iproute2/misc/arpd.c
Phil Sutter d17b136f7d Use C99 style initializers everywhere
This big patch was compiled by vimgrepping for memset calls and changing
to C99 initializer if applicable. One notable exception is the
initialization of union bpf_attr in tc/tc_bpf.c: changing it would break
for older gcc versions (at least <=3.4.6).

Calls to memset for struct rtattr pointer fields for parse_rtattr*()
were just dropped since they are not needed.

The changes here allowed the compiler to discover some unused variables,
so get rid of them, too.

Signed-off-by: Phil Sutter <phil@nwl.cc>
Acked-by: David Ahern <dsa@cumulusnetworks.com>
2016-07-20 12:05:24 -07:00

839 lines
17 KiB
C

/*
* arpd.c ARP helper daemon.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
*/
#include <stdio.h>
#include <syslog.h>
#include <malloc.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>
#include <netdb.h>
#include <db_185.h>
#include <sys/ioctl.h>
#include <sys/poll.h>
#include <errno.h>
#include <fcntl.h>
#include <sys/uio.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <time.h>
#include <signal.h>
#include <linux/if.h>
#include <linux/if_ether.h>
#include <linux/if_arp.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <linux/if_packet.h>
#include <linux/filter.h>
#include "libnetlink.h"
#include "utils.h"
#include "rt_names.h"
int resolve_hosts;
DB *dbase;
char *dbname = "/var/lib/arpd/arpd.db";
int ifnum;
int *ifvec;
char **ifnames;
struct dbkey {
__u32 iface;
__u32 addr;
};
#define IS_NEG(x) (((__u8 *)(x))[0] == 0xFF)
#define NEG_TIME(x) (((x)[2]<<24)|((x)[3]<<16)|((x)[4]<<8)|(x)[5])
#define NEG_AGE(x) ((__u32)time(NULL) - NEG_TIME((__u8 *)x))
#define NEG_VALID(x) (NEG_AGE(x) < negative_timeout)
#define NEG_CNT(x) (((__u8 *)(x))[1])
struct rtnl_handle rth;
struct pollfd pset[2];
int udp_sock = -1;
volatile int do_exit;
volatile int do_sync;
volatile int do_stats;
struct {
unsigned long arp_new;
unsigned long arp_change;
unsigned long app_recv;
unsigned long app_success;
unsigned long app_bad;
unsigned long app_neg;
unsigned long app_suppressed;
unsigned long kern_neg;
unsigned long kern_new;
unsigned long kern_change;
unsigned long probes_sent;
unsigned long probes_suppressed;
} stats;
int active_probing;
int negative_timeout = 60;
int no_kernel_broadcasts;
int broadcast_rate = 1000;
int broadcast_burst = 3000;
int poll_timeout = 30000;
static void usage(void)
{
fprintf(stderr,
"Usage: arpd [ -lkh? ] [ -a N ] [ -b dbase ] [ -B number ] [ -f file ] [ -n time ] [-p interval ] [ -R rate ] [ interfaces ]\n");
exit(1);
}
static int handle_if(int ifindex)
{
int i;
if (ifnum == 0)
return 1;
for (i = 0; i < ifnum; i++)
if (ifvec[i] == ifindex)
return 1;
return 0;
}
int sysctl_adjusted;
static void do_sysctl_adjustments(void)
{
int i;
if (!ifnum)
return;
for (i = 0; i < ifnum; i++) {
char buf[128];
FILE *fp;
if (active_probing) {
sprintf(buf, "/proc/sys/net/ipv4/neigh/%s/mcast_solicit", ifnames[i]);
