System.Security.Permissions.SiteIdentityPermission Class

Summary

Defines the identity permission for the Web site from which the code originates. This class cannot be inherited.

C# Syntax:

[Serializable] public sealed class SiteIdentityPermission : CodeAccessPermission

Using this class, it is possible to ensure that callers are from a specific Web site. Site identity is only defined for code from URLs with the protocols of HTTP, HTTPS, and FTP. A site is the string between the "//" after the protocol of a URL and the following "/", if present, for example, www.fourthcoffee.com in the URL http://www.fourthcoffee.com/process/grind.htm. This excludes port numbers. If a given URL is http://www.fourthcoffee.com:8000/, the site is www.fourthcoffee.com, not www.fourthcoffee.com:8000.

Sites can be matched exactly, or by a wildcard ("*") prefix at the dot delimiter. For example, the site name string *.fourthcoffee.com matches fourthcoffee.com as well as www.fourthcoffee.com. Without a wildcard, the site name must be a precise match. The site name string * will match any site, but will not match code that has no site evidence.

System.Security.Permissions Namespace See also:
MSDN: permissions | MSDN: requestingpermissions | SiteIdentityPermissionAttribute | Site | SiteMembershipCondition

System.Security.Permissions.SiteIdentityPermission Member List:

Public Constructors

ctor #1	Overloaded: .ctor(PermissionState state) Initializes a new instance of the SiteIdentityPermission class with fully restricted PermissionState.
ctor #2	Overloaded: .ctor(string site) Initializes a new instance of the SiteIdentityPermission class to represent the specified site identity.

Public Properties

Site	Read-write Gets or sets the current site.

Public Methods

Assert (inherited from System.Security.CodeAccessPermission)	See base class member description: System.Security.CodeAccessPermission.Assert Asserts that calling code can access the resource identified by the current permission through the code that calls this method, even if callers higher in the stack have not been granted permission to access the resource.
Copy	Overridden: Creates and returns an identical copy of the current permission.
Demand (inherited from System.Security.CodeAccessPermission)	See base class member description: System.Security.CodeAccessPermission.Demand Forces a SecurityException at run time if all callers higher in the call stack have not been granted the permission specified by the current instance.
Deny (inherited from System.Security.CodeAccessPermission)	See base class member description: System.Security.CodeAccessPermission.Deny Prevents callers higher in the call stack from using the code that calls this method to access the resource specified by the current instance.
Equals (inherited from System.Object)	See base class member description: System.Object.Equals Derived from System.Object, the primary base class for all objects.
FromXml	Overridden: Reconstructs a permission with a specified state from an XML encoding.
GetHashCode (inherited from System.Object)	See base class member description: System.Object.GetHashCode Derived from System.Object, the primary base class for all objects.
GetType (inherited from System.Object)	See base class member description: System.Object.GetType Derived from System.Object, the primary base class for all objects.
Intersect	Overridden: Creates and returns a permission that is the intersection of the current permission and the specified permission.
IsSubsetOf	Overridden: Determines whether the current permission is a subset of the specified permission.
PermitOnly (inherited from System.Security.CodeAccessPermission)	See base class member description: System.Security.CodeAccessPermission.PermitOnly Prevents callers higher in the call stack from using the code that calls this method to access all resources except for the resource specified by the current instance.
ToString (inherited from System.Security.CodeAccessPermission)	See base class member description: System.Security.CodeAccessPermission.ToString Creates and returns a string representation of the current permission object.
ToXml	Overridden: Creates an XML encoding of the permission and its current state.
Union	Overridden: Creates a permission that is the union of the current permission and the specified permission.

Protected Methods

Finalize (inherited from System.Object)	See base class member description: System.Object.Finalize Derived from System.Object, the primary base class for all objects.
MemberwiseClone (inherited from System.Object)	See base class member description: System.Object.MemberwiseClone Derived from System.Object, the primary base class for all objects.

Hierarchy:

• System.Object
• System.Security.CodeAccessPermission
• System.Security.Permissions.SiteIdentityPermission

System.Security.Permissions.SiteIdentityPermission Member Details

Summary

Initializes a new instance of the SiteIdentityPermission class with fully restricted PermissionState.

C# Syntax:

public SiteIdentityPermission(    PermissionState state );

state

None is the only valid value for identity permissions.

Exceptions

Exception Type	Condition
ArgumentException	The state parameter is not a valid value of PermissionState.

