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Optimize rawData QrCodeData constructor and improve input validation #709

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Merged
Shane32 merged 1 commit into from
Oct 31, 2026
Merged

Optimize rawData QrCodeData constructor and improve input validation #709

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47 changes: 27 additions & 20 deletions QRCoder/QRCodeData.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -55,7 +55,7 @@ public QRCodeData(string pathToRawData, Compression compressMode) : this(File.Re
/// <param name="compressMode">The compression mode used for the raw data.</param>
public QRCodeData(byte[] rawData, Compression compressMode)
{
//Decompress
// Decompress
if (compressMode == Compression.Deflate)
{
using var input = new MemoryStream(rawData);
Expand All @@ -77,46 +77,53 @@ public QRCodeData(byte[] rawData, Compression compressMode)
rawData = output.ToArray();
}

if (rawData.Length < 5)
const int HeaderLength = 5; // 4 bytes signature + 1 byte side length

if (rawData.Length < HeaderLength)
throw new InvalidDataException("Invalid raw data file. File too short.");
if (rawData[0] != 0x51 || rawData[1] != 0x52 || rawData[2] != 0x52)

if (rawData[0] != 0x51 || rawData[1] != 0x52 || rawData[2] != 0x52 || rawData[3] != 0)
throw new InvalidDataException("Invalid raw data file. Filetype doesn't match \"QRR\".");

// Set QR code version from side length (includes 8-module quiet zone)
var sideLen = (int)rawData[4];
int sideLen = rawData[4];
if (sideLen < 29) // Micro QR: sideLen = 19 + 2*(m-1), m in [1..4] -> versions -1..-4
{
if (((sideLen - 19) & 1) != 0)
if (sideLen < 19 || sideLen > 25 || (sideLen & 1) == 0)
throw new InvalidDataException("Invalid raw data file. Side length not valid for Micro QR.");
var m = ((sideLen - 19) / 2) + 1;
Version = -m;

Version = -((sideLen - 17) >>> 1);
}
else // Standard QR: sideLen = 29 + 4*(v-1), v in [1..40]
{
if (((sideLen - 29) % 4) != 0)
if (sideLen > 185 || (sideLen & 3) != 1)
throw new InvalidDataException("Invalid raw data file. Side length not valid for QR.");
Version = ((sideLen - 29) / 4) + 1;

Version = (sideLen - 25) >>> 2;
}

//Unpack
var modules = new Queue<bool>(8 * (rawData.Length - 5));
for (int j = 5; j < rawData.Length; j++)
int byteLength = (sideLen * sideLen + 7) >>> 3;
if (rawData.Length < 5 + byteLength)
{
var b = rawData[j];
for (int i = 7; i >= 0; i--)
{
modules.Enqueue((b & (1 << i)) != 0);
}
throw new InvalidDataException("Invalid raw data file. Not enough data.");
Comment on lines +105 to +108
}

//Build module matrix
// Build module matrix
ModuleMatrix = new List<BitArray>(sideLen);
int bitIndex = HeaderLength * 8; // Skip header bytes

for (int y = 0; y < sideLen; y++)
{
ModuleMatrix.Add(new BitArray(sideLen));
var row = new BitArray(sideLen);
ModuleMatrix.Add(row);

for (int x = 0; x < sideLen; x++)
{
ModuleMatrix[y][x] = modules.Dequeue();
int byteIndex = bitIndex >>> 3;
int mask = 1 << (~bitIndex & 7);
row[x] = (rawData[byteIndex] & mask) != 0;

bitIndex++;
}
}
}
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