grpc-xds: add virtual-host domain matching (#2871)

## Motivation

Ref: #2754 

For gRFC A74 XdsDependencyManager, to resolve the channel's virtual
host, we'll need to run string matching per Envoy `StringMatcher` spec.

## Solution

To reduce the size of the upcoming A74 PR, I'm sending this
`StringMatcher` PR first. The implementation mostly follows the design
we used in `tonic-xds`, with these highlights:

1. Since the same string matching logic is shared between the virtual
host selection and A29 SAN matching for mTLS, we extracted a common
`StringMatcher` validated resource type and a pure `matcher` module.
2. Used the Rust idiomatic "new type" pattern for `DomainMatchScore` and
`SafeRegex`: the former encapsulate the match ordering semantics, and
the latter to reject empty regex pattern and conform to the "only match
the entire input" Envoy spec.

Author: YutaoMa

grpc-xds/build.rs

@@ -37,7 +37,8 @@
 //! instead of colliding.
 
 use std::collections::BTreeMap;
-use std::path::{Path, PathBuf};
+use std::path::Path;
+use std::path::PathBuf;
 
 fn main() {
     let manifest = PathBuf::from(std::env::var("CARGO_MANIFEST_DIR").unwrap());

grpc-xds/rustfmt.toml

@@ -0,0 +1 @@
+imports_granularity = "Item"

grpc-xds/src/lib.rs

@@ -38,23 +38,26 @@
     unused,
     clippy::all
 )]
-pub(crate) mod generated {
+mod generated {
     include!(concat!(env!("OUT_DIR"), "/generated/mod.rs"));
 }
 
 /// Validated xDS resource types (LDS/RDS/CDS/EDS), each implementing
 /// `xds_client::Resource` so they can be deserialized, named, and validated
 /// per their respective gRFCs (A27 core resource types, A28 route matching,
 /// A37 aggregate clusters).
-pub(crate) mod resource;
+mod resource;
+
+/// Pure routing utilities.
+mod routing;
 
 /// xDS load balancing policies (gRFC A31 and friends), plus
 /// [`load_balancing::register`] to install them in the gRPC LB registry.
 mod load_balancing;
 
 /// [`xds_config::XdsConfig`]: the atomic xDS configuration snapshot assembled
 /// from a channel's Listener/RouteConfiguration/Cluster/Endpoints resources.
-pub(crate) mod xds_config;
+mod xds_config;
 
 #[cfg(test)]
 mod tests {
@@ -66,10 +69,10 @@ mod tests {
     //! `generated` module is `pub(crate)` — doctests compile as an external
     //! crate and can only reach the public API.
 
-    use crate::generated::envoy::config::{
-        cluster::v3::Cluster, endpoint::v3::ClusterLoadAssignment, listener::v3::Listener,
-        route::v3::RouteConfiguration,
-    };
+    use crate::generated::envoy::config::cluster::v3::Cluster;
+    use crate::generated::envoy::config::endpoint::v3::ClusterLoadAssignment;
+    use crate::generated::envoy::config::listener::v3::Listener;
+    use crate::generated::envoy::config::route::v3::RouteConfiguration;
 
     /// Encodes then decodes a message. `serialize` / `parse` are methods of the
     /// `protobuf::Message` trait (in scope via the `M: protobuf::Message` bound).

grpc-xds/src/resource/cluster.rs

@@ -25,11 +25,13 @@
 //! Validated Cluster resource (CDS).
 
 use protobuf::Parse;
+use xds_client::Error;
+use xds_client::Resource;
 use xds_client::resource::TypeUrl;
-use xds_client::{Error, Resource};
 
+use crate::generated::envoy::config::cluster::v3::Cluster;
+use crate::generated::envoy::config::cluster::v3::cluster::ClusterDiscoveryTypeOneof;
 use crate::generated::envoy::config::cluster::v3::cluster::DiscoveryType;
-use crate::generated::envoy::config::cluster::v3::{Cluster, cluster::ClusterDiscoveryTypeOneof};
 use crate::generated::envoy::extensions::clusters::aggregate::v3::ClusterConfig as AggregateClusterConfig;
 
 /// Extension name and `typed_config` type for gRFC A37 aggregate clusters.
@@ -262,15 +264,16 @@ fn validate_aggregate_discovery(
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::generated::envoy::config::cluster::v3::cluster::{
-        CustomClusterType, EdsClusterConfig,
-    };
-    use crate::generated::envoy::config::core::v3::{
-        Address, AggregatedConfigSource, ConfigSource, SocketAddress,
-    };
-    use crate::generated::envoy::config::endpoint::v3::{
-        ClusterLoadAssignment, Endpoint, LbEndpoint, LocalityLbEndpoints,
-    };
+    use crate::generated::envoy::config::cluster::v3::cluster::CustomClusterType;
+    use crate::generated::envoy::config::cluster::v3::cluster::EdsClusterConfig;
+    use crate::generated::envoy::config::core::v3::Address;
+    use crate::generated::envoy::config::core::v3::AggregatedConfigSource;
+    use crate::generated::envoy::config::core::v3::ConfigSource;
+    use crate::generated::envoy::config::core::v3::SocketAddress;
+    use crate::generated::envoy::config::endpoint::v3::ClusterLoadAssignment;
+    use crate::generated::envoy::config::endpoint::v3::Endpoint;
+    use crate::generated::envoy::config::endpoint::v3::LbEndpoint;
+    use crate::generated::envoy::config::endpoint::v3::LocalityLbEndpoints;
     use protobuf::Serialize;
     use protobuf_well_known_types::Any;
 

grpc-xds/src/resource/endpoint.rs

@@ -24,16 +24,17 @@
 
 //! Validated ClusterLoadAssignment resource (EDS).
 
