|
| 1 | +#LibBlobStamper |
| 2 | + |
| 3 | +Tool for building structured data out of random input. |
| 4 | + |
| 5 | +When you do fuzzing testing of a project that is complex enoght to have |
| 6 | +syntax parser, and core functionaluty behind it, your fuzzer will probably |
| 7 | +spend a lot of cpu working with syntax parser. Fuzzing syntax parser is a |
| 8 | +good thing, but it does not really help to fuzz core functionality. One of the |
| 9 | +general approaches here may be is to generate such imput data that is syntaxycally |
| 10 | +corrent from the perspectice of syntax parser, and meanwhile totally random form |
| 11 | +the perspective of core functionality. |
| 12 | + |
| 13 | +LibBlobStamper is a tool for building convertors form random binary data |
| 14 | +into random data with required syntax. |
| 15 | + |
| 16 | +LibBlomStamper is written in C++, can be used for genertaing both text data |
| 17 | +with desired sintax, and structured binary data (e.g. C-structures). You can |
| 18 | +build this convertor right into you binary test-unit, so this converstion will be |
| 19 | +opaque both for fuzzer, or DSE-tools. |
| 20 | + |
| 21 | +##Synopsys |
| 22 | + |
| 23 | +```c++ |
| 24 | + Blobblob(data, data_length); |
| 25 | + StampArithm<shortint> stamp; // Stamp that work with arithmetic data (integers, and floats) |
| 26 | + |
| 27 | + std::string s = stamp.ExtractStr(blob); // Get integrer formatted as string |
| 28 | + std::vector<char> vec= stamp.ExtractBin(blob); // Get binary data represeted as byte array |
| 29 | + short int i = stamp.ExtractValue(blob) // Get data represented as a value, that can be used in the code |
| 30 | +``` |
| 31 | +
|
| 32 | +```c++ |
| 33 | +typedef struct // Some complex structure, e.g. complex number |
| 34 | +{ |
| 35 | + float re,im; |
| 36 | +} Complex; |
| 37 | +
|
| 38 | +class StampComplex: public StampBaseStr, public StampBaseV<Complex> // Stamp will have String and Value result representation |
| 39 | +{ |
| 40 | + private: |
| 41 | + StampArithm<float> stamp; // Substamp that is used while building result |
| 42 | + public: |
| 43 | + int maxSize() override {return stamp.maxSize()*2;}; // Should set minimum and maximum ammount of data that can be consumed by stamp |
| 44 | + int minSize() override {return stamp.minSize()*2;}; |
| 45 | + virtual Complex ExtractValue(Blob &blob) override; // Method that constructs "value" representation |
| 46 | + virtual std::string ExtractStr(Blob &blob) override; // Method that constructs "string" representation |
| 47 | +}; |
| 48 | +
|
| 49 | +Complex StampComplex::ExtractValue(Blob &blob) |
| 50 | +{ |
| 51 | + Complex c; |
| 52 | + c.re = stamp.ExtractValue(blob); // Just fill the structure with float values and return it |
| 53 | + c.im = stamp.ExtractValue(blob); |
| 54 | + return c; |
| 55 | +} |
| 56 | +
|
| 57 | +std::string StampComplex::ExtractStr(Blob &blob) |
| 58 | +{ |
| 59 | + std::string s_re = stamp.ExtractStr(blob); // Get numbers as a string |
| 60 | + std::string s_im = stamp.ExtractStr(blob); |
| 61 | + return s_re + " + i" + s_im; // Make result string out of them |
| 62 | +} |
| 63 | +
|
| 64 | +// ......................... Somwhere in main() function .................................... |
| 65 | +
|
| 66 | + Blob blob(data, data_len); |
| 67 | +
|
| 68 | + StampComplex stamp; |
| 69 | + std::string s = stamp.ExtractStr(blob); |
| 70 | + Complex c = stamp.ExtractValue(blob); |
| 71 | +``` |
| 72 | + |
| 73 | +##Basic Definitions |
| 74 | + |
| 75 | +###Blob |
| 76 | + |
| 77 | +Blob is a chunk of binary data that came from fuzzer, or other source, it is |
| 78 | +considered to be random. Stamps consumes data from the Blob, for costructing |
| 79 | +values and for "divination": if Stamp to make some desidion, you get some data from |
| 80 | +the Blob and iterpret it as a "prediction" telling it what to do. E.g. tell the stamp in what |
| 81 | +propotion remaining data should be split for two subordinate Stamps, that can consume any |
| 82 | +ammount of data. Since blob data is considered to be random, you will cover all possible |
| 83 | +proportions in a long run. Blob implemented as C++ onject. |
| 84 | + |
| 85 | +###Stamp |
| 86 | + |
| 87 | +Stamp is a C++ object that knows how to convert some chunk of data into certain structured |
| 88 | +representation. |
| 89 | + |
| 90 | +Basic properties of Stamp from the perspective of data consumation: |
| 91 | + |
| 92 | +* Stamp should know how much data it can consume to produce structured result. Minimanl |
| 93 | +ammount ammount and maximum ammount. These values should be available via minSize() and maxSize() |
| 94 | +methods. |
| 95 | + |
| 96 | +* Stamp is greedy, it consimes as much data as it can. If your blob is long enought, the Stamp will |
| 97 | +byte maxSize() bytes from it. If you want to limit Stamp's appetite, you should wrap it in a Galley |
| 98 | +somehow. |
| 99 | + |
| 100 | +All stamps iherits StampBase class. |
| 101 | + |
| 102 | + |
| 103 | + |
| 104 | + |
| 105 | + |
| 106 | + |
| 107 | + |
| 108 | + |