Handle number overflow during parsing of min/max values

Author: Robulane

src/Microsoft.OpenApi.Readers/ParseNodes/ParserHelper.cs

@@ -0,0 +1,35 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT license.
+
+using System;
+using System.Globalization;
+
+namespace Microsoft.OpenApi.Readers.ParseNodes
+{
+    /// <summary>
+    /// Useful tools to parse data
+    /// </summary>
+    internal class ParserHelper
+    {
+        /// <summary>
+        /// Parses decimal in invariant culture.
+        /// If the decimal is too big or small, it returns the default value
+        /// 
+        /// Note: sometimes developers put Double.MaxValue or Long.MaxValue as min/max values for numbers in json schema even if their numbers are not expected to be that big/small.
+        /// As we have already released the library with Decimal type for Max/Min, let's not introduce the breaking change and just fallback to Decimal.Max / Min. This should satisfy almost every scenario.
+        /// We can revisit this if somebody really needs to have double or long here.
+        /// </summary>
+        /// <returns></returns>
+        public static decimal ParseDecimalWithFallbackOnOverflow(string value, decimal defaultValue)
+        {
+            try
+            {
+                return decimal.Parse(value, NumberStyles.Float, CultureInfo.InvariantCulture);
+            }
+            catch (OverflowException)
+            {
+                return defaultValue;
+            }
+        }
+    }
+}

src/Microsoft.OpenApi.Readers/V2/OpenApiHeaderDeserializer.cs

@@ -1,4 +1,4 @@
-// Copyright (c) Microsoft Corporation. All rights reserved.
+// Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT license.
 
 using System;
@@ -44,15 +44,15 @@ internal static partial class OpenApiV2Deserializer
             },
             {
                 "maximum",
-                (o, n) => GetOrCreateSchema(o).Maximum = decimal.Parse(n.GetScalarValue(), CultureInfo.InvariantCulture)
+                (o, n) => GetOrCreateSchema(o).Maximum = ParserHelper.ParseDecimalWithFallbackOnOverflow(n.GetScalarValue(), decimal.MaxValue)
             },
             {
                 "exclusiveMaximum",
                 (o, n) => GetOrCreateSchema(o).ExclusiveMaximum = bool.Parse(n.GetScalarValue())
             },
             {
                 "minimum",
-                (o, n) => GetOrCreateSchema(o).Minimum = decimal.Parse(n.GetScalarValue(), CultureInfo.InvariantCulture)
+                (o, n) => GetOrCreateSchema(o).Minimum = ParserHelper.ParseDecimalWithFallbackOnOverflow(n.GetScalarValue(), decimal.MinValue)
             },
             {
                 "exclusiveMinimum",

src/Microsoft.OpenApi.Readers/V2/OpenApiParameterDeserializer.cs

@@ -61,11 +61,11 @@ internal static partial class OpenApiV2Deserializer
                 },
                 {
                     "minimum",
-                    (o, n) => GetOrCreateSchema(o).Minimum = decimal.Parse(n.GetScalarValue(), CultureInfo.InvariantCulture)
+                    (o, n) => GetOrCreateSchema(o).Minimum = ParserHelper.ParseDecimalWithFallbackOnOverflow(n.GetScalarValue(), decimal.MinValue)
                 },
                 {
                     "maximum",
-                    (o, n) => GetOrCreateSchema(o).Maximum = decimal.Parse(n.GetScalarValue(), CultureInfo.InvariantCulture)
+                    (o, n) => GetOrCreateSchema(o).Maximum = ParserHelper.ParseDecimalWithFallbackOnOverflow(n.GetScalarValue(), decimal.MaxValue)
                 },
                 {
                     "maxLength",

src/Microsoft.OpenApi.Readers/V2/OpenApiSchemaDeserializer.cs

@@ -27,15 +27,15 @@ internal static partial class OpenApiV2Deserializer
             },
             {
                 "maximum",
-                (o, n) => o.Maximum = decimal.Parse(n.GetScalarValue(), NumberStyles.Float, CultureInfo.InvariantCulture)
+                (o, n) => o.Maximum = ParserHelper.ParseDecimalWithFallbackOnOverflow(n.GetScalarValue(), decimal.MaxValue)
             },
             {
                 "exclusiveMaximum",
                 (o, n) => o.ExclusiveMaximum = bool.Parse(n.GetScalarValue())
             },
             {
                 "minimum",
-                (o, n) => o.Minimum = decimal.Parse(n.GetScalarValue(), NumberStyles.Float, CultureInfo.InvariantCulture)
+                (o, n) => o.Minimum = ParserHelper.ParseDecimalWithFallbackOnOverflow(n.GetScalarValue(), decimal.MinValue)
             },
             {
                 "exclusiveMinimum",

src/Microsoft.OpenApi.Readers/V3/OpenApiSchemaDeserializer.cs

@@ -27,15 +27,15 @@ internal static partial class OpenApiV3Deserializer
             },
             {
                 "maximum",
-                (o, n) => o.Maximum = decimal.Parse(n.GetScalarValue(), NumberStyles.Float, CultureInfo.InvariantCulture)
+                (o, n) => o.Maximum = ParserHelper.ParseDecimalWithFallbackOnOverflow(n.GetScalarValue(), decimal.MaxValue)
             },
             {
                 "exclusiveMaximum",
                 (o, n) => o.ExclusiveMaximum = bool.Parse(n.GetScalarValue())
             },
             {
                 "minimum",
-                (o, n) => o.Minimum = decimal.Parse(n.GetScalarValue(), NumberStyles.Float, CultureInfo.InvariantCulture)
+                (o, n) => o.Minimum = ParserHelper.ParseDecimalWithFallbackOnOverflow(n.GetScalarValue(), decimal.MinValue)
             },
             {
                 "exclusiveMinimum",

test/Microsoft.OpenApi.Readers.Tests/ParseNodes/ParserHelperTests.cs

@@ -0,0 +1,24 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT license.
+
+using Microsoft.OpenApi.Readers.ParseNodes;
+using Xunit;
+
+namespace Microsoft.OpenApi.Readers.Tests.ParseNodes
+{
+    [Collection("DefaultSettings")]
+    public class ParserHelperTests
+    {
+        [Fact]
+        public void ParseDecimalWithFallbackOnOverflow_ReturnsParsedValue()
+        {
+            Assert.Equal(23434, ParserHelper.ParseDecimalWithFallbackOnOverflow("23434", 10));
+        }
+
+        [Fact]
+        public void ParseDecimalWithFallbackOnOverflow_Overflows_ReturnsFallback()
+        {
+            Assert.Equal(10, ParserHelper.ParseDecimalWithFallbackOnOverflow(double.MaxValue.ToString(), 10));
+        }
+    }
+}