![cinap_lenrek](/assets/img/avatar_default.png)
the convention for Dev.bwrite() is that it accepts a *single* block, and not a block chain. so we never have concatblock here. to keep stuff consistent, we also guarantee thet Medium.bwrite() will get a *single* block passed as well, as the callers are few in number.
622 lines
12 KiB
C
622 lines
12 KiB
C
#include "u.h"
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#include "../port/lib.h"
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#include "mem.h"
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#include "dat.h"
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#include "fns.h"
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#include "../port/error.h"
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#include "ip.h"
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#include "ipv6.h"
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enum
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{
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IP6FHDR = 8, /* sizeof(Fraghdr6) */
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};
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#define IPV6CLASS(hdr) (((hdr)->vcf[0]&0x0F)<<2 | ((hdr)->vcf[1]&0xF0)>>2)
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#define BLKIPVER(xp) (((Ip6hdr*)((xp)->rp))->vcf[0] & 0xF0)
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/*
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* This sleazy macro is stolen shamelessly from ip.c, see comment there.
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*/
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#define BKFG(xp) ((Ipfrag*)((xp)->base))
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Block* ip6reassemble(IP*, int, Block*, Ip6hdr*);
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Fragment6* ipfragallo6(IP*);
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void ipfragfree6(IP*, Fragment6*);
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Block* procopts(Block *bp);
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static Block* procxtns(IP *ip, Block *bp, int doreasm);
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int unfraglen(Block *bp, uchar *nexthdr, int setfh);
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int
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ipoput6(Fs *f, Block *bp, int gating, int ttl, int tos, Conv *c)
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{
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int medialen, len, chunk, uflen, flen, seglen, lid, offset, fragoff;
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int morefrags, blklen, rv = 0, tentative;
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uchar *gate, nexthdr;
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Block *xp, *nb;
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Fraghdr6 fraghdr;
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IP *ip;
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Ip6hdr *eh;
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Ipifc *ifc;
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Route *r, *sr;
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ip = f->ip;
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/* Fill out the ip header */
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eh = (Ip6hdr*)(bp->rp);
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ip->stats[OutRequests]++;
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/* Number of uchars in data and ip header to write */
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len = blocklen(bp);
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tentative = iptentative(f, eh->src);
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if(tentative){
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netlog(f, Logip, "reject tx of packet with tentative src address %I\n",
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eh->src);
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goto free;
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}
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if(gating){
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chunk = nhgets(eh->ploadlen);
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if(chunk > len){
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ip->stats[OutDiscards]++;
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netlog(f, Logip, "short gated packet\n");
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goto free;
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}
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if(chunk + IP6HDR < len)
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len = chunk + IP6HDR;
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}
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if(len >= IP_MAX){
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ip->stats[OutDiscards]++;
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netlog(f, Logip, "exceeded ip max size %I\n", eh->dst);
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goto free;
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}
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r = v6lookup(f, eh->dst, c);
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if(r == nil){
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// print("no route for %I, src %I free\n", eh->dst, eh->src);
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ip->stats[OutNoRoutes]++;
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netlog(f, Logip, "no interface %I\n", eh->dst);
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rv = -1;
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goto free;
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}
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ifc = r->ifc;
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if(r->type & (Rifc|Runi))
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gate = eh->dst;
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else if(r->type & (Rbcast|Rmulti)) {
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gate = eh->dst;
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sr = v6lookup(f, eh->src, nil);
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if(sr && (sr->type & Runi))
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ifc = sr->ifc;
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}
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else
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gate = r->v6.gate;
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if(!gating)
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eh->vcf[0] = IP_VER6;
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eh->ttl = ttl;
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if(!gating) {
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eh->vcf[0] |= tos >> 4;
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eh->vcf[1] = tos << 4;
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}
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if(!canrlock(ifc))
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goto free;
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if(waserror()){
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runlock(ifc);
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nexterror();
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}
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if(ifc->m == nil)
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goto raise;
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/* If we dont need to fragment just send it */
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medialen = ifc->maxtu - ifc->m->hsize;
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if(len <= medialen) {
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hnputs(eh->ploadlen, len - IP6HDR);
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ifc->m->bwrite(ifc, concatblock(bp), V6, gate);
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runlock(ifc);
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poperror();
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return 0;
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}
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if(gating && ifc->reassemble <= 0) {
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/*
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* v6 intermediate nodes are not supposed to fragment pkts;
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* we fragment if ifc->reassemble is turned on; an exception
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* needed for nat.
