ref: d916a4c3823f55227ffae35738c2497256e307b5
dir: /appl/cmd/ip/rip.b/
implement Rip;
# basic RIP implementation
# understands v2, sends v1
include "sys.m";
sys: Sys;
include "draw.m";
include "bufio.m";
bufio: Bufio;
Iobuf: import bufio;
include "daytime.m";
daytime: Daytime;
include "dial.m";
dial: Dial;
include "ip.m";
ip: IP;
IPaddr, Ifcaddr, Udphdr: import ip;
include "attrdb.m";
attrdb: Attrdb;
include "arg.m";
Rip: module
{
init: fn(nil: ref Draw->Context, nil: list of string);
};
# rip header:
# op[1] version[1] pad[2]
Oop: con 0; # op: byte
Oversion: con 1; # version: byte
Opad: con 2; # 2 byte pad
Riphdrlen: con Opad+2; # op[1] version[1] mbz[2]
# rip route entry:
# type[2] tag[2] addr[4] mask[4] nexthop[4] metric[4]
Otype: con 0; # type[2]
Otag: con Otype+2; # tag[2] v2 or mbz v1
Oaddr: con Otag+2; # addr[4]
Omask: con Oaddr+4; # mask[4] v2 or mbz v1
Onexthop: con Omask+4;
Ometric: con Onexthop+4; # metric[4]
Ipdestlen: con Ometric+4;
Maxripmsg: con 512;
# operations
OpRequest: con 1; # want route
OpReply: con 2; # all or part of route table
HopLimit: con 16; # defined by protocol as `infinity'
RoutesInPkt: con 25; # limit defined by protocol
RIPport: con 520;
Expired: con 180;
Discard: con 240;
OutputRate: con 60; # seconds between routing table transmissions
NetworkCost: con 1; # assume the simple case
Gateway: adt {
dest: IPaddr;
mask: IPaddr;
gateway: IPaddr;
metric: int;
valid: int;
changed: int;
local: int;
time: int;
contains: fn(g: self ref Gateway, a: IPaddr): int;
};
netfd: ref Sys->FD;
routefd: ref Sys->FD;
AF_INET: con 2;
routes: array of ref Gateway;
Routeinc: con 50;
defroute: ref Gateway;
debug := 0;
nochange := 0;
quiet := 1;
myversion := 1; # default protocol version
logfile := "iproute";
netdir := "/net";
now: int;
nets: list of ref Ifcaddr;
addrs: list of IPaddr;
syslog(nil: int, nil: string, s: string)
{
sys->print("rip: %s\n", s);
}
init(nil: ref Draw->Context, args: list of string)
{
sys = load Sys Sys->PATH;
bufio = load Bufio Bufio->PATH;
daytime = load Daytime Daytime->PATH;
dial = load Dial Dial->PATH;
ip = load IP IP->PATH;
ip->init();
arg := load Arg Arg->PATH;
arg->init(args);
arg->setusage("ip/rip [-d] [-r]");
while((o := arg->opt()) != 0)
case o {
'd' => debug++;
'b' => quiet = 0;
'2' => myversion = 2;
'n' => nochange = 1;
'x' => netdir = arg->earg();
* => arg->usage();
}
args = arg->argv();
if(args != nil)
quiet = 0;
for(; args != nil; args = tl args){
(ok, a) := IPaddr.parse(hd args);
if(ok < 0)
fatal(sys->sprint("invalid address: %s", hd args));
addrs = a :: addrs;
}
arg = nil;
sys->pctl(Sys->NEWPGRP|Sys->FORKFD|Sys->FORKNS, nil);
whereami();
addlocal();
routefd = sys->open(sys->sprint("%s/iproute", netdir), Sys->ORDWR);
if(routefd == nil)
fatal(sys->sprint("can't open %s/iproute: %r", netdir));
readroutes();
syslog(0, logfile, "started");
netfd = riplisten();
# broadcast request for all routes
if(!quiet){
sendall(OpRequest, 0);
spawn sender();
}
# read routing requests
buf := array[8192] of byte;
while((nb := sys->read(netfd, buf, len buf)) > 0){
nb -= Riphdrlen + IP->Udphdrlen;
if(nb < 0)
continue;
uh := Udphdr.unpack(buf, IP->Udphdrlen);
hdr := buf[IP->Udphdrlen:];
version := int hdr[Oversion];
if(version < 1)
continue;
bp := buf[IP->Udphdrlen + Riphdrlen:];
