fix: JSON parsing of negative STNumber and STAmount (#5990)

This change fixes JSON parsing of negative `int` input in `STNumber` and `STAmount`. The conversion of JSON to `STNumber` or `STAmount` may trigger a condition where we negate smallest possible `int` value, which is undefined behaviour. We use a temporary storage as `int64_t` to avoid this bug. Note that this only affects RPC, because we do not parse JSON in the protocol layer, and hence no amendment is needed.

include/xrpl/json/json_value.h

@@ -5,6 +5,7 @@
 #include <xrpl/json/json_forwards.h>
 
 #include <cstring>
+#include <limits>
 #include <map>
 #include <string>
 #include <vector>
@@ -139,9 +140,9 @@ public:
     using ArrayIndex = UInt;
 
     static Value const null;
-    static Int const minInt;
+    static constexpr Int minInt = std::numeric_limits<Int>::min();
-    static Int const maxInt;
+    static constexpr Int maxInt = std::numeric_limits<Int>::max();
-    static UInt const maxUInt;
+    static constexpr UInt maxUInt = std::numeric_limits<UInt>::max();
 
 private:
     class CZString
@@ -244,6 +245,10 @@ public:
     bool
     asBool() const;
 
+    /** Correct absolute value from int or unsigned int */
+    UInt
+    asAbsUInt() const;
+
     // TODO: What is the "empty()" method this docstring mentions?
     /** isNull() tests to see if this field is null.  Don't use this method to
         test for emptiness: use empty(). */

src/libxrpl/json/json_value.cpp

@@ -14,9 +14,6 @@
 namespace Json {
 
 Value const Value::null;
-Int const Value::minInt = Int(~(UInt(-1) / 2));
-Int const Value::maxInt = Int(UInt(-1) / 2);
-UInt const Value::maxUInt = UInt(-1);
 
 class DefaultValueAllocator : public ValueAllocator
 {
@@ -550,6 +547,69 @@ Value::asInt() const
     return 0;  // unreachable;
 }
 
+UInt
+Value::asAbsUInt() const
+{
+    switch (type_)
+    {
+        case nullValue:
+            return 0;
+
+        case intValue: {
+            // Doing this conversion through int64 avoids overflow error for
+            // value_.int_ = -1 * 2^31 i.e. numeric_limits<int>::min().
+            if (value_.int_ < 0)
+                return static_cast<std::int64_t>(value_.int_) * -1;
+            return value_.int_;
+        }
+
+        case uintValue:
+            return value_.uint_;
+
+        case realValue: {
+            if (value_.real_ < 0)
+            {
+                JSON_ASSERT_MESSAGE(
+                    -1 * value_.real_ <= maxUInt,
+                    "Real out of unsigned integer range");
+                return UInt(-1 * value_.real_);
+            }
+            JSON_ASSERT_MESSAGE(
+                value_.real_ <= maxUInt, "Real out of unsigned integer range");
+            return UInt(value_.real_);
+        }
+
+        case booleanValue:
+            return value_.bool_ ? 1 : 0;
+
+        case stringValue: {
+            char const* const str{value_.string_ ? value_.string_ : ""};
+            auto const temp = beast::lexicalCastThrow<std::int64_t>(str);
+            if (temp < 0)
+            {
+                JSON_ASSERT_MESSAGE(
+                    -1 * temp <= maxUInt,
+                    "String out of unsigned integer range");
+                return -1 * temp;
+            }
+            JSON_ASSERT_MESSAGE(
+                temp <= maxUInt, "String out of unsigned integer range");
+            return temp;
+        }
+
+        case arrayValue:
+        case objectValue:
+            JSON_ASSERT_MESSAGE(false, "Type is not convertible to int");
+
+            // LCOV_EXCL_START
+        default:
+            UNREACHABLE("Json::Value::asAbsInt : invalid type");
+            // LCOV_EXCL_STOP
+    }
+
+    return 0;  // unreachable;
+}
+
 Value::UInt
 Value::asUInt() const
 {

