ref: d916a4c3823f55227ffae35738c2497256e307b5
dir: /os/ip/ipv6.c/
#include "u.h"
#include "../port/lib.h"
#include "mem.h"
#include "dat.h"
#include "fns.h"
#include "../port/error.h"
#include "ip.h"
#include "ipv6.h"
enum
{
IP4HDR = 20, /* sizeof(Ip4hdr) */
IP6HDR = 40, /* sizeof(Ip6hdr) */
IP_HLEN4 = 0x05, /* Header length in words */
IP_DF = 0x4000, /* Don't fragment */
IP_MF = 0x2000, /* More fragments */
IP6FHDR = 8, /* sizeof(Fraghdr6) */
IP_MAX = (32*1024), /* Maximum Internet packet size */
};
#define IPV6CLASS(hdr) ((hdr->vcf[0]&0x0F)<<2 | (hdr->vcf[1]&0xF0)>>2)
#define BLKIPVER(xp) (((Ip6hdr*)((xp)->rp))->vcf[0]&0xF0)
/*
* This sleazy macro is stolen shamelessly from ip.c, see comment there.
*/
#define BKFG(xp) ((Ipfrag*)((xp)->base))
typedef struct IP IP;
typedef struct Fragment4 Fragment4;
typedef struct Fragment6 Fragment6;
typedef struct Ipfrag Ipfrag;
Block* ip6reassemble(IP*, int, Block*, Ip6hdr*);
void ipfragfree6(IP*, Fragment6*);
Fragment6* ipfragallo6(IP*);
static Block* procxtns(IP *ip, Block *bp, int doreasm);
int unfraglen(Block *bp, uchar *nexthdr, int setfh);
Block* procopts(Block *bp);
/* MIB II counters */
enum
{
Forwarding,
DefaultTTL,
InReceives,
InHdrErrors,
InAddrErrors,
ForwDatagrams,
InUnknownProtos,
InDiscards,
InDelivers,
OutRequests,
OutDiscards,
OutNoRoutes,
ReasmTimeout,
ReasmReqds,
ReasmOKs,
ReasmFails,
FragOKs,
FragFails,
FragCreates,
Nstats,
};
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",
};
struct Fragment4
{
Block* blist;
Fragment4* next;
ulong src;
ulong dst;
ushort id;
ulong age;
};
struct Fragment6
{
Block* blist;
Fragment6* next;
uchar src[IPaddrlen];
uchar dst[IPaddrlen];
uint id;
ulong age;
};
struct Ipfrag
{
ushort foff;
ushort flen;
};
/* an instance of IP */
struct IP
{
ulong stats[Nstats];
QLock fraglock4;
Fragment4* flisthead4;
Fragment4* fragfree4;
Ref id4;
QLock fraglock6;
Fragment6* flisthead6;
Fragment6* fragfree6;
Ref id6;
int iprouting; /* true if we route like a gateway */
};
int
ipoput6(Fs *f, Block *bp, int gating, int ttl, int tos, Conv *c)
{
int tentative;
Ipifc *ifc;
uchar *gate, nexthdr;
Ip6hdr *eh;
int medialen, len, chunk, uflen, flen, seglen, lid, offset, fragoff, morefrags, blklen;
Route *r, *sr;
Fraghdr6 fraghdr;
Block *xp, *nb;
IP *ip;
int rv = 0;
ip = f->ip;
/* Fill out the ip header */
eh = (Ip6hdr*)(bp->rp);
ip->stats[OutRequests]++;
/* Number of uchars in data and ip header to write */
len = blocklen(bp);
tentative = iptentative(f, eh->src);
if(tentative){
netlog(f, Logip, "reject tx of packet with tentative src address\n");
goto free;
}
if(gating){
chunk = nhgets(eh->ploadlen);
if(chunk > len){
ip->stats[OutDiscards]++;
netlog(f, Logip, "short gated packet\n");
goto free;
}
if(chunk + IPV6HDR_LEN < len)
len = chunk + IPV6HDR_LEN;
}
if(len >= IP_MAX){
// print("len > IP_MAX, free\n");
ip->stats[OutDiscards]++;
netlog(f, Logip, "exceeded ip max size %I\n", eh->dst);
goto free;
}
r = v6lookup(f, eh->dst, c);
if(r == nil){
// print("no route for %I, src %I free\n", eh->dst, eh->src);
ip->stats[OutNoRoutes]++;
netlog(f, Logip, "no interface %I\n", eh->dst);
rv = -1;
goto free;
}
ifc = r->ifc;
if(r->type & (Rifc|Runi))
gate = eh->dst;
else
if(r->type & (Rbcast|Rmulti)) {
gate = eh->dst;
sr = v6lookup(f, eh->src, nil);
if(sr != nil && (sr->type & Runi))
ifc = sr->ifc;
}
else
gate = r->v6.gate;
if(!gating)
eh->vcf[0] = IP_VER6;
eh->ttl = ttl;
if(!gating) {
eh->vcf[0] |= (tos >> 4);
eh->vcf[1] = (tos << 4);
}
if(!canrlock(ifc)) {
goto free;
}
if(waserror()){
runlock(ifc);
nexterror();
}
if(ifc->m == nil) {
goto raise;
}
/* If we dont need to fragment just send it */
medialen = ifc->maxtu - ifc->m->hsize;
if(len <= medialen) {
hnputs(eh->ploadlen, len-IPV6HDR_LEN);
ifc->m->bwrite(ifc, bp, V6, gate);
runlock(ifc);
poperror();
return 0;
}
if(gating)
if(ifc->reassemble <= 0) {
/* v6 intermediate nodes are not supposed to fragment pkts;
we fragment if ifc->reassemble is turned on; an exception
needed for nat.
