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🐛Move checksum initializers to instance constructors.

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This commit is contained in:
Natalia Portillo
2018-02-03 17:39:49 +00:00
parent 4b4671b4ef
commit b50b6c29ca
61 changed files with 1429 additions and 1599 deletions
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197
DiscImageChef.Checksums/SpamSumContext.cs
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@@ -49,12 +49,12 @@ namespace DiscImageChef.Checksums
/// </summary>
public class SpamSumContext : IChecksum
{
const uint ROLLING_WINDOW = 7;
const uint MIN_BLOCKSIZE = 3;
const uint HASH_PRIME = 0x01000193;
const uint HASH_INIT = 0x28021967;
const uint NUM_BLOCKHASHES = 31;
const uint SPAMSUM_LENGTH = 64;
const uint ROLLING_WINDOW = 7;
const uint MIN_BLOCKSIZE = 3;
const uint HASH_PRIME = 0x01000193;
const uint HASH_INIT = 0x28021967;
const uint NUM_BLOCKHASHES = 31;
const uint SPAMSUM_LENGTH = 64;
const uint FUZZY_MAX_RESULT = 2 * SPAMSUM_LENGTH + 20;
//"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
readonly byte[] b64 =
@@ -67,30 +67,70 @@ namespace DiscImageChef.Checksums
FuzzyState self;
void roll_init()
{
self.Roll = new RollState {Window = new byte[ROLLING_WINDOW]};
}
/// <summary>
/// Initializes the SpamSum structures
/// </summary>
public void Init()
public SpamSumContext()
{
self = new FuzzyState {Bh = new BlockhashContext[NUM_BLOCKHASHES]};
self =
new FuzzyState {Bh = new BlockhashContext[NUM_BLOCKHASHES]};
for(int i = 0; i < NUM_BLOCKHASHES; i++) self.Bh[i].Digest = new byte[SPAMSUM_LENGTH];
self.Bhstart = 0;
self.Bhend = 1;
self.Bh[0].H = HASH_INIT;
self.Bh[0].Halfh = HASH_INIT;
self.Bh[0].Digest[0] = 0;
self.Bhstart = 0;
self.Bhend = 1;
self.Bh[0].H = HASH_INIT;
self.Bh[0].Halfh = HASH_INIT;
self.Bh[0].Digest[0] = 0;
self.Bh[0].Halfdigest = 0;
self.Bh[0].Dlen = 0;
self.TotalSize = 0;
self.Bh[0].Dlen = 0;
self.TotalSize = 0;
roll_init();
}
/// <summary>
/// Updates the hash with data.
/// </summary>
/// <param name="data">Data buffer.</param>
/// <param name="len">Length of buffer to hash.</param>
public void Update(byte[] data, uint len)
{
self.TotalSize += len;
for(int i = 0; i < len; i++) fuzzy_engine_step(data[i]);
}
/// <summary>
/// Updates the hash with data.
/// </summary>
/// <param name="data">Data buffer.</param>
public void Update(byte[] data)
{
Update(data, (uint)data.Length);
}
/// <summary>
/// Returns a byte array of the hash value.
/// </summary>
public byte[] Final()
{
// SpamSum does not have a binary representation, or so it seems
throw new NotImplementedException("SpamSum does not have a binary representation.");
}
/// <summary>
/// Returns a base64 representation of the hash value.
/// </summary>
public string End()
{
FuzzyDigest(out byte[] result);
return CToString(result);
}
void roll_init()
{
self.Roll = new RollState {Window = new byte[ROLLING_WINDOW]};
}
/*
* a rolling hash, based on the Adler checksum. By using a rolling hash
* we can perform auto resynchronisation after inserts/deletes
@@ -116,7 +156,7 @@ namespace DiscImageChef.Checksums
* in theory should have no effect. This AND has been removed
* for performance (jk) */
self.Roll.H3 <<= 5;
self.Roll.H3 ^= c;
self.Roll.H3 ^= c;
}
uint roll_sum()
@@ -144,13 +184,13 @@ namespace DiscImageChef.Checksums
if(self.Bhend == 0) // assert
throw new Exception("Assertion failed");
obh = self.Bhend - 1;
nbh = self.Bhend;
self.Bh[nbh].H = self.Bh[obh].H;
self.Bh[nbh].Halfh = self.Bh[obh].Halfh;
self.Bh[nbh].Digest[0] = 0;
obh = self.Bhend - 1;
nbh = self.Bhend;
self.Bh[nbh].H = self.Bh[obh].H;
self.Bh[nbh].Halfh = self.Bh[obh].Halfh;
self.Bh[nbh].Digest[0] = 0;
self.Bh[nbh].Halfdigest = 0;
self.Bh[nbh].Dlen = 0;
self.Bh[nbh].Dlen = 0;
++self.Bhend;
}
@@ -165,6 +205,7 @@ namespace DiscImageChef.Checksums
* blocksize. */ return;
if(self.Bh[self.Bhstart + 1].Dlen < SPAMSUM_LENGTH / 2)
/* Estimate adjustment would select this blocksize. */ return;
/* At this point we are clearly no longer interested in the
* start_blocksize. Get rid of it. */
++self.Bhstart;
@@ -173,7 +214,7 @@ namespace DiscImageChef.Checksums
void fuzzy_engine_step(byte c)
{
ulong h;
uint i;
uint i;
/* At each character we update the rolling hash and the normal hashes.
