Added crc32 checksuming support

Author: ShreyasSinha

google-cloud-storage/src/main/java/com/google/cloud/storage/MultipartUploadClientImpl.java

@@ -30,6 +30,8 @@
 import com.google.cloud.storage.multipartupload.model.CreateMultipartUploadResponse;
 import com.google.cloud.storage.multipartupload.model.UploadPartRequest;
 import com.google.cloud.storage.multipartupload.model.UploadPartResponse;
+import com.google.common.hash.HashCode;
+import com.google.common.hash.Hashing;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
@@ -38,6 +40,7 @@
 import java.net.URI;
 import java.net.URL;
 import java.net.URLEncoder;
+import java.nio.ByteBuffer;
 import java.nio.charset.StandardCharsets;
 import java.security.MessageDigest;
 import java.security.NoSuchAlgorithmException;
@@ -134,11 +137,17 @@ public CompleteMultipartUploadResponse completeMultipartUpload(CompleteMultipart
 
     MessageDigest md = MessageDigest.getInstance("MD5");
     String contentMd5 = Base64.getEncoder().encodeToString(md.digest(xmlBodyBytes));
+
+    HashCode crc32cHash = Hashing.crc32c().hashBytes(xmlBodyBytes);
+    byte[] crc32cBytes = ByteBuffer.allocate(4).putInt(crc32cHash.asInt()).array();
+    String crc32cBase64 = Base64.getEncoder().encodeToString(crc32cBytes);
+
     String date = getRfc1123Date();
     String contentType = "application/xml";
+    String canonicalizedHeaders = "x-goog-hash:crc32c=" + crc32cBase64 + "\n";
 
     // GCS Signature Rule #3: The query string IS NOT included for the POST complete request.
-    String signature = signRequest("POST", contentMd5, contentType, date, resourcePath, GOOGLE_SECRET_KEY);
+    String signature = signRequest("POST", contentMd5, contentType, date, canonicalizedHeaders, resourcePath, GOOGLE_SECRET_KEY);
     String authHeader = "GOOG1 " + GOOGLE_ACCESS_KEY + ":" + signature;
 
     HttpURLConnection connection = (HttpURLConnection) new URL(uri).openConnection();
@@ -147,6 +156,7 @@ public CompleteMultipartUploadResponse completeMultipartUpload(CompleteMultipart
     connection.setRequestProperty("Authorization", authHeader);
     connection.setRequestProperty("Content-Type", contentType);
     connection.setRequestProperty("Content-MD5", contentMd5);
+    connection.setRequestProperty("x-goog-hash", "crc32c=" + crc32cBase64);
     connection.setFixedLengthStreamingMode(xmlBodyBytes.length);
     connection.setDoOutput(true);
 

google-cloud-storage/src/main/java/com/google/cloud/storage/MultipartUploadUtility.java

@@ -43,8 +43,12 @@ public static String readStream(InputStream inputStream) throws IOException {
   }
 
   public static String signRequest(String httpVerb, String contentMd5, String contentType, String date, String canonicalizedResource, String googleSecretKey) {
+    return signRequest(httpVerb, contentMd5, contentType, date, "", canonicalizedResource, googleSecretKey);
+  }
+
+  public static String signRequest(String httpVerb, String contentMd5, String contentType, String date, String canonicalizedHeaders, String canonicalizedResource, String googleSecretKey) {
     try {
-      String stringToSign = httpVerb + "\n" + contentMd5 + "\n" + contentType + "\n" + date + "\n" + canonicalizedResource;
+      String stringToSign = httpVerb + "\n" + contentMd5 + "\n" + contentType + "\n" + date + "\n" + canonicalizedHeaders + canonicalizedResource;
       Mac sha1Hmac = Mac.getInstance("HmacSHA1");
       SecretKeySpec secretKey = new SecretKeySpec(googleSecretKey.getBytes(StandardCharsets.UTF_8), "HmacSHA1");
       sha1Hmac.init(secretKey);