radix.c

ReactOS是一些高手根据Windows XP的内核编写出的类XP。内核实现机理和API函数调用几乎相同。甚至可以兼容XP的程序。喜欢研究系统内核的人可以看一看。

struct radix_node *
rn_addroute(v_arg, n_arg, head, treenodes)
	void *v_arg, *n_arg;
	struct radix_node_head *head;
	struct radix_node treenodes[2];
{
	caddr_t v = (caddr_t)v_arg, netmask = (caddr_t)n_arg;
	register struct radix_node *t, *x = 0, *tt;
	struct radix_node *saved_tt, *top = head->rnh_treetop;
	short b = 0, b_leaf = 0;
	int keyduplicated;
	caddr_t mmask;
	struct radix_mask *m, **mp;

	/*
	 * In dealing with non-contiguous masks, there may be
	 * many different routes which have the same mask.
	 * We will find it useful to have a unique pointer to
	 * the mask to speed avoiding duplicate references at
	 * nodes and possibly save time in calculating indices.
	 */
	if (netmask)  {
		if ((x = rn_addmask(netmask, 0, top->rn_off)) == 0)
			return (0);
		b_leaf = x->rn_b;
		b = -1 - x->rn_b;
		netmask = x->rn_key;
	}
	/*
	 * Deal with duplicated keys: attach node to previous instance
	 */
	saved_tt = tt = rn_insert(v, head, &keyduplicated, treenodes);
	if (keyduplicated) {
		for (t = tt; tt; t = tt, tt = tt->rn_dupedkey) {
			if (tt->rn_mask == netmask)
				return (0);
			if (netmask == 0 ||
			    (tt->rn_mask &&
			     ((b_leaf < tt->rn_b) || /* index(netmask) > node */
			       rn_refines(netmask, tt->rn_mask) ||
			       rn_lexobetter(netmask, tt->rn_mask))))
				break;
		}
		/*
		 * If the mask is not duplicated, we wouldn't
		 * find it among possible duplicate key entries
		 * anyway, so the above test doesn't hurt.
		 *
		 * We sort the masks for a duplicated key the same way as
		 * in a masklist -- most specific to least specific.
		 * This may require the unfortunate nuisance of relocating
		 * the head of the list.
		 */
		if (tt == saved_tt) {
			struct	radix_node *xx = x;
			/* link in at head of list */
			(tt = treenodes)->rn_dupedkey = t;
			tt->rn_flags = t->rn_flags;
			tt->rn_p = x = t->rn_p;
			t->rn_p = tt;				/* parent */
			if (x->rn_l == t) x->rn_l = tt; else x->rn_r = tt;
			saved_tt = tt; x = xx;
		} else {
			(tt = treenodes)->rn_dupedkey = t->rn_dupedkey;
			t->rn_dupedkey = tt;
			tt->rn_p = t;				/* parent */
			if (tt->rn_dupedkey)			/* parent */
				tt->rn_dupedkey->rn_p = tt;	/* parent */
		}
#ifdef RN_DEBUG
		t=tt+1; tt->rn_info = rn_nodenum++; t->rn_info = rn_nodenum++;
		tt->rn_twin = t; tt->rn_ybro = rn_clist; rn_clist = tt;
#endif
		tt->rn_key = (caddr_t) v;
		tt->rn_b = -1;
		tt->rn_flags = RNF_ACTIVE;
	}
	/*
	 * Put mask in tree.
	 */
	if (netmask) {
		tt->rn_mask = netmask;
		tt->rn_b = x->rn_b;
		tt->rn_flags |= x->rn_flags & RNF_NORMAL;
	}
	t = saved_tt->rn_p;
	if (keyduplicated)
		goto on2;
	b_leaf = -1 - t->rn_b;
	if (t->rn_r == saved_tt) x = t->rn_l; else x = t->rn_r;
	/* Promote general routes from below */
	if (x->rn_b < 0) {
	    for (mp = &t->rn_mklist; x; x = x->rn_dupedkey)
		if (x->rn_mask && (x->rn_b >= b_leaf) && x->rn_mklist == 0) {
			*mp = m = rn_new_radix_mask(x, 0);
			if (m)
				mp = &m->rm_mklist;
		}
	} else if (x->rn_mklist) {
		/*
		 * Skip over masks whose index is > that of new node
		 */
		for (mp = &x->rn_mklist; (m = *mp); mp = &m->rm_mklist)
			if (m->rm_b >= b_leaf)
				break;
		t->rn_mklist = m; *mp = 0;
	}
on2:
	/* Add new route to highest possible ancestor's list */
	if ((netmask == 0) || (b > t->rn_b ))
		return tt; /* can't lift at all */
	b_leaf = tt->rn_b;
	do {
		x = t;
		t = t->rn_p;
	} while (b <= t->rn_b && x != top);
	/*
	 * Search through routes associated with node to
	 * insert new route according to index.
	 * Need same criteria as when sorting dupedkeys to avoid
	 * double loop on deletion.
	 */
	for (mp = &x->rn_mklist; (m = *mp); mp = &m->rm_mklist) {
		if (m->rm_b < b_leaf)
			continue;
		if (m->rm_b > b_leaf)
			break;
		if (m->rm_flags & RNF_NORMAL) {
			mmask = m->rm_leaf->rn_mask;
			if (tt->rn_flags & RNF_NORMAL) {
				log(LOG_ERR,
				   "Non-unique normal route, mask not entered");
				return tt;
			}
		} else
			mmask = m->rm_mask;
		if (mmask == netmask) {
			m->rm_refs++;
			tt->rn_mklist = m;
			return tt;
		}
		if (rn_refines(netmask, mmask) || rn_lexobetter(netmask, mmask))
			break;
	}
	*mp = rn_new_radix_mask(tt, *mp);
	return tt;
}

