# Libwww MIME Parsers

    /*
    **	(c) COPYRIGHT MIT 1995.
    **	Please first read the full copyright statement in the file COPYRIGH.
    */

The MIME parser stream presents a MIME document with a header and possibly a footer. It recursively invokes the format manager to handle embedded formats like MIME multipart. As well as stripping off and parsing the headers, the MIME parser has to parse any weird MIME encodings it may meet within the body parts of messages, and must deal with multipart messages (see HTBound.h).

This module is implemented to the level necessary for operation with WWW, but is not currently complete for any arbitrary MIME message.

This module is implemented by HTMIME.c, and it is a part of the W3C Sample Code Library.

    #ifndef HTMIME_H
    #define HTMIME_H

    #include "HTStream.h"
    #include "HTFormat.h"

## How to Deal with Unknown Data

When the MIME parser can't find a target stream, for example because the media type is unknown, or it has a content encoding or transfer encoding that it doesn't know about then it has to get rid of the data in some other fashion, for example by dumping it to local disk (but it could also be dumping it to a black hole). The following two functions allow you to set and get the stream to use in this situation. By default, libwww provides an implementation of a save stream as HTSaveLocally which you may want to use - this is for example used by the current profiles.

    extern void HTMIME_setSaveStream (HTConverter * save_stream);
    extern HTConverter * HTMIME_saveStream (void);

## MIME Parse Stream

This stream parses a complete MIME message and if a media type header is found then the stream stack is called to create the nest stream instance in the stream pipe. Any piece of the MIME body is pumped right through the stream.

    extern HTConverter HTMIMEConvert;

## MIME Header ONLY Parse Stream

This stream parses a complete MIME header and then returnes `HT_LOADED`. It does not set up any streams and resting data stays in the buffer. This can be used if you only want to parse the headers before you decide what to do next. This is for example the case with HTTP HEAD requests.

    extern HTConverter HTMIMEHeader;

## MIME Footer ONLY Parse Stream

Parse only a footer, for example after a chunked encoding.

    extern HTConverter HTMIMEFooter;

## HTTP 100 Continue Parse Stream

The 100 continue status codes can come at any time - we take them and put the data down a temporary stream. When the 100 continue message has been parsed, the stream returns `HT_CONTINUE`

    extern HTConverter HTMIMEContinue;

## HTTP 101 Switching Protocol Parse Stream

The 101 Switching Protocol status code indicates that the rest of the stream is using another format, protocol, what ever. The result is the same - we are done parsing here and must leave the rest to the next stream which hopefully knows more about how to parse the rest of the stream. The stream stack is called to look for a stream registered for handling `WWW_MIME_UPGRADE`. This steam should return `HT_LOADED` when it is done, `HT_ERROR` if an error occurred and `HT_OK` as long as it just reads more data.

    extern HTConverter HTMIMEUpgrade;

## HTTP 206 Partial Data MIME Parse Stream

In case we sent a Range conditional GET we may get back a 206 Partial Response. This response must be appended to the already existing cache entry before presented to the user. That is, first we load the cached object and pump it down the pipe and then the new data follows. Only the latter part gets appended to the cache, of course.

    extern HTConverter HTMIMEPartial;

    #endif