rbt.c

bind 9.3结合mysql数据库

				 * this is the only real use of chains in the
				 * function.  It could be done instead with
				 * a simple integer variable, but I am pressed
				 * for time.
				 */
				if (chain.level_count ==
				    (sizeof(chain.levels) /
				     sizeof(*chain.levels))) {
					result = ISC_R_NOSPACE;
					break;
				}

				/*
				 * Split the name into two parts, a prefix
				 * which is the not-in-common parts of the
				 * two names and a suffix that is the common
				 * parts of them.
				 */
				dns_name_split(&current_name, common_labels,
					       prefix, suffix);
				result = create_node(rbt->mctx, suffix,
						     &new_current);

				if (result != ISC_R_SUCCESS)
					break;

				/*
				 * Reproduce the tree attributes of the
				 * current node.
				 */
				new_current->is_root = current->is_root;
				PARENT(new_current)  = PARENT(current);
				LEFT(new_current)    = LEFT(current);
				RIGHT(new_current)   = RIGHT(current);
				COLOR(new_current)   = COLOR(current);

				/*
				 * Fix pointers that were to the current node.
				 */
				if (parent != NULL) {
					if (LEFT(parent) == current)
						LEFT(parent) = new_current;
					else
						RIGHT(parent) = new_current;
				}
				if (LEFT(new_current) != NULL)
					PARENT(LEFT(new_current)) =
						new_current;
				if (RIGHT(new_current) != NULL)
					PARENT(RIGHT(new_current)) =
						new_current;
				if (*root == current)
					*root = new_current;

				NAMELEN(current) = prefix->length;
				OFFSETLEN(current) = prefix->labels;
				memcpy(OFFSETS(current), prefix->offsets,
				       prefix->labels);
				PADBYTES(current) +=
				       (current_name.length - prefix->length) +
				       (current_name.labels - prefix->labels);

				/*
				 * Set up the new root of the next level.
				 * By definition it will not be the top
				 * level tree, so clear DNS_NAMEATTR_ABSOLUTE.
				 */
				current->is_root = 1;
				PARENT(current) = new_current;
				DOWN(new_current) = current;
				root = &DOWN(new_current);

				ADD_LEVEL(&chain, new_current);

				LEFT(current) = NULL;
				RIGHT(current) = NULL;

				MAKE_BLACK(current);
				ATTRS(current) &= ~DNS_NAMEATTR_ABSOLUTE;

				rbt->nodecount++;
				hash_node(rbt, new_current);

				if (common_labels ==
				    dns_name_countlabels(add_name)) {
					/*
					 * The name has been added by pushing
					 * the not-in-common parts down to
					 * a new level.
					 */
					*nodep = new_current;
					return (ISC_R_SUCCESS);

				} else {
					/*
					 * The current node has no data,
					 * because it is just a placeholder.
					 * Its data pointer is already NULL
					 * from create_node()), so there's
					 * nothing more to do to it.
					 */

					/*
					 * The not-in-common parts of the new
					 * name will be inserted into the new
					 * level following this loop (unless
					 * result != ISC_R_SUCCESS, which
					 * is tested after the loop ends).
					 */
					dns_name_split(add_name, common_labels,
						       add_name, NULL);

					break;
				}

			}

		}

	} while (child != NULL);

	if (result == ISC_R_SUCCESS)
		result = create_node(rbt->mctx, add_name, &new_current);

	if (result == ISC_R_SUCCESS) {
		dns_rbt_addonlevel(new_current, current, order, root);
		rbt->nodecount++;
		*nodep = new_current;
		hash_node(rbt, new_current);
	}

	return (result);
}

/*
 * Add a name to the tree of trees, associating it with some data.
 */
isc_result_t
dns_rbt_addname(dns_rbt_t *rbt, dns_name_t *name, void *data) {
	isc_result_t result;
	dns_rbtnode_t *node;

	REQUIRE(VALID_RBT(rbt));
	REQUIRE(dns_name_isabsolute(name));

	node = NULL;

	result = dns_rbt_addnode(rbt, name, &node);

	/*
	 * dns_rbt_addnode will report the node exists even when
	 * it does not have data associated with it, but the
	 * dns_rbt_*name functions all behave depending on whether
	 * there is data associated with a node.
	 */
	if (result == ISC_R_SUCCESS ||
	    (result == ISC_R_EXISTS && DATA(node) == NULL)) {
		DATA(node) = data;
		result = ISC_R_SUCCESS;
	}

	return (result);
}

/*
 * Find the node for "name" in the tree of trees.
 */
isc_result_t
dns_rbt_findnode(dns_rbt_t *rbt, dns_name_t *name, dns_name_t *foundname,
		 dns_rbtnode_t **node, dns_rbtnodechain_t *chain,
		 unsigned int options, dns_rbtfindcallback_t callback,
		 void *callback_arg)
{
	dns_rbtnode_t *current, *last_compared, *current_root;
	dns_rbtnodechain_t localchain;
	dns_name_t *search_name, current_name, *callback_name;
	dns_fixedname_t fixedcallbackname, fixedsearchname;
	dns_namereln_t compared;
	isc_result_t result, saved_result;
	unsigned int common_labels;
	int order;

