libisofs/libisofs/md5.c

/*
 * Copyright (c) 2009 Thomas Schmitt
 *
 * This file is part of the libisofs project; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation. See COPYING file for details.
 */


#include <stdint.h>
#include <stdlib.h>
#include <string.h>

#include "writer.h"
#include "messages.h"
#include "ecma119.h"
#include "image.h"

#include "md5.h"


/* This code is derived from RFC 1321 and implements computation of the
    "RSA Data Security, Inc. MD5 Message-Digest Algorithm" */

#define Libisofs_md5_S11 7
#define Libisofs_md5_S12 12
#define Libisofs_md5_S13 17
#define Libisofs_md5_S14 22
#define Libisofs_md5_S21 5
#define Libisofs_md5_S22 9
#define Libisofs_md5_S23 14
#define Libisofs_md5_S24 20
#define Libisofs_md5_S31 4
#define Libisofs_md5_S32 11
#define Libisofs_md5_S33 16
#define Libisofs_md5_S34 23
#define Libisofs_md5_S41 6
#define Libisofs_md5_S42 10
#define Libisofs_md5_S43 15
#define Libisofs_md5_S44 21


/* F, G, H and I are basic MD5 functions.
 */
#define Libisofs_md5_F(x, y, z) (((x) & (y)) | ((~x) & (z)))
#define Libisofs_md5_G(x, y, z) (((x) & (z)) | ((y) & (~z)))
#define Libisofs_md5_H(x, y, z) ((x) ^ (y) ^ (z))
#define Libisofs_md5_I(x, y, z) ((y) ^ ((x) | (~z)))

/* ROTATE_LEFT rotates x left n bits.
 */
#define Libisofs_md5_ROTATE_LEFT(x, n) (((x) << (n)) | ((x) >> (32-(n))))

/* FF, GG, HH, and II transformations for rounds 1, 2, 3, and 4.
Rotation is separate from addition to prevent recomputation.
 */
#define Libisofs_md5_FF(a, b, c, d, x, s, ac) { \
 (a) += Libisofs_md5_F ((b), (c), (d)) + (x) + (uint32_t)(ac); \
 (a) = Libisofs_md5_ROTATE_LEFT ((a), (s)); \
 (a) += (b); \
  }
#define Libisofs_md5_GG(a, b, c, d, x, s, ac) { \
 (a) += Libisofs_md5_G ((b), (c), (d)) + (x) + (uint32_t)(ac); \
 (a) = Libisofs_md5_ROTATE_LEFT ((a), (s)); \
 (a) += (b); \
  }
#define Libisofs_md5_HH(a, b, c, d, x, s, ac) { \
 (a) += Libisofs_md5_H ((b), (c), (d)) + (x) + (uint32_t)(ac); \
 (a) = Libisofs_md5_ROTATE_LEFT ((a), (s)); \
 (a) += (b); \
  }
#define Libisofs_md5_II(a, b, c, d, x, s, ac) { \
 (a) += Libisofs_md5_I ((b), (c), (d)) + (x) + (uint32_t)(ac); \
 (a) = Libisofs_md5_ROTATE_LEFT ((a), (s)); \
 (a) += (b); \
  }


/* MD5 context. */
struct _libisofs_md5_ctx {
  uint32_t state[4];                                   /* state (ABCD) */
  uint32_t count[2];        /* number of bits, modulo 2^64 (lsb first) */
  unsigned char buffer[64];                         /* input buffer */
};

typedef struct _libisofs_md5_ctx libisofs_md5_ctx;


/* MD5 basic transformation. Transforms state based on block.
 */
static int md5__transform (uint32_t state[4], unsigned char block[64])
{
 uint32_t a = state[0], b = state[1], c = state[2], d = state[3], x[16];
 unsigned int i, j;

 for (i = 0, j = 0; j < 64; i++, j += 4)
   x[i] = ((uint32_t)block[j]) | (((uint32_t)block[j+1]) << 8) |
    (((uint32_t)block[j+2]) << 16) | (((uint32_t)block[j+3]) << 24);

