ref: f24038d601ebe23a213ca1eaf2cf2faa47c22873
dir: /sys/src/9/ip/ip.c/
#include "u.h"
#include "../port/lib.h"
#include "mem.h"
#include "dat.h"
#include "fns.h"
#include "../port/error.h"
#include "ip.h"
static char *statnames[] =
{
[Forwarding] "Forwarding",
[DefaultTTL] "DefaultTTL",
[InReceives] "InReceives",
[InHdrErrors] "InHdrErrors",
[InAddrErrors] "InAddrErrors",
[ForwDatagrams] "ForwDatagrams",
[InUnknownProtos] "InUnknownProtos",
[InDiscards] "InDiscards",
[InDelivers] "InDelivers",
[OutRequests] "OutRequests",
[OutDiscards] "OutDiscards",
[OutNoRoutes] "OutNoRoutes",
[ReasmTimeout] "ReasmTimeout",
[ReasmReqds] "ReasmReqds",
[ReasmOKs] "ReasmOKs",
[ReasmFails] "ReasmFails",
[FragOKs] "FragOKs",
[FragFails] "FragFails",
[FragCreates] "FragCreates",
};
static Block* ip4reassemble(IP*, int, Block*);
static void ipfragfree4(IP*, Fragment4*);
static Fragment4* ipfragallo4(IP*);
static void
initfrag(IP *ip, int size)
{
Fragment4 *fq4, *eq4;
Fragment6 *fq6, *eq6;
ip->fragfree4 = (Fragment4*)malloc(sizeof(Fragment4) * size);
if(ip->fragfree4 == nil)
panic("initfrag");
eq4 = &ip->fragfree4[size];
for(fq4 = ip->fragfree4; fq4 < eq4; fq4++)
fq4->next = fq4+1;
ip->fragfree4[size-1].next = nil;
ip->fragfree6 = (Fragment6*)malloc(sizeof(Fragment6) * size);
if(ip->fragfree6 == nil)
panic("initfrag");
eq6 = &ip->fragfree6[size];
for(fq6 = ip->fragfree6; fq6 < eq6; fq6++)
fq6->next = fq6+1;
ip->fragfree6[size-1].next = nil;
}
void
ip_init(Fs *f)
{
IP *ip;
ip = smalloc(sizeof(IP));
ip->stats[DefaultTTL] = MAXTTL;
initfrag(ip, 100);
f->ip = ip;
ip_init_6(f);
}
void
iprouting(Fs *f, int on)
{
f->ip->iprouting = on;
if(f->ip->iprouting==0)
f->ip->stats[Forwarding] = 2;
else
f->ip->stats[Forwarding] = 1;
}
int
ipoput4(Fs *f, Block *bp, Ipifc *gating, int ttl, int tos, Routehint *rh)
{
Ipifc *ifc;
uchar *gate;
ulong fragoff;
Block *xp, *nb;
Ip4hdr *eh, *feh;
int lid, len, seglen, chunk, hlen, dlen, blklen, offset, medialen;
Route *r;
IP *ip;
int rv = 0;
ip = f->ip;
ip->stats[OutRequests]++;
/* Fill out the ip header */
eh = (Ip4hdr*)bp->rp;
assert(BLEN(bp) >= IP4HDR);
len = blocklen(bp);
if(len >= IP_MAX){
ip->stats[OutDiscards]++;
netlog(f, Logip, "%V -> %V: exceeded ip max size: %d\n", eh->src, eh->dst, len);
goto free;
}
r = v4lookup(f, eh->dst, eh->src, rh);
if(r == nil || (ifc = r->ifc) == nil){
ip->stats[OutNoRoutes]++;
netlog(f, Logip, "%V -> %V: no interface\n", eh->src, eh->dst);
rv = -1;
goto free;
}
if(r->type & (Rifc|Runi|Rbcast|Rmulti))
gate = eh->dst;
else
gate = r->v4.gate;
if(!canrlock(ifc)){
ip->stats[OutDiscards]++;
goto free;
}
if(waserror()){
runlock(ifc);
nexterror();
}
if(ifc->m == nil)
