ref: ce1edc34368d192db7d3421673ca98c19cc792b2
dir: /sys/src/cmd/ip/dhcpclient.c/
#include <u.h>
#include <libc.h>
#include <ip.h>
#include "dhcp.h"
void bootpdump(uchar *p, int n);
void dhcpinit(void);
void dhcprecv(void);
void dhcpsend(int);
void myfatal(char *fmt, ...);
int openlisten(char*);
uchar *optaddaddr(uchar*, int, uchar*);
uchar *optaddbyte(uchar*, int, int);
uchar *optadd(uchar*, int, void*, int);
uchar *optaddulong(uchar*, int, ulong);
uchar *optget(Bootp*, int, int);
int optgetaddr(Bootp*, int, uchar*);
int optgetbyte(Bootp*, int);
ulong optgetulong(Bootp*, int);
Bootp *parse(uchar*, int);
void stdinthread(void*);
ulong thread(void(*f)(void*), void *a);
void timerthread(void*);
void usage(void);
struct {
QLock lk;
int state;
int fd;
ulong xid;
ulong starttime;
char cid[100];
char sname[64];
uchar server[IPaddrlen]; /* server IP address */
uchar client[IPaddrlen]; /* client IP address */
uchar mask[IPaddrlen]; /* client mask */
ulong lease; /* lease time */
ulong resend; /* number of resends for current state */
ulong timeout; /* time to timeout - seconds */
} dhcp;
char net[64];
char optmagic[4] = { 0x63, 0x82, 0x53, 0x63 };
void
main(int argc, char *argv[])
{
char *p;
setnetmtpt(net, sizeof(net), nil);
ARGBEGIN{
case 'x':
p = ARGF();
if(p == nil)
usage();
setnetmtpt(net, sizeof(net), p);
}ARGEND;
fmtinstall('E', eipfmt);
fmtinstall('I', eipfmt);
fmtinstall('V', eipfmt);
dhcpinit();
rfork(RFNOTEG|RFREND);
thread(timerthread, 0);
thread(stdinthread, 0);
qlock(&dhcp.lk);
dhcp.starttime = time(0);
dhcp.fd = openlisten(net);
dhcpsend(Discover);
dhcp.state = Sselecting;
dhcp.resend = 0;
dhcp.timeout = 4;
while(dhcp.state != Sbound)
dhcprecv();
/* allows other clients on this machine */
close(dhcp.fd);
dhcp.fd = -1;
print("ip=%I\n", dhcp.client);
print("mask=%I\n", dhcp.mask);
print("end\n");
/* keep lease alive */
for(;;) {
//fprint(2, "got lease for %d\n", dhcp.lease);
qunlock(&dhcp.lk);
sleep(dhcp.lease*500); /* wait half of lease time */
qlock(&dhcp.lk);
//fprint(2, "try renue\n", dhcp.lease);
dhcp.starttime = time(0);
dhcp.fd = openlisten(net);
dhcp.xid = time(0)*getpid();
dhcpsend(Request);
dhcp.state = Srenewing;
dhcp.resend = 0;
dhcp.timeout = 1;
while(dhcp.state != Sbound)
dhcprecv();
/* allows other clients on this machine */
close(dhcp.fd);
dhcp.fd = -1;
}
}
void
usage(void)
{
fprint(2, "usage: %s [-x netextension]\n", argv0);
exits("usage");
}
void
timerthread(void*)
{
for(;;) {
sleep(1000);
qlock(&dhcp.lk);
if(--dhcp.timeout > 0) {
qunlock(&dhcp.lk);
continue;
}
switch(dhcp.state) {
default:
myfatal("timerthread: unknown state %d", dhcp.state);
case Sinit:
break;
case Sselecting:
dhcpsend(Discover);
dhcp.timeout = 4;
dhcp.resend++;
if(dhcp.resend>5)
myfatal("dhcp: giving up: selecting");
break;
case Srequesting:
