minix/commands/irdpd/irdpd.c
2010-05-12 16:28:54 +00:00

624 lines
15 KiB
C

/* irdpd 1.10 - Internet router discovery protocol daemon.
* Author: Kees J. Bot
* 28 May 1994
* Activily solicitate or passively look for routers.
* Based heavily on its forerunners, the irdp_sol and rip2icmp daemons by
* Philip Homburg.
*/
#define nil 0
#include <sys/types.h>
#include <errno.h>
#include <fcntl.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <limits.h>
#include <unistd.h>
#include <signal.h>
#include <sys/ioctl.h>
#include <sys/asynchio.h>
#include <net/hton.h>
#include <net/netlib.h>
#include <net/gen/in.h>
#include <net/gen/ip_hdr.h>
#include <net/gen/icmp.h>
#include <net/gen/icmp_hdr.h>
#include <net/gen/ip_io.h>
#include <net/gen/inet.h>
#include <net/gen/netdb.h>
#include <net/gen/oneCsum.h>
#include <net/gen/socket.h>
#include <net/gen/udp.h>
#include <net/gen/udp_hdr.h>
#include <net/gen/udp_io.h>
#define MAX_SOLICITATIONS 3 /* # router solicitations. */
#define SOLICITATION_INTERVAL 3 /* Secs between solicitate retries. */
#define DEST_TO (10*60) /* 10 minutes */
#define NEW_ROUTE (5*60) /* 5 minutes */
#define DANGER (2*60) /* Nearing a advert timeout? */
#define DEAD_TO (24L*60*60) /* 24 hours */
#define DEAD_PREF 0x80000000L /* From RFC 1256 */
#define MaxAdvertisementInterval (DEST_TO/2) /* Chosen to jive with RIP */
#define AdvertisementLifetime DEST_TO
#define PRIO_OFF_DEF -1024
#define RIP_REPLY 2
/* It's now or never. */
#define IMMEDIATELY ((time_t) ((time_t) -1 < 0 ? LONG_MIN : 0))
#define NEVER ((time_t) ((time_t) -1 < 0 ? LONG_MAX : ULONG_MAX))
#if !__minix_vmd
/* Standard Minix needs to choose between router discovery and RIP info. */
int do_rdisc= 1;
int do_rip= 0;
#else
/* VMD Minix can do both at once. */
#define do_rdisc 1
#define do_rip 1
#endif
int rip_fd; /* For incoming RIP packet. */
int irdp_fd; /* Receive or transmit IRDP packets. */
char *udp_device; /* UDP device to use. */
char *ip_device; /* IP device to use. */
int priority_offset; /* Offset to make my routes less preferred. */
int bcast= 0; /* Broadcast adverts to all. */
int debug= 0;
char rip_buf[8192]; /* Incoming RIP packet buffer. */
char irdp_buf[1024]; /* IRDP buffer. */
typedef struct routeinfo
{
u8_t command;
u8_t version;
u16_t zero1;
struct routedata {
u16_t family;
u16_t zero2;
u32_t ip_addr;
u32_t zero3, zero4;
u32_t metric;
} data[1];
} routeinfo_t;
typedef struct table
{
ipaddr_t tab_gw;
i32_t tab_pref;
time_t tab_time;
} table_t;
table_t *table; /* Collected table of routing info. */
size_t table_size;
int sol_retries= MAX_SOLICITATIONS;
time_t next_sol= IMMEDIATELY;
time_t next_advert= NEVER;
time_t router_advert_valid= IMMEDIATELY;
time_t now;
void report(const char *label)
/* irdpd: /dev/hd0: Device went up in flames */
{
fprintf(stderr, "irdpd: %s: %s\n", label, strerror(errno));
}
void fatal(const char *label)
/* irdpd: /dev/house: Taking this with it */
{
report(label);
exit(1);
}
#if DEBUG
char *addr2name(ipaddr_t host)
/* Translate an IP address to a printable name. */
{
