d2a7d88662
This adds a new route "t"-flag that enables network address translation, replacing the source address (and local port) of a forwarded packet to one of the outgoing interface. The state for a translation is kept in a new Translation structure, which contains two Iphash entries, so it can be inserted into the per protocol 4-tuple hash table, requiering no extra lookups. Translations have a low overhead (~200 bytes on amd64), so we can have many of them. They get reused after 5 minutes of inactivity or when the per protocol limit of 1000 entries is reached (then the one with longest inactivity is reused). The protocol needs to export a "forward" function that is responsible for modifying the forwarded packet, and then handle translations in its input function for iphash hits with Iphash.trans != 0. This patch also fixes a few minor things found during development: - Include the Iphash in the Conv structure, avoiding estra malloc - Fix ttl exceeded check (ttl < 1 -> ttl <= 1) - Router should not reply with ttl exceeded for multicast flows - Extra checks for icmp advice to avoid protocol confusions.
680 lines
13 KiB
C
680 lines
13 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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static char *statnames[] =
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{
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[Forwarding] "Forwarding",
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[DefaultTTL] "DefaultTTL",
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[InReceives] "InReceives",
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[InHdrErrors] "InHdrErrors",
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[InAddrErrors] "InAddrErrors",
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[ForwDatagrams] "ForwDatagrams",
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[InUnknownProtos] "InUnknownProtos",
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[InDiscards] "InDiscards",
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[InDelivers] "InDelivers",
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[OutRequests] "OutRequests",
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[OutDiscards] "OutDiscards",
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[OutNoRoutes] "OutNoRoutes",
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[ReasmTimeout] "ReasmTimeout",
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[ReasmReqds] "ReasmReqds",
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[ReasmOKs] "ReasmOKs",
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[ReasmFails] "ReasmFails",
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[FragOKs] "FragOKs",
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[FragFails] "FragFails",
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[FragCreates] "FragCreates",
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};
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static Block* ip4reassemble(IP*, int, Block*);
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static void ipfragfree4(IP*, Fragment4*);
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static Fragment4* ipfragallo4(IP*);
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static void
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initfrag(IP *ip, int size)
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{
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Fragment4 *fq4, *eq4;
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Fragment6 *fq6, *eq6;
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ip->fragfree4 = (Fragment4*)malloc(sizeof(Fragment4) * size);
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if(ip->fragfree4 == nil)
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panic("initfrag");
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eq4 = &ip->fragfree4[size];
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for(fq4 = ip->fragfree4; fq4 < eq4; fq4++)
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fq4->next = fq4+1;
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ip->fragfree4[size-1].next = nil;
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ip->fragfree6 = (Fragment6*)malloc(sizeof(Fragment6) * size);
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if(ip->fragfree6 == nil)
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panic("initfrag");
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eq6 = &ip->fragfree6[size];
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for(fq6 = ip->fragfree6; fq6 < eq6; fq6++)
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fq6->next = fq6+1;
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ip->fragfree6[size-1].next = nil;
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}
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void
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ip_init(Fs *f)
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{
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IP *ip;
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ip = smalloc(sizeof(IP));
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ip->stats[DefaultTTL] = MAXTTL;
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initfrag(ip, 100);
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f->ip = ip;
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ip_init_6(f);
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}
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void
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iprouting(Fs *f, int on)
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{
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f->ip->iprouting = on;
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if(f->ip->iprouting==0)
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f->ip->stats[Forwarding] = 2;
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else
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f->ip->stats[Forwarding] = 1;
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}
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int
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ipoput4(Fs *f, Block *bp, int gating, int ttl, int tos, Routehint *rh)
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{
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Ipifc *ifc;
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uchar *gate;
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ulong fragoff;
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Block *xp, *nb;
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Ip4hdr *eh, *feh;
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int lid, len, seglen, chunk, hlen, dlen, blklen, offset, medialen;
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Route *r;
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IP *ip;
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int rv = 0;
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ip = f->ip;
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ip->stats[OutRequests]++;
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/* Fill out the ip header */
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eh = (Ip4hdr*)bp->rp;
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assert(BLEN(bp) >= IP4HDR);
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len = blocklen(bp);
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if(len >= IP_MAX){
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ip->stats[OutDiscards]++;
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netlog(f, Logip, "%V -> %V: exceeded ip max size: %d\n", eh->src, eh->dst, len);
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goto free;
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}
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r = v4lookup(f, eh->dst, eh->src, rh);
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if(r == nil || (ifc = r->ifc) == nil){
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ip->stats[OutNoRoutes]++;
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netlog(f, Logip, "%V -> %V: no interface\n", eh->src, eh->dst);
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rv = -1;
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goto free;
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}
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if(r->type & (Rifc|Runi|Rbcast|Rmulti))
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gate = eh->dst;
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else
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gate = r->v4.gate;
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if(!canrlock(ifc)){
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ip->stats[OutDiscards]++;
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goto free;
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}
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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(!gating){
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eh->vihl = IP_VER4|IP_HLEN4;
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eh->tos = tos;
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}