*/
ip->stats[OutDiscards]++;
icmppkttoobig6(f, ifc, bp);
netlog(f, Logip, "%I: gated pkts not fragmented\n", eh->dst);
goto raise;
}
/* start v6 fragmentation */
uflen = unfraglen(bp, &nexthdr, 1);
if(uflen > medialen) {
ip->stats[FragFails]++;
ip->stats[OutDiscards]++;
netlog(f, Logip, "%I: unfragmentable part too big\n", eh->dst);
goto raise;
}
flen = len - uflen;
seglen = (medialen - (uflen + IP6FHDR)) & ~7;
if(seglen < 8) {
ip->stats[FragFails]++;
ip->stats[OutDiscards]++;
netlog(f, Logip, "%I: seglen < 8\n", eh->dst);
goto raise;
}
lid = incref(&ip->id6);
fraghdr.nexthdr = nexthdr;
fraghdr.res = 0;
hnputl(fraghdr.id, lid);
xp = bp;
offset = uflen;
while (xp != nil && offset && offset >= BLEN(xp)) {
offset -= BLEN(xp);
xp = xp->next;
}
xp->rp += offset;
fragoff = 0;
morefrags = 1;
for(; fragoff < flen; fragoff += seglen) {
nb = allocb(uflen + IP6FHDR + seglen);
if(fragoff + seglen >= flen) {
seglen = flen - fragoff;
morefrags = 0;
}
hnputs(eh->ploadlen, seglen+IP6FHDR);
memmove(nb->wp, eh, uflen);
nb->wp += uflen;
hnputs(fraghdr.offsetRM, fragoff); // last 3 bits must be 0
fraghdr.offsetRM[1] |= morefrags;
memmove(nb->wp, &fraghdr, IP6FHDR);
nb->wp += IP6FHDR;
/* Copy data */
chunk = seglen;
while (chunk) {
if(!xp) {
ip->stats[OutDiscards]++;
ip->stats[FragFails]++;
freeblist(nb);
netlog(f, Logip, "!xp: chunk in v6%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;
}
ifc->m->bwrite(ifc, nb, V6, gate);
ip->stats[FragCreates]++;
}
ip->stats[FragOKs]++;
raise:
runlock(ifc);
poperror();
free:
freeblist(bp);
return rv;
}
void
ipiput6(Fs *f, Ipifc *ifc, Block *bp)
{
int hl;
int hop, tos;
uchar proto;
Ip6hdr *h;
Proto *p;
int notforme;
int tentative;
uchar v6dst[IPaddrlen];
IP *ip;
Route *r, *sr;
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 < IP6HDR)
hl = IP6HDR;
if(hl > 64)
hl = 64;
bp = pullupblock(bp, hl);
if(bp == nil)
return;
}
h = (Ip6hdr *)(bp->rp);
memmove(&v6dst[0], &(h->dst)[0], IPaddrlen);
notforme = ipforme(f, v6dst) == 0;
tentative = iptentative(f, v6dst);
if(tentative && (h->proto != ICMPv6)) {
print("tentative addr, drop\n");
freeblist(bp);
return;
}
/* Check header version */
if(BLKIPVER(bp) != IP_VER6) {
ip->stats[InHdrErrors]++;
netlog(f, Logip, "ip: bad version %ux\n", (h->vcf[0]&0xF0)>>2);
freeblist(bp);
return;
}
/* route */
if(notforme) {
if(!ip->iprouting){
freeb(bp);
return;
}
/* don't forward to source's network */
sr = v6lookup(f, h->src, nil);
r = v6lookup(f, h->dst, nil);
if(r == nil || sr == r){
ip->stats[OutDiscards]++;
freeblist(bp);
return;
}
/* don't forward if packet has timed out */
hop = h->ttl;
if(hop < 1) {
ip->stats[InHdrErrors]++;
icmpttlexceeded6(f, ifc, bp);
freeblist(bp);
return;
}
/* process headers & reassemble if the interface expects it */
bp = procxtns(ip, bp, r->ifc->reassemble);
if(bp == nil)
return;
ip->stats[ForwDatagrams]++;
h = (Ip6hdr *) (bp->rp);
tos = IPV6CLASS(h);
hop = h->ttl;
ipoput6(f, bp, 1, hop-1, tos, nil);
return;
}
/* reassemble & process headers if needed */
bp = procxtns(ip, bp, 1);
if(bp == nil)
