freebsd-dev/usr.sbin/rarpd/rarpd.c
1997-03-31 05:11:47 +00:00

1010 lines
24 KiB
C

/*
* 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
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[] =
"$Id: rarpd.c,v 1.15 1997/02/22 16:12:44 peter Exp $";
#endif
/*
* 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 <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/if.h>
#include <net/if_var.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 <errno.h>
#include <netdb.h>
#include <stdio.h>
#include <string.h>
#include <syslog.h>
#include <stdlib.h>
#include <unistd.h>
#if defined(SUNOS4) || defined(__FreeBSD__) /* XXX */
#define HAVE_DIRENT_H
#endif
#ifdef HAVE_DIRENT_H
#include <dirent.h>
#else
#include <sys/dir.h>
#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));
void usage __P((void));
static u_char zero[6];
int sflag = 0; /* ignore /tftpboot */
void
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();
}
/*
* 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));
}
void
usage()
{
(void)fprintf(stderr, "usage: rarpd [ -afnv ] [ 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;
static int r, seq;
static init = 0;
if (!init) {
r = socket(PF_ROUTE, SOCK_RAW, 0);
if (r < 0) {
syslog(LOG_ERR, "raw route socket: %m");
exit(1);
}
pid = getpid();
++init;
}
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");
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");
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);
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");
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 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);
}