dhcpsend(Request);
dhcp.timeout = 4;
dhcp.resend++;
if(dhcp.resend>5)
myfatal("dhcp: giving up: requesting");
break;
case Srenewing:
dhcpsend(Request);
dhcp.timeout = 1;
dhcp.resend++;
if(dhcp.resend>3) {
dhcp.state = Srebinding;
dhcp.resend = 0;
}
break;
case Srebinding:
dhcpsend(Request);
dhcp.timeout = 4;
dhcp.resend++;
if(dhcp.resend>5)
myfatal("dhcp: giving up: rebinding");
break;
case Sbound:
break;
}
qunlock(&dhcp.lk);
}
}
void
stdinthread(void*)
{
uchar buf[100];
int n;
for(;;) {
n = read(0, buf, sizeof(buf));
if(n <= 0)
break;
}
/* shutdown cleanly */
qlock(&dhcp.lk);
if(dhcp.client) {
if(dhcp.fd < 0)
dhcp.fd = openlisten(net);
dhcpsend(Release);
}
qunlock(&dhcp.lk);
postnote(PNGROUP, getpid(), "die");
exits(0);
}
void
dhcpinit(void)
{
int fd;
dhcp.state = Sinit;
dhcp.timeout = 4;
fd = open("/dev/random", 0);
if(fd >= 0) {
read(fd, &dhcp.xid, sizeof(dhcp.xid));
close(fd);
} else
dhcp.xid = time(0)*getpid();
srand(dhcp.xid);
sprint(dhcp.cid, "%s.%d", getenv("sysname"), getpid());
}
void
dhcpsend(int type)
{
int n;
uchar *p;
Bootp bp;
Udphdr *up;
memset(&bp, 0, sizeof bp);
up = (Udphdr*)bp.udphdr;
hnputs(up->rport, 67);
bp.op = Bootrequest;
hnputl(bp.xid, dhcp.xid);
hnputs(bp.secs, time(0) - dhcp.starttime);
hnputs(bp.flags, Fbroadcast); /* reply must be broadcast */
memmove(bp.optmagic, optmagic, 4);
p = bp.optdata;
p = optaddbyte(p, ODtype, type);
p = optadd(p, ODclientid, dhcp.cid, strlen(dhcp.cid));
switch(type) {
default:
myfatal("dhcpsend: unknown message type: %d", type);
case Discover:
ipmove(up->raddr, IPv4bcast); /* broadcast */
break;
case Request:
if(dhcp.state == Sbound || dhcp.state == Srenewing)
ipmove(up->raddr, dhcp.server);
else
ipmove(up->raddr, IPv4bcast); /* broadcast */
p = optaddulong(p, ODlease, dhcp.lease);
if(dhcp.state == Sselecting || dhcp.state == Srequesting) {
p = optaddaddr(p, ODipaddr, dhcp.client); /* mistake?? */
p = optaddaddr(p, ODserverid, dhcp.server);
} else
v6tov4(bp.ciaddr, dhcp.client);
break;
case Release:
ipmove(up->raddr, dhcp.server);
v6tov4(bp.ciaddr, dhcp.client);
p = optaddaddr(p, ODipaddr, dhcp.client);
p = optaddaddr(p, ODserverid, dhcp.server);
break;
}
*p++ = OBend;
n = p - (uchar*)&bp;
if(write(dhcp.fd, &bp, n) != n)
myfatal("dhcpsend: write failed: %r");
}
void
dhcprecv(void)
{
uchar buf[2000];
Bootp *bp;
int n, type;
ulong lease;
uchar mask[IPaddrlen];
qunlock(&dhcp.lk);
n = read(dhcp.fd, buf, sizeof(buf));
qlock(&dhcp.lk);
if(n <= 0)
myfatal("dhcprecv: bad read: %r");
bp = parse(buf, n);
if(bp == 0)
return;
if(1) {
fprint(2, "recved\n");
bootpdump(buf, n);
}
type = optgetbyte(bp, ODtype);
switch(type) {
default:
fprint(2, "dhcprecv: unknown type: %d\n", type);
break;
case Offer:
if(dhcp.state != Sselecting)
break;
lease = optgetulong(bp, ODlease);
if(lease == 0)
myfatal("bad lease");