  /* Round 1 */
  Libisofs_md5_FF (a, b, c, d, x[ 0], Libisofs_md5_S11, 0xd76aa478); /* 1 */
  Libisofs_md5_FF (d, a, b, c, x[ 1], Libisofs_md5_S12, 0xe8c7b756); /* 2 */
  Libisofs_md5_FF (c, d, a, b, x[ 2], Libisofs_md5_S13, 0x242070db); /* 3 */
  Libisofs_md5_FF (b, c, d, a, x[ 3], Libisofs_md5_S14, 0xc1bdceee); /* 4 */
  Libisofs_md5_FF (a, b, c, d, x[ 4], Libisofs_md5_S11, 0xf57c0faf); /* 5 */
  Libisofs_md5_FF (d, a, b, c, x[ 5], Libisofs_md5_S12, 0x4787c62a); /* 6 */
  Libisofs_md5_FF (c, d, a, b, x[ 6], Libisofs_md5_S13, 0xa8304613); /* 7 */
  Libisofs_md5_FF (b, c, d, a, x[ 7], Libisofs_md5_S14, 0xfd469501); /* 8 */
  Libisofs_md5_FF (a, b, c, d, x[ 8], Libisofs_md5_S11, 0x698098d8); /* 9 */
  Libisofs_md5_FF (d, a, b, c, x[ 9], Libisofs_md5_S12, 0x8b44f7af); /* 10 */
  Libisofs_md5_FF (c, d, a, b, x[10], Libisofs_md5_S13, 0xffff5bb1); /* 11 */
  Libisofs_md5_FF (b, c, d, a, x[11], Libisofs_md5_S14, 0x895cd7be); /* 12 */
  Libisofs_md5_FF (a, b, c, d, x[12], Libisofs_md5_S11, 0x6b901122); /* 13 */
  Libisofs_md5_FF (d, a, b, c, x[13], Libisofs_md5_S12, 0xfd987193); /* 14 */
  Libisofs_md5_FF (c, d, a, b, x[14], Libisofs_md5_S13, 0xa679438e); /* 15 */
  Libisofs_md5_FF (b, c, d, a, x[15], Libisofs_md5_S14, 0x49b40821); /* 16 */

  /* Round 2 */
  Libisofs_md5_GG (a, b, c, d, x[ 1], Libisofs_md5_S21, 0xf61e2562); /* 17 */
  Libisofs_md5_GG (d, a, b, c, x[ 6], Libisofs_md5_S22, 0xc040b340); /* 18 */
  Libisofs_md5_GG (c, d, a, b, x[11], Libisofs_md5_S23, 0x265e5a51); /* 19 */
  Libisofs_md5_GG (b, c, d, a, x[ 0], Libisofs_md5_S24, 0xe9b6c7aa); /* 20 */
  Libisofs_md5_GG (a, b, c, d, x[ 5], Libisofs_md5_S21, 0xd62f105d); /* 21 */
  Libisofs_md5_GG (d, a, b, c, x[10], Libisofs_md5_S22,  0x2441453); /* 22 */
  Libisofs_md5_GG (c, d, a, b, x[15], Libisofs_md5_S23, 0xd8a1e681); /* 23 */
  Libisofs_md5_GG (b, c, d, a, x[ 4], Libisofs_md5_S24, 0xe7d3fbc8); /* 24 */
  Libisofs_md5_GG (a, b, c, d, x[ 9], Libisofs_md5_S21, 0x21e1cde6); /* 25 */
  Libisofs_md5_GG (d, a, b, c, x[14], Libisofs_md5_S22, 0xc33707d6); /* 26 */
  Libisofs_md5_GG (c, d, a, b, x[ 3], Libisofs_md5_S23, 0xf4d50d87); /* 27 */
  Libisofs_md5_GG (b, c, d, a, x[ 8], Libisofs_md5_S24, 0x455a14ed); /* 28 */
  Libisofs_md5_GG (a, b, c, d, x[13], Libisofs_md5_S21, 0xa9e3e905); /* 29 */
  Libisofs_md5_GG (d, a, b, c, x[ 2], Libisofs_md5_S22, 0xfcefa3f8); /* 30 */
  Libisofs_md5_GG (c, d, a, b, x[ 7], Libisofs_md5_S23, 0x676f02d9); /* 31 */
  Libisofs_md5_GG (b, c, d, a, x[12], Libisofs_md5_S24, 0x8d2a4c8a); /* 32 */

