操作说明

• PutObject、AppendObject、PostObject、MultipartUploadPart均会返回对应的crc64值，客户端可以在上传完成后拿到服务器返回的crc64值和本地计算的数值进行校验。
• MultipartComplete时，如果所有的Part都有crc64值，则会返回整个Object的crc64值；若某些Part没有crc64值，则不返回整个Object的crc64值。例如某个Part在crc64上线之前就已经上传，则不返回crc64值。
• GetObject、HeadObject、GetObjectMeta都会返回对应的crc64值（如有）。客户端可以在GetObject完成后，拿到服务器返回的crc64值和本地计算的数值进行校验。
  说明 range get请求返回的将会是整个Object的crc64值。
• Copy相关的操作，如CopyObject、UploadPartCopy，新生成的Object/Part不保证具有crc64值。

应用示例

以下为完整的Python示例代码，演示如何基于crc64值验证数据传输的完整性。

1. 计算crc64。

   import oss2
   from oss2.models import PartInfo
   import os
   import crcmod
   import random
   import string
   do_crc64 = crcmod.mkCrcFun(0x142F0E1EBA9EA3693L, initCrc=0L, xorOut=0xffffffffffffffffL, rev=True)
   def check_crc64(local_crc64, oss_crc64, msg="check crc64"):
   if local_crc64 != oss_crc64:
   print "{0} check crc64 failed. local:{1}, oss:{2}.".format(msg, local_crc64, oss_crc64)
   return False
   else:
   print "{0} check crc64 ok.".format(msg)
   return True
   def random_string(length):
   return ''.join(random.choice(string.lowercase) for i in range(length))
   bucket = oss2.Bucket(oss2.Auth(access_key_id, access_key_secret), endpoint, bucket_name)

2. 验证PutObject。

   content = random_string(1024)
    key = 'normal-key'
    result = bucket.put_object(key, content)
    oss_crc64 = result.headers.get('x-oss-hash-crc64ecma', '')
    local_crc64 = str(do_crc64(content))
    check_crc64(local_crc64, oss_crc64, "put object")

3. 验证GetObject。

   result = bucket.get_object(key)
    oss_crc64 = result.headers.get('x-oss-hash-crc64ecma', '')
    local_crc64 = str(do_crc64(result.resp.read()))
    check_crc64(local_crc64, oss_crc64, "get object")

4. 验证UploadPart和Complete。

   part_info_list = []
    key = "multipart-key"
    result = bucket.init_multipart_upload(key)
    upload_id = result.upload_id
    part_1 = random_string(1024 * 1024)
    result = bucket.upload_part(key, upload_id, 1, part_1)
    oss_crc64 = result.headers.get('x-oss-hash-crc64ecma', '')
    local_crc64 = str(do_crc64(part_1))
    #check 上传的 part 1数据是否完整
    check_crc64(local_crc64, oss_crc64, "upload_part object 1")
    part_info_list.append(PartInfo(1, result.etag, len(part_1)))
    part_2 = random_string(1024 * 1024)
    result = bucket.upload_part(key, upload_id, 2, part_2)
    oss_crc64 = result.headers.get('x-oss-hash-crc64ecma', '')
    local_crc64 = str(do_crc64(part_2))
    #check 上传的 part 2数据是否完整
    check_crc64(local_crc64, oss_crc64, "upload_part object 2")
    part_info_list.append(PartInfo(2, result.etag, len(part_2)))
    result = bucket.complete_multipart_upload(key, upload_id, part_info_list)
    oss_crc64 = result.headers.get('x-oss-hash-crc64ecma', '')
    local_crc64 = str(do_crc64(part_2, do_crc64(part_1)))
    #check 最终oss上的object和本地文件是否一致
    check_crc64(local_crc64, oss_crc64, "complete object")

OSS SDK支持

部分OSS SDK已经支持上传、下载使用crc64进行数据校验，用法见下表中的示例。