19550-1 (Алгоритми маршрутизації в мережах), страница 3
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Документ из архива "Алгоритми маршрутизації в мережах", который расположен в категории "". Всё это находится в предмете "иностранный язык" из , которые можно найти в файловом архиве . Не смотря на прямую связь этого архива с , его также можно найти и в других разделах. Архив можно найти в разделе "остальное", в предмете "иностранный язык" в общих файлах.
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*
* Start broadcasting after hearing from other routers, and
* at a random time so a bunch of systems do not get synchronized
* after a power failure.
*/
intvl_random(&next_bcast, EPOCH+MIN_WAITTIME, EPOCH+SUPPLY_INTERVAL);
age_timer.tv_usec = next_bcast.tv_usec;
age_timer.tv_sec = EPOCH+MIN_WAITTIME;
rdisc_timer = next_bcast;
ifinit_timer.tv_usec = next_bcast.tv_usec;
/* Collect an initial view of the world by checking the interface
* configuration and the kludge file.
*/
gwkludge();
ifinit();
flush_kern();
/* Ask for routes */
rip_query();
rdisc_sol();
/* Loop forever, listening and broadcasting.
*/
for (;;) {
prev_clk = clk;
gettimeofday(&clk, 0);
timevalsub(&t2, &clk, &prev_clk);
if (t2.tv_sec < 0
|| t2.tv_sec > wtime.tv_sec + 5) {
/* Deal with time changes before other housekeeping to
* keep everything straight.
*/
dt = t2.tv_sec;
if (dt > 0)
dt -= wtime.tv_sec;
trace_act("time changed by %d sec", dt);
epoch.tv_sec += dt;
}
timevalsub(&now, &clk, &epoch);
now_stale = now.tv_sec - STALE_TIME;
now_expire = now.tv_sec - EXPIRE_TIME;
now_garbage = now.tv_sec - GARBAGE_TIME;
/* deal with signals that should affect tracing */
set_tracelevel();
if (stopint != 0) {
rip_bcast(0);
rdisc_adv();
trace_off("exiting with signal %d\n", stopint);
exit(stopint | 128);
}
/* look for new or dead interfaces */
timevalsub(&wtime, &ifinit_timer, &now);
if (wtime.tv_sec <= 0) {
wtime.tv_sec = 0;
ifinit();
rip_query();
continue;
}
/* If it is time, then broadcast our routes.
*/
if (supplier || advertise_mhome) {
timevalsub(&t2, &next_bcast, &now);
if (t2.tv_sec <= 0) {
/* Synchronize the aging and broadcast
* timers to minimize awakenings
*/
age(0);
rip_bcast(0);
/* It is desirable to send routing updates
* regularly. So schedule the next update
* 30 seconds after the previous one was
* secheduled, instead of 30 seconds after
* the previous update was finished.
* Even if we just started after discovering
* a 2nd interface or were otherwise delayed,
* pick a 30-second aniversary of the
* original broadcast time.
*/
n = 1 + (0-t2.tv_sec)/SUPPLY_INTERVAL;
next_bcast.tv_sec += n*SUPPLY_INTERVAL;
continue;
}
if (timercmp(&t2, &wtime, <))
wtime = t2;
}
/* If we need a flash update, either do it now or
* set the delay to end when it is time.
*
* If we are within MIN_WAITTIME seconds of a full update,
* do not bother.
*/
if (need_flash
&& supplier
&& no_flash.tv_sec+MIN_WAITTIME < next_bcast.tv_sec) {
/* accurate to the millisecond */
if (!timercmp(&no_flash, &now, >))
rip_bcast(1);
timevalsub(&t2, &no_flash, &now);
if (timercmp(&t2, &wtime, <))
wtime = t2;
}
/* trigger the main aging timer.