goto raise;
medialen = ifc->maxtu - ifc->m->hsize;
if(gating != nil) {
int mtu = gating->maxtu - gating->m->hsize;
if(medialen < mtu)
mtu = medialen;
tcpmssclamp(bp->rp, BLEN(bp), mtu);
} else {
eh->vihl = IP_VER4|IP_HLEN4;
eh->tos = tos;
}
eh->ttl = ttl;
/* If we dont need to fragment just send it */
if(len <= medialen) {
hnputs(eh->length, len);
if(gating == nil){
hnputs(eh->id, incref(&ip->id4));
eh->frag[0] = 0;
eh->frag[1] = 0;
}
eh->cksum[0] = 0;
eh->cksum[1] = 0;
hnputs(eh->cksum, ipcsum(&eh->vihl));
ipifcoput(ifc, bp, V4, gate, rh);
runlock(ifc);
poperror();
return 0;
}
if(eh->frag[0] & (IP_DF>>8)){
ip->stats[FragFails]++;
ip->stats[OutDiscards]++;
icmpcantfrag(f, gating!=nil? gating: ifc, bp, medialen);
netlog(f, Logip, "%V -> %V: can't fragment with DF flag set\n", eh->src, eh->dst);
goto raise;
}
hlen = (eh->vihl & 0xF)<<2;
seglen = (medialen - hlen) & ~7;
if(seglen < 8){
ip->stats[FragFails]++;
ip->stats[OutDiscards]++;
netlog(f, Logip, "%V -> %V: can't fragment with seglen < 8\n", eh->src, eh->dst);
goto raise;
}
dlen = len - hlen;
xp = bp;
if(gating)
lid = nhgets(eh->id);
else
lid = incref(&ip->id4);
offset = hlen;
while(offset && offset >= BLEN(xp)) {
offset -= BLEN(xp);
xp = xp->next;
}
xp->rp += offset;
if(gating)
fragoff = nhgets(eh->frag)<<3;
else
fragoff = 0;
dlen += fragoff;
for(; fragoff < dlen; fragoff += seglen) {
nb = allocb(hlen+seglen);
feh = (Ip4hdr*)nb->rp;
memmove(nb->wp, eh, hlen);
nb->wp += hlen;
if((fragoff + seglen) >= dlen) {
seglen = dlen - fragoff;
hnputs(feh->frag, fragoff>>3);
}
else
hnputs(feh->frag, (fragoff>>3)|IP_MF);
hnputs(feh->length, seglen + hlen);
hnputs(feh->id, lid);
/* Copy up the data area */
chunk = seglen;
while(chunk) {
if(xp == nil) {
ip->stats[OutDiscards]++;
ip->stats[FragFails]++;
freeblist(nb);
netlog(f, Logip, "xp == nil: chunk %d\n", chunk);
goto raise;
}
blklen = chunk;
if(BLEN(xp) < chunk)
blklen = BLEN(xp);
memmove(nb->wp, xp->rp, blklen);
nb->wp += blklen;
xp->rp += blklen;
chunk -= blklen;
if(xp->rp == xp->wp)
xp = xp->next;
}
feh->cksum[0] = 0;
feh->cksum[1] = 0;
hnputs(feh->cksum, ipcsum(&feh->vihl));
ipifcoput(ifc, nb, V4, gate, rh);
ip->stats[FragCreates]++;
}
ip->stats[FragOKs]++;
raise:
runlock(ifc);
poperror();
free:
freeblist(bp);
return rv;
}
void
ipiput4(Fs *f, Ipifc *ifc, Block *bp)
{
int hl, len, hop;
uchar v6dst[IPaddrlen];
ushort frag;
Ip4hdr *h;
Proto *p;
IP *ip;
if((bp->rp[0]&0xF0) != IP_VER4) {
ipiput6(f, ifc, bp);
return;
}
ip = f->ip;
ip->stats[InReceives]++;
/*
* Ensure we have all the header info in the first
* block. Make life easier for other protocols by
* collecting up to the first 64 bytes in the first block.