* When the rolling hash hits a reset value then we emit a normal hash
* as a element of the signature and reset the normal hash. */
@@ -182,7 +223,7 @@ namespace DiscImageChef.Checksums
for(i = self.Bhstart; i < self.Bhend; ++i)
{
self.Bh[i].H = sum_hash(c, self.Bh[i].H);
self.Bh[i].H = sum_hash(c, self.Bh[i].H);
self.Bh[i].Halfh = sum_hash(c, self.Bh[i].Halfh);
}
@@ -193,12 +234,13 @@ namespace DiscImageChef.Checksums
/* Once this condition is false for one bs, it is
* automatically false for all further bs. I.e. if
* h === -1 (mod 2*bs) then h === -1 (mod bs). */ break;
/* We have hit a reset point. We now emit hashes which are
* based on all characters in the piece of the message between
* the last reset point and this one */
if(0 == self.Bh[i].Dlen) fuzzy_try_fork_blockhash();
self.Bh[i].Digest[self.Bh[i].Dlen] = b64[self.Bh[i].H % 64];
self.Bh[i].Halfdigest = b64[self.Bh[i].Halfh % 64];
self.Bh[i].Digest[self.Bh[i].Dlen] = b64[self.Bh[i].H % 64];
self.Bh[i].Halfdigest = b64[self.Bh[i].Halfh % 64];
if(self.Bh[i].Dlen < SPAMSUM_LENGTH - 1)
{
/* We can have a problem with the tail overflowing. The
@@ -208,45 +250,25 @@ namespace DiscImageChef.Checksums
* last few pieces of the message into a single piece
* */
self.Bh[i].Digest[++self.Bh[i].Dlen] = 0;
self.Bh[i].H = HASH_INIT;
self.Bh[i].H = HASH_INIT;
if(self.Bh[i].Dlen >= SPAMSUM_LENGTH / 2) continue;
self.Bh[i].Halfh = HASH_INIT;
self.Bh[i].Halfh = HASH_INIT;
self.Bh[i].Halfdigest = 0;
}
else fuzzy_try_reduce_blockhash();
}
}
/// <summary>
/// Updates the hash with data.
/// </summary>
/// <param name="data">Data buffer.</param>
/// <param name="len">Length of buffer to hash.</param>
public void Update(byte[] data, uint len)
{
self.TotalSize += len;
for(int i = 0; i < len; i++) fuzzy_engine_step(data[i]);
}
/// <summary>
/// Updates the hash with data.
/// </summary>
/// <param name="data">Data buffer.</param>
public void Update(byte[] data)
{
Update(data, (uint)data.Length);
}
// CLAUNIA: Flags seems to never be used in ssdeep, so I just removed it for code simplicity
uint FuzzyDigest(out byte[] result)
{
StringBuilder sb = new StringBuilder();
uint bi = self.Bhstart;
uint h = roll_sum();
int i, resultOff;
int remain = (int)(FUZZY_MAX_RESULT - 1); /* Exclude terminating '\0'. */
result = new byte[FUZZY_MAX_RESULT];
uint bi = self.Bhstart;
uint h = roll_sum();
int i, resultOff;
int remain = (int)(FUZZY_MAX_RESULT - 1); /* Exclude terminating '\0'. */
result = new byte[FUZZY_MAX_RESULT];
/* Verify that our elimination was not overeager. */
if(!(bi == 0 || (ulong)SSDEEP_BS(bi) / 2 * SPAMSUM_LENGTH < self.TotalSize))
throw new Exception("Assertion failed");
@@ -259,6 +281,7 @@ namespace DiscImageChef.Checksums
++bi;
if(bi >= NUM_BLOCKHASHES) throw new OverflowException("The input exceeds data types.");
}
/* Adapt blocksize guess to actual digest length. */
while(bi >= self.Bhend) --bi;
while(bi > self.Bhstart && self.Bh[bi].Dlen < SPAMSUM_LENGTH / 2) --bi;
@@ -282,14 +305,15 @@ namespace DiscImageChef.Checksums
Array.Copy(self.Bh[bi].Digest, 0, result, resultOff, i);
resultOff += i;
remain -= i;
remain -= i;
if(h != 0)
{
if(remain <= 0) throw new Exception("Assertion failed");
result[resultOff] = b64[self.Bh[bi].H % 64];
if(i < 3 || result[resultOff] != result[resultOff - 1] || result[resultOff] != result[resultOff - 2] ||
result[resultOff] != result[resultOff - 3])
