fix: Optimize DNS resolution logic (#602)

Updates the instance DNS name regex to the correct permissive format.

See GoogleCloudPlatform/cloud-sql-go-connector#1143

Author: hessjcg

src/parse-instance-connection-name.ts

@@ -16,6 +16,9 @@ import {InstanceConnectionInfo} from './instance-connection-info';
 import {CloudSQLConnectorError} from './errors';
 import {resolveTxtRecord, resolveCnameRecord} from './dns-lookup';
 
+export const INSTANCE_DNS_NAME_PATTERN =
+  /^([a-zA-Z0-9]|[a-zA-Z0-9][a-zA-Z0-9-]{0,61}[a-zA-Z0-9])\.([a-zA-Z0-9]|[a-zA-Z0-9][a-zA-Z0-9-]{0,61}[a-zA-Z0-9])\.([a-zA-Z0-9]|[a-zA-Z0-9][a-zA-Z0-9-]{0,61}[a-zA-Z0-9])\.(sql|sql-psa|sql-psc)\.goog\.?$/;
+
 export interface DNSFetcher {
   resolveConnectSettings(region: string, dnsName: string): Promise<string>;
 }
@@ -27,13 +30,9 @@ export function parseInstanceDNSName(dnsName: string): {
   suffix: string;
   ok: boolean;
 } {
-  let name = dnsName.toLowerCase();
-  if (name.endsWith('.')) {
-    name = name.slice(0, -1);
-  }
-
-  const parts = name.split('.');
-  if (parts.length !== 5) {
+  const name = dnsName.toLowerCase();
+  const match = name.match(INSTANCE_DNS_NAME_PATTERN);
+  if (!match) {
     return {
       instanceLabel: '',
       projectLabel: '',
@@ -43,35 +42,10 @@ export function parseInstanceDNSName(dnsName: string): {
     };
   }
 
-  if (parts[4] !== 'goog') {
-    return {
-      instanceLabel: '',
-      projectLabel: '',
-      region: '',
-      suffix: '',
-      ok: false,
-    };
-  }
-
-  const suffixType = parts[3];
-  if (
-    suffixType !== 'sql' &&
-    suffixType !== 'sql-psa' &&
-    suffixType !== 'sql-psc'
-  ) {
-    return {
-      instanceLabel: '',
-      projectLabel: '',
-      region: '',
-      suffix: '',
-      ok: false,
-    };
-  }
-
-  const instanceLabel = parts[0];
-  const projectLabel = parts[1];
-  const region = parts[2];
-  const suffix = suffixType + '.goog';
+  const instanceLabel = match[1];
+  const projectLabel = match[2];
+  const region = match[3];
+  const suffix = match[4] + '.goog';
 
   if (region === 'global') {
     return {
@@ -83,37 +57,6 @@ export function parseInstanceDNSName(dnsName: string): {
     };
   }
 
-  if (instanceLabel.length !== 12) {
-    return {
-      instanceLabel: '',
-      projectLabel: '',
-      region: '',
-      suffix: '',
-      ok: false,
-    };
-  }
-
-  // Validate instanceLabel is hex
-  if (!/^[0-9a-f]{12}$/.test(instanceLabel)) {
-    return {
-      instanceLabel: '',
-      projectLabel: '',
-      region: '',
-      suffix: '',
-      ok: false,
-    };
-  }
-
-  if (!region.includes('-')) {
-    return {
-      instanceLabel: '',
-      projectLabel: '',
-      region: '',
-      suffix: '',
-      ok: false,
-    };
-  }
-
   return {instanceLabel, projectLabel, region, suffix, ok: true};
 }
 
@@ -178,14 +121,14 @@ export function isValidDomainName(name: string): boolean {
   return Boolean(matches);
 }
 
-const instanceDNSSuffixRegex = /\.sql(-\w+)?\.goog\.?$/;
-const globalInstanceDNSRegex = /\.global\.sql(-\w+)?\.goog\.?$/;
-
 export function isInstanceDNSName(name: string): boolean {
   const lower = name.toLowerCase();
-  return (
-    instanceDNSSuffixRegex.test(lower) && !globalInstanceDNSRegex.test(lower)
-  );
+  const match = lower.match(INSTANCE_DNS_NAME_PATTERN);
+  if (!match) {
+    return false;
+  }
+  const region = match[3];
+  return region !== 'global';
 }
 
 export function isInstanceConnectionName(name: string): boolean {

test/cloud-sql-instance-dns.ts

@@ -39,6 +39,9 @@ t.test('CloudSQLInstance DNS Lookup', async t => {
         expirationTime: '2033-01-06T10:00:00.232Z',
       };
     },
+    async resolveConnectSettings() {
+      return 'my-project:us-east1:my-instance';
+    },
   };
 