-use std::collections::{HashMap, HashSet};
+use std::collections::HashMap;
+use std::collections::HashSet;
 
 use protobuf::Parse;
+use xds_client::Error;
+use xds_client::Resource;
 use xds_client::resource::TypeUrl;
-use xds_client::{Error, Resource};
 
 use crate::generated::envoy::config::core::v3::HealthStatus as EnvoyHealthStatus;
-use crate::generated::envoy::config::endpoint::v3::{
-    ClusterLoadAssignment, lb_endpoint::HostIdentifierOneof,
-};
+use crate::generated::envoy::config::endpoint::v3::ClusterLoadAssignment;
+use crate::generated::envoy::config::endpoint::v3::lb_endpoint::HostIdentifierOneof;
 
 /// Validated ClusterLoadAssignment (EDS resource).
 #[derive(Debug, Clone)]
@@ -315,12 +316,12 @@ impl EndpointsResource {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::generated::envoy::config::core::v3::{
-        Address, Locality as EnvoyLocality, SocketAddress,
-    };
-    use crate::generated::envoy::config::endpoint::v3::{
-        Endpoint, LbEndpoint as EnvoyLbEndpoint, LocalityLbEndpoints as EnvoyLocalityLbEndpoints,
-    };
+    use crate::generated::envoy::config::core::v3::Address;
+    use crate::generated::envoy::config::core::v3::Locality as EnvoyLocality;
+    use crate::generated::envoy::config::core::v3::SocketAddress;
+    use crate::generated::envoy::config::endpoint::v3::Endpoint;
+    use crate::generated::envoy::config::endpoint::v3::LbEndpoint as EnvoyLbEndpoint;
+    use crate::generated::envoy::config::endpoint::v3::LocalityLbEndpoints as EnvoyLocalityLbEndpoints;
     use protobuf::Serialize;
     use protobuf_well_known_types::UInt32Value;
 

grpc-xds/src/resource/listener.rs

@@ -28,8 +28,9 @@ use std::sync::Arc;
 
 use protobuf::Parse;
 use protobuf_well_known_types::Any;
+use xds_client::Error;
+use xds_client::Resource;
 use xds_client::resource::TypeUrl;
-use xds_client::{Error, Resource};
 
 use super::route::RouteConfigResource;
 use crate::generated::envoy::config::listener::v3::Listener;
@@ -161,13 +162,15 @@ impl ListenerResource {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::generated::envoy::config::core::v3::{
-        AggregatedConfigSource, ConfigSource, SelfConfigSource,
-    };
+    use crate::generated::envoy::config::core::v3::AggregatedConfigSource;
+    use crate::generated::envoy::config::core::v3::ConfigSource;
+    use crate::generated::envoy::config::core::v3::SelfConfigSource;
     use crate::generated::envoy::config::listener::v3::ApiListener;
-    use crate::generated::envoy::config::route::v3::{
-        Route, RouteAction, RouteConfiguration, RouteMatch, VirtualHost,
-    };
+    use crate::generated::envoy::config::route::v3::Route;
+    use crate::generated::envoy::config::route::v3::RouteAction;
+    use crate::generated::envoy::config::route::v3::RouteConfiguration;
+    use crate::generated::envoy::config::route::v3::RouteMatch;
+    use crate::generated::envoy::config::route::v3::VirtualHost;
     use crate::generated::envoy::extensions::filters::network::http_connection_manager::v3::Rds;
     use protobuf::Serialize;
 

grpc-xds/src/resource/mod.rs

@@ -36,13 +36,28 @@ mod cluster;
 mod endpoint;
 mod listener;
 mod route;
+mod safe_regex;
+mod string_matcher;
 
-pub(crate) use cluster::{ClusterDiscovery, ClusterResource};
-pub(crate) use endpoint::{
-    EndpointAddress, EndpointsResource, HealthStatus, LbEndpoint, Locality, LocalityLbEndpoints,
-};
-pub(crate) use listener::{ListenerResource, RouteSource};
-pub(crate) use route::{
-    HeaderMatchSpecifier, HeaderMatcher, PathSpecifier, Route, RouteAction, RouteConfigResource,
-    RouteMatch, StringMatcher, VirtualHost, WeightedCluster,
-};
+pub(crate) use cluster::ClusterDiscovery;
+pub(crate) use cluster::ClusterResource;
+pub(crate) use endpoint::EndpointAddress;
+pub(crate) use endpoint::EndpointsResource;
+pub(crate) use endpoint::HealthStatus;
+pub(crate) use endpoint::LbEndpoint;
+pub(crate) use endpoint::Locality;
+pub(crate) use endpoint::LocalityLbEndpoints;
+pub(crate) use listener::ListenerResource;
+pub(crate) use listener::RouteSource;
+pub(crate) use route::DomainMatcher;
+pub(crate) use route::HeaderMatchSpecifier;
+pub(crate) use route::HeaderMatcher;
+pub(crate) use route::PathSpecifier;
+pub(crate) use route::Route;
+pub(crate) use route::RouteAction;
+pub(crate) use route::RouteConfigResource;
+pub(crate) use route::RouteMatch;
+pub(crate) use route::VirtualHost;
+pub(crate) use route::WeightedCluster;
+pub(crate) use safe_regex::SafeRegex;
+pub(crate) use string_matcher::StringMatcher;