src/libxrpl/protocol/STAmount.cpp

@@ -1087,7 +1087,7 @@ amountFromJson(SField const& name, Json::Value const& v)
         }
         else
         {
-            parts.mantissa = -value.asInt();
+            parts.mantissa = value.asAbsUInt();
             parts.negative = true;
         }
     }

src/libxrpl/protocol/STNumber.cpp

@@ -169,7 +169,7 @@ numberFromJson(SField const& field, Json::Value const& value)
         }
         else
         {
-            parts.mantissa = -value.asInt();
+            parts.mantissa = value.asAbsUInt();
             parts.negative = true;
         }
     }

src/test/app/ValidatorSite_test.cpp

@@ -572,7 +572,7 @@ public:
                   false,
                   true,
                   1,
-                  std::chrono::seconds{Json::Value::maxInt + 1}}});
+                  std::chrono::seconds{Json::Value::minInt}}});
             // force an out-of-range validUntil value on the future list
             // The first list is accepted. The second fails. The parser
             // returns the "best" result, so this looks like a success.
@@ -608,7 +608,7 @@ public:
                   false,
                   true,
                   1,
-                  std::chrono::seconds{Json::Value::maxInt + 1},
+                  std::chrono::seconds{Json::Value::minInt},
                   std::chrono::seconds{Json::Value::maxInt - 6000}}});
             // verify refresh intervals are properly clamped
             testFetchList(

src/test/protocol/STAmount_test.cpp

@@ -3,6 +3,7 @@
 #include <xrpl/basics/random.h>
 #include <xrpl/beast/unit_test.h>
 #include <xrpl/protocol/STAmount.h>
+#include <xrpl/protocol/XRPAmount.h>
 
