fix(auth): harden OIDC web callback URL validation

test/server/auth/OidcAuthStrategy.test.js

@@ -0,0 +1,75 @@
+const { expect } = require('chai')
+const sinon = require('sinon')
+
+const OidcAuthStrategy = require('../../../server/auth/OidcAuthStrategy')
+const Logger = require('../../../server/Logger')
+
+describe('OidcAuthStrategy - isValidWebCallbackUrl', () => {
+  /** @type {OidcAuthStrategy} */
+  let strategy
+
+  beforeEach(() => {
+    global.RouterBasePath = ''
+    strategy = new OidcAuthStrategy()
+    sinon.stub(Logger, 'warn')
+    sinon.stub(Logger, 'error')
+  })
+
+  afterEach(() => {
+    sinon.restore()
+  })
+
+  function mockReq({ secure = false, host = 'books.example.com', xForwardedProto = null } = {}) {
+    return {
+      secure,
+      get(header) {
+        if (header === 'host') return host
+        if (header === 'x-forwarded-proto') return xForwardedProto
+        return null
+      }
+    }
+  }
+
+  it('accepts a same-origin relative path when router base path is empty', () => {
+    expect(strategy.isValidWebCallbackUrl('/library', mockReq())).to.equal(true)
+  })
+
+  it('accepts a same-origin absolute https URL', () => {
+    const req = mockReq({ secure: true })
+    expect(strategy.isValidWebCallbackUrl('https://books.example.com/library', req)).to.equal(true)
+  })
+
+  it('rejects protocol-relative URLs', () => {
+    expect(strategy.isValidWebCallbackUrl('//evil.example/capture', mockReq())).to.equal(false)
+  })
+
+  it('rejects backslash-prefixed URLs', () => {
+    expect(strategy.isValidWebCallbackUrl('/\\evil.example/capture', mockReq())).to.equal(false)
+  })
+
+  it('rejects absolute external URLs', () => {
+    expect(strategy.isValidWebCallbackUrl('http://evil.example/capture', mockReq())).to.equal(false)
+  })
+
+  it('rejects encoded protocol-relative path segments', () => {
+    expect(strategy.isValidWebCallbackUrl('/%2F%2Fevil.example/capture', mockReq())).to.equal(false)
+  })
+
+  it('rejects same-origin URLs outside router base path', () => {
+    global.RouterBasePath = '/audiobookshelf'
+    expect(strategy.isValidWebCallbackUrl('/login', mockReq())).to.equal(false)
+    expect(strategy.isValidWebCallbackUrl('/audiobookshelf/login', mockReq())).to.equal(true)
+  })
+
+  it('rejects empty and malformed callback URLs', () => {
+    expect(strategy.isValidWebCallbackUrl('', mockReq())).to.equal(false)
+    expect(strategy.isValidWebCallbackUrl(null, mockReq())).to.equal(false)
+    expect(strategy.isValidWebCallbackUrl('not a url', mockReq())).to.equal(false)
+  })
+
+  it('uses x-forwarded-proto when determining same-origin https URLs', () => {
+    const req = mockReq({ xForwardedProto: 'https' })
+    expect(strategy.isValidWebCallbackUrl('https://books.example.com/login', req)).to.equal(true)
+    expect(strategy.isValidWebCallbackUrl('http://books.example.com/login', req)).to.equal(false)
+  })
+})