	REQUIRE(VALID_RBT(rbt));
	REQUIRE(dns_name_isabsolute(name));
	REQUIRE(node != NULL && *node == NULL);
	REQUIRE((options & (DNS_RBTFIND_NOEXACT | DNS_RBTFIND_NOPREDECESSOR))
		!=         (DNS_RBTFIND_NOEXACT | DNS_RBTFIND_NOPREDECESSOR));

	/*
	 * If there is a chain it needs to appear to be in a sane state,
	 * otherwise a chain is still needed to generate foundname and
	 * callback_name.
	 */
	if (chain == NULL) {
		options |= DNS_RBTFIND_NOPREDECESSOR;
		chain = &localchain;
		dns_rbtnodechain_init(chain, rbt->mctx);
	} else
		dns_rbtnodechain_reset(chain);

	if (rbt->root == NULL)
		return (ISC_R_NOTFOUND);
	else {
		/*
		 * Appease GCC about variables it incorrectly thinks are
		 * possibly used uninitialized.
		 */
		compared = dns_namereln_none;
		last_compared = NULL;
	}

	dns_fixedname_init(&fixedcallbackname);
	callback_name = dns_fixedname_name(&fixedcallbackname);

	/*
	 * search_name is the name segment being sought in each tree level.
	 * By using a fixedname, the search_name will definitely have offsets
	 * for use by any splitting.
	 * By using dns_name_clone, no name data should be copied thanks to
	 * the lack of bitstring labels.
	 */
	dns_fixedname_init(&fixedsearchname);
	search_name = dns_fixedname_name(&fixedsearchname);
	dns_name_clone(name, search_name);

	dns_name_init(&current_name, NULL);

	saved_result = ISC_R_SUCCESS;
	current = rbt->root;
	current_root = rbt->root;

	while (current != NULL) {
		NODENAME(current, &current_name);
		compared = dns_name_fullcompare(search_name, &current_name,
						&order, &common_labels);
		last_compared = current;

		if (compared == dns_namereln_equal)
			break;

		if (compared == dns_namereln_none) {
#ifdef DNS_RBT_USEHASH
			dns_name_t hash_name;
			dns_rbtnode_t *hnode;
			dns_rbtnode_t *up_current;
			unsigned int nlabels;
			unsigned int tlabels = 1;
			unsigned int hash;

			/*
			 * If there is no hash table, hashing can't be done.
			 */
			if (rbt->hashtable == NULL)
				goto nohash;

			/*
			 * The case of current != current_root, that
			 * means a left or right pointer was followed,
			 * only happens when the algorithm fell through to
			 * the traditional binary search because of a
			 * bitstring label.  Since we dropped the bitstring
			 * support, this should not happen.
			 */
			INSIST(current == current_root);

			nlabels = dns_name_countlabels(search_name);

			/*
			 * current_root is the root of the current level, so
			 * it's parent is the same as it's "up" pointer.
			 */
			up_current = PARENT(current_root);
			dns_name_init(&hash_name, NULL);

		hashagain:
			dns_name_getlabelsequence(search_name,
						  nlabels - tlabels,
						  tlabels, &hash_name);
			hash = HASHVAL(up_current) +
			       dns_name_hashbylabel(&hash_name, ISC_FALSE);

			for (hnode = rbt->hashtable[hash % rbt->hashsize];
			     hnode != NULL;
			     hnode = hnode->hashnext)
			{
				dns_name_t hnode_name;

				if (hash != HASHVAL(hnode))
					continue;
				if (find_up(hnode) != up_current)
					continue;
				dns_name_init(&hnode_name, NULL);
				NODENAME(hnode, &hnode_name);
				if (dns_name_equal(&hnode_name, &hash_name))
					break;
			}

			if (hnode != NULL) {
				current = hnode;
				/*
				 * This is an optimization.  If hashing found
				 * the right node, the next call to
				 * dns_name_fullcompare() would obviously
				 * return _equal or _subdomain.  Determine
				 * which of those would be the case by
				 * checking if the full name was hashed.  Then
				 * make it look like dns_name_fullcompare
				 * was called and jump to the right place.
				 */
				if (tlabels == nlabels) {
					compared = dns_namereln_equal;
					break;
				} else {
					common_labels = tlabels;
					compared = dns_namereln_subdomain;
					goto subdomain;
				}
			}

			if (tlabels++ < nlabels)
				goto hashagain;

			/*
			 * All of the labels have been tried against the hash
			 * table.  Since we dropped the support of bitstring
			 * labels, the name isn't in the table.
			 */
			current = NULL;
			continue;
			    
		nohash:
#endif /* DNS_RBT_USEHASH */
			/*
			 * Standard binary search tree movement.
			 */
			if (order < 0)
				current = LEFT(current);
			else
				current = RIGHT(current);

