tests: Add fuzzing harness for serialization/deserialization of floating-points and integrals

Summary:
```
Add simple fuzzing harness for functions with floating-point parameters
(such as ser_double_to_uint64(double), etc.).

Add serialization/deserialization fuzzing for integral types.
```

Backport of core [[bitcoin/bitcoin#17996 | PR17996]].

The first and last commit are not relevant to us.

Test Plan:
  ninja bitcoin-fuzzers
  ./test/fuzz/test_runner.py <path_to_corpus>

Reviewers: #bitcoin_abc, deadalnix

Reviewed By: #bitcoin_abc, deadalnix

Differential Revision: https://reviews.bitcoinabc.org/D8249

Author: practicalswift

src/test/fuzz/CMakeLists.txt

@@ -84,6 +84,7 @@ add_regular_fuzz_targets(
 	cashaddr
 	descriptor_parse
 	eval_script
+	float
 	hex
 	integer
 	net_permissions

src/test/fuzz/float.cpp

@@ -0,0 +1,42 @@
+// Copyright (c) 2020 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <memusage.h>
+#include <serialize.h>
+#include <streams.h>
+#include <version.h>
+
+#include <test/fuzz/FuzzedDataProvider.h>
+#include <test/fuzz/fuzz.h>
+
+#include <cassert>
+#include <cstdint>
+
+void test_one_input(const std::vector<uint8_t> &buffer) {
+    FuzzedDataProvider fuzzed_data_provider(buffer.data(), buffer.size());
+
+    {
+        const double d = fuzzed_data_provider.ConsumeFloatingPoint<double>();
+        (void)memusage::DynamicUsage(d);
+        assert(ser_uint64_to_double(ser_double_to_uint64(d)) == d);
+
+        CDataStream stream(SER_NETWORK, INIT_PROTO_VERSION);
+        stream << d;
+        double d_deserialized;
+        stream >> d_deserialized;
+        assert(d == d_deserialized);
+    }
+
+    {
+        const float f = fuzzed_data_provider.ConsumeFloatingPoint<float>();
+        (void)memusage::DynamicUsage(f);
+        assert(ser_uint32_to_float(ser_float_to_uint32(f)) == f);
+
+        CDataStream stream(SER_NETWORK, INIT_PROTO_VERSION);
+        stream << f;
+        float f_deserialized;
+        stream >> f_deserialized;
+        assert(f == f_deserialized);
+    }
+}

src/test/fuzz/integer.cpp

@@ -21,10 +21,12 @@
 #include <script/signingprovider.h>
 #include <script/standard.h>
 #include <serialize.h>
+#include <streams.h>
 #include <uint256.h>
 #include <util/strencodings.h>
 #include <util/system.h>
 #include <util/time.h>
+#include <version.h>
 
 #include <test/fuzz/FuzzedDataProvider.h>
 #include <test/fuzz/fuzz.h>
@@ -57,6 +59,7 @@ void test_one_input(const std::vector<uint8_t> &buffer) {
     // We cannot assume a specific value of std::is_signed<char>::value:
     // ConsumeIntegral<char>() instead of casting from {u,}int8_t.
     const char ch = fuzzed_data_provider.ConsumeIntegral<char>();
+    const bool b = fuzzed_data_provider.ConsumeBool();
 
     const Consensus::Params &consensus_params = Params().GetConsensus();
     (void)CheckProofOfWork(BlockHash(u256), u32, consensus_params);
@@ -131,4 +134,68 @@ void test_one_input(const std::vector<uint8_t> &buffer) {
         (void)GetScriptForDestination(destination);
         (void)IsValidDestination(destination);
     }
+
+    {
+        CDataStream stream(SER_NETWORK, INIT_PROTO_VERSION);
+
+        uint256 deserialized_u256;
+        stream << u256;
+        stream >> deserialized_u256;
+        assert(u256 == deserialized_u256 && stream.empty());
+
+        uint160 deserialized_u160;
+        stream << u160;
+        stream >> deserialized_u160;
+        assert(u160 == deserialized_u160 && stream.empty());
+
+        uint64_t deserialized_u64;
+        stream << u64;
+        stream >> deserialized_u64;
+        assert(u64 == deserialized_u64 && stream.empty());
+
+        int64_t deserialized_i64;
+        stream << i64;
+        stream >> deserialized_i64;
+        assert(i64 == deserialized_i64 && stream.empty());
+
+        uint32_t deserialized_u32;
+        stream << u32;
+        stream >> deserialized_u32;
+        assert(u32 == deserialized_u32 && stream.empty());
+
+        int32_t deserialized_i32;
+        stream << i32;
+        stream >> deserialized_i32;
+        assert(i32 == deserialized_i32 && stream.empty());
+
+        uint16_t deserialized_u16;
+        stream << u16;
+        stream >> deserialized_u16;
+        assert(u16 == deserialized_u16 && stream.empty());
+
+        int16_t deserialized_i16;
+        stream << i16;
+        stream >> deserialized_i16;
+        assert(i16 == deserialized_i16 && stream.empty());
+
+        uint8_t deserialized_u8;
+        stream << u8;
+        stream >> deserialized_u8;
+        assert(u8 == deserialized_u8 && stream.empty());
+
+        int8_t deserialized_i8;
+        stream << i8;
+        stream >> deserialized_i8;
+        assert(i8 == deserialized_i8 && stream.empty());
+
+        char deserialized_ch;
+        stream << ch;
+        stream >> deserialized_ch;
+        assert(ch == deserialized_ch && stream.empty());
+
+        bool deserialized_b;
+        stream << b;
+        stream >> deserialized_b;
+        assert(b == deserialized_b && stream.empty());
+    }
 }