text: // Copyright (c) 2020 The Widecoin Core developers
  // Distributed under the MIT software license, see the accompanying
  // file COPYING or http://www.opensource.org/licenses/mit-license.php.
  
  #include <httpserver.h>
  #include <netaddress.h>
  #include <test/fuzz/FuzzedDataProvider.h>
  #include <test/fuzz/fuzz.h>
  #include <test/fuzz/util.h>
  #include <util/strencodings.h>
  
  #include <event2/buffer.h>
  #include <event2/event.h>
  #include <event2/http.h>
  #include <event2/http_struct.h>
  
  #include <cassert>
  #include <cstdint>
  #include <string>
  #include <vector>
  
  // workaround for libevent versions before 2.1.1,
  // when internal functions didn't have underscores at the end
  #if LIBEVENT_VERSION_NUMBER < 0x02010100
  extern "C" int evhttp_parse_firstline(struct evhttp_request*, struct evbuffer*);
  extern "C" int evhttp_parse_headers(struct evhttp_request*, struct evbuffer*);
  inline int evhttp_parse_firstline_(struct evhttp_request* r, struct evbuffer* b)
  {
      return evhttp_parse_firstline(r, b);
  }
  inline int evhttp_parse_headers_(struct evhttp_request* r, struct evbuffer* b)
  {
      return evhttp_parse_headers(r, b);
  }
  #else
  extern "C" int evhttp_parse_firstline_(struct evhttp_request*, struct evbuffer*);
  extern "C" int evhttp_parse_headers_(struct evhttp_request*, struct evbuffer*);
  #endif
  
  std::string RequestMethodString(HTTPRequest::RequestMethod m);
  
  FUZZ_TARGET(http_request)
  {
      FuzzedDataProvider fuzzed_data_provider{buffer.data(), buffer.size()};
      evhttp_request* evreq = evhttp_request_new(nullptr, nullptr);
      assert(evreq != nullptr);
      evreq->kind = EVHTTP_REQUEST;
      evbuffer* evbuf = evbuffer_new();
      assert(evbuf != nullptr);
      const std::vector<uint8_t> http_buffer = ConsumeRandomLengthByteVector(fuzzed_data_provider, 4096);
      evbuffer_add(evbuf, http_buffer.data(), http_buffer.size());
      // Avoid constructing requests that will be interpreted by libevent as PROXY requests to avoid triggering
      // a nullptr dereference. The dereference (req->evcon->http_server) takes place in evhttp_parse_request_line
      // and is a consequence of our hacky but necessary use of the internal function evhttp_parse_firstline_ in
      // this fuzzing harness. The workaround is not aesthetically pleasing, but it successfully avoids the troublesome
      // code path. " http:// HTTP/1.1\n" was a crashing input prior to this workaround.
      const std::string http_buffer_str = ToLower({http_buffer.begin(), http_buffer.end()});
      if (http_buffer_str.find(" http://") != std::string::npos || http_buffer_str.find(" https://") != std::string::npos ||
          evhttp_parse_firstline_(evreq, evbuf) != 1 || evhttp_parse_headers_(evreq, evbuf) != 1) {
          evbuffer_free(evbuf);
          evhttp_request_free(evreq);
          return;
      }
  
      HTTPRequest http_request{evreq, true};
      const HTTPRequest::RequestMethod request_method = http_request.GetRequestMethod();
      (void)RequestMethodString(request_method);
      (void)http_request.GetURI();
      (void)http_request.GetHeader("Host");
      const std::string header = fuzzed_data_provider.ConsumeRandomLengthString(16);
      (void)http_request.GetHeader(header);
      (void)http_request.WriteHeader(header, fuzzed_data_provider.ConsumeRandomLengthString(16));
      (void)http_request.GetHeader(header);
      const std::string body = http_request.ReadBody();
      assert(body.empty());
      const CService service = http_request.GetPeer();
      assert(service.ToString() == "[::]:0");
  
      evbuffer_free(evbuf);
      evhttp_request_free(evreq);
  }
  