OAuth2 Xojo Plugin Reference Documentation

OAuth2

Current Version: 9.5.0.73

Implements OAuth2 authorization for desktop (installed) applications, scripts, etc. These are applications that run on a computer where it is possible to popup a browser window, or embed a browser window, to allow the end-user to interactively grant or deny authentication.

In OAuth 2.0 terms, the application is considered to be a "public" client type, or a "native application". (In OAuth 2.0 terminology, a fully managed .NET desktop application is still a "native application".) This OAuth2 API helps implement the "Authorization Code Grant" flow to obtain both access tokens and refresh tokens. See Section 4.1 of RFC 6749.

In other commonly used terminology, this OAuth2 class helps to implement "Three Legged" OAuth2 Authorization. See http://oauthbible.com/#oauth-2-three-legged

Object Creation

Dim oAuth2 As New Chilkat.OAuth2

Properties

AccessToken
AccessToken As String
Introduced in version 9.5.0.59

When the OAuth2 three-legged authorization has successfully completed in the background thread, this property contains the access_token.

For example, a successful Google API JSON response looks like this:

 {
             "access_token": "ya29.Ci9ZA-Z0Q7vtnch8xxxxxxxxxxxxxxgDVOOV97-IBvTt958xxxxxx1sasw",
             "token_type": "Bearer",

            "expires_in": 3600,

            "refresh_token": "1/fYjEVR-3Oq9xxxxxxxxxxxxxxLzPtlNOeQ"
}

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AccessTokenResponse
AccessTokenResponse As String (read-only)
Introduced in version 9.5.0.59

When the OAuth2 three-legged authorization has completed in the background thread, this property contains the response that contains the access_token, the optional refresh_token, and any other information included in the final response. If the authorization was denied, then this contains the error response.

For example, a successful JSON response for a Google API looks like this:

 {
             "access_token": "ya29.Ci9ZA-Z0Q7vtnch8xxxxxxxxxxxxxxgDVOOV97-IBvTt958xxxxxx1sasw",
             "token_type": "Bearer",

            "expires_in": 3600,

            "refresh_token": "1/fYjEVR-3Oq9xxxxxxxxxxxxxxLzPtlNOeQ"
}

Note: Not all responses are JSON. A successful Facebook response is plain text and looks like this:

access_token=EAAZALuOC1wAwBAKH6FKnxOkjfEP ... UBZBhYD5hSVBETBx6AZD&expires=5134653

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AppCallbackUrl
AppCallbackUrl As String
Introduced in version 9.5.0.73

Some OAuth2 services, such as QuickBooks, do not allow for "http://localhost:port" callback URLs. When this is the case, a desktop app cannot pop up a browser and expect to get the final redirect callback. The workaround is to set this property to a URI on your web server, which sends a response to redirect back to "http://localhost:3017". Thus the callback becomes a double redirect, which ends at localhost:port, and thus completes the circuit.

If the OAuth2 service allows for "http://localhost:port" callback URLs, then leave this property empty.

As an example, one could set this property to "https://www.yourdomain.com/OAuth2.php", where the PHP source contains the following:

<?php
  header( 'Location: http://localhost:3017?' . $_SERVER['QUERY_STRING'] );
?>

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AuthFlowState
AuthFlowState As Int32 (read-only)
Introduced in version 9.5.0.59

Indicates the current progress of the OAuth2 three-legged authorization flow. Possible values are:

0: Idle. No OAuth2 has yet been attempted.
1: Waiting for Redirect. The OAuth2 background thread is waiting to receive the redirect HTTP request from the browser.
2: Waiting for Final Response. The OAuth2 background thread is waiting for the final access token response.
3: Completed with Success. The OAuth2 flow has completed, the background thread exited, and the successful JSON response is available in AccessTokenResponse property.
4: Completed with Access Denied. The OAuth2 flow has completed, the background thread exited, and the error JSON is available in AccessTokenResponse property.
5: Failed Prior to Completion. The OAuth2 flow failed to complete, the background thread exited, and the error information is available in the FailureInfo property.

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AuthorizationEndpoint
AuthorizationEndpoint As String
Introduced in version 9.5.0.59

The URL used to obtain an authorization grant. For example, the Google APIs authorization endpoint is "https://accounts.google.com/o/oauth2/v2/auth". (In three-legged OAuth2, this is the very first point of contact that begins the OAuth2 authentication flow.)

