| Current Path : /usr/src/usr.sbin/rarpd/ |
FreeBSD hs32.drive.ne.jp 9.1-RELEASE FreeBSD 9.1-RELEASE #1: Wed Jan 14 12:18:08 JST 2015 root@hs32.drive.ne.jp:/sys/amd64/compile/hs32 amd64 |
| Current File : //usr/src/usr.sbin/rarpd/rarpd.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
*
* 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.
*/
#if 0
#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 */
#endif
#include <sys/cdefs.h>
__FBSDID("$FreeBSD: release/9.1.0/usr.sbin/rarpd/rarpd.c 216225 2010-12-06 09:37:56Z glebius $");
/*
* rarpd - Reverse ARP Daemon
*
* Usage: rarpd -a [-dfsv] [-t directory] [hostname]
* rarpd [-dfsv] [-t directory] 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>
/* 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.
*/
struct if_info *iflist;
int verbose; /* verbose messages */
const char *tftp_dir = TFTP_DIR; /* tftp directory */
int dflag; /* messages to stdout/stderr, not syslog(3) */
int sflag; /* ignore /tftpboot */
static u_char zero[6];
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, *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 syslog, unless -d is specified
*/
openlog(name, LOG_PID | LOG_CONS, LOG_DAEMON);
opterr = 0;
while ((op = getopt(argc, argv, "adfst:v")) != -1)
switch (op) {
case 'a':
++aflag;
break;
case 'd':
++dflag;
break;
case 'f':
++fflag;
break;
case 's':
++sflag;
break;
case 't':
tftp_dir = optarg;
break;
case 'v':
++verbose;
break;
default:
usage();
/* NOTREACHED */
}
argc -= optind;
argv += optind;
ifname = (aflag == 0) ? argv[0] : NULL;
hostname = ifname ? argv[1] : argv[0];
if ((aflag && ifname) || (!aflag && ifname == NULL))
usage();
init(ifname);
if (!fflag) {
if (daemon(0,0)) {
logmsg(LOG_ERR, "cannot fork");
exit(1);
}
}
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");
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");
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;
if (ll->sdl_type == IFT_ETHER)
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");
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]",
" rarpd [-dfsv] [-t directory] 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);
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");
exit(1);
}
strlcpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
if (ioctl(fd, BIOCSETIF, (caddr_t)&ifr) == -1) {
logmsg(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) == -1) {
logmsg(LOG_ERR, "BIOCGDLT: %m");
exit(1);
}
if (dlt != DLT_EN10MB) {
logmsg(LOG_ERR, "%s is not an ethernet", device);
exit(1);
}
/*
* Set filter program.
*/
if (ioctl(fd, BIOCSETF, (caddr_t)&filter) == -1) {
logmsg(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(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");
exit(1);
}
if (ioctl(iflist->ii_fd, BIOCGBLEN, (caddr_t)&bufsize) == -1) {
logmsg(LOG_ERR, "BIOCGBLEN: %m");
exit(1);
}
buf = malloc(bufsize);
if (buf == NULL) {
logmsg(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) == -1) {
/* Don't choke when we get ptraced */
if (errno == EINTR)
continue;
logmsg(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 == -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
}
/*
* 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);
exit(1);
}
d = opendir(".");
if (d == NULL) {
logmsg(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.
*/
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 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).
*/
struct sockaddr_inarp sin_inarp = {
sizeof(struct sockaddr_inarp), AF_INET, 0,
{0},
{0},
0, 0
};
struct sockaddr_dl sin_dl = {
sizeof(struct sockaddr_dl), AF_LINK, 0, IFT_ETHER, 0, 6,
0, ""
};
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_inarp *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");
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) == -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_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_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);
}