ref: 8726990cf563f72d91e1cb8335510d5a1d38ec02
dir: /sys/src/9/ip/icmp.c/
#include "u.h"
#include "../port/lib.h"
#include "mem.h"
#include "dat.h"
#include "fns.h"
#include "../port/error.h"
#include "ip.h"
typedef struct Icmp {
uchar vihl; /* Version and header length */
uchar tos; /* Type of service */
uchar length[2]; /* packet length */
uchar id[2]; /* Identification */
uchar frag[2]; /* Fragment information */
uchar ttl; /* Time to live */
uchar proto; /* Protocol */
uchar ipcksum[2]; /* Header checksum */
uchar src[4]; /* Ip source */
uchar dst[4]; /* Ip destination */
uchar type;
uchar code;
uchar cksum[2];
uchar icmpid[2];
uchar seq[2];
uchar data[1];
} Icmp;
enum { /* Packet Types */
EchoReply = 0,
Unreachable = 3,
SrcQuench = 4,
Redirect = 5,
EchoRequest = 8,
TimeExceed = 11,
InParmProblem = 12,
Timestamp = 13,
TimestampReply = 14,
InfoRequest = 15,
InfoReply = 16,
AddrMaskRequest = 17,
AddrMaskReply = 18,
Maxtype = 18,
};
enum
{
MinAdvise = 24, /* minimum needed for us to advise another protocol */
};
char *icmpnames[Maxtype+1] =
{
[EchoReply] "EchoReply",
[Unreachable] "Unreachable",
[SrcQuench] "SrcQuench",
[Redirect] "Redirect",
[EchoRequest] "EchoRequest",
[TimeExceed] "TimeExceed",
[InParmProblem] "InParmProblem",
[Timestamp] "Timestamp",
[TimestampReply] "TimestampReply",
[InfoRequest] "InfoRequest",
[InfoReply] "InfoReply",
[AddrMaskRequest] "AddrMaskRequest",
[AddrMaskReply ] "AddrMaskReply ",
};
enum {
IP_ICMPPROTO = 1,
ICMP_IPSIZE = 20,
ICMP_HDRSIZE = 8,
};
enum
{
InMsgs,
InErrors,
OutMsgs,
CsumErrs,
LenErrs,
HlenErrs,
Nstats,
};
static char *statnames[Nstats] =
{
[InMsgs] "InMsgs",
[InErrors] "InErrors",
[OutMsgs] "OutMsgs",
[CsumErrs] "CsumErrs",
[LenErrs] "LenErrs",
[HlenErrs] "HlenErrs",
};
typedef struct Icmppriv Icmppriv;
struct Icmppriv
{
ulong stats[Nstats];
/* message counts */
ulong in[Maxtype+1];
ulong out[Maxtype+1];
};
static void icmpkick(void *x, Block*);
static void
icmpcreate(Conv *c)
{
c->rq = qopen(64*1024, Qmsg, 0, c);
c->wq = qbypass(icmpkick, c);
}
extern char*
icmpconnect(Conv *c, char **argv, int argc)
{
char *e;
e = Fsstdconnect(c, argv, argc);
if(e != nil)
return e;
Fsconnected(c, e);
return nil;
}
extern int
icmpstate(Conv *c, char *state, int n)
{
USED(c);
return snprint(state, n, "%s qin %d qout %d\n",
"Datagram",
c->rq ? qlen(c->rq) : 0,
c->wq ? qlen(c->wq) : 0
);
}
extern char*
icmpannounce(Conv *c, char **argv, int argc)
{
char *e;
e = Fsstdannounce(c, argv, argc);
if(e != nil)
return e;
Fsconnected(c, nil);
return nil;
}
extern void
icmpclose(Conv *c)
{
qclose(c->rq);
qclose(c->wq);
ipmove(c->laddr, IPnoaddr);
ipmove(c->raddr, IPnoaddr);
c->lport = 0;
}
static void
icmpkick(void *x, Block *bp)
{
Conv *c = x;
Icmp *p;
Icmppriv *ipriv;
if(bp == nil)
return;
if(blocklen(bp) < ICMP_IPSIZE + ICMP_HDRSIZE){
freeblist(bp);
return;
}
p = (Icmp *)(bp->rp);
p->vihl = IP_VER4;
ipriv = c->p->priv;
if(p->type <= Maxtype)
ipriv->out[p->type]++;
v6tov4(p->dst, c->raddr);
v6tov4(p->src, c->laddr);
p->proto = IP_ICMPPROTO;
hnputs(p->icmpid, c->lport);
memset(p->cksum, 0, sizeof(p->cksum));
hnputs(p->cksum, ptclcsum(bp, ICMP_IPSIZE, blocklen(bp) - ICMP_IPSIZE));
ipriv->stats[OutMsgs]++;
