Obtain the access token from a Microsoft Azure Access Control Service (ACS) account that is associated with the customer's Microsoft Office 365 tenancy
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<# | |
.Synopsis | |
Obtain an app-only access token from ACS. | |
.DESCRIPTION | |
Retrieves an app-only access token from ACS to call the specified principal | |
at the specified targetHost. The targetHost must be registered for target principal. If specified realm is | |
null, the "Realm" setting in web.config will be used instead | |
.EXAMPLE | |
Get-SPOAccessToken -Url "https://contoso.sharepoint.com/_api/web" -ClientId "" -ClientSecret "" | |
#> | |
Function Get-SPOAccessToken([string]$ClientId,[string]$ClientSecret,[Uri]$WebUri){ | |
$SharePointPrincipal = "00000003-0000-0ff1-ce00-000000000000" | |
$realm = GetRealmFromTargetUrl -TargetApplicationUri $WebUri | |
$accessToken = GetAppOnlyAccessToken -ClientId $ClientId -ClientSecret $ClientSecret -TargetPrincipalName $SharePointPrincipal -TargetHost $WebUri.Authority -TargetRealm $realm | |
return $accessToken.access_token | |
} | |
function GetRealmFromTargetUrl([Uri]$TargetApplicationUri) | |
{ | |
$url = $WebUrl + "/_vti_bin/client.svc" | |
$headers = @{} | |
$headers.Add('Authorization','Bearer') | |
try { | |
$response = Invoke-WebRequest -Uri $TargetApplicationUri -Headers $headers -Method Get | |
} | |
catch [Net.WebException] { | |
$authResponseHeader = $_.Exception.Response.Headers["WWW-Authenticate"] | |
#$bearerKey = "Bearer realm=" | |
$bearer = $authResponseHeader.Split(",")[0] | |
$targetRealm = $bearer.Split("=")[1] | |
return $targetRealm.Substring(1,$targetRealm.Length-2) | |
} | |
return $null | |
} | |
Function GetAppOnlyAccessToken([string]$ClientId,[string]$ClientSecret,[string]$TargetPrincipalName,[string]$TargetHost,[string]$TargetRealm) | |
{ | |
$resource = GetFormattedPrincipal -PrincipalName $TargetPrincipalName -HostName $TargetHost -Realm $TargetRealm | |
$ClientId = GetFormattedPrincipal -PrincipalName $ClientId -Realm $TargetRealm | |
$contentType = 'application/x-www-form-urlencoded' | |
$stsUrl = GetSecurityTokenServiceUrl -Realm $TargetRealm | |
$oauth2Request = CreateAccessTokenRequestWithClientCredentials -ClientId $ClientId -ClientSecret $ClientSecret -Scope $resource | |
$oauth2Response = Invoke-RestMethod -Method Post -Uri $stsUrl -ContentType $contentType -Body $oauth2Request | |
return $oauth2Response | |
} | |
Function GetSecurityTokenServiceUrl([string]$Realm) | |
{ | |
return "https://accounts.accesscontrol.windows.net/$Realm/tokens/OAuth/2" | |
} | |
Function CreateAccessTokenRequestWithClientCredentials([string]$ClientId,[string]$ClientSecret,[string]$Scope) | |
{ | |
$oauth2Request = @{ | |
'grant_type' = 'client_credentials'; | |
'client_id' = $ClientId; | |
'client_secret' = $ClientSecret; | |
'scope' = $Scope; | |
'resource' = $Scope | |
} | |
return $oauth2Request | |
} | |
function GetFormattedPrincipal([string]$PrincipalName, [string]$HostName, [string]$Realm) | |
{ | |
if ($HostName) | |
{ | |
return "$PrincipalName/$HostName@$Realm" | |
} | |
return "$PrincipalName@$Realm" | |
} |
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