path: root/camel/camel-stream-b64.c

/* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8 -*- */


/* 
 *
 * Author : 
 *  Bertrand Guiheneuf <bertrand@helixcode.com>
 *
 * Copyright 1999, 2000 HelixCode (http://www.helixcode.com) .
 *
 * 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
 */
#include <config.h>
#include "camel-stream-b64.h"

#define BSIZE 512



static CamelStreamClass *parent_class = NULL;

static guchar char_to_six_bits [256] = {
    128, 128, 128, 128, 128, 128, 128, 128, /*   0 .. 7   */
    128, 128, 128, 128, 128, 128, 128, 128, /*   8 .. 15  */
    128, 128, 128, 128, 128, 128, 128, 128, /*  16 .. 23  */
    128, 128, 128, 128, 128, 128, 128, 128, /*  24 .. 31  */
    128, 128, 128, 128, 128, 128, 128, 128, /*  32 .. 39  */
    128, 128, 128,  62, 128, 128, 128,  63, /*  40 .. 47  */
     52,  53,  54,  55,  56,  57,  58,  59, /*  48 .. 55  */
     60,  61, 128, 128, 128,  64, 128, 128, /*  56 .. 63  */
    128,   0,   1,   2,   3,   4,   5,   6, /*  64 .. 71  */
      7,   8,   9,  10,  11,  12,  13,  14, /*  72 .. 79  */
     15,  16,  17,  18,  19,  20,  21,  22, /*  80 .. 87  */
     23,  24,  25, 128, 128, 128, 128, 128, /*  88 .. 95  */
    128,  26,  27,  28,  29,  30,  31,  32, /*  96 .. 103 */
     33,  34,  35,  36,  37,  38,  39,  40, /* 104 .. 111 */
     41,  42,  43,  44,  45,  46,  47,  48, /* 112 .. 119 */
     49,  50,  51, 128, 128, 128, 128, 128, /* 120 .. 127 */
    128, 128, 128, 128, 128, 128, 128, 128, /* 128 .. 135 */
    128, 128, 128, 128, 128, 128, 128, 128, /* 136 .. 143 */
    128, 128, 128, 128, 128, 128, 128, 128, /* 144 .. 151 */
    128, 128, 128, 128, 128, 128, 128, 128, /* 152 .. 159 */
    128, 128, 128, 128, 128, 128, 128, 128, /* 160 .. 167 */
    128, 128, 128, 128, 128, 128, 128, 128, /* 168 .. 175 */
    128, 128, 128, 128, 128, 128, 128, 128, /* 176 .. 183 */
    128, 128, 128, 128, 128, 128, 128, 128, /* 184 .. 191 */
    128, 128, 128, 128, 128, 128, 128, 128, /* 192 .. 199 */
    128, 128, 128, 128, 128, 128, 128, 128, /* 200 .. 207 */
    128, 128, 128, 128, 128, 128, 128, 128, /* 208 .. 215 */
    128, 128, 128, 128, 128, 128, 128, 128, /* 216 .. 223 */
    128, 128, 128, 128, 128, 128, 128, 128, /* 224 .. 231 */
    128, 128, 128, 128, 128, 128, 128, 128, /* 232 .. 239 */
    128, 128, 128, 128, 128, 128, 128, 128, /* 240 .. 247 */
    128, 128, 128, 128, 128, 128, 128, 128  /* 248 .. 255 */
};


static gchar six_bits_to_char[65] = 
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";

/* Returns the class for a CamelStreamB64 */
#define CSB64_CLASS(so) CAMEL_STREAM_B64_CLASS (GTK_OBJECT(so)->klass)

static void           my_init_with_input_stream         (CamelStreamB64 *stream_b64, 
                             CamelStream *input_stream);

static gint           my_read                           (CamelStream *stream, 
                             gchar *buffer, 
                             gint n);

static void           my_reset                          (CamelStream *stream);

static gint           my_read_decode                    (CamelStream *stream, 
                             gchar *buffer, 
                             gint n);
static gint           my_read_encode                    (CamelStream *stream, 
                             gchar *buffer, 
                             gint n);
static gboolean       my_eos                            (CamelStream *stream);

static void
camel_stream_b64_class_init (CamelStreamB64Class *camel_stream_b64_class)
{
    CamelStreamClass *camel_stream_class = CAMEL_STREAM_CLASS (camel_stream_b64_class);
    
    
    parent_class = gtk_type_class (camel_stream_get_type ());
    
    /* virtual method definition */
    camel_stream_b64_class->init_with_input_stream = my_init_with_input_stream;
    
    
    /* virtual method overload */
    camel_stream_class->read     = my_read;
    camel_stream_class->eos      = my_eos; 
    camel_stream_class->reset    = my_reset; 
    
    /* signal definition */
    
}

GtkType
camel_stream_b64_get_type (void)
{
    static GtkType camel_stream_b64_type = 0;
    
    if (!camel_stream_b64_type) {
        GtkTypeInfo camel_stream_b64_info = 
        {
            "CamelStreamB64",
            sizeof (CamelStreamB64),
            sizeof (CamelStreamB64Class),
            (GtkClassInitFunc) camel_stream_b64_class_init,
            (GtkObjectInitFunc) NULL,
                /* reserved_1 */ NULL,
                /* reserved_2 */ NULL,
            (GtkClassInitFunc) NULL,
        };
        
        camel_stream_b64_type = gtk_type_unique (camel_stream_get_type (), &camel_stream_b64_info);
    }
    
    return camel_stream_b64_type;
}


static void 
my_reemit_available_signal (CamelStream *parent_stream, gpointer user_data)
{
    gtk_signal_emit_by_name (GTK_OBJECT (user_data), "data_available");
}

static void           
my_init_with_input_stream (CamelStreamB64 *stream_b64, 
               CamelStream *input_stream)
{
    g_assert (stream_b64);
    g_assert (input_stream);

    
    
    /* by default, the stream is in decode mode */  
    stream_b64->mode = CAMEL_STREAM_B64_DECODER;
    
    stream_b64->eos = FALSE;
    stream_b64->status.decode_status.keep = 0;
    stream_b64->status.decode_status.state = 0;
        
    stream_b64->input_stream = input_stream;
    
    gtk_object_ref (GTK_OBJECT (input_stream));
    
    /* 
     *  connect to the parent stream "data_available"
     *  stream so that we can reemit the signal on the 
     *  seekable substream in case some data would 
     *  be available for us 
     */
    gtk_signal_connect (GTK_OBJECT (input_stream),
                "data_available", 
                my_reemit_available_signal,
                stream_b64);
    
    
    /* bootstrapping signal */
    gtk_signal_emit_by_name (GTK_OBJECT (stream_b64), "data_available");
    
    
}



CamelStream *
camel_stream_b64_new_with_input_stream (CamelStream *input_stream)
{
    CamelStreamB64 *stream_b64;
    
    stream_b64 = gtk_type_new (camel_stream_b64_get_type ());
    CSB64_CLASS (stream_b64)->init_with_input_stream (stream_b64, input_stream);

    return CAMEL_STREAM (stream_b64);
}




void       
camel_stream_b64_set_mode (CamelStreamB64 *stream_b64,
               CamelStreamB64Mode mode)
{
    g_assert (stream_b64);

    stream_b64->mode = mode;

    if (mode == CAMEL_STREAM_B64_DECODER) {
        stream_b64->status.decode_status.keep = 0;
        stream_b64->status.decode_status.state = 0;
    } else {
        stream_b64->status.encode_status.keep = 0;
        stream_b64->status.encode_status.state = 0;
        stream_b64->status.encode_status.end_state = 0;
    }

}




static gint 
my_read (CamelStream *stream, 
     gchar *buffer, 
     gint n)
{
    CamelStreamB64 *stream_b64 = CAMEL_STREAM_B64 (stream);
    
    g_assert (stream);
        
    
    if (stream_b64->mode == CAMEL_STREAM_B64_DECODER)
        return my_read_decode (stream, buffer, n);
    else 
        return my_read_encode (stream, buffer, n);
}



static gint 
my_read_decode (CamelStream *stream, 
        gchar *buffer, 
        gint n)
{
    CamelStreamB64 *stream_b64 = CAMEL_STREAM_B64 (stream);
    CamelStream64DecodeStatus *status;
    CamelStream    *input_stream;
    guchar six_bits_value;
    gint nb_read_in_input;
    guchar c;
    gint j = 0;
    
    g_assert (stream);
    input_stream = stream_b64->input_stream;
    
    g_assert (input_stream);
    status = &(stream_b64->status.decode_status);
    

    nb_read_in_input = camel_stream_read (input_stream, &c, 1);
    
    while ((nb_read_in_input >0 ) && (j<n)) {
        
        six_bits_value = char_to_six_bits[c];
        
        /* if we encounter an '=' we can assume the end of the stream 
           has been found */
        if (six_bits_value == 64) {
            stream_b64->eos = TRUE;
            status->keep = 0;
            
            break;
        }
        
        /* test if we must ignore the character */
        if (six_bits_value != 128) {
            six_bits_value = six_bits_value & 0x3f;

            switch (status->state){
            case 0:
                status->keep =  six_bits_value << 2;
                
                break;
            case 1:
                buffer [j++] = status->keep | (six_bits_value >> 4);
                status->keep = (six_bits_value & 0xf) << 4;
                break;
            case 2:
                buffer [j++] = status->keep | (six_bits_value >> 2);
                status->keep = (six_bits_value & 0x3) << 6;
                break;
            case 3:
                buffer [j++] = status->keep | six_bits_value;
                status->keep = 0;
                break;
            }
            
            status->state = (status->state + 1) % 4;
            
        }
        
        if (j<n) nb_read_in_input = camel_stream_read (input_stream, &c, 1);
        
    }
    
    return j;
    
