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https://github.com/UglyToad/PdfPig.git
synced 2025-08-20 09:37:44 +08:00
- Fix of Stream invalid Length issue (causing stream data not being fully read).
- Improve Stream read performance by simplifying TryReadStream(), avoiding use of MemoryStream, with benefice of already existing Memory Span of "inputBytes"
This commit is contained in:
Sylvain Bruyere
parent
d86c2f44f0
commit
bb5a757e8c
@ -1,4 +1,7 @@
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namespace UglyToad.PdfPig.Tokenization.Scanner
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//TODO: https://blog.cerbero.io/cve-2010-0188-pdfformtiff/
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// https://beta-v1.malva.re/file/f1e966769e544b4b67f203ca51909b9d/report
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namespace UglyToad.PdfPig.Tokenization.Scanner
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{
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using System;
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using System.Collections.Generic;
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@ -7,6 +10,7 @@
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using System.Globalization;
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using System.IO;
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using System.Linq;
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using System.Text;
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using System.Text.RegularExpressions;
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using Core;
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using Encryption;
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@ -320,7 +324,7 @@
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int endStreamPosition = 0;
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int commonPartPosition = 0;
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const string commonPart = "end";
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const string endWordPart = "end";
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const string streamPart = "stream";
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const string objPart = "obj";
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@ -330,151 +334,130 @@
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return true;
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}
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// Track any 'endobj' or 'endstream' operators we see.
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var observedEndLocations = new List<PossibleStreamEndLocation>();
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long streamDataStart = inputBytes.CurrentOffset;
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// Begin reading the stream.
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using (var memoryStream = new MemoryStream())
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using (var binaryWrite = new BinaryWriter(memoryStream))
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PossibleStreamEndLocation? possibleEndLocation = null;
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while (inputBytes.MoveNext())
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{
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while (inputBytes.MoveNext())
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if (length.HasValue && read == length)
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{
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if (length.HasValue && read == length)
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{
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// TODO: read ahead and check we're at the end...
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// break;
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}
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// TODO: read ahead and check we're at the end...
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// break;
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}
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// We are reading 'end' (possibly).
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if (commonPartPosition < commonPart.Length && inputBytes.CurrentByte == commonPart[commonPartPosition])
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// We are reading 'end' (possibly).
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if (commonPartPosition < endWordPart.Length && inputBytes.CurrentByte == endWordPart[commonPartPosition])
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{
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commonPartPosition++;
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}
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else if (commonPartPosition == endWordPart.Length)
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{
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// We are reading 'stream' after 'end'
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if (inputBytes.CurrentByte == streamPart[endStreamPosition])
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{
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commonPartPosition++;
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}
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else if (commonPartPosition == commonPart.Length)
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{
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// We are reading 'stream' after 'end'
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if (inputBytes.CurrentByte == streamPart[endStreamPosition])
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endObjPosition = 0;
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endStreamPosition++;
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// We've finished reading 'endstream', add it to the end tokens we've seen.
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if (endStreamPosition == streamPart.Length && (!inputBytes.MoveNext() || ReadHelper.IsWhitespace(inputBytes.CurrentByte)))
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{
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endObjPosition = 0;
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endStreamPosition++;
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var token = new PossibleStreamEndLocation(inputBytes.CurrentOffset - OperatorToken.EndStream.Data.Length, OperatorToken.EndStream);
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// We've finished reading 'endstream', add it to the end tokens we've seen.
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if (endStreamPosition == streamPart.Length && (!inputBytes.MoveNext() || ReadHelper.IsWhitespace(inputBytes.CurrentByte)))
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possibleEndLocation = token;
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//observedEndLocations.Add(token);
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if (length.HasValue && read > length)
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{
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var token = new PossibleStreamEndLocation(inputBytes.CurrentOffset - OperatorToken.EndStream.Data.Length, OperatorToken.EndStream);
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observedEndLocations.Add(token);
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if (length.HasValue && read > length)
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{
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break;
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}
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endStreamPosition = 0;
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break;
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}
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}
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else if (inputBytes.CurrentByte == objPart[endObjPosition])
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{
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// We are reading 'obj' after 'end'
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endStreamPosition = 0;
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endObjPosition++;
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// We have finished reading 'endobj'.
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if (endObjPosition == objPart.Length)
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{
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// If we saw an 'endstream' or 'endobj' previously we've definitely hit the end now.
