net: Add fuzzer for HostResolverImpl.

net/base/fuzzed_data_provider.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/base/fuzzed_data_provider.h"
 
 #include <algorithm>
 #include <limits>
 
 #include "base/logging.h"
 
 namespace net {
 
 FuzzedDataProvider::FuzzedDataProvider(const uint8_t* data, size_t size)
     : remaining_data_(reinterpret_cast<const char*>(data), size) {}
 
 FuzzedDataProvider::~FuzzedDataProvider() {}
 
 base::StringPiece FuzzedDataProvider::ConsumeBytes(size_t num_bytes) {
   num_bytes = std::min(num_bytes, remaining_data_.length());
   base::StringPiece result(remaining_data_.data(), num_bytes);
   remaining_data_ = remaining_data_.substr(num_bytes);
   return result;
 }
 
 base::StringPiece FuzzedDataProvider::ConsumeRemainingBytes() {
   return ConsumeBytes(remaining_data_.length());
 }
 
-uint32_t FuzzedDataProvider::ConsumeValueInRange(uint32_t min, uint32_t max) {
+uint32_t FuzzedDataProvider::ConsumeUint32InRange(uint32_t min, uint32_t max) {
   CHECK_LE(min, max);
 
   uint32_t range = max - min;
   uint32_t offset = 0;
   uint32_t result = 0;
 
   while ((range >> offset) > 0 && !remaining_data_.empty()) {
     // Pull bytes off the end of the seed data. Experimentally, this seems to
     // allow the fuzzer to more easily explore the input space. This makes
     // sense, since it works by modifying inputs that caused new code to run,
     // and this data is often used to encode length of data read by
     // ConsumeBytes. Separating out read lengths makes it easier modify the
     // contents of the data that is actually read.
     uint8_t next_byte = remaining_data_.back();
     remaining_data_.remove_suffix(1);
     result = (result << 8) | next_byte;
     offset += 8;
   }
 
   // Avoid division by 0, in the case |range + 1| results in overflow.
   if (range == std::numeric_limits<uint32_t>::max())
     return result;
 
   return min + result % (range + 1);
 }
 
+int FuzzedDataProvider::ConsumeInt32InRange(int min, int max) {
+  CHECK_LE(min, max);
+
+  uint32_t range = max - min;
+  return min + ConsumeUint32InRange(0, range);
+}
+
 bool FuzzedDataProvider::ConsumeBool() {
   return (ConsumeUint8() & 0x01) == 0x01;
 }
 
 uint8_t FuzzedDataProvider::ConsumeUint8() {
-  return ConsumeValueInRange(0, 0xFF);
+  return ConsumeUint32InRange(0, 0xFF);
 }
 
 uint16_t FuzzedDataProvider::ConsumeUint16() {
-  return ConsumeValueInRange(0, 0xFFFF);
+  return ConsumeUint32InRange(0, 0xFFFF);
 }
 
 }  // namespace net