path: root/camel/gmime-rfc2047.c

/* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8 -*- */
/* gmime-rfc2047.c: implemention of RFC2047 */

/*
 * Copyright (C) 1999 Bertrand Guiheneuf <Bertrand.Guiheneuf@inria.fr> .
 * 
 * This program is free software; you can redistribute it and/or 
 * modify it under the terms of the GNU General Public License as 
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 *
 * 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
 *
 */

/* 
 * Authors:  Robert Brady <rwb197@ecs.soton.ac.uk>
 */

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

#include "gmime-rfc2047.h"

#define NOT_RANKED -1

/* This should be changed ASAP to use the base64 code Miguel comitted */

const char *base64_alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

static unsigned char base64_rank[256];
static int base64_rank_table_built;
static void build_base64_rank_table (void);

static int 
hexval (gchar c) {
    if (isdigit (c)) return c-'0';
    c = tolower (c);
    return c - 'a' + 10;
}

static void 
decode_quoted (const gchar *text, gchar *to) 
{
    while (*text) {
        if (*text == '=') {
            gchar a = hexval (text[1]);
            gchar b = hexval (text[2]);
            int c = (a << 4) + b;
            *to = c;
            to++;
            text+=3;
        } else if (*text == '_') {
            *to = ' ';
            to++;
            text++;
        } else {
            *to = *text;
            to++;
            text++;
        }
    }
    *to = 0;
}

static void 
decode_base64 (const gchar *what, gchar *where) 
{
    unsigned short pattern = 0;
    int bits = 0;
    int delimiter = '=';
    gchar x;
    gchar *t = where;
    int Q = 0;
    while (*what != delimiter) {
        x = base64_rank[(unsigned char)(*what++)];
        if (x == NOT_RANKED)
            continue;
        pattern <<= 6;
        pattern |= x;
        bits += 6;
        if (bits >= 8) {
            x = (pattern >> (bits - 8)) & 0xff;
            *t++ = x;
            Q++;
            bits -= 8;
        }
    }
    *t = 0;
}

static void
build_base64_rank_table (void)
{
    int i;
    
    if (!base64_rank_table_built) {
        for (i = 0; i < 256; i++)
            base64_rank[i] = NOT_RANKED;
        for (i = 0; i < 64; i++)
            base64_rank[(int) base64_alphabet[i]] = i;
        base64_rank_table_built = 1;
    }
}

gchar 
*gmime_rfc2047_decode (const gchar *data, const gchar *into_what) 
{
    gchar buffer[4096] /* FIXME : constant sized buffer */, *b = buffer;
    
    build_base64_rank_table ();
    
    while (*data) {
        
        /* If we encounter an error we just break out of the loop and copy the rest
         * of the text as-is */
        
        if (*data=='=') {
            data++;
            if (*data=='?') {
                gchar *charset, *encoding, *text, *end;
                gchar dc[4096];
                charset = data+1;
                encoding = strchr(charset, '?');
                
                if (!encoding) break;
                encoding++;
                text = strchr (encoding, '?');
                if (!text) break;
                text++;
                end = strstr (text, "?=");
                if (!end) break;
                end++;
                
                *(encoding-1)=0;
                *(text-1)=0;
                *(end-1)=0;
                
                if (strcasecmp (encoding, "q") == 0) {
                    decode_quoted(text, dc);
                } else if (strcasecmp (encoding, "b") == 0) {
                    decode_base64 (text, dc);
                } else {
                    /* What to do here? */
                    break;
                }
                
                {
                    int f;
                    iconv_t i;
                    const gchar *d2 = dc;
                    int l = strlen (d2), l2 = 4000;
                    
                    i = unicode_iconv_open (into_what, charset);
                    if (!i) 
                        break;
                    
                    unicode_iconv (i, &d2, &l, &b, &l2);
                    
                    unicode_iconv_close (i);
                    data = end;
                }
            }
        } else {
            *b = *data;
            b++;
        }
        
        data++;
        
    }
    
    while (*data) {
        *b = *data;
        b++;
        data++;
    }
    
    *b = 0;
    
    return g_strdup (buffer);
}

gchar 
*rfc2047_encode (const gchar *string, const gchar *charset) 
{
    gchar buffer[4096] /* FIXME : constant sized buffer */;
    gchar *b = buffer;
    const gchar *s = string;
    int not_ascii = 0, not_latin1 = 0;
    while (*s) {
        if (*s <= 20 || *s >= 0x7f || *s == '=') { not_ascii = 1; }
        s++;
    }
    
    if (!not_ascii) {
        b += sprintf (b, "%s", string);
    }
    
    else {
        b += sprintf (b, "=?%s?Q?", charset);
        s = string;
        while (*s) {
            if (*s == ' ') b += sprintf (b, "_");
            else if (*s < 0x20 || *s >= 0x7f || *s == '=' || *s == '?' || *s == '_') {
                b += sprintf (b, "=%2x", *s);
            } else {
                b += sprintf (b, "%c", *s);
            }
            s++;
        }
        b += sprintf (b, "?=");
    }
    
    *b = 0;
    
    return g_strdup (buffer);
}