[Backport] Added credential caching for Managed Identity Credential and Default Azure Credential (2415)

src/main/java/com/microsoft/sqlserver/jdbc/SQLServerSecurityUtility.java

@@ -6,17 +6,22 @@
 package com.microsoft.sqlserver.jdbc;
 
 import java.security.InvalidKeyException;
+import java.security.MessageDigest;
 import java.security.NoSuchAlgorithmException;
 import java.text.MessageFormat;
 import java.util.Arrays;
+import java.util.HashMap;
 import java.util.Optional;
 import java.util.Iterator;
 import java.util.List;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import javax.crypto.Mac;
 import javax.crypto.spec.SecretKeySpec;
 
 import com.azure.core.credential.AccessToken;
+import com.azure.core.credential.TokenCredential;
 import com.azure.core.credential.TokenRequestContext;
 import com.azure.identity.ManagedIdentityCredential;
 import com.azure.identity.ManagedIdentityCredentialBuilder;
@@ -46,6 +51,11 @@ class SQLServerSecurityUtility {
     // Environment variable for additionally allowed tenants. The tenantIds are comma delimited
     private static final String ADDITIONALLY_ALLOWED_TENANTS = "ADDITIONALLY_ALLOWED_TENANTS";
 
+    // Credential Cache for ManagedIdentityCredential and DefaultAzureCredential
+    private static final HashMap<String, Credential> CREDENTIAL_CACHE = new HashMap<>();
+
+    private static final Lock CREDENTIAL_LOCK = new ReentrantLock();
+
     private SQLServerSecurityUtility() {
         throw new UnsupportedOperationException(SQLServerException.getErrString("R_notSupported"));
     }
@@ -331,16 +341,35 @@ static void verifyColumnMasterKeyMetadata(SQLServerConnection connection, SQLSer
      */
     static SqlAuthenticationToken getManagedIdentityCredAuthToken(String resource,
             String managedIdentityClientId) throws SQLServerException {
-        ManagedIdentityCredential mic = null;
 
         if (logger.isLoggable(java.util.logging.Level.FINEST)) {
             logger.finest("Getting Managed Identity authentication token for: " + managedIdentityClientId);
         }
 
-        if (null != managedIdentityClientId && !managedIdentityClientId.isEmpty()) {
-            mic = new ManagedIdentityCredentialBuilder().clientId(managedIdentityClientId).build();
-        } else {
-            mic = new ManagedIdentityCredentialBuilder().build();
+        String key = getHashedSecret(
+                new String[] {managedIdentityClientId, ManagedIdentityCredential.class.getSimpleName()});
+        ManagedIdentityCredential mic = (ManagedIdentityCredential) getCredentialFromCache(key);
+
+        if (null == mic) {
+            CREDENTIAL_LOCK.lock();
+
+            try {
+                mic = (ManagedIdentityCredential) getCredentialFromCache(key);
+                if (null == mic) {
+                    ManagedIdentityCredentialBuilder micBuilder = new ManagedIdentityCredentialBuilder();
+
+                    if (null != managedIdentityClientId && !managedIdentityClientId.isEmpty()) {
+                        mic = micBuilder.clientId(managedIdentityClientId).build();
+                    } else {
+                        mic = micBuilder.build();
+                    }
+
+                    Credential credential = new Credential(mic);
+                    CREDENTIAL_CACHE.put(key, credential);
+                }
+            } finally {
+                CREDENTIAL_LOCK.unlock();
+            }
         }
 
         TokenRequestContext tokenRequestContext = new TokenRequestContext();
@@ -383,22 +412,49 @@ static SqlAuthenticationToken getDefaultAzureCredAuthToken(String resource,
         String intellijKeepassPath = System.getenv(INTELLIJ_KEEPASS_PASS);
         String[] additionallyAllowedTenants = getAdditonallyAllowedTenants();
 