   let resolveARecordMock = async (): Promise<string[]> => {
@@ -161,4 +164,65 @@ t.test('CloudSQLInstance DNS Lookup', async t => {
 
     t.equal(instance.host, '127.0.0.1', 'Host should use metadata IP');
   });
+
+  t.test('optimization for immutable names - custom DNS', async t => {
+    resolveARecordMock = async () => ['10.0.0.1'];
+    resolveTXTRecordMock = async () => ['my-project:us-east1:my-instance'];
+
+    const instance = await CloudSQLInstance.getCloudSQLInstance({
+      ipType: IpAddressTypes.PUBLIC,
+      authType: AuthTypes.PASSWORD,
+      domainName: 'example.com',
+      sqlAdminFetcher: fetcher,
+    });
+    t.after(() => instance.close());
+
+    t.ok(
+      // eslint-disable-next-line @typescript-eslint/no-explicit-any
+      (instance as any).checkDomainID,
+      'should enable checkDomain interval for custom DNS'
+    );
+  });
+
+  t.test(
+    'optimization for immutable names - immutable instance DNS',
+    async t => {
+      resolveARecordMock = async () => ['10.0.0.1'];
+
+      const instance = await CloudSQLInstance.getCloudSQLInstance({
+        ipType: IpAddressTypes.PUBLIC,
+        authType: AuthTypes.PASSWORD,
+        domainName: '0123456789ab.fedcba9876543.us-central1.sql-psc.goog',
+        sqlAdminFetcher: fetcher,
+      });
+      t.after(() => instance.close());
+
+      t.notOk(
+        // eslint-disable-next-line @typescript-eslint/no-explicit-any
+        (instance as any).checkDomainID,
+        'should NOT enable checkDomain interval for immutable instance DNS'
+      );
+    }
+  );
+
+  t.test(
+    'optimization for immutable names - mutable global instance DNS',
+    async t => {
+      resolveARecordMock = async () => ['10.0.0.1'];
+
+      const instance = await CloudSQLInstance.getCloudSQLInstance({
+        ipType: IpAddressTypes.PUBLIC,
+        authType: AuthTypes.PASSWORD,
+        domainName: '0123456789ab.fedcba9876543.global.sql-psc.goog',
+        sqlAdminFetcher: fetcher,
+      });
+      t.after(() => instance.close());
+
+      t.ok(
+        // eslint-disable-next-line @typescript-eslint/no-explicit-any
+        (instance as any).checkDomainID,
+        'should enable checkDomain interval for mutable global instance DNS'
+      );
+    }
+  );
 });

test/parse-instance-connection-name.ts

@@ -406,6 +406,26 @@ t.test('parseInstanceDNSName', async t => {
         ok: true,
       },
     },
+    {
+      dns: 'not-hex-label.fedcba9876543.us-central1.sql-psc.goog',
+      want: {
+        instanceLabel: 'not-hex-label',
+        projectLabel: 'fedcba9876543',
+        region: 'us-central1',
+        suffix: 'sql-psc.goog',
+        ok: true,
+      },
+    },
+    {
+      dns: 'abc.def.uscentral.sql-psc.goog',
+      want: {
+        instanceLabel: 'abc',
+        projectLabel: 'def',
+        region: 'uscentral',
+        suffix: 'sql-psc.goog',
+        ok: true,
+      },
+    },
     {
       dns: '0123456789ab.fedcba9876543.global.sql-psc.goog',
       want: {
@@ -417,7 +437,7 @@ t.test('parseInstanceDNSName', async t => {
       },
     },
     {
-      dns: 'not-hex-label.fedcba9876543.us-central1.sql-psc.goog',
+      dns: '0123456789ab.fedcba9876543.us-central1.invalid-suffix.goog',
       want: {
         instanceLabel: '',
         projectLabel: '',
@@ -427,7 +447,27 @@ t.test('parseInstanceDNSName', async t => {
       },
     },
     {
-      dns: '0123456789ab.fedcba9876543.us-central1.invalid-suffix.goog',
+      dns: '-starts-with-hyphen.proj.region.sql.goog',
+      want: {
+        instanceLabel: '',
+        projectLabel: '',
+        region: '',
+        suffix: '',
+        ok: false,
+      },
+    },
+    {
+      dns: 'ends-with-hyphen-.proj.region.sql.goog',
+      want: {
+        instanceLabel: '',
+        projectLabel: '',
+        region: '',
+        suffix: '',
+        ok: false,
+      },
+    },
+    {
+      dns: 'empty..region.sql.goog',
       want: {
         instanceLabel: '',
         projectLabel: '',