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ClientId
ClientId As String
Introduced in version 9.5.0.59

The "client_id" that identifies the application.

For example, if creating an app to use a Google API, one would create a client ID by:

  1. Logging into the Google API Console (https://console.developers.google.com).
  2. Navigate to "Credentials".
  3. Click on "Create Credentials"
  4. Choose "OAuth client ID"
  5. Select the "Other" application type.
  6. Name your app and click "Create", and a client_id and client_secret will be generated.
Other API's, such as Facebook, should have something similar for generating a client ID and client secret.

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ClientSecret
ClientSecret As String
Introduced in version 9.5.0.59

The "client_secret" for the application. Application credentials (i.e. what identifies the application) consist of a client_id and client_secret. See the ClientId property for more information.

Is the Client Secret Really a Secret?

This deserves some explanation. For a web-based application (where the code is on the web server) and the user interacts with the application in a browser, then YES, the client secret MUST be kept secret at all times. One does not want to be interacting with a site that claims to be "Application XYZ" but is actually an impersonator. But the Chilkat OAuth2 class is for desktop applications and scripts (i.e. things that run on the local computer, not in a browser).

Consider Mozilla Thunderbird. It is an application installed on your computer. Thunderbird uses OAuth2 authentication for GMail accounts in the same way as this OAuth2 API. When you add a GMail account and need to authenticate for the 1st time, you'll get a popup window (a browser) where you interactively grant authorization to Thunderbird. You implicitly know the Thunderbird application is running because you started it. There can be no impersonation unless your computer has already been hacked and when you thought you started Thunderbird, you actually started some rogue app. But if you already started some rogue app, then all has already been lost.

It is essentially impossible for desktop applications to embed a secret key (such as the client secret) and assure confidentiality (i.e. that the key cannot be obtained by some hacker. An application can hide the secret, and can make it difficult to access, but in the end the secret cannot be assumed to be safe. Therefore, the client_secret, for desktop (installed) applications is not actually secret. One should still take care to shroud the client secret to some extent, but know that whatever is done cannot be deemed secure. But this is OK. The reason it is OK is that implicitly, when a person starts an application (such as Thunderbird), the identity of the application is known. If a fake Thunderbird was started, then all has already been lost. The security of the system is in preventing the fake/rogue applications in the 1st place. If that security has already been breached, then nothing else really matters.

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CodeChallenge
CodeChallenge As Boolean
Introduced in version 9.5.0.59

Optional. Set this to True to send a code_challenge (as per RFC 7636) with the authorization request. The default value is False.

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CodeChallengeMethod
CodeChallengeMethod As String
Introduced in version 9.5.0.59

Optional. Only applies when the CodeChallenge property is set to True. Possible values are "plain" or "S256". The default is "S256".

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DebugLogFilePath
DebugLogFilePath As String

If set to a file path, causes each Chilkat method or property call to automatically append it's LastErrorText to the specified log file. The information is appended such that if a hang or crash occurs, it is possible to see the context in which the problem occurred, as well as a history of all Chilkat calls up to the point of the problem. The VerboseLogging property can be set to provide more detailed information.

This property is typically used for debugging the rare cases where a Chilkat method call hangs or generates an exception that halts program execution (i.e. crashes). A hang or crash should generally never happen. The typical causes of a hang are:

  1. a timeout related property was set to 0 to explicitly indicate that an infinite timeout is desired,
  2. the hang is actually a hang within an event callback (i.e. it is a hang within the application code), or
  3. there is an internal problem (bug) in the Chilkat code that causes the hang.

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FailureInfo
FailureInfo As String (read-only)
Introduced in version 9.5.0.59

If the OAuth2 three-legged authorization failed prior to completion (the AuthFlowState = 5), then information about the failure is contained in this property. This property is automatically cleared when OAuth2 authorization starts (i.e. when StartAuth is called).

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LastErrorHtml
LastErrorHtml As String (read-only)

Provides information in HTML format about the last method/property called. If a method call returns a value indicating failure, or behaves unexpectedly, examine this property to get more information.

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LastErrorText
LastErrorText As String (read-only)

Provides information in plain-text format about the last method/property called. If a method call returns a value indicating failure, or behaves unexpectedly, examine this property to get more information.

