changed the behavior of the getMimeType method to always try to load the mime type from the file name, without probing the file system. Updated unit tests to match (#254)

Author: sapessi

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

@@ -20,6 +20,7 @@
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import javax.activation.MimetypesFileTypeMap;
 import javax.servlet.Filter;
 import javax.servlet.FilterRegistration;
 import javax.servlet.RequestDispatcher;
@@ -72,6 +73,7 @@ public class AwsServletContext
     private Map<String, String> initParameters;
     private AwsLambdaServletContainerHandler containerHandler;
     private Logger log = LoggerFactory.getLogger(AwsServletContext.class);
+    private MimetypesFileTypeMap mimeTypes; // lazily loaded in the getMimeType method
 
 
     //-------------------------------------------------------------
@@ -142,13 +144,16 @@ public int getEffectiveMinorVersion() {
     @Override
     @SuppressFBWarnings("PATH_TRAVERSAL_IN") // suppressing because we are using the getValidFilePath
     public String getMimeType(String s) {
-        try {
-            String validatedPath = SecurityUtils.getValidFilePath(s);
-            return Files.probeContentType(Paths.get(validatedPath));
-        } catch (IOException e) {
-            log.warn("Could not find content type for file:  " + SecurityUtils.encode(s), e);
+        if (!s.contains(".")) {
             return null;
         }
+        if (mimeTypes == null) {
+            mimeTypes = new MimetypesFileTypeMap();
+        }
+        // TODO: The getContentType method of the MimetypesFileTypeMap returns application/octet-stream
+        // instead of null when the type cannot be found. We should replace with an implementation that
+        // loads the System mime types ($JAVA_HOME/lib/mime.types
+        return mimeTypes.getContentType(s);
     }
 
 
@@ -232,7 +237,7 @@ public String getRealPath(String s) {
             try {
                 absPath = new File(fileUrl.toURI()).getAbsolutePath();
             } catch (URISyntaxException e) {
-                log.error("Error while looking for real path: {}", SecurityUtils.encode(s), SecurityUtils.encode(e.getMessage()));
+                log.error("Error while looking for real path {}: {}", SecurityUtils.encode(s), SecurityUtils.encode(e.getMessage()));
             }
         }
         return absPath;

aws-serverless-java-container-core/src/test/java/com/amazonaws/serverless/proxy/internal/servlet/AwsServletContextTest.java

@@ -4,6 +4,7 @@
 import com.amazonaws.serverless.proxy.internal.servlet.filters.UrlPathValidator;
 
 import org.junit.BeforeClass;
+import org.junit.Ignore;
 import org.junit.Test;
 
 import javax.servlet.Filter;
@@ -43,7 +44,7 @@ public static void setUp() {
         LambdaContainerHandler.getContainerConfig().addValidFilePath("C:\\MyTestFolder");
     }
 
-    @Test
+    @Test @Ignore
     public void getMimeType_disabledPath_expectException() {
         AwsServletContext ctx = new AwsServletContext(null);
         try {
@@ -64,7 +65,7 @@ public void getMimeType_nonExistentFileInTaskPath_expectNull() {
 
     @Test
     public void getMimeType_mimeTypeOfCorrectFile_expectMime() {
-        String tmpFilePath = TMP_DIR + "/test_text.txt";
+        String tmpFilePath = TMP_DIR + "test_text.txt";
         try {
             System.out.println("Writing to tmp file " + tmpFilePath);
             PrintWriter tmpWriter = new PrintWriter(tmpFilePath, "UTF-8");
@@ -73,23 +74,27 @@ public void getMimeType_mimeTypeOfCorrectFile_expectMime() {
 
             AwsServletContext ctx = new AwsServletContext(null);
             String mimeType = ctx.getMimeType(tmpFilePath);
-            String deducedMimeType = Files.probeContentType(Paths.get(tmpFilePath));
-            assertEquals(deducedMimeType, mimeType);
+            assertEquals("text/plain", mimeType);
 
             mimeType = ctx.getMimeType("file://" + tmpFilePath);
-            assertEquals(deducedMimeType, mimeType);
+            assertEquals("text/plain", mimeType);
         } catch (FileNotFoundException e) {
             fail("tmp file not found");
             e.printStackTrace();
         } catch (UnsupportedEncodingException e) {
             fail("Unsupported encoding");
             e.printStackTrace();
-        } catch (IOException e) {
-            fail("Failed to prove tmp file content type");
-            e.printStackTrace();
         }
     }
 
+    @Test
+    public void getMimeType_unknownExtension_expectAppOctetStream() {
+        AwsServletContext ctx = new AwsServletContext(null);
+        String mimeType = ctx.getMimeType("myfile.unkext");
+        assertEquals("application/octet-stream", mimeType);
+    }
+
+
     @Test
     public void addFilter_nonExistentFilterClass_expectException() {
         AwsServletContext ctx = new AwsServletContext(null);