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| 1 | +/// This example demonstrates how to obfuscate the code by renaming all identifiers. |
| 2 | +/// The example goes through the AST and replaces every occurence of a symbol with |
| 3 | +/// a fresh new symbol, generated randomly, while preserving the correctness of the code. |
| 4 | +/// The code uses the Parser and Lexer class to read the contents of a string. The result |
| 5 | +/// is printed to a stream using the Printer class. |
| 6 | + |
| 7 | +#include <unordered_map> |
| 8 | +#include <iostream> |
| 9 | +#include <sstream> |
| 10 | +#include <string> |
| 11 | + |
| 12 | +#include <slang/parser.h> |
| 13 | +#include <slang/sema.h> |
| 14 | +#include <slang/lexer.h> |
| 15 | +#include <slang/logger.h> |
| 16 | +#include <slang/ptr.h> |
| 17 | +#include <slang/ast.h> |
| 18 | +#include <slang/print.h> |
| 19 | + |
| 20 | +using namespace slang; |
| 21 | + |
| 22 | +struct Scope { |
| 23 | + std::unordered_map<std::string, std::string> names; |
| 24 | + std::unordered_set<std::string> new_names; |
| 25 | +}; |
| 26 | + |
| 27 | +struct Obfuscator { |
| 28 | + std::vector<Scope> scopes; |
| 29 | + |
| 30 | + Obfuscator() { push_scope(); } |
| 31 | + |
| 32 | + unsigned int rnd() { |
| 33 | + static int c; |
| 34 | + c = c * 1103515245 + 12345; |
| 35 | + return c; |
| 36 | + } |
| 37 | + |
| 38 | + const std::string* find_name(const std::string& name) { |
| 39 | + for (int i = scopes.size() - 1; i >= 0; i--) { |
| 40 | + auto& s = scopes[i]; |
| 41 | + auto it = s.names.find(name); |
| 42 | + if (it != s.names.end()) { return &it->second; } |
| 43 | + } |
| 44 | + return nullptr; |
| 45 | + } |
| 46 | + |
| 47 | + bool name_exists(const std::string& name) { |
| 48 | + for (int i = scopes.size() - 1; i >= 0; i--) { |
| 49 | + if (scopes[i].new_names.count(name) > 0) return true; |
| 50 | + } |
| 51 | + return false; |
| 52 | + } |
| 53 | + |
| 54 | + std::string new_name(const std::string& name) { |
| 55 | + std::string cur; |
| 56 | + do { |
| 57 | + cur += 'a' + rnd() % 5; |
| 58 | + } while (name_exists(cur)); |
| 59 | + scopes.back().names[name] = cur; |
| 60 | + scopes.back().new_names.emplace(cur); |
| 61 | + return cur; |
| 62 | + } |
| 63 | + |
| 64 | + void pop_scope() { scopes.pop_back(); } |
| 65 | + void push_scope() { scopes.emplace_back(); } |
| 66 | + |
| 67 | + void obfuscate( Ptr<ast::Module>& mod) { |
| 68 | + for (auto& decl : mod->decls()) obfuscate(decl); |
| 69 | + } |
| 70 | + |
| 71 | + void obfuscate( Ptr<ast::Decl>& decl) { |
| 72 | + // Look inside function declarations |
| 73 | + if ( auto func_decl = decl-> isa<ast::FunctionDecl>()) { |
| 74 | + // The function can be only a prototype, so there may be no body |
| 75 | + func_decl->set_name(new_name(func_decl->name())); |
| 76 | + push_scope(); |
| 77 | + for (auto& arg : func_decl->args()) obfuscate(arg); |
| 78 | + if (func_decl->body()) obfuscate(func_decl->body()); |
| 79 | + pop_scope(); |
| 80 | + } else if ( auto var_decl = decl-> isa<ast::VariableDecl>()) { |
| 81 | + obfuscate(var_decl->type()); |
| 82 | + for (auto& var : var_decl->vars()) obfuscate(var); |
| 83 | + } |
| 84 | + } |
| 85 | + |
| 86 | + void obfuscate( Ptr<ast::Type>& type) { |