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LastErrorXml
LastErrorXml As String (read-only)

Provides information in XML format about the last method/property called. If a method call returns a value indicating failure, or behaves unexpectedly, examine this property to get more information.

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LastMethodSuccess
LastMethodSuccess As Boolean
Introduced in version 9.5.0.52

Indicate whether the last method call succeeded or failed. A value of True indicates success, a value of False indicates failure. This property is automatically set for method calls. It is not modified by property accesses. The property is automatically set to indicate success for the following types of method calls:

  • Any method that returns a string.
  • Any method returning a Chilkat object, binary bytes, or a date/time.
  • Any method returning a standard boolean status value where success = True and failure = False.
  • Any method returning an integer where failure is defined by a return value less than zero.

Note: Methods that do not fit the above requirements will always set this property equal to True. For example, a method that returns no value (such as a "void" in C++) will technically always succeed.

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ListenPort
ListenPort As Int32
Introduced in version 9.5.0.59

The port number to listen for the redirect URI request sent by the browser. If set to 0, then a random unused port is used. The default value of this property is 0.

In most cases, using a random unused port is the best choice. In some OAuth2 situations, such as with Facebook, a specific port number must be chosen. This is due to the fact that Facebook requires an APP to have a Site URL, which must exactly match the redirect_uri used in OAuth2 authorization. For example, the Facebook Site URL might be "http://localhost:3017/" if port 3017 is the listen port.

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ListenPortRangeEnd
ListenPortRangeEnd As Int32
Introduced in version 9.5.0.69

If set, then an unused port will be chosen in the range from the ListenPort property to this property. Some OAuth2 services, such as Google, require that callback URL's, including port numbers, be selected in advance. This feature allows for a range of callback URL's to be specified to cope with the possibility that another application on the same computer might be using a particular port.

For example, a Google ClientID might be configured with a set of authorized callback URI's such as:

  • http://localhost:55110/
  • http://localhost:55112/
  • http://localhost:55113/
  • http://localhost:55114/
  • http://localhost:55115/
  • http://localhost:55116/
  • http://localhost:55117/

In which case the ListenPort property would be set to 55110, and this property would be set to 55117.

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LocalHost
LocalHost As String
Introduced in version 9.5.0.59

Defaults to "localhost". This should typically remain at the default value. It is the loopback domain or IP address used for the redirect_uri. For example, "http://localhost:2012/". (assuming 2012 was used or randomly chosen as the listen port number) If the desired redirect_uri is to be "http://127.0.0.1:2012/", then set this property equal to "127.0.0.1".

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RedirectAllowHtml
RedirectAllowHtml As String
Introduced in version 9.5.0.59

The HTML returned to the browser when access is allowed by the end-user. The default value is HTMl that contains a META refresh to https://www.chilkatsoft.com/oauth2_allowed.html. Your application should set this property to display whatever HTML is desired when access is granted.

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RedirectDenyHtml
RedirectDenyHtml As String
Introduced in version 9.5.0.59

The HTML returned to the browser when access is denied by the end-user. The default value is HTMl that contains a META refresh to https://www.chilkatsoft.com/oauth2_denied.html. Your application should set this property to display whatever HTML is desired when access is denied.

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RefreshToken
RefreshToken As String
Introduced in version 9.5.0.59

When the OAuth2 three-legged authorization has successfully completed in the background thread, this property contains the refresh_token, if present.

For example, a successful Google API JSON response looks like this:

 {
             "access_token": "ya29.Ci9ZA-Z0Q7vtnch8xxxxxxxxxxxxxxgDVOOV97-IBvTt958xxxxxx1sasw",
             "token_type": "Bearer",

            "expires_in": 3600,

            "refresh_token": "1/fYjEVR-3Oq9xxxxxxxxxxxxxxLzPtlNOeQ"
}

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Resource
Resource As String
Introduced in version 9.5.0.67

This is an optional setting that defines the "resource" query parameter. For example, to call the Microsoft Graph API, set this property value to "https://graph.microsoft.com/". The Microsoft Dynamics CRM OAuth authentication also requires the Resource property.