struct hostent *hostent;
hostent= gethostbyaddr((char *) &host, sizeof(host), AF_INET);
return hostent == nil ? inet_ntoa(host) : hostent->h_name;
}
#else
#define addr2name(host) inet_ntoa(host)
#endif
void print_table(void)
/* Show the collected routing table. */
{
int i;
table_t *ptab;
struct tm *tm;
for (i= 0, ptab= table; i < table_size; i++, ptab++) {
if (ptab->tab_time < now - DEAD_TO) continue;
tm= localtime(&ptab->tab_time);
printf("%-40s %6ld %02d:%02d:%02d\n",
addr2name(ptab->tab_gw),
(long) ptab->tab_pref,
tm->tm_hour, tm->tm_min, tm->tm_sec);
}
}
void advertize(ipaddr_t host)
/* Send a router advert to a host. */
{
char *buf, *data;
ip_hdr_t *ip_hdr;
icmp_hdr_t *icmp_hdr;
int i;
table_t *ptab;
buf= malloc(sizeof(*ip_hdr) + offsetof(icmp_hdr_t, ih_dun.uhd_data)
+ table_size * (sizeof(ipaddr_t) + sizeof(u32_t)));
if (buf == nil) fatal("heap error");
ip_hdr= (ip_hdr_t *) buf;
icmp_hdr= (icmp_hdr_t *) (ip_hdr + 1);
ip_hdr->ih_vers_ihl= 0x45;
ip_hdr->ih_dst= host;
icmp_hdr->ih_type= ICMP_TYPE_ROUTER_ADVER;
icmp_hdr->ih_code= 0;
icmp_hdr->ih_hun.ihh_ram.iram_na= 0;
icmp_hdr->ih_hun.ihh_ram.iram_aes= 2;
icmp_hdr->ih_hun.ihh_ram.iram_lt= htons(AdvertisementLifetime);
data= (char *) icmp_hdr->ih_dun.uhd_data;
/* Collect gateway entries from the table. */
for (i= 0, ptab= table; i < table_size; i++, ptab++) {
if (ptab->tab_time < now - DEAD_TO) continue;
icmp_hdr->ih_hun.ihh_ram.iram_na++;
if (ptab->tab_time < now - DEST_TO) ptab->tab_pref= DEAD_PREF;
* (ipaddr_t *) data= ptab->tab_gw;
data+= sizeof(ipaddr_t);
* (i32_t *) data= htonl(ptab->tab_pref);
data+= sizeof(i32_t);
}
icmp_hdr->ih_chksum= 0;
icmp_hdr->ih_chksum= ~oneC_sum(0, icmp_hdr, data - (char *) icmp_hdr);
if (icmp_hdr->ih_hun.ihh_ram.iram_na > 0) {
/* Send routing info. */
if (debug) {
printf("Routing table send to %s:\n", addr2name(host));
print_table();
}
if (write(irdp_fd, buf, data - buf) < 0) {
(errno == EIO ? fatal : report)(ip_device);
}
}
free(buf);
}
void time_functions(void)
/* Perform time dependend functions: router solicitation, router advert. */
{
if (now >= next_sol) {
char buf[sizeof(ip_hdr_t) + 8];
ip_hdr_t *ip_hdr;
icmp_hdr_t *icmp_hdr;
if (sol_retries == 0) {
/* Stop soliciting. */
next_sol= NEVER;
#if !__minix_vmd
/* Switch to RIP if no router responded. */
if (table_size == 0) {
do_rip= 1;
do_rdisc= 0;
}
#endif
return;
}
/* Broadcast a router solicitation to find a router. */
ip_hdr= (ip_hdr_t *) buf;
icmp_hdr= (icmp_hdr_t *) (ip_hdr + 1);
ip_hdr->ih_vers_ihl= 0x45;
ip_hdr->ih_dst= HTONL(0xFFFFFFFFL);
icmp_hdr->ih_type= ICMP_TYPE_ROUTE_SOL;
icmp_hdr->ih_code= 0;
icmp_hdr->ih_chksum= 0;
icmp_hdr->ih_hun.ihh_unused= 0;
icmp_hdr->ih_chksum= ~oneC_sum(0, icmp_hdr, 8);
if (debug) printf("Broadcasting router solicitation\n");
if (write(irdp_fd, buf, sizeof(buf)) < 0)
fatal("sending router solicitation failed");
/* Schedule the next packet. */
next_sol= now + SOLICITATION_INTERVAL;
sol_retries--;
}
if (now >= next_advert) {
/* Advertize routes to the local host (normally), or
* broadcast them (to keep bad hosts up.)