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*/
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ip->stats[OutDiscards]++;
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icmppkttoobig6(f, ifc, bp);
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netlog(f, Logip, "%I: gated pkts not fragmented\n", eh->dst);
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goto raise;
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}
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/* start v6 fragmentation */
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uflen = unfraglen(bp, &nexthdr, 1);
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if(uflen > medialen) {
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ip->stats[FragFails]++;
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ip->stats[OutDiscards]++;
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netlog(f, Logip, "%I: unfragmentable part too big\n", eh->dst);
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goto raise;
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}
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flen = len - uflen;
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seglen = (medialen - (uflen + IP6FHDR)) & ~7;
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if(seglen < 8) {
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ip->stats[FragFails]++;
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ip->stats[OutDiscards]++;
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netlog(f, Logip, "%I: seglen < 8\n", eh->dst);
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goto raise;
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}
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lid = incref(&ip->id6);
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fraghdr.nexthdr = nexthdr;
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fraghdr.res = 0;
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hnputl(fraghdr.id, lid);
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xp = bp;
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offset = uflen;
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while (offset && offset >= BLEN(xp)) {
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offset -= BLEN(xp);
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xp = xp->next;
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}
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xp->rp += offset;
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fragoff = 0;
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morefrags = 1;
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for(; fragoff < flen; fragoff += seglen) {
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nb = allocb(uflen + IP6FHDR + seglen);
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if(fragoff + seglen >= flen) {
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seglen = flen - fragoff;
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morefrags = 0;
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}
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hnputs(eh->ploadlen, seglen+IP6FHDR);
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memmove(nb->wp, eh, uflen);
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nb->wp += uflen;
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hnputs(fraghdr.offsetRM, fragoff); /* last 3 bits must be 0 */
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fraghdr.offsetRM[1] |= morefrags;
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memmove(nb->wp, &fraghdr, IP6FHDR);
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nb->wp += IP6FHDR;
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/* Copy data */
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chunk = seglen;
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while (chunk) {
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if(!xp) {
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ip->stats[OutDiscards]++;
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ip->stats[FragFails]++;
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freeblist(nb);
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netlog(f, Logip, "!xp: chunk in v6%d\n", chunk);
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goto raise;
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}
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blklen = chunk;
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if(BLEN(xp) < chunk)
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blklen = BLEN(xp);
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memmove(nb->wp, xp->rp, blklen);
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nb->wp += blklen;
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xp->rp += blklen;
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chunk -= blklen;
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if(xp->rp == xp->wp)
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xp = xp->next;
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}
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ifc->m->bwrite(ifc, nb, V6, gate);
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ip->stats[FragCreates]++;
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}
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ip->stats[FragOKs]++;
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raise:
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runlock(ifc);
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poperror();
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free:
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freeblist(bp);
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return rv;
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}
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void
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ipiput6(Fs *f, Ipifc *ifc, Block *bp)
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{
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int hl, hop, tos, notforme, tentative;
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uchar proto;
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uchar v6dst[IPaddrlen];
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IP *ip;
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Ip6hdr *h;
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Proto *p;
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Route *r, *sr;
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ip = f->ip;
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ip->stats[InReceives]++;
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/*
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* Ensure we have all the header info in the first
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* block. Make life easier for other protocols by
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* collecting up to the first 64 bytes in the first block.
