net.http: add HTTP/2 frame codec (RFC 7540)#27356
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Add the HTTP/2 binary framing layer: encoders and decoders for all ten frame types plus a fallthrough for unknown types. Like the HPACK PR, this is purely additive (new files in the http module) and does not touch any existing net.http code path; nothing calls it yet. Included: - H2FrameHeader parsing of the 9-byte header, ignoring the reserved bit. - A H2Frame sum type with DATA, HEADERS, PRIORITY, RST_STREAM, SETTINGS, PUSH_PROMISE, PING, GOAWAY, WINDOW_UPDATE, CONTINUATION, and an UnknownFrame variant. Unknown frame types are preserved rather than rejected, as required by RFC 7540 Section 4.1. - h2_read_frame / h2_parse_frame decoders and an .encode() method, with PADDED and PRIORITY handling for HEADERS/DATA/PUSH_PROMISE. - Structural validation that maps to FRAME_SIZE_ERROR / PROTOCOL_ERROR at the connection layer: fixed-size frames (PRIORITY, RST_STREAM, PING, WINDOW_UPDATE), SETTINGS payload as a multiple of 6 with empty ACK, and the stream-id rules (DATA/HEADERS/etc. non-zero; SETTINGS/PING/GOAWAY zero). - H2ErrorCode enum (Section 7) and the SETTINGS identifier and frame type/flag constants. Tests cover an encode/decode round-trip for every frame type, the on-wire header layout, reserved-bit masking, padding decode (including pad length exceeding the frame), the priority section on HEADERS, unknown-frame preservation and re-encoding, reading consecutive frames from one buffer, and the structural validation errors above. Passes under -W -cstrict -cc clang. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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Add comments noting that PRIORITY self-dependency (RFC 7540 Section 5.3.1) and zero WINDOW_UPDATE increments (Section 6.9) are intentionally not rejected by the frame codec. Both are stream errors whose correct handling is RST_STREAM on the affected stream (and, for a zero increment on stream 0, a connection error). That stream-vs-connection distinction belongs to the connection layer, which needs the decoded frame to respond; rejecting in the codec would turn a recoverable stream error into a connection-fatal decode error. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
This was referenced Jun 6, 2026
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* net.http: add synchronous HTTP/2 client connection (H2Conn) Build on the ALPN (#27343), HPACK (#27353), and frame-codec (#27356) PRs to add a minimal, synchronous, single-stream HTTP/2 client. Additive only: new files in the http module, no change to existing code paths. Nothing wires it into http.fetch yet (that ALPN shim is a follow-up), so there is no user-visible behaviour change. - H2Transport interface — the byte transport the connection runs over. Its read/write signatures match net.ssl.SSLConn, so an ALPN-negotiated `h2` TLS socket satisfies it directly; tests use an in-memory mock, so the connection is exercised without a socket. - Connection preface + SETTINGS handshake (sent lazily on the first request). - H2Conn.do(req): HPACK-encodes the request headers, sends HEADERS (plus DATA for a body, chunked to the peer's max frame size and bounded by the connection flow-control window), then reads frames until the stream closes. - Inline servicing of connection-level frames: SETTINGS (apply + ACK), PING (echo ACK), WINDOW_UPDATE (grow the send window), GOAWAY (fail). Receive-side flow control is replenished with a WINDOW_UPDATE per DATA frame. - CONTINUATION reassembly for response header blocks; RST_STREAM on the request stream is surfaced as an error. Hermetic tests over the mock transport cover: a basic GET, a multi-DATA response, a POST with a body, GOAWAY, RST_STREAM, CONTINUATION-split response headers, and PING ACK. Passes under -W -cstrict -cc clang; the full vlib/net/http suite is green. Not included here, by design (follow-ups): stream multiplexing with a background reader thread, connection pooling, wiring into http.fetch via ALPN, and the server side. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com> * net.http: HTTP/2 client header splitting and per-stream flow control Address two send-path correctness gaps in H2Conn: - Split request header blocks larger than the peer's SETTINGS_MAX_FRAME_SIZE into a HEADERS frame followed by CONTINUATION frames (RFC 7540 Section 4.3), via send_header_block. Previously a large header set (e.g. big Cookie or Authorization) was sent as one oversized HEADERS frame that a compliant peer would reject. - Track the per-stream send window in addition to the connection window (RFC 7540 Section 6.9). DATA is now bounded by min(connection, stream) window, stream-level WINDOW_UPDATE credits the active stream, and a change to SETTINGS_INITIAL_WINDOW_SIZE retroactively adjusts the stream window by the delta (Section 6.9.2). Previously only the connection window was tracked, so a peer lowering the initial window or granting stream-level updates could be overrun or could stall the client. Adds tests for a request whose header block spans HEADERS + CONTINUATION, and for a body larger than the initial window that resumes after the peer grows both windows (no DATA frame exceeding the max frame size). Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com> --------- Co-authored-by: Richard Wheeler <quaesitor.scientiam@gmail.com> Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>
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* net.http: add HTTP/2 frame codec (RFC 7540) for HTTP/2 Add the HTTP/2 binary framing layer: encoders and decoders for all ten frame types plus a fallthrough for unknown types. Like the HPACK PR, this is purely additive (new files in the http module) and does not touch any existing net.http code path; nothing calls it yet. Included: - H2FrameHeader parsing of the 9-byte header, ignoring the reserved bit. - A H2Frame sum type with DATA, HEADERS, PRIORITY, RST_STREAM, SETTINGS, PUSH_PROMISE, PING, GOAWAY, WINDOW_UPDATE, CONTINUATION, and an UnknownFrame variant. Unknown frame types are preserved rather than rejected, as required by RFC 7540 Section 4.1. - h2_read_frame / h2_parse_frame decoders and an .encode() method, with PADDED and PRIORITY handling for HEADERS/DATA/PUSH_PROMISE. - Structural validation that maps to FRAME_SIZE_ERROR / PROTOCOL_ERROR at the connection layer: fixed-size frames (PRIORITY, RST_STREAM, PING, WINDOW_UPDATE), SETTINGS payload as a multiple of 6 with empty ACK, and the stream-id rules (DATA/HEADERS/etc. non-zero; SETTINGS/PING/GOAWAY zero). - H2ErrorCode enum (Section 7) and the SETTINGS identifier and frame type/flag constants. Tests cover an encode/decode round-trip for every frame type, the on-wire header layout, reserved-bit masking, padding decode (including pad length exceeding the frame), the priority section on HEADERS, unknown-frame preservation and re-encoding, reading consecutive frames from one buffer, and the structural validation errors above. Passes under -W -cstrict -cc clang. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com> * net.http: document deferred HTTP/2 semantic checks in frame codec Add comments noting that PRIORITY self-dependency (RFC 7540 Section 5.3.1) and zero WINDOW_UPDATE increments (Section 6.9) are intentionally not rejected by the frame codec. Both are stream errors whose correct handling is RST_STREAM on the affected stream (and, for a zero increment on stream 0, a connection error). That stream-vs-connection distinction belongs to the connection layer, which needs the decoded frame to respond; rejecting in the codec would turn a recoverable stream error into a connection-fatal decode error. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com> --------- Co-authored-by: Richard Wheeler <quaesitor.scientiam@gmail.com> Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>