case int hdr[Oop] {
OpRequest =>
# TO DO: transmit in response to request? only if something interesting to say...
;
OpReply =>
# wrong source port?
if(uh.rport != RIPport)
continue;
# my own broadcast?
if(ismyaddr(uh.raddr))
continue;
now = daytime->now();
if(debug > 1)
sys->fprint(sys->fildes(2), "from %s:\n", uh.raddr.text());
for(; (nb -= Ipdestlen) >= 0; bp = bp[Ipdestlen:])
unpackroute(bp, version, uh.raddr);
* =>
if(debug)
sys->print("rip: unexpected op: %d\n", int hdr[Oop]);
}
}
}
whereami()
{
for(ifcs := ip->readipifc(netdir, -1).t0; ifcs != nil; ifcs = tl ifcs)
for(al := (hd ifcs).addrs; al != nil; al = tl al){
ifa := hd al;
if(!ifa.ip.isv4())
continue;
# how to tell broadcast? must be told? actually, it's in /net/iproute
nets = ifa :: nets;
}
}
ismyaddr(a: IPaddr): int
{
for(l := nets; l != nil; l = tl l)
if((hd l).ip.eq(a))
return 1;
return 0;
}
addlocal()
{
for(l := nets; l != nil; l = tl l){
ifc := hd l;
g := lookup(ifc.net);
g.valid = 1;
g.local = 1;
g.gateway = ifc.ip;
g.mask = ifc.mask;
g.metric = NetworkCost;
g.time = 0;
g.changed = 1;
if(debug)
syslog(0, logfile, sys->sprint("Existing: %s & %s -> %s", g.dest.text(), g.mask.masktext(), g.gateway.text()));
}
}
#
# record any existing routes
#
readroutes()
{
now = daytime->now();
b := bufio->fopen(routefd, Sys->OREAD);
while((l := b.gets('\n')) != nil){
(nf, flds) := sys->tokenize(l, " \t");
if(nf >= 5){
flags := hd tl tl tl flds;
if(flags == nil || flags[0] != '4' || contains(flags, "ibum"))
continue;
g := lookup(parseip(hd flds));
g.mask = parsemask(hd tl flds);
g.gateway = parseip(hd tl tl flds);
g.metric = HopLimit;
g.time = now;
g.changed = 1;
if(debug)
syslog(0, logfile, sys->sprint("Existing: %s & %s -> %s", g.dest.text(), g.mask.masktext(), g.gateway.text()));
if(iszero(g.dest) && iszero(g.mask)){
defroute = g;
g.local = 1;
}else if(defroute != nil && g.dest.eq(defroute.gateway))
continue;
else
g.local = !ismyaddr(g.gateway);
}
}
}
unpackroute(b: array of byte, version: int, gwa: IPaddr)
{
# check that it's an IP route, valid metric, MBZ fields zero
if(b[0] != byte 0 || b[1] != byte AF_INET){
if(debug > 1)
sys->fprint(sys->fildes(2), "\t-- unknown address type %x,%x\n", int b[0], int b[1]);
return;
}
dest := IPaddr.newv4(b[Oaddr:]);
mask: IPaddr;
if(version == 1){
# check MBZ fields
if(ip->get2(b, 2) | ip->get4(b, Omask) | ip->get4(b, Onexthop)){
if(debug > 1)
sys->fprint(sys->fildes(2), "\t-- non-zero MBZ\n");
return;
}
mask = maskgen(dest);
}else if(version == 2){
if(ip->get4(b, Omask))
mask = IPaddr.newv4(b[Omask:]);
else
mask = maskgen(dest);
if(ip->get4(b, Onexthop))
gwa = IPaddr.newv4(b[Onexthop:]);
}
metric := ip->get4(b, Ometric);
if(debug > 1)
sys->fprint(sys->fildes(2), "\t%s %d\n", dest.text(), metric);
if(metric <= 0 || metric > HopLimit)
return;
# 1058/3.4.2: response processing
# ignore route if IP address is:
# class D or E
# net 0 (except perhaps 0.0.0.0)
# net 127
# broadcast address (all 1s host part)
# we allow host routes
if(dest.ismulticast() || dest.a[0] == byte 0 || dest.a[0] == byte 16r7F){
if(debug > 1)
sys->fprint(sys->fildes(2), "\t%s %d invalid addr\n", dest.text(), metric);
return;
}
if(isbroadcast(dest, mask)){
if(debug > 1)
