package protocol_version_header

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package protocol_version_header
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This library offers a lightweight way for applications protocols to version themselves. The more protocols that add themselves to Known_protocol, the nicer error messages we will get when connecting to a service while using the wrong protocol.

type t
include Core.Bin_prot.Binable.S with type t := t
include Bin_prot.Binable.S_only_functions with type t := t
val bin_size_t : t Bin_prot.Size.sizer
val bin_write_t : t Bin_prot.Write.writer
val bin_read_t : t Bin_prot.Read.reader
val __bin_read_t__ : (int -> t) Bin_prot.Read.reader

This function only needs implementation if t exposed to be a polymorphic variant. Despite what the type reads, this does *not* produce a function after reading; instead it takes the constructor tag (int) before reading and reads the rest of the variant t afterwards.

val bin_shape_t : Bin_prot.Shape.t
val bin_writer_t : t Bin_prot.Type_class.writer
val bin_reader_t : t Bin_prot.Type_class.reader
include Sexplib0.Sexpable.S with type t := t
val t_of_sexp : Sexplib0.Sexp.t -> t
val sexp_of_t : t -> Sexplib0.Sexp.t
val create_exn : protocol:Known_protocol.t -> supported_versions:int list -> t

create_exn ~protocol ~supported_version raises if List.length supported_versions >= 100

val negotiate : allow_legacy_peer:bool -> us:t -> peer:t -> int Core.Or_error.t

negotiate ~allow_legacy_peer ~us ~peer inspects the magic numbers of us and peer. If the magic numbers match, the highest shared version number is returned.

If allow_legacy_peer then the magic number of peer is assumed to be us if no magic number exists.

val contains_magic_prefix : protocol:Known_protocol.t -> bool Core.Bin_prot.Type_class.reader

contains_magic_prefix reads a bin_protted value of type t and returns a boolean saying whether this magic number was observed.

any_magic_prefix and any_magic_prefix_from_six_bytes read the magic number for one of the known protocols. They differ in how many bytes they read.

any_magic_prefix reads the entire Protocol_version_header.t and then checks if there's any magic prefix in there. The number of bytes in the bin_io representation of a Protocol_version_header.t is not fixed because it depends on the supported versions of the protocol.

any_magic_prefix_from_six_bytes reads exactly 6 bytes to check magic prefix.

any_magic_prefix_from_six_bytes_bin_size is 6: the number of bytes that any_magic_prefix_from_six_bytes reads.

val any_magic_prefix_from_six_bytes : Known_protocol.t option Core.Bin_prot.Type_class.reader

See any_magic_prefix

val any_magic_prefix_from_six_bytes_bin_size : int

See any_magic_prefix

module Known_protocol : sig ... end
module For_test : sig ... end