if(i < 3 || result[resultOff] != result[resultOff - 1] ||
result[resultOff] != result[resultOff - 2] ||
result[resultOff] != result[resultOff - 3])
{
++resultOff;
--remain;
@@ -300,8 +324,9 @@ namespace DiscImageChef.Checksums
if(remain <= 0) throw new Exception("Assertion failed");
result[resultOff] = self.Bh[bi].Digest[i];
if(i < 3 || result[resultOff] != result[resultOff - 1] || result[resultOff] != result[resultOff - 2] ||
result[resultOff] != result[resultOff - 3])
if(i < 3 || result[resultOff] != result[resultOff - 1] ||
result[resultOff] != result[resultOff - 2] ||
result[resultOff] != result[resultOff - 3])
{
++resultOff;
--remain;
@@ -320,16 +345,17 @@ namespace DiscImageChef.Checksums
Array.Copy(self.Bh[bi].Digest, 0, result, resultOff, i);
resultOff += i;
remain -= i;
remain -= i;
if(h != 0)
{
if(remain <= 0) throw new Exception("Assertion failed");
h = self.Bh[bi].Halfh;
h = self.Bh[bi].Halfh;
result[resultOff] = b64[h % 64];
if(i < 3 || result[resultOff] != result[resultOff - 1] ||
result[resultOff] != result[resultOff - 2] || result[resultOff] != result[resultOff - 3])
if(i < 3 || result[resultOff] != result[resultOff - 1] ||
result[resultOff] != result[resultOff - 2] ||
result[resultOff] != result[resultOff - 3])
{
++resultOff;
--remain;
@@ -343,8 +369,9 @@ namespace DiscImageChef.Checksums
if(remain <= 0) throw new Exception("Assertion failed");
result[resultOff] = (byte)i;
if(i < 3 || result[resultOff] != result[resultOff - 1] ||
result[resultOff] != result[resultOff - 2] || result[resultOff] != result[resultOff - 3])
if(i < 3 || result[resultOff] != result[resultOff - 1] ||
result[resultOff] != result[resultOff - 2] ||
result[resultOff] != result[resultOff - 3])
{
++resultOff;
--remain;
@@ -355,7 +382,7 @@ namespace DiscImageChef.Checksums
else if(h != 0)
{
if(self.Bh[bi].Dlen != 0) throw new Exception("Assertion failed");
if(remain <= 0) throw new Exception("Assertion failed");
if(remain <= 0) throw new Exception("Assertion failed");
result[resultOff++] = b64[self.Bh[bi].H % 64];
/* No need to bother with FUZZY_FLAG_ELIMSEQ, because this
@@ -367,25 +394,6 @@ namespace DiscImageChef.Checksums
return 0;
}
/// <summary>
/// Returns a byte array of the hash value.
/// </summary>
public byte[] Final()
{
// SpamSum does not have a binary representation, or so it seems
throw new NotImplementedException("SpamSum does not have a binary representation.");
}
/// <summary>
/// Returns a base64 representation of the hash value.
/// </summary>
public string End()
{
FuzzyDigest(out byte[] result);
return CToString(result);
}
/// <summary>
/// Gets the hash of a file
/// </summary>
@@ -417,7 +425,6 @@ namespace DiscImageChef.Checksums
public static string Data(byte[] data, uint len, out byte[] hash)
{
SpamSumContext fuzzyContext = new SpamSumContext();
fuzzyContext.Init();
fuzzyContext.Update(data, len);
@@ -469,8 +476,8 @@ namespace DiscImageChef.Checksums
* output hash to stay compatible with ssdeep output. */
struct BlockhashContext
{
public uint H;
public uint Halfh;
public uint H;
public uint Halfh;
public byte[] Digest;
// SPAMSUM_LENGTH
public byte Halfdigest;
@@ -479,11 +486,11 @@ namespace DiscImageChef.Checksums
struct FuzzyState
{
public uint Bhstart;
public uint Bhend;
public uint Bhstart;
public uint Bhend;
public BlockhashContext[] Bh;
//NUM_BLOCKHASHES
public ulong TotalSize;
public ulong TotalSize;
public RollState Roll;
}
}