Coverage Report

Created: 2025-08-26 06:29

/src/fuzz_response.cpp
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Source (jump to first uncovered line)
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// Copyright 2025 Google LLC
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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//      http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//
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////////////////////////////////////////////////////////////////////////////////
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#include <stdint.h>
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#include <stddef.h>
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#include <unistd.h>
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#include <sys/types.h>
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#include <vector>
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#include <algorithm>
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#include "mhd_helper.h"
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static void request_ended_cb(void *cls,
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                             const struct MHD_RequestEndedData *data,
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0
                             void *request_app_context) {
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  // Do nothing
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0
}
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1.43k
static enum MHD_HTTP_StatusCode pick_status_code(FuzzedDataProvider &fdp) {
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  // Randomly pick a valid or invalid HTTP response status code
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1.43k
  return fdp.ConsumeBool()
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1.43k
      ? fdp.PickValueInArray({
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1.06k
          MHD_HTTP_STATUS_OK, MHD_HTTP_STATUS_CREATED, MHD_HTTP_STATUS_NO_CONTENT,
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1.06k
          MHD_HTTP_STATUS_PARTIAL_CONTENT, MHD_HTTP_STATUS_BAD_REQUEST,
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1.06k
          MHD_HTTP_STATUS_UNAUTHORIZED, MHD_HTTP_STATUS_FORBIDDEN,
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          MHD_HTTP_STATUS_NOT_FOUND, MHD_HTTP_STATUS_INTERNAL_SERVER_ERROR })
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1.43k
      : (enum MHD_HTTP_StatusCode)(fdp.ConsumeIntegralInRange<int>(0, 999));
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1.43k
}
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static MHD_Response* create_response(FuzzedDataProvider &fdp,
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1.43k
                                     enum MHD_HTTP_StatusCode sc) {
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1.43k
  struct MHD_Response* r = nullptr;
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  // Generate random response body
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1.43k
  const size_t body_len = fdp.ConsumeIntegralInRange<size_t>(
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1.43k
      0, std::min<size_t>(fdp.remaining_bytes(), 8192));
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1.43k
  std::string body = fdp.ConsumeBytesAsString(body_len);
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  // Randomly select which constructing function to use for respone object creation
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1.43k
  enum CtorKind {
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1.43k
    EMPTY, BUF_STATIC, BUF_COPY, IOVEC, FROM_FD, FROM_PIPE
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1.43k
  };
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1.43k
  CtorKind ctor = fdp.PickValueInArray<CtorKind>(
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1.43k
      {EMPTY, BUF_STATIC, BUF_COPY, IOVEC, FROM_FD, FROM_PIPE});
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1.43k
  switch (ctor) {
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0
    default:
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536
    case EMPTY: {
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      // Create empty response
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536
      r = MHD_response_from_empty(sc);
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      break;
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0
    }
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218
    case BUF_STATIC: {
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      // Create response with random body and static buffer status
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      r = MHD_response_from_buffer_static(sc, body.size(), body.c_str());
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      break;
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0
    }
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    case BUF_COPY: {
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      // Create response with random body and copy buffer in
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      r = MHD_response_from_buffer_copy(sc, body.size(), body.data());
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      break;
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0
    }
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220
    case IOVEC: {
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      // Create response from random IO vector
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      unsigned cnt = fdp.ConsumeIntegralInRange<unsigned>(0, 6);
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      std::vector<MHD_IoVec> iov(cnt);
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      std::vector<std::string> chunks; chunks.reserve(cnt);
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      for (unsigned i=0;i<cnt;i++) {
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        chunks.push_back(fdp.ConsumeBytesAsString(
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                           fdp.ConsumeIntegralInRange<size_t>(0, 1024)));
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        iov[i].iov_base = chunks.back().data();
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        iov[i].iov_len  = chunks.back().size();
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      }
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      r = MHD_response_from_iovec(sc, cnt ? cnt : 0, cnt ? iov.data() : nullptr, nullptr, nullptr);
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      break;
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    }
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    case FROM_FD: {
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      // Create response from file with random data
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      char path[] = "/tmp/mhdrespXXXXXX";
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      int fd = mkstemp(path);
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      if (fd >= 0) {
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        unlink(path);
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        if (!body.empty()) (void) ::write(fd, body.data(), body.size());