 namespace ripple {
 
@@ -585,6 +586,216 @@ public:
 #endif
     }
 
+    void
+    testParseJson()
+    {
+        static_assert(!std::is_convertible_v<STAmount*, Number*>);
+
+        {
+            STAmount const stnum{sfNumber};
+            BEAST_EXPECT(stnum.getSType() == STI_AMOUNT);
+            BEAST_EXPECT(stnum.getText() == "0");
+            BEAST_EXPECT(stnum.isDefault() == true);
+            BEAST_EXPECT(stnum.value() == Number{0});
+        }
+
+        {
+            BEAST_EXPECT(
+                amountFromJson(sfNumber, Json::Value(42)) == XRPAmount(42));
+            BEAST_EXPECT(
+                amountFromJson(sfNumber, Json::Value(-42)) == XRPAmount(-42));
+
+            BEAST_EXPECT(
+                amountFromJson(sfNumber, Json::UInt(42)) == XRPAmount(42));
+
+            BEAST_EXPECT(amountFromJson(sfNumber, "-123") == XRPAmount(-123));
+
+            BEAST_EXPECT(amountFromJson(sfNumber, "123") == XRPAmount(123));
+            BEAST_EXPECT(amountFromJson(sfNumber, "-123") == XRPAmount(-123));
+
+            BEAST_EXPECT(amountFromJson(sfNumber, "3.14e2") == XRPAmount(314));
+            BEAST_EXPECT(
+                amountFromJson(sfNumber, "-3.14e2") == XRPAmount(-314));
+
+            BEAST_EXPECT(amountFromJson(sfNumber, "0") == XRPAmount(0));
+            BEAST_EXPECT(amountFromJson(sfNumber, "-0") == XRPAmount(0));
+
+            constexpr auto imin = std::numeric_limits<int>::min();
+            BEAST_EXPECT(amountFromJson(sfNumber, imin) == XRPAmount(imin));
+            BEAST_EXPECT(
+                amountFromJson(sfNumber, std::to_string(imin)) ==
+                XRPAmount(imin));
+
+            constexpr auto imax = std::numeric_limits<int>::max();
+            BEAST_EXPECT(amountFromJson(sfNumber, imax) == XRPAmount(imax));
+            BEAST_EXPECT(
+                amountFromJson(sfNumber, std::to_string(imax)) ==
+                XRPAmount(imax));
+
+            constexpr auto umax = std::numeric_limits<unsigned int>::max();
+            BEAST_EXPECT(amountFromJson(sfNumber, umax) == XRPAmount(umax));
+            BEAST_EXPECT(
+                amountFromJson(sfNumber, std::to_string(umax)) ==
+                XRPAmount(umax));
+
+            // XRP does not handle fractional part
+            try
+            {
+                auto _ = amountFromJson(sfNumber, "0.0");
+                BEAST_EXPECT(false);
+            }
+            catch (std::runtime_error const& e)
+            {
+                std::string const expected =
+                    "XRP and MPT must be specified as integral amount.";
+                BEAST_EXPECT(e.what() == expected);
+            }
+
+            // XRP does not handle fractional part
+            try
+            {
+                auto _ = amountFromJson(sfNumber, "1000e-2");
+                BEAST_EXPECT(false);
+            }
+            catch (std::runtime_error const& e)
+            {
+                std::string const expected =
+                    "XRP and MPT must be specified as integral amount.";
+                BEAST_EXPECT(e.what() == expected);
+            }
+
+            // Obvious non-numbers tested here
+            try
+            {
+                auto _ = amountFromJson(sfNumber, "");
+                BEAST_EXPECT(false);
+            }
+            catch (std::runtime_error const& e)
+            {
+                std::string const expected = "'' is not a number";
+                BEAST_EXPECT(e.what() == expected);
+            }
+
+            try
+            {
+                auto _ = amountFromJson(sfNumber, "e");
+                BEAST_EXPECT(false);
+            }
+            catch (std::runtime_error const& e)
+            {
+                std::string const expected = "'e' is not a number";
+                BEAST_EXPECT(e.what() == expected);
+            }
+
+            try
+            {
+                auto _ = amountFromJson(sfNumber, "1e");
+                BEAST_EXPECT(false);
+            }
+            catch (std::runtime_error const& e)
+            {
+                std::string const expected = "'1e' is not a number";
+                BEAST_EXPECT(e.what() == expected);
+            }
+
+            try
+            {
+                auto _ = amountFromJson(sfNumber, "e2");
+                BEAST_EXPECT(false);
+            }
+            catch (std::runtime_error const& e)
+            {
+                std::string const expected = "'e2' is not a number";
+                BEAST_EXPECT(e.what() == expected);
+            }
+
+            try
+            {
+                auto _ = amountFromJson(sfNumber, Json::Value());
+                BEAST_EXPECT(false);
+            }
+            catch (std::runtime_error const& e)
+            {
+                std::string const expected =
+                    "XRP may not be specified with a null Json value";
+                BEAST_EXPECT(e.what() == expected);
+            }
+
+            try
+            {
+                auto _ = amountFromJson(
+                    sfNumber,
+                    "123456789012345678901234567890123456789012345678901234"
+                    "5678"
+                    "901234567890123456789012345678901234567890123456789012"
+                    "3456"
+                    "78901234567890123456789012345678901234567890");
+                BEAST_EXPECT(false);
+            }
+            catch (std::bad_cast const& e)
+            {
+                BEAST_EXPECT(true);
+            }
+
+            // We do not handle leading zeros
+            try
+            {
+                auto _ = amountFromJson(sfNumber, "001");
+                BEAST_EXPECT(false);
+            }
+            catch (std::runtime_error const& e)
+            {
+                std::string const expected = "'001' is not a number";
+                BEAST_EXPECT(e.what() == expected);
+            }
+
+            try
+            {
+                auto _ = amountFromJson(sfNumber, "000.0");
+                BEAST_EXPECT(false);
+            }
+            catch (std::runtime_error const& e)
+            {
+                std::string const expected = "'000.0' is not a number";
+                BEAST_EXPECT(e.what() == expected);
+            }
+
+            // We do not handle dangling dot
+            try
+            {
+                auto _ = amountFromJson(sfNumber, ".1");
+                BEAST_EXPECT(false);
+            }
+            catch (std::runtime_error const& e)
+            {
+                std::string const expected = "'.1' is not a number";
+                BEAST_EXPECT(e.what() == expected);
+            }
+
+            try
+            {
+                auto _ = amountFromJson(sfNumber, "1.");
+                BEAST_EXPECT(false);
+            }
+            catch (std::runtime_error const& e)
+            {
+                std::string const expected = "'1.' is not a number";
+                BEAST_EXPECT(e.what() == expected);
+            }
+
+            try
+            {
+                auto _ = amountFromJson(sfNumber, "1.e3");
+                BEAST_EXPECT(false);
+            }
+            catch (std::runtime_error const& e)
+            {
+                std::string const expected = "'1.e3' is not a number";
+                BEAST_EXPECT(e.what() == expected);
+            }
+        }
+    }
+
     void
     testConvertXRP()
     {
@@ -1022,6 +1233,7 @@ public:
         testArithmetic();
         testUnderflow();
         testRounding();
+        testParseJson();
         testConvertXRP();
         testConvertIOU();
         testCanAddXRP();