*/
advertize(bcast ? HTONL(0xFFFFFFFFL) : HTONL(0x7F000001L));
next_advert= now + MaxAdvertisementInterval;
#if !__minix_vmd
/* Make sure we are listening to RIP now. */
do_rip= 1;
do_rdisc= 0;
#endif
}
}
void add_gateway(ipaddr_t host, i32_t pref)
/* Add a router with given address and preference to the routing table. */
{
table_t *oldest, *ptab;
int i;
/* Look for the host, or select the oldest entry. */
oldest= nil;
for (i= 0, ptab= table; i < table_size; i++, ptab++) {
if (ptab->tab_gw == host) break;
if (oldest == nil || ptab->tab_time < oldest->tab_time)
oldest= ptab;
}
/* Don't evict the oldest if it is still valid. */
if (oldest != nil && oldest->tab_time >= now - DEST_TO) oldest= nil;
/* Expand the table? */
if (i == table_size && oldest == nil) {
table_size++;
table= realloc(table, table_size * sizeof(*table));
if (table == nil) fatal("heap error");
oldest= &table[table_size - 1];
}
if (oldest != nil) {
ptab= oldest;
ptab->tab_gw= host;
ptab->tab_pref= DEAD_PREF;
}
/* Replace an entry if the new one looks more promising. */
if (pref >= ptab->tab_pref || ptab->tab_time <= now - NEW_ROUTE) {
ptab->tab_pref= pref;
ptab->tab_time= now;
}
}
void rip_incoming(ssize_t n)
/* Use a RIP packet to add to the router table. (RIP packets are really for
* between routers, but often it is the only information around.)
*/
{
udp_io_hdr_t *udp_io_hdr;
u32_t default_dist;
i32_t pref;
routeinfo_t *routeinfo;
struct routedata *data, *end;
/* We don't care about RIP packets when there are router adverts. */
if (now + MaxAdvertisementInterval < router_advert_valid) return;
udp_io_hdr= (udp_io_hdr_t *) rip_buf;
if (udp_io_hdr->uih_data_len != n - sizeof(*udp_io_hdr)) {
if (debug) printf("Bad sized route packet (discarded)\n");
return;
}
routeinfo= (routeinfo_t *) (rip_buf + sizeof(*udp_io_hdr)
+ udp_io_hdr->uih_ip_opt_len);
if (routeinfo->command != RIP_REPLY) {
if (debug) {
printf("RIP-%d packet command %d ignored\n",
routeinfo->version, routeinfo->command);
}
return;
}
/* Look for a default route, the route to the gateway. */
end= (struct routedata *) (rip_buf + n);
default_dist= (u32_t) -1;
for (data= routeinfo->data; data < end; data++) {
if (ntohs(data->family) != AF_INET || data->ip_addr != 0)
continue;
default_dist= ntohl(data->metric);
if (default_dist >= 256) {
if (debug) {
printf("Strange metric %lu\n",
(unsigned long) default_dist);
}
}
}
pref= default_dist >= 256 ? 1 : 512 - default_dist;
pref+= priority_offset;
/* Add the gateway to the table with the calculated preference. */
add_gateway(udp_io_hdr->uih_src_addr, pref);
if (debug) {
printf("Routing table after RIP-%d packet from %s:\n",
routeinfo->version,
addr2name(udp_io_hdr->uih_src_addr));
print_table();
}
/* Start advertizing. */
if (next_advert == NEVER) next_advert= IMMEDIATELY;
}
void irdp_incoming(ssize_t n)
/* Look for router solicitations and router advertisements. The solicitations
* are probably from other irdpd daemons, we answer them if we do not expect
* a real router to answer. The advertisements cause this daemon to shut up.
