Ignore early hints for 4.9.x (#7444)

Author: yschimke

okhttp/src/jvmMain/kotlin/okhttp3/internal/http/CallServerInterceptor.kt

@@ -18,7 +18,9 @@ package okhttp3.internal.http
 import java.io.IOException
 import java.net.ProtocolException
 import okhttp3.Interceptor
+import okhttp3.Protocol
 import okhttp3.Response
+import okhttp3.internal.connection.Exchange
 import okhttp3.internal.http2.ConnectionShutdownException
 import okhttp3.internal.stripBody
 import okio.buffer
@@ -103,9 +105,8 @@ class CallServerInterceptor(private val forWebSocket: Boolean) : Interceptor {
           .receivedResponseAtMillis(System.currentTimeMillis())
           .build()
       var code = response.code
-      if (code == 100) {
-        // Server sent a 100-continue even though we did not request one. Try again to read the
-        // actual response status.
+
+      if (shouldIgnoreAndWaitForRealResponse(code, exchange)) {
         responseBuilder = exchange.readResponseHeaders(expectContinue = false)!!
         if (invokeStartEvent) {
           exchange.responseHeadersStart()
@@ -146,4 +147,15 @@ class CallServerInterceptor(private val forWebSocket: Boolean) : Interceptor {
       throw e
     }
   }
+
+  private fun shouldIgnoreAndWaitForRealResponse(code: Int, exchange: Exchange): Boolean = when {
+    // Server sent a 100-continue even though we did not request one. Try again to read the
+    // actual response status.
+    code == 100 -> true
+
+    // Early Hints (103) but not supported yet in OkHttp
+    code == 103 -> true
+
+    else -> false
+  }
 }

okhttp/src/jvmMain/kotlin/okhttp3/internal/http1/Http1ExchangeCodec.kt

@@ -34,6 +34,7 @@ import okhttp3.internal.http.StatusLine
 import okhttp3.internal.http.promisesBody
 import okhttp3.internal.http.receiveHeaders
 import okhttp3.internal.http.HTTP_CONTINUE
+import okhttp3.internal.http.HTTP_EARLY_HINTS
 import okhttp3.internal.skipAll
 import okio.Buffer
 import okio.BufferedSink
@@ -192,6 +193,11 @@ class Http1ExchangeCodec(
           state = STATE_READ_RESPONSE_HEADERS
           responseBuilder
         }
+        statusLine.code == HTTP_EARLY_HINTS -> {
+          // Early Hints will mean a second header are coming.
+          state = STATE_READ_RESPONSE_HEADERS
+          responseBuilder
+        }
         else -> {
           state = STATE_OPEN_RESPONSE_BODY
           responseBuilder

okhttp/src/jvmTest/java/okhttp3/CallTest.kt

@@ -2744,6 +2744,34 @@ open class CallTest {
     assertThat(recordedRequest.body.readUtf8()).isEqualTo("abc")
   }
 
+  @Test fun serverRespondsWithEarlyHintsHttp2() {
+    enableProtocol(Protocol.HTTP_2)
+    serverRespondsWithEarlyHints()
+  }
+
+  @Test fun serverRespondsWithEarlyHints() {
+    val mockResponse = MockResponse()
+    server.enqueue(
+   mockResponse.apply {
+     addInformationalResponse(
+       MockResponse()
+         .setResponseCode(103)
+         .setHeaders(headersOf("Link", "</style.css>; rel=preload; as=style"))
+     )
+   }
+ )
+    val request = Request(
+      url = server.url("/"),
+      body = "abc".toRequestBody("text/plain".toMediaType()),
+    )
+    executeSynchronously(request)
+      .assertCode(200)
+      .assertSuccessful()
+    val recordedRequest = server.takeRequest()
+    assertThat(recordedRequest.body.readUtf8()).isEqualTo("abc")
+    assertThat(recordedRequest.headers["Link"]).isNull()
+  }
+
   @Test fun serverRespondsWithUnsolicited100Continue_HTTP2() {
     enableProtocol(Protocol.HTTP_2)
     serverRespondsWithUnsolicited100Continue()