if(!optgetaddr(bp, OBmask, mask))
memset(mask, 0xff, sizeof(mask));
v4tov6(dhcp.client, bp->yiaddr);
if(!optgetaddr(bp, ODserverid, dhcp.server)) {
fprint(2, "dhcprecv: Offer from server with invalid serverid\n");
break;
}
dhcp.lease = lease;
ipmove(dhcp.mask, mask);
memmove(dhcp.sname, bp->sname, sizeof(dhcp.sname));
dhcp.sname[sizeof(dhcp.sname)-1] = 0;
dhcpsend(Request);
dhcp.state = Srequesting;
dhcp.resend = 0;
dhcp.timeout = 4;
break;
case Ack:
if(dhcp.state != Srequesting)
if(dhcp.state != Srenewing)
if(dhcp.state != Srebinding)
break;
lease = optgetulong(bp, ODlease);
if(lease == 0)
myfatal("bad lease");
if(!optgetaddr(bp, OBmask, mask))
memset(mask, 0xff, sizeof(mask));
v4tov6(dhcp.client, bp->yiaddr);
dhcp.lease = lease;
ipmove(dhcp.mask, mask);
dhcp.state = Sbound;
break;
case Nak:
myfatal("recved nak");
break;
}
}
int
openlisten(char *net)
{
int n, fd, cfd;
char data[128], devdir[40];
// sprint(data, "%s/udp!*!bootpc", net);
sprint(data, "%s/udp!*!68", net);
for(n = 0; ; n++) {
cfd = announce(data, devdir);
if(cfd >= 0)
break;
/* might be another client - wait and try again */
fprint(2, "dhcpclient: can't announce %s: %r", data);
sleep(1000);
if(n > 10)
myfatal("can't announce: giving up: %r");
}
if(fprint(cfd, "headers") < 0)
myfatal("can't set header mode: %r");
sprint(data, "%s/data", devdir);
fd = open(data, ORDWR);
if(fd < 0)
myfatal("open %s: %r", data);
close(cfd);
return fd;
}
uchar*
optadd(uchar *p, int op, void *d, int n)
{
p[0] = op;
p[1] = n;
memmove(p+2, d, n);
return p+n+2;
}
uchar*
optaddbyte(uchar *p, int op, int b)
{
p[0] = op;
p[1] = 1;
p[2] = b;
return p+3;
}
uchar*
optaddulong(uchar *p, int op, ulong x)
{
p[0] = op;
p[1] = 4;
hnputl(p+2, x);
return p+6;
}
uchar *
optaddaddr(uchar *p, int op, uchar *ip)
{
p[0] = op;
p[1] = 4;
v6tov4(p+2, ip);
return p+6;
}
uchar*
optget(Bootp *bp, int op, int n)
{
int len, code;
uchar *p;
p = bp->optdata;
for(;;) {
code = *p++;
if(code == OBpad)
continue;
if(code == OBend)
return 0;
len = *p++;
if(code != op) {
p += len;
continue;
}
if(n && n != len)
return 0;
return p;
}
}
int
optgetbyte(Bootp *bp, int op)
{
uchar *p;
p = optget(bp, op, 1);
if(p == 0)
return 0;
return *p;
}
ulong
optgetulong(Bootp *bp, int op)
{
uchar *p;
p = optget(bp, op, 4);
if(p == 0)
return 0;
return nhgetl(p);
}
int
optgetaddr(Bootp *bp, int op, uchar *ip)
{
uchar *p;
p = optget(bp, op, 4);
if(p == 0)
return 0;
v4tov6(ip, p);
return 1;
}
/* make sure packet looks ok */
Bootp *
parse(uchar *p, int n)
{
int len, code;
Bootp *bp;
bp = (Bootp*)p;
if(n < bp->optmagic - p) {
fprint(2, "dhcpclient: parse: short bootp packet");
return 0;
}
if(dhcp.xid != nhgetl(bp->xid)) {
fprint(2, "dhcpclient: parse: bad xid: got %ux expected %lux\n",
nhgetl(bp->xid), dhcp.xid);
return 0;
}
if(bp->op != Bootreply) {