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        uint64_t sz = (uint64_t)body.size();
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        uint64_t off = 0;
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        if (fdp.ConsumeBool()) {
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          off = std::min<uint64_t>(sz, fdp.ConsumeIntegral<uint64_t>() % (sz + 1));
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        }
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        uint64_t len = (sz > off) ? (fdp.ConsumeIntegral<uint64_t>() % (sz - off + 1)) : 0;
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        r = MHD_response_from_fd(sc, fd, off, len);
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        if (!r) {
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          close(fd);
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        }
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      }
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      break;
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    }
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    case FROM_PIPE: {
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      // Create response by piping in random data
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      int pfd[2];
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      if (0 == pipe(pfd)) {
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        std::string pbytes = fdp.ConsumeBytesAsString(
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                               fdp.ConsumeIntegralInRange<size_t>(0, 2048));
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        if (!pbytes.empty()) {
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          ::write(pfd[1], pbytes.data(), pbytes.size());
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        }
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        close(pfd[1]);
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        r = MHD_response_from_pipe(sc, pfd[0]);
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        if (!r) {
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          close(pfd[0]);
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        }
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      }
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      break;
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0
    }
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1.43k
  }
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1.43k
  return r;
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1.43k
}
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1.35k
static void add_headers(FuzzedDataProvider &fdp, MHD_Response *r) {
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1.35k
  const char* ct = fdp.ConsumeBool() ? "text/plain" : "application/octet-stream";
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1.35k
  MHD_response_add_header(r, "Content-Type", ct);
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  // Add random standard headers
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1.35k
  size_t num_headers = fdp.ConsumeIntegralInRange<size_t>(0, 10);
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3.82k
  for (size_t i = 0; i < num_headers; i++) {
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2.47k
    std::string name = safe_ascii(fdp.ConsumeRandomLengthString(20), false);
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2.47k
    std::string val  = safe_ascii(fdp.ConsumeRandomLengthString(60), true);
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    MHD_response_add_header(r, name.c_str(), val.c_str());
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  }
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  // Add random predefined header
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1.35k
  enum MHD_PredefinedHeader which =
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1.35k
    fdp.PickValueInArray<enum MHD_PredefinedHeader>(
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1.35k
      { MHD_PREDEF_ACCEPT_CHARSET, MHD_PREDEF_ACCEPT_LANGUAGE });
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1.35k
  std::string value = safe_ascii(fdp.ConsumeRandomLengthString(32));
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1.35k
  MHD_response_add_predef_header(r, which, value.c_str());
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1.35k
}
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1.35k
static void randomise_response_options(FuzzedDataProvider &fdp, MHD_Response *r) {
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1.35k
  if (fdp.ConsumeBool()) {
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    auto o = MHD_R_OPTION_REUSABLE(ToMhdBool(fdp.ConsumeBool()));
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    MHD_response_set_option(r, &o);
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  }
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1.35k
  if (fdp.ConsumeBool()) {
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    auto o = MHD_R_OPTION_HEAD_ONLY_RESPONSE(ToMhdBool(fdp.ConsumeBool()));
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    MHD_response_set_option(r, &o);
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  }
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1.35k
  if (fdp.ConsumeBool()) {
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    auto o = MHD_R_OPTION_CHUNKED_ENC(ToMhdBool(fdp.ConsumeBool()));
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    MHD_response_set_option(r, &o);
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  }
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1.35k
  if (fdp.ConsumeBool()) {
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    auto o = MHD_R_OPTION_CONN_CLOSE(ToMhdBool(fdp.ConsumeBool()));
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    MHD_response_set_option(r, &o);
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  }
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1.35k
  if (fdp.ConsumeBool()) {
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    auto o = MHD_R_OPTION_HTTP_1_0_SERVER(ToMhdBool(fdp.ConsumeBool()));
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    MHD_response_set_option(r, &o);
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  }
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1.35k
  if (fdp.ConsumeBool()) {
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    auto o = MHD_R_OPTION_HTTP_1_0_COMPATIBLE_STRICT(ToMhdBool(fdp.ConsumeBool()));
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    MHD_response_set_option(r, &o);
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  }
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1.35k
  if (fdp.ConsumeBool()) {
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    auto o = MHD_R_OPTION_INSANITY_HEADER_CONTENT_LENGTH(ToMhdBool(fdp.ConsumeBool()));
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    MHD_response_set_option(r, &o);
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  }
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1.35k
  if (fdp.ConsumeBool()) {
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    auto o = MHD_R_OPTION_TERMINATION_CALLBACK(&request_ended_cb, nullptr);