  /* Round 3 */
  Libisofs_md5_HH (a, b, c, d, x[ 5], Libisofs_md5_S31, 0xfffa3942); /* 33 */
  Libisofs_md5_HH (d, a, b, c, x[ 8], Libisofs_md5_S32, 0x8771f681); /* 34 */
  Libisofs_md5_HH (c, d, a, b, x[11], Libisofs_md5_S33, 0x6d9d6122); /* 35 */
  Libisofs_md5_HH (b, c, d, a, x[14], Libisofs_md5_S34, 0xfde5380c); /* 36 */
  Libisofs_md5_HH (a, b, c, d, x[ 1], Libisofs_md5_S31, 0xa4beea44); /* 37 */
  Libisofs_md5_HH (d, a, b, c, x[ 4], Libisofs_md5_S32, 0x4bdecfa9); /* 38 */
  Libisofs_md5_HH (c, d, a, b, x[ 7], Libisofs_md5_S33, 0xf6bb4b60); /* 39 */
  Libisofs_md5_HH (b, c, d, a, x[10], Libisofs_md5_S34, 0xbebfbc70); /* 40 */
  Libisofs_md5_HH (a, b, c, d, x[13], Libisofs_md5_S31, 0x289b7ec6); /* 41 */
  Libisofs_md5_HH (d, a, b, c, x[ 0], Libisofs_md5_S32, 0xeaa127fa); /* 42 */
  Libisofs_md5_HH (c, d, a, b, x[ 3], Libisofs_md5_S33, 0xd4ef3085); /* 43 */
  Libisofs_md5_HH (b, c, d, a, x[ 6], Libisofs_md5_S34,  0x4881d05); /* 44 */
  Libisofs_md5_HH (a, b, c, d, x[ 9], Libisofs_md5_S31, 0xd9d4d039); /* 45 */
  Libisofs_md5_HH (d, a, b, c, x[12], Libisofs_md5_S32, 0xe6db99e5); /* 46 */
  Libisofs_md5_HH (c, d, a, b, x[15], Libisofs_md5_S33, 0x1fa27cf8); /* 47 */
  Libisofs_md5_HH (b, c, d, a, x[ 2], Libisofs_md5_S34, 0xc4ac5665); /* 48 */

