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- #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 Ip4hdr Ip4hdr;
- typedef struct IP IP;
- typedef struct Fragment4 Fragment4;
- typedef struct Fragment6 Fragment6;
- typedef struct Ipfrag Ipfrag;
- 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 = 64*1024, /* Maximum Internet packet size */
- };
- #define BLKIPVER(xp) (((Ip4hdr*)((xp)->rp))->vihl&0xF0)
- struct Ip4hdr
- {
- uchar vihl; /* Version and header length */
- uchar tos; /* Type of service */
- uchar length[2]; /* packet length */
- uchar id[2]; /* ip->identification */
- uchar frag[2]; /* Fragment information */
- uchar ttl; /* Time to live */
- uchar proto; /* Protocol */
- uchar cksum[2]; /* Header checksum */
- uchar src[4]; /* IP source */
- uchar dst[4]; /* IP destination */
- };
- /* MIB II counters */
- enum
- {
- Forwarding,
- DefaultTTL,
- InReceives,
- InHdrErrors,
- InAddrErrors,
- ForwDatagrams,
- InUnknownProtos,
- InDiscards,
- InDelivers,
- OutRequests,
- OutDiscards,
- OutNoRoutes,
- ReasmTimeout,
- ReasmReqds,
- ReasmOKs,
- ReasmFails,
- FragOKs,
- FragFails,
- FragCreates,
- Nstats,
- };
- 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 */
- };
- 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",
- };
- #define BLKIP(xp) ((Ip4hdr*)((xp)->rp))
- /*
- * This sleazy macro relies on the media header size being
- * larger than sizeof(Ipfrag). ipreassemble checks this is true
- */
- #define BKFG(xp) ((Ipfrag*)((xp)->base))
- ushort ipcsum(uchar*);
- Block* ip4reassemble(IP*, int, Block*, Ip4hdr*);
- void ipfragfree4(IP*, Fragment4*);
- Fragment4* ipfragallo4(IP*);
- void
- ip_init_6(Fs *f)
- {
- v6params *v6p;
- v6p = smalloc(sizeof(v6params));
-
- v6p->rp.mflag = 0; // default not managed
- v6p->rp.oflag = 0;
- v6p->rp.maxraint = 600000; // millisecs
- v6p->rp.minraint = 200000;
- v6p->rp.linkmtu = 0; // no mtu sent
- v6p->rp.reachtime = 0;
- v6p->rp.rxmitra = 0;
- v6p->rp.ttl = MAXTTL;
- v6p->rp.routerlt = 3*(v6p->rp.maxraint);
- v6p->hp.rxmithost = 1000; // v6 RETRANS_TIMER
- v6p->cdrouter = -1;
- f->v6p = v6p;
- }
- 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));
- 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, int gating, int ttl, int tos, Conv *c)
- {
- Ipifc *ifc;
- uchar *gate;
- ulong fragoff;
- Block *xp, *nb;
- Ip4hdr *eh, *feh;
- int lid, len, seglen, chunk, dlen, blklen, offset, medialen;
- Route *r, *sr;
- IP *ip;
- int rv = 0;
- ip = f->ip;
- /* Fill out the ip header */
- eh = (Ip4hdr*)(bp->rp);
- ip->stats[OutRequests]++;
- /* Number of uchars in data and ip header to write */
- len = blocklen(bp);
- if(gating){
- chunk = nhgets(eh->length);
- if(chunk > len){
- ip->stats[OutDiscards]++;
- netlog(f, Logip, "short gated packet\n");
- goto free;
- }
- if(chunk < len)
- len = chunk;
- }
- if(len >= IP_MAX){
- ip->stats[OutDiscards]++;
- netlog(f, Logip, "exceeded ip max size %V\n", eh->dst);
- goto free;
- }
- r = v4lookup(f, eh->dst, c);
- if(r == nil){
- ip->stats[OutNoRoutes]++;
- netlog(f, Logip, "no interface %V\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 = v4lookup(f, eh->src, nil);
- if(sr != nil && (sr->type & Runi))
- ifc = sr->ifc;
- }
- else
- gate = r->v4.gate;
- if(!gating)
- eh->vihl = IP_VER4|IP_HLEN4;
- eh->ttl = ttl;
- if(!gating)
- eh->tos = tos;
- 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) {
- if(!gating)
