unikernel/duniverse/ocaml-h2/lib/frame.ml

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+(*----------------------------------------------------------------------------
+ *  Copyright (c) 2019 António Nuno Monteiro
+ *
+ *  All rights reserved.
+ *
+ *  Redistribution and use in source and binary forms, with or without
+ *  modification, are permitted provided that the following conditions are met:
+ *
+ *  1. Redistributions of source code must retain the above copyright notice,
+ *  this list of conditions and the following disclaimer.
+ *
+ *  2. Redistributions in binary form must reproduce the above copyright
+ *  notice, this list of conditions and the following disclaimer in the
+ *  documentation and/or other materials provided with the distribution.
+ *
+ *  3. Neither the name of the copyright holder nor the names of its
+ *  contributors may be used to endorse or promote products derived from this
+ *  software without specific prior written permission.
+ *
+ *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ *  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ *  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ *  ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ *  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ *  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ *  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ *  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ *  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ *  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ *  POSSIBILITY OF SUCH DAMAGE.
+ *---------------------------------------------------------------------------*)
+
+let connection_preface = "PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n"
+
+module FrameType = struct
+  type t =
+    (* From RFC7540§6.1:
+     *   DATA frames (type=0x0) convey arbitrary, variable-length sequences
+     *   of octets associated with a stream. *)
+    | Data
+    (* From RFC7540§6.2:
+     *   The HEADERS frame (type=0x1) is used to open a stream (Section 5.1),
+     *   and additionally carries a header block fragment. *)
+    | Headers
+    (* From RFC7540§6.3:
+     *   The PRIORITY frame (type=0x2) specifies the sender-advised priority
+     *   of a stream (Section 5.3). *)
+    | Priority
+    (* From RFC7540§6.4:
+     *   The RST_STREAM frame (type=0x3) allows for immediate termination of
+     *   a stream. *)
+    | RSTStream
+    (* From RFC7540§6.5:
+     *   The SETTINGS frame (type=0x4) conveys configuration parameters that
+     *   affect how endpoints communicate, such as preferences and
+     *   constraints on peer behavior. *)
+    | Settings
+    (* From RFC7540§6.6:
+     *   The PUSH_PROMISE frame (type=0x5) is used to notify the peer
+     *   endpoint in advance of streams the sender intends to initiate. *)
+    | PushPromise
+    (* From RFC7540§6.7:
+     *   The PING frame (type=0x6) is a mechanism for measuring a minimal
+     *   round-trip time from the sender, as well as determining whether an
+     *   idle connection is still functional. *)
+    | Ping
+    (* From RFC7540§6.8:
+     *   The GOAWAY frame (type=0x7) is used to initiate shutdown of a
+     *   connection or to signal serious error conditions. *)
+    | GoAway
+    (* From RFC7540§6.9:
+     *   The WINDOW_UPDATE frame (type=0x8) is used to implement flow
+     *   control; [...]. *)
+    | WindowUpdate
+    (* From RFC7540§6.10:
+     *   The CONTINUATION frame (type=0x9) is used to continue a sequence of
+     *   header block fragments (Section 4.3). *)
+    | Continuation
+    (* From RFC7540§5.1:
+     *   Frames of unknown types are ignored. *)
+    | Unknown of int
+
+  let serialize = function
+    | Data -> 0
+    | Headers -> 1
+    | Priority -> 2
+    | RSTStream -> 3
+    | Settings -> 4
+    | PushPromise -> 5
+    | Ping -> 6
+    | GoAway -> 7
+    | WindowUpdate -> 8
+    | Continuation -> 9
+    | Unknown x -> x
+
+  let parse = function
+    | 0 -> Data
+    | 1 -> Headers
+    | 2 -> Priority
+    | 3 -> RSTStream
+    | 4 -> Settings
+    | 5 -> PushPromise
+    | 6 -> Ping
+    | 7 -> GoAway
+    | 8 -> WindowUpdate
+    | 9 -> Continuation
+    | x -> Unknown x
+end
+
+(* From RFC7540§4.1:
+ *   The fields of the frame header are defined as:
+ *
+ *     Length: The length of the frame payload expressed as an unsigned 24-bit
+ *             integer. [...]
+ *
+ *     Type: The 8-bit type of the frame. [...]
+ *
+ *     Flags: An 8-bit field reserved for boolean flags specific to the frame
+ *            type. [...]