*/
timevalsub(&t2, &age_timer, &now);
if (t2.tv_sec <= 0) {
age(0);
continue;
}
if (timercmp(&t2, &wtime, <))
wtime = t2;
/* update the kernel routing table
*/
timevalsub(&t2, &need_kern, &now);
if (t2.tv_sec <= 0) {
age(0);
continue;
}
if (timercmp(&t2, &wtime, <))
wtime = t2;
/* take care of router discovery,
* but do it to the millisecond
*/
if (!timercmp(&rdisc_timer, &now, >)) {
rdisc_age(0);
continue;
}
timevalsub(&t2, &rdisc_timer, &now);
if (timercmp(&t2, &wtime, <))
wtime = t2;
/* wait for input or a timer to expire.
*/
trace_flush();
ibits = fdbits;
n = select(sock_max, &ibits, 0, 0, &wtime);
if (n <= 0) {
if (n < 0 && errno != EINTR && errno != EAGAIN)
BADERR(1,"select");
continue;
}
if (FD_ISSET(rt_sock, &ibits)) {
read_rt();
n--;
}
if (rdisc_sock >= 0 && FD_ISSET(rdisc_sock, &ibits)) {
read_d();
n--;
}
if (rip_sock >= 0 && FD_ISSET(rip_sock, &ibits)) {
read_rip(rip_sock, 0);
n--;
}
for (ifp = ifnet; n > 0 && 0 != ifp; ifp = ifp->int_next) {
if (ifp->int_rip_sock >= 0
&& FD_ISSET(ifp->int_rip_sock, &ibits)) {
read_rip(ifp->int_rip_sock, ifp);
n--;
}
}
}
}
/* ARGSUSED */
void
sigalrm(int s)
{
/* Historically, SIGALRM would cause the daemon to check for
* new and broken interfaces.
*/
ifinit_timer.tv_sec = now.tv_sec;
trace_act("SIGALRM");
}
/* watch for fatal signals */
void
sigterm(int sig)
{
stopint = sig;
(void)signal(sig, SIG_DFL); /* catch it only once */
}
void
fix_select(void)
{
struct interface *ifp;
FD_ZERO(&fdbits);
sock_max = 0;
FD_SET(rt_sock, &fdbits);
if (sock_max <= rt_sock)
sock_max = rt_sock+1;
if (rip_sock >= 0) {
FD_SET(rip_sock, &fdbits);
if (sock_max <= rip_sock)
sock_max = rip_sock+1;
}
for (ifp = ifnet; 0 != ifp; ifp = ifp->int_next) {
if (ifp->int_rip_sock >= 0) {
FD_SET(ifp->int_rip_sock, &fdbits);
if (sock_max int_rip_sock)
sock_max = ifp->int_rip_sock+1;
}
}
if (rdisc_sock >= 0) {
FD_SET(rdisc_sock, &fdbits);
if (sock_max <= rdisc_sock)
sock_max = rdisc_sock+1;
}
}
void
fix_sock(int sock,
char *name)
{
int on;
#define MIN_SOCKBUF (4*1024)
static int rbuf;
if (fcntl(sock, F_SETFL, O_NONBLOCK) == -1)
logbad(1, "fcntl(%s) O_NONBLOCK: %s",
name, strerror(errno));
on = 1;
if (setsockopt(sock, SOL_SOCKET,SO_BROADCAST, &on,sizeof(on)) < 0)
msglog("setsockopt(%s,SO_BROADCAST): %s",
name, strerror(errno));
#ifdef USE_PASSIFNAME
on = 1;
if (setsockopt(sock, SOL_SOCKET, SO_PASSIFNAME, &on,sizeof(on)) < 0)
msglog("setsockopt(%s,SO_PASSIFNAME): %s",
name, strerror(errno));
#endif
if (rbuf >= MIN_SOCKBUF) {
if (setsockopt(sock, SOL_SOCKET, SO_RCVBUF,
&rbuf, sizeof(rbuf)) < 0)
msglog("setsockopt(%s,SO_RCVBUF=%d): %s",
name, rbuf, strerror(errno));
} else {
for (rbuf = 60*1024; ; rbuf -= 4096) {