sys->fprint(sys->fildes(2), "\t%s & %s -> broadcast\n", dest.text(), mask.masktext());
return;
}
# update the metric min(metric+NetworkCost, HopLimit)
metric += NetworkCost;
if(metric > HopLimit)
metric = HopLimit;
updateroute(dest, mask, gwa, metric);
}
updateroute(dest, mask, gwa: IPaddr, metric: int)
{
# RFC1058 rules page 27-28, with optional replacement of expiring routes
r := lookup(dest);
if(r.valid){
if(r.local)
return; # local, don't touch
if(r.gateway.eq(gwa)){
if(metric != HopLimit){
r.metric = metric;
r.time = now;
}else{
# metric == HopLimit
if(r.metric != HopLimit){
r.metric = metric;
r.changed = 1;
r.time = now - (Discard-120);
delroute(r); # don't use it for routing
# route remains valid but advertised with metric HopLimit
} else if(now >= r.time+Discard){
delroute(r); # finally dead
r.valid = 0;
r.changed = 1;
}
}
}else if(metric < r.metric ||
metric != HopLimit && metric == r.metric && now > r.time+Expired/2){
delroute(r);
r.metric = metric;
r.gateway = gwa;
r.time = now;
addroute(r);
}
} else if(metric < HopLimit){ # new entry
# 1058/3.4.2: don't add route-to-host if host is on net/subnet
# for which we have at least as good a route
if(!mask.eq(ip->allbits) ||
((pr := findroute(dest)) == nil || metric <= pr.metric)){
r.valid = 1;
r.changed = 1;
r.time = now;
r.metric = metric;
r.dest = dest;
r.mask = mask;
r.gateway = gwa;
addroute(r);
}
}
}
sender()
{
for(;;){
sys->sleep(OutputRate*1000); # could add some random fizz
sendall(OpReply, 1);
}
}
onlist(a: IPaddr, l: list of IPaddr): int
{
for(; l != nil; l = tl l)
if(a.eq(hd l))
return 1;
return 0;
}
sendall(op: int, changes: int)
{
for(l := nets; l != nil; l = tl l){
if(addrs != nil && !onlist((hd l).net, addrs))
continue;
a := (hd l).net.copy();
b := (ip->allbits).maskn((hd l).mask);
for(i := 0; i < len a.a; i++)
a.a[i] |= b.a[i];
sendroutes(hd l, a, op, changes);
}
for(i := 0; i < len routes; i++)
if((r := routes[i]) != nil)
r.changed = 0;
}
zeroentry := array[Ipdestlen] of {* => byte 0};
sendroutes(ifc: ref Ifcaddr, dst: IPaddr, op: int, changes: int)
{
if(debug > 1)
sys->print("rip: send %s\n", dst.text());
buf := array[Maxripmsg+IP->Udphdrlen] of byte;
hdr := Udphdr.new();
hdr.lport = hdr.rport = RIPport;
hdr.raddr = dst; # needn't copy
hdr.pack(buf, IP->Udphdrlen);
o := IP->Udphdrlen;
buf[o] = byte op;
buf[o+1] = byte myversion;
buf[o+2] = byte 0;
buf[o+3] = byte 0;
o += Riphdrlen;
# rips := buf[IP->Udphdrlen+Riphdrlen:];
if(op == OpRequest){
buf[o:] = zeroentry;
ip->put4(buf, o+Ometric, HopLimit);
o += Ipdestlen;
} else {
# send routes
for(i:=0; i<len routes; i++){
r := routes[i];
if(r == nil || !r.valid || changes && !r.changed)
continue;
if(r == defroute)
continue;
if(r.dest.eq(ifc.net) || isonnet(r.dest, ifc))
continue;
netmask := r.dest.classmask();
subnet := !r.mask.eq(netmask);
if(myversion < 2 && !r.mask.eq(ip->allbits)){
# if not a host route, don't let a subnet route leave its net
if(subnet && !netmask.eq(ifc.ip.classmask()))
continue;
}
if(o+Ipdestlen > IP->Udphdrlen+Maxripmsg){
if(sys->write(netfd, buf, o) < 0)
sys->fprint(sys->fildes(2), "RIP write failed: %r\n");
o = IP->Udphdrlen + Riphdrlen;
}
buf[o:] = zeroentry;
ip->put2(buf, o+Otype, AF_INET);
buf[o+Oaddr:] = r.dest.v4();
ip->put4(buf, o+Ometric, r.metric);
