typedef struct Rarp Rarp;

#include <u.h>
#include <libc.h>
#include <bio.h>
#include <ip.h>
#include <ndb.h>
#include "arp.h"

typedef struct Rarp Rarp;

struct Rarp
{
uchar edst[6];
uchar esrc[6];
uchar type[2];
uchar hrd[2];
uchar pro[2];
uchar hln;
uchar pln;
uchar op[2];
uchar sha[6];
uchar spa[4];
uchar tha[6];
uchar tpa[4];
};

uchar myip[IPaddrlen];
uchar myether[6];
char rlog[] = "ipboot";
char *device = "ether0";
int debug;
Ndb *db;

char* lookup(char*, char*, char*, char*, int);

void
error(char *s)
{
syslog(1, rlog, "error %s: %r", s);
exits(s);
}

char net[32];

void
usage(void)
{
fprint(2, "usage: %s [-e device] [-x netmtpt] [-f ndb-file] [-d]\n", argv0);
exits("usage");
}

void
main(int argc, char *argv[])
{
int edata, ectl;
uchar buf[2048];
long n;
Rarp *rp;
char ebuf[16];
char ipbuf[64];
char file[128];
int arp;
char *p, *ndbfile;

ndbfile = nil;
setnetmtpt(net, sizeof(net), nil);
ARGBEGIN{
case 'e':
p = ARGF();
if(p == nil)
usage();
device = p;
break;
case 'd':
debug = 1;
break;
case 'f':
p = ARGF();
if(p == nil)
usage();
ndbfile = p;
break;
case 'x':
p = ARGF();
if(p == nil)
usage();
setnetmtpt(net, sizeof(net), p);
break;
}ARGEND
USED(argc, argv);

fmtinstall('E', eipfmt);
fmtinstall('I', eipfmt);
fmtinstall('V', eipfmt);

db = ndbopen(ndbfile);
if(db == 0)
error("can't open the database");

edata = dial(netmkaddr("0x8035", device, 0), 0, 0, &ectl);
if(edata < 0)
error("can't open ethernet");

if(myipaddr(myip, net) < 0)
error("can't get my ip address");
sprint(ebuf, "%s/%s", net, device);
if(myetheraddr(myether, ebuf) < 0)
error("can't get my ether address");

snprint(file, sizeof(file), "%s/arp", net);
if((arp = open(file, ORDWR)) < 0)
fprint(2, "rarpd: can't open %s\n", file);

switch(rfork(RFNOTEG|RFPROC|RFFDG)) {
case -1:
error("fork");
case 0:
break;
default:
exits(0);
}

for(;;){
n = read(edata, buf, sizeof(buf));
if(n <= 0)
error("reading");
if(n < sizeof(Rarp)){
syslog(debug, rlog, "bad packet size %ld", n);
continue;
}
rp = (Rarp*)buf;
if(rp->op[0]!=0 && rp->op[1]!=3){
syslog(debug, rlog, "bad op %d %d %E",
rp->op[1], rp->op[0], rp->esrc);
continue;
}

if(debug)
syslog(debug, rlog, "rcv se %E si %V te %E ti %V",
rp->sha, rp->spa, rp->tha, rp->tpa);

sprint(ebuf, "%E", rp->tha);
if(lookup("ether", ebuf, "ip", ipbuf, sizeof ipbuf) == nil){
syslog(debug, rlog, "client lookup failed: %s", ebuf);
continue;
}
v4parseip(rp->tpa, ipbuf);

memmove(rp->sha, myether, sizeof(rp->sha));
v6tov4(rp->spa, myip);

rp->op[0] = 0;
rp->op[1] = 4;
memmove(rp->edst, rp->esrc, sizeof(rp->edst));

if(debug)
syslog(debug, rlog, "send se %E si %V te %E ti %V",
rp->sha, rp->spa, rp->tha, rp->tpa);

if(write(edata, buf, 60) != 60)
error("write failed");

if(arp < 0)
continue;
if(fprint(arp, "add %E %V", rp->esrc, rp->tpa) < 0)
fprint(2, "can't write arp entry\n");
}
}

char*
lookup(char *sattr, char *sval, char *tattr, char *tval, int len)
{
static Ndb *db;
char *attrs[1];
Ndbtuple *t;

if(db == nil)
db = ndbopen(0);
if(db == nil)
return nil;

if(sattr == nil)
sattr = ipattr(sval);

attrs[0] = tattr;
t = ndbipinfo(db, sattr, sval, attrs, 1);
if(t == nil)
return nil;
strncpy(tval, t->val, len);
tval[len-1] = 0;
ndbfree(t);
return tval;
}