c-ares/test/ares-fuzz.c

/*
 * General driver to allow command-line fuzzer (i.e. afl) to
 * exercise the libFuzzer entrypoint.
 */

#include <sys/types.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#ifdef WIN32
#include <io.h>
#else
#include <unistd.h>
#endif

#define kMaxAflInputSize (1 << 20)
static unsigned char afl_buffer[kMaxAflInputSize];

#ifdef __AFL_LOOP
/* If we are built with afl-clang-fast, use persistent mode */
#define KEEP_FUZZING(count)  __AFL_LOOP(1000)
#else
/* If we are built with afl-clang, execute each input once */
#define KEEP_FUZZING(count) ((count) < 1)
#endif

/* In ares-test-fuzz.c and ares-test-fuzz-name.c: */
int LLVMFuzzerTestOneInput(const unsigned char *data, unsigned long size);

static void ProcessFile(int fd) {
  int count = read(fd, afl_buffer, kMaxAflInputSize);
  /*
   * Make a copy of the data so that it's not part of a larger
   * buffer (where buffer overflows would go unnoticed).
   */
  unsigned char *copied_data = (unsigned char *)malloc(count);
  memcpy(copied_data, afl_buffer, count);
  LLVMFuzzerTestOneInput(copied_data, count);
  free(copied_data);
}

int main(int argc, char *argv[]) {
  if (argc == 1) {
    int count = 0;
    while (KEEP_FUZZING(count)) {
      ProcessFile(fileno(stdin));
      count++;
    }
  } else {
    int ii;
    for (ii = 1; ii < argc; ++ii) {
      int fd = open(argv[ii], O_RDONLY);
      if (fd < 0) {
        fprintf(stderr, "Failed to open '%s'\n", argv[ii]);
        continue;
      }
      ProcessFile(fd);
      close(fd);
    }
  }
  return 0;
}