blackbull.fault_injection.catalogue.h2

blackbull.fault_injection.catalogue.h2

Named HTTP/2 server faults; each builder returns a ScenarioH2.

exhausted_window_zero_initial()

Server advertises SETTINGS_INITIAL_WINDOW_SIZE = 0.

RFC 9113 §6.9.2 — a zero initial window means the client cannot send any DATA bytes until the server grants WINDOW_UPDATE. This scenario never grants WINDOW_UPDATE, so a client trying to send a request body must respect the zero window rather than spin or flood the wire.

half_closed_after_headers()

Server sends a complete HEADERS, then FIN without a GOAWAY.

RFC 9113 §5.1 — a stream the server has not ended, on a connection the server stops writing to without saying why. Distinct from CloseGracefully, which sends GOAWAY first and tells the client which streams were processed: here the client learns only that no more frames are coming, and must decide for itself that an unterminated stream cannot complete.

A client that waits for a GOAWAY it will never receive, or that treats the FIN as a reset, differs observably from one that reads EOF and fails the outstanding request.

half_closed_stream_no_data()

Server sends HEADERS without END_STREAM, then nothing.

A real H2 server would follow HEADERS with DATA + END_STREAM. This scenario stops mid-stream — flags END_HEADERS but not END_STREAM, then sleeps until the client gives up. Clients must time out or RST_STREAM rather than block forever.

headers_continuation_dropped()

Server sends HEADERS without END_HEADERS, then no CONTINUATION.

RFC 9113 §6.2 / §6.10 — HEADERS without END_HEADERS MUST be followed by CONTINUATION frames for the same stream until one sets END_HEADERS. This scenario sends the partial HEADERS and then nothing, leaving the stream in an unresolved header-block state. Clients must enforce a timeout (or PROTOCOL_ERROR on intervening frame for a different stream) rather than hang indefinitely.

settings_max_frame_size_below_minimum()

Server advertises SETTINGS_MAX_FRAME_SIZE below the legal floor.

RFC 9113 §6.5.2 — SETTINGS_MAX_FRAME_SIZE values below 16_384 are a PROTOCOL_ERROR. The client must close the connection with PROTOCOL_ERROR rather than try to honour the illegal value (e.g. splitting frames into 1-byte chunks).