quic: support for server-preferred address behind DNAT

api/envoy/extensions/quic/server_preferred_address/v3/BUILD

@@ -6,6 +6,7 @@ licenses(["notice"])  # Apache 2
 
 api_proto_package(
     deps = [
+        "//envoy/config/core/v3:pkg",
         "@com_github_cncf_xds//udpa/annotations:pkg",
         "@com_github_cncf_xds//xds/annotations/v3:pkg",
     ],

api/envoy/extensions/quic/server_preferred_address/v3/fixed_server_preferred_address_config.proto

@@ -2,6 +2,8 @@ syntax = "proto3";
 
 package envoy.extensions.quic.server_preferred_address.v3;
 
+import "envoy/config/core/v3/address.proto";
+
 import "xds/annotations/v3/status.proto";
 
 import "udpa/annotations/status.proto";
@@ -21,15 +23,41 @@ message FixedServerPreferredAddressConfig {
 
   option (xds.annotations.v3.message_status).work_in_progress = true;
 
-  oneof ipv4_type {
-    // String representation of IPv4 address, i.e. "127.0.0.2".
-    // If not specified, none will be configured.
-    string ipv4_address = 1;
+  // Addresses for server preferred address for a single address family (IPv4 or IPv6).
+  message AddressFamilyConfig {
+    // The server preferred address sent to clients.
+    //
+    // Note: Envoy currently must receive all packets for a QUIC connection on the same port, so unless
+    // :ref:`dnat_address <envoy_v3_api_field_extensions.quic.server_preferred_address.v3.FixedServerPreferredAddressConfig.AddressFamilyConfig.dnat_address>`
+    // is configured, the port for this address must be zero, and the listener's
+    // port will be used instead.
+    config.core.v3.SocketAddress address = 1;
+
+    // If there is a DNAT between the client and Envoy, the address that Envoy will observe
+    // server preferred address packets being sent to. If this is not specified, it is assumed
+    // there is no DNAT and the server preferred address packets will be sent to the address advertised
+    // to clients for server preferred address.
+    //
+    // Note: Envoy currently must receive all packets for a QUIC connection on the same port, so the
+    // port for this address must be zero, and the listener's port will be used instead.
+    config.core.v3.SocketAddress dnat_address = 2;
   }
 
-  oneof ipv6_type {
-    // String representation of IPv6 address, i.e. "::1".
-    // If not specified, none will be configured.
-    string ipv6_address = 2;
-  }
+  // String representation of IPv4 address, i.e. "127.0.0.2".
+  // If not specified, none will be configured.
+  string ipv4_address = 1;
+
+  // The IPv4 address to advertise to clients for Server Preferred Address.
+  // This field takes precedence over
+  // :ref:`ipv4_address <envoy_v3_api_field_extensions.quic.server_preferred_address.v3.FixedServerPreferredAddressConfig.ipv4_address>`.
+  AddressFamilyConfig ipv4_config = 3;
+
+  // String representation of IPv6 address, i.e. "::1".
+  // If not specified, none will be configured.
+  string ipv6_address = 2;
+
+  // The IPv6 address to advertise to clients for Server Preferred Address.
+  // This field takes precedence over
+  // :ref:`ipv6_address <envoy_v3_api_field_extensions.quic.server_preferred_address.v3.FixedServerPreferredAddressConfig.ipv6_address>`.
+  AddressFamilyConfig ipv6_config = 4;
 }

changelogs/current.yaml

@@ -62,6 +62,11 @@ new_features:
   change: |
     Added :ref:`Filter State Input <envoy_v3_api_msg_extensions.matching.common_inputs.network.v3.FilterStateInput>`
     for matching http input based on filter state objects.
+- area: quic
+  change: |
+    Added support for QUIC server preferred address when there is a DNAT between the client and Envoy. See
+    :ref:`new config
+    <envoy_v3_api_field_extensions.quic.server_preferred_address.v3.FixedServerPreferredAddressConfig.AddressFamilyConfig.dnat_address>`.
 - area: cares
   change: |
     Added :ref:`udp_max_queries<envoy_v3_api_field_extensions.network.dns_resolver.cares.v3.CaresDnsResolverConfig.udp_max_queries>`