*/
if(BLEN(bp) < 64) {
hl = blocklen(bp);
if(hl < IP4HDR)
hl = IP4HDR;
if(hl > 64)
hl = 64;
bp = pullupblock(bp, hl);
if(bp == nil)
return;
}
h = (Ip4hdr*)bp->rp;
hl = (h->vihl & 0xF)<<2;
if(hl < IP4HDR || hl > BLEN(bp)) {
ip->stats[InHdrErrors]++;
netlog(f, Logip, "%V -> %V: bad ip header length: %d\n", h->src, h->dst, hl);
goto drop;
}
if((bp->flag & Bipck) == 0 && ipcsum(&h->vihl)) {
ip->stats[InHdrErrors]++;
netlog(f, Logip, "%V -> %V: bad ip header checksum\n", h->src, h->dst);
goto drop;
}
len = nhgets(h->length);
if(len < hl || (bp = trimblock(bp, 0, len)) == nil){
ip->stats[InHdrErrors]++;
netlog(f, Logip, "%V -> %V: bogus packet length: %d\n", h->src, h->dst, len);
if(bp != nil)
goto drop;
return;
}
h = (Ip4hdr*)bp->rp;
/* route */
v4tov6(v6dst, h->dst);
if(!ipforme(f, v6dst)) {
Routehint rh;
Route *r;
Ipifc *nifc;
if(!ip->iprouting)
goto drop;
/* don't forward to source's network */
rh.r = nil;
rh.a = nil;
r = v4lookup(f, h->dst, h->src, &rh);
if(r == nil || (nifc = r->ifc) == nil
|| (nifc == ifc && !ifc->reflect)){
ip->stats[OutDiscards]++;
goto drop;
}
/* don't forward if packet has timed out */
hop = h->ttl;
if(hop <= 1) {
ip->stats[InHdrErrors]++;
icmpttlexceeded(f, ifc, bp);
goto drop;
}
if(r->type & Rtrans) {
p = Fsrcvpcolx(f, h->proto);
if(p == nil || p->forward == nil){
ip->stats[OutDiscards]++;
goto drop;
}
if(hl > IP4HDR) {
hl -= IP4HDR;
len -= hl;
bp->rp += hl;
memmove(bp->rp, h, IP4HDR);
h = (Ip4hdr*)bp->rp;
h->vihl = IP_VER4|IP_HLEN4;
hnputs(h->length, len);
}
frag = nhgets(h->frag);
if(frag & (IP_MF|IP_FO)) {
bp = ip4reassemble(ip, frag, bp);
if(bp == nil)
return;
}
bp = (*p->forward)(p, bp, r);
if(bp == nil)
return;
h = (Ip4hdr*)bp->rp;
} else if(nifc->reassemble) {
/* reassemble as the interface expects it */
frag = nhgets(h->frag);
if(frag & (IP_MF|IP_FO)) {
bp = ip4reassemble(ip, frag, bp);
if(bp == nil)
return;
h = (Ip4hdr*)bp->rp;
}
}
ip->stats[ForwDatagrams]++;
ipoput4(f, bp, ifc, hop - 1, h->tos, &rh);
return;
}
/* If this is not routed strip off the options */
if(hl > IP4HDR) {
hl -= IP4HDR;
len -= hl;
bp->rp += hl;
memmove(bp->rp, h, IP4HDR);
h = (Ip4hdr*)bp->rp;
h->vihl = IP_VER4|IP_HLEN4;
hnputs(h->length, len);
}
frag = nhgets(h->frag);
if(frag & (IP_MF|IP_FO)) {
bp = ip4reassemble(ip, frag, bp);
if(bp == nil)
return;
h = (Ip4hdr*)bp->rp;
}
p = Fsrcvpcol(f, h->proto);
if(p != nil && p->rcv != nil) {
ip->stats[InDelivers]++;
(*p->rcv)(p, ifc, bp);
return;
}
ip->stats[InDiscards]++;
ip->stats[InUnknownProtos]++;
drop:
freeblist(bp);
}
int
ipstats(Fs *f, char *buf, int len)
{
IP *ip;
char *p, *e;
int i;
ip = f->ip;
p = buf;
e = p+len;
for(i = 0; i < Nipstats; i++)
p = seprint(p, e, "%s: %llud\n", statnames[i], ip->stats[i]);
return p - buf;
}
static Block*
ip4reassemble(IP *ip, int offset, Block *bp)
{
int ovlap, fragsize, len;
ulong src, dst;
ushort id;
Block *bl, **l, *prev;
Fragment4 *f, *fnext;
Ipfrag *fp, *fq;
Ip4hdr *ih;
/*
* block lists are too hard, concatblock into a single block
*/
bp = concatblock(bp);
ih = (Ip4hdr*)bp->rp;
src = nhgetl(ih->src);
dst = nhgetl(ih->dst);
id = nhgets(ih->id);
fragsize = BLEN(bp) - ((ih->vihl&0xF)<<2);
qlock(&ip->fraglock4);
/*
* find a reassembly queue for this fragment
*/
for(f = ip->flisthead4; f != nil; f = fnext){
fnext = f->next; /* because ipfragfree4 changes the list */
if(f->id == id && f->src == src && f->dst == dst)
break;
if(f->age < NOW){
ip->stats[ReasmTimeout]++;
ipfragfree4(ip, f);
}
}
/*
* if this isn't a fragmented packet, accept it
* and get rid of any fragments that might go
* with it.
