William Grant
83 lines
2.6 KiB
Python
83 lines
2.6 KiB
Python
# This software is provided 'as-is', without any express or implied
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# warranty. In no event will the author be held liable for any damages
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# arising from the use of this software.
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#
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# Permission is granted to anyone to use this software for any purpose,
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# including commercial applications, and to alter it and redistribute it
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# freely, subject to the following restrictions:
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#
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# 1. The origin of this software must not be misrepresented; you must not
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# claim that you wrote the original software. If you use this software
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# in a product, an acknowledgment in the product documentation would be
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# appreciated but is not required.
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# 2. Altered source versions must be plainly marked as such, and must not be
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# misrepresented as being the original software.
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# 3. This notice may not be removed or altered from any source distribution.
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#
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# Copyright (c) 2008 Greg Hewgill http://hewgill.com
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#
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# This has been modified from the original software.
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# Copyright (c) 2011 William Grant <me@williamgrant.id.au>
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import re
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def strip_trailing_whitespace(content):
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return re.sub(b"[\t ]+\r\n", b"\r\n", content)
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def compress_whitespace(content):
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return re.sub(b"[\t ]+", b" ", content)
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def strip_trailing_lines(content):
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return re.sub(b"(\r\n)*$", b"\r\n", content)
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def unfold_header_value(content):
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return re.sub(b"\r\n", b"", content)
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class Simple:
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"""Class that represents the "simple" canonicalization algorithm."""
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name = b"simple"
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@staticmethod
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def canonicalize_headers(headers):
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# No changes to headers.
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return headers
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@staticmethod
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def canonicalize_body(body):
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# Ignore all empty lines at the end of the message body.
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return strip_trailing_lines(body)
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class Relaxed:
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"""Class that represents the "relaxed" canonicalization algorithm."""
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name = b"relaxed"
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@staticmethod
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def canonicalize_headers(headers):
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# Convert all header field names to lowercase.
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# Unfold all header lines.
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# Compress WSP to single space.
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# Remove all WSP at the start or end of the field value (strip).
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return [
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(x[0].lower().rstrip(),
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compress_whitespace(unfold_header_value(x[1])).strip() + b"\r\n")
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for x in headers]
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@staticmethod
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def canonicalize_body(body):
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# Remove all trailing WSP at end of lines.
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# Compress non-line-ending WSP to single space.
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# Ignore all empty lines at the end of the message body.
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return strip_trailing_lines(
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compress_whitespace(strip_trailing_whitespace(body)))
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algorithms = dict((c.name, c) for c in (Simple, Relaxed))
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