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-rw-r--r--utils/afl_frida/GNUmakefile23
-rw-r--r--utils/afl_frida/Makefile2
-rw-r--r--utils/afl_frida/README.md34
-rw-r--r--utils/afl_frida/afl-frida.c397
-rw-r--r--utils/afl_frida/afl-frida.h53
-rw-r--r--utils/afl_frida/android/README.md1
-rw-r--r--utils/afl_frida/android/frida-gum-example.c130
-rw-r--r--utils/afl_frida/libtestinstr.c35
8 files changed, 675 insertions, 0 deletions
diff --git a/utils/afl_frida/GNUmakefile b/utils/afl_frida/GNUmakefile
new file mode 100644
index 00000000..8b56415b
--- /dev/null
+++ b/utils/afl_frida/GNUmakefile
@@ -0,0 +1,23 @@
+ifdef DEBUG
+  OPT=-O0 -D_DEBUG=\"1\"
+else
+  OPT=-O3 -funroll-loops
+endif
+
+all:	afl-frida libtestinstr.so
+
+libfrida-gum.a:
+	@echo Download and extract frida-gum-devkit-VERSION-PLATFORM.tar.xz for your platform from https://github.com/frida/frida/releases/latest
+	@exit 1
+	
+afl-frida:	afl-frida.c libfrida-gum.a
+	$(CC) -g $(OPT) -o afl-frida -Wno-format -Wno-pointer-sign -I. -fpermissive -fPIC afl-frida.c ../../afl-compiler-rt.o libfrida-gum.a -ldl -lresolv -pthread
+
+libtestinstr.so:        libtestinstr.c
+	$(CC) -g -O0 -fPIC -o libtestinstr.so -shared libtestinstr.c
+
+clean:
+	rm -f afl-frida *~ core *.o libtestinstr.so
+
+deepclean: clean
+	rm -f libfrida-gum.a frida-gum*
diff --git a/utils/afl_frida/Makefile b/utils/afl_frida/Makefile
new file mode 100644
index 00000000..0b306dde
--- /dev/null
+++ b/utils/afl_frida/Makefile
@@ -0,0 +1,2 @@
+all:
+	@echo please use GNU make, thanks!
diff --git a/utils/afl_frida/README.md b/utils/afl_frida/README.md
new file mode 100644
index 00000000..68b62009
--- /dev/null
+++ b/utils/afl_frida/README.md
@@ -0,0 +1,34 @@
+# afl-frida - faster fuzzing of binary-only libraries
+
+## Introduction
+
+afl-frida is an example skeleton file which can easily be used to fuzz
+a closed source library.
+
+It requires less memory and is x5-10 faster than qemu_mode but does not
+provide interesting features like compcov or cmplog.
+
+## How-to
+
+### Modify afl-frida.c
+
+Read and modify afl-frida.c then `make`.
+To adapt afl-frida.c to your needs, read the header of the file and then
+search and edit the `STEP 1`, `STEP 2` and `STEP 3` locations.
+
+### Fuzzing
+
+Example (after modifying afl-frida.c to your needs and compile it):
+```
+LD_LIBRARY_PATH=/path/to/the/target/library/ afl-fuzz -i in -o out -- ./afl-frida
+```
+(or even remote via afl-network-proxy).
+
+# Speed and stability
+
+The speed is very good, about x12 of fork() qemu_mode.
+However the stability is low. Reason is currently unknown.
+
+# Background
+
+This code is copied for a larger part from https://github.com/meme/hotwax
diff --git a/utils/afl_frida/afl-frida.c b/utils/afl_frida/afl-frida.c
new file mode 100644
index 00000000..711d8f33
--- /dev/null
+++ b/utils/afl_frida/afl-frida.c
@@ -0,0 +1,397 @@
+/*
+   american fuzzy lop++ - afl-frida skeleton example
+   -------------------------------------------------
+
+   Copyright 2020 AFLplusplus Project. All rights reserved.
+
+   Written mostly by meme -> https://github.com/meme/hotwax
+
+   Modifications by Marc Heuse <mh@mh-sec.de>
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at:
+
+   http://www.apache.org/licenses/LICENSE-2.0
+
+   HOW-TO
+   ======
+
+   You only need to change the following:
+
+   1. set the defines and function call parameters.
+   2. dl load the library you want to fuzz, lookup the functions you need
+      and setup the calls to these.
