Using JwtConstants.MaxJwtSegmentCount to prevent possible performance…

… issues
AzureAD · Dec 9, 2019 · 408194d · 408194d
1 parent ef0e716
commit 408194d
Showing 1 changed file with 4 additions and 6 deletions.
diff --git a/src/Microsoft.IdentityModel.JsonWebTokens/JsonWebToken.cs b/src/Microsoft.IdentityModel.JsonWebTokens/JsonWebToken.cs
@@ -56,13 +56,11 @@ public JsonWebToken(string jwtEncodedString)
             if (string.IsNullOrEmpty(jwtEncodedString))
                 throw new ArgumentNullException(nameof(jwtEncodedString));
 
-            // Number of segments is always one more than the number of '.'s.
-            var count = jwtEncodedString.Count(c => c == '.') + 1;
-            if (count == JwtConstants.JwsSegmentCount || count == JwtConstants.JweSegmentCount)
-            {
-                var tokenParts = jwtEncodedString.Split('.');
+            // Max number of segments is set to JwtConstants.MaxJwtSegmentCount + 1 so that we know if there were more than 5 segments present.
+            // In the case where JwtEncodedString has greater than 5 segments, the length of tokenParts will always be 6.
+            var tokenParts = jwtEncodedString.Split(new char[] { '.' }, JwtConstants.MaxJwtSegmentCount + 1);
+            if (tokenParts.Length == JwtConstants.JwsSegmentCount || tokenParts.Length == JwtConstants.JweSegmentCount)
                 Decode(tokenParts, jwtEncodedString);
-            }
             else
                 throw LogHelper.LogExceptionMessage(new ArgumentException(LogHelper.FormatInvariant(LogMessages.IDX14100, jwtEncodedString)));
         }