if (setsockopt(sock, SOL_SOCKET, SO_RCVBUF,
&rbuf, sizeof(rbuf)) == 0) {
trace_act("RCVBUF=%d", rbuf);
break;
}
if (rbuf < MIN_SOCKBUF) {
msglog("setsockopt(%s,SO_RCVBUF = %d): %s",
name, rbuf, strerror(errno));
break;
}
}
}
}
/* get a rip socket
*/
static int /* <0 or file descriptor */
get_rip_sock(naddr addr,
int serious) /* 1=failure to bind is serious */
{
struct sockaddr_in sin;
unsigned char ttl;
int s;
if ((s = socket(AF_INET, SOCK_DGRAM, 0)) < 0)
BADERR(1,"rip_sock = socket()");
bzero(&sin,sizeof(sin));
#ifdef _HAVE_SIN_LEN
sin.sin_len = sizeof(sin);
#endif
sin.sin_family = AF_INET;
sin.sin_port = htons(RIP_PORT);
sin.sin_addr.s_addr = addr;
if (bind(s, (struct sockaddr *)&sin,sizeof(sin)) < 0) {
if (serious)
BADERR(errno != EADDRINUSE, "bind(rip_sock)");
return -1;
}
fix_sock(s,"rip_sock");
ttl = 1;
if (setsockopt(s, IPPROTO_IP, IP_MULTICAST_TTL,
&ttl, sizeof(ttl)) < 0)
DBGERR(1,"rip_sock setsockopt(IP_MULTICAST_TTL)");
return s;
}
/* turn off main RIP socket */
void
rip_off(void)
{
struct interface *ifp;
register naddr addr;
if (rip_sock >= 0 && !mhome) {
trace_act("turn off RIP");
(void)close(rip_sock);
rip_sock = -1;
/* get non-broadcast sockets to listen to queries.
*/
for (ifp = ifnet; ifp != 0; ifp = ifp->int_next) {
if (ifp->int_state & IS_REMOTE)
continue;
if (ifp->int_rip_sock < 0) {
addr = ((ifp->int_if_flags & IFF_POINTOPOINT)
? ifp->int_dstaddr
: ifp->int_addr);
ifp->int_rip_sock = get_rip_sock(addr, 0);
}
}
fix_select();
age(0);
}
}
/* turn on RIP multicast input via an interface
*/
static void
rip_mcast_on(struct interface *ifp)
{
struct ip_mreq m;
if (!IS_RIP_IN_OFF(ifp->int_state)
&& (ifp->int_if_flags & IFF_MULTICAST)
#ifdef MCAST_PPP_BUG
&& !(ifp->int_if_flags & IFF_POINTOPOINT)
#endif
&& !(ifp->int_state & IS_ALIAS)) {
m.imr_multiaddr.s_addr = htonl(INADDR_RIP_GROUP);
m.imr_interface.s_addr = ((ifp->int_if_flags & IFF_POINTOPOINT)
? ifp->int_dstaddr
: ifp->int_addr);
if (setsockopt(rip_sock,IPPROTO_IP, IP_ADD_MEMBERSHIP,
&m, sizeof(m)) < 0)
LOGERR("setsockopt(IP_ADD_MEMBERSHIP RIP)");
}
}
/* Prepare socket used for RIP.
*/
void
rip_on(struct interface *ifp)
{
/* If the main RIP socket is already alive, only start receiving
* multicasts for this interface.
*/
if (rip_sock >= 0) {
if (ifp != 0)
rip_mcast_on(ifp);
return;
}
/* If the main RIP socket is off and it makes sense to turn it on,
* then turn it on for all of the interfaces.
*/
if (rip_interfaces > 0 && !rdisc_ok) {
trace_act("turn on RIP");
/* Close all of the query sockets so that we can open
* the main socket. SO_REUSEPORT is not a solution,
* since that would let two daemons bind to the broadcast
* socket.