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*/
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if(BLEN(bp) < 64) {
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hl = blocklen(bp);
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if(hl < IP6HDR)
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hl = IP6HDR;
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if(hl > 64)
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hl = 64;
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bp = pullupblock(bp, hl);
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if(bp == nil)
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return;
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}
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h = (Ip6hdr *)bp->rp;
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memmove(&v6dst[0], &h->dst[0], IPaddrlen);
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notforme = ipforme(f, v6dst) == 0;
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tentative = iptentative(f, v6dst);
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if(tentative && h->proto != ICMPv6) {
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print("tentative addr, drop\n");
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freeblist(bp);
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return;
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}
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/* Check header version */
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if(BLKIPVER(bp) != IP_VER6) {
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ip->stats[InHdrErrors]++;
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netlog(f, Logip, "ip: bad version %ux\n", (h->vcf[0]&0xF0)>>2);
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freeblist(bp);
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return;
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}
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/* route */
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if(notforme) {
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if(!ip->iprouting){
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freeblist(bp);
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return;
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}
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/* don't forward to link-local destinations */
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if(islinklocal(h->dst) ||
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(isv6mcast(h->dst) && (h->dst[1]&0xF) <= Link_local_scop)){
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ip->stats[OutDiscards]++;
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freeblist(bp);
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return;
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}
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/* don't forward to source's network */
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sr = v6lookup(f, h->src, nil);
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r = v6lookup(f, h->dst, nil);
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if(r == nil || sr == r){
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ip->stats[OutDiscards]++;
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freeblist(bp);
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return;
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}
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/* don't forward if packet has timed out */
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hop = h->ttl;
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if(hop < 1) {
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ip->stats[InHdrErrors]++;
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icmpttlexceeded6(f, ifc, bp);
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freeblist(bp);
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return;
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}
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/* process headers & reassemble if the interface expects it */
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bp = procxtns(ip, bp, r->ifc->reassemble);
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if(bp == nil)
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return;
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ip->stats[ForwDatagrams]++;
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h = (Ip6hdr *)bp->rp;
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tos = IPV6CLASS(h);
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hop = h->ttl;
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ipoput6(f, bp, 1, hop-1, tos, nil);
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return;
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}
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/* reassemble & process headers if needed */
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bp = procxtns(ip, bp, 1);
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if(bp == nil)
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return;
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h = (Ip6hdr *) (bp->rp);
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proto = h->proto;
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p = Fsrcvpcol(f, proto);
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if(p && p->rcv) {
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ip->stats[InDelivers]++;
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(*p->rcv)(p, ifc, bp);
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return;
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}
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ip->stats[InDiscards]++;
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ip->stats[InUnknownProtos]++;
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freeblist(bp);
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}
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/*
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* ipfragfree6 - copied from ipfragfree4 - assume hold fraglock6
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*/
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void
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ipfragfree6(IP *ip, Fragment6 *frag)
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{
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Fragment6 *fl, **l;
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if(frag->blist)
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freeblist(frag->blist);
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memset(frag->src, 0, IPaddrlen);
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frag->id = 0;
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frag->blist = nil;
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l = &ip->flisthead6;
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for(fl = *l; fl; fl = fl->next) {
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if(fl == frag) {
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*l = frag->next;
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break;
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}
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l = &fl->next;
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}
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frag->next = ip->fragfree6;
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ip->fragfree6 = frag;
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}
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/*
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* ipfragallo6 - copied from ipfragalloc4
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*/
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Fragment6*
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ipfragallo6(IP *ip)
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{
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Fragment6 *f;
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while(ip->fragfree6 == nil) {
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/* free last entry on fraglist */
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for(f = ip->flisthead6; f->next; f = f->next)
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;
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ipfragfree6(ip, f);
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}
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f = ip->fragfree6;
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ip->fragfree6 = f->next;
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f->next = ip->flisthead6;
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ip->flisthead6 = f;
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f->age = NOW + 30000;
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return f;
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}
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static Block*
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procxtns(IP *ip, Block *bp, int doreasm)
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{
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int offset;
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uchar proto;
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Ip6hdr *h;
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h = (Ip6hdr *)bp->rp;
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offset = unfraglen(bp, &proto, 0);
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if(proto == FH && doreasm != 0) {
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bp = ip6reassemble(ip, offset, bp, h);
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if(bp == nil)
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return nil;
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offset = unfraglen(bp, &proto, 0);
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}
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if(proto == DOH || offset > IP6HDR)
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bp = procopts(bp);
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return bp;
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}
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/*
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* returns length of "Unfragmentable part", i.e., sum of lengths of ipv6 hdr,
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* hop-by-hop & routing headers if present; *nexthdr is set to nexthdr value
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* of the last header in the "Unfragmentable part"; if setfh != 0, nexthdr
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* field of the last header in the "Unfragmentable part" is set to FH.
