module Netmime:sig..end
Contents
The tutorial has been moved to
Netmime_tut.typestore =[ `File of string | `Memory ]
`Memory
 means in-memory, `File name means in the file name. The body
 is stored in decoded form (i.e. without transfer encoding).exception Immutable of string
mime_header_ro, and mime_body_ro),
 and after that the full class type including write access is defined
 (mime_header, and mime_body).
The idea is that you can write functions that take an ro value as input to indicate that they do not modify the value. For example:
 let number_of_fields (h:#mime_header_ro) =
   List.length (h#fields) 
 This function accepts both mime_header, and mime_header_ro values as
 input, but the typing ensures that the function cannot mutate anything.
 There is another way to ensure that a header or body is not modified.
 The read-only flag can be set when creating the object, and this flag
 causes that all trials to modify the value will raise the exception
 Immutable. Of course, such trials of mutation are only detected at
 run-time.
 The advantage of the read-only flag is that it even works if 
 mutation depends on a condition, but it can be ensured that this
 condition is never true. Furthermore, typing is much simpler (getting
 subtyping correct can be annoying).
class type mime_header_ro =object..end
class type mime_header =object..end
class type mime_body_ro =object..end
class type mime_body =object..end
(mime_header, mime_body) as simple MIME
 message with one header and one body. Of course, this simple representation
 does not support multi-part messages (attachments). For that reason,
 the complex_mime_message was invented: The body can be further
 structured as a sequence of parts that are complex messages themselves.
For example, a mail message with an attachment is usually represented as
 (mail_header, `Parts [ (main_header, `Body main_body);
                        (att_header, `Body att_body) ] ) 
 Here, mail_header is the real header of the mail message.
 main_header is the header of the main message, usually
 only containing the content type of main_body, the body
 of the main message. The attachment has also its own 
 att_header, again usually only containing the content type,
 and the data of the attachment can be found in att_body.
 Nowadays, mails have often even a more complicated structure
 with `Parts containing nested `Parts. As complex_mime_message
 is recursive, any kind of nesting can be easily represented.
typecomplex_mime_message =mime_header * complex_mime_body
typecomplex_mime_body =[ `Body of mime_body | `Parts of complex_mime_message list ]
typecomplex_mime_message_ro =mime_header_ro * complex_mime_body_ro
typecomplex_mime_body_ro =[ `Body of mime_body_ro
| `Parts of complex_mime_message_ro list ]
`Parts [], i.e. `Parts together with an empty list, is 
 considered as illegal. Such a value cannot be transformed into
 printable text.typemime_message =mime_header * [ `Body of mime_body ]
typemime_message_ro =mime_header_ro * [ `Body of mime_body_ro ]
class basic_mime_header :?ro:bool -> (string * string) list ->mime_header
mime_header.
class memory_mime_body :?ro:bool -> string ->mime_body
mime_body where the value is stored
 in-memory.
class file_mime_body :?ro:bool -> ?fin:bool -> string ->mime_body
mime_body where the value is stored
 in an external file.
val read_mime_header : ?unfold:bool ->
       ?strip:bool -> ?ro:bool -> Netstream.in_obj_stream -> mime_headerbasic_mime_header.
 After returning, the stream is advanced to the byte following the 
 empty line terminating the header.
Example: To read the header at the beginning of the file "f", use:
 
 let ch = new Netchannels.input_channel (open_in "f") in
 let stream = new Netstream.input_stream ch in
 let h = read_mime_header stream in
 ...
 stream#close_in();    (* no need to close ch *)
 
 Note that although the stream position after parsing is exactly 
 known, the position of ch cannot be predicted.
unfold : whether linefeeds are replaced by spaces in the values of the
   header fields (Note: defaults to false here in contrast to
   Mimestring.scan_header!)strip : whether whitespace at the beginning and at the end of the 
   header fields is strippedro : whether the returned header is read-only (default: false)h into the channel ch, use
  Mimestring.write_header ch h#fields 
 Link: Mimestring.write_header
typemultipart_style =[ `Deep | `Flat | `None ]
`None: Do not handle multipart messages specially. Multipart bodies
    are not further decoded, and returned as `Body b where b is
    the transfer-encoded text representation.`Flat: If the top-level message is a multipart message, the parts
    are separated and returned as list. If the parts are again multipart
    messages, these inner multipart messages are not furher decoded 
    and returned as `Body b.`Deep: Multipart messages are recursively decoded and returned as
    tree structure.complex_mime_message structure
 is created for a parsed MIME message. `None means that no parts
 are decoded, and messages have always only a simple `Body b,
 even if b is in reality a multi-part body. With `Flat, the
 top-level multi-part bodies are decoded (if found), and messages
 can have a structured `Parts [_, `Body b1; _, `Body b1; ...]
 body. Finally, `Deep allows that inner multi-part bodies are
 recursively decoded, and messages can have an arbitrarily complex
 form.val decode_mime_body : #mime_header_ro ->
       Netchannels.out_obj_channel -> Netchannels.out_obj_channellet ch' = decode_mime_body hdr ch:
 According to the value of the Content-transfer-encoding header field
 in hdr the encoded MIME body written to ch' is decoded and transferred
 to ch.
Handles 7bit, 8bit, binary, quoted-printable, base64.
Example: The file "f" contains base64-encoded data, and is to be decoded and to be stored in "g":
 
 let ch_f = new Netchannels.input_channel (open_in "f") in
 let ch_g = new Netchannels.output_channel (open_out "g") in
 let hdr = new basic_mime_header ["content-transfer-encoding", "base64" ] in
 let ch = decode_mime_body hdr ch_g in
 ch # output_channel ch_f;
 ch # close_out();
 ch_g # close_out();
 ch_f # close_in();
 
