From: Evan Hunt <each@isc.org>
Date: Sat, 22 Feb 2020 01:22:06 +0000 (-0800)
Subject: check size ratio when responding to IXFR requests
X-Git-Tag: v9.17.1~71^2~3
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=cb02219b6c7517b534ef4892f9be1807f5be3e0b;p=thirdparty%2Fbind9.git

check size ratio when responding to IXFR requests
---

diff --git a/lib/ns/xfrout.c b/lib/ns/xfrout.c
index eb8b4910331..4178f9293ec 100644
--- a/lib/ns/xfrout.c
+++ b/lib/ns/xfrout.c
@@ -227,10 +227,10 @@ static rrstream_methods_t ixfr_rrstream_methods;
 
 static isc_result_t
 ixfr_rrstream_create(isc_mem_t *mctx, const char *journal_filename,
-		     uint32_t begin_serial, uint32_t end_serial,
+		     uint32_t begin_serial, uint32_t end_serial, size_t *sizep,
 		     rrstream_t **sp) {
-	ixfr_rrstream_t *s;
 	isc_result_t result;
+	ixfr_rrstream_t *s = NULL;
 
 	INSIST(sp != NULL && *sp == NULL);
 
@@ -243,7 +243,7 @@ ixfr_rrstream_create(isc_mem_t *mctx, const char *journal_filename,
 	CHECK(dns_journal_open(mctx, journal_filename, DNS_JOURNAL_READ,
 			       &s->journal));
 	CHECK(dns_journal_iter_init(s->journal, begin_serial, end_serial,
-				    NULL));
+				    sizep));
 
 	*sp = (rrstream_t *)s;
 	return (ISC_R_SUCCESS);
@@ -963,6 +963,9 @@ got_soa:
 
 	current_serial = dns_soa_getserial(&current_soa_tuple->rdata);
 	if (reqtype == dns_rdatatype_ixfr) {
+		size_t jsize;
+		uint64_t dbsize;
+
 		/*
 		 * Outgoing IXFR may have been disabled for this peer
 		 * or globally.
@@ -1008,7 +1011,7 @@ got_soa:
 		if (journalfile != NULL) {
 			result = ixfr_rrstream_create(
 				mctx, journalfile, begin_serial, current_serial,
-				&data_stream);
+				&jsize, &data_stream);
 		} else {
 			result = ISC_R_NOTFOUND;
 		}
@@ -1021,6 +1024,32 @@ got_soa:
 			goto axfr_fallback;
 		}
 		CHECK(result);
+
+		result = dns_db_getsize(db, ver, NULL, &dbsize);
+		if (result == ISC_R_SUCCESS) {
+			uint32_t ratio = dns_zone_getixfrratio(zone);
+			if (ratio != 0 && ((100 * jsize) / dbsize) > ratio) {
+				data_stream->methods->destroy(&data_stream);
+				data_stream = NULL;
+				xfrout_log1(client, question_name,
+					    question_class, ISC_LOG_DEBUG(4),
+					    "IXFR delta size (%zu bytes) "
+					    "exceeds the maximum ratio to "
+					    "database size "
+					    "(%" PRIu64 " bytes), "
+					    "falling back to AXFR",
+					    jsize, dbsize);
+				mnemonic = "AXFR-style IXFR";
+				goto axfr_fallback;
+			} else {
+				xfrout_log1(client, question_name,
+					    question_class, ISC_LOG_DEBUG(4),
+					    "IXFR delta size (%zu bytes); "
+					    "database size "
+					    "(%" PRIu64 " bytes)",
+					    jsize, dbsize);
+			}
+		}
 		is_ixfr = true;
 	} else {
 	axfr_fallback: