.zip文件在通过gmail api发送并通过zlib压缩后被损坏 [英] .zip file gets corrupted when sent with gmail api and compressed with zlib

问题描述

我正在使用Python 3.7，并使用python的zipfile和zlib压缩.csv文件.

I am using Python 3.7 and compressing a .csv file using python's zipfile and zlib.

import zipfile

filename = "report.csv"

zip_filename = f"{filename[:-4]}.zip"
with zipfile.ZipFile(zip_filename, "w", compression=zipfile.ZIP_DEFLATED) as zip:
    zip.write(filename)

然后将zip文件附加到电子邮件中，我有一些逻辑来确定其MIME类型(我已经检查了它是否正确确定它为application/zip):

The zip file is then attached to an email, I have some logic to determine its MIME type (I have checked that it correctly determines that it's application/zip):

def _make_attachment_part(self, filename: str) -> MIMEBase:
    content_type, encoding = mimetypes.guess_type(filename)
    if content_type is None or encoding is not None:
        content_type = "application/octet-stream"

    main_type, sub_type = content_type.split("/", 1)
    msg = MIMEBase(main_type, sub_type)
    with open(filename, "rb") as f:
        msg.set_payload(f.read())

    base_filename = os.path.basename(filename)
    msg.add_header("Content-Disposition", "attachment", filename=base_filename)

    return msg

然后，为MIMEMultipart类型的message设置主题，收件人，抄送，附件等.然后，我使用base64进行编码并将其发送出去.

Then, the subject, recipients, cc, attachments etc. are set for the message which is of the MIMEMultipart type. Then, I use base64 for encoding and send it through.

raw_message = base64.urlsafe_b64encode(message.as_bytes()).decode()

我收到的附件名称正确且具有预期的大小，但是，当我尝试使用unzip file.zip时，出现以下错误:

I receive my attachment named correctly and of the expected size, however, when I try to use unzip file.zip, I get the following error:

error [file.zip]:  missing 5 bytes in zipfile

有人知道我在做什么错吗?事实上，电子邮件是从Ubuntu计算机发送的，而我正在尝试在MacOS上打开接收到的文件.

Does anyone have any idea what I'm doing wrong? As a matter of fact, the email is sent from Ubuntu machine, whereas I'm trying to open the received file on MacOS.

推荐答案

如 rfc1341 :

7BIT的编码类型要求主体已经采用了7位邮件就绪表示形式.这是默认值，即如果不存在Content-Transfer-Encoding标头字段，则假定为"Content-Transfer-Encoding:7BIT".

An encoding type of 7BIT requires that the body is already in a seven-bit mail- ready representation. This is the default value -- that is, "Content-Transfer-Encoding: 7BIT" is assumed if the Content-Transfer-Encoding header field is not present.

对于您而言，在_make_attachment_part函数中，您要将有效负载设置为MIMEBase对象，但未指定Content-Transfer-Encoding.

In your case, in the _make_attachment_part function, you are setting the payload to your MIMEBase object, but you are not specifying the Content-Transfer-Encoding.

我建议您将有效载荷编码为Base64.您可以按照以下步骤进行操作:

I suggest that you encode your payload as Base64. You can do it as follows:

1. 导入encoders模块

from email import encoders

1. 在_make_attachment_part函数内部，使用encoders模块对有效负载进行编码.

1. Inside your _make_attachment_part function, encode your payload using the encoders module.

def _make_attachment_part(self, filename: str) -> MIMEBase:
    content_type, encoding = mimetypes.guess_type(filename)
    if content_type is None or encoding is not None:
        content_type = "application/octet-stream"

    main_type, sub_type = content_type.split("/", 1)
    msg = MIMEBase(main_type, sub_type)
    with open(filename, "rb") as f:
        msg.set_payload(f.read())

    encoders.encode_base64(msg) # NEW

    base_filename = os.path.basename(filename)
    msg.add_header("Content-Disposition", "attachment", filename=base_filename)

    return msg

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