if ((fp = fopen(buf, "w")) != NULL) {
if (no_kernel_broadcasts)
strcpy(buf, "0\n");
else
sprintf(buf, "%d\n", active_probing >= 2 ? 1 : 3-active_probing);
fputs(buf, fp);
fclose(fp);
}
}
sprintf(buf, "/proc/sys/net/ipv4/neigh/%s/app_solicit", ifnames[i]);
if ((fp = fopen(buf, "w")) != NULL) {
sprintf(buf, "%d\n", active_probing <= 1 ? 1 : active_probing);
fputs(buf, fp);
fclose(fp);
}
}
sysctl_adjusted = 1;
}
static void undo_sysctl_adjustments(void)
{
int i;
if (!sysctl_adjusted)
return;
for (i = 0; i < ifnum; i++) {
char buf[128];
FILE *fp;
if (active_probing) {
sprintf(buf, "/proc/sys/net/ipv4/neigh/%s/mcast_solicit", ifnames[i]);
if ((fp = fopen(buf, "w")) != NULL) {
strcpy(buf, "3\n");
fputs(buf, fp);
fclose(fp);
}
}
sprintf(buf, "/proc/sys/net/ipv4/neigh/%s/app_solicit", ifnames[i]);
if ((fp = fopen(buf, "w")) != NULL) {
strcpy(buf, "0\n");
fputs(buf, fp);
fclose(fp);
}
}
sysctl_adjusted = 0;
}
static int send_probe(int ifindex, __u32 addr)
{
struct ifreq ifr = { .ifr_ifindex = ifindex };
struct sockaddr_in dst = {
.sin_family = AF_INET,
.sin_port = htons(1025),
.sin_addr.s_addr = addr,
};
socklen_t len;
unsigned char buf[256];
struct arphdr *ah = (struct arphdr *)buf;
unsigned char *p = (unsigned char *)(ah+1);
struct sockaddr_ll sll = {
.sll_family = AF_PACKET,
.sll_ifindex = ifindex,
.sll_protocol = htons(ETH_P_ARP),
};
if (ioctl(udp_sock, SIOCGIFNAME, &ifr))
return -1;
if (ioctl(udp_sock, SIOCGIFHWADDR, &ifr))
return -1;
if (ifr.ifr_hwaddr.sa_family != ARPHRD_ETHER)
return -1;
if (setsockopt(udp_sock, SOL_SOCKET, SO_BINDTODEVICE, ifr.ifr_name, strlen(ifr.ifr_name)+1) < 0)
return -1;
if (connect(udp_sock, (struct sockaddr *)&dst, sizeof(dst)) < 0)
return -1;
len = sizeof(dst);
if (getsockname(udp_sock, (struct sockaddr *)&dst, &len) < 0)
return -1;
ah->ar_hrd = htons(ifr.ifr_hwaddr.sa_family);
ah->ar_pro = htons(ETH_P_IP);
ah->ar_hln = 6;
ah->ar_pln = 4;
ah->ar_op = htons(ARPOP_REQUEST);
memcpy(p, ifr.ifr_hwaddr.sa_data, ah->ar_hln);
p += ah->ar_hln;
memcpy(p, &dst.sin_addr, 4);
p += 4;
memset(sll.sll_addr, 0xFF, sizeof(sll.sll_addr));
memcpy(p, &sll.sll_addr, ah->ar_hln);
p += ah->ar_hln;
memcpy(p, &addr, 4);
p += 4;
if (sendto(pset[0].fd, buf, p-buf, 0, (struct sockaddr *)&sll, sizeof(sll)) < 0)
return -1;
stats.probes_sent++;
return 0;
}
/* Be very tough on sending probes: 1 per second with burst of 3. */
static int queue_active_probe(int ifindex, __u32 addr)
{
static struct timeval prev;
static int buckets;
struct timeval now;
gettimeofday(&now, NULL);
if (prev.tv_sec) {
int diff = (now.tv_sec-prev.tv_sec)*1000+(now.tv_usec-prev.tv_usec)/1000;
buckets += diff;
} else {
buckets = broadcast_burst;
}
if (buckets > broadcast_burst)
buckets = broadcast_burst;
if (buckets >= broadcast_rate && !send_probe(ifindex, addr)) {
buckets -= broadcast_rate;
prev = now;
return 0;
}
stats.probes_suppressed++;
return -1;
}
static int respond_to_kernel(int ifindex, __u32 addr, char *lla, int llalen)
