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HTTP/1.1 Request Framing

ExfilGuard parses HTTP/1.1 request bodies according to RFC 9112. HTTP/1.0 requests are not supported.

  • If Transfer-Encoding is present, it defines the body framing.
  • Else if Content-Length is present, it defines the body length.
  • Else the body length is 0 for HTTP/1.1 keep-alive connections.

If a request has neither Content-Length nor Transfer-Encoding, ExfilGuard treats it as having no body. Any bytes after the header terminator belong to the next request on the same connection. ExfilGuard does not read until EOF, because EOF is only a valid delimiter when the connection is being closed.

Chunked bodies use hexadecimal size lines terminated by CRLF. ExfilGuard validates the complete RFC 9112 chunk-extension grammar, including token and quoted-string values, and forwards valid size lines unchanged. This preserves signed chunk extensions. Bare-LF lines, extra or embedded carriage returns, controls, malformed quoting, and trailing syntax are rejected. Invalid request framing receives a 400 Bad Request response and closes the connection.

The same validation applies to chunked origin responses. If malformed framing is found after the origin response headers have already been sent downstream, ExfilGuard closes the downstream connection instead of appending a second HTTP response.

Legacy or Lenient Upstreams

Some legacy servers treat a missing length as "read until close". On keep-alive connections that can lead to timeouts or other odd behavior. If you must talk to such servers, make sure clients send Content-Length or Transfer-Encoding, or send Connection: close so EOF becomes an explicit delimiter.