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 gchar *
decode_quoted(const gchar *text, const gchar *end) {
    gchar *to = malloc(end - text + 1), *to_2 = to;
        if (!to) return NULL;
    while (*text && text < end) {
        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++;
        }
    }
    return to_2;
}

static gchar *
decode_base64(const gchar *data, const gchar *end) {
    unsigned short pattern = 0;
    int bits = 0;
    int delimiter = '=';
    gchar x;
    gchar *buffer = g_malloc((end - data) * 3);
    gchar *t = buffer;
    int Q = 0;

    if (!buffer) return NULL;

    while (*data != delimiter) {
        x = base64_rank[(unsigned char)(*data++)];
        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;
    return buffer;
}

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*
rfc2047_decode_word (const gchar *data, const gchar *into_what) 
{
    const char *charset = strstr(data, "=?"), *encoding, *text, *end;

    char *buffer, *b, *cooked_data;
    
    buffer = g_malloc(strlen(data) * 2);
    b = buffer;

    if (!charset) return strdup(data);
    charset+=2;

    encoding = strchr(charset, '?');
    if (!encoding) return strdup(data);
    encoding++;

    text = strchr(encoding, '?');
    if (!text) return strdup(data);
    text++;

    end = strstr(text, "?=");
    if (!end) return strdup(data);

    b[0] = 0;

    if (toupper(*encoding)=='Q')
        cooked_data = decode_quoted(text, end);
    else if (toupper(*encoding)=='B')
        cooked_data = decode_base64(text, end);
    else
        return g_strdup(data);

    {
        char *c = strchr(charset, '?');
        char *q = g_malloc(c - charset + 1);
        char *cook_2 = cooked_data;
        int cook_len = strlen(cook_2);
        int b_len = 4096;
        iconv_t i;
        strncpy(q, charset, c - charset);
        q[c - charset] = 0;
        i = unicode_iconv_open(into_what, q);
        if (!i) {
            g_free(q);
            return g_strdup(buffer);
        }
        unicode_iconv(i, &cook_2, &cook_len, &b, &b_len);
        unicode_iconv_close(i);
        *b = 0;
    }

    return g_strdup(buffer);
}

static gchar *
find_end_of_encoded_word(const gchar *data) {
    /* We can't just search for ?=,
           because of the case :
           "=?charset?q?=ff?=" :( */
    if (!data) return NULL;
    data = strstr(data, "=?");
    if (!data) return NULL;
    data = strchr(data+2, '?');
    if (!data) return NULL;
    data = strchr(data+1, '?');
    if (!data) return NULL;
    data = strstr(data+1, "?=");
    if (!data) return NULL;
    return data + 2;
}

gchar *
gmime_rfc2047_decode (const gchar *data, const gchar *into_what) 
{
    char *buffer = malloc(strlen(data) * 4), *b = buffer;

    int was_encoded_word = 0;

    build_base64_rank_table ();

    while (data && *data) {
        char *word_start = strstr(data, "=?"), *decoded;
        if (!word_start) {
            strcpy(b, data);
            b[strlen(data)] = 0;
            return buffer;
        }
        if (word_start != data) {

            if (strspn(data, " \t\n\r") != (word_start - data)) {
                strncpy(b, data, word_start - data);
                b += word_start - data;
                *b = 0;
            }
        }
        decoded = rfc2047_decode_word(word_start, into_what);
        strcpy(b, decoded);
        b += strlen(decoded);
        *b = 0;
        g_free(decoded);

        data = find_end_of_encoded_word(data);
    }

    *b = 0;
    return buffer;
}

gchar 
*gmime_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", (unsigned char)*s);
            } else {
                b += sprintf (b, "%c", *s);
            }
            s++;
        }
        b += sprintf (b, "?=");
    }
    
    *b = 0;
    
    return g_strdup (buffer);
}