Don't crash reading non-ASCII characters from the server or the cache.

This doesn't completely support ISO-8859-1 headers; instead they will most likely
be mangled when they are decoded as UTF-8. If we decide we absolutely must support
ISO-8859-1 here we can do that in another change. (I'm not currently enthusiastic
about this idea.)

But this does prevent OkHttp from crashing when it encounters non-ASCII characters
in headers for HTTP/2, SPDY, and cached responses.

Closes: #1998

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

@@ -2320,6 +2320,31 @@ public void assertCookies(HttpUrl url, String... expectedCookies) throws Excepti
     assertEquals("v2", server.takeRequest().getHeader("If-None-Match"));
   }
 
+  @Test public void combinedCacheHeadersCanBeNonAscii() throws Exception {
+    server.enqueue(new MockResponse()
+        .addHeader("Last-Modified: " + formatDate(-1, TimeUnit.HOURS))
+        .addHeader("Cache-Control: max-age=0")
+        .addHeaderLenient("Alpha", "α")
+        .addHeaderLenient("β", "Beta")
+        .setBody("abcd"));
+    server.enqueue(new MockResponse()
+        .addHeader("Transfer-Encoding: none")
+        .addHeaderLenient("Gamma", "Γ")
+        .addHeaderLenient("Δ", "Delta")
+        .setResponseCode(HttpURLConnection.HTTP_NOT_MODIFIED));
+
+    Response response1 = get(server.url("/"));
+    assertEquals("α", response1.header("Alpha"));
+    assertEquals("Beta", response1.header("β"));
+    assertEquals("abcd", response1.body().string());
+
+    Response response2 = get(server.url("/"));
+    assertEquals("α", response2.header("Alpha"));
+    assertEquals("Beta", response2.header("β"));
+    assertEquals("Γ", response2.header("Gamma"));
+    assertEquals("Delta", response2.header("Δ"));
+    assertEquals("abcd", response2.body().string());
+  }
   private Response get(HttpUrl url) throws IOException {
     Request request = new Request.Builder()
         .url(url)

okhttp-tests/src/test/java/okhttp3/internal/framed/HttpOverSpdyTest.java

@@ -678,6 +678,20 @@ private void noRecoveryFromErrorWithRetryDisabled(ErrorCode errorCode) throws Ex
     }
   }
 
+  @Test public void nonAsciiResponseHeader() throws Exception {
+    server.enqueue(new MockResponse()
+        .addHeaderLenient("Alpha", "α")
+        .addHeaderLenient("β", "Beta"));
+
+    Call call = client.newCall(new Request.Builder()
+        .url(server.url("/"))
+        .build());
+    Response response = call.execute();
+
+    assertEquals("α", response.header("Alpha"));
+    assertEquals("Beta", response.header("β"));
+  }
+
   public Buffer gzip(String bytes) throws IOException {
     Buffer bytesOut = new Buffer();
     BufferedSink sink = Okio.buffer(new GzipSink(bytesOut));

okhttp/src/main/java/okhttp3/internal/http/Http2xStream.java

@@ -28,6 +28,7 @@
 import okhttp3.Request;
 import okhttp3.Response;
 import okhttp3.ResponseBody;
+import okhttp3.internal.Internal;
 import okhttp3.internal.Util;
 import okhttp3.internal.framed.ErrorCode;
 import okhttp3.internal.framed.FramedConnection;
@@ -233,7 +234,7 @@ public static Response.Builder readSpdy3HeadersList(List<Header> headerBlock) th
         } else if (name.equals(VERSION)) {
           version = value;
         } else if (!SPDY_3_SKIPPED_RESPONSE_HEADERS.contains(name)) {
-          headersBuilder.add(name.utf8(), value);
+          Internal.instance.addLenient(headersBuilder, name.utf8(), value);
         }
         start = end + 1;
       }
@@ -260,7 +261,7 @@ public static Response.Builder readHttp2HeadersList(List<Header> headerBlock) th
       if (name.equals(RESPONSE_STATUS)) {
         status = value;
       } else if (!HTTP_2_SKIPPED_RESPONSE_HEADERS.contains(name)) {
-        headersBuilder.add(name.utf8(), value);
+        Internal.instance.addLenient(headersBuilder, name.utf8(), value);
       }
     }
     if (status == null) throw new ProtocolException("Expected ':status' header not present");

okhttp/src/main/java/okhttp3/internal/http/HttpEngine.java

@@ -892,7 +892,7 @@ private static Headers combine(Headers cachedHeaders, Headers networkHeaders) th
         continue; // Drop 100-level freshness warnings.
       }
       if (!OkHeaders.isEndToEnd(fieldName) || networkHeaders.get(fieldName) == null) {
-        result.add(fieldName, value);
+        Internal.instance.addLenient(result, fieldName, value);
       }
     }
 
@@ -902,7 +902,7 @@ private static Headers combine(Headers cachedHeaders, Headers networkHeaders) th
         continue; // Ignore content-length headers of validating responses.
       }
       if (OkHeaders.isEndToEnd(fieldName)) {
-        result.add(fieldName, networkHeaders.value(i));
+        Internal.instance.addLenient(result, fieldName, networkHeaders.value(i));
       }
     }