1 files changed, 49 insertions, 0 deletions
diff --git a/examples/custom_mutators/simple_mutator.c b/examples/custom_mutators/simple_mutator.c
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+++ b/examples/custom_mutators/simple_mutator.c
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+/*
+  Simple Custom Mutator for AFL
+
+  Written by Khaled Yakdan <yakdan@code-intelligence.de>
+
+  This a simple mutator that assumes that the generates messages starting with
+  one of the three strings GET, PUT, or DEL followed by a payload. The mutator
+  randomly selects a commend and mutates the payload of the seed provided as
+  input.
+*/
+
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+
+static const char *commands[] = {
+
+    "GET",
+    "PUT",
+    "DEL",
+
+};
+
+static size_t data_size = 100;
+
+size_t afl_custom_mutator(uint8_t *data, size_t size, uint8_t *mutated_out,
+                          size_t max_size, unsigned int seed) {
+
+  // Seed the PRNG
+  srand(seed);
+
+  // Make sure that the packet size does not exceed the maximum size expected by
+  // the fuzzer
+  size_t mutated_size = data_size <= max_size ? data_size : max_size;
+
+  // Randomly select a command string to add as a header to the packet
+  memcpy(mutated_out, commands[rand() % 3], 3);
+
+  // Mutate the payload of the packet
+  for (int i = 3; i < mutated_size; i++) {
+
+    mutated_out[i] = (data[i] + rand() % 10) & 0xff;
+
+  }
+
+  return mutated_size;
+
+}
+