Add cpp-httplib to oss-fuzz (#684)

* *Add server fuzzer target  and seed corpus
* Add fuzz_test option to Makefile

* Fix #685

* Try to fix Github actions on Ubuntu

* Added ReadTimeoutSSL test

* Comment out `-fsanitize=address`

* Rebase upstream changes

* remove address sanitizer temporarily

* Add separate Makefile for fuzzing

* 1. Remove special char from dictionary
2. Clean fuzzing/Makefile

* Use specific path to avoid accidently linking openssl version brought in by oss-fuzz

* remove addition of flags

* Refactor Makefile

* Add missing newline

* Add fuzztest to github workflow

* Fix

Co-authored-by: yhirose <yuji.hirose.bug@gmail.com>

test/fuzzing/standalone_fuzz_target_runner.cpp

@@ -0,0 +1,35 @@
+// Copyright 2017 Google Inc. All Rights Reserved.
+// Licensed under the Apache License, Version 2.0 (the "License");
+
+// This runner does not do any fuzzing, but allows us to run the fuzz target
+// on the test corpus or on a single file,
+// e.g. the one that comes from a bug report.
+
+#include <cassert>
+#include <iostream>
+#include <fstream>
+#include <vector>
+
+// Forward declare the "fuzz target" interface.
+// We deliberately keep this inteface simple and header-free.
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size);
+
+// It reads all files passed as parameters and feeds their contents
+// one by one into the fuzz target (LLVMFuzzerTestOneInput).
+int main(int argc, char **argv) {
+  for (int i = 1; i < argc; i++) {
+    std::ifstream in(argv[i]);
+    in.seekg(0, in.end);
+    size_t length = in.tellg();
+    in.seekg (0, in.beg);
+    std::cout << "Reading " << length << " bytes from " << argv[i] << std::endl;
+    // Allocate exactly length bytes so that we reliably catch buffer overflows.
+    std::vector<char> bytes(length);
+    in.read(bytes.data(), bytes.size());
+    LLVMFuzzerTestOneInput(reinterpret_cast<const uint8_t *>(bytes.data()),
+                           bytes.size());
+    std::cout << "Execution successful" << std::endl;
+  }
+  std::cout << "Execution finished" << std::endl;
+  return 0;
+}