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) * net.http: add synchronous HTTP/2 client connection (H2Conn) Build on the ALPN (vlang#27343), HPACK (vlang#27353), and frame-codec (vlang#27356) PRs to add a minimal, synchronous, single-stream HTTP/2 client. Additive only: new files in the http module, no change to existing code paths. Nothing wires it into http.fetch yet (that ALPN shim is a follow-up), so there is no user-visible behaviour change. - H2Transport interface — the byte transport the connection runs over. Its read/write signatures match net.ssl.SSLConn, so an ALPN-negotiated `h2` TLS socket satisfies it directly; tests use an in-memory mock, so the connection is exercised without a socket. - Connection preface + SETTINGS handshake (sent lazily on the first request). - H2Conn.do(req): HPACK-encodes the request headers, sends HEADERS (plus DATA for a body, chunked to the peer's max frame size and bounded by the connection flow-control window), then reads frames until the stream closes. - Inline servicing of connection-level frames: SETTINGS (apply + ACK), PING (echo ACK), WINDOW_UPDATE (grow the send window), GOAWAY (fail). Receive-side flow control is replenished with a WINDOW_UPDATE per DATA frame. - CONTINUATION reassembly for response header blocks; RST_STREAM on the request stream is surfaced as an error. Hermetic tests over the mock transport cover: a basic GET, a multi-DATA response, a POST with a body, GOAWAY, RST_STREAM, CONTINUATION-split response headers, and PING ACK. Passes under -W -cstrict -cc clang; the full vlib/net/http suite is green. Not included here, by design (follow-ups): stream multiplexing with a background reader thread, connection pooling, wiring into http.fetch via ALPN, and the server side. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com> * net.http: HTTP/2 client header splitting and per-stream flow control Address two send-path correctness gaps in H2Conn: - Split request header blocks larger than the peer's SETTINGS_MAX_FRAME_SIZE into a HEADERS frame followed by CONTINUATION frames (RFC 7540 Section 4.3), via send_header_block. Previously a large header set (e.g. big Cookie or Authorization) was sent as one oversized HEADERS frame that a compliant peer would reject. - Track the per-stream send window in addition to the connection window (RFC 7540 Section 6.9). DATA is now bounded by min(connection, stream) window, stream-level WINDOW_UPDATE credits the active stream, and a change to SETTINGS_INITIAL_WINDOW_SIZE retroactively adjusts the stream window by the delta (Section 6.9.2). Previously only the connection window was tracked, so a peer lowering the initial window or granting stream-level updates could be overrun or could stall the client. Adds tests for a request whose header block spans HEADERS + CONTINUATION, and for a body larger than the initial window that resumes after the peer grows both windows (no DATA frame exceeding the max frame size). Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com> --------- Co-authored-by: Richard Wheeler <quaesitor.scientiam@gmail.com> Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>
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What
Adds the HTTP/2 binary framing layer (RFC 7540 Sections 4 & 6) to
net.http: encoders and decoders for all ten frame types, plus a fallthroughfor unknown types.
Like the HPACK PR (#27353), this is purely additive — new files in the
httpmodule, no changes to any existingnet.httpcode path. Nothing callsit yet, so there is no user-visible behaviour change. It is independent of both
#27353 (HPACK) and #27343 (ALPN) and can be reviewed in parallel.
Files
h2_frame.vH2FrameHeader, the per-type frame structs, theH2Framesum type, decoders (h2_read_frame/h2_parse_frame) and.encode()h2_error.vH2ErrorCodeenum (RFC 7540 Section 7)h2_frame_test.vDesign notes
PUSH_PROMISE, PING, GOAWAY, WINDOW_UPDATE, CONTINUATION) modelled as a
H2Framesum type, plusH2UnknownFrame.so the connection layer can ignore them while still advancing the stream.
on HEADERS are decoded; the encoder never emits padding.
FRAME_SIZE_ERROR/PROTOCOL_ERROR: fixed-size frames (PRIORITY,RST_STREAM, PING, WINDOW_UPDATE), SETTINGS payload as a multiple of 6 with an
empty ACK, and the stream-id rules (DATA/HEADERS non-zero; SETTINGS/PING/
GOAWAY zero).
input buffer.
Tests
h2_frame_test.v(internalmodule httptest) covers:ACK with a payload, bad WINDOW_UPDATE/PING length, DATA on stream 0, SETTINGS
on a non-zero stream.
Roadmap
This is the third of several small, independent PRs building toward HTTP/2,
alongside #27343 (ALPN in net.ssl) and #27353 (HPACK). With framing and HPACK in
place, the next step is the client connection state machine that ties them
together over an ALPN-negotiated
h2TLS socket.🤖 Generated with Claude Code