// Copyright 2025 Google LLC

//

// 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

//

// Unless required by applicable law or agreed to in writing, software

// distributed under the License is distributed on an "AS IS" BASIS,

// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

// See the License for the specific language governing permissions and

// limitations under the License.

//

////////////////////////////////////////////////////////////////////////////////

#include <cstring>

#include <stddef.h>

#include <stdint.h>

#include <string.h>

#include <stdlib.h>

#include <algorithm>

#include <vector>

#include <fuzzer/FuzzedDataProvider.h>

extern "C" {

  #include "mhd_str.h"

  #include "microhttpd2.h"

}

static void fuzz_tokens(FuzzedDataProvider& fdp) {

  // Prepare random string for string comparison

  std::string payload1 = fdp.ConsumeRandomLengthString(1024);

  std::string payload2 = fdp.ConsumeRandomLengthString(1024);

  std::string payload3 = fdp.ConsumeRandomLengthString(1024);

  const char *payload_str1 = payload1.c_str();

  const char *payload_str2 = payload2.c_str();

  const char *payload_str3 = payload3.c_str();

  size_t payload_size1 = payload1.size();

  size_t payload_size2 = payload2.size();

  size_t payload_size3 = payload3.size();

  // Fuzz mhd_str_equal_caseless

  mhd_str_equal_caseless(payload_str1, payload_str2);

  // Fuzz mhd_str_equal_caseless_n

  mhd_str_equal_caseless_n(payload_str1, payload_str2, fdp.ConsumeIntegral<size_t>());

  // Fuzz mhd_str_equal_caseless_bin_n

  const size_t min_len = std::min(payload_size1, payload_size2);

  if (min_len) {

    mhd_str_equal_caseless_bin_n(payload_str1, payload_str2, min_len);

  }

  // Fuzz mhd_str_has_token_caseless

  mhd_str_has_token_caseless(payload_str1, payload_str2, payload_size1);

  mhd_str_has_token_caseless(payload_str1, payload_str2, payload_size2);

  // Fuzz mhd_str_remove_token_caseless

  ssize_t out_sz = (ssize_t)fdp.ConsumeIntegralInRange<int>(1, 1024);

  char *out_buf = (char*) malloc((size_t)out_sz);

  mhd_str_remove_token_caseless(payload_str1, payload_size1, payload_str2, payload_size2,

                                out_buf, &out_sz);

  free(out_buf);

  // Fuzz mhd_str_starts_with_token_opt_param

  struct MHD_String mhd_str1 {

    payload_size1, payload_str1

  };

  struct MHD_String mhd_str2 {

    payload_size2, payload_str2

  };

  mhd_str_starts_with_token_opt_param(&mhd_str1, &mhd_str2);

  // Fuzz mhd_str_starts_with_token_req_param

  bool needs_uni = fdp.ConsumeBool();

  struct MHD_String mhd_str3 {

    payload_size3, payload_str3

  };

  struct mhd_BufferConst str3_buf { 0, nullptr };

  mhd_str_starts_with_token_req_param(&mhd_str1, &mhd_str2, &mhd_str3, &str3_buf, &needs_uni);

}

static void fuzz_conversion(FuzzedDataProvider& fdp) {

  // Prepare random string for string/int conversion

  std::string payload = fdp.ConsumeRandomLengthString(1024);

  const char *payload_str = payload.c_str();

  size_t payload_size = payload.size();

  uint_fast32_t u32 = 0;

  uint_fast64_t u64 = 0;

  char small[4], big[128];

  size_t max_len = fdp.ConsumeIntegralInRange<size_t>(0, payload_size);

  // Fuzz conversion between string and uint64 with random payload

  mhd_str_to_uint64(payload_str, &u64);

  mhd_str_to_uint64_n(payload_str, max_len, &u64);

  mhd_strx_to_uint64(payload_str, &u64);

  mhd_strx_to_uint64_n(payload_str, max_len, &u64);

  mhd_uint64_to_str((uint_fast64_t)fdp.ConsumeIntegral<uint64_t>(), small, sizeof(small));

  mhd_uint64_to_str((uint_fast64_t)fdp.ConsumeIntegral<uint64_t>(), big, sizeof(big));

  // Fuzz string to uint32 conversion with random payload string

  mhd_strx_to_uint32(payload_str, &u32);

  mhd_strx_to_uint32_n(payload_str, max_len, &u32);

  // Fuzz uint16 to string conversion with random payload

  mhd_uint16_to_str((uint_least16_t)fdp.ConsumeIntegralInRange<unsigned>(0, 65535), small, sizeof(small));

  mhd_uint16_to_str((uint_least16_t)fdp.ConsumeIntegralInRange<unsigned>(0, 65535), big, sizeof(big));

}

static void fuzz_decode(FuzzedDataProvider& fdp) {

  // Prepare random data for string decode

  bool ignored = false;

  std::string payload = fdp.ConsumeRandomLengthString(1024);

  char *payload_str = payload.data();

  size_t payload_size = payload.size();