fprint(2, "dhcpclient: parse: bad op\n");
return 0;
}
n -= bp->optmagic - p;
p = bp->optmagic;
if(n < 4) {
fprint(2, "dhcpclient: parse: not option data");
return 0;
}
if(memcmp(optmagic, p, 4) != 0) {
fprint(2, "dhcpclient: parse: bad opt magic %ux %ux %ux %ux\n",
p[0], p[1], p[2], p[3]);
return 0;
}
p += 4;
n -= 4;
while(n>0) {
code = *p++;
n--;
if(code == OBpad)
continue;
if(code == OBend)
return bp;
if(n == 0) {
fprint(2, "dhcpclient: parse: bad option: %d", code);
return 0;
}
len = *p++;
n--;
if(len > n) {
fprint(2, "dhcpclient: parse: bad option: %d", code);
return 0;
}
p += len;
n -= len;
}
/* fix up nonstandard packets */
/* assume there is space */
*p = OBend;
return bp;
}
void
bootpdump(uchar *p, int n)
{
int len, i, code;
Bootp *bp;
Udphdr *up;
bp = (Bootp*)p;
up = (Udphdr*)bp->udphdr;
if(n < bp->optmagic - p) {
fprint(2, "dhcpclient: short bootp packet");
return;
}
fprint(2, "laddr=%I lport=%d raddr=%I rport=%d\n", up->laddr,
nhgets(up->lport), up->raddr, nhgets(up->rport));
fprint(2, "op=%d htype=%d hlen=%d hops=%d\n", bp->op, bp->htype,
bp->hlen, bp->hops);
fprint(2, "xid=%ux secs=%d flags=%ux\n", nhgetl(bp->xid),
nhgets(bp->secs), nhgets(bp->flags));
fprint(2, "ciaddr=%V yiaddr=%V siaddr=%V giaddr=%V\n",
bp->ciaddr, bp->yiaddr, bp->siaddr, bp->giaddr);
fprint(2, "chaddr=");
for(i=0; i<16; i++)
fprint(2, "%ux ", bp->chaddr[i]);
fprint(2, "\n");
fprint(2, "sname=%s\n", bp->sname);
fprint(2, "file = %s\n", bp->file);
n -= bp->optmagic - p;
p = bp->optmagic;
if(n < 4)
return;
if(memcmp(optmagic, p, 4) != 0)
fprint(2, "dhcpclient: bad opt magic %ux %ux %ux %ux\n",
p[0], p[1], p[2], p[3]);
p += 4;
n -= 4;
while(n>0) {
code = *p++;
n--;
if(code == OBpad)
continue;
if(code == OBend)
break;
if(n == 0) {
fprint(2, " bad option: %d", code);
return;
}
len = *p++;
n--;
if(len > n) {
fprint(2, " bad option: %d", code);
return;
}
switch(code) {
default:
fprint(2, "unknown option %d\n", code);
for(i = 0; i<len; i++)
fprint(2, "%ux ", p[i]);
case ODtype:
fprint(2, "DHCP type %d\n", p[0]);
break;
case ODclientid:
fprint(2, "client id=");
for(i = 0; i<len; i++)
fprint(2, "%ux ", p[i]);
fprint(2, "\n");
break;
case ODlease:
fprint(2, "lease=%d\n", nhgetl(p));
break;
case ODserverid:
fprint(2, "server id=%V\n", p);
break;
case OBmask:
fprint(2, "mask=%V\n", p);
break;
case OBrouter:
fprint(2, "router=%V\n", p);
break;
}
p += len;
n -= len;
}
}
ulong
thread(void(*f)(void*), void *a)
{
int pid;
pid = rfork(RFNOWAIT|RFMEM|RFPROC);
if(pid < 0)
myfatal("rfork failed: %r");
if(pid != 0)
return pid;
(*f)(a);
return 0; /* never reaches here */
}
void
myfatal(char *fmt, ...)
{
char buf[1024];
va_list arg;
va_start(arg, fmt);
vseprint(buf, buf+sizeof(buf), fmt, arg);
va_end(arg);
fprint(2, "%s: %s\n", argv0, buf);
postnote(PNGROUP, getpid(), "die");
exits(buf);
}