Router: fixed crash when matching an empty address pattern array.

A crash would occur when the router tried to match an
against an empty address pattern array.

The following configuration was used to reproduce the
issue:

{
    "listeners": {
        "127.0.0.1:8082": {
            "pass": "routes"
        }
    },
    "routes": [
        {
            "match": {
                "source": []
            },
            "action": {
                "return": 200
            }
        }
    ]
}

3 files changed, 16 insertions, 0 deletions

diff --git a/docs/changes.xml b/docs/changes.xml
index 63c52633..e183f907 100644
--- a/docs/changes.xml
+++ b/docs/changes.xml
@@ -99,6 +99,13 @@ or "upstreams" using a variable "pass" option.
 </para>
 </change>
 
+<change type="bugfix">
+<para>
+the router process crashed while matching a request to an empty array of
+source or destination address patterns.
+</para>
+</change>
+
 </changes>
 
 
diff --git a/src/nxt_http_route.c b/src/nxt_http_route.c
index 065b3488..b330796f 100644
--- a/src/nxt_http_route.c
+++ b/src/nxt_http_route.c
@@ -1936,6 +1936,11 @@ nxt_http_route_addr_rule(nxt_http_request_t *r,
     nxt_http_route_addr_pattern_t  *p;
 
     n = addr_rule->items;
+
+    if (n == 0) {
+        return 0;
+    }
+
     p = &addr_rule->addr_pattern[0] - 1;
 
     do {
diff --git a/test/test_routing.py b/test/test_routing.py
index eaa0a134..ef5622c2 100644
--- a/test/test_routing.py
+++ b/test/test_routing.py
@@ -1751,6 +1751,10 @@ class TestRouting(TestApplicationProto):
         self.route_match_invalid({"source": "*:1-a"})
         self.route_match_invalid({"source": "*:65536"})
 
+    def test_routes_match_source_none(self):
+        self.route_match({"source": []})
+        assert self.get()['status'] == 404, 'source none'
+
     def test_routes_match_destination(self):
         assert 'success' in self.conf(
             {"*:7080": {"pass": "routes"}, "*:7081": {"pass": "routes"}},