{
struct {
struct nlmsghdr n;
struct ndmsg ndm;
char buf[256];
} req = {
.n.nlmsg_len = NLMSG_LENGTH(sizeof(struct ndmsg)),
.n.nlmsg_flags = NLM_F_REQUEST,
.n.nlmsg_type = RTM_NEWNEIGH,
.ndm.ndm_family = AF_INET,
.ndm.ndm_state = NUD_STALE,
.ndm.ndm_ifindex = ifindex,
.ndm.ndm_type = RTN_UNICAST,
};
addattr_l(&req.n, sizeof(req), NDA_DST, &addr, 4);
addattr_l(&req.n, sizeof(req), NDA_LLADDR, lla, llalen);
return rtnl_send(&rth, &req, req.n.nlmsg_len) <= 0;
}
static void prepare_neg_entry(__u8 *ndata, __u32 stamp)
{
ndata[0] = 0xFF;
ndata[1] = 0;
ndata[2] = stamp>>24;
ndata[3] = stamp>>16;
ndata[4] = stamp>>8;
ndata[5] = stamp;
}
static int do_one_request(struct nlmsghdr *n)
{
struct ndmsg *ndm = NLMSG_DATA(n);
int len = n->nlmsg_len;
struct rtattr *tb[NDA_MAX+1];
struct dbkey key;
DBT dbkey, dbdat;
int do_acct = 0;
if (n->nlmsg_type == NLMSG_DONE) {
dbase->sync(dbase, 0);
/* Now we have at least mirror of kernel db, so that
* may start real resolution.
*/
do_sysctl_adjustments();
return 0;
}
if (n->nlmsg_type != RTM_GETNEIGH && n->nlmsg_type != RTM_NEWNEIGH)
return 0;
len -= NLMSG_LENGTH(sizeof(*ndm));
if (len < 0)
return -1;
if (ndm->ndm_family != AF_INET ||
(ifnum && !handle_if(ndm->ndm_ifindex)) ||
ndm->ndm_flags ||
ndm->ndm_type != RTN_UNICAST ||
!(ndm->ndm_state&~NUD_NOARP))
return 0;
parse_rtattr(tb, NDA_MAX, NDA_RTA(ndm), len);
if (!tb[NDA_DST])
return 0;
key.iface = ndm->ndm_ifindex;
memcpy(&key.addr, RTA_DATA(tb[NDA_DST]), 4);
dbkey.data = &key;
dbkey.size = sizeof(key);
if (dbase->get(dbase, &dbkey, &dbdat, 0) != 0) {
dbdat.data = 0;
dbdat.size = 0;
}
if (n->nlmsg_type == RTM_GETNEIGH) {
if (!(n->nlmsg_flags&NLM_F_REQUEST))
return 0;
if (!(ndm->ndm_state&(NUD_PROBE|NUD_INCOMPLETE))) {
stats.app_bad++;
return 0;
}
if (ndm->ndm_state&NUD_PROBE) {
/* If we get this, kernel still has some valid
* address, but unicast probing failed and host
* is either dead or changed its mac address.
* Kernel is going to initiate broadcast resolution.
* OK, we invalidate our information as well.
*/
if (dbdat.data && !IS_NEG(dbdat.data))
stats.app_neg++;
dbase->del(dbase, &dbkey, 0);
} else {
/* If we get this kernel does not have any information.
* If we have something tell this to kernel. */
stats.app_recv++;
if (dbdat.data && !IS_NEG(dbdat.data)) {
stats.app_success++;
respond_to_kernel(key.iface, key.addr, dbdat.data, dbdat.size);
return 0;
}
/* Sheeit! We have nothing to tell. */
/* If we have recent negative entry, be silent. */
if (dbdat.data && NEG_VALID(dbdat.data)) {
if (NEG_CNT(dbdat.data) >= active_probing) {
stats.app_suppressed++;
return 0;
}
do_acct = 1;
}
}
if (active_probing &&
queue_active_probe(ndm->ndm_ifindex, key.addr) == 0 &&
do_acct) {
NEG_CNT(dbdat.data)++;
dbase->put(dbase, &dbkey, &dbdat, 0);
}
} else if (n->nlmsg_type == RTM_NEWNEIGH) {
if (n->nlmsg_flags&NLM_F_REQUEST)
return 0;
if (ndm->ndm_state&NUD_FAILED) {
/* Kernel was not able to resolve. Host is dead.
