CharacterEncoding fix in AwsProxyHttpServletRequest

Fix to address issue #5. Also added a unit test for the fix in the
spring support repo.

Author: sapessi

aws-serverless-java-container-core/src/main/java/com/amazonaws/serverless/proxy/internal/servlet/AwsProxyHttpServletRequest.java

@@ -79,6 +79,7 @@ public class AwsProxyHttpServletRequest
     private static final String FORM_DATA_SEPARATOR = "&";
     private static final String DEFAULT_CHARACTER_ENCODING = "UTF-8";
     private static final String HEADER_DATE_FORMAT = "EEE, d MMM yyyy HH:mm:ss z";
+    private static final String ENCODING_VALUE_KEY = "charset";
 
     // We need this to pickup the protocol from the CloudFront header since Lambda doesn't receive this
     // information from anywhere else
@@ -382,15 +383,60 @@ public Enumeration<String> getAttributeNames() {
 
     @Override
     public String getCharacterEncoding() {
-        return getHeaderCaseInsensitive(HttpHeaders.ACCEPT_ENCODING);
+        // we only look at content-type because content-encoding should only be used for
+        // "binary" requests such as gzip/deflate.
+        String contentTypeHeader = getHeaderCaseInsensitive(HttpHeaders.CONTENT_TYPE);
+        if (contentTypeHeader == null) {
+            return null;
+        }
+
+        String[] contentTypeValues = contentTypeHeader.split(HEADER_VALUE_SEPARATOR);
+        if (contentTypeValues.length <= 1) {
+            return null;
+        }
+
+        for (String contentTypeValue : contentTypeValues) {
+            if (contentTypeValue.trim().startsWith(ENCODING_VALUE_KEY)) {
+                String[] encodingValues = contentTypeValue.split(HEADER_KEY_VALUE_SEPARATOR);
+                if (encodingValues.length <= 1) {
+                    return null;
+                }
+                return encodingValues[1];
+            }
+        }
+        return null;
     }
 
 
     @Override
     public void setCharacterEncoding(String s) throws UnsupportedEncodingException {
-        request.getHeaders().put(HttpHeaders.ACCEPT_ENCODING, s);
-    }
+        String currentContentType = request.getHeaders().get(HttpHeaders.CONTENT_TYPE);
+        if (currentContentType == null) {
+            request.getHeaders().put(
+                    HttpHeaders.CONTENT_TYPE,
+                    HEADER_VALUE_SEPARATOR + " " + ENCODING_VALUE_KEY + HEADER_KEY_VALUE_SEPARATOR + s);
+            return;
+        }
+
+        if (currentContentType.contains(HEADER_VALUE_SEPARATOR)) {
+            String[] contentTypeValues = currentContentType.split(HEADER_VALUE_SEPARATOR);
+            String contentType = contentTypeValues[0];
+
+            for (String contentTypeValue : contentTypeValues) {
+                if (contentTypeValue.trim().startsWith(ENCODING_VALUE_KEY)) {
+                    contentType += HEADER_VALUE_SEPARATOR + " " + ENCODING_VALUE_KEY + HEADER_KEY_VALUE_SEPARATOR + s;
+                } else {
+                    contentType += HEADER_VALUE_SEPARATOR + " " + contentTypeValue;
+                }
+            }
 
+            request.getHeaders().put(HttpHeaders.CONTENT_TYPE, contentType);
+        } else {
+            request.getHeaders().put(
+                    HttpHeaders.CONTENT_TYPE,
+                    currentContentType + HEADER_VALUE_SEPARATOR + " " + ENCODING_VALUE_KEY + HEADER_KEY_VALUE_SEPARATOR + s);
+        }
+    }
 
     @Override
     public int getContentLength() {

aws-serverless-java-container-spring/src/test/java/com/amazonaws/serverless/proxy/spring/SpringAwsProxyTest.java

@@ -19,6 +19,8 @@
 import org.springframework.test.context.support.DependencyInjectionTestExecutionListener;
 import org.springframework.test.context.web.WebAppConfiguration;
 
+import javax.ws.rs.core.HttpHeaders;
+import javax.ws.rs.core.MediaType;
 import java.io.IOException;
 import java.util.UUID;
 
@@ -165,6 +167,26 @@ public void base64_binaryResponse_base64Encoding() {
         assertTrue(Base64.isBase64(response.getBody()));
     }
 
+    @Test
+    public void servletRequestEncoding_acceptEncoding_okStatusCode() {
+        SingleValueModel singleValueModel = new SingleValueModel();
+        singleValueModel.setValue(CUSTOM_HEADER_VALUE);
+        AwsProxyRequest request = null;
+        try {
+            request = new AwsProxyRequestBuilder("/echo/json-body", "POST")
+                    .header(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_JSON)
+                    .header(HttpHeaders.ACCEPT_ENCODING, "gzip, deflate")
+                    .queryString("status", "200")
+                    .body(objectMapper.writeValueAsString(singleValueModel))
+                    .build();
+        } catch (JsonProcessingException e) {
+            fail("Could not serialize object to JSON");
+        }
+
+        AwsProxyResponse output = handler.proxy(request, lambdaContext);
+        assertEquals(200, output.getStatusCode());
+    }
+
     private void validateMapResponseModel(AwsProxyResponse output) {
         try {
             MapResponseModel response = objectMapper.readValue(output.getBody(), MapResponseModel.class);