return;
h = (Ip6hdr *) (bp->rp);
proto = h->proto;
p = Fsrcvpcol(f, proto);
if(p != nil && p->rcv != nil) {
ip->stats[InDelivers]++;
(*p->rcv)(p, ifc, bp);
return;
}
ip->stats[InDiscards]++;
ip->stats[InUnknownProtos]++;
freeblist(bp);
}
/*
* ipfragfree6 - copied from ipfragfree4 - assume hold fraglock6
*/
void
ipfragfree6(IP *ip, Fragment6 *frag)
{
Fragment6 *fl, **l;
if(frag->blist)
freeblist(frag->blist);
memset(frag->src, 0, IPaddrlen);
frag->id = 0;
frag->blist = nil;
l = &ip->flisthead6;
for(fl = *l; fl; fl = fl->next) {
if(fl == frag) {
*l = frag->next;
break;
}
l = &fl->next;
}
frag->next = ip->fragfree6;
ip->fragfree6 = frag;
}
/*
* ipfragallo6 - copied from ipfragalloc4
*/
Fragment6*
ipfragallo6(IP *ip)
{
Fragment6 *f;
while(ip->fragfree6 == nil) {
/* free last entry on fraglist */
for(f = ip->flisthead6; f->next; f = f->next)
;
ipfragfree6(ip, f);
}
f = ip->fragfree6;
ip->fragfree6 = f->next;
f->next = ip->flisthead6;
ip->flisthead6 = f;
f->age = NOW + 30000;
return f;
}
static Block*
procxtns(IP *ip, Block *bp, int doreasm) {
int offset;
uchar proto;
Ip6hdr *h;
h = (Ip6hdr *) (bp->rp);
offset = unfraglen(bp, &proto, 0);
if((proto == FH) && (doreasm != 0)) {
bp = ip6reassemble(ip, offset, bp, h);
if(bp == nil)
return nil;
offset = unfraglen(bp, &proto, 0);
}
if(proto == DOH || offset > IP6HDR)
bp = procopts(bp);
return bp;
}
/* returns length of "Unfragmentable part", i.e., sum of lengths of ipv6 hdr,
* hop-by-hop & routing headers if present; *nexthdr is set to nexthdr value
* of the last header in the "Unfragmentable part"; if setfh != 0, nexthdr
* field of the last header in the "Unfragmentable part" is set to FH.
*/
int
unfraglen(Block *bp, uchar *nexthdr, int setfh)
{
uchar *p, *q;
int ufl, hs;
p = bp->rp;
q = p+6; /* proto, = p+sizeof(Ip6hdr.vcf)+sizeof(Ip6hdr.ploadlen) */
*nexthdr = *q;
ufl = IP6HDR;
p += ufl;
for(;;) {
if(*nexthdr == HBH || *nexthdr == RH) {
*nexthdr = *p;
hs = ((int)*(p+1) + 1) * 8;
ufl += hs;
q = p;
p += hs;
}
else
break;
}
if(*nexthdr == FH)
*q = *p;
if(setfh)
*q = FH;
return ufl;
}
Block*
procopts(Block *bp)
{
return bp;
}
Block*
ip6reassemble(IP* ip, int uflen, Block* bp, Ip6hdr* ih)
{
int fend, offset;
uint id;
Fragment6 *f, *fnext;
Fraghdr6 *fraghdr;
uchar src[IPaddrlen], dst[IPaddrlen];
Block *bl, **l, *last, *prev;
int ovlap, len, fragsize, pktposn;
fraghdr = (Fraghdr6 *) (bp->rp + uflen);
memmove(src, ih->src, IPaddrlen);
memmove(dst, ih->dst, IPaddrlen);
id = nhgetl(fraghdr->id);
offset = nhgets(fraghdr->offsetRM) & ~7;
/*
* block lists are too hard, pullupblock into a single block
*/
if(bp->next){
bp = pullupblock(bp, blocklen(bp));
ih = (Ip6hdr *)(bp->rp);
}
qlock(&ip->fraglock6);
/*
* find a reassembly queue for this fragment
*/
for(f = ip->flisthead6; f; f = fnext){
fnext = f->next;
if(ipcmp(f->src, src)==0 && ipcmp(f->dst, dst)==0 && f->id == id)
break;
if(f->age < NOW){
ip->stats[ReasmTimeout]++;
ipfragfree6(ip, f);
}
}
/*
* if this isn't a fragmented packet, accept it
* and get rid of any fragments that might go
* with it.
