Add SASL OAUTHBEARER support with application-supplied tokens

docs/pages/apis/client.mdx

@@ -12,6 +12,7 @@ Every field of the `config` object is entirely optional. A `Client` instance wil
 type Config = {
   user?: string, // default process.env.PGUSER || process.env.USER
   password?: string or function, //default process.env.PGPASSWORD
+  oauthBearerToken?: string or function, // bearer token or callback returning a bearer token for OAUTHBEARER authentication
   host?: string, // default process.env.PGHOST
   port?: number, // default process.env.PGPORT
   database?: string, // default process.env.PGDATABASE || user

docs/pages/features/connecting.mdx

@@ -114,6 +114,26 @@ const pool = new Pool({
 })
 ```
 
+PostgreSQL servers configured for OAuth can authenticate with a bearer token using the SASL `OAUTHBEARER` mechanism.
+Pass the token directly, or provide a synchronous or asynchronous callback that resolves to a token string.
+When `oauthBearerToken` is set, `OAUTHBEARER` takes precedence over `SCRAM-SHA-256-PLUS` even when TLS channel binding is available.
+`pg` does not perform the OAuth authorization flow; your application is responsible for fetching and caching tokens from your OAuth provider.
+Using a callback is recommended for short-lived tokens, as it is invoked for each new connection with the connection parameters and must return a non-empty token string.
+
+```js
+import pg from 'pg'
+const { Pool } = pg
+
+const pool = new Pool({
+  user: 'api-user',
+  host: 'database.server.com',
+  database: 'my-db',
+  oauthBearerToken: async () => {
+    return getAccessToken()
+  },
+})
+```
+
 ### Unix Domain Sockets
 
 Connections to unix sockets can also be made. This can be useful on distros like Ubuntu, where authentication is managed via the socket connection instead of a password.

packages/pg-pool/index.js

@@ -78,6 +78,16 @@ class Pool extends EventEmitter {
         value: options.password,
       })
     }
+    if (options != null && 'oauthBearerToken' in options) {
+      // "hiding" the OAuth bearer token so it doesn't show up in stack traces
+      // or if the pool is console.logged
+      Object.defineProperty(this.options, 'oauthBearerToken', {
+        configurable: true,
+        enumerable: false,
+        writable: true,
+        value: options.oauthBearerToken,
+      })
+    }
     if (options != null && options.ssl && options.ssl.key) {
       // "hiding" the ssl->key so it doesn't show up in stack traces
       // or if the client is console.logged

packages/pg-protocol/src/outbound-serializer.test.ts

@@ -45,6 +45,11 @@ describe('serializer', () => {
     assert.deepEqual(actual, new BufferList().addString('data').join(true, 'p'))
   })
 
+  it('builds SASLResponseMessage message', function () {
+    const actual = serialize.sendSASLResponseMessage('data')
+    assert.deepEqual(actual, new BufferList().addString('data').join(true, 'p'))
+  })
+
   it('builds query message', function () {
     const txt = 'select * from boom'
     const actual = serialize.query(txt)

packages/pg-protocol/src/serializer.ts

@@ -53,10 +53,12 @@ const sendSASLInitialResponseMessage = function (mechanism: string, initialRespo
   return writer.flush(code.startup)
 }
 
-const sendSCRAMClientFinalMessage = function (additionalData: string): Buffer {
+const sendSASLResponseMessage = function (additionalData: string): Buffer {
   return writer.addString(additionalData).flush(code.startup)
 }
 
+const sendSCRAMClientFinalMessage = sendSASLResponseMessage
+
 const query = (text: string): Buffer => {
   return writer.addCString(text).flush(code.query)
 }
@@ -261,6 +263,7 @@ const serialize = {
   password,
   requestSsl,
   sendSASLInitialResponseMessage,
+  sendSASLResponseMessage,
   sendSCRAMClientFinalMessage,
   query,
   parse,

packages/pg/lib/client.js

@@ -65,6 +65,12 @@ class Client extends EventEmitter {
       writable: true,
       value: this.connectionParameters.password,
     })
+    Object.defineProperty(this, 'oauthBearerToken', {
+      configurable: true,
+      enumerable: false,
+      writable: true,
+      value: this.connectionParameters.oauthBearerToken,
+    })
 
     this.replication = this.connectionParameters.replication
 
@@ -305,6 +311,33 @@ class Client extends EventEmitter {
     }
   }
 
+  _getOAuthBearerToken(cb) {
+    const con = this.connection
+    if (typeof this.oauthBearerToken === 'function') {
+      let tokenResult
+      try {
+        tokenResult = this.oauthBearerToken(this.connectionParameters)
+      } catch (err) {
+        process.nextTick(() => con.emit('error', err))
+        return
+      }