*/
{
ip_hdr_t *ip_hdr;
icmp_hdr_t *icmp_hdr;
int ip_hdr_len;
char *data;
int i;
int router;
ipaddr_t addr;
i32_t pref;
time_t valid;
ip_hdr= (ip_hdr_t *) irdp_buf;
ip_hdr_len= (ip_hdr->ih_vers_ihl & IH_IHL_MASK) << 2;
if (n < ip_hdr_len + 8) {
if (debug) printf("Bad sized ICMP (discarded)\n");
return;
}
icmp_hdr= (icmp_hdr_t *)(irdp_buf + ip_hdr_len);
/* Did I send this myself? */
if (ip_hdr->ih_src == ip_hdr->ih_dst) return;
if ((htonl(ip_hdr->ih_src) & 0xFF000000L) == 0x7F000000L) return;
if (icmp_hdr->ih_type != ICMP_TYPE_ROUTER_ADVER) return;
/* Incoming router advertisement, the kind of packet the TCP/IP task
* is very happy with. No need to solicit further.
*/
sol_retries= 0;
/* Add router info to our table. Also see if the packet really came
* from a router. If so then we can go dormant for the lifetime of
* the ICMP.
*/
router= 0;
data= (char *) icmp_hdr->ih_dun.uhd_data;
for (i= 0; i < icmp_hdr->ih_hun.ihh_ram.iram_na; i++) {
addr= * (ipaddr_t *) data;
data+= sizeof(ipaddr_t);
pref= htonl(* (i32_t *) data);
data+= sizeof(i32_t);
if (addr == ip_hdr->ih_src) {
/* The sender is in the routing table! */
router= 1;
}
add_gateway(addr, pref);
}
valid= now + ntohs(icmp_hdr->ih_hun.ihh_ram.iram_lt);
if (router) router_advert_valid= valid;
/* Restart advertizing close to the timeout of the advert. (No more
* irdpd adverts if the router stays alive.)
*/
if (router || next_advert > valid - DANGER)
next_advert= valid - DANGER;
if (debug) {
printf("Routing table after advert received from %s:\n",
addr2name(ip_hdr->ih_src));
print_table();
if (router) {
struct tm *tm= localtime(&router_advert_valid);
printf(
"This router advert is valid until %02d:%02d:%02d\n",
tm->tm_hour, tm->tm_min, tm->tm_sec);
}
}
}
void sig_handler(int sig)
/* A signal changes the debug level. */
{
switch (sig) {
case SIGUSR1: debug++; break;
case SIGUSR2: debug= 0; break;
}
}
void usage(void)
{
fprintf(stderr,
"Usage: irdpd [-bd] [-U udp-device] [-I ip-device] [-o priority-offset]\n");
exit(1);
}
int main(int argc, char **argv)
{
int i;
struct servent *service;
udpport_t route_port;
nwio_udpopt_t udpopt;
nwio_ipopt_t ipopt;
asynchio_t asyn;
time_t timeout;
struct timeval tv;
struct sigaction sa;
char *offset_arg, *offset_end;
long arg;
udp_device= ip_device= nil;
offset_arg= nil;
for (i = 1; i < argc && argv[i][0] == '-'; i++) {
char *p= argv[i] + 1;
if (p[0] == '-' && p[1] == 0) { i++; break; }
while (*p != 0) {
switch (*p++) {
case 'U':
if (udp_device != nil) usage();
if (*p == 0) {
if (++i == argc) usage();
p= argv[i];
}
udp_device= p;
p= "";
break;
case 'I':
if (ip_device != nil) usage();
if (*p == 0) {
if (++i == argc) usage();
