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/* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8 -*- */
/*
 * Copyright (C) 2002 Ximian, Inc.
 *
 * Authors: Jeffrey Stedfast <fejj@ximian.com>
 *      Michael Zucchi <notzed@ximian.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of version 2 of the GNU General Public
 * License as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public
 * License along with this program; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */

/* canonicalisation filter, used for secure mime incoming and outgoing */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <string.h>
#include <ctype.h>

#include "camel-mime-filter-canon.h"

static void filter (CamelMimeFilter *f, char *in, size_t len, size_t prespace,
            char **out, size_t *outlen, size_t *outprespace);
static void complete (CamelMimeFilter *f, char *in, size_t len,
              size_t prespace, char **out, size_t *outlen,
              size_t *outprespace);
static void reset (CamelMimeFilter *f);


static void
camel_mime_filter_canon_class_init (CamelMimeFilterCanonClass *klass)
{
    CamelMimeFilterClass *mime_filter_class = (CamelMimeFilterClass *) klass;
    
    mime_filter_class->filter = filter;
    mime_filter_class->complete = complete;
    mime_filter_class->reset = reset;
}

CamelType
camel_mime_filter_canon_get_type (void)
{
    static CamelType type = CAMEL_INVALID_TYPE;
    
    if (type == CAMEL_INVALID_TYPE) {
        type = camel_type_register (camel_mime_filter_get_type(), "CamelMimeFilterCanon",
                        sizeof (CamelMimeFilterCanon),
                        sizeof (CamelMimeFilterCanonClass),
                        (CamelObjectClassInitFunc) camel_mime_filter_canon_class_init,
                        NULL,
                        NULL,
                        NULL);
    }
    
    return type;
}

static void
filter(CamelMimeFilter *f, char *in, size_t len, size_t prespace, char **out, size_t *outlen, size_t *outprespace)
{
    register unsigned char *inptr, c;
    const unsigned char *inend, *start;
    char *starto;
    register char *o;
    int lf = 0;
    guint32 flags;

    flags = ((CamelMimeFilterCanon *)f)->flags;

    /* first, work out how much space we need */
    inptr = in;
    inend = in+len;
    while (inptr < inend)
        if (*inptr++ == '\n')
            lf++;

    /* worst case, extra 3 chars per line
       "From \n" -> "=46rom \r\n"
       We add 1 extra incase we're called from complete, when we didn't end in \n */

    camel_mime_filter_set_size(f, len+lf*3+4, FALSE);

    o = f->outbuf;
    inptr = in;
    start = inptr;
    starto = o;
    while (inptr < inend) {
        /* first, check start of line, we always start at the start of the line */
        c = *inptr;
        if (flags & CAMEL_MIME_FILTER_CANON_FROM && c == 'F') {
            inptr++;
            if (inptr < inend-4) {
                if (strncmp(inptr, "rom ", 4) == 0) {
                    *o++ = '=';
                    *o++ = '4';
                    *o++ = '6';
                } else
                    *o++ = 'F';
                *o++ = *inptr++;
                *o++ = *inptr++;
                *o++ = *inptr++;
                *o++ = *inptr++;
            } else {
                break;
            }
        }

        /* now scan for end of line */
        while (inptr < inend) {
            c = *inptr++;
            if (c == '\n') {
                /* check to strip trailing space */
                if (flags & CAMEL_MIME_FILTER_CANON_STRIP) {
                    while (o>starto && (o[-1] == ' ' || o[-1] == '\t' || o[-1]=='\r'))
                        o--;
                }
                /* check end of line canonicalisation */
                if (o>starto) {
                    if (flags & CAMEL_MIME_FILTER_CANON_CRLF) {
                        if (o[-1] != '\r')
                            *o++ = '\r';
                    } else {
                        if (o[-1] == '\r')
                            o--;
                    }
                } else if (flags & CAMEL_MIME_FILTER_CANON_CRLF) {
                    /* empty line */
                    *o++ = '\r';
                }
                
                *o++ = c;
                start = inptr;
                starto = o;
                break;
            } else
                *o++ = c;
        }
    }

    /* TODO: We should probably track if we end somewhere in the middle of a line,
       otherwise we potentially backup a full line, which could be large */

    /* we got to the end of the data without finding anything, backup to start and re-process next time around */
    camel_mime_filter_backup(f, start, inend - start);

    *out = f->outbuf;
    *outlen = starto - f->outbuf;
    *outprespace = f->outpre;
}

static void 
complete(CamelMimeFilter *f, char *in, size_t len, size_t prespace, char **out, size_t *outlen, size_t *outprespace)
{
    unsigned char *inptr, *inend;
    char *o, *starto;
    guint32 flags;

    if (len)
        filter(f, in, len, prespace, out, outlen, outprespace);

    /* the data didn't contain an eol or was too short for "From ", we only need to check for "From" and add an eol */
    if (f->backlen) {
        inptr = (unsigned char *)f->backbuf;
        inend = (unsigned char *)f->backbuf + f->backlen;
        starto = o = *out + *outlen;
        flags = ((CamelMimeFilterCanon *)f)->flags;

        /* Check any embedded "From " */
        if (f->backlen >= 5
            && (flags & CAMEL_MIME_FILTER_CANON_FROM)
            && strcmp(inptr, "From ") == 0) {
            strcpy(o, "=46rom ");
            o += 7;
            inptr += 5;
        }

        /* copy the rest of it */
        while (inptr < inend)
            *o++ = *inptr++;
        
        /* check to strip trailing space */
        if (flags & CAMEL_MIME_FILTER_CANON_STRIP) {
            while (o>starto && (o[-1] == ' ' || o[-1] == '\t' || o[-1]=='\r'))
                o--;
        }
        
#if 0
        /* Note: #if 0'd out because we do not want to add a
         * \r\n for PGP/MIME verification if it isn't there in
         * the original content stream */
        
        /* check end of line canonicalisation */
        if (o>starto) {
            if (flags & CAMEL_MIME_FILTER_CANON_CRLF) {
                if (o[-1] != '\r')
                    *o++ = '\r';
            } else {
                if (o[-1] == '\r')
                    o--;
            }
        }
        
        /* and always finish with an eol */
        *o++ = '\n';
#endif
        
        *outlen = o - *out;
        
        f->backlen = 0;
    }
}

static void
reset (CamelMimeFilter *f)
{
    /* no-op */
}

CamelMimeFilter *
camel_mime_filter_canon_new(guint32 flags)
{
    CamelMimeFilterCanon *chomp = CAMEL_MIME_FILTER_CANON (camel_object_new (CAMEL_MIME_FILTER_CANON_TYPE));

    chomp->flags = flags;

    return (CamelMimeFilter *) chomp;
}