* Create negative entry if it is not present
* or renew it if it is too old. */
if (!dbdat.data ||
!IS_NEG(dbdat.data) ||
!NEG_VALID(dbdat.data)) {
__u8 ndata[6];
stats.kern_neg++;
prepare_neg_entry(ndata, time(NULL));
dbdat.data = ndata;
dbdat.size = sizeof(ndata);
dbase->put(dbase, &dbkey, &dbdat, 0);
}
} else if (tb[NDA_LLADDR]) {
if (dbdat.data && !IS_NEG(dbdat.data)) {
if (memcmp(RTA_DATA(tb[NDA_LLADDR]), dbdat.data, dbdat.size) == 0)
return 0;
stats.kern_change++;
} else {
stats.kern_new++;
}
dbdat.data = RTA_DATA(tb[NDA_LLADDR]);
dbdat.size = RTA_PAYLOAD(tb[NDA_LLADDR]);
dbase->put(dbase, &dbkey, &dbdat, 0);
}
}
return 0;
}
static void load_initial_table(void)
{
if (rtnl_wilddump_request(&rth, AF_INET, RTM_GETNEIGH) < 0) {
perror("dump request failed");
exit(1);
}
}
static void get_kern_msg(void)
{
int status;
struct nlmsghdr *h;
struct sockaddr_nl nladdr = {};
struct iovec iov;
char buf[8192];
struct msghdr msg = {
(void *)&nladdr, sizeof(nladdr),
&iov, 1,
NULL, 0,
0
};
iov.iov_base = buf;
iov.iov_len = sizeof(buf);
status = recvmsg(rth.fd, &msg, MSG_DONTWAIT);
if (status <= 0)
return;
if (msg.msg_namelen != sizeof(nladdr))
return;
if (nladdr.nl_pid)
return;
for (h = (struct nlmsghdr *)buf; status >= sizeof(*h); ) {
int len = h->nlmsg_len;
int l = len - sizeof(*h);
if (l < 0 || len > status)
return;
if (do_one_request(h) < 0)
return;
status -= NLMSG_ALIGN(len);
h = (struct nlmsghdr *)((char *)h + NLMSG_ALIGN(len));
}
}
/* Receive gratuitous ARP messages and store them, that's all. */
static void get_arp_pkt(void)
{
unsigned char buf[1024];
struct sockaddr_ll sll;
socklen_t sll_len = sizeof(sll);
struct arphdr *a = (struct arphdr *)buf;
struct dbkey key;
DBT dbkey, dbdat;
int n;
n = recvfrom(pset[0].fd, buf, sizeof(buf), MSG_DONTWAIT,
(struct sockaddr *)&sll, &sll_len);
if (n < 0) {
if (errno != EINTR && errno != EAGAIN)
syslog(LOG_ERR, "recvfrom: %m");
return;
}
if (ifnum && !handle_if(sll.sll_ifindex))
return;
/* Sanity checks */
if (n < sizeof(*a) ||
(a->ar_op != htons(ARPOP_REQUEST) &&
a->ar_op != htons(ARPOP_REPLY)) ||
a->ar_pln != 4 ||
a->ar_pro != htons(ETH_P_IP) ||
a->ar_hln != sll.sll_halen ||
sizeof(*a) + 2*4 + 2*a->ar_hln > n)
return;
key.iface = sll.sll_ifindex;
memcpy(&key.addr, (char *)(a+1) + a->ar_hln, 4);
/* DAD message, ignore. */
if (key.addr == 0)
return;
dbkey.data = &key;
dbkey.size = sizeof(key);
if (dbase->get(dbase, &dbkey, &dbdat, 0) == 0 && !IS_NEG(dbdat.data)) {
if (memcmp(dbdat.data, a+1, dbdat.size) == 0)
return;
stats.arp_change++;
} else {
stats.arp_new++;
}
dbdat.data = a+1;
dbdat.size = a->ar_hln;
dbase->put(dbase, &dbkey, &dbdat, 0);
}