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*/
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int
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unfraglen(Block *bp, uchar *nexthdr, int setfh)
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{
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uchar *p, *q;
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int ufl, hs;
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p = bp->rp;
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q = p+6; /* proto, = p+sizeof(Ip6hdr.vcf)+sizeof(Ip6hdr.ploadlen) */
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*nexthdr = *q;
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ufl = IP6HDR;
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p += ufl;
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while (*nexthdr == HBH || *nexthdr == RH) {
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*nexthdr = *p;
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hs = ((int)*(p+1) + 1) * 8;
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ufl += hs;
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q = p;
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p += hs;
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}
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if(*nexthdr == FH)
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*q = *p;
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if(setfh)
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*q = FH;
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return ufl;
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}
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Block*
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procopts(Block *bp)
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{
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return bp;
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}
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Block*
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ip6reassemble(IP* ip, int uflen, Block* bp, Ip6hdr* ih)
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{
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int fend, offset, ovlap, len, fragsize, pktposn;
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uint id;
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uchar src[IPaddrlen], dst[IPaddrlen];
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Block *bl, **l, *last, *prev;
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Fraghdr6 *fraghdr;
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Fragment6 *f, *fnext;
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fraghdr = (Fraghdr6 *)(bp->rp + uflen);
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memmove(src, ih->src, IPaddrlen);
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memmove(dst, ih->dst, IPaddrlen);
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id = nhgetl(fraghdr->id);
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offset = nhgets(fraghdr->offsetRM) & ~7;
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/*
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* block lists are too hard, pullupblock into a single block
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*/
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if(bp->next){
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bp = pullupblock(bp, blocklen(bp));
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ih = (Ip6hdr *)bp->rp;
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}
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qlock(&ip->fraglock6);
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/*
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* find a reassembly queue for this fragment
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*/
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for(f = ip->flisthead6; f; f = fnext){
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fnext = f->next;
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if(ipcmp(f->src, src)==0 && ipcmp(f->dst, dst)==0 && f->id == id)
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break;
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if(f->age < NOW){
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ip->stats[ReasmTimeout]++;
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ipfragfree6(ip, f);
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}
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}
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/*
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* if this isn't a fragmented packet, accept it
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* and get rid of any fragments that might go
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* with it.
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*/
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if(nhgets(fraghdr->offsetRM) == 0) { /* 1st frag is also last */
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if(f) {
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ipfragfree6(ip, f);
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ip->stats[ReasmFails]++;
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}
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qunlock(&ip->fraglock6);
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return bp;
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}
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if(bp->base+IPFRAGSZ >= bp->rp){
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bp = padblock(bp, IPFRAGSZ);
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bp->rp += IPFRAGSZ;
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}
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BKFG(bp)->foff = offset;
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BKFG(bp)->flen = nhgets(ih->ploadlen) + IP6HDR - uflen - IP6FHDR;
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/* First fragment allocates a reassembly queue */
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if(f == nil) {
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f = ipfragallo6(ip);
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f->id = id;
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memmove(f->src, src, IPaddrlen);
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memmove(f->dst, dst, IPaddrlen);
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f->blist = bp;
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qunlock(&ip->fraglock6);
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ip->stats[ReasmReqds]++;
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return nil;
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}
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/*
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* find the new fragment's position in the queue
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*/
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prev = nil;
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l = &f->blist;
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bl = f->blist;
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while(bl != nil && BKFG(bp)->foff > BKFG(bl)->foff) {
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prev = bl;
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l = &bl->next;
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bl = bl->next;
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}
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/* Check overlap of a previous fragment - trim away as necessary */
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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 && BKFG(bl)->foff == pktposn; bl = bl->next) {
|
|
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;
|
|
}
|