- hnputs(eh->id, incref(&ip->id4));
- hnputs(eh->length, len);
- if(!gating){
- eh->frag[0] = 0;
- eh->frag[1] = 0;
- }
- eh->cksum[0] = 0;
- eh->cksum[1] = 0;
- hnputs(eh->cksum, ipcsum(&eh->vihl));
- ifc->m->bwrite(ifc, bp, V4, gate);
- runlock(ifc);
- poperror();
- return 0;
- }
- if((eh->frag[0] & (IP_DF>>8)) && !gating) print("%V: DF set\n", eh->dst);
- if(eh->frag[0] & (IP_DF>>8)){
- ip->stats[FragFails]++;
- ip->stats[OutDiscards]++;
- icmpcantfrag(f, bp, medialen);
- netlog(f, Logip, "%V: eh->frag[0] & (IP_DF>>8)\n", eh->dst);
- goto raise;
- }
- seglen = (medialen - IP4HDR) & ~7;
- if(seglen < 8){
- ip->stats[FragFails]++;
- ip->stats[OutDiscards]++;
- netlog(f, Logip, "%V seglen < 8\n", eh->dst);
- goto raise;
- }
- dlen = len - IP4HDR;
- xp = bp;
- if(gating)
- lid = nhgets(eh->id);
- else
- lid = incref(&ip->id4);
- offset = IP4HDR;
- while(xp != nil && 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(IP4HDR+seglen);
- feh = (Ip4hdr*)(nb->rp);
- memmove(nb->wp, eh, IP4HDR);
- nb->wp += IP4HDR;
- if((fragoff + seglen) >= dlen) {
- seglen = dlen - fragoff;
- hnputs(feh->frag, fragoff>>3);
- }
- else
- hnputs(feh->frag, (fragoff>>3)|IP_MF);
- hnputs(feh->length, seglen + IP4HDR);
- hnputs(feh->id, lid);
- /* Copy up the data area */
- chunk = seglen;
- while(chunk) {
- if(!xp) {
- ip->stats[OutDiscards]++;
- ip->stats[FragFails]++;
- freeblist(nb);
- netlog(f, Logip, "!xp: 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));
- ifc->m->bwrite(ifc, nb, V4, gate);
- 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;
- int hop, tos, proto, olen;
- Ip4hdr *h;
- Proto *p;
- ushort frag;
- int notforme;
- uchar *dp, v6dst[IPaddrlen];
- IP *ip;
- Route *r;
- if(BLKIPVER(bp) != 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);
- /* dump anything that whose header doesn't checksum */
- if((bp->flag & Bipck) == 0 && ipcsum(&h->vihl)) {
- ip->stats[InHdrErrors]++;
- netlog(f, Logip, "ip: checksum error %V\n", h->src);
- freeblist(bp);
- return;
- }
- v4tov6(v6dst, h->dst);
- notforme = ipforme(f, v6dst) == 0;
- /* Check header length and version */
- if((h->vihl&0x0F) != IP_HLEN4) {
- hl = (h->vihl&0xF)<<2;
- if(hl < (IP_HLEN4<<2)) {
- ip->stats[InHdrErrors]++;
- netlog(f, Logip, "ip: %V bad hivl %ux\n", h->src, h->vihl);
- freeblist(bp);
- return;
- }
- /* If this is not routed strip off the options */
- if(notforme == 0) {
- olen = nhgets(h->length);
- dp = bp->rp + (hl - (IP_HLEN4<<2));
- memmove(dp, h, IP_HLEN4<<2);
- bp->rp = dp;
- h = (Ip4hdr*)(bp->rp);
- h->vihl = (IP_VER4|IP_HLEN4);
- hnputs(h->length, olen-hl+(IP_HLEN4<<2));
- }
- }
- /* route */
- if(notforme) {
- Conv conv;
- if(!ip->iprouting){
- freeb(bp);
- return;
- }
- /* don't forward to source's network */
- conv.r = nil;
- r = v4lookup(f, h->dst, &conv);
- if(r == nil || r->ifc == ifc){
- ip->stats[OutDiscards]++;
- freeblist(bp);
- return;
- }
- /* don't forward if packet has timed out */
- hop = h->ttl;
- if(hop < 1) {
- ip->stats[InHdrErrors]++;
- icmpttlexceeded(f, ifc->lifc->local, bp);
- freeblist(bp);
- return;
- }
- /* reassemble if the interface expects it */
- if(r->ifc == nil) panic("nil route rfc");
- if(r->ifc->reassemble){
- frag = nhgets(h->frag);
- if(frag) {
- h->tos = 0;
- if(frag & IP_MF)
- h->tos = 1;
- bp = ip4reassemble(ip, frag, bp, h);
- if(bp == nil)
- return;
- h = (Ip4hdr*)(bp->rp);
- }
- }
