[4.x] Backport 1XX handling from master

okhttp-testing-support/src/main/kotlin/okhttp3/OkHttpClientTestRule.kt

@@ -264,6 +264,12 @@ class OkHttpClientTestRule : TestRule {
     }
   }
 
+  fun eventsList(): List<String> {
+    return synchronized(clientEventsList) {
+      clientEventsList.toList()
+    }
+  }
+
   companion object {
     /**
      * A network that resolves only one IP address per host. Use this when testing route selection

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

@@ -103,9 +103,8 @@ 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)) {
         responseBuilder = exchange.readResponseHeaders(expectContinue = false)!!
         if (invokeStartEvent) {
           exchange.responseHeadersStart()
@@ -148,4 +147,17 @@ class CallServerInterceptor(private val forWebSocket: Boolean) : Interceptor {
       throw e
     }
   }
+
+  private fun shouldIgnoreAndWaitForRealResponse(code: Int): 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
+
+    // Handle Processing (102) & Early Hints (103) and any new codes without failing
+    // 100 and 101 are the exceptions with different meanings
+    // But Early Hints not currently exposed
+    code in (102 until 200) -> true
+
+    else -> false
+  }
 }

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

@@ -193,6 +193,12 @@ class Http1ExchangeCodec(
           state = STATE_READ_RESPONSE_HEADERS
           responseBuilder
         }
+        statusLine.code in (102 until 200) -> {
+          // Processing and Early Hints will mean a second headers are coming.
+          // Treat others the same for now
+          state = STATE_READ_RESPONSE_HEADERS
+          responseBuilder
+        }
         else -> {
           state = STATE_OPEN_RESPONSE_BODY
           responseBuilder

okhttp/src/test/java/okhttp3/CacheTest.java

@@ -104,7 +104,10 @@ public final class CacheTest {
     // We can't test 100 because it's not really a response.
     // assertCached(false, 100);
     assertCached(false, 101);
-    assertCached(false, 102);
+    // We don't test 102 or 103 because it will break on the informational response with
+    // mockwebserver.
+//    assertSubsequentResponseCached( 102, 200);
+//    assertSubsequentResponseCached( 103, 200);
     assertCached(true, 200);
     assertCached(false, 201);
     assertCached(false, 202);
@@ -151,7 +154,7 @@ public final class CacheTest {
     assertCached(false, 506);
   }
 
-  private void assertCached(boolean shouldPut, int responseCode) throws Exception {
+  private void assertCached(boolean shouldWriteToCache, int responseCode) throws Exception {
     int expectedResponseCode = responseCode;
 
     server = new MockWebServer();
@@ -193,7 +196,7 @@ private void assertCached(boolean shouldPut, int responseCode) throws Exception
     response.body().string();
 
     Response cached = cacheGet(cache, request);
-    if (shouldPut) {
+    if (shouldWriteToCache) {
       assertThat(cached).isNotNull();
       cached.body().close();
     } else {

okhttp/src/test/java/okhttp3/InformationalResponseCodeTest.kt

@@ -0,0 +1,56 @@
+/*
+ * Copyright (C) 2023 Block, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package okhttp3
+
+import okhttp3.testing.PlatformRule
+import org.assertj.core.api.Assertions.assertThat
+import org.junit.Ignore
+import org.junit.Rule
+import org.junit.Test
+
+@Ignore("For manual testing only")
+class InformationalResponseCodeTest {
+  @JvmField @Rule
+  val platform = PlatformRule()
+
+  @JvmField @Rule val clientTestRule = OkHttpClientTestRule().apply {
+    recordFrames = true
+  }
+
+  private var client = clientTestRule.newClient()
+
+  @Test
+  fun test103() {
+    // Pretend we are curl so cloudflare will send a 103
+    val request = Request.Builder()
+      .url("https://tradingstrategy.ai")
+      .header("user-agent", "curl/7.85.0")
+      .build()
+
+    val response = client.newCall(request).execute()
+
+    assertThat(response.code).isEqualTo(200)
+    assertThat(response.protocol).isEqualTo(Protocol.HTTP_2)
+    response.close()
+
+    val outgoingHeaders = ">> 0x00000003\\s+\\d+\\s+HEADERS\\s+END_STREAM\\|END_HEADERS".toRegex()
+    assertThat(clientTestRule.eventsList().filter { it.matches(outgoingHeaders) }).hasSize(1)
+
+    // Confirm we get the informational response and final response headers.
+    val incomingHeaders = "<< 0x00000003\\s+\\d+\\s+HEADERS\\s+END_HEADERS".toRegex()
+    assertThat(clientTestRule.eventsList().filter { it.matches(incomingHeaders) }).hasSize(2)
+  }
+}