| 87 | + if ( auto named_type = type-> isa<ast::NamedType>()) { |
| 88 | + auto name = find_name(named_type->name()); |
| 89 | + if (name) named_type->set_name(*name); |
| 90 | + } else if ( auto compound = type-> isa<ast::CompoundType>()) { |
| 91 | + compound->set_name(new_name(compound->name())); |
| 92 | + for (auto& field : compound->fields()) { |
| 93 | + obfuscate(field->type()); |
| 94 | + for (auto& var : field->vars()) obfuscate(var); |
| 95 | + } |
| 96 | + } |
| 97 | + } |
| 98 | + |
| 99 | + void obfuscate( Ptr<ast::Arg>& arg) { |
| 100 | + obfuscate(arg->type()); |
| 101 | + arg->set_name(new_name(arg->name())); |
| 102 | + } |
| 103 | + |
| 104 | + void obfuscate( Ptr<ast::Variable>& var) { |
| 105 | + obfuscate(var->init()); |
| 106 | + var->set_name(new_name(var->name())); |
| 107 | + } |
| 108 | + |
| 109 | + void obfuscate( Ptr<ast::StmtList>& list) { |
| 110 | + push_scope(); |
| 111 | + for (auto& stmt : list->stmts()) obfuscate(stmt); |
| 112 | + pop_scope(); |
| 113 | + } |
| 114 | + |
| 115 | + void obfuscate( Ptr<ast::Stmt>& stmt) { |
| 116 | + if ( auto list = stmt-> isa<ast::StmtList>()) { |
| 117 | + // List of statements |
| 118 | + push_scope(); |
| 119 | + for (auto& stmt : list->stmts()) obfuscate(stmt); |
| 120 | + pop_scope(); |
| 121 | + } else if ( auto if_stmt = stmt-> isa<ast::IfStmt>()) { |
| 122 | + // If statements |
| 123 | + obfuscate(if_stmt->cond()); |
| 124 | + obfuscate(if_stmt->if_true()); |
| 125 | + obfuscate(if_stmt->if_false()); |
| 126 | + } else if ( auto switch_stmt = stmt-> isa<ast::SwitchStmt>()) { |
| 127 | + // Switch statements |
| 128 | + obfuscate(switch_stmt->expr()); |
| 129 | + obfuscate(switch_stmt->list()); |
| 130 | + } else if ( auto for_stmt = stmt-> isa<ast::ForLoopStmt>()) { |
| 131 | + // For loops |
| 132 | + obfuscate(for_stmt->init()); |
| 133 | + obfuscate(for_stmt->iter()); |
| 134 | + obfuscate(for_stmt->cond()); |
| 135 | + obfuscate(for_stmt->body()); |
| 136 | + } else if ( auto loop_stmt = stmt-> isa<ast::LoopStmt>()) { |
| 137 | + // Other loops: while and do...while |
| 138 | + obfuscate(loop_stmt->cond()); |
| 139 | + obfuscate(loop_stmt->body()); |
| 140 | + } else if ( auto expr_stmt = stmt-> isa<ast::ExprStmt>()) { |
| 141 | + // Expressions |
| 142 | + obfuscate(expr_stmt->expr()); |
| 143 | + } else if ( auto decl_stmt = stmt-> isa<ast::DeclStmt>()) { |
| 144 | + // Declarations |
| 145 | + obfuscate(decl_stmt->decl()); |
| 146 | + } else if ( auto ret_stmt = stmt-> isa<ast::ReturnStmt>()) { |
| 147 | + // Return statements |
| 148 | + obfuscate(ret_stmt->value()); |
| 149 | + } |
| 150 | + } |
| 151 | + |
| 152 | + void obfuscate( Ptr<ast::LoopCond>& cond) { |
| 153 | + if (cond->expr()) obfuscate(cond->expr()); |
| 154 | + } |
| 155 | + |
| 156 | + void obfuscate( Ptr<ast::Expr>& expr) { |
| 157 | + if ( auto bin_op = expr-> isa<ast::BinOpExpr>()) { |
| 158 | + // First, descend in the tree |
| 159 | + obfuscate(bin_op->left()); |
| 160 | + obfuscate(bin_op->right()); |
| 161 | + } else if ( auto un_op = expr-> isa<ast::UnOpExpr>()) { |
| 162 | + // Unary operation |
| 163 | + obfuscate(un_op->operand()); |
| 164 | + } else if ( auto assign_op = expr-> isa<ast::AssignOpExpr>()) { |