The fully restricted state of SiteIdentityPermission matches no sites. This constructor is included for consistency with the design of other permissions, but is not useful in practice.

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Summary

Initializes a new instance of the SiteIdentityPermission class to represent the specified site identity.

C# Syntax:

public SiteIdentityPermission(    string site );

site

The site name or wildcard expression.

Exceptions

Exception Type	Condition
ArgumentException	The site parameter is not a valid string, or does not match a valid wildcard site name.

Site identity is only defined for code from URLs with the protocols of HTTP, HTTPS, and FTP. A site is the string between the "//" after the protocol of a URL and the following "/", if present, for example, www.fourthcoffee.com in the URL http://www.fourthcoffee.com/process/grind.htm/. This excludes port numbers. If a given URL is http://www.fourthcoffee.com:8000/, the site is www.fourthcoffee.com, not www.fourthcoffee.com:8000.

Sites can be matched exactly, or by a wildcard ("*") prefix at the dot delimiter. For example, the site name string *.fourthcoffee.com matches fourthcoffee.com as well as www.fourthcoffee.com. Without a wildcard, the site name must be a precise match.

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Summary

Gets or sets the current site.

C# Syntax:

public string Site {get; set;}

Site identity is only defined for code from URLs with the protocols of HTTP, HTTPS, and FTP. A site is the string between the "//" after the protocol of a URL and the following "/", if present, for example, www.fourthcoffee.com in the URL http://www.fourthcoffee.com/process/grind.htm/. This excludes port numbers. If a given URL is http://www.fourthcoffee.com:8000/, the site is www.fourthcoffee.com, not www.fourthcoffee.com:8000.

Sites can be matched exactly, or by a wildcard ("*") prefix at the dot delimiter. For example, the site name string *.fourthcoffee.com matches fourthcoffee.com as well as www.fourthcoffee.com. Without a wildcard, the site name must be a precise match. The site name string * will match any site, but will not match code that has no site evidence.

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Inherited
See base class member description: System.Security.CodeAccessPermission.Assert

Summary

Asserts that calling code can access the resource identified by the current permission through the code that calls this method, even if callers higher in the stack have not been granted permission to access the resource.

C# Syntax:

public void Assert();

Exceptions

Exception Type	Condition
SecurityException	The calling code does not have SecurityPermissionFlag.Assertion. -or- There is already an active CodeAccessPermission.Assert for the current frame.

Implements:

IStackWalk.Assert

The call stack is typically represented as growing down, so that methods higher in the call stack call methods lower in the call stack. Calling CodeAccessPermission.Assert prevents a stack walk originating lower in the call stack from proceeding up the call stack beyond the code that calls this method. Therefore, even if callers higher on the call stack do not have the requisite permissions to access a resource, they can still access it through the code that calls this method on the necessary permission. An assertion is effective only if the code that calls CodeAccessPermission.Assert passes the security check for the permission that it is asserting.

The call to CodeAccessPermission.Assert is effective until the calling code returns to its caller. Only one CodeAccessPermission.Assert can be active on a frame. An attempt to call CodeAccessPermission.Assert when an active CodeAccessPermission.Assert exists on the frame results in a SecurityException. Call CodeAccessPermission.RevertAssert or CodeAccessPermission.RevertAll to remove an active CodeAccessPermission.Assert.

CodeAccessPermission.Assert is ignored for a permission not granted because a demand for that permission will not succeed. However, if code lower on the call stack calls CodeAccessPermission.Demand for that permission, a SecurityException is thrown when the stack walk reaches the code that tried to call CodeAccessPermission.Assert. This happens because the code that called CodeAccessPermission.Assert has not been granted the permission, even though it tried to CodeAccessPermission.Assert it.

Because calling CodeAccessPermission.Assert removes the requirement that all code in the call chain must be granted permission to access the specified resource, it can open up security vulnerabilities if used incorrectly or inappropriately. Therefore, it should be used with great caution.

Notes to inheritors: You cannot override this method.

SecurityPermission for the ability to call CodeAccessPermission.Assert. Associated enumeration: SecurityPermissionFlag.Assertion

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Summary

Creates and returns an identical copy of the current permission.

C# Syntax:

public override IPermission Copy();

Return Value:

A copy of the current permission.

Implements:

IPermission.Copy

A copy of the permission represents the same access to resources or the same site identity as the original permission.

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Inherited
See base class member description: System.Security.CodeAccessPermission.Demand

Summary

Forces a SecurityException at run time if all callers higher in the call stack have not been granted the permission specified by the current instance.