+   3. in the while loop you call the functions in the necessary order -
+      incl the cleanup. the cleanup is important!
+
+   Just look these steps up in the code, look for "// STEP x:"
+
+*/
+
+#include <stdio.h>
+#include <stdint.h>
+#include <unistd.h>
+#include <stdint.h>
+#include <stddef.h>
+#include <sys/shm.h>
+#include <dlfcn.h>
+
+#ifdef __APPLE__
+  #include <mach/mach.h>
+  #include <mach-o/dyld_images.h>
+#else
+  #include <sys/wait.h>
+  #include <sys/personality.h>
+#endif
+
+int debug = 0;
+
+// STEP 1:
+
+// The presets are for the example libtestinstr.so:
+
+/* What is the name of the library to fuzz */
+#define TARGET_LIBRARY "libtestinstr.so"
+
+/* What is the name of the function to fuzz */
+#define TARGET_FUNCTION "testinstr"
+
+/* here you need to specify the parameter for the target function */
+static void *(*o_function)(uint8_t *, int);
+
+// END STEP 1
+
+#include "frida-gum.h"
+
+void instr_basic_block(GumStalkerIterator *iterator, GumStalkerOutput *output,
+                       gpointer user_data);
+void afl_setup(void);
+void afl_start_forkserver(void);
+int  __afl_persistent_loop(unsigned int max_cnt);
+
+#include "../../config.h"
+
+// Shared memory fuzzing.
+int                   __afl_sharedmem_fuzzing = 1;
+extern unsigned int * __afl_fuzz_len;
+extern unsigned char *__afl_fuzz_ptr;
+
+// Notify AFL about persistent mode.
+static volatile char AFL_PERSISTENT[] = "##SIG_AFL_PERSISTENT##\0";
+int                  __afl_persistent_loop(unsigned int);
+
+// Notify AFL about deferred forkserver.
+static volatile char AFL_DEFER_FORKSVR[] = "##SIG_AFL_DEFER_FORKSRV##\0";
+void                 __afl_manual_init();
+
+// Because we do our own logging.
+extern uint8_t *        __afl_area_ptr;
+static __thread guint64 previous_pc;
+
+// Frida stuff below.
+typedef struct {
+
+  GumAddress base_address;
+  guint64    code_start, code_end;
+  GumAddress current_log_impl;
+  uint64_t   afl_prev_loc;
+
+} range_t;
+
+inline static void afl_maybe_log(guint64 current_pc) {
+
+  // fprintf(stderr, "PC: %p ^ %p\n", current_pc, previous_pc);
+
+  current_pc = (current_pc >> 4) ^ (current_pc << 8);
+  current_pc &= MAP_SIZE - 1;
+
+  __afl_area_ptr[current_pc ^ previous_pc]++;
+  previous_pc = current_pc >> 1;
+
+}
+
+#if GUM_NATIVE_CPU == GUM_CPU_AMD64
+
+static const guint8 afl_maybe_log_code[] = {
+
+    0x9c,  // pushfq
+    0x50,  // push rax
+    0x51,  // push rcx
+    0x52,  // push rdx
+    0x56,  // push rsi
+
+    0x89, 0xf8,                                // mov eax, edi
+    0xc1, 0xe0, 0x08,                          // shl eax, 8
+    0xc1, 0xef, 0x04,                          // shr edi, 4
+    0x31, 0xc7,                                // xor edi, eax
+    0x0f, 0xb7, 0xc7,                          // movzx eax, di
+    0x48, 0x8d, 0x0d, 0x30, 0x00, 0x00, 0x00,  // lea rcx, sym._afl_area_ptr_ptr
+    0x48, 0x8b, 0x09,                          // mov rcx, qword [rcx]
+    0x48, 0x8b, 0x09,                          // mov rcx, qword [rcx]
+    0x48, 0x8d, 0x15, 0x1b, 0x00, 0x00, 0x00,  // lea rdx, sym._afl_prev_loc_ptr
+    0x48, 0x8b, 0x32,                          // mov rsi, qword [rdx]
+    0x48, 0x8b, 0x36,                          // mov rsi, qword [rsi]
+    0x48, 0x31, 0xc6,                          // xor rsi, rax
+    0xfe, 0x04, 0x31,                          // inc byte [rcx + rsi]
+
+    0x48, 0xd1, 0xe8,  // shr rax, 1
+    0x48, 0x8b, 0x0a,  // mov rcx, qword [rdx]
+    0x48, 0x89, 0x01,  // mov qword [rcx], rax
+