| 165 | + // Operation with assignment |
| 166 | + obfuscate(assign_op->left()); |
| 167 | + obfuscate(assign_op->right()); |
| 168 | + } else if ( auto cond = expr-> isa<ast::CondExpr>()) { |
| 169 | + // Ternary operator |
| 170 | + obfuscate(cond->cond()); |
| 171 | + obfuscate(cond->if_true()); |
| 172 | + obfuscate(cond->if_false()); |
| 173 | + } else if ( auto call = expr-> isa<ast::CallExpr>()) { |
| 174 | + if (call->function()) obfuscate(call->function()); |
| 175 | + if (call->constructor()) obfuscate(call->constructor()); |
| 176 | + for (auto& arg : call->args()) obfuscate(arg); |
| 177 | + } else if ( auto index = expr-> isa<ast::IndexExpr>()) { |
| 178 | + obfuscate(index->left()); |
| 179 | + obfuscate(index->index()); |
| 180 | + } else if ( auto list = expr-> isa<ast::ExprList>()) { |
| 181 | + for (auto& expr : list->exprs()) obfuscate(expr); |
| 182 | + } else if ( auto ident = expr-> isa<ast::IdentExpr>()) { |
| 183 | + // Find the obfuscated version of the identifier if it exists |
| 184 | + auto name = find_name(ident->ident()); |
| 185 | + if (name) ident->set_ident(*name); |
| 186 | + } |
| 187 | + } |
| 188 | +}; |
| 189 | + |
| 190 | +int main(int argc, char** argv) { |
| 191 | + std::string glsl = |
| 192 | +R"( |
| 193 | +struct Node { |
| 194 | + int left, right; |
| 195 | + float value; |
| 196 | +}; |
| 197 | +float pow(float x, int i) { |
| 198 | + if (i == 0) return 1.0; |
| 199 | + else if (i % 2 == 0) return x * pow(x, i - 1); |
| 200 | + else return pow(x, i / 2); |
| 201 | +} |
| 202 | +float test() { |
| 203 | + float unit = 42.0; |
| 204 | + int array[10]; |
| 205 | + Node element; |
| 206 | + for (int i = 0; i < 10; i++) { |
| 207 | + array[i] = pow(unit, i); |
| 208 | + } |
| 209 | +} |
| 210 | +)"; |
| 211 | + std::istringstream is(glsl); |
| 212 | + |
| 213 | + // Create a logger object to report errors |
| 214 | + Logger log("inline_string.glsl"); |
| 215 | + // Create a set of keywords |
| 216 | + Keywords keys; |
| 217 | + keys.add_all_keywords(); |
| 218 | + // Create a lexer to generate a stream of tokens |
| 219 | + Lexer lex(is, keys, log); |
| 220 | + // Create a semantic analyser (type checker) object |
| 221 | + Sema sema(log); |
| 222 | + // Create a parser object |
| 223 | + Parser parser([&] { return lex.lex(); }, sema, log); |
| 224 | + |
| 225 | + auto module = parser.parse(); |
| 226 | + |
| 227 | + Obfuscator obfuscator; |
| 228 | + obfuscator.obfuscate(module); |
| 229 | + |
| 230 | + std::ostringstream out; |
| 231 | + Printer printer(out, " ", 0, false, false); |
| 232 | + module->print(printer); |
| 233 | + |
| 234 | + std::cout << out.str(); |
| 235 | + |
| 236 | + return out.str() == |
| 237 | +R"(struct a { |
| 238 | + int e, d; |
| 239 | + float c; |
| 240 | +}; |
| 241 | +float db(float ea, int b) { |
| 242 | + if (b == 0) return 1.0; |
| 243 | + else if (b % 2 == 0) return ea * db(ea, b - 1); |
| 244 | + else return db(ea, b / 2); |
| 245 | +} |
| 246 | +float aa() { |
| 247 | + float ea = 42.0; |
| 248 | + int cb[10]; |
| 249 | + a da; |
| 250 | + for (int eaa = 0; eaa < 10; eaa++) { |
| 251 | + cb[eaa] = db(ea, eaa); |
| 252 | + } |
| 253 | +} |
| 254 | +)" ? 0 : 1; |
| 255 | +} |
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