*/
if((offset & (IP_MF|IP_FO)) == 0) {
if(f != nil) {
ip->stats[ReasmFails]++;
ipfragfree4(ip, f);
}
qunlock(&ip->fraglock4);
return bp;
}
if(bp->base+IPFRAGSZ > bp->rp){
bp = padblock(bp, IPFRAGSZ);
bp->rp += IPFRAGSZ;
}
fp = (Ipfrag*)bp->base;
fp->foff = (offset & IP_FO)<<3;
fp->flen = fragsize;
/* First fragment allocates a reassembly queue */
if(f == nil) {
f = ipfragallo4(ip);
f->id = id;
f->src = src;
f->dst = dst;
f->blist = bp;
ip->stats[ReasmReqds]++;
qunlock(&ip->fraglock4);
return nil;
}
/*
* find the new fragment's position in the queue
*/
prev = nil;
l = &f->blist;
bl = f->blist;
while(bl != nil && fp->foff > ((Ipfrag*)bl->base)->foff) {
prev = bl;
l = &bl->next;
bl = bl->next;
}
/* Check overlap of a previous fragment - trim away as necessary */
if(prev != nil) {
fq = (Ipfrag*)prev->base;
ovlap = fq->foff + fq->flen - fp->foff;
if(ovlap > 0) {
if(ovlap >= fp->flen) {
qunlock(&ip->fraglock4);
freeb(bp);
return nil;
}
fq->flen -= ovlap;
}
}
/* Link onto assembly queue */
bp->next = *l;
*l = bp;
/* Check to see if succeeding segments overlap */
if(bp->next != nil) {
l = &bp->next;
offset = fp->foff + fp->flen;
/* Take completely covered segments out */
while((bl = *l) != nil) {
fq = (Ipfrag*)bl->base;
ovlap = offset - fq->foff;
if(ovlap <= 0)
break;
if(ovlap < fq->flen) {
/* move up ip header */
memmove(bl->rp + ovlap, bl->rp, BLEN(bl) - fq->flen);
bl->rp += ovlap;
fq->flen -= ovlap;
fq->foff += ovlap;
break;
}
*l = bl->next;
bl->next = nil;
freeb(bl);
}
}
/*
* look for a complete packet. if we get to a fragment
* without IP_MF set, we're done.
*/
offset = 0;
for(bl = f->blist; bl != nil; bl = bl->next, offset += fp->flen) {
fp = (Ipfrag*)bl->base;
if(fp->foff != offset)
break;
ih = (Ip4hdr*)bl->rp;
if(ih->frag[0]&(IP_MF>>8))
continue;
bl = f->blist;
len = BLEN(bl);
/*
* Pullup all the fragment headers and
* return a complete packet
*/
for(bl = bl->next; bl != nil && len < IP_MAX; bl = bl->next) {
fq = (Ipfrag*)bl->base;
fragsize = fq->flen;
bl->rp = bl->wp - fragsize;
len += fragsize;
}
if(len >= IP_MAX){
ipfragfree4(ip, f);
ip->stats[ReasmFails]++;
qunlock(&ip->fraglock4);
return nil;
}
bl = f->blist;
f->blist = nil;
ipfragfree4(ip, f);
ih = (Ip4hdr*)bl->rp;
ih->frag[0] = 0;
ih->frag[1] = 0;
hnputs(ih->length, len);
ip->stats[ReasmOKs]++;
qunlock(&ip->fraglock4);
return bl;
}
qunlock(&ip->fraglock4);
return nil;
}
/*
* ipfragfree4 - Free a list of fragments - assume hold fraglock4
*/
static void
ipfragfree4(IP *ip, Fragment4 *frag)
{
Fragment4 *fl, **l;
if(frag->blist != nil)
freeblist(frag->blist);
frag->blist = nil;
frag->id = 0;
frag->src = 0;
frag->dst = 0;
l = &ip->flisthead4;
for(fl = *l; fl != nil; fl = fl->next) {
if(fl == frag) {
*l = frag->next;
break;
}
l = &fl->next;
}
frag->next = ip->fragfree4;
ip->fragfree4 = frag;
}
/*
* ipfragallo4 - allocate a reassembly queue - assume hold fraglock4
*/
static Fragment4*
ipfragallo4(IP *ip)
{
Fragment4 *f;
while(ip->fragfree4 == nil) {
/* free last entry on fraglist */
for(f = ip->flisthead4; f->next != nil; f = f->next)
;
ipfragfree4(ip, f);
}
f = ip->fragfree4;
ip->fragfree4 = f->next;
f->next = ip->flisthead4;
ip->flisthead4 = f;
f->age = NOW + 30000;
return f;
}
ushort
ipcsum(uchar *addr)
{
int len;
ulong sum;
sum = 0;
len = (addr[0]&0xf)<<2;
while(len > 0) {
sum += addr[0]<<8 | addr[1] ;
len -= 2;
addr += 2;
}
sum = (sum & 0xffff) + (sum >> 16);
sum = (sum & 0xffff) + (sum >> 16);
return (sum^0xffff);
}