grpc/client: HTTP CONNECT proxy support in transport#2698
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This reverts commit 0428123.
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…ration (#2679) This PR implements a resolver wrapper that determines proxy routing by checking the `HTTPS_PROXY` and `NO_PROXY` environment variables. By default, `hyper-util` matches cURL's behavior by falling back to `ALL_PROXY` when `HTTPS_PROXY` is unset. However, because Go's [`FromEnvironment`](https://pkg.go.dev/golang.org/x/net/http/httpproxy#FromEnvironment) and gRPC C++ ignore `ALL_PROXY`, gRPC Rust manually configures the `Matcher` to bypass it, ensuring cross-language consistency. **Resolution Flow** When `HttpsProxyResolver::Builder` builds a resolver for a target URI, it uses `hyper_util::client::proxy::Matcher` to evaluate the environment variables: 1. **Direct Connection:** If no proxy is required, it delegates resolution entirely to the wrapped child builder, bypassing the proxy resolver. 2. **Proxied Connection:** If a proxy is required, it creates an `HttpsProxyResolver`, which uses the child DNS resolver to resolve the *proxy server's* hostname instead of the target. 3. **Attribute Injection:** The `HttpsProxyResolver` intercepts resolution updates from the child resolver. It attaches the necessary proxy configuration (the original target authority and basic auth credentials) as attributes to each resolved proxy address. In follow-up PRs, the subchannel will read these address attributes to wrap the channel credentials and carry out the HTTP `CONNECT` handshake prior to the standard credential handshake. Internal design doc: [go/grpc-rust-http-connect](http://go/grpc-rust-http-connect) Transport changes: #2698
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I still need to look at the tests, but here's a first round of comments (all pretty minor I think).
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| let certs_path = PathBuf::from(env!("CARGO_MANIFEST_DIR")) | ||
| .parent() | ||
| .unwrap() | ||
| .join("examples/data/tls"); | ||
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| let server_cert = fs::read(certs_path.join("server.pem")).expect("failed to read server.pem"); | ||
| let server_key = fs::read(certs_path.join("server.key")).expect("failed to read server.key"); | ||
| let ca_cert = fs::read(certs_path.join("ca.pem")).expect("failed to read ca.pem"); | ||
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| let identity = Identity::from_pem(server_cert, server_key); | ||
| let identity_provider = StaticProvider::new(vec![identity]); | ||
| let server_tls_config = ServerTlsConfig::new(identity_provider); | ||
| let server_creds = RustlsServerCredendials::new(server_tls_config).unwrap(); | ||
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| let server_listener = TcpListener::bind("127.0.0.1:0").await.unwrap(); | ||
| let server_addr = server_listener.local_addr().unwrap(); |
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Maybe we can make some helpers to avoid some of the duplication here? Even if it's broken up into a few smaller and reusable parts, like one function that creates the credentials, that could be helpful.
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Created helper functions to construct client/server credentials, perform the CONNECT handshake, and initialize the server.
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This PR introduces an
HttpConnectHandshakerthat wraps theChannelCredentialsto complete the HTTP CONNECT handshake based on theAddressattributes introduced in #2679. This allows the subchannel to configure proxying transparently without requiring changes to the Transport API.