- ip->stats[ForwDatagrams]++;
- tos = h->tos;
- hop = h->ttl;
- ipoput4(f, bp, 1, hop - 1, tos, &conv);
- return;
- }
- frag = nhgets(h->frag);
- if(frag) {
- h->tos = 0;
- if(frag & IP_MF)
- h->tos = 1;
- bp = ip4reassemble(ip, frag, bp, h);
- if(bp == nil)
- return;
- h = (Ip4hdr*)(bp->rp);
- }
- /* don't let any frag info go up the stack */
- h->frag[0] = 0;
- h->frag[1] = 0;
- 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);
- }
- int
- ipstats(Fs *f, char *buf, int len)
- {
- IP *ip;
- char *p, *e;
- int i;
- ip = f->ip;
- ip->stats[DefaultTTL] = MAXTTL;
- p = buf;
- e = p+len;
- for(i = 0; i < Nstats; i++)
- p = seprint(p, e, "%s: %lud\n", statnames[i], ip->stats[i]);
- return p - buf;
- }
- Block*
- ip4reassemble(IP *ip, int offset, Block *bp, Ip4hdr *ih)
- {
- int fend;
- ushort id;
- Fragment4 *f, *fnext;
- ulong src, dst;
- Block *bl, **l, *last, *prev;
- int ovlap, len, fragsize, pktposn;
- src = nhgetl(ih->src);
- dst = nhgetl(ih->dst);
- id = nhgets(ih->id);
- /*
- * block lists are too hard, pullupblock into a single block
- */
- if(bp->next){
- bp = pullupblock(bp, blocklen(bp));
- ih = (Ip4hdr*)(bp->rp);
- }
- qlock(&ip->fraglock4);
- /*
- * find a reassembly queue for this fragment
- */
- for(f = ip->flisthead4; f; f = fnext){
- fnext = f->next; /* because ipfragfree4 changes the list */
- if(f->src == src && f->dst == dst && f->id == id)
- 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(!ih->tos && (offset & ~(IP_MF|IP_DF)) == 0) {
- if(f != nil) {
- ipfragfree4(ip, f);
- ip->stats[ReasmFails]++;
- }
- qunlock(&ip->fraglock4);
- return bp;
- }
- if(bp->base+sizeof(Ipfrag) >= bp->rp){
- bp = padblock(bp, sizeof(Ipfrag));
- bp->rp += sizeof(Ipfrag);
- }
- BKFG(bp)->foff = offset<<3;
- BKFG(bp)->flen = nhgets(ih->length)-IP4HDR;
- /* First fragment allocates a reassembly queue */
- if(f == nil) {
- f = ipfragallo4(ip);
- f->id = id;
- f->src = src;
- f->dst = dst;
- f->blist = bp;
- qunlock(&ip->fraglock4);
- 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->fraglock4);
- 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, IP4HDR);
- (*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
- * without IP_MF set, we're done.
- */
- pktposn = 0;
- for(bl = f->blist; bl; bl = bl->next) {
- if(BKFG(bl)->foff != pktposn)
- break;
- if((BLKIP(bl)->frag[0]&(IP_MF>>8)) == 0) {
- bl = f->blist;
- len = nhgets(BLKIP(bl)->length);
- bl->wp = bl->rp + len;
- /* 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 += IP4HDR;
- bl->wp = bl->rp + fragsize;
- }
- bl = f->blist;
- f->blist = nil;
- ipfragfree4(ip, f);
- ih = BLKIP(bl);
- hnputs(ih->length, len);
- qunlock(&ip->fraglock4);
- ip->stats[ReasmOKs]++;
- return bl;
- }
- pktposn += BKFG(bl)->flen;
- }
- qunlock(&ip->fraglock4);
- return nil;
- }
- /*
- * ipfragfree4 - Free a list of fragments - assume hold fraglock4
- */
- void
- ipfragfree4(IP *ip, Fragment4 *frag)
- {
- Fragment4 *fl, **l;
- if(frag->blist)
- freeblist(frag->blist);
- frag->src = 0;
- frag->id = 0;
- frag->blist = nil;
- l = &ip->flisthead4;
- for(fl = *l; fl; 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
- */
- Fragment4 *
- ipfragallo4(IP *ip)
- {
- Fragment4 *f;
- while(ip->fragfree4 == nil) {
- /* free last entry on fraglist */
- for(f = ip->flisthead4; f->next; 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);
- }
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