mirror of
https://github.com/mgeeky/decode-spam-headers.git
synced 2026-02-22 13:33:30 +01:00
117 lines
3.5 KiB
Python
117 lines
3.5 KiB
Python
from __future__ import annotations
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from dataclasses import dataclass
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import re
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@dataclass
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class ParsedHeader:
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index: int
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name: str
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value: str
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class HeaderParser:
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_headers_known_for_breaking_line: set[str] = {
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"Received",
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"Authentication-Results",
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"Received-SPF",
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"DKIM-Signature",
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"X-Google-DKIM-Signature",
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"X-GM-Message-State",
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"Subject",
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"X-MS-Exchange-Organization-ExpirationStartTime",
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"X-MS-Exchange-Organization-Network-Message-Id",
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"X-Forefront-Antispam-Report",
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"X-MS-Exchange-CrossTenant-OriginalArrivalTime",
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"X-Microsoft-Antispam-Mailbox-Delivery",
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"X-Microsoft-Antispam-Message-Info",
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}
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def parse(self, raw_text: str) -> list[ParsedHeader]:
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num = 0
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lines = raw_text.splitlines()
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boundary = ""
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in_boundary = False
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headers: list[ParsedHeader] = []
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i = 0
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while i < len(lines):
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line = lines[i].rstrip("\r")
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if boundary and f"--{boundary}" == line.strip():
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in_boundary = True
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i += 1
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continue
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if in_boundary and f"--{boundary}--" == line.strip():
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in_boundary = False
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i += 1
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continue
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if in_boundary:
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i += 1
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continue
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if line.startswith(" ") or line.startswith("\t"):
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if headers:
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headers[-1].value += "\n" + line
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i += 1
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continue
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stripped = line.strip()
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if not stripped:
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i += 1
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continue
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match = re.match(r"^([^:]+)\s*:\s+(.+)\s*$", stripped, re.S)
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if match:
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headers.append(ParsedHeader(num, match.group(1), match.group(2)))
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num += 1
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else:
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match = re.match(r"^([^:]+)\s*:\s*$", stripped, re.S)
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if match:
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header_name = match.group(1)
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consider_next = header_name in self._headers_known_for_breaking_line
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j = 1
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value_lines: list[str] = []
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if i + 1 < len(lines) and (
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lines[i + 1].startswith(" ")
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or lines[i + 1].startswith("\t")
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or consider_next
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):
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while i + j < len(lines):
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current_line = lines[i + j].rstrip("\r")
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if (
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current_line.startswith(" ")
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or current_line.startswith("\t")
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or consider_next
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):
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value_lines.append(current_line)
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j += 1
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consider_next = False
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else:
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break
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value = "\n".join(value_lines).strip()
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headers.append(ParsedHeader(num, header_name, value))
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num += 1
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if j > 1:
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i += j - 1
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if headers and headers[-1].name.lower() == "content-type":
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boundary_match = re.search(
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r'boundary="([^"]+)"', headers[-1].value, re.I
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)
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if boundary_match:
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boundary = boundary_match.group(1)
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i += 1
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return headers
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