+ *
+ *     Stream Identifier: A stream identifier (see Section 5.1.1) expressed as
+ *                        an unsigned 31-bit integer. [...] *)
+type frame_header =
+  { payload_length : int
+  ; flags : Flags.t
+  ; stream_id : Stream_identifier.t
+  ; frame_type : FrameType.t
+  }
+
+(* From RFC7540§4.1:
+ *   The structure and content of the frame payload is dependent entirely on
+ *   the frame type. *)
+type frame_payload =
+  (* From RFC7540§6.1:
+   *   The DATA frame contains the following fields:
+   *
+   *   [...]
+   *
+   *   Data: Application data. The amount of data is the remainder of the
+   *         frame payload after subtracting the length of the other fields
+   *         that are present. *)
+  | Data of Bigstringaf.t
+  (* From RFC7540§6.2:
+   *   The HEADERS frame payload has the following fields:
+   *
+   *    E: A single-bit flag indicating that the stream dependency is
+   *       exclusive (see Section 5.3). [...]
+   *
+   *    Stream Dependency: A 31-bit stream identifier for the stream that
+   *                       this stream depends on (see Section 5.3). [...]
+   *
+   *    Weight: An unsigned 8-bit integer representing a priority weight for
+   *            the stream (see Section 5.3). [...] This field is only
+   *            present if the PRIORITY flag is set.
+   *
+   *    Header Block Fragment: A header block fragment (Section 4.3). *)
+  | Headers of Priority.t * Bigstringaf.t
+  (* From RFC7540§6.3:
+   *   The payload of a PRIORITY frame contains the following fields:
+   *
+   *   E: A single-bit flag indicating that the stream dependency is
+   *      exclusive (see Section 5.3).
+   *
+   *   Stream Dependency: A 31-bit stream identifier for the stream that this
+   *                      stream depends on (see Section 5.3).
+   *
+   *   Weight: An unsigned 8-bit integer representing a priority weight for
+   *           the stream (see Section 5.3). [...] *)
+  | Priority of Priority.t
+  (* From RFC7540§6.4:
+   *   The RST_STREAM frame contains a single unsigned, 32-bit integer
+   *   identifying the error code (Section 7). [...] *)
+  | RSTStream of Error_code.t
+  (* From RFC7540§6.5:
+   *   The payload of a SETTINGS frame consists of zero or more parameters,
+   *   each consisting of an unsigned 16-bit setting identifier and an
+   *   unsigned 32-bit value. *)
+  | Settings of Settings.settings_list
+  (* From RFC7540§6.6:
+   *   The PUSH_PROMISE frame includes the unsigned 31-bit identifier of the
+   *   stream the endpoint plans to create along with a set of headers that
+   *   provide additional context for the stream. *)
+  | PushPromise of Stream_identifier.t * Bigstringaf.t
+  (* From RFC7540§6.7:
+   *   In addition to the frame header, PING frames MUST contain 8 octets of
+   *   opaque data in the payload. A sender can include any value it chooses
+   *   and use those octets in any fashion. *)
+  | Ping of Bigstringaf.t
+  (* From RFC7540§6.8:
+   *   The last stream identifier in the GOAWAY frame contains the
+   *   highest-numbered stream identifier for which the sender of the GOAWAY
+   *   frame might have taken some action on or might yet take action on.
+   *
+   *   [...] The GOAWAY frame also contains a 32-bit error code (Section 7)
+   *   that contains the reason for closing the connection.
+   *
+   *   [...] Endpoints MAY append opaque data to the payload of any GOAWAY
+   *   frame. *)
+  | GoAway of Stream_identifier.t * Error_code.t * Bigstringaf.t
+  (* From RFC7540§6.9:
+   *   The payload of a WINDOW_UPDATE frame is one reserved bit plus an
+   *   unsigned 31-bit integer indicating the number of octets that the
+   *   sender can transmit in addition to the existing flow-control
+   *   window. *)
+  | WindowUpdate of Settings.WindowSize.t
+  (* From RFC7540§6.10:
+   *   The CONTINUATION frame payload contains a header block fragment
+   *   (Section 4.3). *)
+  | Continuation of Bigstringaf.t
+  | Unknown of int * Bigstringaf.t
+
+(* From RFC7540§4.1:
+ *   All frames begin with a fixed 9-octet header followed by a variable-length
+ *   payload. *)
+type t =
+  { frame_header : frame_header
+  ; frame_payload : frame_payload
+  }