ref: 37e65b331bdf98f409be1bd2fbb55aec158c7877
dir: /sys/src/9/ip/icmp.c/
#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 Icmp { uchar vihl; /* Version and header length */ uchar tos; /* Type of service */ uchar length[2]; /* packet length */ uchar id[2]; /* Identification */ uchar frag[2]; /* Fragment information */ uchar ttl; /* Time to live */ uchar proto; /* Protocol */ uchar ipcksum[2]; /* Header checksum */ uchar src[4]; /* Ip source */ uchar dst[4]; /* Ip destination */ uchar type; uchar code; uchar cksum[2]; uchar icmpid[2]; uchar seq[2]; uchar data[1]; } Icmp; enum { /* Packet Types */ EchoReply = 0, Unreachable = 3, SrcQuench = 4, Redirect = 5, EchoRequest = 8, TimeExceed = 11, InParmProblem = 12, Timestamp = 13, TimestampReply = 14, InfoRequest = 15, InfoReply = 16, AddrMaskRequest = 17, AddrMaskReply = 18, Maxtype = 18, }; char *icmpnames[Maxtype+1] = { [EchoReply] "EchoReply", [Unreachable] "Unreachable", [SrcQuench] "SrcQuench", [Redirect] "Redirect", [EchoRequest] "EchoRequest", [TimeExceed] "TimeExceed", [InParmProblem] "InParmProblem", [Timestamp] "Timestamp", [TimestampReply] "TimestampReply", [InfoRequest] "InfoRequest", [InfoReply] "InfoReply", [AddrMaskRequest] "AddrMaskRequest", [AddrMaskReply ] "AddrMaskReply ", }; enum { IP_ICMPPROTO = 1, ICMP_IPSIZE = 20, ICMP_HDRSIZE = 8, MinAdvise = IP4HDR+4, /* minimum needed for us to advise another protocol */ }; enum { InMsgs, InErrors, OutMsgs, CsumErrs, LenErrs, HlenErrs, Nstats, }; static char *statnames[Nstats] = { [InMsgs] "InMsgs", [InErrors] "InErrors", [OutMsgs] "OutMsgs", [CsumErrs] "CsumErrs", [LenErrs] "LenErrs", [HlenErrs] "HlenErrs", }; typedef struct Icmppriv Icmppriv; struct Icmppriv { ulong stats[Nstats]; /* message counts */ ulong in[Maxtype+1]; ulong out[Maxtype+1]; Ipht ht; }; static void icmpkick(void *x, Block*); static void icmpcreate(Conv *c) { c->rq = qopen(64*1024, Qmsg, 0, c); c->wq = qbypass(icmpkick, c); } char* icmpconnect(Conv *c, char **argv, int argc) { char *e; e = Fsstdconnect(c, argv, argc); if(e != nil) return e; Fsconnected(c, e); return nil; } int icmpstate(Conv *c, char *state, int n) { USED(c); return snprint(state, n, "%s qin %d qout %d\n", "Datagram", c->rq ? qlen(c->rq) : 0, c->wq ? qlen(c->wq) : 0 ); } char* icmpannounce(Conv *c, char **argv, int argc) { char *e; e = Fsstdannounce(c, argv, argc); if(e != nil) return e; Fsconnected(c, nil); return nil; } void icmpclose(Conv *c) { qclose(c->rq); qclose(c->wq); ipmove(c->laddr, IPnoaddr); ipmove(c->raddr, IPnoaddr); c->lport = 0; } static void icmpkick(void *x, Block *bp) { Conv *c = x; Icmp *p; Icmppriv *ipriv; if(bp == nil) return; if(BLEN(bp) < ICMP_IPSIZE + ICMP_HDRSIZE){ freeblist(bp); return; } p = (Icmp *)(bp->rp); p->vihl = IP_VER4; ipriv = c->p->priv; if(p->type <= Maxtype) ipriv->out[p->type]++; v6tov4(p->dst, c->raddr); v6tov4(p->src, c->laddr); p->proto = IP_ICMPPROTO; hnputs(p->icmpid, c->lport); memset(p->cksum, 0, sizeof(p->cksum)); hnputs(p->cksum, ptclcsum(bp, ICMP_IPSIZE, blocklen(bp) - ICMP_IPSIZE)); ipriv->stats[OutMsgs]++; ipoput4(c->p->f, bp, nil, c->ttl, c->tos, nil); } static int ip4reply(Fs *f, uchar