+    0x5e,  // pop rsi
+    0x5a,  // pop rdx
+    0x59,  // pop rcx
+    0x58,  // pop rax
+    0x9d,  // popfq
+
+    0xc3,  // ret
+           // Read-only data goes here:
+           // uint64_t* afl_prev_loc_ptr
+           // uint8_t** afl_area_ptr_ptr
+           // unsigned int afl_instr_rms
+
+};
+
+#else
+
+static void on_basic_block(GumCpuContext *context, gpointer user_data) {
+
+  afl_maybe_log((guint64)user_data);
+
+}
+
+#endif
+
+void instr_basic_block(GumStalkerIterator *iterator, GumStalkerOutput *output,
+                       gpointer user_data) {
+
+  range_t *range = (range_t *)user_data;
+
+  const cs_insn *instr;
+  gboolean       begin = TRUE;
+  while (gum_stalker_iterator_next(iterator, &instr)) {
+
+    if (begin) {
+
+      if (instr->address >= range->code_start &&
+          instr->address <= range->code_end) {
+
+#if GUM_NATIVE_CPU == GUM_CPU_AMD64
+        GumX86Writer *cw = output->writer.x86;
+        if (range->current_log_impl == 0 ||
+            !gum_x86_writer_can_branch_directly_between(
+                cw->pc, range->current_log_impl) ||
+            !gum_x86_writer_can_branch_directly_between(
+                cw->pc + 128, range->current_log_impl)) {
+
+          gconstpointer after_log_impl = cw->code + 1;
+
+          gum_x86_writer_put_jmp_near_label(cw, after_log_impl);
+
+          range->current_log_impl = cw->pc;
+          gum_x86_writer_put_bytes(cw, afl_maybe_log_code,
+                                   sizeof(afl_maybe_log_code));
+
+          uint64_t *afl_prev_loc_ptr = &range->afl_prev_loc;
+          uint8_t **afl_area_ptr_ptr = &__afl_area_ptr;
+          gum_x86_writer_put_bytes(cw, (const guint8 *)&afl_prev_loc_ptr,
+                                   sizeof(afl_prev_loc_ptr));
+          gum_x86_writer_put_bytes(cw, (const guint8 *)&afl_area_ptr_ptr,
+                                   sizeof(afl_area_ptr_ptr));
+          gum_x86_writer_put_label(cw, after_log_impl);
+
+        }
+
+        gum_x86_writer_put_lea_reg_reg_offset(cw, GUM_REG_RSP, GUM_REG_RSP,
+                                              -GUM_RED_ZONE_SIZE);
+        gum_x86_writer_put_push_reg(cw, GUM_REG_RDI);
+        gum_x86_writer_put_mov_reg_address(cw, GUM_REG_RDI,
+                                           GUM_ADDRESS(instr->address));
+        gum_x86_writer_put_call_address(cw, range->current_log_impl);
+        gum_x86_writer_put_pop_reg(cw, GUM_REG_RDI);
+        gum_x86_writer_put_lea_reg_reg_offset(cw, GUM_REG_RSP, GUM_REG_RSP,
+                                              GUM_RED_ZONE_SIZE);
+#else
+        gum_stalker_iterator_put_callout(iterator, on_basic_block,
+                                         (gpointer)instr->address, NULL);
+#endif
+        begin = FALSE;
+
+      }
+
+    }
+
+    gum_stalker_iterator_keep(iterator);
+
+  }
+
+}
+
+/* Because this CAN be called more than once, it will return the LAST range */
+static int enumerate_ranges(const GumRangeDetails *details,
+                            gpointer               user_data) {
+
+  GumMemoryRange *code_range = (GumMemoryRange *)user_data;
+  memcpy(code_range, details->range, sizeof(*code_range));
+  return 0;
+
+}
+
+int main(int argc, char **argv) {
+
+#ifndef __APPLE__
+  (void)personality(ADDR_NO_RANDOMIZE);  // disable ASLR
+#endif
+
+  // STEP 2: load the library you want to fuzz and lookup the functions,
+  //         inclusive of the cleanup functions.
+  //         If there is just one function, then there is nothing to change
+  //         or add here.