p= argv[i];
}
ip_device= p;
p= "";
break;
case 'o':
if (offset_arg != nil) usage();
if (*p == 0) {
if (++i == argc) usage();
p= argv[i];
}
offset_arg= p;
p= "";
break;
case 'b':
bcast= 1;
break;
case 's':
/*obsolete*/
break;
case 'd':
debug= 1;
break;
default:
usage();
}
}
}
if (i != argc) usage();
/* Debug level signals. */
sa.sa_handler= sig_handler;
sigemptyset(&sa.sa_mask);
sa.sa_flags= 0;
sigaction(SIGUSR1, &sa, nil);
sigaction(SIGUSR2, &sa, nil);
if (udp_device == nil && (udp_device= getenv("UDP_DEVICE")) == nil)
udp_device= UDP_DEVICE;
if (ip_device == nil && (ip_device= getenv("IP_DEVICE")) == nil)
ip_device= IP_DEVICE;
if (offset_arg == nil) {
priority_offset= PRIO_OFF_DEF;
} else {
arg= strtol(offset_arg, &offset_end, 0);
if (*offset_end != 0 || (priority_offset= arg) != arg) usage();
}
if ((service= getservbyname("route", "udp")) == nil) {
fprintf(stderr,
"irdpd: unable to look up the port number for the 'route' service\n");
exit(1);
}
route_port= (udpport_t) service->s_port;
if ((rip_fd= open(udp_device, O_RDWR)) < 0) fatal(udp_device);
udpopt.nwuo_flags= NWUO_COPY | NWUO_LP_SET | NWUO_DI_LOC
| NWUO_EN_BROAD | NWUO_RP_SET | NWUO_RA_ANY | NWUO_RWDATALL
| NWUO_DI_IPOPT;
udpopt.nwuo_locport= route_port;
udpopt.nwuo_remport= route_port;
if (ioctl(rip_fd, NWIOSUDPOPT, &udpopt) < 0)
fatal("setting UDP options failed");
if ((irdp_fd= open(ip_device, O_RDWR)) < 0) fatal(ip_device);
ipopt.nwio_flags= NWIO_COPY | NWIO_EN_LOC | NWIO_EN_BROAD
| NWIO_REMANY | NWIO_PROTOSPEC
| NWIO_HDR_O_SPEC | NWIO_RWDATALL;
ipopt.nwio_tos= 0;
ipopt.nwio_ttl= 1;
ipopt.nwio_df= 0;
ipopt.nwio_hdropt.iho_opt_siz= 0;
ipopt.nwio_rem= HTONL(0xFFFFFFFFL);
ipopt.nwio_proto= IPPROTO_ICMP;
if (ioctl(irdp_fd, NWIOSIPOPT, &ipopt) < 0)
fatal("can't configure ICMP channel");
asyn_init(&asyn);
while (1) {
ssize_t r;
if (do_rip) {
/* Try a RIP read. */
r= asyn_read(&asyn, rip_fd, rip_buf, sizeof(rip_buf));
if (r < 0) {
if (errno == EIO) fatal(udp_device);
if (errno != EINPROGRESS) report(udp_device);
} else {
now= time(nil);
rip_incoming(r);
}
}
if (do_rdisc) {
/* Try an IRDP read. */
r= asyn_read(&asyn, irdp_fd, irdp_buf,
sizeof(irdp_buf));
if (r < 0) {
if (errno == EIO) fatal(ip_device);
if (errno != EINPROGRESS) report(ip_device);
} else {
now= time(nil);
irdp_incoming(r);
}
}
fflush(stdout);
/* Compute the next wakeup call. */
timeout= next_sol < next_advert ? next_sol : next_advert;
/* Wait for a RIP or IRDP packet or a timeout. */
tv.tv_sec= timeout;
tv.tv_usec= 0;
if (asyn_wait(&asyn, 0, timeout == NEVER ? nil : &tv) < 0) {
/* Timeout? */
if (errno != EINTR && errno != EAGAIN)
fatal("asyn_wait()");
now= time(nil);
time_functions();
}
}
}