src/test/protocol/STNumber_test.cpp

@@ -2,6 +2,7 @@
 #include <xrpl/beast/unit_test/suite.h>
 #include <xrpl/json/json_forwards.h>
 #include <xrpl/protocol/Issue.h>
+#include <xrpl/protocol/SField.h>
 #include <xrpl/protocol/STAmount.h>
 #include <xrpl/protocol/STNumber.h>
 
@@ -126,6 +127,30 @@ struct STNumber_test : public beast::unit_test::suite
             BEAST_EXPECT(
                 numberFromJson(sfNumber, "-0.000e6") == STNumber(sfNumber, 0));
 
+            constexpr auto imin = std::numeric_limits<int>::min();
+            BEAST_EXPECT(
+                numberFromJson(sfNumber, imin) ==
+                STNumber(sfNumber, Number(imin, 0)));
+            BEAST_EXPECT(
+                numberFromJson(sfNumber, std::to_string(imin)) ==
+                STNumber(sfNumber, Number(imin, 0)));
+
+            constexpr auto imax = std::numeric_limits<int>::max();
+            BEAST_EXPECT(
+                numberFromJson(sfNumber, imax) ==
+                STNumber(sfNumber, Number(imax, 0)));
+            BEAST_EXPECT(
+                numberFromJson(sfNumber, std::to_string(imax)) ==
+                STNumber(sfNumber, Number(imax, 0)));
+
+            constexpr auto umax = std::numeric_limits<unsigned int>::max();
+            BEAST_EXPECT(
+                numberFromJson(sfNumber, umax) ==
+                STNumber(sfNumber, Number(umax, 0)));
+            BEAST_EXPECT(
+                numberFromJson(sfNumber, std::to_string(umax)) ==
+                STNumber(sfNumber, Number(umax, 0)));
+
             // Obvious non-numbers tested here
             try
             {

src/tests/libxrpl/json/Value.cpp

@@ -7,6 +7,7 @@
 #include <doctest/doctest.h>
 
 #include <algorithm>
+#include <cmath>
 #include <regex>
 #include <sstream>
 #include <string>
@@ -15,6 +16,14 @@ namespace ripple {
 
 TEST_SUITE_BEGIN("json_value");
 
+TEST_CASE("limits")
+{
+    using namespace Json;
+    static_assert(Value::minInt == Int(~(UInt(-1) / 2)));
+    static_assert(Value::maxInt == Int(UInt(-1) / 2));
+    static_assert(Value::maxUInt == UInt(-1));
+}
+
 TEST_CASE("construct and compare Json::StaticString")
 {
     static constexpr char sample[]{"Contents of a Json::StaticString"};
@@ -582,8 +591,6 @@ TEST_CASE("bad json")
 
 TEST_CASE("edge cases")
 {
-    std::string json;
-
     std::uint32_t max_uint = std::numeric_limits<std::uint32_t>::max();
     std::int32_t max_int = std::numeric_limits<std::int32_t>::max();
     std::int32_t min_int = std::numeric_limits<std::int32_t>::min();
@@ -592,71 +599,145 @@ TEST_CASE("edge cases")
     std::int32_t a_large_int = max_int - 1978;
     std::int32_t a_small_int = min_int + 1978;
 