		} else {
			/*
			 * The names have some common suffix labels.
			 *
			 * If the number in common are equal in length to
			 * the current node's name length, then follow the
			 * down pointer and search in the new tree.
			 */
			if (compared == dns_namereln_subdomain) {
		subdomain:
				/*
				 * Whack off the current node's common parts
				 * for the name to search in the next level.
				 */
				dns_name_split(search_name, common_labels,
					       search_name, NULL);
				/*
				 * This might be the closest enclosing name.
				 */
				if (DATA(current) != NULL ||
				    (options & DNS_RBTFIND_EMPTYDATA) != 0)
					*node = current;

				/*
				 * Point the chain to the next level.   This
				 * needs to be done before 'current' is pointed
				 * there because the callback in the next
				 * block of code needs the current 'current',
				 * but in the event the callback requests that
				 * the search be stopped then the
				 * DNS_R_PARTIALMATCH code at the end of this
				 * function needs the chain pointed to the
				 * next level.
				 */
				ADD_LEVEL(chain, current);

				/*
				 * The caller may want to interrupt the
				 * downward search when certain special nodes
				 * are traversed.  If this is a special node,
				 * the callback is used to learn what the
				 * caller wants to do.
				 */
				if (callback != NULL &&
				    FINDCALLBACK(current)) {
					result = chain_name(chain,
							    callback_name,
							    ISC_FALSE);
					if (result != ISC_R_SUCCESS) {
						dns_rbtnodechain_reset(chain);
						return (result);
					}

					result = (callback)(current,
							    callback_name,
							    callback_arg);
					if (result != DNS_R_CONTINUE) {
						saved_result = result;
						/*
						 * Treat this node as if it
						 * had no down pointer.
						 */
						current = NULL;
						break;
					}
				}

				/*
				 * Finally, head to the next tree level.
				 */
				current = DOWN(current);
				current_root = current;

			} else {
				/*
				 * Though there are labels in common, the
				 * entire name at this node is not common
				 * with the search name so the search
				 * name does not exist in the tree.
				 */
				INSIST(compared == dns_namereln_commonancestor
				       || compared == dns_namereln_contains);

				current = NULL;
			}
		}
	}

	/*
	 * If current is not NULL, NOEXACT is not disallowing exact matches,
	 * and either the node has data or an empty node is ok, return
	 * ISC_R_SUCCESS to indicate an exact match.
	 */
	if (current != NULL && (options & DNS_RBTFIND_NOEXACT) == 0 &&
	    (DATA(current) != NULL ||
	     (options & DNS_RBTFIND_EMPTYDATA) != 0)) {
		/*
		 * Found an exact match.
		 */
		chain->end = current;
		chain->level_matches = chain->level_count;

		if (foundname != NULL)
			result = chain_name(chain, foundname, ISC_TRUE);
		else
			result = ISC_R_SUCCESS;

		if (result == ISC_R_SUCCESS) {
			*node = current;
			result = saved_result;
		} else
			*node = NULL;
	} else {
		/*
		 * Did not find an exact match (or did not want one).
		 */
		if (*node != NULL) {
			/*
			 * ... but found a partially matching superdomain.
			 * Unwind the chain to the partial match node
			 * to set level_matches to the level above the node,
			 * and then to derive the name.
			 *
			 * chain->level_count is guaranteed to be at least 1
			 * here because by definition of finding a superdomain,
			 * the chain is pointed to at least the first subtree.
			 */
			chain->level_matches = chain->level_count - 1;

			while (chain->levels[chain->level_matches] != *node) {
				INSIST(chain->level_matches > 0);
				chain->level_matches--;
			}

			if (foundname != NULL) {
				unsigned int saved_count = chain->level_count;

				chain->level_count = chain->level_matches + 1;

				result = chain_name(chain, foundname,
						    ISC_FALSE);

				chain->level_count = saved_count;
			} else
				result = ISC_R_SUCCESS;

			if (result == ISC_R_SUCCESS)
				result = DNS_R_PARTIALMATCH;

		} else
			result = ISC_R_NOTFOUND;

		if (current != NULL) {
			/*
			 * There was an exact match but either
			 * DNS_RBTFIND_NOEXACT was set, or
			 * DNS_RBTFIND_EMPTYDATA was set and the node had no
			 * data.  A policy decision was made to set the
			 * chain to the exact match, but this is subject
			 * to change if it becomes apparent that something
			 * else would be more useful.  It is important that
			 * this case is handled here, because the predecessor
			 * setting code below assumes the match was not exact.
			 */
			INSIST(((options & DNS_RBTFIND_NOEXACT) != 0) ||
			       ((options & DNS_RBTFIND_EMPTYDATA) == 0 &&
				DATA(current) == NULL));
			chain->end = current;