struct radix_node *
rn_delete(v_arg, netmask_arg, head)
	void *v_arg, *netmask_arg;
	struct radix_node_head *head;
{
	register struct radix_node *t, *p, *x, *tt;
	struct radix_mask *m, *saved_m, **mp;
	struct radix_node *dupedkey, *saved_tt, *top;
	caddr_t v, netmask;
	int b, head_off, vlen;

	v = v_arg;
	netmask = netmask_arg;
	x = head->rnh_treetop;
	tt = rn_search(v, x);
	head_off = x->rn_off;
	vlen =  *(u_char *)v;
	saved_tt = tt;
	top = x;
	if (tt == 0 ||
	    Bcmp(v + head_off, tt->rn_key + head_off, vlen - head_off))
		return (0);
	/*
	 * Delete our route from mask lists.
	 */
	if (netmask) {
		if ((x = rn_addmask(netmask, 1, head_off)) == 0)
			return (0);
		netmask = x->rn_key;
		while (tt->rn_mask != netmask)
			if ((tt = tt->rn_dupedkey) == 0)
				return (0);
	}
	if (tt->rn_mask == 0 || (saved_m = m = tt->rn_mklist) == 0)
		goto on1;
	if (tt->rn_flags & RNF_NORMAL) {
		if (m->rm_leaf != tt || m->rm_refs > 0) {
			log(LOG_ERR, "rn_delete: inconsistent annotation\n");
			return 0;  /* dangling ref could cause disaster */
		}
	} else {
		if (m->rm_mask != tt->rn_mask) {
			log(LOG_ERR, "rn_delete: inconsistent annotation\n");
			goto on1;
		}
		if (--m->rm_refs >= 0)
			goto on1;
	}
	b = -1 - tt->rn_b;
	t = saved_tt->rn_p;
	if (b > t->rn_b)
		goto on1; /* Wasn't lifted at all */
	do {
		x = t;
		t = t->rn_p;
	} while (b <= t->rn_b && x != top);
	for (mp = &x->rn_mklist; (m = *mp); mp = &m->rm_mklist)
		if (m == saved_m) {
			*mp = m->rm_mklist;
			MKFree(m);
			break;
		}
	if (m == 0) {
		log(LOG_ERR, "rn_delete: couldn't find our annotation\n");
		if (tt->rn_flags & RNF_NORMAL)
			return (0); /* Dangling ref to us */
	}
on1:
	/*
	 * Eliminate us from tree
	 */
	if (tt->rn_flags & RNF_ROOT)
		return (0);
#ifdef RN_DEBUG
	/* Get us out of the creation list */
	for (t = rn_clist; t && t->rn_ybro != tt; t = t->rn_ybro) {}
	if (t) t->rn_ybro = tt->rn_ybro;
#endif
	t = tt->rn_p;
	dupedkey = saved_tt->rn_dupedkey;
	if (dupedkey) {
		/*
		 * at this point, tt is the deletion target and saved_tt
		 * is the head of the dupekey chain
		 */
		if (tt == saved_tt) {
			/* remove from head of chain */
			x = dupedkey; x->rn_p = t;
			if (t->rn_l == tt) t->rn_l = x; else t->rn_r = x;
		} else {
			/* find node in front of tt on the chain */
			for (x = p = saved_tt; p && p->rn_dupedkey != tt;)
				p = p->rn_dupedkey;
			if (p) {
				p->rn_dupedkey = tt->rn_dupedkey;
				if (tt->rn_dupedkey)		   /* parent */
					tt->rn_dupedkey->rn_p = p; /* parent */
			} else log(LOG_ERR, "rn_delete: couldn't find us\n");
		}
		t = tt + 1;
		if  (t->rn_flags & RNF_ACTIVE) {
#ifndef RN_DEBUG
			*++x = *t; p = t->rn_p;
#else
			b = t->rn_info; *++x = *t; t->rn_info = b; p = t->rn_p;
#endif
			if (p->rn_l == t) p->rn_l = x; else p->rn_r = x;
