package pecu

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  1. Decode
  2. Encode
package pecu
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Pecu, decoder/encoder of quoted-printable flow.

A quoted-printable flow, is a rich text encoding used by emails to safely transmit a text even if it use some bytes which can not be encoded into 7 bits. It is described by RFC2045 as a possible Content-Transfer-Encoding of the email's contents. This library wants to provide a non-blocking encoder/decoder to this such format. quoted-printable does not imply any encoding. A latin1i can be used or UTF-8. This such information is available into the Content-type value.

Decode

type decoder

The type for decoders.

type src = [
  1. | `Manual
  2. | `Channel of Stdlib.in_channel
  3. | `String of string
]

The type for input sources. With a `Manual source the client must provide input with src.

type decode = [
  1. | `Await
  2. | `End
  3. | `Data of string
  4. | `Line of string
  5. | `Malformed of string
]
val src : decoder -> Stdlib.Bytes.t -> int -> int -> unit

src d s j l provides d with l bytes to read, starting at j in s. This byte range is read by calls to decode with d until `Await is returned. To signal the end of input, call the function with l = 0.

val decoder : src -> decoder

decoder src is a decoder that inputs from src.

val decode : decoder -> decode

decode d is:

  • `Await if d has a `Manual input source and awaits for more input. The client must use src to provide it.
  • `End if the end of input was reached.
  • `Malformed bytes if the bytes sequence is malformed according to the decoded quoted-printable encoding scheme. If you are interested in a best-effort decoding you can still continue to decode after an error until the decode synchronizes again on valid bytes.
  • `Data data if a data sequence value was decoded.
  • `Line line if a line sequence value plus a line-break was decoded.

Note. Repeated invocation always eventually returns `End, even in case of errors.

val decoder_byte_count : decoder -> int

decoder_byte_count d is the number of characters already decoded on d (included malformed ones). This is the last decode's end output offset counting from beginning of the stream.

val decoder_src : decoder -> src

decoder_src d is d's input source.

val decoder_dangerous : decoder -> bool

decoder_dangerous d returns true if encoded input does not respect the 80-columns rule. In this case, internal buffers can grow automatically. If you are interested in a best-effort decoding you can still continue to decode even if decoder_dangerous d returns true. However, it could be an attack entry point in a server-context.

Encode

type dst = [
  1. | `Channel of Stdlib.out_channel
  2. | `Buffer of Stdlib.Buffer.t
  3. | `Manual
]

The type for output destinations. With a `Manual destination the client must provide output storage with dst.

type encode = [
  1. | `Await
  2. | `End
  3. | `Char of char
  4. | `Line_break
]
type encoder

The type for Quoted-Printable encoder.

val encoder : dst -> encoder

encoder dst is an encoder for quoted-printable that outputs to dst.

val encode : encoder -> encode -> [ `Ok | `Partial ]

encode e v: is

  • `Partial iff e has a `Manual destination and needs more output storage. The client must use dst to provide a new buffer and then call encode with `Await until `Ok is returned.
  • `Ok when the encoder is ready to encode a new `Char, `Line_break or `End

For `Manual destination, encoding `End always return `Partial, the client should continue as usual with `Await until `Ok is returned at which point dst_rem encoder is guaranteed to be the sode of the last provided buffer (i.e. nothing was written).

Raises. Invalid_argument if a `Char, `Line_break or `End is encoded after a `Partial encode.

val encoder_dst : encoder -> dst

encoder_dst encoder is encoder's output destination.

val dst : encoder -> Stdlib.Bytes.t -> int -> int -> unit

dst e s j l provides e with l bytes to write, starting at j in s. This byte range is written by calls to encode with e until `Partial is returned. Use dst_rem to know the remaining number of non-written free bytes in s.

val dst_rem : encoder -> int

dst_rem e is the remaining number of non-written, free bytes in the last buffer provided with dst.

module Inline : sig ... end