listener: add support for multiple filter chains. (#3217)

* listener: add support for multiple filter chains.

*Risk Level*: Medium
*Testing*: bazel test //test/...
*Docs Changes*: Added
*Release Notes*: Added

Fixes #1843.

Signed-off-by: Piotr Sikora <piotrsikora@google.com>

Mirrored from https://github.com/envoyproxy/envoy @ 93780c1663a89c596e46a43ff17cffc25bb00b18

envoy/api/v2/lds.proto

@@ -55,15 +55,8 @@ message Listener {
   // :ref:`FilterChainMatch <envoy_api_msg_listener.FilterChainMatch>` criteria is used on a
   // connection.
   //
-  // .. attention::
-  //
-  //   In the current version, multiple filter chains are supported **only** so that SNI can be
-  //   configured. See the :ref:`FAQ entry <faq_how_to_setup_sni>` on how to configure SNI for more
-  //   information. When multiple filter chains are configured, each filter chain must have an
-  //   **identical** set of :ref:`filters <envoy_api_field_listener.FilterChain.filters>`. If the
-  //   filters differ, the configuration will fail to load. In the future, this limitation will be
-  //   relaxed such that different filters can be used depending on which filter chain matches
-  //   (based on SNI or some other parameter).
+  // Example using SNI for filter chain selection can be found in the
+  // :ref:`FAQ entry <faq_how_to_setup_sni>`.
   repeated listener.FilterChain filter_chains = 3
       [(validate.rules).repeated .min_items = 1, (gogoproto.nullable) = false];
 

envoy/api/v2/listener/listener.proto

@@ -47,12 +47,32 @@ message Filter {
 
 // Specifies the match criteria for selecting a specific filter chain for a
 // listener.
+//
+// In order for a filter chain to be selected, *ALL* of its criteria must be
+// fulfilled by the incoming connection, properties of which are set by the
+// networking stack and/or listener filters.
+//
+// The following order applies:
+//
+// [#comment:TODO(PiotrSikora): destination IP / ranges are going to be 1.]
+// 1. Server name (e.g. SNI for TLS protocol),
+// 2. Transport protocol.
+// [#comment:TODO(PiotrSikora): application protocols are going to be 4.]
+//
+// For criterias that allow ranges or wildcards, the most specific value in any
+// of the configured filter chains that matches the incoming connection is going
+// to be used (e.g. for SNI ``www.example.com`` the most specific match would be
+// ``www.example.com``, then ``*.example.com``, then any filter chain without
+// ``sni_domains`` requirements).
+//
+// [#comment:TODO(PiotrSikora): Add support for configurable precedence of the rules]
 message FilterChainMatch {
   // If non-empty, the SNI domain names to consider. May contain a wildcard prefix for
-  // the bottom-level domain of a domain name, e.g. ``*.example.com``. Note that
-  // ``foo.example.com`` will be matched by ``foo.example.com`` and ``*.example.com``
-  // SNI domain names, but **not** by ``*foo.example.com``, ``*oo.example.com``,
-  // ``*example.com``, ``*.com`` or ``*``.
+  // the bottom-level domain of a domain name, e.g. ``*.example.com``.
+  //
+  // Note that ``foo.example.com`` will be matched by ``foo.example.com``
+  // and ``*.example.com`` SNI domain names, but **not** by ``*foo.example.com``,
+  // ``*oo.example.com``, ``*example.com``, ``*.com`` or ``*``.
   //
   // .. attention::
   //
@@ -90,6 +110,17 @@ message FilterChainMatch {
   // listener in determining a filter chain match.
   // [#not-implemented-hide:]
   google.protobuf.UInt32Value destination_port = 8;
+
+  // If non-empty, a transport protocol to consider when determining a filter chain match.
+  // This value will be compared against the transport protocol of a new connection, when
+  // it's detected by one of the listener filters (this needs to be configured separately).
+  //
+  // Valid values include:
+  //
+  // * ``raw_buffer`` - default, used when no transport protocol is detected,
+  // * ``tls`` - set by :ref:`envoy.listener.tls_inspector <config_listener_filters_tls_inspector>`
+  //   when TLS protocol is detected.
+  string transport_protocol = 9;
 }
 
 // A filter chain wraps a set of match criteria, an option TLS context, a set of filters, and