C# Syntax:

public void Demand();

Exceptions

Exception Type	Condition
SecurityException	A caller higher in the call stack does not have the permission specified by the current instance. -or- A caller higher in the call stack has called CodeAccessPermission.Deny on the current permission object.

Implements:

IPermission.Demand

Implements:

IStackWalk.Demand

This method is typically used by secure libraries to ensure that callers have permission to access a resource. For example, a file class in a secure class library calls CodeAccessPermission.Demand for the necessary FileIOPermission before performing a file operation requested by the caller.

The permissions of the code that calls this method are not examined; the check begins from the immediate caller of that code and proceeds up the stack. The call stack is typically represented as growing down, so that methods higher in the call stack call methods lower in the call stack. CodeAccessPermission.Demand succeeds only if no SecurityException is raised.

Notes to inheritors: You cannot override this method.

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Inherited
See base class member description: System.Security.CodeAccessPermission.Deny

Summary

Prevents callers higher in the call stack from using the code that calls this method to access the resource specified by the current instance.

C# Syntax:

public void Deny();

Exceptions

Exception Type	Condition
SecurityException	There is already an active CodeAccessPermission.Deny for the current frame.

Implements:

IStackWalk.Deny

This method prevents callers higher in the call stack from accessing the protected resource through the code that calls this method, even if those callers have been granted permission to access it. The call stack is typically represented as growing down, so that methods higher in the call stack call methods lower in the call stack.

CodeAccessPermission.Deny can limit the liability of the programmer or prevent accidental security vulnerabilities because it prevents the method that calls CodeAccessPermission.Deny from being used to access the resource protected by the denied permission. If a method calls CodeAccessPermission.Deny on a permission, and if a CodeAccessPermission.Demand for that permission is invoked by a caller lower in the call stack, that security check will fail when it reaches the CodeAccessPermission.Deny.

The call to CodeAccessPermission.Deny is effective until the calling code returns to its caller. Only one CodeAccessPermission.Deny can be active on a frame. An attempt to call CodeAccessPermission.Deny when an active CodeAccessPermission.Deny exists on the frame results in a SecurityException. Call CodeAccessPermission.RevertDeny or CodeAccessPermission.RevertAll to remove an active CodeAccessPermission.Deny. CodeAccessPermission.Deny is ignored for a permission not granted because a demand for that permission will not succeed.

Notes to inheritors: You cannot override this method.

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Inherited
See base class member description: System.Object.Equals

C# Syntax:

public virtual bool Equals(    object obj );

For more information on members inherited from System.Object click on the link above.

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Inherited
See base class member description: System.Object.Finalize

C# Syntax:

~SiteIdentityPermission();

For more information on members inherited from System.Object click on the link above.

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Summary

Reconstructs a permission with a specified state from an XML encoding.

C# Syntax:

public override void FromXml(    SecurityElement esd );

esd

The XML encoding to use to reconstruct the permission.

Exceptions

Exception Type	Condition
ArgumentNullException	The esd parameter is null.
ArgumentException	The esd parameter is not a valid permission element. -or- The esd parameter's version number is not valid.

Implements:

ISecurityEncodable.FromXml

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Inherited
See base class member description: System.Object.GetHashCode

C# Syntax:

public virtual int GetHashCode();

For more information on members inherited from System.Object click on the link above.

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Inherited
See base class member description: System.Object.GetType

C# Syntax:

public Type GetType();

For more information on members inherited from System.Object click on the link above.

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Summary

Creates and returns a permission that is the intersection of the current permission and the specified permission.

C# Syntax:

public override IPermission Intersect(    IPermission target );

target

A permission to intersect with the current permission. It must be of the same type as the current permission.

Return Value:

A new permission that represents the intersection of the current permission and the specified permission. This new permission is null if the intersection is empty.

Exceptions

Exception Type	Condition
ArgumentException	The target parameter is not null and is not of the same type as the current permission.

Implements:

IPermission.Intersect

The intersection of two permissions is a permission that describes the set of operations they both describe in common. Only a demand that passes both original permissions will pass the intersection.

The intersection of two identical site identity permissions is the same permission. The intersection of two different (not wild card) expressions is an empty permission. The intersection of a wild card expression and a matching site is the site. The intersection of two wild card expressions that match is the longer, more specific of the two expressions.

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Summary

Determines whether the current permission is a subset of the specified permission.