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if (observedEndLocations.Count > 0)
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{
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var lastEndToken = observedEndLocations[observedEndLocations.Count - 1];
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inputBytes.Seek(lastEndToken.Offset + lastEndToken.Type.Data.Length + 1);
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break;
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}
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var token = new PossibleStreamEndLocation(inputBytes.CurrentOffset - OperatorToken.EndObject.Data.Length, OperatorToken.EndObject);
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observedEndLocations.Add(token);
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if (read > length)
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{
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break;
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}
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}
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}
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else
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{
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// We were reading 'end' but then we had a character mismatch.
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// Reset all the counters.
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}
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else if (inputBytes.CurrentByte == objPart[endObjPosition])
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{
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// We are reading 'obj' after 'end'
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endStreamPosition = 0;
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endObjPosition = 0;
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commonPartPosition = 0;
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endStreamPosition = 0;
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endObjPosition++;
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// We have finished reading 'endobj'.
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if (endObjPosition == objPart.Length)
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{
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// If we saw an 'endstream' or 'endobj' previously we've definitely hit the end now.
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if (possibleEndLocation != null)
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{
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var lastEndToken = possibleEndLocation.Value; //observedEndLocations[observedEndLocations.Count - 1];
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inputBytes.Seek(lastEndToken.Offset + lastEndToken.Type.Data.Length + 1);
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//streamDataEnd = lastEndToken.Offset + lastEndToken.Type.Data.Length + 1;
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break;
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}
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var token = new PossibleStreamEndLocation(inputBytes.CurrentOffset - OperatorToken.EndObject.Data.Length, OperatorToken.EndObject);
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possibleEndLocation = token;
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if (read > length)
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{
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break;
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}
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}
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}
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else
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{
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// For safety reset every counter in case we had a partial read.
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// We were reading 'end' but then we had a character mismatch.
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// Reset all the counters.
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endStreamPosition = 0;
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endObjPosition = 0;
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commonPartPosition = (inputBytes.CurrentByte == commonPart[0]) ? 1 : 0;
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commonPartPosition = 0;
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}
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binaryWrite.Write(inputBytes.CurrentByte);
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read++;
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}
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binaryWrite.Flush();
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if (observedEndLocations.Count == 0)
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{
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return false;
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}
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memoryStream.Seek(0, SeekOrigin.Begin);
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if (length.HasValue && memoryStream.Length >= length)
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{
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// Use the declared length to copy just the data we want.
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byte[] data = new byte[length.Value];
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memoryStream.Read(data, 0, (int)length.Value);
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stream = new StreamToken(streamDictionaryToken, data);
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}
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else
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{
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// Work out where '\r\nendobj' or '\r\nendstream' occurs and read everything up to that.
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var lastEnd = observedEndLocations[observedEndLocations.Count - 1];
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// For safety reset every counter in case we had a partial read.
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var dataLength = lastEnd.Offset - startDataOffset;
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var current = inputBytes.CurrentOffset;
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// 3 characters, 'e', '\n' and possibly '\r'
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inputBytes.Seek(lastEnd.Offset - 3);
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inputBytes.MoveNext();
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if (inputBytes.CurrentByte == '\r')
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{
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dataLength -= 3;
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}
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else
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{
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dataLength -= 2;
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}
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inputBytes.Seek(current);
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byte[] data = new byte[dataLength];
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memoryStream.Read(data, 0, (int)dataLength);
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stream = new StreamToken(streamDictionaryToken, data);
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endStreamPosition = 0;
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endObjPosition = 0;
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commonPartPosition = (inputBytes.CurrentByte == endWordPart[0]) ? 1 : 0;
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}
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read++;
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}
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long streamDataEnd = inputBytes.CurrentOffset + 1;
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if (possibleEndLocation == null)
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return false;
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var lastEnd = possibleEndLocation;
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var dataLength = lastEnd.Value.Offset - startDataOffset;
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// 3 characters, 'e', '\n' and possibly '\r'
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inputBytes.Seek(lastEnd.Value.Offset - 3);
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inputBytes.MoveNext();
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if (inputBytes.CurrentByte == '\r')
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{
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dataLength -= 3;
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}
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else
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{
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dataLength -= 2;
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}
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Span<byte> data = new byte[dataLength];
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inputBytes.Seek(streamDataStart);
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inputBytes.Read(data);
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inputBytes.Seek(streamDataEnd);
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stream = new StreamToken(streamDictionaryToken, data.ToArray());
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return true;
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}
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