  /* Round 4 */
  Libisofs_md5_II (a, b, c, d, x[ 0], Libisofs_md5_S41, 0xf4292244); /* 49 */
  Libisofs_md5_II (d, a, b, c, x[ 7], Libisofs_md5_S42, 0x432aff97); /* 50 */
  Libisofs_md5_II (c, d, a, b, x[14], Libisofs_md5_S43, 0xab9423a7); /* 51 */
  Libisofs_md5_II (b, c, d, a, x[ 5], Libisofs_md5_S44, 0xfc93a039); /* 52 */
  Libisofs_md5_II (a, b, c, d, x[12], Libisofs_md5_S41, 0x655b59c3); /* 53 */
  Libisofs_md5_II (d, a, b, c, x[ 3], Libisofs_md5_S42, 0x8f0ccc92); /* 54 */
  Libisofs_md5_II (c, d, a, b, x[10], Libisofs_md5_S43, 0xffeff47d); /* 55 */
  Libisofs_md5_II (b, c, d, a, x[ 1], Libisofs_md5_S44, 0x85845dd1); /* 56 */
  Libisofs_md5_II (a, b, c, d, x[ 8], Libisofs_md5_S41, 0x6fa87e4f); /* 57 */
  Libisofs_md5_II (d, a, b, c, x[15], Libisofs_md5_S42, 0xfe2ce6e0); /* 58 */
  Libisofs_md5_II (c, d, a, b, x[ 6], Libisofs_md5_S43, 0xa3014314); /* 59 */
  Libisofs_md5_II (b, c, d, a, x[13], Libisofs_md5_S44, 0x4e0811a1); /* 60 */
  Libisofs_md5_II (a, b, c, d, x[ 4], Libisofs_md5_S41, 0xf7537e82); /* 61 */
  Libisofs_md5_II (d, a, b, c, x[11], Libisofs_md5_S42, 0xbd3af235); /* 62 */
  Libisofs_md5_II (c, d, a, b, x[ 2], Libisofs_md5_S43, 0x2ad7d2bb); /* 63 */
  Libisofs_md5_II (b, c, d, a, x[ 9], Libisofs_md5_S44, 0xeb86d391); /* 64 */

  state[0] += a;
  state[1] += b;
  state[2] += c;
  state[3] += d;

  /* Zeroize sensitive information. */
  memset ((char *) x, 0, sizeof (x));
  return(1);
}


static int md5__encode(unsigned char *output, uint32_t *input,
                       unsigned int len)
{
  unsigned int i, j;

  for (i = 0, j = 0; j < len; i++, j += 4) {
    output[j] = (unsigned char)(input[i] & 0xff);
    output[j+1] = (unsigned char)((input[i] >> 8) & 0xff);
    output[j+2] = (unsigned char)((input[i] >> 16) & 0xff);
    output[j+3] = (unsigned char)((input[i] >> 24) & 0xff);
  }
  return(1);
}



static int md5_init(libisofs_md5_ctx *ctx, int flag)
{
 ctx->count[0] = ctx->count[1] = 0;
 /* Load magic initialization constants. */
 ctx->state[0] = 0x67452301;
 ctx->state[1] = 0xefcdab89;
 ctx->state[2] = 0x98badcfe;
 ctx->state[3] = 0x10325476;
 return(1);
}


/* MD5 block update operation. Continues an MD5 message-digest
  operation, processing another message block, and updating the
  context.
 */
static int md5_update(libisofs_md5_ctx *ctx, unsigned char *data,
                      int datalen, int flag)
{
 unsigned int i, index, partlen;

 /* Compute number of bytes mod 64 */
 index = (unsigned int)((ctx->count[0] >> 3) & 0x3F);
 /* Update number of bits */
 if ((ctx->count[0] += ((uint32_t) datalen << 3)) < 
     ((uint32_t) datalen << 3))
   ctx->count[1]++;
 ctx->count[1] += ((uint32_t) datalen >> 29);
 partlen = 64 - index;

 /* Transform as many times as possible. */
 if (datalen >= partlen) {
   memcpy((char *) &ctx->buffer[index], (char *) data, partlen);
   md5__transform(ctx->state, ctx->buffer);
   for (i = partlen; i + 63 < datalen; i += 64)
     md5__transform(ctx->state, &data[i]);
   index = 0;
 } else
   i = 0;

 /* Buffer remaining data */
 memcpy((char *) &ctx->buffer[index], (char *) &data[i],datalen-i);

 return(1);
}


static int md5_final(libisofs_md5_ctx *ctx, char result[16], int flag)
{
 unsigned char bits[8], *respt;
 unsigned int index, padlen;
 static unsigned char PADDING[64] = {
   0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
   0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
   0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
 };

