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;
/* This is needed #if defined(COMPAT_43) && BYTE_ORDER != BIG_ENDIAN,
because AF_UNSPEC is zero and the kernel assumes that a zero
sa_family means that the real sa_family value is in sa_len. */
request.arp_ha.sa_len = 16; /* XXX */
memmove((char *) request.arp_ha.sa_data, (char *)ep, 6);
#if 0
s = socket(AF_INET, SOCK_DGRAM, 0);
if (ioctl(s, SIOCSARP, (caddr_t) & request) < 0) {
rarperr(NONFATAL, "SIOCSARP: %s", strerror(errno));
}
(void)close(s);
#endif
}
#endif
/*
* Build a reverse ARP packet and sent it out on the interface.
* 'ep' points to a valid ARPOP_REVREQUEST. The ARPOP_REVREPLY 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.
*
* ARPOP_REVREQUEST
*
* 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.
*
* ARPOP_REVREPLY
*
* 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, u_int32_t ipaddr,
struct hostent *hp)
{
int n;
#ifdef __NetBSD__
struct arphdr *ap = (struct arphdr *) (ep + 1);
#else
struct ether_arp *ap = (struct ether_arp *) (ep + 1);
#endif
int len;
#ifdef __NetBSD__
(void)mkarp((u_int8_t *)ar_sha(ap), ipaddr);
#else
update_arptab((u_char *) & ap->arp_sha, ipaddr);
#endif
/* Build the rarp reply by modifying the rarp request in place. */
#ifdef __FreeBSD__
/* BPF (incorrectly) wants this in host order. */
ep->ether_type = ETHERTYPE_REVARP;
#else
ep->ether_type = htons(ETHERTYPE_REVARP);
#endif
#ifdef __NetBSD__
ap->ar_hrd = htons(ARPHRD_ETHER);
ap->ar_pro = htons(ETHERTYPE_IP);
ap->ar_op = htons(ARPOP_REVREPLY);
memmove((char *) &ep->ether_dhost, ar_sha(ap), 6);
memmove((char *) &ep->ether_shost, (char *) ii->ii_eaddr, 6);
memmove(ar_sha(ap), (char *) ii->ii_eaddr, 6);
memmove(ar_tpa(ap), (char *) &ipaddr, 4);
/* Target hardware is unchanged. */
memmove(ar_spa(ap), (char *) &ii->ii_ipaddr, 4);
len = sizeof(*ep) + sizeof(*ap) +
2 * ap->ar_pln + 2 * ap->ar_hln;
#else
ap->ea_hdr.ar_hrd = htons(ARPHRD_ETHER);
ap->ea_hdr.ar_pro = htons(ETHERTYPE_IP);
ap->arp_op = htons(ARPOP_REVREPLY);
memmove((char *) &ep->ether_dhost, (char *) &ap->arp_sha, 6);
memmove((char *) &ep->ether_shost, (char *) ii->ii_eaddr, 6);
memmove((char *) &ap->arp_sha, (char *) ii->ii_eaddr, 6);
memmove((char *) ap->arp_tpa, (char *) &ipaddr, 4);
/* Target hardware is unchanged. */
memmove((char *) ap->arp_spa, (char *) &ii->ii_ipaddr, 4);
len = sizeof(*ep) + sizeof(*ap);
#endif
debug("%s asked; %s replied",
ether_ntoa((struct ether_addr *)ar_tha(ap)), hp->h_name);
if (lflag)
syslog(LOG_INFO, "%s asked; %s replied",
ether_ntoa((struct ether_addr *)ar_tha(ap)), hp->h_name);
n = write(ii->ii_fd, (char *) ep, len);
if (n != len) {
rarperr(NONFATAL, "write: only %d of %d bytes written", n, len);
}
}
/*
* Get the netmask of an IP address. This routine is used if
* SIOCGIFNETMASK doesn't work.
*/
static u_int32_t
ipaddrtonetmask(u_int32_t addr)
{
if (IN_CLASSA(addr))
return IN_CLASSA_NET;
if (IN_CLASSB(addr))
return IN_CLASSB_NET;
if (IN_CLASSC(addr))
return IN_CLASSC_NET;
rarperr(FATAL, "unknown IP address class: %08X", addr);
/* NOTREACHED */
return(-1);
}
#include <stdarg.h>
static void
rarperr(int fatal, const char *fmt,...)
{
va_list ap;
va_start(ap, fmt);
if (dflag) {
if (fatal)
(void)fprintf(stderr, "%s: error: ", getprogname());
else
(void)fprintf(stderr, "%s: warning: ", getprogname());
(void)vfprintf(stderr, fmt, ap);
va_end(ap);
va_start(ap, fmt);
(void)fprintf(stderr, "\n");
}
vsyslog(LOG_ERR, fmt, ap);
va_end(ap);
if (fatal)
exit(1);
/* NOTREACHED */
}
static void
debug(const char *fmt,...)
{
va_list ap;
va_start(ap, fmt);
if (dflag) {
(void)fprintf(stderr, "%s: ", getprogname());
(void)vfprintf(stderr, fmt, ap);
va_end(ap);
va_start(ap, fmt);
(void)fprintf(stderr, "\n");
}
vsyslog(LOG_WARNING, fmt, ap);
va_end(ap);
}
