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fix: handle CSRF in headers #63

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Merged
jy-tan merged 1 commit into from
Feb 6, 2026
Merged

fix: handle CSRF in headers #63

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11 changes: 11 additions & 0 deletions drift/instrumentation/django/html_utils.py
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Original file line number Diff line number Diff line change
Expand Up @@ -62,6 +62,17 @@ def normalize_csrf_in_body(body: bytes | None) -> bytes | None:
flags=re.IGNORECASE,
)

# Pattern 3: JavaScript CSRF token assignment (e.g., DRF Swagger UI)
# request.headers["X-CSRFTOKEN"] = "ABC123...";
# Also handles single quotes and X-CSRFToken variants
csrf_js_pattern = r'(headers\[["\']X-CSRFTOKEN["\']\]\s*=\s*["\'])[^"\']+(["\'])'
body_str = re.sub(
csrf_js_pattern,
rf"\g<1>{CSRF_PLACEHOLDER}\2",
body_str,
flags=re.IGNORECASE,
)

return body_str.encode("utf-8")

except Exception as e:
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62 changes: 62 additions & 0 deletions tests/unit/test_html_utils.py
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Original file line number Diff line number Diff line change
Expand Up @@ -172,6 +172,68 @@ def test_handles_non_utf8_gracefully(self):
result = normalize_csrf_in_body(html)
assert result == html

def test_normalizes_js_csrf_header_assignment_double_quotes(self):
"""JavaScript CSRF header assignment with double quotes should be normalized."""
html = b"""<script>
const requestInterceptor = (request) => {
request.headers["X-CSRFTOKEN"] = "7180AeP5yScQ72FIE7z8tCtrrQc32Sgaqpqgk8ktVXeBXw7a5qDgXoGgLiWF22Ew";
return request;
};
</script>"""
result = normalize_csrf_in_body(html)
assert result is not None
assert CSRF_PLACEHOLDER.encode() in result
assert b"7180AeP5yScQ72FIE7z8tCtrrQc32Sgaqpqgk8ktVXeBXw7a5qDgXoGgLiWF22Ew" not in result

def test_normalizes_js_csrf_header_assignment_single_quotes(self):
"""JavaScript CSRF header assignment with single quotes should be normalized."""
html = b"""<script>
request.headers['X-CSRFTOKEN'] = 'someToken123';
</script>"""
result = normalize_csrf_in_body(html)
assert result is not None
assert CSRF_PLACEHOLDER.encode() in result
assert b"someToken123" not in result

def test_normalizes_js_csrf_header_case_insensitive(self):
"""JavaScript CSRF header matching should be case-insensitive (X-CSRFToken)."""
html = b"""<script>
request.headers["X-CSRFToken"] = "myToken456";
</script>"""
result = normalize_csrf_in_body(html)
assert result is not None
assert CSRF_PLACEHOLDER.encode() in result
assert b"myToken456" not in result

def test_normalizes_js_csrf_header_preserves_surrounding_js(self):
"""Surrounding JavaScript should be preserved when normalizing CSRF header."""
html = b"""<script>
const requestInterceptor = (request) => {
if (!["GET", undefined].includes(request.method)) {
request.headers["X-CSRFTOKEN"] = "tokenABC";
}
return request;
};
</script>"""
result = normalize_csrf_in_body(html)
assert result is not None
assert b"requestInterceptor" in result
assert b"return request" in result
assert CSRF_PLACEHOLDER.encode() in result
assert b"tokenABC" not in result

def test_normalizes_both_form_and_js_csrf_tokens(self):
"""Both form hidden inputs and JS CSRF header assignments should be normalized."""
html = b"""<html>
<form><input name="csrfmiddlewaretoken" value="formToken123"></form>
<script>request.headers["X-CSRFTOKEN"] = "jsToken456";</script>
</html>"""
result = normalize_csrf_in_body(html)
assert result is not None
assert result.count(CSRF_PLACEHOLDER.encode()) == 2
assert b"formToken123" not in result
assert b"jsToken456" not in result


class TestNormalizeHtmlBody:
"""Tests for normalize_html_body function."""
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