-    json = "{\"max_uint\":" + std::to_string(max_uint);
+    {
-    json += ",\"max_int\":" + std::to_string(max_int);
+        std::string json = "{\"max_uint\":" + std::to_string(max_uint);
-    json += ",\"min_int\":" + std::to_string(min_int);
+        json += ",\"max_int\":" + std::to_string(max_int);
-    json += ",\"a_uint\":" + std::to_string(a_uint);
+        json += ",\"min_int\":" + std::to_string(min_int);
-    json += ",\"a_large_int\":" + std::to_string(a_large_int);
+        json += ",\"a_uint\":" + std::to_string(a_uint);
-    json += ",\"a_small_int\":" + std::to_string(a_small_int);
+        json += ",\"a_large_int\":" + std::to_string(a_large_int);
-    json += "}";
+        json += ",\"a_small_int\":" + std::to_string(a_small_int);
+        json += "}";
 
-    Json::Value j1;
+        Json::Value j1;
-    Json::Reader r1;
+        Json::Reader r1;
 
-    CHECK(r1.parse(json, j1));
+        CHECK(r1.parse(json, j1));
-    CHECK(j1["max_uint"].asUInt() == max_uint);
+        CHECK(j1["max_uint"].asUInt() == max_uint);
-    CHECK(j1["max_int"].asInt() == max_int);
+        CHECK(j1["max_uint"].asAbsUInt() == max_uint);
-    CHECK(j1["min_int"].asInt() == min_int);
+        CHECK(j1["max_int"].asInt() == max_int);
-    CHECK(j1["a_uint"].asUInt() == a_uint);
+        CHECK(j1["max_int"].asAbsUInt() == max_int);
-    CHECK(j1["a_uint"] > a_large_int);
+        CHECK(j1["min_int"].asInt() == min_int);
-    CHECK(j1["a_uint"] > a_small_int);
+        CHECK(
-    CHECK(j1["a_large_int"].asInt() == a_large_int);
+            j1["min_int"].asAbsUInt() ==
-    CHECK(j1["a_large_int"].asUInt() == a_large_int);
+            static_cast<std::int64_t>(min_int) * -1);
-    CHECK(j1["a_large_int"] < a_uint);
+        CHECK(j1["a_uint"].asUInt() == a_uint);
-    CHECK(j1["a_small_int"].asInt() == a_small_int);
+        CHECK(j1["a_uint"].asAbsUInt() == a_uint);
-    CHECK(j1["a_small_int"] < a_uint);
+        CHECK(j1["a_uint"] > a_large_int);
+        CHECK(j1["a_uint"] > a_small_int);
+        CHECK(j1["a_large_int"].asInt() == a_large_int);
+        CHECK(j1["a_large_int"].asAbsUInt() == a_large_int);
+        CHECK(j1["a_large_int"].asUInt() == a_large_int);
+        CHECK(j1["a_large_int"] < a_uint);
+        CHECK(j1["a_small_int"].asInt() == a_small_int);
+        CHECK(
+            j1["a_small_int"].asAbsUInt() ==
+            static_cast<std::int64_t>(a_small_int) * -1);
+        CHECK(j1["a_small_int"] < a_uint);
+    }
 
-    json = "{\"overflow\":";
+    std::uint64_t overflow = std::uint64_t(max_uint) + 1;
-    json += std::to_string(std::uint64_t(max_uint) + 1);
+    {
-    json += "}";
+        std::string json = "{\"overflow\":";
+        json += std::to_string(overflow);
+        json += "}";
 
-    Json::Value j2;
+        Json::Value j2;
-    Json::Reader r2;
+        Json::Reader r2;
 
-    CHECK(!r2.parse(json, j2));
+        CHECK(!r2.parse(json, j2));
+    }
 
-    json = "{\"underflow\":";
+    std::int64_t underflow = std::int64_t(min_int) - 1;
-    json += std::to_string(std::int64_t(min_int) - 1);
+    {
-    json += "}";
+        std::string json = "{\"underflow\":";
+        json += std::to_string(underflow);
+        json += "}";
 
-    Json::Value j3;
+        Json::Value j3;
-    Json::Reader r3;
+        Json::Reader r3;
 