+
+  void *dl = NULL;
+  if (argc > 2) {
+
+    dl = dlopen(argv[1], RTLD_LAZY);
+
+  } else {
+
+    dl = dlopen(TARGET_LIBRARY, RTLD_LAZY);
+
+  }
+
+  if (!dl) {
+
+    if (argc > 2)
+      fprintf(stderr, "Could not load %s\n", argv[1]);
+    else
+      fprintf(stderr, "Could not load %s\n", TARGET_LIBRARY);
+    exit(-1);
+
+  }
+
+  if (argc > 2)
+    o_function = dlsym(dl, argv[2]);
+  else
+    o_function = dlsym(dl, TARGET_FUNCTION);
+  if (!o_function) {
+
+    if (argc > 2)
+      fprintf(stderr, "Could not find function %s\n", argv[2]);
+    else
+      fprintf(stderr, "Could not find function %s\n", TARGET_FUNCTION);
+    exit(-1);
+
+  }
+
+  // END STEP 2
+
+  if (!getenv("AFL_FRIDA_TEST_INPUT")) {
+
+    gum_init_embedded();
+    if (!gum_stalker_is_supported()) {
+
+      gum_deinit_embedded();
+      return 1;
+
+    }
+
+    GumStalker *stalker = gum_stalker_new();
+
+    GumAddress base_address;
+    if (argc > 2)
+      base_address = gum_module_find_base_address(argv[1]);
+    else
+      base_address = gum_module_find_base_address(TARGET_LIBRARY);
+    GumMemoryRange code_range;
+    if (argc > 2)
+      gum_module_enumerate_ranges(argv[1], GUM_PAGE_RX, enumerate_ranges,
+                                  &code_range);
+    else
+      gum_module_enumerate_ranges(TARGET_LIBRARY, GUM_PAGE_RX, enumerate_ranges,
+                                  &code_range);
+
+    guint64 code_start = code_range.base_address;
+    guint64 code_end = code_range.base_address + code_range.size;
+    range_t instr_range = {0, code_start, code_end, 0, 0};
+
+    printf("Frida instrumentation: base=0x%lx instrumenting=0x%lx-%lx\n",
+           base_address, code_start, code_end);
+    if (!code_start || !code_end) {
+
+      if (argc > 2)
+        fprintf(stderr, "Error: no valid memory address found for %s\n",
+                argv[1]);
+      else
+        fprintf(stderr, "Error: no valid memory address found for %s\n",
+                TARGET_LIBRARY);
+      exit(-1);
+
+    }
+
+    GumStalkerTransformer *transformer =
+        gum_stalker_transformer_make_from_callback(instr_basic_block,
+                                                   &instr_range, NULL);
+
+    // to ensure that the signatures are not optimized out
+    memcpy(__afl_area_ptr, (void *)AFL_PERSISTENT, sizeof(AFL_PERSISTENT));
+    memcpy(__afl_area_ptr + 32, (void *)AFL_DEFER_FORKSVR,
+           sizeof(AFL_DEFER_FORKSVR));
+    __afl_manual_init();
+
+    //
+    // any expensive target library initialization that has to be done just once
+    // - put that here
+    //
+
+    gum_stalker_follow_me(stalker, transformer, NULL);
+
+    while (__afl_persistent_loop(UINT32_MAX) != 0) {
+
+      previous_pc = 0;  // Required!
+
+#ifdef _DEBUG
+      fprintf(stderr, "CLIENT crc: %016llx len: %u\n",
+              hash64(__afl_fuzz_ptr, *__afl_fuzz_len), *__afl_fuzz_len);
+      fprintf(stderr, "RECV:");
+      for (int i = 0; i < *__afl_fuzz_len; i++)
+        fprintf(stderr, "%02x", __afl_fuzz_ptr[i]);
+      fprintf(stderr, "\n");
+#endif
+
+      // STEP 3: ensure the minimum length is present and setup the target
+      //         function to fuzz.
