Implement TenantUtil object with methods to extract tenant and tenantID from identifiers, Fixes AB#3370810

common4j/src/main/com/microsoft/identity/common/java/util/TenantUtil.kt

@@ -0,0 +1,87 @@
+//  Copyright (c) Microsoft Corporation.
+//  All rights reserved.
+//
+//  This code is licensed under the MIT License.
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files(the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions :
+//
+//  The above copyright notice and this permission notice shall be included in
+//  all copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+//  THE SOFTWARE.
+package com.microsoft.identity.common.java.util
+
+import com.microsoft.identity.common.java.authorities.AzureActiveDirectoryAudience
+import com.microsoft.identity.common.java.logging.Logger
+import com.microsoft.identity.common.java.providers.microsoft.azureactivedirectory.AzureActiveDirectory
+import java.util.regex.Matcher
+import java.util.regex.Pattern
+
+object TenantUtil {
+    private const val TAG: String = "TenantUtil"
+    private const val IDENTIFIER_REGEX: String = "(.*@.*|^[0-9A-Fa-f\\-]{36}$)"
+    private val PAIR_REGEX: Pattern = Pattern.compile(IDENTIFIER_REGEX)
+
+    /**
+     * Extracts tenant from an identifier.
+     *
+     * @param identifier {@link String} This could be an email address/UPN or a GUID (tenant ID).
+     * @return a tenant (hostname or tenant ID).
+     */
+    fun getTenantFromIdentifier(identifier: String?): String? {
+        if (identifier.isNullOrBlank()) {
+            return null
+        }
+        val matcher: Matcher = PAIR_REGEX.matcher(identifier)
+        if (!matcher.matches()) {
+            return null
+        }
+        // If identifier is a UPN, extracts a host from it.
+        if (identifier.contains("@")) {
+            return identifier.substring(identifier.indexOf("@") + 1).trim()
+        }
+        return identifier
+    }
+
+    /**
+     * Extracts tenant ID from login hint.
+     *
+     * @param loginHint {@link String} This could be an email address/UPN or a GUID (tenant ID).
+     * @param correlationId Correlation ID for the request to be logged.
+     * @return a tenant ID if found, null otherwise.
+     */
+    fun getTenantIdFromLoginHnt(loginHint: String?, correlationId : String?): String? {
+        val methodTag = "$TAG:getTenantIdFromLoginHnt"
+        if (loginHint.isNullOrBlank()) {
+            Logger.info(methodTag, correlationId, "Login hint is empty")
+            return null
+        }
+        val tenantName  = getTenantFromIdentifier(loginHint)
+        if (tenantName.isNullOrBlank()) {
+            Logger.warn(methodTag, correlationId, "Tenant name is empty")
+            return null
+        }
+        try {
+            val configuration =
+                AzureActiveDirectory.loadOpenIdProviderConfigurationMetadataForTenant(tenantName)
+            val tenantId =
+                AzureActiveDirectoryAudience.getTenantIdFromOpenIdProviderConfiguration(configuration)
+            Logger.info(methodTag, correlationId, "Successfully got tenant ID from login hint.")
+            return tenantId
+        } catch (e: Exception) {
+            Logger.error(methodTag, correlationId, "Failed to get tenant ID from login hint.", e)
+            return null
+        }
+    }
+}