  // Fuzz decode functions with random payload

  char *out1 = (char*) malloc(payload_size);

  char *out2 = (char*) malloc(payload_size);

  if (out1) {

    mhd_str_pct_decode_strict_n(payload_str, payload_size, out1, payload_size);

  }

  if (out2) {

    mhd_str_pct_decode_lenient_n(payload_str, payload_size, out2, payload_size, &ignored);

  }

  // Fuzz decode in place functions with random payload

  mhd_str_pct_decode_in_place_strict(payload_str);

  mhd_str_pct_decode_in_place_lenient(payload_str, &ignored);

  free(out1);

  free(out2);

}

static void fuzz_quoted(FuzzedDataProvider& fdp) {

  // Prepare random data for quote and equality check

  std::string payload1 = fdp.ConsumeRandomLengthString(1024);

  std::string payload2 = fdp.ConsumeRandomLengthString(1024);

  const char *payload_str1 = payload1.c_str();

  const char *payload_str2 = payload2.c_str();

  size_t payload_size1 = payload1.size();

  size_t payload_size2 = payload2.size();

  // Fuzz mhd_str_equal_quoted_bin_n with random string payload as binary

  mhd_str_equal_quoted_bin_n(payload_str1, payload_size1, payload_str2, payload_size2);

  // Fuzz mhd_str_quote and mhd_str_unquote with random string payload

  size_t max_out = payload_size1 * 2;

  char *out = (char*) malloc(max_out);

  if (out) {

    mhd_str_quote(payload_str1, payload_size1, out, max_out);

    mhd_str_unquote(payload_str1, payload_size1, out);

  }

  free(out);

  max_out = payload_size2 * 2;

  out = (char*) malloc(max_out);

  if (out) {

    mhd_str_quote(payload_str2, payload_size2, out, max_out);

    mhd_str_unquote(payload_str2, payload_size2, out);

  }

  free(out);

}

static void fuzz_base64(FuzzedDataProvider& fdp) {

  // Prepare random data for base64 conversion

  std::string payload = fdp.ConsumeRandomLengthString(1024);

  char *payload_str = payload.data();

  size_t payload_size = payload.size();

  // Prepare a valid base64 string from random payload

  static const char valid_chars[] =

    "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

  for (size_t i = 0; i < payload_size; i++) {

    payload_str[i] = valid_chars[((uint8_t)i) % 64];

  }

  // Fuzz mhd_base64_to_bin_n with the random base64 string

  size_t max_out = (payload.size() / 4) * 4;

  uint8_t* out = (uint8_t*) malloc(payload_size);

  if (out) {

    mhd_base64_to_bin_n(payload_str, payload_size, out, max_out);

    free(out);

  }

}

static void fuzz_transformation(FuzzedDataProvider& fdp) {

  // Fuzz targets in multiple rounds

  for (int i = 0; i < fdp.ConsumeIntegralInRange<unsigned>(1, 8); i++) {

    // Generate random integer

    int value = fdp.ConsumeIntegral<int>();

    // Fuzz conversion functions

    MHD_http_method_to_string(static_cast<MHD_HTTP_Method>(value));

    MHD_predef_header_to_string(static_cast<MHD_PredefinedHeader>(value));

    MHD_protocol_version_to_string(static_cast<MHD_HTTP_ProtocolVersion>(value));

  }

}

static void fuzz_hex_conversion(FuzzedDataProvider& fdp) {

  // Prepare random data for hex conversion

  std::string payload = fdp.ConsumeRandomLengthString(1024);

  char *payload_str = payload.data();

  size_t payload_size = payload.size();

  // Fuzz mhd_hex_to_bin with random payload

  uint8_t *bin_out = (uint8_t*) malloc(payload_size);

  if (bin_out) {

    mhd_hex_to_bin(payload_str, payload_size, bin_out);

    free(bin_out);

  }

  // Fuzz mhd_bin_to_hex with random payload

  char *hex_out = (char *) malloc(payload_size * 2);

  if (hex_out) {

    if (!payload.empty()) {

      mhd_bin_to_hex(payload_str, payload_size, hex_out);

    }

    free(hex_out);

  }

  char *hexz_out = (char *) malloc(payload_size * 2 + 1);

  if (hexz_out) {

    if (!payload.empty()) {

      mhd_bin_to_hex(payload_str, payload_size, hexz_out);

    }

    free(hexz_out);

  }

}

extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {

  FuzzedDataProvider fdp(data, size);

  for (int i = 0; i < fdp.ConsumeIntegralInRange<unsigned>(1, 6); i++) {

    switch (fdp.ConsumeIntegralInRange<int>(0, 7)) {

      case 0: fuzz_tokens(fdp); break;

      case 1: fuzz_conversion(fdp); break;

      case 2: fuzz_decode(fdp); break;

      case 3: fuzz_quoted(fdp); break;

      case 4: fuzz_base64(fdp); break;

      case 5: fuzz_transformation(fdp); break;

      case 6: fuzz_hex_conversion(fdp); break;

    }

  }

  return 0;

}