r26244: Add a module (sans tests for the moment) that implements ranged

results, as used particularly by MMC's Active Directory Users and
Computers to list group members.

This may be used on any attribute, but is useful to obtain attributes
that may be lengthy in 'pages'.  The implementation presumes that
attributes will always be returned by the DB in the same order.

Andrew Bartlett
(This used to be commit c789a91e00b47b2f02513e97101b9606d00c6aaa)

1 files changed, 204 insertions, 0 deletions

diff --git a/source4/dsdb/samdb/ldb_modules/ranged_results.c b/source4/dsdb/samdb/ldb_modules/ranged_results.c
new file mode 100644
index 0000000000..8f368b6f14
--- /dev/null
+++ b/source4/dsdb/samdb/ldb_modules/ranged_results.c
@@ -0,0 +1,204 @@
+/* 
+   ldb database library
+
+   Copyright (C) Andrew Bartlett 2007
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+   
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+   
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+/*
+ *  Name: ldb
+ *
+ *  Component: ldb ranged results module
+ *
+ *  Description: munge AD-style 'ranged results' requests into
+ *  requests for all values in an attribute, then return the range to
+ *  the client.
+ *
+ *  Author: Andrew Bartlett
+ */
+
+#include "ldb_includes.h"
+
+struct rr_context {
+	struct ldb_request *orig_req;
+	struct ldb_request *down_req;
+};
+
+static int rr_search_callback(struct ldb_context *ldb, void *context, struct ldb_reply *ares) 
+{
+	struct rr_context *rr_context = talloc_get_type(context, struct rr_context);
+	struct ldb_request *orig_req = rr_context->orig_req;
+	int i, j, ret;
+	
+	if (ares->type != LDB_REPLY_ENTRY) {
+		return rr_context->orig_req->callback(ldb, rr_context->orig_req->context, ares);
+	}
+
+	/* Find those that are range requests from the attribute list */
+	for (i = 0; orig_req->op.search.attrs[i]; i++) {
+		char *p, *new_attr;
+		const char *end_str;
+		unsigned int start, end, orig_num_values;
+		struct ldb_message_element *el;
+		struct ldb_val *orig_values;
+		p = strchr(orig_req->op.search.attrs[i], ';');
+		if (!p) {
+			continue;
+		}
+		if (strncasecmp(p, ";range=", strlen(";range=")) != 0) {
+			continue;
+		}
+		if (sscanf(p, ";range=%u-*", &start) == 1) {
+			end = (unsigned int)-1;
+		} else if (sscanf(p, ";range=%u-%u", &start, &end) != 2) {
+			continue;
+		}
+		new_attr = talloc_strndup(orig_req, 
+					  orig_req->op.search.attrs[i],
+					  (unsigned int)(p-orig_req->op.search.attrs[i]));
+
+		if (!new_attr) {
+			ldb_oom(ldb);
+			return LDB_ERR_OPERATIONS_ERROR;
+		}
+		el = ldb_msg_find_element(ares->message, new_attr);
+		talloc_free(new_attr);
+		if (!el) {
+			continue;
+		}
+		if (start > end) {
+			ldb_asprintf_errstring(ldb, "range request error: start must not be greater than end");
+			return LDB_ERR_UNWILLING_TO_PERFORM;
+		}
+		if (end >= el->num_values) {
+			/* Need to leave the requested attribute in
+			 * there (so add an empty one to match) */
+			end_str = "*";
+			end = el->num_values;
+			ret = ldb_msg_add_empty(ares->message, orig_req->op.search.attrs[i], 
+					       0, NULL);
+			if (ret != LDB_SUCCESS) {
+				return ret;
+			}
+		} else {
+			end_str = talloc_asprintf(el, "%u", end);
+		}
+		orig_values = el->values;
+		orig_num_values = el->num_values;
+
+		if ((start + end < start) || (start + end < end)) {
+			ldb_asprintf_errstring(ldb, "range request error: start or end would overflow!");
+			return LDB_ERR_UNWILLING_TO_PERFORM;
+		}
+
+		el->values = talloc_array(el, struct ldb_val, end - start);
+		el->num_values = 0;
+
+		if (!el->values) {
+			ldb_oom(ldb);
+			return LDB_ERR_OPERATIONS_ERROR;
+		}
+		for (j=start; j < end; j++) {
+			el->values[el->num_values] = orig_values[j];
+			el->num_values++;
+		}
+		el->name = talloc_asprintf(el, "%s;Range=%u-%s", el->name, start, end_str);
+		if (!el->name) {
+			ldb_oom(ldb);
+			return LDB_ERR_OPERATIONS_ERROR;
+		}
+	}
+
+	return rr_context->orig_req->callback(ldb, rr_context->orig_req->context, ares);
+
+}
+
+/* search */
+static int rr_search(struct ldb_module *module, struct ldb_request *req)
+{
+	int i;
+	unsigned int start, end;
+	const char **new_attrs = NULL;
+	struct rr_context *context;
+	bool found_rr = false;
+
+	/* Strip the range request from the attribute */
+	for (i = 0; req->op.search.attrs && req->op.search.attrs[i]; i++) {
+		char *p;
+		new_attrs = talloc_realloc(req, new_attrs, const char *, i+2);
+		new_attrs[i] = req->op.search.attrs[i];
+		new_attrs[i+1] = NULL;
+		p = strchr(req->op.search.attrs[i], ';');
+		if (!p) {
+			continue;
+		}
+		if (strncasecmp(p, ";range=", strlen(";range=")) != 0) {
+			continue;
+		}
+		if (sscanf(p, ";range=%u-*", &start) == 1) {
+		} else if (sscanf(p, ";range=%u-%u", &start, &end) != 2) {
+			ldb_asprintf_errstring(module->ldb, "range request error: range requst malformed");
+			return LDB_ERR_UNWILLING_TO_PERFORM;
+		}
+		if (start > end) {
+			ldb_asprintf_errstring(module->ldb, "range request error: start must not be greater than end");
+			return LDB_ERR_UNWILLING_TO_PERFORM;
+		}
+
+		found_rr = true;
+		new_attrs[i] = talloc_strndup(new_attrs, 
+					      req->op.search.attrs[i],
+					      (unsigned int)(p-req->op.search.attrs[i]));
+
+		if (!new_attrs[i]) {
+			ldb_oom(module->ldb);
+			return LDB_ERR_OPERATIONS_ERROR;
+		}
+	}
+
+	if (found_rr) {
+		int ret;
+		context = talloc(req, struct rr_context);
+		context->orig_req = req;
+		context->down_req = talloc(context, struct ldb_request);
+		*context->down_req = *req;
+		
+		context->down_req->op.search.attrs = new_attrs;
+		
+		context->down_req->callback = rr_search_callback;
+		context->down_req->context = context;
+
+		ret = ldb_next_request(module, context->down_req);
+		
+		/* We don't need to implement our own 'wait' function, so pass the handle along */
+		if (ret == LDB_SUCCESS) {
+			req->handle = context->down_req->handle;
+		}
+		return ret;
+	}
+
+	/* No change, just run the original request as if we were never here */
+	return ldb_next_request(module, req);
+}
+
+static const struct ldb_module_ops rr_ops = {
+	.name		   = "ranged_results",
+	.search            = rr_search,
+};
+
+int ldb_ranged_results_init(void)
+{
+	return ldb_register_module(&rr_ops);
+}