ref: 57d690c482c7e5f57608befe7cb04797b1bff153
dir: /sys/src/9/ip/arp.c/
#include "u.h" #include "../port/lib.h" #include "mem.h" #include "dat.h" #include "fns.h" #include "../port/error.h" #include "ip.h" #include "ipv6.h" /* * address resolution tables */ enum { NHASH = (1<<6), NCACHE = 256, AOK = 1, AWAIT = 2, }; char *arpstate[] = { "UNUSED", "OK", "WAIT", }; /* * one per Fs */ struct Arp { QLock; Fs *f; Arpent *hash[NHASH]; Arpent cache[NCACHE]; Arpent *rxmt; Proc *rxmitp; /* neib sol re-transmit proc */ Rendez rxmtq; Block *dropf, *dropl; }; char *Ebadarp = "bad arp"; #define haship(s) ((s)[IPaddrlen-1]%NHASH) int ReTransTimer = RETRANS_TIMER; static void rxmitproc(void *v); void arpinit(Fs *f) { f->arp = smalloc(sizeof(Arp)); f->arp->f = f; f->arp->rxmt = nil; f->arp->dropf = f->arp->dropl = nil; kproc("rxmitproc", rxmitproc, f->arp); } static void freeblistchain(Block *bp) { Block *next; while(bp != nil){ next = bp->list; freeblist(bp); bp = next; } } /* take out of re-transmit chain */ static Arpent** rxmtunchain(Arp *arp, Arpent *a) { Arpent **l; for(l = &arp->rxmt; *l != nil; l = &((*l)->nextrxt)){ if(*l == a){ *l = a->nextrxt; break; } } a->nextrxt = nil; return l; } static void cleanarpent(Arp *arp, Arpent *a) { Arpent **l; Block *bp; /* take out of current chain */ for(l = &arp->hash[haship(a->ip)]; *l != nil; l = &((*l)->hash)){ if(*l == a){ *l = a->hash; break; } } a->hash = nil; /* dump waiting packets */ bp = a->hold; a->hold = nil; if(isv4(a->ip)) freeblistchain(bp); else { rxmtunchain(arp, a); /* queue icmp unreachable for rxmitproc later on, w/o arp lock */ if(bp != nil){ if(arp->dropf == nil) arp->dropf = bp; else arp->dropl->list = bp; arp->dropl = a->last; if(bp == arp->dropf) wakeup(&arp->rxmtq); } } a->last = nil; a->ifc = nil; a->ifcid = 0; a->state = 0; a->rxtsrem = 0; a->utime = 0; a->ctime = 0; memset(a->ip, 0, sizeof(a->ip)); memset(a->mac, 0, sizeof(a->mac)); } /* * create a new arp entry for an ip address on ifc. */ static Arpent* newarpent(Arp *arp, uchar *ip, Ipifc *ifc) { Arpent *a, *e, *f, **l; ulong t; /* find oldest entry */ e = &arp->cache[NCACHE]; a = arp->cache; t = a->utime; for(f = a; f < e; f++){ if(f->utime < t){ t = f->utime; a = f; } } cleanarpent(arp, a); ipmove(a->ip, ip); a->ifc = ifc; a->ifcid = ifc->ifcid; /* insert into new chain */ l = &arp->hash[haship(ip)]; a->hash = *l; *l = a; return a; } /* * fill in the media address if we have it. Otherwise return an * Arpent that represents the state of the address resolution FSM * for ip. Add the packet to be sent onto the list of packets * waiting for ip->mac to be resolved. */ Arpent* arpget(Arp *arp, Block *bp, int version, Ipifc *ifc, uchar *ip, uchar *mac) { int hash; Arpent *a; uchar v6ip[IPaddrlen]; if(version == V4){ v4tov6(v6ip, ip); ip = v6ip; } qlock(arp); hash = haship(ip); for(a = arp->hash[hash]; a != nil; a = a->hash){ if(a->ifc == ifc && a->ifcid == ifc->ifcid && ipcmp(ip, a->ip) == 0) break; } if(a == nil){ a = newarpent(arp, ip, ifc); a->state = AWAIT; } a->utime = NOW; if(a->state == AWAIT){ if(bp != nil){ bp->list = nil; if(a->hold == nil) a->hold = bp; else a->last->list = bp; a->last = bp; } return a; /* return with arp qlocked */ } memmove(mac, a->mac, ifc->m->maclen); /* remove old entries */ if(NOW - a->ctime > 15*60*1000) cleanarpent(arp, a); qunlock(arp); return nil; } /* * called with arp locked */ void arprelease(Arp *arp, Arpent*) { qunlock(arp); } /* * Copy out the mac address from the Arpent. Return the * block waiting to get sent to this mac address. * * called with arp locked */ Block* arpresolve(Arp *arp, Arpent *a, Medium *type, uchar *mac) { Block *bp; memmove(a->mac, mac, type->maclen); if(a->state == AWAIT && !isv4(a->ip)){ rxmtunchain(arp, a); a->rxtsrem = 0; } a->state = AOK; a->ctime = a->utime = NOW; bp = a->hold; a->hold = a->last = nil; qunlock(arp); return bp; } int arpenter(Fs *fs, int version, uchar *ip, uchar *mac, int n, uchar *ia, Ipifc *ifc, int refresh) { uchar v6ip[IPaddrlen]; Block *bp, *next; Arpent *a; Route *r; Arp *arp; if(ifc->m == nil || ifc->m->maclen != n || ifc->m->maclen == 0) return -1; switch(version){ case V4: r = v4lookup(fs, ip, ia, nil); v4tov6(v6ip, ip); ip = v6ip; break; case V6: r = v6lookup(fs, ip, ia, nil); break; default: panic("arpenter: version %d", version); return -1; /* to supress warnings */ } if(r == nil || r->ifc != ifc || (r->type & (Rbcast|Rmulti)) != 0) return -1; arp = fs->arp; qlock(arp); for(a = arp->hash[haship(ip)]; a != nil; a = a->hash){ if(a->ifc != ifc || a->ifcid != ifc->ifcid) continue; if(ipcmp(a->ip, ip) == 0){ if(version == V4) ip += IPv4off; bp = arpresolve(arp, a, ifc->m, mac); /* unlocks arp */ for(; bp != nil; bp = next){ next = bp->list; bp->list = nil; if(waserror()){ freeblistchain(next); break; } ipifcoput(ifc, bp, version, ip); poperror(); } return 1; } } if(refresh == 0){ a = newarpent(arp, ip, ifc); a->state = AOK; a->ctime = a->utime = NOW; memmove(a->mac, mac, n); } qunlock(arp); return refresh == 0; } int arpwrite(Fs *fs, char *s, int len) { int n; Arp *arp; Arpent *a, *x; Medium *m; Ipifc *ifc; char *f[5], buf[256]; uchar ip[IPaddrlen], ia[IPaddrlen], mac[MAClen]; arp = fs->arp; if(len == 0) error(Ebadarp); if(len >= sizeof(buf)) len = sizeof(buf)-1; strncpy(buf, s, len); buf[len] = 0; if(len > 0 && buf[len-1] == '\n') buf[len-1] = 0; n = getfields(buf, f, nelem(f), 1, " "); if(strcmp(f[0], "flush") == 0){ qlock(arp); for(a = arp->cache; a < &arp->cache[NCACHE]; a++){ memset(a->ip, 0, sizeof(a->ip)); memset(a->mac, 0, sizeof(a->mac)); a->hash = nil; a->nextrxt = nil; a->ifc = nil; a->ifcid = 0; a->state = 0; a->rxtsrem = 0; a->ctime = 0; a->utime = 0; freeblistchain(a->hold); a->hold = a->last = nil; } memset(arp->hash, 0, sizeof(arp->hash)); freeblistchain(arp->dropf); arp->dropf = arp->dropl = nil; arp->rxmt = nil; qunlock(arp); } else if(strcmp(f[0], "add") == 0){ switch(n){ default: error(Ebadarg); case 3: if(parseip(ip, f[1]) == -1) error(Ebadip); if((n = parsemac(mac, f[2], sizeof(mac))) <= 0) error(Ebadarp); findlocalip(fs, ia, ip); break; case 4: m = ipfindmedium(f[1]); if(m == nil || m->maclen == 0) error(Ebadarp); if(parseip(ip, f[2]) == -1) error(Ebadip); if((n = parsemac(mac, f[3], sizeof(mac))) != m->maclen) error(Ebadarp); findlocalip(fs, ia, ip); break; case 5: m = ipfindmedium(f[1]); if(m == nil || m->maclen == 0) error(Ebadarp); if(parseip(ip, f[2]) == -1) error(Ebadip); if((n = parsemac(mac, f[3], sizeof(mac))) != m->maclen) error(Ebadarp); if(parseip(ia, f[4]) == -1) error(Ebadip); break; } if((ifc = findipifc(fs, ia, ia, Runi)) == nil) error("no interface"); rlock(ifc); if(!ipv6local(ifc, ia, 0, ip) || arpenter(fs, V6, ip, mac, n, ia, ifc, 0) < 0){ runlock(ifc); error("destination unreachable"); } runlock(ifc); } else if(strcmp(f[0], "del") == 0){ if (n != 2) error(Ebadarg); if (parseip(ip, f[1]) == -1) error(Ebadip); qlock(arp); for(a = arp->hash[haship(ip)]; a != nil; a = x){ x = a->hash; if(ipcmp(ip, a->ip) == 0) cleanarpent(arp, a); } qunlock(arp); } else error(Ebadarp); return len; } static void convmac(char *p, uchar *mac, int n) { while(n-- > 0) p += sprint(p, "%2.2ux", *mac++); } int arpread(Arp *arp, char *s, ulong offset, int len) { char mac[2*MAClen+1], *state, *mname, *p; uchar ip[IPaddrlen], ia[IPaddrlen]; Ipifc *ifc; Arpent *a; long n, o; p = s; o = -offset; for(a = arp->cache; len > 0 && a < &arp->cache[NCACHE]; a++){ if(a->state == 0 || (ifc = a->ifc) == nil) continue; rlock(ifc); qlock(arp); state = arpstate[a->state]; ipmove(ip, a->ip); if(ifc->m == nil || a->ifcid != ifc->ifcid || !ipv6local(ifc, ia, 0, ip)){ qunlock(arp); runlock(ifc); continue; } mname = ifc->m->name; convmac(mac, a->mac, ifc->m->maclen); qunlock(arp); runlock(ifc); n = snprint(up->genbuf, sizeof up->genbuf, "%-6.6s %-4.4s %-40.40I %-16.16s %I\n", mname, state, ip, mac, ia); o += n; if(o <= 0) continue; if(n > len) break; memmove(p, up->genbuf, n); len -= n; p += n; } return p - s; } void ndpsendsol(Fs *f, Ipifc *ifc, Arpent *a) { uchar targ[IPaddrlen], src[IPaddrlen]; Arpent **l; a->ctime = NOW; if(a->rxtsrem == 0) a->rxtsrem = MAX_MULTICAST_SOLICIT; else a->rxtsrem--; /* put on end of re-transmit chain */ for(l = rxmtunchain(f->arp, a); *l != nil; l = &(*l)->nextrxt) ; *l = a; if(l == &f->arp->rxmt) wakeup(&f->arp->rxmtq); /* try to use source address of original packet */ ipmove(targ, a->ip); if(a->last != nil){ ipmove(src, ((Ip6hdr*)a->last->rp)->src); arprelease(f->arp, a); if(iplocalonifc(ifc, src) != nil || ipproxyifc(f, ifc, src)) goto send; } else { arprelease(f->arp, a); } if(!ipv6local(ifc, src, 0, targ)) return; send: if(!waserror()){ icmpns(f, src, SRC_UNI, targ, TARG_MULTI, ifc->mac); poperror(); } } static void rxmitsols(Arp *arp) { Block *next, *bp; Arpent *a; Ipifc *ifc; Route *r; qlock(arp); while((a = arp->rxmt) != nil && NOW - a->ctime > 3*ReTransTimer/4){ if(a->rxtsrem > 0 && (ifc = a->ifc) != nil && canrlock(ifc)){ if(a->ifcid == ifc->ifcid){ ndpsendsol(arp->f, ifc, a); /* unlocks arp */ runlock(ifc); qlock(arp); continue; } runlock(ifc); } cleanarpent(arp, a); } bp = arp->dropf; arp->dropf = arp->dropl = nil; qunlock(arp); for(; bp != nil; bp = next){ next = bp->list; bp->list = nil; r = v6lookup(arp->f, ((Ip6hdr*)bp->rp)->src, ((Ip6hdr*)bp->rp)->dst, nil); if(r != nil && (ifc = r->ifc) != nil && canrlock(ifc)){ if(!waserror()){ icmphostunr6(arp->f, ifc, bp, Icmp6_adr_unreach, (r->type & Runi) != 0); poperror(); } runlock(ifc); } freeblist(bp); } } static int rxready(void *v) { Arp *arp = (Arp *)v; return arp->rxmt != nil || arp->dropf != nil; } static void rxmitproc(void *v) { Arp *arp = v; arp->rxmitp = up; if(waserror()){ arp->rxmitp = nil; pexit("hangup", 1); } for(;;){ sleep(&arp->rxmtq, rxready, v); rxmitsols(arp); tsleep(&arp->rxmtq, return0, nil, ReTransTimer/4); } }