source/common/quic/active_quic_listener.cc

@@ -343,22 +343,37 @@ Network::ConnectionHandler::ActiveUdpListenerPtr ActiveQuicListenerFactory::crea
     Network::ListenerConfig& config) {
   ASSERT(crypto_server_stream_factory_.has_value());
   if (server_preferred_address_config_ != nullptr) {
-    std::pair<quic::QuicSocketAddress, quic::QuicSocketAddress> addresses =
+    const EnvoyQuicServerPreferredAddressConfig::Addresses addresses =
         server_preferred_address_config_->getServerPreferredAddresses(
             listen_socket_ptr->connectionInfoProvider().localAddress());
-    quic::QuicSocketAddress v4_address = addresses.first;
-    if (v4_address.IsInitialized()) {
-      ENVOY_BUG(v4_address.host().address_family() == quiche::IpAddressFamily::IP_V4,
+    if (addresses.ipv4_.IsInitialized()) {
+      ENVOY_BUG(addresses.ipv4_.host().address_family() == quiche::IpAddressFamily::IP_V4,
                 absl::StrCat("Configured IPv4 server's preferred address isn't a v4 address:",
-                             v4_address.ToString()));
-      quic_config_.SetIPv4AlternateServerAddressToSend(v4_address);
+                             addresses.ipv4_.ToString()));
+      if (addresses.dnat_ipv4_.IsInitialized()) {
+        ENVOY_BUG(
+            addresses.dnat_ipv4_.host().address_family() == quiche::IpAddressFamily::IP_V4,
+            absl::StrCat("Configured IPv4 server's preferred DNAT address isn't a v4 address:",
+                         addresses.dnat_ipv4_.ToString()));
+        quic_config_.SetIPv4AlternateServerAddressForDNat(addresses.ipv4_, addresses.dnat_ipv4_);
+      } else {
+        quic_config_.SetIPv4AlternateServerAddressToSend(addresses.ipv4_);
+      }
     }
-    quic::QuicSocketAddress v6_address = addresses.second;
-    if (v6_address.IsInitialized()) {
-      ENVOY_BUG(v6_address.host().address_family() == quiche::IpAddressFamily::IP_V6,
+
+    if (addresses.ipv6_.IsInitialized()) {
+      ENVOY_BUG(addresses.ipv6_.host().address_family() == quiche::IpAddressFamily::IP_V6,
                 absl::StrCat("Configured IPv6 server's preferred address isn't a v6 address:",
-                             v4_address.ToString()));
-      quic_config_.SetIPv6AlternateServerAddressToSend(v6_address);
+                             addresses.ipv6_.ToString()));
+      if (addresses.dnat_ipv6_.IsInitialized()) {
+        ENVOY_BUG(
+            addresses.dnat_ipv6_.host().address_family() == quiche::IpAddressFamily::IP_V6,
+            absl::StrCat("Configured IPv6 server's preferred DNAT address isn't a v6 address:",
+                         addresses.dnat_ipv6_.ToString()));
+        quic_config_.SetIPv6AlternateServerAddressForDNat(addresses.ipv6_, addresses.dnat_ipv6_);
+      } else {
+        quic_config_.SetIPv6AlternateServerAddressToSend(addresses.ipv6_);
+      }
     }
   }
 

source/common/quic/envoy_quic_server_preferred_address_config_factory.h

@@ -15,14 +15,29 @@ class EnvoyQuicServerPreferredAddressConfig {
 public:
   virtual ~EnvoyQuicServerPreferredAddressConfig() = default;
 
+  // The set of addresses used to configure the server preferred addresses.
+  struct Addresses {
+    // Addresses that client is requested to use.
+    quic::QuicSocketAddress ipv4_;
+    quic::QuicSocketAddress ipv6_;
+
+    // If destination NAT is applied between the client and Envoy, the addresses that
+    // Envoy will see for client traffic to the server preferred address. If this is not
+    // set, Envoy will expect to receive server preferred address traffic on the above addresses.
+    //
+    // A DNAT address will be ignored if the corresponding SPA address is not set.
+    quic::QuicSocketAddress dnat_ipv4_;
+    quic::QuicSocketAddress dnat_ipv6_;
+  };
+
   /**
    * Called during config loading.
    * @param local_address the configured default listening address.
    * Returns a pair of the server preferred addresses in form of {IPv4, IPv6} which will be used for
    * the entire life time of the QUIC listener. An uninitialized address value means no preferred
    * address for that address family.
    */
-  virtual std::pair<quic::QuicSocketAddress, quic::QuicSocketAddress>
+  virtual Addresses
   getServerPreferredAddresses(const Network::Address::InstanceConstSharedPtr& local_address) PURE;
 };
 

source/extensions/quic/server_preferred_address/BUILD

@@ -23,6 +23,7 @@ envoy_cc_library(
     deps = [
         "//envoy/registry",
         "//source/common/quic:envoy_quic_server_preferred_address_config_factory_interface",
+        "//source/common/quic:envoy_quic_utils_lib",
         "@envoy_api//envoy/extensions/quic/server_preferred_address/v3:pkg_cc_proto",
     ],
     alwayslink = LEGACY_ALWAYSLINK,

source/extensions/quic/server_preferred_address/fixed_server_preferred_address_config.cc