 /* Save number of bits */
 md5__encode(bits, ctx->count, 8);
 /* Pad out to 56 mod 64.  */
 index = (unsigned int)((ctx->count[0] >> 3) & 0x3f);
 padlen = (index < 56) ? (56 - index) : (120 - index);
 md5_update(ctx, PADDING, padlen,0);
 /* Append length (before padding) */
 md5_update(ctx, bits, 8,0);
 /* Store state in result */
 respt= (unsigned char *) result;
 md5__encode(respt, ctx->state, 16);
 /* Zeroize sensitive information.  */
 memset ((char *) ctx, 0, sizeof (*ctx));
 return(1);
}


int libisofs_md5(void **ctx_in, char *data, int datalen,
                 char result[16], int flag)
/* *ctx has to be NULL or point to freeable memory */
/*
 bit0= allocate and init *ctx
 bit1= transfer ctx to result
 bit2= with bit 0 : clone new *ctx from data
 bit15= free *ctx
*/
{
 unsigned char *datapt;
 libisofs_md5_ctx **ctx;

 ctx= (libisofs_md5_ctx **) ctx_in;
 if(flag&1) {
   if(*ctx!=NULL)
     free((char *) *ctx);
   *ctx= calloc(1, sizeof(libisofs_md5_ctx));
   if(*ctx==NULL)
     return(-1);
   md5_init(*ctx,0);
   if(flag&4)
     memcpy((char *) *ctx,data,sizeof(libisofs_md5_ctx));
 }
 if(*ctx==NULL)
   return(0);
 if(datalen>0) {
   datapt= (unsigned char *) data;
   md5_update(*ctx, datapt, datalen, 0);
 }
 if(flag&2)
   md5_final(*ctx, result, 0);
 if(flag&(1<<15)) {
   free((char *) *ctx);
   *ctx= NULL;
 }
 return(1);
}


/* ----------------------------------------------------------------------- */


/* Function to identify and manage md5sum indice of the old image.
 * data is supposed to be a 4 byte integer, bit 31 shall be 0,
 * value 0 of this integer means that it is not a valid index.
 */
int checksum_xinfo_func(void *data, int flag)
{
    /* data is an int disguised as pointer. It does not point to memory. */
    return 1;
}


#ifdef Libisofs_with_checksumS

/*
  @flag bit0= recursion
        bit1= session will be appended to an existing image
*/
static
int checksum_copy_old_nodes(Ecma119Image *target, IsoNode *node, int flag)
{
    IsoNode *pos;
    IsoFile *file;
    IsoImage *img;
    int ret, i;
    size_t value_length;
    unsigned int idx = 0, old_idx = 0;
    char *value = NULL;
    void *xipt;

    img = target->image;
    if (img->checksum_array == NULL || target->checksum_buffer == NULL)
        return 0;

    if (node->type == LIBISO_FILE) {
        file = (IsoFile *) node;
        if (file->from_old_session) {
            ret = iso_node_get_xinfo(node, checksum_xinfo_func, &xipt);
            if (ret <= 0)
                return ret;
            /* xipt is an int disguised as void pointer */
            old_idx = 0;
            for (i = 0; i < 4; i++)
                old_idx = (old_idx << 8) | ((unsigned char *) &xipt)[i];

            if (old_idx == 0 || old_idx > img->checksum_idx_count - 1)
                return 0;

            ret = iso_node_lookup_attr(node, "isofs.cx", &value_length,
                                       &value, 0);
            if (ret == 1 && value_length == 4) {
                for (i = 0; i < 4; i++)
                    idx = (idx << 8) | ((unsigned char *) value)[i];
                if (idx > 0 && idx <= target->checksum_idx_counter) {
                    memcpy(target->checksum_buffer + 16 * idx,
                           img->checksum_array + 16 * old_idx, 16);
                }
            }
            if (value != NULL)
                free(value);
        }
    } else if (node->type == LIBISO_DIR) {
        for (pos = ((IsoDir *) node)->children; pos != NULL; pos = pos->next) {
            ret = checksum_copy_old_nodes(target, pos, 1);
            if (ret < 0)
                return ret;
        }
    }
    return ISO_SUCCESS;
}