*/
if(nhgets(fraghdr->offsetRM)==0) { // first frag is also the last
if(f != nil) {
ipfragfree6(ip, f);
ip->stats[ReasmFails]++;
}
qunlock(&ip->fraglock6);
return bp;
}
if(bp->base+sizeof(Ipfrag) >= bp->rp){
bp = padblock(bp, sizeof(Ipfrag));
bp->rp += sizeof(Ipfrag);
}
BKFG(bp)->foff = offset;
BKFG(bp)->flen = nhgets(ih->ploadlen) + IP6HDR - uflen - IP6FHDR;
/* First fragment allocates a reassembly queue */
if(f == nil) {
f = ipfragallo6(ip);
f->id = id;
memmove(f->src, src, IPaddrlen);
memmove(f->dst, dst, IPaddrlen);
f->blist = bp;
qunlock(&ip->fraglock6);
ip->stats[ReasmReqds]++;
return nil;
}
/*
* find the new fragment's position in the queue
*/
prev = nil;
l = &f->blist;
bl = f->blist;
while(bl != nil && BKFG(bp)->foff > BKFG(bl)->foff) {
prev = bl;
l = &bl->next;
bl = bl->next;
}
/* Check overlap of a previous fragment - trim away as necessary */
if(prev) {
ovlap = BKFG(prev)->foff + BKFG(prev)->flen - BKFG(bp)->foff;
if(ovlap > 0) {
if(ovlap >= BKFG(bp)->flen) {
freeblist(bp);
qunlock(&ip->fraglock6);
return nil;
}
BKFG(prev)->flen -= ovlap;
}
}
/* Link onto assembly queue */
bp->next = *l;
*l = bp;
/* Check to see if succeeding segments overlap */
if(bp->next) {
l = &bp->next;
fend = BKFG(bp)->foff + BKFG(bp)->flen;
/* Take completely covered segments out */
while(*l) {
ovlap = fend - BKFG(*l)->foff;
if(ovlap <= 0)
break;
if(ovlap < BKFG(*l)->flen) {
BKFG(*l)->flen -= ovlap;
BKFG(*l)->foff += ovlap;
/* move up ih hdrs */
memmove((*l)->rp + ovlap, (*l)->rp, uflen);
(*l)->rp += ovlap;
break;
}
last = (*l)->next;
(*l)->next = nil;
freeblist(*l);
*l = last;
}
}
/*
* look for a complete packet. if we get to a fragment
* with the trailing bit of fraghdr->offsetRM[1] set, we're done.
*/
pktposn = 0;
for(bl = f->blist; bl; bl = bl->next) {
if(BKFG(bl)->foff != pktposn)
break;
fraghdr = (Fraghdr6 *) (bl->rp + uflen);
if((fraghdr->offsetRM[1] & 1) == 0) {
bl = f->blist;
/* get rid of frag header in first fragment */
memmove(bl->rp + IP6FHDR, bl->rp, uflen);
bl->rp += IP6FHDR;
len = nhgets(((Ip6hdr*)(bl->rp))->ploadlen) - IP6FHDR;
bl->wp = bl->rp + len + IP6HDR;
/* Pullup all the fragment headers and
* return a complete packet
*/
for(bl = bl->next; bl; bl = bl->next) {
fragsize = BKFG(bl)->flen;
len += fragsize;
bl->rp += uflen + IP6FHDR;
bl->wp = bl->rp + fragsize;
}
bl = f->blist;
f->blist = nil;
ipfragfree6(ip, f);
ih = (Ip6hdr*)(bl->rp);
hnputs(ih->ploadlen, len);
qunlock(&ip->fraglock6);
ip->stats[ReasmOKs]++;
return bl;
}
pktposn += BKFG(bl)->flen;
}
qunlock(&ip->fraglock6);
return nil;
}