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eh->ttl = ttl;
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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->length, len);
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if(!gating){
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hnputs(eh->id, incref(&ip->id4));
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eh->frag[0] = 0;
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eh->frag[1] = 0;
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}
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eh->cksum[0] = 0;
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eh->cksum[1] = 0;
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hnputs(eh->cksum, ipcsum(&eh->vihl));
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ipifcoput(ifc, bp, V4, gate, rh);
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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(eh->frag[0] & (IP_DF>>8)){
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ip->stats[FragFails]++;
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ip->stats[OutDiscards]++;
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icmpcantfrag(f, bp, medialen);
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netlog(f, Logip, "%V -> %V: can't fragment with DF flag set\n", eh->src, eh->dst);
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goto raise;
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}
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hlen = (eh->vihl & 0xF)<<2;
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seglen = (medialen - hlen) & ~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, "%V -> %V: can't fragment with seglen < 8\n", eh->src, eh->dst);
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goto raise;
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}
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dlen = len - hlen;
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xp = bp;
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if(gating)
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lid = nhgets(eh->id);
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else
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lid = incref(&ip->id4);
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offset = hlen;
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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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if(gating)
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fragoff = nhgets(eh->frag)<<3;
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else
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fragoff = 0;
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dlen += fragoff;
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for(; fragoff < dlen; fragoff += seglen) {
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nb = allocb(hlen+seglen);
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feh = (Ip4hdr*)nb->rp;
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memmove(nb->wp, eh, hlen);
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nb->wp += hlen;
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if((fragoff + seglen) >= dlen) {
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seglen = dlen - fragoff;
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hnputs(feh->frag, fragoff>>3);
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}
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else
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hnputs(feh->frag, (fragoff>>3)|IP_MF);
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hnputs(feh->length, seglen + hlen);
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hnputs(feh->id, lid);
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/* Copy up the data area */
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chunk = seglen;
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while(chunk) {
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if(xp == nil) {
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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 == nil: chunk %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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feh->cksum[0] = 0;
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feh->cksum[1] = 0;
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hnputs(feh->cksum, ipcsum(&feh->vihl));
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ipifcoput(ifc, nb, V4, gate, rh);
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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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ipiput4(Fs *f, Ipifc *ifc, Block *bp)
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{
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int hl, len, hop;
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uchar v6dst[IPaddrlen];
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ushort frag;
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Ip4hdr *h;
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Proto *p;
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IP *ip;
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if((bp->rp[0]&0xF0) != IP_VER4) {
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ipiput6(f, ifc, bp);
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return;
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}
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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 < IP4HDR)
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hl = IP4HDR;
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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 = (Ip4hdr*)bp->rp;
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hl = (h->vihl & 0xF)<<2;
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if(hl < IP4HDR || hl > BLEN(bp)) {
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ip->stats[InHdrErrors]++;
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netlog(f, Logip, "%V -> %V: bad ip header length: %d\n", h->src, h->dst, hl);
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goto drop;
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}
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if((bp->flag & Bipck) == 0 && ipcsum(&h->vihl)) {
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ip->stats[InHdrErrors]++;
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netlog(f, Logip, "%V -> %V: bad ip header checksum\n", h->src, h->dst);
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goto drop;
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}
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len = nhgets(h->length);
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if(len < hl || (bp = trimblock(bp, 0, len)) == nil){
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ip->stats[InHdrErrors]++;
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netlog(f, Logip, "%V -> %V: bogus packet length: %d\n", h->src, h->dst, len);
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if(bp != nil)
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goto drop;
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return;
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}
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h = (Ip4hdr*)bp->rp;
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/* route */
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v4tov6(v6dst, h->dst);
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if(!ipforme(f, v6dst)) {
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Routehint rh;
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Route *r;
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Ipifc *nifc;
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if(!ip->iprouting)
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goto drop;
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/* don't forward to source's network */
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rh.r = nil;
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rh.a = nil;
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r = v4lookup(f, h->dst, h->src, &rh);
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if(r == nil || (nifc = r->ifc) == nil
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|| (nifc == ifc && !ifc->reflect)){
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ip->stats[OutDiscards]++;
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goto drop;
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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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icmpttlexceeded(f, ifc, bp);
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goto drop;
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}
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if(r->type & Rtrans) {
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p = Fsrcvpcolx(f, h->proto);
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if(p == nil || p->forward == nil){
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ip->stats[OutDiscards]++;
