Module `Lber`

This library implements the subset of ber

exception Decoding_error of string
exception Encoding_error of string

type readbyte_error = | End_of_stream | Transport_error | Peek_error | Request_too_large | Not_implemented

exception Readbyte_error of readbyte_error

type readbyte = ?⁠peek:bool -> int -> string
type writebyte = char -> unit
type ber_class = | Universal | Application | Context_specific | Private
type ber_length = | Definite of int | Indefinite
type ber_val_header = { ber_class : ber_class; ber_primitive : bool; ber_tag : int; ber_length : ber_length; }

val readbyte_of_string : string -> readbyte: return a readbyte function for a string, currently not implemented

val readbyte_of_ber_element : ber_length -> readbyte -> readbyte

return a readbyte implementation which uses another readbyte, but allows setting a read boundry. Useful for constructing views of the octet stream which end at the end of a ber structure. This is essential for reading certian structures because length is only encoded in the toplevel in order to save space. Currently only implemented for definite lengths.

raises Readbyte_error: in the event of a an io error, or the end of file

val readbyte_of_fd : Unix.file_descr -> readbyte

a readbyte implementation which reads from an FD. It implements a peek buffer, so it can garentee that it will work with rb_of_ber_element, even with blocking fds.

raises Readbyte_error: in the event of a an io error, or the end of file

val readbyte_of_ssl : Ssl.socket -> readbyte

a readbyte implementation which reads from an SSL socket. It is otherwise the same as readbyte_of_fd.

raises Readbyte_error: in the event of a an io error, or the end of file

val decode_ber_header : ?⁠peek:bool -> readbyte -> ber_val_header: decoding and encoding of the ber header

val encode_ber_header : ber_val_header -> string
val read_contents : ?⁠peek:bool -> readbyte -> ber_length -> string: reads the contents octets

val decode_ber_bool : ?⁠peek:bool -> ?⁠cls:ber_class -> ?⁠tag:int -> ?⁠contents:string option -> readbyte -> bool: Encoding/Decoding of the boolean primative ASN.1 type. Encode function encodes a valid ber type, including the header and length octets.

val encode_ber_bool : ?⁠cls:ber_class -> ?⁠tag:int -> bool -> string
val decode_ber_int32 : ?⁠peek:bool -> ?⁠cls:ber_class -> ?⁠tag:int -> ?⁠contents:string option -> readbyte -> int32: Encoding/Decoding of the integer primative ASN.1 type. Note, in this library, integers are represented as 32 bit values. In ASN.1 there is no practical limit to the size of an integer, later on, this library may provide an encoder/decoder to Int64, and Bigints, however for now, this will have to do. Encode function encodes a valid ber type, including the header and length octets

val encode_ber_int32 : ?⁠cls:ber_class -> ?⁠tag:int -> int32 -> string
val decode_ber_enum : ?⁠peek:bool -> ?⁠cls:ber_class -> ?⁠tag:int -> ?⁠contents:string option -> readbyte -> int32: Encoding/Decoding of enum primative ASN.1 type. Enums are simply integers, the same drawbacks apply as for decode_ber_int32. Encode function encodes a valid ber type, including the header and length octets

val encode_ber_enum : ?⁠cls:ber_class -> ?⁠tag:int -> int32 -> string
val decode_ber_octetstring : ?⁠peek:bool -> ?⁠cls:ber_class -> ?⁠tag:int -> ?⁠contents:string option -> readbyte -> string: Encoding/Decoding of octetstring ASN.1 types. The Nested or "segmented" version of the octetstring encoding described in X.690 is not yet supported. Encode function encodes a valid ber type, including the header and length octets

val encode_ber_octetstring : ?⁠cls:ber_class -> ?⁠tag:int -> string -> string
val decode_ber_null : ?⁠peek:bool -> ?⁠cls:ber_class -> ?⁠tag:int -> ?⁠contents:string option -> readbyte -> unit: Encoding/Decoding of Null ASN.1 type. Almost useful as an assertion-type operation

val encode_ber_null : ?⁠cls:ber_class -> ?⁠tag:int -> unit -> string
val encode_berval_list : ?⁠buf:Stdlib.Buffer.t -> ('a -> string) -> 'a list -> string: this function is for encoding lists of bervals, a common case. you pass it a list of things to encode, and an encoding function, and it will apply the encoding function to each element in the list, storing the resulting encoding in a buffer (which you may either pass in or not)

val decode_berval_list : ?⁠lst:'a list -> (readbyte -> 'a) -> readbyte -> 'a list: this is the reverse of the above, it takes a readbyte structure, and returns a list of decoded elements, processed according to the decoder function you pass in. Note, that you MUST pass a readbyte structure built with readbyte_of_string, OR, your reabyte function must raise Stream.Failure when you reach the end of input. Otherwise this function will explode. That said, it is usually not practical to pass anything but a readbyte created by readbyte_of_string so this should not be a huge problem.