More Information and Examples
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Scope
Scope As String
Introduced in version 9.5.0.59

This is an optional setting that defines the scope of access. For example, Google API scopes are listed here: https://developers.google.com/identity/protocols/googlescopes

For example, if wishing to grant OAuth2 authorization for Google Drive, one would set this property to "https://www.googleapis.com/auth/drive".

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TokenEndpoint
TokenEndpoint As String
Introduced in version 9.5.0.59

The URL for exchanging an authorization grant for an access token. For example, the Google APIs token endpoint is "https://www.googleapis.com/oauth2/v4/token". (In three-legged OAuth2, this is the very last point of contact that ends the OAuth2 authentication flow.)

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TokenType
TokenType As String
Introduced in version 9.5.0.59

When the OAuth2 three-legged authorization has successfully completed in the background thread, this property contains the token_type, if present.

A successful Google API JSON response looks like this:

 {
             "access_token": "ya29.Ci9ZA-Z0Q7vtnch8xxxxxxxxxxxxxxgDVOOV97-IBvTt958xxxxxx1sasw",
             "token_type": "Bearer",

            "expires_in": 3600,

            "refresh_token": "1/fYjEVR-3Oq9xxxxxxxxxxxxxxLzPtlNOeQ"
}

Note: Some responses may not included a "token_type" param. In that case, this property will remain empty.

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UseBasicAuth
UseBasicAuth As Boolean
Introduced in version 9.5.0.73

If set to True, then the internal POST (on the background thread) that exchanges the code for an access token will send the client_id/client_secret in an "Authorization Basic ..." header where the client_id is the login and the client_secret is the password.

Some services, such as fitbit.com, require the client_id/client_secret to be passed in this way.

The default value of this property is False, which causes the client_id/client_secret to be sent as query params.

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VerboseLogging
VerboseLogging As Boolean

If set to True, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. The default value is False. Verbose logging should only be used for debugging. The potentially large quantity of logged information may adversely affect peformance.

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Version
Version As String (read-only)

Version of the component/library, such as "9.5.0.63"

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Methods

Cancel
Function Cancel() As Boolean
Introduced in version 9.5.0.59

Cancels an OAuth2 authorization flow that is in progress.

Returns True for success, False for failure.

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GetRedirectRequestParam
Function GetRedirectRequestParam(paramName As String) As String
Introduced in version 9.5.0.69

Some OAuth2 providers can provide additional parameters in the redirect request sent to the local listener (i.e. the Chilkat background thread). One such case is for QuickBooks, It contains a realmId parameter such as the following:

http://localhost:55568/?state=xxxxxxxxxxxx&code=xxxxxxxxxxxx&realmId=1234567890

After the OAuth2 authentication is completed, an application can call this method to get any of the parameter values. For example, to get the realmId value, pass "realmId" in paramName.

Returns Nil on failure

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Monitor
Function Monitor() As Boolean
Introduced in version 9.5.0.59

Monitors an already started OAuth2 authorization flow and returns when it is finished.

Note: It rarely makes sense to call this method. If this programming language supports callbacks, then MonitorAsync is a better choice. (See the Oauth2 project repositories at https://github.com/chilkatsoft for samples.) If a programming language does not have callbacks, a better choice is to periodically check the AuthFlowState property for a value >= 3. If there is no response from the browser, the background thread (that is waiting on the browser) can be cancelled by calling the Cancel method.

Returns True for success, False for failure.

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MonitorAsync (1)
Function MonitorAsync() As Chilkat.Task
Introduced in version 9.5.0.59

Creates an asynchronous task to call the Monitor method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)

Note: Async method event callbacks happen in the background thread. Accessing and updating UI elements existing in the main thread may require special considerations.

Returns Nil on failure

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RefreshAccessToken
Function RefreshAccessToken() As Boolean
Introduced in version 9.5.0.59

Sends a refresh request to the token endpoint to obtain a new access token. After a successful refresh request, the AccessToken and RefreshToken properties will be updated with new values.

Note: This method can only be called if the ClientId, ClientSecret, RefreshToken and TokenEndpoint properties contain valid values.

Returns True for success, False for failure.

More Information and Examples
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RefreshAccessTokenAsync (1)
Function RefreshAccessTokenAsync() As Chilkat.Task
Introduced in version 9.5.0.59

Creates an asynchronous task to call the RefreshAccessToken method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)

Note: Async method event callbacks happen in the background thread. Accessing and updating UI elements existing in the main thread may require special considerations.

