/* 
   * Cryptographic API.
   *
   * MD5 Message Digest Algorithm (RFC1321).
   *
   * Derived from cryptoapi implementation, originally based on the
   * public domain implementation written by Colin Plumb in 1993.
   *
   * Copyright (c) Cryptoapi developers.
   * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
   * 
   * 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.
   *
   */

  #include <crypto/internal/hash.h>

  #include <crypto/md5.h>

  #include <linux/init.h>
  #include <linux/module.h>
  #include <linux/string.h>

  #include <linux/types.h>

  #include <linux/cryptohash.h>

  #include <asm/byteorder.h>

  /* XXX: this stuff can be optimized */
  static inline void le32_to_cpu_array(u32 *buf, unsigned int words)
  {
  	while (words--) {
  		__le32_to_cpus(buf);
  		buf++;
  	}
  }
  
  static inline void cpu_to_le32_array(u32 *buf, unsigned int words)
  {
  	while (words--) {
  		__cpu_to_le32s(buf);
  		buf++;
  	}
  }

  static inline void md5_transform_helper(struct md5_state *ctx)

  {
  	le32_to_cpu_array(ctx->block, sizeof(ctx->block) / sizeof(u32));
  	md5_transform(ctx->hash, ctx->block);
  }

  static int md5_init(struct shash_desc *desc)

  {

  	struct md5_state *mctx = shash_desc_ctx(desc);

  
  	mctx->hash[0] = 0x67452301;
  	mctx->hash[1] = 0xefcdab89;
  	mctx->hash[2] = 0x98badcfe;
  	mctx->hash[3] = 0x10325476;
  	mctx->byte_count = 0;

  
  	return 0;

  }

  static int md5_update(struct shash_desc *desc, const u8 *data, unsigned int len)

  {

  	struct md5_state *mctx = shash_desc_ctx(desc);

  	const u32 avail = sizeof(mctx->block) - (mctx->byte_count & 0x3f);
  
  	mctx->byte_count += len;
  
  	if (avail > len) {
  		memcpy((char *)mctx->block + (sizeof(mctx->block) - avail),
  		       data, len);

  		return 0;

  	}
  
  	memcpy((char *)mctx->block + (sizeof(mctx->block) - avail),
  	       data, avail);
  
  	md5_transform_helper(mctx);
  	data += avail;
  	len -= avail;
  
  	while (len >= sizeof(mctx->block)) {
  		memcpy(mctx->block, data, sizeof(mctx->block));
  		md5_transform_helper(mctx);
  		data += sizeof(mctx->block);
  		len -= sizeof(mctx->block);
  	}
  
  	memcpy(mctx->block, data, len);

  
  	return 0;

  }

  static int md5_final(struct shash_desc *desc, u8 *out)

  {

  	struct md5_state *mctx = shash_desc_ctx(desc);

  	const unsigned int offset = mctx->byte_count & 0x3f;
  	char *p = (char *)mctx->block + offset;
  	int padding = 56 - (offset + 1);
  
  	*p++ = 0x80;
  	if (padding < 0) {
  		memset(p, 0x00, padding + sizeof (u64));
  		md5_transform_helper(mctx);
  		p = (char *)mctx->block;
  		padding = 56;
  	}
  
  	memset(p, 0, padding);
  	mctx->block[14] = mctx->byte_count << 3;
  	mctx->block[15] = mctx->byte_count >> 29;
  	le32_to_cpu_array(mctx->block, (sizeof(mctx->block) -
  	                  sizeof(u64)) / sizeof(u32));
  	md5_transform(mctx->hash, mctx->block);
  	cpu_to_le32_array(mctx->hash, sizeof(mctx->hash) / sizeof(u32));
  	memcpy(out, mctx->hash, sizeof(mctx->hash));
  	memset(mctx, 0, sizeof(*mctx));

  
  	return 0;

  }

  static int md5_export(struct shash_desc *desc, void *out)
  {
  	struct md5_state *ctx = shash_desc_ctx(desc);
  
  	memcpy(out, ctx, sizeof(*ctx));
  	return 0;
  }
  
  static int md5_import(struct shash_desc *desc, const void *in)
  {
  	struct md5_state *ctx = shash_desc_ctx(desc);
  
  	memcpy(ctx, in, sizeof(*ctx));
  	return 0;
  }

  static struct shash_alg alg = {
  	.digestsize	=	MD5_DIGEST_SIZE,
  	.init		=	md5_init,
  	.update		=	md5_update,
  	.final		=	md5_final,

  	.export		=	md5_export,
  	.import		=	md5_import,
  	.descsize	=	sizeof(struct md5_state),

  	.statesize	=	sizeof(struct md5_state),

  	.base		=	{
  		.cra_name	=	"md5",
  		.cra_flags	=	CRYPTO_ALG_TYPE_SHASH,
  		.cra_blocksize	=	MD5_HMAC_BLOCK_SIZE,
  		.cra_module	=	THIS_MODULE,
  	}

  };

  static int __init md5_mod_init(void)

  {

  	return crypto_register_shash(&alg);

  }

  static void __exit md5_mod_fini(void)

  {

  	crypto_unregister_shash(&alg);

  }

  module_init(md5_mod_init);
  module_exit(md5_mod_fini);

  
  MODULE_LICENSE("GPL");
  MODULE_DESCRIPTION("MD5 Message Digest Algorithm");