C# Syntax:

public override bool IsSubsetOf(    IPermission target );

target

A permission that is to be tested for the subset relationship. This permission must be of the same type as the current permission.

Return Value:

true if the current permission is a subset of the specified permission; otherwise, false.

Exceptions

Exception Type	Condition
ArgumentException	The target parameter is not null and is not of the same type as the current permission.

Implements:

IPermission.IsSubsetOf

The current permission is a subset of the specified permission if the current permission specifies a set of operations that is wholly contained by the specified permission.

The following table shows the value of SiteIdentityPermission.IsSubsetOf for a range of values of the current permission and the specified permission.

Current Permission	Specified Permission	IsSubsetOf
www.fourthcoffee.com	www.fourthcoffee.com	true
www.fourthcoffee.com	www.tailspintoys.com	false
www.fourthcoffee.com	*.fourthcoffee.com	true
www.fourthcoffee.com	*.com	true
*.fourthcoffee.com	www.fourthcoffee.com	false
*.fourthcoffee.com	*.fourthcoffee.com	true
*.fourthcoffee.com	*.com	true
Anything except None	*	true
None	Anything	true

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Inherited
See base class member description: System.Object.MemberwiseClone

C# Syntax:

protected object MemberwiseClone();

For more information on members inherited from System.Object click on the link above.

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Inherited
See base class member description: System.Security.CodeAccessPermission.PermitOnly

Summary

Prevents callers higher in the call stack from using the code that calls this method to access all resources except for the resource specified by the current instance.

C# Syntax:

public void PermitOnly();

Exceptions

Exception Type	Condition
SecurityException	There is already an active CodeAccessPermission.PermitOnly for the current frame.

Implements:

IStackWalk.PermitOnly

CodeAccessPermission.PermitOnly is similar to CodeAccessPermission.Deny, in that both cause stack walks to fail when they would otherwise succeed. The difference is that CodeAccessPermission.Deny specifies permissions that will cause the stack walk to fail, but CodeAccessPermission.PermitOnly specifies the only permissions that do not cause the stack walk to fail.

Call this method to ensure that your code can be used to access only the specified resources. The call to CodeAccessPermission.PermitOnly is effective until the calling code returns to its caller. Only one CodeAccessPermission.PermitOnly can be active on a frame. An attempt to call CodeAccessPermission.PermitOnly when an active CodeAccessPermission.PermitOnly exists on the frame results in a SecurityException. Call CodeAccessPermission.RevertPermitOnly or CodeAccessPermission.RevertAll to remove an active CodeAccessPermission.PermitOnly.

CodeAccessPermission.PermitOnly is ignored for a permission not granted because a demand for that permission will not succeed. However, if code lower on the call stack later calls CodeAccessPermission.Demand for that permission, a SecurityException is thrown when the stack walk reaches the code that tried to call CodeAccessPermission.PermitOnly. This is because the code that called CodeAccessPermission.PermitOnly has not been granted the permission, even though it called CodeAccessPermission.PermitOnly for that permission. The call stack is typically represented as growing down, so that methods higher in the call stack call methods lower in the call stack.

Notes to inheritors: You cannot override this method.

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Inherited
See base class member description: System.Security.CodeAccessPermission.ToString

Summary

Creates and returns a string representation of the current permission object.

C# Syntax:

public override string ToString();

Return Value:

A string representation of the current permission object.

This method is useful in debugging when you need to display the permission as a string.

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Summary

Creates an XML encoding of the permission and its current state.

C# Syntax:

public override SecurityElement ToXml();

Return Value:

An XML encoding of the permission, including any state information.

Implements:

ISecurityEncodable.ToXml

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Summary

Creates a permission that is the union of the current permission and the specified permission.

C# Syntax:

public override IPermission Union(    IPermission target );

target

A permission to combine with the current permission. It must be of the same type as the current permission.

Return Value:

A new permission that represents the union of the current permission and the specified permission.

Exceptions

Exception Type	Condition
ArgumentException	The target parameter is not null and is not of the same type as the current permission.

Implements:

IPermission.Union

The result of a call to SiteIdentityPermission.Union is a permission that represents all the operations represented by both the current permission and the specified permission. Any demand that passes either permission passes their union.

The union of a permission and null is the permission that is not null. The union of a permission and a subset of that permission is the permission that contains the other. Any other combination results in a permission that is null. For example, the union of the site identity www.fourthcoffee.com and the site identity www.tailspintoys.com is null because neither is a subset of the other.

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