Convert WebSocket URLRequest to RFC8441 HTTPRequest (#92)

WebSocket uses the extended-CONNECT form in HTTP/2 and HTTP/3. When
creating an HTTPRequest from a URLRequest, we should translate it into
the new form.

`:method`: `GET` -> `CONNECT`
`:scheme`: `wss`/`ws` -> `https`/`http`
`:protocol`: `websocket`

HTTPTypes defaults to modern HTTP versions, and the expectation is that
the HTTP/1 serializer has to translate the extended-CONNECT request back
to the old request form.

---------

Co-authored-by: Cory Benfield <[email protected]>

Author: guoye-zhang

Sources/HTTPTypesFoundation/URLRequest+HTTPTypes.swift

@@ -25,6 +25,23 @@ extension URLRequest {
     /// Create a `URLRequest` from an `HTTPRequest`.
     /// - Parameter httpRequest: The HTTP request to convert from.
     public init?(httpRequest: HTTPRequest) {
+        // Translate an extended-CONNECT WebSocket request to the legacy form
+        if httpRequest.method == .connect && httpRequest.extendedConnectProtocol == "websocket" {
+            var legacyRequest = httpRequest
+            legacyRequest.method = .get
+            switch httpRequest.scheme?.lowercased() {
+            case "https":
+                legacyRequest.scheme = "wss"
+            case "http":
+                legacyRequest.scheme = "ws"
+            default:
+                break
+            }
+            legacyRequest.extendedConnectProtocol = nil
+            self.init(httpRequest: legacyRequest)
+            return
+        }
+
         guard let url = httpRequest.url else {
             return nil
         }
@@ -63,6 +80,27 @@ extension URLRequest {
                 }
             }
         }
+
+        // Translate a legacy WebSocket request to the extended-CONNECT form
+        if method == .get, let scheme = request.scheme {
+            switch scheme.utf8.count {
+            case 3:
+                if scheme.lowercased() == "wss" {
+                    request.method = .connect
+                    request.scheme = "https"
+                    request.extendedConnectProtocol = "websocket"
+                }
+            case 2:
+                if scheme.lowercased() == "ws" {
+                    request.method = .connect
+                    request.scheme = "http"
+                    request.extendedConnectProtocol = "websocket"
+                }
+            default:
+                break
+            }
+        }
+
         return request
     }
 }

Tests/HTTPTypesFoundationTests/HTTPTypesFoundationTests.swift

@@ -143,6 +143,22 @@ final class HTTPTypesFoundationTests: XCTestCase {
         XCTAssertEqual(request.headerFields[.init("x-foo")!], "Bar")
     }
 
+    func testWebSocketRequest() throws {
+        let urlRequest = URLRequest(url: URL(string: "wss://www.example.com/")!)
+
+        let request = try XCTUnwrap(urlRequest.httpRequest)
+        XCTAssertEqual(request.method, .connect)
+        XCTAssertEqual(request.scheme, "https")
+        XCTAssertEqual(request.authority, "www.example.com")
+        XCTAssertEqual(request.path, "/")
+        XCTAssertEqual(request.extendedConnectProtocol, "websocket")
+
+        let urlRequestConverted = try XCTUnwrap(URLRequest(httpRequest: request))
+        XCTAssertEqual(urlRequestConverted.httpMethod, "GET")
+        XCTAssertEqual(urlRequestConverted.url, URL(string: "wss://www.example.com/"))
+        XCTAssertEqual(urlRequest, urlRequestConverted)
+    }
+
     func testResponseToFoundation() throws {
         let response = HTTPResponse(
             status: .ok,