+
+      if (*__afl_fuzz_len > 0) {
+
+        __afl_fuzz_ptr[*__afl_fuzz_len] = 0;  // if you need to null terminate
+        (*o_function)(__afl_fuzz_ptr, *__afl_fuzz_len);
+
+      }
+
+      // END STEP 3
+
+    }
+
+    gum_stalker_unfollow_me(stalker);
+
+    while (gum_stalker_garbage_collect(stalker))
+      g_usleep(10000);
+
+    g_object_unref(stalker);
+    g_object_unref(transformer);
+    gum_deinit_embedded();
+
+  } else {
+
+    char buf[8 * 1024] = {0};
+    int  count = read(0, buf, sizeof(buf));
+    buf[8 * 1024 - 1] = '\0';
+    (*o_function)(buf, count);
+
+  }
+
+  return 0;
+
+}
+
diff --git a/utils/afl_frida/afl-frida.h b/utils/afl_frida/afl-frida.h
new file mode 100644
index 00000000..efa3440f
--- /dev/null
+++ b/utils/afl_frida/afl-frida.h
@@ -0,0 +1,53 @@
+extern int is_persistent;
+
+G_BEGIN_DECLS
+
+#define GUM_TYPE_FAKE_EVENT_SINK (gum_fake_event_sink_get_type())
+
+G_DECLARE_FINAL_TYPE(GumFakeEventSink, gum_fake_event_sink, GUM,
+                     FAKE_EVENT_SINK, GObject)
+
+struct _GumFakeEventSink {
+
+  GObject      parent;
+  GumEventType mask;
+
+};
+
+GumEventSink *gum_fake_event_sink_new(void);
+void          gum_fake_event_sink_reset(GumFakeEventSink *self);
+
+G_END_DECLS
+
+typedef struct {
+
+  GumAddress base_address;
+  guint64    code_start, code_end;
+
+} range_t;
+
+void instr_basic_block(GumStalkerIterator *iterator, GumStalkerOutput *output,
+                       gpointer user_data);
+#pragma once
+
+void afl_setup(void);
+void afl_start_forkserver(void);
+int  __afl_persistent_loop(unsigned int max_cnt);
+
+inline static inline void afl_maybe_log(guint64 current_pc) {
+
+  extern unsigned int afl_instr_rms;
+  extern uint8_t *    afl_area_ptr;
+
+  static __thread guint64 previous_pc;
+
+  current_pc = (current_pc >> 4) ^ (current_pc << 8);
+  current_pc &= MAP_SIZE - 1;
+
+  if (current_pc >= afl_instr_rms) return;
+
+  afl_area_ptr[current_pc ^ previous_pc]++;
+  previous_pc = current_pc >> 1;
+
+}
+
diff --git a/utils/afl_frida/android/README.md b/utils/afl_frida/android/README.md
new file mode 100644
index 00000000..044b48a1
--- /dev/null
+++ b/utils/afl_frida/android/README.md
@@ -0,0 +1 @@
+For android, frida-gum package (ex. https://github.com/frida/frida/releases/download/14.2.6/frida-gum-devkit-14.2.6-android-arm64.tar.xz) is needed to be extracted in the directory.
diff --git a/utils/afl_frida/android/frida-gum-example.c b/utils/afl_frida/android/frida-gum-example.c
new file mode 100644
index 00000000..14d98248
--- /dev/null
+++ b/utils/afl_frida/android/frida-gum-example.c
@@ -0,0 +1,130 @@
+/*
+ * Compile with:
+ *
+ * clang -fPIC -DANDROID -ffunction-sections -fdata-sections -Os -pipe -g3 frida-gum-example.c -o frida-gum-example -L. -lfrida-gum -llog -ldl -lm -pthread -Wl,--gc-sections,-z,noexecstack,-z,relro,-z,now -fuse-ld=gold -fuse-ld=gold -Wl,--icf=all
+ *
+ * Visit https://frida.re to learn more about Frida.
