Synnefo » Pithos MS Client

#region

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

 * <copyright file="Signature.cs" company="GRNet">

 * 

 * Copyright 2011-2012 GRNET S.A. All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or

 * without modification, are permitted provided that the following

 * conditions are met:

 *

 *   1. Redistributions of source code must retain the above

 *      copyright notice, this list of conditions and the following

 *      disclaimer.

 *

 *   2. Redistributions in binary form must reproduce the above

 *      copyright notice, this list of conditions and the following

 *      disclaimer in the documentation and/or other materials

 *      provided with the distribution.

 *

 *

 * THIS SOFTWARE IS PROVIDED BY GRNET S.A. ``AS IS'' AND ANY EXPRESS

 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED

 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL GRNET S.A OR

 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT

 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF

 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED

 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT

 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN

 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE

 * POSSIBILITY OF SUCH DAMAGE.

 *

 * The views and conclusions contained in the software and

 * documentation are those of the authors and should not be

 * interpreted as representing official policies, either expressed

 * or implied, of GRNET S.A.

 * </copyright>

 * -----------------------------------------------------------------------

 */

#endregion

using System;

using System.Collections.Concurrent;

using System.Collections.Generic;

using System.Diagnostics.Contracts;

using System.IO;

using System.Reflection;

using System.Runtime.Remoting.Metadata.W3cXsd2001;

using System.Security.Cryptography;

using System.Threading.Tasks;

using System.Linq;

namespace Pithos.Network

{

    public static class Signature

    {

        private static readonly log4net.ILog Log = log4net.LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);

        public static string CalculateMD5(FileInfo info)

        {

            if (info==null)

                throw new ArgumentNullException("info");

            if (String.IsNullOrWhiteSpace(info.FullName))

                throw new ArgumentException("info.FullName is empty","info");

            Contract.EndContractBlock();

            return CalculateMD5(info.FullName);

        }

        public static string CalculateMD5(string path)

        {

            if (String.IsNullOrWhiteSpace(path))

                throw new ArgumentNullException("path");

            Contract.EndContractBlock();

            //DON'T calculate hashes for folders

            if (Directory.Exists(path))

                return "";

            string hash;

            using (var hasher = MD5.Create())

            using (var stream = new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.Read, 65536, true))

            {

                var hashBytes = hasher.ComputeHash(stream);

                hash = hashBytes.ToHashString();

            }

            return hash;

        }

/*

        public static string BytesToString(byte[] hashBytes)

        {

            var shb=new SoapHexBinary(hashBytes);

            return shb.ToString();

        }

        public static byte[] StringToBytes(string hash)

        {

            var shb=SoapHexBinary.Parse(hash);

            return shb.Value;

        }

*/

        public static byte[] ToBytes(this string hash)

        {

            var shb = SoapHexBinary.Parse(hash);

            return shb.Value;

        }

        public static string ToHashString(this byte[] hashBytes)

        {

            var shb = new SoapHexBinary(hashBytes);

            return shb.ToString().ToLower();

        }

        public static TreeHash CalculateTreeHash(FileSystemInfo fileInfo, int blockSize, string algorithm)

        {

            if (fileInfo == null)

                throw new ArgumentNullException("fileInfo");

            if (String.IsNullOrWhiteSpace(fileInfo.FullName))

                throw new ArgumentException("fileInfo.FullName is empty", "fileInfo");

            if (blockSize <= 0)

                throw new ArgumentOutOfRangeException("blockSize", "blockSize must be a value greater than zero ");

            if (String.IsNullOrWhiteSpace(algorithm))

                throw new ArgumentNullException("algorithm");

            Contract.EndContractBlock();

            fileInfo.Refresh();

            if (fileInfo is DirectoryInfo || !fileInfo.Exists)

                return TreeHash.Empty;

            return CalculateTreeHash(fileInfo.FullName, blockSize, algorithm);

        }

        /// <summary>

        /// Calculates a file's tree hash synchronously, using the specified block size

        /// </summary>

        /// <param name="filePath">Path to an existing file</param>

        /// <param name="blockSize">Block size used to calculate leaf hashes</param>

        /// <param name="algorithm"></param>

        /// <returns>A <see cref="TreeHash"/> with the block hashes and top hash</returns>

        public static TreeHash CalculateTreeHash(string filePath, int blockSize, string algorithm)

        {

            if (String.IsNullOrWhiteSpace(filePath))

                throw new ArgumentNullException("filePath");

            if (blockSize<=0)

                throw new ArgumentOutOfRangeException("blockSize","blockSize must be a value greater than zero ");

            if (String.IsNullOrWhiteSpace(algorithm))

                throw new ArgumentNullException("algorithm");

            Contract.EndContractBlock();

            var hash=CalculateTreeHashAsync(filePath, blockSize, algorithm, 2);

            return hash.Result;

        }

        public static async Task<TreeHash> CalculateTreeHashAsync(FileInfo fileInfo, int blockSize, string algorithm, byte parallelism)