Returns Nil on failure

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SaveLastError
Function SaveLastError(path As String) As Boolean

Saves the last-error information (the contents of LastErrorXml) to an XML formatted file.

Returns True for success, False for failure.

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SleepMs
Sub SleepMs(millisec As Int32)
Introduced in version 9.5.0.59

Convenience method to force the calling thread to sleep for a number of milliseconds.

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StartAuth
Function StartAuth() As String
Introduced in version 9.5.0.59

Initiates the three-legged OAuth2 flow. The various properties, such as ClientId, ClientSecret, Scope, CodeChallenge, AuthorizationEndpoint, and TokenEndpoint, should be set prior to calling this method.

This method does two things:

  1. Forms and returns a URL that is to be loaded in a browser.
  2. Starts a background thread that listens on a randomly selected unused port to receive the redirect request from the browser. The receiving of the request from the browser, and the sending of the HTTP request to complete the three-legged OAuth2 flow is done entirely in the background thread. The application controls this behavior by setting the various properties beforehand.
The return value is the URL to be loaded (navigated to) in a popup or embedded browser.

Returns Nil on failure

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UseConnection
Function UseConnection(sock As Chilkat.Socket) As Boolean
Introduced in version 9.5.0.59

Calling this method is optional, and is only required if a proxy (HTTP or SOCKS), an SSH tunnel, or if special connection related socket options need to be used. When UseConnection is not called, the connection to the token endpoint is a direct connection using TLS (or not) based on the TokenEndpoint. (If the TokenEndpoint begins with "https://", then TLS is used.)

This method sets the socket object to be used for sending the requests to the token endpoint in the background thread. The sock can be an already-connected socket, or a socket object that is not yet connected. In some cases, such as for a connection through an SSH tunnel, the sock must already be connected. In other cases, an unconnected sock can be provided because the purpose for providing the socket object is to specify settings such as for HTTP or SOCKS proxies.

Returns True for success, False for failure.

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Events

To implement events, your application would define and implement a class that is a subclass of Chilkat.OAuth2. Your custom class would implement (i.e. override) some or all of the event methods.

For example:

class MyOAuth2
    Inherits Chilkat.OAuth2

    Function AbortCheck() As Boolean

    Sub BinaryData(data As MemoryBlock)

    Function PercentDone(pctDone As Int32) As Boolean

    Sub ProgressInfo(name As String, value As String)

    Sub TaskCompleted(task As Chilkat.Task)

    Sub TextData(data As String)


End Class
AbortCheck
Function AbortCheck() As Boolean

Provides the opportunity for a method call to be aborted. The AbortCheck event is fired periodically based on the value of the HeartbeatMs property. If HeartbeatMs is 0, then no AbortCheck events will fire. As an example, to fire 5 AbortCheck events per second, set the HeartbeatMs property equal to 200.

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PercentDone
Function PercentDone(pctDone As Int32) As Boolean

Provides the percentage completed for any method that involves network communications or time-consuming processing (assuming it is a method where a percentage completion can be measured). This event is only fired when it is possible to know a percentage completion, and when it makes sense to express the operation as a percentage completed. The pctDone argument will have a value from 1 to 100. For operations (Chilkat method calls) that complete very quickly, the number of PercentDone callbacks will vary, but the final callback should have a value of 100. For long running operations, no more than one callback per percentage point will occur (for example: 1, 2, 3, ... 98, 99, 100).

The PercentDone callback counts as an AbortCheck event. For method calls that complete quickly such that PercentDone events fire, it may be that AbortCheck events don't fire because the opportunity to abort is already provided in the PercentDone callback. For time consuming operations, where the amount of time between PercentDone callbacks are long, AbortCheck callbacks may be used to allow for the operation to be aborted in a more responsive manner.

The abort output argument provides a means for aborting the operation. Setting it to True will cause the method to abort and return a failed status (or whatever return value indicates failure).

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ProgressInfo
Sub ProgressInfo(name As String, value As String)

A general name/value event that provides information about what is happening during a method call. To find out what information is available, write code to handle this event and log the name/value pairs. Most are self-explanatory.

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TaskCompleted
Sub TaskCompleted(task As Chilkat.Task)

Called in the background thread when an asynchronous task completes.

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