-        DefaultAzureCredentialBuilder dacBuilder = new DefaultAzureCredentialBuilder();
-        DefaultAzureCredential dac = null;
+        int secretsLength = null == additionallyAllowedTenants ? 3 : additionallyAllowedTenants.length + 3;
+        String[] secrets = new String[secretsLength];
 
-        if (null != managedIdentityClientId && !managedIdentityClientId.isEmpty()) {
-            dacBuilder.managedIdentityClientId(managedIdentityClientId);
+        if (null != additionallyAllowedTenants && additionallyAllowedTenants.length != 0) {
+            System.arraycopy(additionallyAllowedTenants, 0, secrets, 3, additionallyAllowedTenants.length);
         }
 
-        if (null != intellijKeepassPath && !intellijKeepassPath.isEmpty()) {
-            dacBuilder.intelliJKeePassDatabasePath(intellijKeepassPath);
-        }
+        secrets[0] = DefaultAzureCredential.class.getSimpleName();
+        secrets[1] = managedIdentityClientId;
+        secrets[2] = intellijKeepassPath;
 
-        if (null != additionallyAllowedTenants && additionallyAllowedTenants.length != 0) {
-            dacBuilder.additionallyAllowedTenants(additionallyAllowedTenants);
-        }
+        String key = getHashedSecret(secrets);
+        DefaultAzureCredential dac = (DefaultAzureCredential) getCredentialFromCache(key);
+
+        if (null == dac) {
+            CREDENTIAL_LOCK.lock();
+
+            try {
+                dac = (DefaultAzureCredential) getCredentialFromCache(key);
+                if (null == dac) {
+                    DefaultAzureCredentialBuilder dacBuilder = new DefaultAzureCredentialBuilder();
+
+                    if (null != managedIdentityClientId && !managedIdentityClientId.isEmpty()) {
+                        dacBuilder.managedIdentityClientId(managedIdentityClientId);
+                    }
+
+                    if (null != intellijKeepassPath && !intellijKeepassPath.isEmpty()) {
+                        dacBuilder.intelliJKeePassDatabasePath(intellijKeepassPath);
+                    }
+
+                    if (null != additionallyAllowedTenants && additionallyAllowedTenants.length != 0) {
+                        dacBuilder.additionallyAllowedTenants(additionallyAllowedTenants);
+                    }
+
+                    dac = dacBuilder.build();
 
-        dac = dacBuilder.build();
+                    Credential credential = new Credential(dac);
+                    CREDENTIAL_CACHE.put(key, credential);
+                }
+            } finally {
+                CREDENTIAL_LOCK.unlock();
+            }
+        }
 
         TokenRequestContext tokenRequestContext = new TokenRequestContext();
         String scope = resource.endsWith(SQLServerMSAL4JUtils.SLASH_DEFAULT) ? resource : resource
@@ -430,4 +486,36 @@ private static String[] getAdditonallyAllowedTenants() {
 
         return null;
     }
+
+    private static TokenCredential getCredentialFromCache(String key) {
+        Credential credential = CREDENTIAL_CACHE.get(key);
+
+        if (null != credential) {
+            return credential.tokenCredential;
+        }
+
+        return null;
+    }
+
+    private static class Credential {
+        TokenCredential tokenCredential;
+
+        public Credential(TokenCredential tokenCredential) {
+            this.tokenCredential = tokenCredential;
+        }
+    }
+
+    private static String getHashedSecret(String[] secrets) throws SQLServerException {
+        try {
+            MessageDigest md = MessageDigest.getInstance("SHA-256");
+            for (String secret : secrets) {
+                if (null != secret) {
+                    md.update(secret.getBytes(java.nio.charset.StandardCharsets.UTF_16LE));
+                }
+            }
+            return new String(md.digest());
+        } catch (NoSuchAlgorithmException e) {
+            throw new SQLServerException(SQLServerException.getErrString("R_NoSHA256Algorithm"), e);
+        }
+    }
 }