@@ -1,13 +1,118 @@
 #include "source/extensions/quic/server_preferred_address/fixed_server_preferred_address_config.h"
 
+#include "source/common/network/utility.h"
+#include "source/common/quic/envoy_quic_utils.h"
+
 namespace Envoy {
 namespace Quic {
 
-std::pair<quic::QuicSocketAddress, quic::QuicSocketAddress>
+namespace {
+
+quic::QuicSocketAddress ipOrAddressToAddress(const quic::QuicSocketAddress& address, int32_t port) {
+  if (address.port() == 0) {
+    return quic::QuicSocketAddress(address.host(), port);
+  }
+
+  return address;
+}
+
+quic::QuicIpAddress parseIp(const std::string& addr, absl::string_view address_family,
+                            const Protobuf::Message& message) {
+  quic::QuicIpAddress ip;
+  if (!ip.FromString(addr)) {
+    ProtoExceptionUtil::throwProtoValidationException(
+        absl::StrCat("bad ", address_family, " server preferred address: ", addr), message);
+  }
+  return ip;
+}
+
+quic::QuicSocketAddress parseSocketAddress(const envoy::config::core::v3::SocketAddress& addr,
+                                           Network::Address::IpVersion version,
+                                           absl::string_view version_str,
+                                           const Protobuf::Message& message) {
+  // There's no utility to convert from a `SocketAddress`, so wrap it in an `Address` to make use of
+  // existing helpers.
+  envoy::config::core::v3::Address outer;
+  *outer.mutable_socket_address() = addr;
+  auto envoy_addr = Network::Utility::protobufAddressToAddress(outer);
+  ASSERT(envoy_addr != nullptr,
+         "Network::Utility::protobufAddressToAddress throws on failure so this can't be nullptr");
+  if (envoy_addr->ip() == nullptr || envoy_addr->ip()->version() != version) {
+    ProtoExceptionUtil::throwProtoValidationException(
+        absl::StrCat("wrong address type for ", version_str, " server preferred address: ", addr),
+        message);
+  }
+
+  return envoyIpAddressToQuicSocketAddress(envoy_addr->ip());
+}
+
+quic::QuicIpAddress
+parseIpAddressFromSocketAddress(const envoy::config::core::v3::SocketAddress& addr,
+                                Network::Address::IpVersion version, absl::string_view version_str,
+                                const Protobuf::Message& message) {
+  auto socket_addr = parseSocketAddress(addr, version, version_str, message);
+  if (socket_addr.port() != 0) {
+    ProtoExceptionUtil::throwProtoValidationException(
+        fmt::format("port must be 0 in this version of Envoy in address '{}'",
+                    socket_addr.ToString()),
+        message);
+  }
+
+  return socket_addr.host();
+}
+
+FixedServerPreferredAddressConfig::FamilyAddresses
+parseFamily(const std::string& addr_string,
+            const envoy::extensions::quic::server_preferred_address::v3::
+                FixedServerPreferredAddressConfig::AddressFamilyConfig* addresses,
+            Network::Address::IpVersion version, absl::string_view address_family,
+            const Protobuf::Message& message) {
+  FixedServerPreferredAddressConfig::FamilyAddresses ret;
+  if (addresses != nullptr) {
+    if (addresses->has_dnat_address() && !addresses->has_address()) {
+      ProtoExceptionUtil::throwProtoValidationException(
+          absl::StrCat("'dnat_address' but not 'address' is set in server preferred address for ",
+                       address_family),
+          message);
+    }
+
+    if (addresses->has_address()) {
+      ret.spa_ = parseSocketAddress(addresses->address(), version, address_family, message);
+
+      if (!addresses->has_dnat_address() && ret.spa_.port() != 0) {
+        ProtoExceptionUtil::throwProtoValidationException(
+            fmt::format("'address' port must be zero unless 'dnat_address' is set in address {} "
+                        "for address family {}",
+                        ret.spa_.ToString(), address_family),
+            message);
+      }
+    }
+
+    if (addresses->has_dnat_address()) {
+      ret.dnat_ = parseIpAddressFromSocketAddress(addresses->dnat_address(), version,
+                                                  address_family, message);
+    }
+  } else {
+    if (!addr_string.empty()) {
+      ret.spa_ = quic::QuicSocketAddress(parseIp(addr_string, address_family, message), 0);
+    }
+  }
+
+  return ret;
+}
+
+} // namespace
+
+EnvoyQuicServerPreferredAddressConfig::Addresses
 FixedServerPreferredAddressConfig::getServerPreferredAddresses(
     const Network::Address::InstanceConstSharedPtr& local_address) {
   int32_t port = local_address->ip()->port();
-  return {quic::QuicSocketAddress(ip_v4_, port), quic::QuicSocketAddress(ip_v6_, port)};
+  Addresses addresses;
+  addresses.ipv4_ = ipOrAddressToAddress(v4_.spa_, port);
+  addresses.ipv6_ = ipOrAddressToAddress(v6_.spa_, port);
+  addresses.dnat_ipv4_ = quic::QuicSocketAddress(v4_.dnat_, port);
+  addresses.dnat_ipv6_ = quic::QuicSocketAddress(v6_.dnat_, port);
+  return addresses;
 }
 
