fix(session): walk every X-Forwarded-For header line for the client IP - #132
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get_client_ip() read only the first X-Forwarded-For line. A proxy that adds its own line instead of appending to the caller's left a caller-chosen first line in charge of the rightmost-untrusted walk, so a forged address could satisfy ip_binding. All lines are now joined into one chain, as RFC 9110 treats them. The middleware tests built request.headers from a plain dict, which has no getlist(); the forwarded-header ones now use Starlette's Headers. Closes #104
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Closes #104.
Problem
get_client_ip()usedheaders.get("x-forwarded-for"), which returns only the first header line. Some proxies add their ownX-Forwarded-Forline instead of appending to the caller's. The caller's line then stayed first, the rightmost-untrusted walk ran over a value the caller chose, and a forged address could satisfyip_binding.Changes
get_client_ip()joins everyX-Forwarded-Forline with,before walking. RFC 9110 §5.3 treats repeated lines as one comma-separated value.docs/SESSION.mdnotes that multiple lines are read as one chain.[Unreleased]Fixed entry.Tests
test_forwarded_chain_spans_every_header_line: a caller-sent first line plus a proxy-added second line must resolve to the proxy's entry. It fails on the old code and passes with the fix.tests/session/test_middleware.pybuiltrequest.headersfrom a plain dict, which has nogetlist(). They now use Starlette'sHeaders, which is whatRequest.headersactually is.Local results:
zensical build --strict: passes.CACHEX_REQUIRE_LIVE_SERVERS=1against Redis and Memcached: 717 passed, 100% coverage.