ipoput4(c->p->f, bp, 0, c->ttl, c->tos, nil);
}
extern void
icmpttlexceeded(Fs *f, uchar *ia, Block *bp)
{
Block *nbp;
Icmp *p, *np;
p = (Icmp *)bp->rp;
netlog(f, Logicmp, "sending icmpttlexceeded -> %V\n", p->src);
nbp = allocb(ICMP_IPSIZE + ICMP_HDRSIZE + ICMP_IPSIZE + 8);
nbp->wp += ICMP_IPSIZE + ICMP_HDRSIZE + ICMP_IPSIZE + 8;
np = (Icmp *)nbp->rp;
np->vihl = IP_VER4;
memmove(np->dst, p->src, sizeof(np->dst));
v6tov4(np->src, ia);
memmove(np->data, bp->rp, ICMP_IPSIZE + 8);
np->type = TimeExceed;
np->code = 0;
np->proto = IP_ICMPPROTO;
hnputs(np->icmpid, 0);
hnputs(np->seq, 0);
memset(np->cksum, 0, sizeof(np->cksum));
hnputs(np->cksum, ptclcsum(nbp, ICMP_IPSIZE, blocklen(nbp) - ICMP_IPSIZE));
ipoput4(f, nbp, 0, MAXTTL, DFLTTOS, nil);
}
static void
icmpunreachable(Fs *f, Block *bp, int code, int seq)
{
Block *nbp;
Icmp *p, *np;
int i;
uchar addr[IPaddrlen];
p = (Icmp *)bp->rp;
/* only do this for unicast sources and destinations */
v4tov6(addr, p->dst);
i = ipforme(f, addr);
if((i&Runi) == 0)
return;
v4tov6(addr, p->src);
i = ipforme(f, addr);
if(i != 0 && (i&Runi) == 0)
return;
netlog(f, Logicmp, "sending icmpnoconv -> %V\n", p->src);
nbp = allocb(ICMP_IPSIZE + ICMP_HDRSIZE + ICMP_IPSIZE + 8);
nbp->wp += ICMP_IPSIZE + ICMP_HDRSIZE + ICMP_IPSIZE + 8;
np = (Icmp *)nbp->rp;
np->vihl = IP_VER4;
memmove(np->dst, p->src, sizeof(np->dst));
memmove(np->src, p->dst, sizeof(np->src));
memmove(np->data, bp->rp, ICMP_IPSIZE + 8);
np->type = Unreachable;
np->code = code;
np->proto = IP_ICMPPROTO;
hnputs(np->icmpid, 0);
hnputs(np->seq, seq);
memset(np->cksum, 0, sizeof(np->cksum));
hnputs(np->cksum, ptclcsum(nbp, ICMP_IPSIZE, blocklen(nbp) - ICMP_IPSIZE));
ipoput4(f, nbp, 0, MAXTTL, DFLTTOS, nil);
}
extern void
icmpnoconv(Fs *f, Block *bp)
{
icmpunreachable(f, bp, 3, 0);
}
extern void
icmpcantfrag(Fs *f, Block *bp, int mtu)
{
icmpunreachable(f, bp, 4, mtu);
}
static void
goticmpkt(Proto *icmp, Block *bp)
{
Conv **c, *s;
Icmp *p;
uchar dst[IPaddrlen];
ushort recid;
p = (Icmp *) bp->rp;
v4tov6(dst, p->src);
recid = nhgets(p->icmpid);
for(c = icmp->conv; *c; c++) {
s = *c;
if(s->lport == recid)
if(ipcmp(s->raddr, dst) == 0){
bp = concatblock(bp);
if(bp != nil)
qpass(s->rq, bp);
return;
}
}
freeblist(bp);
}
static Block *
mkechoreply(Block *bp)
{
Icmp *q;
uchar ip[4];
q = (Icmp *)bp->rp;
q->vihl = IP_VER4;
memmove(ip, q->src, sizeof(q->dst));
memmove(q->src, q->dst, sizeof(q->src));
memmove(q->dst, ip, sizeof(q->dst));
q->type = EchoReply;
memset(q->cksum, 0, sizeof(q->cksum));
hnputs(q->cksum, ptclcsum(bp, ICMP_IPSIZE, blocklen(bp) - ICMP_IPSIZE));
return bp;
}
static char *unreachcode[] =
{
[0] "net unreachable",
[1] "host unreachable",
[2] "protocol unreachable",
[3] "port unreachable",
[4] "fragmentation needed and DF set",
[5] "source route failed",
[6] "destination network unknown",
[7] "destination host unknown",
[8] "source host isolated",
[9] "network administratively prohibited",
[10] "host administratively prohibited",
[11] "network unreachable for tos",
[12] "host unreachable for tos",
[13] "communication administratively prohibited",
[14] "host precedence violation",
[15] "precedence cutoff in effect",
};
static void
icmpiput(Proto *icmp, Ipifc*, Block *bp)
{