+      this._Promise.resolve(tokenResult).then(
+        (token) => {
+          if (typeof token !== 'string') {
+            con.emit('error', new TypeError('OAuth bearer token must be a string'))
+            return
+          }
+          cb(token)
+        },
+        (err) => {
+          con.emit('error', err)
+        }
+      )
+    } else {
+      cb(this.oauthBearerToken)
+    }
+  }
+
   _handleAuthCleartextPassword(msg) {
     this._getPassword(() => {
       this.connection.password(this.password)
@@ -323,18 +356,35 @@ class Client extends EventEmitter {
   }
 
   _handleAuthSASL(msg) {
-    this._getPassword(() => {
+    const hasOAuth = msg.mechanisms.includes('OAUTHBEARER')
+    const hasScram = msg.mechanisms.includes('SCRAM-SHA-256') || msg.mechanisms.includes('SCRAM-SHA-256-PLUS')
+
+    const beginSASLSession = (oauthBearerToken) => {
       try {
-        this.saslSession = sasl.startSession(
-          msg.mechanisms,
-          this.enableChannelBinding && this.connection.stream,
-          this.scramMaxIterations
-        )
+        this.saslSession = sasl.startSession(msg.mechanisms, this.enableChannelBinding && this.connection.stream, {
+          oauthBearerToken,
+          scramMaxIterations: this.scramMaxIterations,
+        })
         this.connection.sendSASLInitialResponseMessage(this.saslSession.mechanism, this.saslSession.response)
       } catch (err) {
         this.connection.emit('error', err)
       }
-    })
+    }
+
+    if (hasOAuth && this.oauthBearerToken != null) {
+      return this._getOAuthBearerToken((oauthBearerToken) => {
+        beginSASLSession(oauthBearerToken)
+      })
+    }
+
+    if (hasScram) {
+      return this._getPassword(() => {
+        beginSASLSession()
+      })
+    }
+
+    // Let sasl.startSession throw the unsupported-mechanism error.
+    beginSASLSession()
   }
 
   async _handleAuthSASLContinue(msg) {
@@ -345,7 +395,14 @@ class Client extends EventEmitter {
         msg.data,
         this.enableChannelBinding && this.connection.stream
       )
-      this.connection.sendSCRAMClientFinalMessage(this.saslSession.response)
+      this.connection.sendSASLResponseMessage(this.saslSession.response)
+      if (this.saslSession.oauthError) {
+        this.connection.emit(
+          'error',
+          new Error('SASL: OAUTHBEARER authentication failed: ' + this.saslSession.oauthError)
+        )
+        return
+      }
     } catch (err) {
       this.connection.emit('error', err)
     }

packages/pg/lib/connection-parameters.js

@@ -79,6 +79,16 @@ class ConnectionParameters {
       value: val('password', config),
     })
 
+    // oauthBearerToken is intentionally not read from environment variables.
+    // OAuth bearer tokens are short-lived credentials obtained programmatically;
+    // they should not be stored in env vars the way a static password would be.
+    Object.defineProperty(this, 'oauthBearerToken', {
+      configurable: true,
+      enumerable: false,
+      writable: true,
+      value: config.oauthBearerToken,
+    })
+
     this.binary = val('binary', config)
     this.options = val('options', config)
 

packages/pg/lib/connection.js

@@ -157,8 +157,12 @@ class Connection extends EventEmitter {
     this._send(serialize.sendSASLInitialResponseMessage(mechanism, initialResponse))
   }
 
+  sendSASLResponseMessage(additionalData) {
+    this._send(serialize.sendSASLResponseMessage(additionalData))
+  }
+
   sendSCRAMClientFinalMessage(additionalData) {
-    this._send(serialize.sendSCRAMClientFinalMessage(additionalData))
+    this.sendSASLResponseMessage(additionalData)
   }
 
   _send(buffer) {

packages/pg/lib/crypto/sasl.js

@@ -32,16 +32,48 @@ function saslprep(password) {
 
 const DEFAULT_MAX_SCRAM_ITERATIONS = 100000
 
-function startSession(mechanisms, stream, scramMaxIterations = DEFAULT_MAX_SCRAM_ITERATIONS) {
-  const candidates = ['SCRAM-SHA-256']
-  if (stream) candidates.unshift('SCRAM-SHA-256-PLUS') // higher-priority, so placed first
+function startSession(mechanisms, stream, options) {
+  const candidates = []
+  const isOptionsObject = options !== null && typeof options === 'object'
+  const oauthBearerToken = isOptionsObject ? options.oauthBearerToken : undefined
+  const scramMaxIterations =
+    typeof options === 'number'
+      ? options
+      : isOptionsObject && 'scramMaxIterations' in options
+      ? options.scramMaxIterations
+      : DEFAULT_MAX_SCRAM_ITERATIONS
+
+  if (oauthBearerToken !== undefined && oauthBearerToken !== null) {
+    // OAUTHBEARER is preferred when a token is explicitly provided, even over SCRAM-SHA-256-PLUS.