 Note: This function is internally used by read_mime_message to
 decode bodies. There is usually no need to call it directly.
val storage : ?ro:bool ->
       ?fin:bool -> store -> mime_body * Netchannels.out_obj_channelstore.
 This function can be used to build the storage_style argument 
 of the class read_mime_message (below). For example, this is
 useful to store large attachments in external files, as in:
 
 let storage_style hdr = 
   let filename = hdr ... (* extract from hdr *) in
   storage (`File filename)
 
ro : whether the returned mime_bodies are read-only or not. Note that
   it is always possible to write into the body using the returned
   out_obj_channel regardless of the value of ~ro.
   Default: falsefin : whether to finalize bodies stored in files.
   Default: falseval read_mime_message : ?unfold:bool ->
       ?strip:bool ->
       ?ro:bool ->
       ?multipart_style:multipart_style ->
       ?storage_style:(mime_header ->
                       mime_body * Netchannels.out_obj_channel) ->
       Netstream.in_obj_stream -> complex_mime_message
 Multipart messages are decoded as specified by multipart_style (see
 above).
Message bodies with content-transfer-encodings of 7bit, 8bit, binary, base64, and quoted-printable can be processed. The bodies are stored without content-transfer-encoding (i.e. in decoded form), but the content-transfer-encoding header field is not removed from the header.
 The storage_style function determines where every message body is
 stored. The corresponding header of the body is passed to the function
 as argument; the result of the function is a pair of a new mime_body
 and an out_obj_channel writing into this body. You can create such a
 pair by calling storage (above).
 By default, the storage_style is storage ?ro `Memory for every header. 
 Here, the designator `Memory means that the body will be stored in an
 O'Caml string. The designator `File fn would mean that the body will be stored in the
 file fn. The file would be created if it did not yet exist, and
 it would be overwritten if it did already exist.
 Note that the storage_style function is called for every non-multipart
 body part.
Large message bodies (> maximum string length) are supported if the bodies are stored in files. The memory consumption is optimized for this case, and usually only a small constant amount of memory is needed.
Example:
Parse the MIME message stored in the file f:
 let m = read_mime_message 
           (new input_stream (new input_channel (open_in f)))
 
unfold : whether linefeeds are replaced by spaces in the values of the
   header fields (Note: defaults to false here in contrast to
   Mimestring.scan_header!)strip : whether whitespace at the beginning and at the end of the 
   header fields is strippedro : Whether the created MIME headers are read-only or not. Furthermore,
   the default storage_style uses this parameter for the MIME bodies, too.
   However, the MIME bodies may have a different read-only flag in general.val encode_mime_body : ?crlf:bool ->
       #mime_header_ro ->
       Netchannels.out_obj_channel -> Netchannels.out_obj_channellet ch' = encode_mime_body hdr ch:
 According to the value of the Content-transfer-encoding header field
 in hdr the unencoded MIME body written to ch' is encoded and transferred
 to ch.
Handles 7bit, 8bit, binary, quoted-printable, base64.
 For an example, see decode_mime_body which works in a similar way
 but performs decoding instead of encoding.
crlf : if set (this is by default the case) CR/LF will be used for
   end-of-line (eol) termination, if not set LF will be used. For 7bit, 8bit and
   binary encoding the existing eol delimiters are not rewritten, so this option
   has only an effect for quoted-printable and base64.val write_mime_message : ?wr_header:bool ->
       ?wr_body:bool ->
       ?nr:int ->
       ?ret_boundary:string Pervasives.ref ->
       ?crlf:bool ->
       Netchannels.out_obj_channel -> complex_mime_message -> unitThe function fails if multipart messages do not have a multipart content type field (i.e. the content type does not begin with "multipart"). If only the boundary parameter is missing, a good boundary parameter is added to the content type. "Good" means here that it is impossible that the boundary string occurs in the message body if the content-transfer-encoding is quoted-printable or base64, and that such an occurrence is very unlikely if the body is not encoded. If the whole content type field is missing, a "multipart/mixed" type with a boundary parameter is added to the printed header.
Note that already existing boundaries are used, no matter whether they are of good quality or not.
No other header fields are added, deleted or modified. The mentioned modifications are _not_ written back to the passed MIME message but only added to the generated message text.
It is possible in some cases that the boundary does not work (both the existing boundary, and the added boundary). This causes that a wrong and unparseable MIME message is written. In order to ensure a correct MIME message, it is recommended to parse the written text, and to compare the structure of the message trees. It is, however, very unlikely that a problem arises.
Note that if the passed message is a simple message like (_,`Body _), and if no content-transfer-encoding is set, the written message might not end with a linefeed character.
wr_header : If true, the outermost header is written. Inner headers
   of the message parts are written unless ~wr_body=false.wr_body : If true, the body of the whole message is written; if false,
   no body is written at all.nr : This argument sets the counter that is included in generated
   boundaries to a certain minimum value.ret_boundary : if passed, the boundary of the outermost multipart
   message is written to this reference. (Internally used.)crlf : if set (this is by default the case) CR/LF will be used for
   end-of-line (eol) termination, if not set LF will be used. The eol 
   separator is used for the header, the multipart framing, and for
   bodies encoded as quoted-printable or base64. Other eol separators are
   left untouched.