+ */
+
+#include "frida-gum.h"
+
+#include <fcntl.h>
+#include <unistd.h>
+
+typedef struct _ExampleListener ExampleListener;
+typedef enum _ExampleHookId ExampleHookId;
+
+struct _ExampleListener
+{
+  GObject parent;
+
+  guint num_calls;
+};
+
+enum _ExampleHookId
+{
+  EXAMPLE_HOOK_OPEN,
+  EXAMPLE_HOOK_CLOSE
+};
+
+static void example_listener_iface_init (gpointer g_iface, gpointer iface_data);
+
+#define EXAMPLE_TYPE_LISTENER (example_listener_get_type ())
+G_DECLARE_FINAL_TYPE (ExampleListener, example_listener, EXAMPLE, LISTENER, GObject)
+G_DEFINE_TYPE_EXTENDED (ExampleListener,
+                        example_listener,
+                        G_TYPE_OBJECT,
+                        0,
+                        G_IMPLEMENT_INTERFACE (GUM_TYPE_INVOCATION_LISTENER,
+                            example_listener_iface_init))
+
+int
+main (int argc,
+      char * argv[])
+{
+  GumInterceptor * interceptor;
+  GumInvocationListener * listener;
+
+  gum_init_embedded ();
+
+  interceptor = gum_interceptor_obtain ();
+  listener = g_object_new (EXAMPLE_TYPE_LISTENER, NULL);
+
+  gum_interceptor_begin_transaction (interceptor);
+  gum_interceptor_attach (interceptor,
+      GSIZE_TO_POINTER (gum_module_find_export_by_name (NULL, "open")),
+      listener,
+      GSIZE_TO_POINTER (EXAMPLE_HOOK_OPEN));
+  gum_interceptor_attach (interceptor,
+      GSIZE_TO_POINTER (gum_module_find_export_by_name (NULL, "close")),
+      listener,
+      GSIZE_TO_POINTER (EXAMPLE_HOOK_CLOSE));
+  gum_interceptor_end_transaction (interceptor);
+
+  close (open ("/etc/hosts", O_RDONLY));
+  close (open ("/etc/fstab", O_RDONLY));
+
+  g_print ("[*] listener got %u calls\n", EXAMPLE_LISTENER (listener)->num_calls);
+
+  gum_interceptor_detach (interceptor, listener);
+
+  close (open ("/etc/hosts", O_RDONLY));
+  close (open ("/etc/fstab", O_RDONLY));
+
+  g_print ("[*] listener still has %u calls\n", EXAMPLE_LISTENER (listener)->num_calls);
+
+  g_object_unref (listener);
+  g_object_unref (interceptor);
+
+  gum_deinit_embedded ();
+
+  return 0;
+}
+
+static void
+example_listener_on_enter (GumInvocationListener * listener,
+                           GumInvocationContext * ic)
+{
+  ExampleListener * self = EXAMPLE_LISTENER (listener);
+  ExampleHookId hook_id = GUM_IC_GET_FUNC_DATA (ic, ExampleHookId);
+
+  switch (hook_id)
+  {
+    case EXAMPLE_HOOK_OPEN:
+      g_print ("[*] open(\"%s\")\n", (const gchar *) gum_invocation_context_get_nth_argument (ic, 0));
+      break;
+    case EXAMPLE_HOOK_CLOSE:
+      g_print ("[*] close(%d)\n", GPOINTER_TO_INT (gum_invocation_context_get_nth_argument (ic, 0)));
+      break;
+  }
+
+  self->num_calls++;
+}
+
+static void
+example_listener_on_leave (GumInvocationListener * listener,
+                           GumInvocationContext * ic)
+{
+}
+
+static void
+example_listener_class_init (ExampleListenerClass * klass)
+{
+  (void) EXAMPLE_IS_LISTENER;
+  (void) glib_autoptr_cleanup_ExampleListener;
+}
+
+static void
+example_listener_iface_init (gpointer g_iface,
+                             gpointer iface_data)
+{
+  GumInvocationListenerInterface * iface = g_iface;
+
+  iface->on_enter = example_listener_on_enter;
+  iface->on_leave = example_listener_on_leave;
+}
+
+static void
+example_listener_init (ExampleListener * self)
+{
+}
diff --git a/utils/afl_frida/libtestinstr.c b/utils/afl_frida/libtestinstr.c
new file mode 100644
index 00000000..96b1cf21
--- /dev/null
+++ b/utils/afl_frida/libtestinstr.c
@@ -0,0 +1,35 @@
+/*
+   american fuzzy lop++ - a trivial program to test the build
+   --------------------------------------------------------
+   Originally written by Michal Zalewski
+   Copyright 2014 Google Inc. All rights reserved.
+   Copyright 2019-2020 AFLplusplus Project. All rights reserved.
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at:
+     http://www.apache.org/licenses/LICENSE-2.0
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+
+void testinstr(char *buf, int len) {
+
+  if (len < 1) return;
+  buf[len] = 0;
+
+  // we support three input cases
+  if (buf[0] == '0')
+    printf("Looks like a zero to me!\n");
+  else if (buf[0] == '1')
+    printf("Pretty sure that is a one!\n");
+  else
+    printf("Neither one or zero? How quaint!\n");
+
+}
+