static void catch_signal(int sig, void (*handler)(int))
{
struct sigaction sa = { .sa_handler = handler };
#ifdef SA_INTERRUPT
sa.sa_flags = SA_INTERRUPT;
#endif
sigaction(sig, &sa, NULL);
}
#include <setjmp.h>
sigjmp_buf env;
volatile int in_poll;
static void sig_exit(int signo)
{
do_exit = 1;
if (in_poll)
siglongjmp(env, 1);
}
static void sig_sync(int signo)
{
do_sync = 1;
if (in_poll)
siglongjmp(env, 1);
}
static void sig_stats(int signo)
{
do_sync = 1;
do_stats = 1;
if (in_poll)
siglongjmp(env, 1);
}
static void send_stats(void)
{
syslog(LOG_INFO, "arp_rcv: n%lu c%lu app_rcv: tot %lu hits %lu bad %lu neg %lu sup %lu",
stats.arp_new, stats.arp_change,
stats.app_recv, stats.app_success,
stats.app_bad, stats.app_neg, stats.app_suppressed
);
syslog(LOG_INFO, "kern: n%lu c%lu neg %lu arp_send: %lu rlim %lu",
stats.kern_new, stats.kern_change, stats.kern_neg,
stats.probes_sent, stats.probes_suppressed
);
do_stats = 0;
}
int main(int argc, char **argv)
{
int opt;
int do_list = 0;
char *do_load = NULL;
while ((opt = getopt(argc, argv, "h?b:lf:a:n:p:kR:B:")) != EOF) {
switch (opt) {
case 'b':
dbname = optarg;
break;
case 'f':
if (do_load) {
fprintf(stderr, "Duplicate option -f\n");
usage();
}
do_load = optarg;
break;
case 'l':
do_list = 1;
break;
case 'a':
active_probing = atoi(optarg);
break;
case 'n':
negative_timeout = atoi(optarg);
break;
case 'k':
no_kernel_broadcasts = 1;
break;
case 'p':
if ((poll_timeout = 1000 * strtod(optarg, NULL)) < 100) {
fprintf(stderr, "Invalid poll timeout\n");
exit(-1);
}
break;
case 'R':
if ((broadcast_rate = atoi(optarg)) <= 0 ||
(broadcast_rate = 1000/broadcast_rate) <= 0) {
fprintf(stderr, "Invalid ARP rate\n");
exit(-1);
}
break;
case 'B':
if ((broadcast_burst = atoi(optarg)) <= 0 ||
(broadcast_burst = 1000*broadcast_burst) <= 0) {
fprintf(stderr, "Invalid ARP burst\n");
exit(-1);
}
break;
case 'h':
case '?':
default:
usage();
}
}
argc -= optind;
argv += optind;
if (argc > 0) {
ifnum = argc;
ifnames = argv;
ifvec = malloc(argc*sizeof(int));
if (!ifvec) {
perror("malloc");
exit(-1);
}
}
if ((udp_sock = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
perror("socket");
exit(-1);
}
if (ifnum) {
int i;
struct ifreq ifr = {};
for (i = 0; i < ifnum; i++) {
strncpy(ifr.ifr_name, ifnames[i], IFNAMSIZ);
if (ioctl(udp_sock, SIOCGIFINDEX, &ifr)) {
perror("ioctl(SIOCGIFINDEX)");
exit(-1);
}
ifvec[i] = ifr.ifr_ifindex;
}
}
dbase = dbopen(dbname, O_CREAT|O_RDWR, 0644, DB_HASH, NULL);
if (dbase == NULL) {
perror("db_open");
exit(-1);
}
if (do_load) {
char buf[128];
FILE *fp;
struct dbkey k;
DBT dbkey, dbdat;
dbkey.data = &k;
dbkey.size = sizeof(k);