-    CHECK(!r3.parse(json, j3));
+        CHECK(!r3.parse(json, j3));
+    }
 
-    Json::Value intString{"4294967296"};
+    {
-    CHECK_THROWS_AS(intString.asUInt(), beast::BadLexicalCast);
+        Json::Value intString{std::to_string(overflow)};
+        CHECK_THROWS_AS(intString.asUInt(), beast::BadLexicalCast);
+        CHECK_THROWS_AS(intString.asAbsUInt(), Json::error);
 
-    intString = "4294967295";
+        intString = "4294967295";
-    CHECK(intString.asUInt() == 4294967295u);
+        CHECK(intString.asUInt() == 4294967295u);
+        CHECK(intString.asAbsUInt() == 4294967295u);
 
-    intString = "0";
+        intString = "0";
-    CHECK(intString.asUInt() == 0);
+        CHECK(intString.asUInt() == 0);
+        CHECK(intString.asAbsUInt() == 0);
 
-    intString = "-1";
+        intString = "-1";
-    CHECK_THROWS_AS(intString.asUInt(), beast::BadLexicalCast);
+        CHECK_THROWS_AS(intString.asUInt(), beast::BadLexicalCast);
+        CHECK(intString.asAbsUInt() == 1);
 
-    intString = "2147483648";
+        intString = "-4294967295";
-    CHECK_THROWS_AS(intString.asInt(), beast::BadLexicalCast);
+        CHECK(intString.asAbsUInt() == 4294967295);
 
-    intString = "2147483647";
+        intString = "-4294967296";
-    CHECK(intString.asInt() == 2147483647);
+        CHECK_THROWS_AS(intString.asAbsUInt(), Json::error);
 
-    intString = "-2147483648";
+        intString = "2147483648";
-    CHECK(intString.asInt() == -2147483648LL);  // MSVC wants the LL
+        CHECK_THROWS_AS(intString.asInt(), beast::BadLexicalCast);
+        CHECK(intString.asAbsUInt() == 2147483648);
 
-    intString = "-2147483649";
+        intString = "2147483647";
-    CHECK_THROWS_AS(intString.asInt(), beast::BadLexicalCast);
+        CHECK(intString.asInt() == 2147483647);
+        CHECK(intString.asAbsUInt() == 2147483647);
+
+        intString = "-2147483648";
+        CHECK(intString.asInt() == -2147483648LL);  // MSVC wants the LL
+        CHECK(intString.asAbsUInt() == 2147483648LL);
+
+        intString = "-2147483649";
+        CHECK_THROWS_AS(intString.asInt(), beast::BadLexicalCast);
+        CHECK(intString.asAbsUInt() == 2147483649);
+    }
+
+    {
+        Json::Value intReal{4294967297.0};
+        CHECK_THROWS_AS(intReal.asUInt(), Json::error);
+        CHECK_THROWS_AS(intReal.asAbsUInt(), Json::error);
+
+        intReal = 4294967295.0;
+        CHECK(intReal.asUInt() == 4294967295u);
+        CHECK(intReal.asAbsUInt() == 4294967295u);
+
+        intReal = 0.0;
+        CHECK(intReal.asUInt() == 0);
+        CHECK(intReal.asAbsUInt() == 0);
+
+        intReal = -1.0;
+        CHECK_THROWS_AS(intReal.asUInt(), Json::error);
+        CHECK(intReal.asAbsUInt() == 1);
+
+        intReal = -4294967295.0;
+        CHECK(intReal.asAbsUInt() == 4294967295);
+
+        intReal = -4294967296.0;
+        CHECK_THROWS_AS(intReal.asAbsUInt(), Json::error);
+
+        intReal = 2147483648.0;
+        CHECK_THROWS_AS(intReal.asInt(), Json::error);
+        CHECK(intReal.asAbsUInt() == 2147483648);
+
+        intReal = 2147483647.0;
+        CHECK(intReal.asInt() == 2147483647);
+        CHECK(intReal.asAbsUInt() == 2147483647);
+
+        intReal = -2147483648.0;
+        CHECK(intReal.asInt() == -2147483648LL);  // MSVC wants the LL
+        CHECK(intReal.asAbsUInt() == 2147483648LL);
+
+        intReal = -2147483649.0;
+        CHECK_THROWS_AS(intReal.asInt(), Json::error);
+        CHECK(intReal.asAbsUInt() == 2147483649);
+    }
 }
 