			x->rn_l->rn_p = x; x->rn_r->rn_p = x;
		}
		goto out;
	}
	if (t->rn_l == tt) x = t->rn_r; else x = t->rn_l;
	p = t->rn_p;
	if (p->rn_r == t) p->rn_r = x; else p->rn_l = x;
	x->rn_p = p;
	/*
	 * Demote routes attached to us.
	 */
	if (t->rn_mklist) {
		if (x->rn_b >= 0) {
			for (mp = &x->rn_mklist; (m = *mp);)
				mp = &m->rm_mklist;
			*mp = t->rn_mklist;
		} else {
			/* If there are any key,mask pairs in a sibling
			   duped-key chain, some subset will appear sorted
			   in the same order attached to our mklist */
			for (m = t->rn_mklist; m && x; x = x->rn_dupedkey)
				if (m == x->rn_mklist) {
					struct radix_mask *mm = m->rm_mklist;
					x->rn_mklist = 0;
					if (--(m->rm_refs) < 0)
						MKFree(m);
					m = mm;
				}
			if (m)
				log(LOG_ERR, "%s %p at %x\n",
					    "rn_delete: Orphaned Mask", m, x);
		}
	}
	/*
	 * We may be holding an active internal node in the tree.
	 */
	x = tt + 1;
	if (t != x) {
#ifndef RN_DEBUG
		*t = *x;
#else
		b = t->rn_info; *t = *x; t->rn_info = b;
#endif
		t->rn_l->rn_p = t; t->rn_r->rn_p = t;
		p = x->rn_p;
		if (p->rn_l == x) p->rn_l = t; else p->rn_r = t;
	}
out:
	tt->rn_flags &= ~RNF_ACTIVE;
	tt[1].rn_flags &= ~RNF_ACTIVE;
	return (tt);
}

/*
 * This is the same as rn_walktree() except for the parameters and the
 * exit.
 */
int
rn_walktree_from(h, a, m, f, w)
	struct radix_node_head *h;
	void *a, *m;
	register int (*f)();
	void *w;
{
	int error;
	struct radix_node *base, *next;
	u_char *xa = (u_char *)a;
	u_char *xm = (u_char *)m;
	register struct radix_node *rn, *last = 0 /* shut up gcc */;
	int stopping = 0;
	int lastb;

	/*
	 * rn_search_m is sort-of-open-coded here.
	 */
	/* printf("about to search\n"); */
	for (rn = h->rnh_treetop; rn->rn_b >= 0; ) {
		last = rn;
		/* printf("rn_b %d, rn_bmask %x, xm[rn_off] %x\n",
		       rn->rn_b, rn->rn_bmask, xm[rn->rn_off]); */
		if (!(rn->rn_bmask & xm[rn->rn_off])) {
			break;
		}
		if (rn->rn_bmask & xa[rn->rn_off]) {
			rn = rn->rn_r;
		} else {
			rn = rn->rn_l;
		}
	}
	/* printf("done searching\n"); */

	/*
	 * Two cases: either we stepped off the end of our mask,
	 * in which case last == rn, or we reached a leaf, in which
	 * case we want to start from the last node we looked at.
	 * Either way, last is the node we want to start from.
	 */
	rn = last;
	lastb = rn->rn_b;

	/* printf("rn %p, lastb %d\n", rn, lastb);*/

	/*
	 * This gets complicated because we may delete the node
	 * while applying the function f to it, so we need to calculate
	 * the successor node in advance.
	 */
	while (rn->rn_b >= 0)
		rn = rn->rn_l;

	while (!stopping) {
		/* printf("node %p (%d)\n", rn, rn->rn_b); */
		base = rn;
		/* If at right child go back up, otherwise, go right */
		while (rn->rn_p->rn_r == rn && !(rn->rn_flags & RNF_ROOT)) {
			rn = rn->rn_p;