 Quic::EnvoyQuicServerPreferredAddressConfigPtr
@@ -18,20 +123,15 @@ FixedServerPreferredAddressConfigFactory::createServerPreferredAddressConfig(
       MessageUtil::downcastAndValidate<const envoy::extensions::quic::server_preferred_address::v3::
                                            FixedServerPreferredAddressConfig&>(message,
                                                                                validation_visitor);
-  quic::QuicIpAddress ip_v4, ip_v6;
-  if (config.has_ipv4_address()) {
-    if (!ip_v4.FromString(config.ipv4_address())) {
-      ProtoExceptionUtil::throwProtoValidationException(
-          absl::StrCat("bad v4 server preferred address: ", config.ipv4_address()), message);
-    }
-  }
-  if (config.has_ipv6_address()) {
-    if (!ip_v6.FromString(config.ipv6_address())) {
-      ProtoExceptionUtil::throwProtoValidationException(
-          absl::StrCat("bad v6 server preferred address: ", config.ipv6_address()), message);
-    }
-  }
-  return std::make_unique<FixedServerPreferredAddressConfig>(ip_v4, ip_v6);
+
+  FixedServerPreferredAddressConfig::FamilyAddresses v4 =
+      parseFamily(config.ipv4_address(), config.has_ipv4_config() ? &config.ipv4_config() : nullptr,
+                  Network::Address::IpVersion::v4, "v4", message);
+  FixedServerPreferredAddressConfig::FamilyAddresses v6 =
+      parseFamily(config.ipv6_address(), config.has_ipv6_config() ? &config.ipv6_config() : nullptr,
+                  Network::Address::IpVersion::v6, "v6", message);
+
+  return std::make_unique<FixedServerPreferredAddressConfig>(v4, v6);
 }
 
 REGISTER_FACTORY(FixedServerPreferredAddressConfigFactory,

source/extensions/quic/server_preferred_address/fixed_server_preferred_address_config.h

@@ -11,16 +11,20 @@ namespace Quic {
 
 class FixedServerPreferredAddressConfig : public Quic::EnvoyQuicServerPreferredAddressConfig {
 public:
-  FixedServerPreferredAddressConfig(const quic::QuicIpAddress& ipv4,
-                                    const quic::QuicIpAddress& ipv6)
-      : ip_v4_(ipv4), ip_v6_(ipv6) {}
+  struct FamilyAddresses {
+    quic::QuicSocketAddress spa_;
+    quic::QuicIpAddress dnat_;
+  };
 
-  std::pair<quic::QuicSocketAddress, quic::QuicSocketAddress> getServerPreferredAddresses(
+  FixedServerPreferredAddressConfig(const FamilyAddresses& v4, const FamilyAddresses& v6)
+      : v4_(v4), v6_(v6) {}
+
+  Addresses getServerPreferredAddresses(
       const Network::Address::InstanceConstSharedPtr& local_address) override;
 
 private:
-  const quic::QuicIpAddress ip_v4_;
-  const quic::QuicIpAddress ip_v6_;
+  const FamilyAddresses v4_;
+  const FamilyAddresses v6_;
 };
 
 class FixedServerPreferredAddressConfigFactory

test/extensions/quic/server_preferred_address/BUILD

@@ -0,0 +1,23 @@
+load(
+    "//bazel:envoy_build_system.bzl",
+    "envoy_package",
+)
+load(
+    "//test/extensions:extensions_build_system.bzl",
+    "envoy_extension_cc_test",
+)
+
+licenses(["notice"])  # Apache 2
+
+envoy_package()
+
+envoy_extension_cc_test(
+    name = "fixed_server_preferred_address_test",
+    srcs = ["fixed_server_preferred_address_test.cc"],
+    extension_names = ["envoy.quic.server_preferred_address.fixed"],
+    tags = ["nofips"],
+    deps = [
+        "//source/extensions/quic/server_preferred_address:fixed_server_preferred_address_config_lib",
+        "//test/mocks/protobuf:protobuf_mocks",
+    ],
+)