 TEST_CASE("copy")
@@ -793,6 +874,7 @@ TEST_CASE("conversions")
         CHECK(val.asString() == "");
         CHECK(val.asInt() == 0);
         CHECK(val.asUInt() == 0);
+        CHECK(val.asAbsUInt() == 0);
         CHECK(val.asDouble() == 0.0);
         CHECK(val.asBool() == false);
 
@@ -813,6 +895,7 @@ TEST_CASE("conversions")
         CHECK(val.asString() == "-1234");
         CHECK(val.asInt() == -1234);
         CHECK_THROWS_AS(val.asUInt(), Json::error);
+        CHECK(val.asAbsUInt() == 1234u);
         CHECK(val.asDouble() == -1234.0);
         CHECK(val.asBool() == true);
 
@@ -833,6 +916,7 @@ TEST_CASE("conversions")
         CHECK(val.asString() == "1234");
         CHECK(val.asInt() == 1234);
         CHECK(val.asUInt() == 1234u);
+        CHECK(val.asAbsUInt() == 1234u);
         CHECK(val.asDouble() == 1234.0);
         CHECK(val.asBool() == true);
 
@@ -853,6 +937,7 @@ TEST_CASE("conversions")
         CHECK(std::regex_match(val.asString(), std::regex("^2\\.0*$")));
         CHECK(val.asInt() == 2);
         CHECK(val.asUInt() == 2u);
+        CHECK(val.asAbsUInt() == 2u);
         CHECK(val.asDouble() == 2.0);
         CHECK(val.asBool() == true);
 
@@ -873,6 +958,7 @@ TEST_CASE("conversions")
         CHECK(val.asString() == "54321");
         CHECK(val.asInt() == 54321);
         CHECK(val.asUInt() == 54321u);
+        CHECK(val.asAbsUInt() == 54321);
         CHECK_THROWS_AS(val.asDouble(), Json::error);
         CHECK(val.asBool() == true);
 
@@ -893,6 +979,7 @@ TEST_CASE("conversions")
         CHECK(val.asString() == "");
         CHECK_THROWS_AS(val.asInt(), std::exception);
         CHECK_THROWS_AS(val.asUInt(), std::exception);
+        CHECK_THROWS_AS(val.asAbsUInt(), std::exception);
         CHECK_THROWS_AS(val.asDouble(), std::exception);
         CHECK(val.asBool() == false);
 
@@ -913,6 +1000,7 @@ TEST_CASE("conversions")
         CHECK(val.asString() == "false");
         CHECK(val.asInt() == 0);
         CHECK(val.asUInt() == 0);
+        CHECK(val.asAbsUInt() == 0);
         CHECK(val.asDouble() == 0.0);
         CHECK(val.asBool() == false);
 
@@ -933,6 +1021,7 @@ TEST_CASE("conversions")
         CHECK(val.asString() == "true");
         CHECK(val.asInt() == 1);
         CHECK(val.asUInt() == 1);
+        CHECK(val.asAbsUInt() == 1);
         CHECK(val.asDouble() == 1.0);
         CHECK(val.asBool() == true);
 
@@ -953,6 +1042,7 @@ TEST_CASE("conversions")
         CHECK_THROWS_AS(val.asString(), Json::error);
         CHECK_THROWS_AS(val.asInt(), Json::error);
         CHECK_THROWS_AS(val.asUInt(), Json::error);
+        CHECK_THROWS_AS(val.asAbsUInt(), Json::error);
         CHECK_THROWS_AS(val.asDouble(), Json::error);
         CHECK(val.asBool() == false);  // empty or not
 
@@ -973,6 +1063,7 @@ TEST_CASE("conversions")
         CHECK_THROWS_AS(val.asString(), Json::error);
         CHECK_THROWS_AS(val.asInt(), Json::error);
         CHECK_THROWS_AS(val.asUInt(), Json::error);
+        CHECK_THROWS_AS(val.asAbsUInt(), Json::error);
         CHECK_THROWS_AS(val.asDouble(), Json::error);
         CHECK(val.asBool() == false);  // empty or not