			/* if went up beyond last, stop */
			if (rn->rn_b < lastb) {
				stopping = 1;
				/* printf("up too far\n"); */
			}
		}

		/* Find the next *leaf* since next node might vanish, too */
		for (rn = rn->rn_p->rn_r; rn->rn_b >= 0;)
			rn = rn->rn_l;
		next = rn;
		/* Process leaves */
		while ((rn = base) != 0) {
			base = rn->rn_dupedkey;
			/* printf("leaf %p\n", rn); */
			if (!(rn->rn_flags & RNF_ROOT)
			    && (error = (*f)(rn, w)))
				return (error);
		}
		rn = next;

		if (rn->rn_flags & RNF_ROOT) {
			/* printf("root, stopping"); */
			stopping = 1;
		}

	}
	return 0;
}

int
rn_walktree(h, f, w)
	struct radix_node_head *h;
	register int (*f)();
	void *w;
{
	int error;
	struct radix_node *base, *next;
	register struct radix_node *rn = h->rnh_treetop;
	/*
	 * This gets complicated because we may delete the node
	 * while applying the function f to it, so we need to calculate
	 * the successor node in advance.
	 */
	/* First time through node, go left */
	while (rn->rn_b >= 0)
		rn = rn->rn_l;
	for (;;) {
		base = rn;
		/* If at right child go back up, otherwise, go right */
		while (rn->rn_p->rn_r == rn && (rn->rn_flags & RNF_ROOT) == 0)
			rn = rn->rn_p;
		/* Find the next *leaf* since next node might vanish, too */
		for (rn = rn->rn_p->rn_r; rn->rn_b >= 0;)
			rn = rn->rn_l;
		next = rn;
		/* Process leaves */
		while ((rn = base)) {
			base = rn->rn_dupedkey;
			if (!(rn->rn_flags & RNF_ROOT) && (error = (*f)(rn, w)))
				return (error);
		}
		rn = next;
		if (rn->rn_flags & RNF_ROOT)
			return (0);
	}
	/* NOTREACHED */
}

int
rn_inithead(head, off)
	void **head;
	int off;
{
	register struct radix_node_head *rnh;
	register struct radix_node *t, *tt, *ttt;
	if (*head)
		return (1);
	R_Malloc(rnh, struct radix_node_head *, sizeof (*rnh));
	if (rnh == 0)
		return (0);
	Bzero(rnh, sizeof (*rnh));
	*head = rnh;
	t = rn_newpair(rn_zeros, off, rnh->rnh_nodes);
	ttt = rnh->rnh_nodes + 2;
	t->rn_r = ttt;
	t->rn_p = t;
	tt = t->rn_l;
	tt->rn_flags = t->rn_flags = RNF_ROOT | RNF_ACTIVE;
	tt->rn_b = -1 - off;
	*ttt = *tt;
	ttt->rn_key = rn_ones;
	rnh->rnh_addaddr = rn_addroute;
	rnh->rnh_deladdr = rn_delete;
	rnh->rnh_matchaddr = rn_match;
	rnh->rnh_lookup = rn_lookup;
	rnh->rnh_walktree = rn_walktree;
	rnh->rnh_walktree_from = rn_walktree_from;
	rnh->rnh_treetop = t;
	return (1);
}

void
rn_init()
{
	char *cp, *cplim;
#ifdef KERNEL
	struct domain *dom;

	for (dom = domains; dom; dom = dom->dom_next)
		if (dom->dom_maxrtkey > max_keylen)
			max_keylen = dom->dom_maxrtkey;
#endif
	if (max_keylen == 0) {
		log(LOG_ERR,
		    "rn_init: radix functions require max_keylen be set\n");
		return;
	}
	R_Malloc(rn_zeros, char *, 3 * max_keylen);
	if (rn_zeros == NULL)
		panic("rn_init");
	Bzero(rn_zeros, 3 * max_keylen);
	rn_ones = cp = rn_zeros + max_keylen;
	addmask_key = cplim = rn_ones + max_keylen;
	while (cp < cplim)
		*cp++ = -1;
	if (rn_inithead((void **)&mask_rnhead, 0) == 0)
		panic("rn_init 2");
}