*/
for (ifp = ifnet; ifp != 0; ifp = ifp->int_next) {
if (ifp->int_rip_sock >= 0) {
(void)close(ifp->int_rip_sock);
ifp->int_rip_sock = -1;
}
}
rip_sock = get_rip_sock(INADDR_ANY, 1);
rip_sock_mcast = 0;
/* Do not advertise anything until we have heard something
*/
if (next_bcast.tv_sec < now.tv_sec+MIN_WAITTIME)
next_bcast.tv_sec = now.tv_sec+MIN_WAITTIME;
for (ifp = ifnet; ifp != 0; ifp = ifp->int_next) {
ifp->int_query_time = NEVER;
rip_mcast_on(ifp);
}
ifinit_timer.tv_sec = now.tv_sec;
} else if (ifp != 0
&& !(ifp->int_state & IS_REMOTE)
&& ifp->int_rip_sock < 0) {
/* RIP is off, so ensure there are sockets on which
* to listen for queries.
*/
ifp->int_rip_sock = get_rip_sock(ifp->int_addr, 0);
}
fix_select();
}
/* die if malloc(3) fails
*/
void *
rtmalloc(size_t size,
char *msg)
{
void *p = malloc(size);
if (p == 0)
logbad(1,"malloc() failed in %s", msg);
return p;
}
/* get a random instant in an interval
*/
void
intvl_random(struct timeval *tp, /* put value here */
u_long lo, /* value is after this second */
u_long hi) /* and before this */
{
tp->tv_sec = (time_t)(hi == lo
? lo
: (lo + random() % ((hi - lo))));
tp->tv_usec = random() % 1000000;
}
void
timevaladd(struct timeval *t1,
struct timeval *t2)
{
t1->tv_sec += t2->tv_sec;
if ((t1->tv_usec += t2->tv_usec) > 1000000) {
t1->tv_sec++;
t1->tv_usec -= 1000000;
}
}
/* t1 = t2 - t3
*/
static void
timevalsub(struct timeval *t1,
struct timeval *t2,
struct timeval *t3)
{
t1->tv_sec = t2->tv_sec - t3->tv_sec;
if ((t1->tv_usec = t2->tv_usec - t3->tv_usec) < 0) {
t1->tv_sec--;
t1->tv_usec += 1000000;
}
}
/* put a message into the system log
*/
void
msglog(char *p, ...)
{
va_list args;
trace_flush();
va_start(args, p);
vsyslog(LOG_ERR, p, args);
if (ftrace != 0) {
if (ftrace == stdout)
(void)fputs("routed: ", ftrace);
(void)vfprintf(ftrace, p, args);
(void)fputc('\n', ftrace);
}
}
/* Put a message about a bad system into the system log if
* we have not complained about it recently.
*
* It is desirable to complain about all bad systems, but not too often.
* In the worst case, it is not practical to keep track of all bad systems.
* For example, there can be many systems with the wrong password.
*/
void
msglim(struct msg_limit *lim, naddr addr, char *p, ...)
{
va_list args;
int i;
struct msg_sub *ms1, *ms;
char *p1;
va_start(args, p);
/* look for the oldest slot in the table
* or the slot for the bad router.
*/
ms = ms1 = lim->subs;
for (i = MSG_SUBJECT_N; ; i--, ms1++) {
if (i == 0) {
/* Reuse a slot at most once every 10 minutes.
*/
if (lim->reuse > now.tv_sec) {
ms = 0;
} else {
ms = ms1;
lim->reuse = now.tv_sec + 10*60;
}
break;
}
if (ms->addr == addr) {
/* Repeat a complaint about a given system at
* most once an hour.
*/
if (ms->until > now.tv_sec)
ms = 0;
break;
}
if (ms->until until)
ms = ms1;
}
if (ms != 0) {
ms->addr = addr;
ms->until = now.tv_sec + 60*60; /* 60 minutes */
trace_flush();
for (p1 = p; *p1 == ' '; p1++)
continue;
vsyslog(LOG_ERR, p1, args);
}
/* always display the message if tracing */
if (ftrace != 0) {
(void)vfprintf(ftrace, p, args);
(void)fputc('\n', ftrace);
}
}
void
logbad(int dump, char *p, ...)
{
va_list args;
trace_flush();
va_start(args, p);
vsyslog(LOG_ERR, p, args);
(void)fputs("routed: ", stderr);
(void)vfprintf(stderr, p, args);
(void)fputs("; giving up\n",stderr);
(void)fflush(stderr);
if (dump)
abort();
exit(1);
}
Список литературы
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