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fix: strip hop-by-hop headers from bidirectional response #7

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Merged
evgenizb merged 1 commit into from
Jun 3, 2026
Merged

fix: strip hop-by-hop headers from bidirectional response #7

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22 changes: 21 additions & 1 deletion cm_proxy/proxy.py
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Original file line number Diff line number Diff line change
Expand Up @@ -304,6 +304,26 @@ def request(self, payload):
)


HOP_BY_HOP_HEADERS = frozenset(
{
"connection",
"keep-alive",
"proxy-authenticate",
"proxy-authorization",
"te",
"trailer",
"transfer-encoding",
"upgrade",
"content-length",
"content-encoding",
}
)
Comment on lines +307 to +320

@gemini-code-assist gemini-code-assist Bot Jun 3, 2026

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medium

The non-standard but widely used Proxy-Connection header behaves similarly to the standard Connection header and is often sent by older proxies or clients. To prevent potential hanging or connection issues, it is safer to include "proxy-connection" in the set of hop-by-hop headers to be filtered out.

Suggested change
HOP_BY_HOP_HEADERS = frozenset(
{
"connection",
"keep-alive",
"proxy-authenticate",
"proxy-authorization",
"te",
"trailer",
"transfer-encoding",
"upgrade",
"content-length",
"content-encoding",
}
)
HOP_BY_HOP_HEADERS = frozenset(
{
"connection",
"keep-alive",
"proxy-authenticate",
"proxy-authorization",
"proxy-connection",
"te",
"trailer",
"transfer-encoding",
"upgrade",
"content-length",
"content-encoding",
}
)



def filter_response_headers(headers):
return {k: v for k, v in headers.items() if k.lower() not in HOP_BY_HOP_HEADERS}
Comment on lines +323 to +324

@gemini-code-assist gemini-code-assist Bot Jun 3, 2026

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medium

To ensure robustness and adhere to defensive programming practices, it is safer to handle cases where headers might be None or empty (for example, in unit tests or mock environments) by returning an empty dictionary early.

Suggested change
def filter_response_headers(headers):
return {k: v for k, v in headers.items() if k.lower() not in HOP_BY_HOP_HEADERS}
def filter_response_headers(headers):
if not headers:
return {}
return {k: v for k, v in headers.items() if k.lower() not in HOP_BY_HOP_HEADERS}



class BidirectionalHandler(UnidirectionalHandler):
def __init__(self, local_endpoint):
super().__init__(local_endpoint)
Expand All @@ -315,7 +335,7 @@ def forward_message(self, message):
token = message_data.get("Token")
result = {
"statusCode": response.status_code,
"headers": dict(response.headers),
"headers": filter_response_headers(response.headers),
"body": response.text,
"isBase64Encoded": False,
}
Expand Down