int n, iplen;
Icmp *p;
Block *r;
Proto *pr;
char *msg;
char m2[128];
Icmppriv *ipriv;
ipriv = icmp->priv;
ipriv->stats[InMsgs]++;
p = (Icmp *)bp->rp;
netlog(icmp->f, Logicmp, "icmpiput %s (%d) %d\n",
(p->type < nelem(icmpnames)? icmpnames[p->type]: ""),
p->type, p->code);
n = blocklen(bp);
if(n < ICMP_IPSIZE+ICMP_HDRSIZE){
ipriv->stats[InErrors]++;
ipriv->stats[HlenErrs]++;
netlog(icmp->f, Logicmp, "icmp hlen %d\n", n);
goto raise;
}
iplen = nhgets(p->length);
if(iplen > n){
ipriv->stats[LenErrs]++;
ipriv->stats[InErrors]++;
netlog(icmp->f, Logicmp, "icmp length %d\n", iplen);
goto raise;
}
if(ptclcsum(bp, ICMP_IPSIZE, iplen - ICMP_IPSIZE)){
ipriv->stats[InErrors]++;
ipriv->stats[CsumErrs]++;
netlog(icmp->f, Logicmp, "icmp checksum error\n");
goto raise;
}
if(p->type <= Maxtype)
ipriv->in[p->type]++;
switch(p->type) {
case EchoRequest:
if (iplen < n)
bp = trimblock(bp, 0, iplen);
r = mkechoreply(concatblock(bp));
ipriv->out[EchoReply]++;
ipoput4(icmp->f, r, 0, MAXTTL, DFLTTOS, nil);
break;
case Unreachable:
if(p->code >= nelem(unreachcode)) {
snprint(m2, sizeof m2, "unreachable %V->%V code %d",
p->src, p->dst, p->code);
msg = m2;
} else
msg = unreachcode[p->code];
bp->rp += ICMP_IPSIZE+ICMP_HDRSIZE;
if(blocklen(bp) < MinAdvise){
ipriv->stats[LenErrs]++;
goto raise;
}
p = (Icmp *)bp->rp;
pr = Fsrcvpcolx(icmp->f, p->proto);
if(pr != nil && pr->advise != nil) {
(*pr->advise)(pr, bp, msg);
return;
}
bp->rp -= ICMP_IPSIZE+ICMP_HDRSIZE;
goticmpkt(icmp, bp);
break;
case TimeExceed:
if(p->code == 0){
snprint(m2, sizeof m2, "ttl exceeded at %V", p->src);
bp->rp += ICMP_IPSIZE+ICMP_HDRSIZE;
if(blocklen(bp) < MinAdvise){
ipriv->stats[LenErrs]++;
goto raise;
}
p = (Icmp *)bp->rp;
pr = Fsrcvpcolx(icmp->f, p->proto);
if(pr != nil && pr->advise != nil) {
(*pr->advise)(pr, bp, m2);
return;
}
bp->rp -= ICMP_IPSIZE+ICMP_HDRSIZE;
}
goticmpkt(icmp, bp);
break;
default:
goticmpkt(icmp, bp);
break;
}
return;
raise:
freeblist(bp);
}
void
icmpadvise(Proto *icmp, Block *bp, char *msg)
{
Conv **c, *s;
Icmp *p;
uchar dst[IPaddrlen];
ushort recid;
p = (Icmp *) bp->rp;
v4tov6(dst, p->dst);
recid = nhgets(p->icmpid);
for(c = icmp->conv; *c; c++) {
s = *c;
if(s->lport == recid)
if(ipcmp(s->raddr, dst) == 0){
if(s->ignoreadvice)
break;
qhangup(s->rq, msg);
qhangup(s->wq, msg);
break;
}
}
freeblist(bp);
}
int
icmpstats(Proto *icmp, char *buf, int len)
{
Icmppriv *priv;
char *p, *e;
int i;
priv = icmp->priv;
p = buf;
e = p+len;
for(i = 0; i < Nstats; i++)
p = seprint(p, e, "%s: %lud\n", statnames[i], priv->stats[i]);
for(i = 0; i <= Maxtype; i++){
if(icmpnames[i])
p = seprint(p, e, "%s: %lud %lud\n", icmpnames[i], priv->in[i], priv->out[i]);
else
p = seprint(p, e, "%d: %lud %lud\n", i, priv->in[i], priv->out[i]);
}
return p - buf;
}
void
icmpinit(Fs *fs)
{
Proto *icmp;
icmp = smalloc(sizeof(Proto));
icmp->priv = smalloc(sizeof(Icmppriv));
icmp->name = "icmp";
icmp->connect = icmpconnect;
icmp->announce = icmpannounce;
icmp->state = icmpstate;
icmp->create = icmpcreate;
icmp->close = icmpclose;
icmp->rcv = icmpiput;
icmp->stats = icmpstats;
icmp->ctl = nil;
icmp->advise = icmpadvise;
icmp->gc = nil;
icmp->ipproto = IP_ICMPPROTO;
icmp->nc = 128;
icmp->ptclsize = 0;
Fsproto(fs, icmp);
}