ref: dbf6aaf513a4dbcc53d938917d47b057adfab81f
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) extern 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; } } /* * create a new arp entry for an ip address. */ static Arpent* newarp6(Arp *arp, uchar *ip, Ipifc *ifc, int addrxt) { uint t; Block *xp; Arpent *a, *e, *f, **l; Medium *m = ifc->m; int empty; /* 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; } } /* dump waiting packets */ xp = a->hold; a->hold = nil; if(isv4(a->ip)) freeblistchain(xp); else { /* queue icmp unreachable for rxmitproc later on, w/o arp lock */ if(xp != nil){ if(arp->dropf == nil) arp->dropf = xp; else arp->dropl->list = xp; arp->dropl = a->last; wakeup(&arp->rxmtq); } } a->last = nil; /* take out of current chain */ l = &arp->hash[haship(a->ip)]; for(f = *l; f != nil; f = f->hash){ if(f == a){ *l = a->hash; break; } l = &f->hash; } /* insert into new chain */ l = &arp->hash[haship(ip)]; a->hash = *l; *l = a; memmove(a->ip, ip, sizeof(a->ip)); a->utime = NOW; a->ctime = 0; a->type = m; a->rtime = NOW + ReTransTimer; a->rxtsrem = MAX_MULTICAST_SOLICIT; a->ifc = ifc; a->ifcid = ifc->ifcid; /* put to the end of re-transmit chain; addrxt is 0 when isv4(a->ip) */ if(!ipismulticast(a->ip) && addrxt){ l = &arp->rxmt; empty = (*l == nil); for(f = *l; f != nil; f = f->nextrxt){ if(f == a){ *l = a->nextrxt; break; } l = &f->nextrxt; } for(f = *l; f != nil; f = f->nextrxt) l = &f->nextrxt; *l = a; if(empty) wakeup(&arp->rxmtq); } a->nextrxt = nil; return a; } /* called with arp qlocked */ static void cleanarpent(Arp *arp, Arpent *a) { Arpent *f, **l; a->utime = 0; a->ctime = 0; a->type = 0; a->state = 0; /* take out of current chain */ l = &arp->hash[haship(a->ip)]; for(f = *l; f != nil; f = f->hash){ if(f == a){ *l = a->hash; break; } l = &f->hash; } /* take out of re-transmit chain */ l = &arp->rxmt; for(f = *l; f != nil; f = f->nextrxt){ if(f == a){ *l = a->nextrxt; break; } l = &f->nextrxt; } a->nextrxt = nil; a->hash = nil; freeblistchain(a->hold); a->hold = a->last = nil; a->ifc = nil; } /* * 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; Medium *type = ifc->m; 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(memcmp(ip, a->ip, sizeof(a->ip)) == 0) if(type == a->type) break; } if(a == nil){ a = newarp6(arp, ip, ifc, (version != V4)); 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, a->type->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; Arpent *f, **l; if(!isv4(a->ip)){ l = &arp->rxmt; for(f = *l; f != nil; f = f->nextrxt){ if(f == a){ *l = a->nextrxt; break; } l = &f->nextrxt; } } memmove(a->mac, mac, type->maclen); a->type = type; a->state = AOK; a->utime = NOW; bp = a->hold; assert(bp->list == nil); a->hold = a->last = nil; qunlock(arp); return bp; } void arpenter(Fs *fs, int version, uchar *ip, uchar *mac, int n, int refresh) { Arp *arp; Route *r; Arpent *a, *f, **l; Ipifc *ifc; Medium *type; Block *bp, *next; uchar v6ip[IPaddrlen]; arp = fs->arp; if(n != 6) return; switch(version){ case V4: r = v4lookup(fs, ip, nil); v4tov6(v6ip, ip); ip = v6ip; break; case V6: r = v6lookup(fs, ip, nil); break; default: panic("arpenter: version %d", version); return; /* to supress warnings */ } if(r == nil) return; ifc = r->ifc; type = ifc->m; qlock(arp); for(a = arp->hash[haship(ip)]; a != nil; a = a->hash){ if(a->type != type || (a->state != AWAIT && a->state != AOK)) continue; if(ipcmp(a->ip, ip) == 0){ a->state = AOK; memmove(a->mac, mac, type->maclen); if(version == V6){ /* take out of re-transmit chain */ l = &arp->rxmt; for(f = *l; f != nil; f = f->nextrxt){ if(f == a){ *l = a->nextrxt; break; } l = &f->nextrxt; } } a->ifc = ifc; a->ifcid = ifc->ifcid; bp = a->hold; a->hold = a->last = nil; if(version == V4) ip += IPv4off; a->utime = NOW; a->ctime = a->utime; qunlock(arp); while(bp != nil){ next = bp->list; if(waserror()){ freeblistchain(next); runlock(ifc); nexterror(); } rlock(ifc); if(ifc->m != nil) ifc->m->bwrite(ifc, concatblock(bp), version, ip); else freeblist(bp); runlock(ifc); poperror(); bp = next; } return; } } if(refresh == 0){ a = newarp6(arp, ip, ifc, 0); a->state = AOK; a->type = type; a->ctime = NOW; memmove(a->mac, mac, type->maclen); } qunlock(arp); } int arpwrite(Fs *fs, char *s, int len) { int n; Route *r; Arp *arp; Arpent *a; Medium *m; char *f[4], buf[256]; uchar ip[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, 4, 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->state = 0; a->utime = 0; freeblistchain(a->hold); a->hold = a->last = nil; } memset(arp->hash, 0, sizeof(arp->hash)); /* clear all pkts on these lists (rxmt, dropf/l) */ arp->rxmt = nil; freeblistchain(arp->dropf); arp->dropf = arp->dropl = 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(isv4(ip)) r = v4lookup(fs, ip+IPv4off, nil); else r = v6lookup(fs, ip, nil); if(r == nil) error("Destination unreachable"); m = r->ifc->m; n = parsemac(mac, f[2], m->maclen); break; case 4: m = ipfindmedium(f[1]); if(m == nil) error(Ebadarp); if (parseip(ip, f[2]) == -1) error(Ebadip); n = parsemac(mac, f[3], m->maclen); break; } if(m->ares == nil) error(Ebadarp); m->ares(fs, V6, ip, mac, n, 0); } 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 = a->hash) if(memcmp(ip, a->ip, sizeof(a->ip)) == 0) break; if(a != nil){ cleanarpent(arp, a); memset(a->ip, 0, sizeof(a->ip)); memset(a->mac, 0, sizeof(a->mac)); } qunlock(arp); } else error(Ebadarp); return len; } enum { Alinelen= 90, }; char *aformat = "%-6.6s %-8.8s %-40.40I %-32.32s\n"; static void convmac(char *p, uchar *mac, int n) { while(n-- > 0) p += sprint(p, "%2.2ux", *mac++); } int arpread(Arp *arp, char *p, ulong offset, int len) { Arpent *a; int n; char mac[2*MAClen+1]; if(offset % Alinelen) return 0; offset = offset/Alinelen; len = len/Alinelen; n = 0; for(a = arp->cache; len > 0 && a < &arp->cache[NCACHE]; a++){ if(a->state == 0) continue; if(offset > 0){ offset--; continue; } len--; qlock(arp); convmac(mac, a->mac, a->type->maclen); n += sprint(p+n, aformat, a->type->name, arpstate[a->state], a->ip, mac); qunlock(arp); } return n; } extern int rxmitsols(Arp *arp) { uint sflag; Block *next, *xp; Arpent *a, *b, **l; Fs *f; uchar ipsrc[IPaddrlen]; Ipifc *ifc = nil; long nrxt; qlock(arp); f = arp->f; a = arp->rxmt; if(a == nil){ nrxt = 0; goto dodrops; /* return nrxt; */ } nrxt = a->rtime - NOW; if(nrxt > 3*ReTransTimer/4) goto dodrops; /* return nrxt; */ for(; a != nil; a = a->nextrxt){ ifc = a->ifc; if(a->rxtsrem > 0 && ifc != nil && canrlock(ifc)){ if(a->ifcid == ifc->ifcid) break; runlock(ifc); } xp = a->hold; a->hold = nil; if(xp != nil){ if(arp->dropf == nil) arp->dropf = xp; else arp->dropl->list = xp; arp->dropl = a->last; } cleanarpent(arp, a); } if(a == nil) goto dodrops; qunlock(arp); /* for icmpns */ if((sflag = ipv6anylocal(ifc, ipsrc)) != SRC_UNSPEC) icmpns(f, ipsrc, sflag, a->ip, TARG_MULTI, ifc->mac); runlock(ifc); qlock(arp); /* put to the end of re-transmit chain */ l = &arp->rxmt; for(b = *l; b != nil; b = b->nextrxt){ if(b == a){ *l = a->nextrxt; break; } l = &b->nextrxt; } for(b = *l; b != nil; b = b->nextrxt) l = &b->nextrxt; *l = a; a->rxtsrem--; a->nextrxt = nil; a->rtime = NOW + ReTransTimer; a = arp->rxmt; if(a == nil) nrxt = 0; else nrxt = a->rtime - NOW; dodrops: xp = arp->dropf; arp->dropf = arp->dropl = nil; qunlock(arp); for(; xp != nil; xp = next){ next = xp->list; icmphostunr(f, ifc, xp, Icmp6_adr_unreach, 1); } return nrxt; } static int rxready(void *v) { Arp *arp = (Arp *) v; return arp->rxmt != nil || arp->dropf != nil; } static void rxmitproc(void *v) { Arp *arp = v; long wakeupat; arp->rxmitp = up; if(waserror()){ arp->rxmitp = nil; pexit("hangup", 1); } for(;;){ wakeupat = rxmitsols(arp); if(wakeupat == 0) sleep(&arp->rxmtq, rxready, v); else if(wakeupat > ReTransTimer/4) tsleep(&arp->rxmtq, return0, 0, wakeupat); } }