Uri parameters should not be strings

TypeName	UriParametersShouldNotBeStrings
CheckId	CA1054
Category	Microsoft.Design
Breaking Change	Breaking

Cause

A type declares a method with a string parameter whose name contains "uri", "Uri", "urn", "Urn", "url", or "Url"; and the type does not declare a corresponding overload that takes a System.Uri parameter.

Rule Description

This rule splits the parameter name into tokens based on the camel casing convention and checks whether each token equals "uri", "Uri", "urn", "Urn", "url", or "Url". If there is a match, the rule assumes that the parameter represents a uniform resource identifier (URI). A string representation of a URI is prone to parsing and encoding errors, and can lead to security vulnerabilities. If a method takes a string representation of a URI, a corresponding overload should be provided that takes an instance of the Uri class, which provides these services in a safe and secure manner.

How to Fix Violations

To fix a violation of this rule, change the parameter to a Uri type; this is a breaking change. Alternately, provide an overload of the method which takes a Uri parameter; this is a non-breaking change.

When to Exclude Warnings

It is safe to exclude a warning from this rule if the parameter does not represent a URI.

Example

The following example shows a type, ErrorProne, that violates this rule, and a type, SaferWay, that satisfies the rule.

Imports System

Namespace DesignLibrary

   Public Class ErrorProne
   
      Dim someUriValue As String 

      ' Violates rule UriPropertiesShouldNotBeStrings.
      Property SomeUri As String
         Get 
            Return someUriValue 
         End Get
         Set 
            someUriValue = Value 
         End Set
      End Property

      ' Violates rule UriParametersShouldNotBeStrings.
      Sub AddToHistory(uriString As String)
      End Sub

      ' Violates rule UriReturnValuesShouldNotBeStrings.
      Function GetRefererUri(httpHeader As String) As String
         Return "https://www.adventure-works.com"
      End Function

   End Class

   Public Class SaferWay
   
      Dim someUriValue As Uri 

      ' To retrieve a string, call SomeUri.ToString().
      ' To set using a string, call SomeUri = New Uri(string).
      Property SomeUri As Uri
         Get 
            Return someUriValue 
         End Get
         Set 
            someUriValue = Value 
         End Set
      End Property

      Sub AddToHistory(uriString As String)
         ' Check for UriFormatException.
         AddToHistory(New Uri(uriString))
      End Sub

      Sub AddToHistory(uriString As Uri)
      End Sub

      Function GetRefererUri(httpHeader As String) As Uri
         Return New Uri("https://www.adventure-works.com")
      End Function

   End Class

End Namespace

using System;

namespace DesignLibrary
{
   public class ErrorProne
   {
      string someUri;

      // Violates rule UriPropertiesShouldNotBeStrings.
      public string SomeUri
      {
         get { return someUri; }
         set { someUri = value; }
      }

      // Violates rule UriParametersShouldNotBeStrings.
      public void AddToHistory(string uriString) { }

      // Violates rule UriReturnValuesShouldNotBeStrings.
      public string GetRefererUri(string httpHeader)
      {
         return "https://www.adventure-works.com";
      }
   }

   public class SaferWay
   {
      Uri someUri;

      // To retrieve a string, call SomeUri.ToString().
      // To set using a string, call SomeUri = new Uri(string).
      public Uri SomeUri
      {
         get { return someUri; }
         set { someUri = value; }
      }

      public void AddToHistory(string uriString)
      {
         // Check for UriFormatException.
         AddToHistory(new Uri(uriString));
      }

      public void AddToHistory(Uri uriType) { }

      public Uri GetRefererUri(string httpHeader)
      {
         return new Uri("https://www.adventure-works.com");
      }
   }
}

#using <system.dll>
using namespace System;

namespace DesignLibrary
{
   public ref class ErrorProne
   {
   public:
      // Violates rule UriPropertiesShouldNotBeStrings.
      property String^ SomeUri;

      // Violates rule UriParametersShouldNotBeStrings.
      void AddToHistory(String^ uriString) { }

      // Violates rule UriReturnValuesShouldNotBeStrings.
      String^ GetRefererUri(String^ httpHeader)
      {
         return "https://www.adventure-works.com";
      }
   };

   public ref class SaferWay
   {
   public:
      // To retrieve a string, call SomeUri()->ToString().
      // To set using a string, call SomeUri(gcnew Uri(string)).
      property Uri^ SomeUri;

      void AddToHistory(String^ uriString)
      {
         // Check for UriFormatException.
         AddToHistory(gcnew Uri(uriString));
      }

      void AddToHistory(Uri^ uriType) { }

      Uri^ GetRefererUri(String^ httpHeader)
      {
         return gcnew Uri("https://www.adventure-works.com");
      }
   };
}

Related Rules

Uri properties should not be strings

Uri return values should not be strings

Pass system uri objects instead of strings

String uri overloads call system uri overloads