if (strcmp(do_load, "-") == 0 || strcmp(do_load, "--") == 0) {
fp = stdin;
} else if ((fp = fopen(do_load, "r")) == NULL) {
perror("fopen");
goto do_abort;
}
buf[sizeof(buf)-1] = 0;
while (fgets(buf, sizeof(buf), fp)) {
__u8 b1[6];
char ipbuf[128];
char macbuf[128];
if (buf[0] == '#')
continue;
if (sscanf(buf, "%u%s%s", &k.iface, ipbuf, macbuf) != 3) {
fprintf(stderr, "Wrong format of input file \"%s\"\n", do_load);
goto do_abort;
}
if (strncmp(macbuf, "FAILED:", 7) == 0)
continue;
if (!inet_aton(ipbuf, (struct in_addr *)&k.addr)) {
fprintf(stderr, "Invalid IP address: \"%s\"\n", ipbuf);
goto do_abort;
}
if (ll_addr_a2n((char *) b1, 6, macbuf) != 6)
goto do_abort;
dbdat.size = 6;
if (dbase->put(dbase, &dbkey, &dbdat, 0)) {
perror("hash->put");
goto do_abort;
}
}
dbase->sync(dbase, 0);
if (fp != stdin)
fclose(fp);
}
if (do_list) {
DBT dbkey, dbdat;
printf("%-8s %-15s %s\n", "#Ifindex", "IP", "MAC");
while (dbase->seq(dbase, &dbkey, &dbdat, R_NEXT) == 0) {
struct dbkey *key = dbkey.data;
if (handle_if(key->iface)) {
if (!IS_NEG(dbdat.data)) {
char b1[18];
printf("%-8d %-15s %s\n",
key->iface,
inet_ntoa(*(struct in_addr *)&key->addr),
ll_addr_n2a(dbdat.data, 6, ARPHRD_ETHER, b1, 18));
} else {
printf("%-8d %-15s FAILED: %dsec ago\n",
key->iface,
inet_ntoa(*(struct in_addr *)&key->addr),
NEG_AGE(dbdat.data));
}
}
}
}
if (do_load || do_list)
goto out;
pset[0].fd = socket(PF_PACKET, SOCK_DGRAM, 0);
if (pset[0].fd < 0) {
perror("socket");
exit(-1);
}
if (1) {
struct sockaddr_ll sll = {
.sll_family = AF_PACKET,
.sll_protocol = htons(ETH_P_ARP),
.sll_ifindex = (ifnum == 1 ? ifvec[0] : 0),
};
if (bind(pset[0].fd, (struct sockaddr *)&sll, sizeof(sll)) < 0) {
perror("bind");
goto do_abort;
}
}
if (rtnl_open(&rth, RTMGRP_NEIGH) < 0) {
perror("rtnl_open");
goto do_abort;
}
pset[1].fd = rth.fd;
load_initial_table();
if (daemon(0, 0)) {
perror("arpd: daemon");
goto do_abort;
}
openlog("arpd", LOG_PID | LOG_CONS, LOG_DAEMON);
catch_signal(SIGINT, sig_exit);
catch_signal(SIGTERM, sig_exit);
catch_signal(SIGHUP, sig_sync);
catch_signal(SIGUSR1, sig_stats);
#define EVENTS (POLLIN|POLLPRI|POLLERR|POLLHUP)
pset[0].events = EVENTS;
pset[0].revents = 0;
pset[1].events = EVENTS;
pset[1].revents = 0;
sigsetjmp(env, 1);
for (;;) {
in_poll = 1;
if (do_exit)
break;
if (do_sync) {
in_poll = 0;
dbase->sync(dbase, 0);
do_sync = 0;
in_poll = 1;
}
if (do_stats)
send_stats();
if (poll(pset, 2, poll_timeout) > 0) {
in_poll = 0;
if (pset[0].revents&EVENTS)
get_arp_pkt();
if (pset[1].revents&EVENTS)
get_kern_msg();
} else {
do_sync = 1;
}
}
undo_sysctl_adjustments();
out:
dbase->close(dbase);
exit(0);
do_abort:
dbase->close(dbase);
exit(-1);
}