}


static gint 
my_read_encode (CamelStream *stream, 
        gchar *buffer, 
        gint n)
{
    CamelStreamB64 *stream_b64 = CAMEL_STREAM_B64 (stream);
    CamelStream64EncodeStatus *status;
    CamelStream *input_stream;
    gint nb_read_in_input = 0;
    guchar c;
    gint j = 0;
    gboolean end_of_read = FALSE;
    
    g_assert (stream);
    input_stream = stream_b64->input_stream;
    
    g_assert (input_stream);

    /* I don't know why the caller would want to 
       read a zero length buffer but ... */
    if (n == 0)
        return 0;


    status = &(stream_b64->status.encode_status);
    
    
    if (status->end_state == 0) { 
        /* we are not at the end of the input steam, 
           process the data normally */
        
        while ((j<n) && !end_of_read) {
            
            /* check if we must break the encoded line */
            if (status->line_length == 76) {
                buffer [j++] = '\n';
                status->line_length = 0;
                break;
            }
            
            /* 
             * because we encode four characters for 
             * 3 bytes, the last char does not need any  
             * read to write in the stream
             */
            if (status->state == 3) {
                buffer [j++] = status->keep;
                status->keep = 0;
                status->line_length++;
                break;
            }
            
            /* 
             * in all the other phases of the stream 
             * writing, we need to read a byte from the
             * input stream 
             */
            nb_read_in_input = camel_stream_read (input_stream, &c, 1);
            
            if (nb_read_in_input > 0) {
                switch (status->state){

                case 0:             
                    buffer [j++] = six_bits_to_char [c >> 2];
                    status->keep = (c & 0xc0 ) >> 2;
                    break;
                    
                case 1:
                    buffer [j++] = six_bits_to_char [status->keep | (c >> 4)];
                    status->keep = (c & 0x0f ) << 2;
                    break;
                    
                case 2:
                    buffer [j++] = six_bits_to_char [status->keep | (c >> 6)] ;
                    status->keep = (c & 0x3f );
                    break;
                    
                }
                
                status->state = (status->state + 1) % 4;
                status->line_length++;
            } else 
                end_of_read = TRUE;
            
            
            if (camel_stream_eos (input_stream))
                status->end_state = 1;
            
        }
    }
    
    /* 
     * now comes the real annoying part. Because some clients
     * expect the b64 encoded sequence length to be multiple of 4,
     * we must pad the end with '='. 
     * This is trivial when we write to stream as much as we want
     * but this is not the case when we are limited in the number
     * of chars we can write to the output stream. The consequence
     * of this is that we must keep the state of the writing
     * so that we can resume the next time this routine is called. 
     */

    if ( status->end_state != 0) { 
        
        /* 
         * we are at the end of the input stream
         * we must pad the output with '='.
         */

        while ((j<n) && (status->end_state != 6)) {
            
            if (status->end_state == 5) {

                status->end_state = 6;
                buffer [j++] = '\n';
                stream_b64->eos = TRUE;

            } else {
                
                switch (status->state) {
                    
                /* 
                 * depending on state of the decoder, we need to 
                 * write different things. 
                 */
                case 0:        
                /* 
                 * everyting has been written already and the
                 * output length is already a multiple of 3
                 * so that we have nothing to do.  
                 */
                    status->end_state = 5;
                    break;
                    
                case 1:
                /* 
                 * we have something in keep  
                 * and two '=' we must write
                 */
                    switch (status->end_state) {
                    case 1:
                        buffer [j++] = six_bits_to_char [status->keep] ;
                        status->end_state++;
                        break;
                    case 2:
                        buffer [j++] = '=';
                        status->end_state++;
                        break;
                    case 3:
                        buffer [j++] = '=';
                        status->end_state = 5;
                        break;
                    }
                    
                    
                    status->end_state++;
                    break;
                    
                    
                case 2:
                /* 
                 * we have something in keep  
                 * and one '=' we must write
                 */
                    switch (status->end_state) {
                    case 1:
                        buffer [j++] = six_bits_to_char [status->keep];
                        status->end_state++;
                        break;
                    case 2:
                        buffer [j++] = '=';
                        status->end_state = 5;
                        break;
                    }
                    
                    break;
                    
                case 3:
                /* 
                 * we have something in keep we must write
                 */
                    switch (status->end_state) {
                    case 1:
                        buffer [j++] = six_bits_to_char [status->keep];
                        status->end_state++;
                        break;
                    case 2:
                        buffer [j++] = '=';
                        status->end_state = 5;
                        break;
                    }
                    
                    break;
                }
                
                
            }
        }
        
    }

    return j;
}
    
    
    
    
    
static gboolean
my_eos (CamelStream *stream)
{
    CamelStreamB64 *stream_b64 = CAMEL_STREAM_B64 (stream);
    
    g_assert (stream);
    g_assert (stream_b64->input_stream);
    
    return (stream_b64->eos);
}





static void 
my_reset (CamelStream *stream)
{
    CamelStreamB64 *stream_b64 = CAMEL_STREAM_B64 (stream);
    
    g_assert (stream);
    g_assert (stream_b64->input_stream);
    
    stream_b64->status.decode_status.keep = 0;
    stream_b64->status.decode_status.state = 0;
    
    camel_stream_reset (stream_b64->input_stream);
}