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    MHD_response_set_option(r, &o);
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  }
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1.35k
}
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static void add_auth(FuzzedDataProvider &fdp, MHD_Response *r,
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1.35k
                     enum MHD_HTTP_StatusCode sc) {
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1.35k
  if (sc == MHD_HTTP_STATUS_UNAUTHORIZED) {
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    // Randomly add different challenge under 401 status code
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    if (fdp.ConsumeBool()) {
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      // Use digest challenge
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      std::string realm = safe_ascii(fdp.ConsumeRandomLengthString(24));
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      MHD_response_add_auth_basic_challenge(r, realm.c_str(), ToMhdBool(fdp.ConsumeBool()));
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      if (fdp.ConsumeBool()) {
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        std::string drealm = safe_ascii(fdp.ConsumeRandomLengthString(24));
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        const char* opaque = fdp.ConsumeBool() ? "opaque" : nullptr;
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        const char* domain = fdp.ConsumeBool() ? "/a /b"  : nullptr;
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        enum MHD_DigestAuthMultiQOP mqop =
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          fdp.ConsumeBool()? MHD_DIGEST_AUTH_MULT_QOP_AUTH : MHD_DIGEST_AUTH_MULT_QOP_AUTH_INT;
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        enum MHD_DigestAuthMultiAlgo malgo =
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          fdp.ConsumeBool()? MHD_DIGEST_AUTH_MULT_ALGO_ANY : MHD_DIGEST_AUTH_MULT_ALGO_MD5;
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        MHD_response_add_auth_digest_challenge(
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            r, drealm.c_str(), opaque, domain, ToMhdBool(fdp.ConsumeBool()),
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            mqop, malgo, ToMhdBool(fdp.ConsumeBool()), ToMhdBool(fdp.ConsumeBool()));
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      }
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    } else {
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      // Use basic challenge
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      std::string realm = safe_ascii(fdp.ConsumeRandomLengthString(24));
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      const char* opaque = fdp.ConsumeBool() ? "opaque" : nullptr;
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      const char* domain = fdp.ConsumeBool() ? "/a /b"  : nullptr;
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      enum MHD_DigestAuthMultiQOP mqop =
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        fdp.ConsumeBool()? MHD_DIGEST_AUTH_MULT_QOP_AUTH : MHD_DIGEST_AUTH_MULT_QOP_AUTH_INT;
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      enum MHD_DigestAuthMultiAlgo malgo =
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        fdp.ConsumeBool()? MHD_DIGEST_AUTH_MULT_ALGO_ANY : MHD_DIGEST_AUTH_MULT_ALGO_MD5;
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      MHD_response_add_auth_digest_challenge(
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          r, realm.c_str(), opaque, domain, ToMhdBool(fdp.ConsumeBool()),
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          mqop, malgo, ToMhdBool(fdp.ConsumeBool()),
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          ToMhdBool(fdp.ConsumeBool()));
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      if (fdp.ConsumeBool()) {
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36
        std::string brealm = safe_ascii(fdp.ConsumeRandomLengthString(24));
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36
        MHD_response_add_auth_basic_challenge(r, brealm.c_str(), ToMhdBool(fdp.ConsumeBool()));
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36
      }
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212
    }
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985
  } else {
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    // For all other status code, randomly determine if challenges are added
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    // Randomly choose if basic challenge is used or not
230
985
    if (fdp.ConsumeBool()) {
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226
      std::string realm = safe_ascii(fdp.ConsumeRandomLengthString(24));
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      MHD_response_add_auth_basic_challenge(r, realm.c_str(), ToMhdBool(fdp.ConsumeBool()));
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226
    }
234
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    // Randomly choose if disgest challenge is used or not
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985
    if (fdp.ConsumeBool()) {
237
232
      std::string realm = safe_ascii(fdp.ConsumeRandomLengthString(24));
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232
      const char* opaque = fdp.ConsumeBool() ? "opaque" : nullptr;
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      const char* domain = fdp.ConsumeBool() ? "/a /b"  : nullptr;
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232
      enum MHD_DigestAuthMultiQOP mqop =
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232
        fdp.ConsumeBool()? MHD_DIGEST_AUTH_MULT_QOP_AUTH : MHD_DIGEST_AUTH_MULT_QOP_AUTH_INT;
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232
      enum MHD_DigestAuthMultiAlgo malgo =
243
232
        fdp.ConsumeBool()? MHD_DIGEST_AUTH_MULT_ALGO_ANY : MHD_DIGEST_AUTH_MULT_ALGO_MD5;
244
232
      MHD_response_add_auth_digest_challenge(
245
232
          r, realm.c_str(), opaque, domain, ToMhdBool(fdp.ConsumeBool()),
246
232
          mqop, malgo, ToMhdBool(fdp.ConsumeBool()), ToMhdBool(fdp.ConsumeBool()));
247
232
    }
248
985
  }
249
1.35k
}
250
251
1.43k
extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
252
1.43k
  if (size == 0) {
253
0
    return 0;
254
0
  }
255
1.43k
  FuzzedDataProvider fdp(data, size);
256
257
  // Pick a random response status code
258
1.43k
  enum MHD_HTTP_StatusCode sc = pick_status_code(fdp);
259
260
  // Create a random response object
261
1.43k
  struct MHD_Response* r = create_response(fdp, sc);
262
1.43k
  if (!r) {
263
85
    return 0;
264
85
  }
265
266
  // Add random headers into the response object
267
1.35k
  add_headers(fdp, r);
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269
  // Set random options for the response object
270
1.35k
  randomise_response_options(fdp, r);
271
272
  // Add authentication challenges to response
273
1.35k
  add_auth(fdp, r, sc);
274
275
  // Fuzz additional targets on response status
276
1.35k
  MHD_HTTP_status_code_to_string(sc);
277
1.35k
  MHD_status_code_to_string((enum MHD_StatusCode)sc);
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279
  // Destory the response object
280
1.35k
  MHD_response_destroy(r);
281
1.35k
  return 0;
282
1.43k
}