anti
19ceff4417
Seven instrumenters that mutate operator-supplied artifacts to
embed the callback URL:
- passthrough — bytes unchanged; only DNS-callback tokens trip
detection, with the slug embedded in the placement path
- plain — substitutes {{CANARY_URL}}/{{CANARY_HOST}} placeholders;
falls back to appending a comment line whose prefix adapts to the
apparent file syntax (#, //, ;)
- html — injects a 1x1 tracking pixel before </body>, appends
if the close tag is missing
- docx — direct zipfile manipulation (no python-docx dep):
inserts an external-image Relationship into word/_rels/document.xml.rels
and a matching <w:drawing> element before </w:body>
- xlsx — sibling of docx; injects an external-image relationship
into xl/_rels/workbook.xml.rels (orphan rels are still fetched on
open by most viewers)
- pdf — uses pikepdf to install /OpenAction /URI on the catalog;
rejects with a clear message when pikepdf isn't installed
- image — uses Pillow to embed slug + URL in PNG tEXt / JPEG
comment; rejects with a clear message when Pillow isn't installed
DOCX and XLSX share the rId allocator + relationship injector via
the docx module; both work on stdlib zipfile only.
Tests synthesise minimal real DOCX/XLSX fixtures inline, round-trip
each instrumenter, and assert the callback URL ends up in the
mutated bytes while the file still parses.
46 lines
1.5 KiB
Python
46 lines
1.5 KiB
Python
"""HTML instrumenter — append a 1×1 tracking pixel.
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Stdlib-only. We don't parse the HTML; we just inject the ``<img>``
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tag immediately before the closing ``</body>`` (or, failing that, at
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the end of the document). Most renderers that support remote images
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(email previewers, IDE doc previews, browsers) will fetch it as
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soon as the document is opened.
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"""
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from __future__ import annotations
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import re
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from decnet.canary.base import CanaryArtifact, CanaryContext, CanaryInstrumenter
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_BODY_CLOSE = re.compile(rb"</body\s*>", re.IGNORECASE)
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class HtmlInstrumenter(CanaryInstrumenter):
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name = "html"
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mime_prefixes = ("text/html", "application/xhtml+xml")
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def instrument(
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self, blob: bytes, ctx: CanaryContext, *, target_path: str,
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) -> CanaryArtifact:
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url = f"{ctx.http_base.rstrip('/')}/c/{ctx.callback_token}".encode()
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pixel = (
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b"<img src=\"" + url + b"\" width=\"1\" height=\"1\" "
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b"alt=\"\" style=\"display:none\">\n"
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)
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match = _BODY_CLOSE.search(blob)
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if match:
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out = blob[:match.start()] + pixel + blob[match.start():]
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note = "injected 1x1 pixel before </body>"
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else:
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out = (blob if blob.endswith(b"\n") else blob + b"\n") + pixel
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note = "appended 1x1 pixel (no </body> found)"
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return CanaryArtifact(
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path=target_path,
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content=out,
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mode=0o644,
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mtime_offset=-86400 * 7,
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instrumenter=self.name,
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notes=[note, f"pixel src={url.decode()}"],
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)
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