if(myversion == 2 && subnet)
buf[o+Omask:] = r.mask.v4();
o += Ipdestlen;
}
}
if(o > IP->Udphdrlen+Riphdrlen && sys->write(netfd, buf, o) < 0)
sys->fprint(sys->fildes(2), "rip: network write to %s failed: %r\n", dst.text());
}
lookup(addr: IPaddr): ref Gateway
{
avail := -1;
for(i:=0; i<len routes; i++){
g := routes[i];
if(g == nil || !g.valid){
if(avail < 0)
avail = i;
continue;
}
if(g.dest.eq(addr))
return g;
}
if(avail < 0){
avail = len routes;
a := array[len routes+Routeinc] of ref Gateway;
a[0:] = routes;
routes = a;
}
if((g := routes[avail]) == nil){
g = ref Gateway;
routes[avail] = g;
g.valid = 0;
}
g.dest = addr;
return g;
}
findroute(a: IPaddr): ref Gateway
{
pr: ref Gateway;
for(i:=0; i<len routes; i++){
r := routes[i];
if(r == nil || !r.valid)
continue;
if(r.contains(a) && (pr == nil || !maskle(r.mask, pr.mask)))
pr = r; # more specific mask
}
return pr;
}
maskgen(addr: IPaddr): IPaddr
{
net: ref Ifcaddr;
for(l := nets; l != nil; l = tl l){
ifc := hd l;
if(isonnet(addr, ifc) &&
(net == nil || maskle(ifc.mask, net.mask))) # less specific mask?
net = ifc;
}
if(net != nil)
return net.mask;
return addr.classmask();
}
isonnet(a: IPaddr, n: ref Ifcaddr): int
{
return a.mask(n.mask).eq(n.net);
}
isbroadcast(a: IPaddr, mask: IPaddr): int
{
h := a.maskn(mask); # host part
hm := (ip->allbits).maskn(mask); # host part of mask
return h.eq(hm);
}
iszero(a: IPaddr): int
{
return a.eq(ip->v4noaddr) || a.eq(ip->noaddr);
}
maskle(a, b: IPaddr): int
{
return a.mask(b).eq(a);
}
#
# add ipdest mask gateway
# add 0.0.0.0 0.0.0.0 gateway (default)
# delete ipdest mask
#
addroute(g: ref Gateway)
{
if(iszero(g.mask) && iszero(g.dest))
g.valid = 0; # don't change default route
else if(defroute != nil && defroute.gateway.eq(g.gateway)){
if(debug)
syslog(0, logfile, sys->sprint("default %s %s", g.dest.text(), g.mask.text())); # don't need a new entry
g.valid = 1;
g.changed = 1;
} else {
if(debug)
syslog(0, logfile, sys->sprint("add %s %s %s", g.dest.text(), g.mask.text(), g.gateway.text()));
if(nochange || sys->fprint(routefd, "add %s %s %s", g.dest.text(), g.mask.text(), g.gateway.text()) > 0){
g.valid = 1;
g.changed = 1;
}
}
}
delroute(g: ref Gateway)
{
if(debug)
syslog(0, logfile, sys->sprint("delete %s %s", g.dest.text(), g.mask.text()));
if(!nochange)
sys->fprint(routefd, "delete %s %s", g.dest.text(), g.mask.text());
}
parseip(s: string): IPaddr
{
(ok, a) := IPaddr.parse(s);
if(ok < 0)
raise "bad route";
return a;
}
parsemask(s: string): IPaddr
{
(ok, a) := IPaddr.parsemask(s);
if(ok < 0)
raise "bad route";
return a;
}
contains(s: string, t: string): int
{
for(i := 0; i < len s; i++)
for(j := 0; j < len t; j++)
if(s[i] == t[j])
return 1;
return 0;
}
Gateway.contains(g: self ref Gateway, a: IPaddr): int
{
return g.dest.eq(a.mask(g.mask));
}
riplisten(): ref Sys->FD
{
addr := sys->sprint("%s/udp!*!rip", netdir);
c := dial->announce(addr);
if(c == nil)
fatal(sys->sprint("can't announce %s: %r", addr));
if(sys->fprint(c.cfd, "headers") < 0)
fatal(sys->sprint("can't set udp headers: %r"));
fd := sys->open(c.dir+"/data", Sys->ORDWR);
if(fd == nil)
fatal(sys->sprint("can't open %s: %r", c.dir+"/data"));
return fd;
}
fatal(s: string)
{
syslog(0, logfile, s);
raise "fail:error";
}