ip4[4]) { uchar addr[IPaddrlen]; int i; if(isv4mcast(ip4)) return 0; v4tov6(addr, ip4); i = ipforme(f, addr); return i == 0 || i == Runi; } static int ip4me(Fs *f, uchar ip4[4]) { uchar addr[IPaddrlen]; if(isv4mcast(ip4)) return 0; v4tov6(addr, ip4); return ipforme(f, addr) == Runi; } /* * Send a ICMP packet back of type/code/arg in response to packet bp * which was received on ifc. The route hint rh is valid for the * reverse route. */ static void icmpsend(Fs *f, Ipifc *ifc, Block *bp, int type, int code, int arg, Routehint *rh) { Proto *icmp; uchar ia[IPv4addrlen]; Block *nbp; Icmp *np, *p; int sz, osz; osz = BLEN(bp); if(osz < IP4HDR) return; p = (Icmp *)bp->rp; if(!ip4reply(f, p->dst) || !ip4reply(f, p->src) || !ipv4local(ifc, ia, 0, p->src)) return; netlog(f, Logicmp, "icmpsend %s (%d) %d ia %V -> src %V dst %V\n", icmpnames[type], type, code, ia, p->src, p->dst); sz = MIN(ICMP_IPSIZE + ICMP_HDRSIZE + osz, v4MINTU); nbp = allocb(sz); nbp->wp += sz; memset(nbp->rp, 0, sz); np = (Icmp *)nbp->rp; np->vihl = IP_VER4; memmove(np->src, ia, sizeof(np->src)); memmove(np->dst, p->src, sizeof(np->dst)); memmove(np->data, bp->rp, sz - ICMP_IPSIZE - ICMP_HDRSIZE); np->type = type; np->code = code; np->proto = IP_ICMPPROTO; hnputs(np->icmpid, 0); hnputs(np->seq, arg); memset(np->cksum, 0, sizeof(np->cksum)); hnputs(np->cksum, ptclcsum(nbp, ICMP_IPSIZE, blocklen(nbp) - ICMP_IPSIZE)); icmp = f->t2p[IP_ICMPPROTO]; ((Icmppriv*)icmp->priv)->out[type]++; if(rh != nil && rh->r != nil && (rh->r->type & Runi) != 0){ np = (Icmp *)nbp->rp; np->vihl = IP_VER4|IP_HLEN4; np->tos = DFLTTOS; np->ttl = MAXTTL; (*icmp->rcv)(icmp, ifc, nbp); return; } ipoput4(f, nbp, nil, MAXTTL, DFLTTOS, rh); } void icmpnohost(Fs *f, Ipifc *ifc, Block *bp, Routehint *rh) { icmpsend(f, ifc, bp, Unreachable, 1, 0, rh); } void icmpnoconv(Fs *f, Ipifc *ifc, Block *bp) { icmpsend(f, ifc, bp, Unreachable, 3, 0, nil); } void icmpcantfrag(Fs *f, Ipifc *ifc, Block *bp, int mtu) { icmpsend(f, ifc, bp, Unreachable, 4, mtu, nil); } void icmpttlexceeded(Fs *f, Ipifc *ifc, Block *bp) { icmpsend(f, ifc, bp, TimeExceed, 0, 0, nil); } static void goticmpkt(Proto *icmp, Block *bp, Ipifc *ifc) { uchar dst[IPaddrlen], src[IPaddrlen]; ushort recid; Conv **c, *s; Iphash *iph; Icmp *p; p = (Icmp *)bp->rp; v4tov6(dst, p->dst); v4tov6(src, p->src); recid = nhgets(p->icmpid); qlock(icmp); iph = iphtlook(&((Icmppriv*)icmp->priv)->ht, src, recid, dst, recid); if(iph != nil){ Translation *q; int hop = p->ttl; if(hop <= 1 || (q = transbackward(icmp, iph)) == nil) goto raise; memmove(p->dst, q->forward.raddr+IPv4off, IPv4addrlen); hnputs_csum(p->icmpid, q->forward.rport, p->cksum); /* only use route-hint when from original desination */ if(memcmp(p->src, q->forward.laddr+IPv4off, IPv4addrlen) != 0) q = nil; qunlock(icmp); ipoput4(icmp->f, bp, ifc, hop - 1, p->tos, q); return; } for(c = icmp->conv; (s = *c) != nil; c++){ if(s->lport == recid) if(ipcmp(s->laddr, dst) == 0 || ipcmp(s->raddr, src) == 0) qpass(s->rq, copyblock(bp, blocklen(bp))); } raise: qunlock(icmp); freeblist(bp); } static Block * mkechoreply(Block *bp, Fs *f) { Icmp *q; uchar ip[4]; q = (Icmp *)bp->rp; if(!ip4me(f, q->dst) || !ip4reply(f, q->src)) return nil; q->vihl = IP_VER4; memmove(ip, q->src, sizeof(q->dst)); memmove(q->src, q->dst, sizeof(q->src)); memmove(q->dst, ip, sizeof(q->dst)); q->type = EchoReply; memset(q->cksum, 0, sizeof(q->cksum)); hnputs(q->cksum, ptclcsum(bp, ICMP_IPSIZE, blocklen(bp) - ICMP_IPSIZE)); return bp; } static char *unreachcode[] = { [0] "net unreachable", [1] "host unreachable", [2] "protocol unreachable", [3] "port unreachable", [4] "fragmentation needed and DF set", [5] "source route failed", [6] "destination network unknown", [7] "destination host unknown", [8] "source host isolated", [9] "network administratively prohibited", [10] "host administratively prohibited", [11] "network unreachable for tos", [12] "host unreachable for tos", [13] "communication administratively prohibited", [14] "host precedence violation", [15] "precedence cutoff in effect", }; static void icmpiput(Proto *icmp, Ipifc *ifc, Block *bp) { int n; Icmp *p; Block *r; Proto *pr; char *msg; char m2[128]; Icmppriv *ipriv; ipriv = icmp->priv; ipriv->stats[InMsgs]++; bp = concatblock(bp); n = BLEN(bp); if(n < ICMP_IPSIZE+ICMP_HDRSIZE){ ipriv->stats[InErrors]++; ipriv->stats[HlenErrs]++; netlog(icmp->f, Logicmp, "icmp hlen %d\n", n); goto raise; } if(ptclcsum(bp, ICMP_IPSIZE, n - ICMP_IPSIZE)){ ipriv->stats[InErrors]++; ipriv->stats[CsumErrs]++; netlog(icmp->f, Logicmp, "icmp checksum error\n"); goto raise; } p = (Icmp *)bp->rp; netlog(icmp->f, Logicmp, "icmpiput %s (%d) %d\n", (p->type < nelem(icmpnames)? icmpnames[p->type]: ""), p->type, p->code); if(p->type <= Maxtype) ipriv->in[p->type]++; switch(p->type) { case EchoRequest: r = mkechoreply(bp, icmp->f); if(r == nil) goto raise; ipriv->out[EchoReply]++; ipoput4(icmp->f, r, nil, MAXTTL, DFLTTOS, nil); break; case TimeExceed: if(p->code == 0){ snprint(msg = m2, sizeof m2, "ttl exceeded at %V", p->src); goto Advise; } goticmpkt(icmp, bp, ifc); break; case Unreachable: if(p->code >= nelem(unreachcode)) { snprint(m2, sizeof m2, "unreachable %V -> %V code %d", p->src, p->dst, p->code); msg = m2; } else msg = unreachcode[p->code]; Advise: bp->rp += ICMP_IPSIZE+ICMP_HDRSIZE; if(BLEN(bp) < MinAdvise){ ipriv->stats[LenErrs]++; goto raise; } p = (Icmp *)bp->rp; if(p->vihl == (IP_VER4|IP_HLEN4) /* advise() does not expect options */ && (nhgets(p->frag) & IP_FO) == 0 /* first fragment */ && ipcsum(&p->vihl) == 0){ pr = Fsrcvpcolx(icmp->f, p->proto); if(pr != nil && pr->advise != nil) { netlog(icmp->f, Logicmp, "advising %s!%V -> %V: %s\n", pr->name, p->src, p->dst, msg); (*pr->advise)(pr, bp, ifc, msg); return; } } bp->rp -= ICMP_IPSIZE+ICMP_HDRSIZE; /* wet floor */ default: goticmpkt(icmp, bp, ifc); break; } return; raise: freeblist(bp); } /* * called from protocol advice handlers when the advice * is actually for someone we source translate (ip4). * the caller has fixed up the ip address and ports * in the inner header, so we just restore the outer * ip/icmp headers, recalculating icmp checksum * and send the advice to ip4. */ void icmpproxyadvice(Fs *f, Ipifc *ifc, Block *bp, uchar *ip4) { Icmp *p; int hop; /* inner header */ p = (Icmp *) bp->rp; if(p->vihl != (IP_VER4|IP_HLEN4)) goto drop; if(ipcsum(&p->vihl) != 0) goto drop; /* outer header */ bp->rp -= ICMP_IPSIZE+ICMP_HDRSIZE; p = (Icmp *) bp->rp; if(p->vihl != (IP_VER4|(ICMP_IPSIZE>>2))) goto drop; hop = p->ttl; if(hop <= 1) goto drop; netlog(f, Logicmp|Logtrans, "proxying icmp advice from %V to %V->%V\n", p->src, p->dst, ip4); memmove(p->dst, ip4, IPv4addrlen); /* recalculate ICMP checksum */ memset(p->cksum, 0, sizeof(p->cksum)); hnputs(p->cksum, ptclcsum(bp, ICMP_IPSIZE, blocklen(bp) - ICMP_IPSIZE)); ipoput4(f, bp, ifc, hop - 1, p->tos, nil); return; drop: freeblist(bp); } static void icmpadvise(Proto *icmp, Block *bp, Ipifc *ifc, char *msg) { uchar dst[IPaddrlen], src[IPaddrlen]; ushort recid; Conv **c, *s; Icmp *p; Iphash *iph; p = (Icmp *) bp->rp; v4tov6(dst, p->dst); v4tov6(src, p->src); recid = nhgets(p->icmpid); qlock(icmp); iph = iphtlook(&((Icmppriv*)icmp->priv)->ht, dst, recid, src, recid); if(iph != nil){ Translation *q; if((q = transbackward(icmp, iph)) == nil) goto raise; hnputs_csum(p->src+0, nhgets(q->forward.raddr+IPv4off+0), p->ipcksum); hnputs_csum(p->src+2, nhgets(q->forward.raddr+IPv4off+2), p->ipcksum); hnputs_csum(p->icmpid, q->forward.rport, p->cksum); qunlock(icmp); icmpproxyadvice(icmp->f, ifc, bp, p->src); return; } for(c = icmp->conv; (s = *c) != nil; c++){ if(s->lport == recid) if(ipcmp(s->laddr, src) == 0) if(ipcmp(s->raddr, dst) == 0){ if(s->ignoreadvice) break; qhangup(s->rq, msg); qhangup(s->wq, msg); break; } } raise: qunlock(icmp); freeblist(bp); } static Block* icmpforward(Proto *icmp, Block *bp, Route *r) { uchar da[IPaddrlen], sa[IPaddrlen]; ushort id; Icmp *p; Translation *q; p = (Icmp*)(bp->rp); switch(p->type){ case EchoRequest: case Timestamp: case InfoRequest: case AddrMaskRequest: break; default: /* no icmpid, can't translate back */ freeblist(bp); return nil; } v4tov6(sa, p->src); v4tov6(da, p->dst); id = nhgets(p->icmpid); qlock(icmp); q = transforward(icmp, &((Icmppriv*)icmp->priv)->ht, sa, id, da, id, r); if(q == nil){ qunlock(icmp); freeblist(bp); return nil; } memmove(p->src, q->backward.laddr+IPv4off, IPv4addrlen); hnputs_csum(p->icmpid, q->backward.lport, p->cksum); qunlock(icmp); return bp; } static int icmpstats(Proto *icmp, char *buf, int len) { Icmppriv *priv; char *p, *e; int i; priv = icmp->priv; p = buf; e = p+len; for(i = 0; i < Nstats; i++) p = seprint(p, e, "%s: %lud\n", statnames[i], priv->stats[i]); for(i = 0; i <= Maxtype; i++){ if(icmpnames[i] != nil) p = seprint(p, e, "%s: %lud %lud\n", icmpnames[i], priv->in[i], priv->out[i]); else p = seprint(p, e, "%d: %lud %lud\n", i, priv->in[i], priv->out[i]); } return p - buf; } void icmpinit(Fs *fs) { Proto *icmp; icmp = smalloc(sizeof(Proto)); icmp->priv = smalloc(sizeof(Icmppriv)); icmp->name = "icmp"; icmp->connect = icmpconnect; icmp->announce = icmpannounce; icmp->state = icmpstate; icmp->create = icmpcreate; icmp->close = icmpclose; icmp->rcv = icmpiput; icmp->stats = icmpstats; icmp->ctl = nil; icmp->advise = icmpadvise; icmp->forward = icmpforward; icmp->gc = nil; icmp->ipproto = IP_ICMPPROTO; icmp->nc = 128; icmp->ptclsize = 0; Fsproto(fs, icmp); }