VPP-1027: DNS name resolver

This patch is a plausible first-cut, suitable for initial testing by
vcl (host stack client library).

Main features;
- recursive name resolution
- multiple ip4/ip6 name servers
- cache size limit enforcement
  - currently limited to 65K
- ttl / aging
- static mapping support
- show / clear / debug CLI commands

Binary APIs provided for the following:
- add/delete name servers
- enable/disable the name cache
- resolve a name

To Do list:
- Respond to ip4/ip6 client DNS requests (vs. binary API requests)
- Perf / scale tuning
  - map pending transaction ids to pool indices, so the cache
    can (greatly) exceed 65K entries
- Security improvements
  - Use unpredictable dns transaction IDs, related to previous item
  - Make sure that response-packet src ip addresses match the server
- Add binary APIs
  - deliver raw response data to clients
  - control recursive name resolution
- Documentation

Change-Id: I48c373d5c05d7108ccd814d4055caf8c75ca10b7
Signed-off-by: Dave Barach <dave@barachs.net>

1 files changed, 66 insertions, 0 deletions

diff --git a/src/vnet/dns/dns.api b/src/vnet/dns/dns.api
new file mode 100644
index 00000000000..55574458ddd
--- /dev/null
+++ b/src/vnet/dns/dns.api
@@ -0,0 +1,66 @@
+/*
+ * Copyright (c) 2017 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+ 
+vl_api_version 1.0.0
+
+/** \brief enable/disable name resolution
+
+    @param client_index - opaque cookie to identify the sender
+    @param context - sender context, to match reply w/ request
+    @param is_enable - 1 = enable, 0 = disable
+*/
+autoreply define dns_enable_disable {
+    u32 client_index;
+    u32 context;
+    u8 enable;
+};
+
+/** \brief add or delete an upstream name server
+
+    @param client_index - opaque cookie to identify the sender
+    @param context - sender context, to match reply w/ request
+    @param is_ip6 - an ip6 name server
+    @param is_add - add = 1, delete = 0
+    @param server_address - server ip address
+*/
+autoreply define dns_name_server_add_del {
+    u32 client_index;
+    u32 context;
+    u8 is_ip6;
+    u8 is_add;
+    u8 server_address[16];
+};
+
+/** \brief DNS name resolution request
+
+    @param client_index - opaque cookie to identify the sender
+    @param context - sender context, to match reply w/ request
+    @param name - the name to resolve
+*/
+define dns_resolve_name {
+    u32 client_index;
+    u32 context;
+    u8 name[128];
+ };
+
+define dns_resolve_name_reply {
+    u32 context;
+    i32 retval;
+    u8 ip4_set;
+    u8 ip6_set;
+    u8 ip4_address[4];
+    u8 ip6_address[16];
+};
+