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Test duplicate Host headers that the mismatch check misses #1343

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Merged
Kriechi merged 2 commits into from
Nov 2, 2026
+30 −1
Merged

Test duplicate Host headers that the mismatch check misses #1343

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2b486a7
Test duplicate Host headers that the mismatch check misses
Nov 1, 2026
b7b20fa
Assert the duplicate Host error message in the test
Nov 1, 2026
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31 changes: 30 additions & 1 deletion tests/test_invalid_headers.py
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Original file line number Diff line number Diff line change
Expand Up @@ -33,6 +33,12 @@ class TestInvalidFrameSequences:
(":method", "GET"),
("user-agent", "someua/0.0.1"),
]
duplicate_host_header_blocks = [
[*base_request_headers, ("host", "example.com"), ("host", "evil.example.com")],
[*base_request_headers, ("host", "evil.example.com"), ("host", "example.com")],
[*[header for header in base_request_headers if header[0] != ":authority"],
("host", "example.com"), ("host", "evil.example.com")],
]
base_invalid_header_blocks = [
[*base_request_headers, ("Uppercase", "name")],
[*base_request_headers, (":late", "pseudo-header")],
Expand All @@ -43,7 +49,7 @@ class TestInvalidFrameSequences:
[*base_request_headers, ("transfer-encoding", "gzip")],
[*base_request_headers, ("upgrade", "super-protocol/1.1")],
[*base_request_headers, ("te", "chunked")],
[*base_request_headers, ("host", "example.com"), ("host", "evil.example.com")],
*duplicate_host_header_blocks,
[*base_request_headers, ("host", "notexample.com")],
[*base_request_headers, (" name", "name with leading space")],
[*base_request_headers, ("name ", "name with trailing space")],
Expand Down Expand Up @@ -88,6 +94,29 @@ def test_headers_event(self, frame_factory, headers) -> None:
)
assert c.data_to_send() == expected_frame.serialize()

@pytest.mark.parametrize("headers", duplicate_host_header_blocks + [
h2.utilities.utf8_encode_headers(headers) for headers in duplicate_host_header_blocks
])
def test_duplicate_host_headers_rejected(self, frame_factory, headers) -> None:
"""
A request header block with more than one Host header is rejected
by the duplicate Host check, not by any other header check.
"""
c = h2.connection.H2Connection(config=self.server_config)
c.receive_data(frame_factory.preamble())
c.clear_outbound_data_buffer()

f = frame_factory.build_headers_frame(headers)
data = f.serialize()

with pytest.raises(h2.exceptions.ProtocolError, match="Request header block has multiple Host headers"):
c.receive_data(data)

expected_frame = frame_factory.build_goaway_frame(
last_stream_id=1, error_code=h2.errors.ErrorCodes.PROTOCOL_ERROR,
)
assert c.data_to_send() == expected_frame.serialize()

@pytest.mark.parametrize("headers", invalid_header_blocks)
def test_push_promise_event(self, frame_factory, headers) -> None:
"""
Expand Down
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