如何确定邮件头是否是base64编码 [英] how can I determine whether an email header is base64 encoded

问题描述

使用email.header包，我可以执行

Using the email.header package, I can do

the_text,the_charset = decode_header(inputText)

获取电子邮件标题的字符集，其中inputText由诸如

to get the character set of the email header, where the inputText was retrieved by a command like

inputText = msg.get('From')

以使用From：头为例。

to use the From: header as an example.

为了提取该标题的标题编码，我需要这样做吗？：

in order to extract the header encoding for that header, do I have to do something like this?:

the_header_encoding = email.charset.Charset(the_charset).header_encoding

That is, do I have to create an instance of the Charset class based on the name of the charset (and would that even work?), or is there a way to extract the header encoding more directly from the header itself?

推荐答案

Encoded-Message 标题可以由1行或更多行组成，每一行都可以使用不同的编码，也可以不使用任何编码。

Encoded-Message header can consist of 1 or more lines, and each line can use a different encoding, or no encoding at all.

我们必须自己解析编码类型，每行一个。使用正则表达式：

You'll have to parse the type of encoding out yourself, one per line. Using a regular expression:

import re

quopri_entry = re.compile(r'=\?[\w-]+\?(?P<encoding>[QB])\?[^?]+?\?=', flags=re.I)
encodings = {'Q': 'quoted-printable', 'B': 'base64'}

def encoded_message_codecs(header):
    used = []
    for line in header.splitlines():
        entry = quopri_entry.search(line)
        if not entry:
            used.append(None)
            continue
        used.append(encodings.get(entry.group('encoding').upper(), 'unknown'))
    return used

这将返回从 quoted-printable ， base64 ， unknown 或无如果该行没有使用Encoded-Message。

This returns a list of strings drawn from quoted-printable, base64, unknown or None if no Encoded-Message was used for that line.

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