#endif /* Libisofs_with_checksumS */


static
int checksum_writer_compute_data_blocks(IsoImageWriter *writer)
{

#ifdef Libisofs_with_checksumS

    size_t size;
    Ecma119Image *t;
    int ret;
    unsigned int lba;

    if (writer == NULL) {
        return ISO_ASSERT_FAILURE;
    }
    t = writer->target;

    lba = t->curblock; /* (t->curblock already contains t->ms_block) */ 
    size = (t->checksum_idx_counter + 2) / 128 + 1;
    t->curblock += size;

    /* >>> ??? reserve extra block for stream detectable checksum */;

    /* Allocate array of MD5 sums */
    t->checksum_buffer = calloc(size, 2048);
    if (t->checksum_buffer == NULL)
        return ISO_OUT_OF_MEM;

    /* Copy MD5 from nodes of old image into writer->data */
    ret = checksum_copy_old_nodes(t, (IsoNode *) t->image->root, 0);
    if (ret < 0)
        return ret;

    /* Record lba,count,size,cecksum_type in "isofs.ca" of root node */
    ret = iso_root_set_isofsca((IsoNode *) t->image->root,
                               (unsigned int) t->ms_block, lba,
                               t->checksum_idx_counter + 2, 16, "MD5", 0);
    if (ret < 0)
        return ret;

#endif /* Libisofs_with_checksumS */

    return ISO_SUCCESS;
}


static
int checksum_writer_write_vol_desc(IsoImageWriter *writer)
{
    /* nothing needed */
    return ISO_SUCCESS;
}


static
int checksum_writer_write_data(IsoImageWriter *writer)
{

#ifdef Libisofs_with_checksumS

    int wres, res;
    size_t i, size;
    Ecma119Image *t;

    if (writer == NULL) {
        return ISO_ASSERT_FAILURE;
    }

    t = writer->target;
    iso_msg_debug(t->image->id, "Writing Checksums...");

    /* Write image checksum to index 0 */
    /* >>> rather fork a result than killing t->checksum_ctx */;
    res = libisofs_md5(&(t->checksum_ctx), NULL, 0, t->image_md5,
                       2 | (1 << 15));
    if (res > 0)
        memcpy(t->checksum_buffer + 0, t->image_md5, 16);

    size = (t->checksum_idx_counter + 2) / 128 + 1;
 
    /* >>> write overall checksum as index t->checksum_idx_counter + 1 */;

    for (i = 0; i < size; i++) {
        wres = iso_write(t, t->checksum_buffer + ((size_t) 2048) * i,
                         BLOCK_SIZE);
        if (wres < 0)
            return wres;
    }

    /* >>> write scdbackup checksum tag to an extra block */;

#endif /* Libisofs_with_checksumS */

    return ISO_SUCCESS;
}


static
int checksum_writer_free_data(IsoImageWriter *writer)
{
    /* nothing was allocated at writer->data */
    return ISO_SUCCESS;
}


int checksum_writer_create(Ecma119Image *target)
{
    IsoImageWriter *writer;
    
    writer = malloc(sizeof(IsoImageWriter));
    if (writer == NULL) {
        return ISO_OUT_OF_MEM;
    }
    
    writer->compute_data_blocks = checksum_writer_compute_data_blocks;
    writer->write_vol_desc = checksum_writer_write_vol_desc;
    writer->write_data = checksum_writer_write_data;
    writer->free_data = checksum_writer_free_data;
    writer->data = NULL;
    writer->target = target;

    /* add this writer to image */
    target->writers[target->nwriters++] = writer;

    return ISO_SUCCESS;
}