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goto drop;
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}
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if(hl > IP4HDR) {
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hl -= IP4HDR;
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len -= hl;
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bp->rp += hl;
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memmove(bp->rp, h, IP4HDR);
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h = (Ip4hdr*)bp->rp;
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h->vihl = IP_VER4|IP_HLEN4;
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hnputs(h->length, len);
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}
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frag = nhgets(h->frag);
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if(frag & (IP_MF|IP_FO)) {
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bp = ip4reassemble(ip, frag, bp);
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if(bp == nil)
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return;
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}
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bp = (*p->forward)(p, bp, r);
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if(bp == nil)
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return;
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h = (Ip4hdr*)bp->rp;
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} else if(nifc->reassemble) {
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/* reassemble as the interface expects it */
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frag = nhgets(h->frag);
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if(frag & (IP_MF|IP_FO)) {
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bp = ip4reassemble(ip, frag, bp);
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if(bp == nil)
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return;
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h = (Ip4hdr*)bp->rp;
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}
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}
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ip->stats[ForwDatagrams]++;
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ipoput4(f, bp, 1, hop - 1, h->tos, &rh);
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return;
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}
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/* If this is not routed strip off the options */
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if(hl > IP4HDR) {
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hl -= IP4HDR;
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len -= hl;
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bp->rp += hl;
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memmove(bp->rp, h, IP4HDR);
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h = (Ip4hdr*)bp->rp;
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h->vihl = IP_VER4|IP_HLEN4;
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hnputs(h->length, len);
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}
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frag = nhgets(h->frag);
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if(frag & (IP_MF|IP_FO)) {
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bp = ip4reassemble(ip, frag, bp);
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if(bp == nil)
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return;
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h = (Ip4hdr*)bp->rp;
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}
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p = Fsrcvpcol(f, h->proto);
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if(p != nil && p->rcv != nil) {
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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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drop:
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freeblist(bp);
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}
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int
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ipstats(Fs *f, char *buf, int len)
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{
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IP *ip;
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char *p, *e;
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int i;
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ip = f->ip;
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p = buf;
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e = p+len;
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for(i = 0; i < Nipstats; i++)
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p = seprint(p, e, "%s: %llud\n", statnames[i], ip->stats[i]);
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return p - buf;
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}
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static Block*
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ip4reassemble(IP *ip, int offset, Block *bp)
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{
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int ovlap, fragsize, len;
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ulong src, dst;
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ushort id;
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Block *bl, **l, *prev;
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Fragment4 *f, *fnext;
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Ipfrag *fp, *fq;
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Ip4hdr *ih;
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/*
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* block lists are too hard, concatblock into a single block
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*/
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bp = concatblock(bp);
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ih = (Ip4hdr*)bp->rp;
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src = nhgetl(ih->src);
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dst = nhgetl(ih->dst);
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id = nhgets(ih->id);
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fragsize = BLEN(bp) - ((ih->vihl&0xF)<<2);
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qlock(&ip->fraglock4);
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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->flisthead4; f != nil; f = fnext){
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fnext = f->next; /* because ipfragfree4 changes the list */
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if(f->id == id && f->src == src && f->dst == dst)
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break;
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if(f->age < NOW){
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ip->stats[ReasmTimeout]++;
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ipfragfree4(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((offset & (IP_MF|IP_FO)) == 0) {
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if(f != nil) {
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ip->stats[ReasmFails]++;
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ipfragfree4(ip, f);
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}
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qunlock(&ip->fraglock4);
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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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fp = (Ipfrag*)bp->base;
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fp->foff = (offset & IP_FO)<<3;
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fp->flen = fragsize;
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/* First fragment allocates a reassembly queue */
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if(f == nil) {
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f = ipfragallo4(ip);
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f->id = id;
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f->src = src;
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f->dst = dst;
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f->blist = bp;
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ip->stats[ReasmReqds]++;
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qunlock(&ip->fraglock4);
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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 && fp->foff > ((Ipfrag*)bl->base)->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 != nil) {
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fq = (Ipfrag*)prev->base;
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ovlap = fq->foff + fq->flen - fp->foff;
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if(ovlap > 0) {
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if(ovlap >= fp->flen) {
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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);
|
|
}
|