        {

            if (fileInfo == null)

                throw new ArgumentNullException("fileInfo");

            if (String.IsNullOrWhiteSpace(fileInfo.FullName))

                throw new ArgumentNullException("fileInfo.FullName is empty","fileInfo");

            if (blockSize <= 0)

                throw new ArgumentOutOfRangeException("blockSize", "blockSize must be a value greater than zero ");

            if (String.IsNullOrWhiteSpace(algorithm))

                throw new ArgumentNullException("algorithm");

            Contract.EndContractBlock();

            return await CalculateTreeHashAsync(fileInfo.FullName, blockSize, algorithm, parallelism);

        }

        public static async Task<TreeHash> CalculateTreeHashAsync(string filePath, int blockSize,string algorithm, int parallelism)

        {

            if (String.IsNullOrWhiteSpace(filePath))

                throw new ArgumentNullException("filePath");

            if (blockSize <= 0)

                throw new ArgumentOutOfRangeException("blockSize", "blockSize must be a value greater than zero ");

            if (String.IsNullOrWhiteSpace(algorithm))

                throw new ArgumentNullException("algorithm");

            Contract.EndContractBlock();

            if (Log.IsDebugEnabled)

                Log.DebugFormat("Calc Signature [{0}]",filePath);

            //DON'T calculate hashes for folders

            if (Directory.Exists(filePath))

                return new TreeHash(algorithm);

            //The hash of a non-existent file is the empty hash

            if (!File.Exists(filePath))

                return new TreeHash(algorithm);

            //Calculate the hash of all blocks using a blockhash iterator

            using (var stream = new FileStream(filePath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite, blockSize, true))

            {

                //Calculate the blocks asyncrhonously

                var hashes = await BlockHashAlgorithms.CalculateBlockHashesInPlacePFor(stream, blockSize, algorithm, parallelism);                

                //And then proceed with creating and returning a TreeHash

                var length = stream.Length;

                var list = hashes.OrderBy(pair => pair.Key).Select(pair => pair.Value).ToList();

                var treeHash = new TreeHash(algorithm)

                {

                    Bytes = length,

                    BlockSize = blockSize,

                    Hashes = list,

                };

                string fileHash;

                var hasher = HashAlgorithm.Create("MD5");

                stream.Position = 0;

                treeHash.MD5= hasher.ComputeHash(stream).ToHashString();

                return treeHash;

            }

        }

        public static byte[] CalculateTopHash(IList<byte[]> hashMap, string algorithm)

        {

            if (hashMap == null)

                throw new ArgumentNullException("hashMap");

            if (String.IsNullOrWhiteSpace(algorithm))

                throw new ArgumentNullException("algorithm");

            Contract.EndContractBlock();            

            var hashCount = hashMap.Count;

            //The tophash of an empty hashmap is an empty array

            if (hashCount == 0)

                return new byte[0];

            //The tophash of a one-item hashmap is the hash itself

            if (hashCount == 1)

                return hashMap[0];

            //Calculate the required number of leaf nodes

            var leafs =(int)Math.Pow(2, Math.Ceiling(Math.Log(hashCount,2)));

            //The size of all nodes is the same and equal to the size of the input hashes

            var hashSize = hashMap[0].Length;

            //If the hashmap containes fewer nodes than the required leaf count, we need to fill

            //the rest with empty blocks

            byte[] empty=null;            

            if (hashCount < leafs)

                empty = new byte[hashSize];

            //New hashes will be stored in a dictionary keyed by their step to preserve order

            var newHashes=new ConcurrentDictionary<int, byte[]>();            

            Parallel.For(0, leafs/2,

                (step, state) =>

                {

                    using (var hasher = HashAlgorithm.Create(algorithm))

                    {

                        var i = step*2;

                        var block1 = i <= hashCount - 1 ? hashMap[i] : empty;

                        var block2 = i <= hashCount - 2 ? hashMap[i + 1] : empty;

                        hasher.TransformBlock(block1, 0, block1.Length, null, 0);

                        hasher.TransformFinalBlock(block2, 0, block2.Length);

                        var finalHash = hasher.Hash;

                        //Store the final value in its proper place

                        newHashes[step] = finalHash;

                    }

                });

            //Extract the hashes to a list ordered by their step 

            var hashes = newHashes.OrderBy(pair => pair.Key).Select(pair => pair.Value).ToList();

            return CalculateTopHash(hashes, algorithm);                   

        }        

        public static byte[] CalculateHash(byte[] buffer,string algorithm)

        {

            if (buffer == null)

                throw new ArgumentNullException("buffer");

            if (String.IsNullOrWhiteSpace(algorithm))

                throw new ArgumentNullException("algorithm");

            Contract.EndContractBlock();

            using (var hasher = HashAlgorithm.Create(algorithm))

            {

                var hash = hasher.ComputeHash(buffer, 0, buffer.Length);

                return hash;

            }        

        }

    }

}