+    candidates.push('OAUTHBEARER')
+  }
+
+  if (stream) candidates.push('SCRAM-SHA-256-PLUS')
+  candidates.push('SCRAM-SHA-256')
 
   const mechanism = candidates.find((candidate) => mechanisms.includes(candidate))
 
   if (!mechanism) {
+    if (mechanisms.includes('OAUTHBEARER')) {
+      throw new Error('SASL: OAUTHBEARER requires an oauthBearerToken')
+    }
     throw new Error('SASL: Only mechanism(s) ' + candidates.join(' and ') + ' are supported')
   }
 
+  if (mechanism === 'OAUTHBEARER') {
+    if (typeof oauthBearerToken !== 'string') {
+      throw new Error('SASL: OAUTHBEARER token must be a string')
+    }
+    if (oauthBearerToken === '') {
+      throw new Error('SASL: OAUTHBEARER token must be a non-empty string')
+    }
+    return {
+      mechanism,
+      response: 'n,,\x01auth=Bearer ' + oauthBearerToken + '\x01\x01',
+      message: 'SASLInitialResponse',
+    }
+  }
+
   if (mechanism === 'SCRAM-SHA-256-PLUS' && typeof stream.getPeerCertificate !== 'function') {
     // this should never happen if we are really talking to a Postgres server
     throw new Error('SASL: Mechanism SCRAM-SHA-256-PLUS requires a certificate')
@@ -63,6 +95,21 @@ async function continueSession(session, password, serverData, stream) {
   if (session.message !== 'SASLInitialResponse') {
     throw new Error('SASL: Last message was not SASLInitialResponse')
   }
+  if (session.mechanism === 'OAUTHBEARER') {
+    if (typeof serverData !== 'string') {
+      throw new Error('SASL: OAUTHBEARER serverData must be a string')
+    }
+    // PostgreSQL sends a JSON challenge when OAUTHBEARER authentication fails.
+    // The client must still send the RFC 7628 dummy response ("\x01") before the
+    // server can finish the failed authentication exchange, so record the payload
+    // for the caller to surface after it sends session.response.
+    if (serverData.length > 0) {
+      session.oauthError = serverData
+    }
+    session.message = 'SASLResponse'
+    session.response = '\x01'
+    return
+  }
   if (typeof password !== 'string') {
     throw new Error('SASL: SCRAM-SERVER-FIRST-MESSAGE: client password must be a string')
   }
@@ -127,6 +174,12 @@ async function continueSession(session, password, serverData, stream) {
 }
 
 function finalizeSession(session, serverData) {
+  if (session.mechanism === 'OAUTHBEARER') {
+    // OAUTHBEARER auth ends after continueSession (client sends \x01, server replies with
+    // AuthenticationOk). AuthenticationSASLFinal is never sent for this mechanism, so
+    // reaching here means a misbehaving server or a protocol bug.
+    throw new Error('SASL: OAUTHBEARER does not support server final messages')
+  }
   if (session.message !== 'SASLResponse') {
     throw new Error('SASL: Last message was not SASLResponse')
   }

packages/pg/test/unit/client/credential-redaction-tests.js

@@ -0,0 +1,33 @@
+'use strict'
+const helper = require('./test-helper')
+const assert = require('assert')
+const util = require('util')
+
+const suite = new helper.Suite()
+const test = suite.test.bind(suite)
+
+const oauthBearerToken = 'FAIL THIS OAUTH BEARER TOKEN TEST'
+
+test('credential redaction', function () {
+  test('OAuth bearer token should not exist in toString() output', () => {
+    const pool = new helper.pg.Pool({ oauthBearerToken })
+    const client = new helper.pg.Client({ oauthBearerToken })
+    assert(pool.toString().indexOf(oauthBearerToken) === -1)
+    assert(client.toString().indexOf(oauthBearerToken) === -1)
+  })
+
+  test('OAuth bearer token should not exist in util.inspect output', () => {
+    const pool = new helper.pg.Pool({ oauthBearerToken })
+    const client = new helper.pg.Client({ oauthBearerToken })
+    const depth = 20
+    assert(util.inspect(pool, { depth }).indexOf(oauthBearerToken) === -1)
+    assert(util.inspect(client, { depth }).indexOf(oauthBearerToken) === -1)
+  })
+
+  test('OAuth bearer token should not exist in json.stringify output', () => {
+    const pool = new helper.pg.Pool({ oauthBearerToken })
+    const client = new helper.pg.Client({ oauthBearerToken })
+    assert(JSON.stringify(pool).indexOf(oauthBearerToken) === -1)
+    assert(JSON.stringify(client).indexOf(oauthBearerToken) === -1)
+  })
+})