1. import java.io.File;
  2. import java.io.IOException;
  3. import java.util.HashMap;
  4. import java.util.Map;
  5. import java.util.regex.Matcher;
  6. import java.util.regex.Pattern;
  8. public class HeaderInstrumenter {
  10. private static final String CONFIG_FILE = "instrument_config.txt";
  11. private static final Pattern HEADER_PATTERN = Pattern.compile("(?i)(.*)\\s+:\\s+(.*)"); // Matches header lines
  13. public static void instrumentHeaders(String filePath, Map<String, String> instrumentationRules) throws IOException {
  14. // Load instrumentation rules from the configuration file
  15. Map<String, String> rules = loadInstrumentationRules(CONFIG_FILE);
  16. if (rules == null) {
  17. System.err.println("Error: Could not load instrumentation rules from " + CONFIG_FILE);
  18. return;
  19. }
  21. File file = new File(filePath);
  23. if (!file.exists()) {
  24. System.err.println("Error: File not found: " + filePath);
  25. return;
  26. }
  28. try (java.io.BufferedReader reader = new java.io.BufferedReader(new java.io.FileReader(file))) {
  29. String line;
  30. java.io.BufferedWriter writer = new java.io.BufferedWriter(new java.io.FileWriter(filePath, false)); // Overwrite the file
  31. while ((line = reader.readLine()) != null) {
  32. Matcher matcher = HEADER_PATTERN.matcher(line);
  33. if (matcher.matches()) {
  34. String headerName = matcher.group(1).trim();
  35. String headerValue = matcher.group(2).trim();
  37. // Apply instrumentation rule if available
  38. if (rules.containsKey(headerName)) {
  39. String replacement = rules.get(headerName);
  40. String newHeaderValue = applyReplacement(headerValue, replacement);
  41. line = matcher.appendReplacement(line, headerName + ": " + newHeaderValue);
  42. }
  43. }
  44. writer.write(line);
  45. }
  46. writer.flush(); // Ensure all data is written
  47. }
  48. }
  50. private static Map<String, String> loadInstrumentationRules(String configFilePath) throws IOException {
  51. Map<String, String> rules = new HashMap<>();
  52. File configFile = new File(configFilePath);
  54. if (!configFile.exists()) {
  55. return null; // Return null if the config file doesn't exist.
  56. }
  58. try (java.io.BufferedReader reader = new java.io.BufferedReader(new java.io.FileReader(configFile))) {
  59. String line;
  60. while ((line = reader.readLine()) != null) {
  61. String[] parts = line.split(":", 2); // Split only at the first colon
  62. if (parts.length == 2) {
  63. String headerName = parts[0].trim();
  64. String replacement = parts[1].trim();
  65. rules.put(headerName, replacement);
  66. }
  67. }
  68. }
  69. return rules;
  70. }
  72. private static String applyReplacement(String value, String replacement) {
  73. //Simple replacement example. Can be expanded.
  74. if (replacement.equals("SANDBOXED")) {
  75. return "SANDBOXED_" + value;
  76. }
  77. return value;
  78. }
  81. public static void main(String[] args) throws IOException {
  82. // Example Usage
  83. String filePath = "input.txt"; // Replace with your file path
  85. //Create dummy input file
  86. File file = new File(filePath);
  87. java.io.FileWriter writer = new java.io.FileWriter(file, "Content-Type: text/html\n" +
  88. "Content-Length: 123\n" +
  89. "X-Custom-Header: original_value\n" +
  90. "AnotherHeader: another_value");
  91. writer.close();
  93. Map<String, String> rules = new HashMap<>();
  94. rules.put("X-Custom-Header", "SANDBOXED");
  95. instrumentHeaders(filePath, rules);
  96. System.out.println("Headers instrumented in " + filePath);
  97. }
  98. }

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