feat: Param decorator to parse our app user agent strings (#16472)

Co-authored-by: kodiakhq[bot] <49736102+kodiakhq[bot]@users.noreply.github.com>

libs/nest/core/src/index.ts

@@ -1,3 +1,4 @@
 export * from './lib/decorators/nationalId.decorator'
+export * from './lib/decorators/ParsedUserAgent.decorator'
 export * from './lib/validators/isPersonNationalId.decorator'
 export * from './lib/validators/isNationalId.decorator'

libs/nest/core/src/lib/decorators/ParsedUserAgent.decorator.spec.ts

@@ -0,0 +1,78 @@
+import { parseUserAgent } from './ParsedUserAgent.decorator'
+
+describe('parseUserAgent Function', () => {
+  it('should parse new iOS app user agent', () => {
+    // Arrange
+    const userAgentString = 'IslandIsApp (1.0.0) Build/321 (ios/9.0.0)'
+
+    // Act
+    const result = parseUserAgent(userAgentString)
+
+    // Assert
+    expect(result).toEqual({
+      ua: userAgentString,
+      os: { name: 'iOS', version: '9.0.0' },
+      app: { name: 'IslandIsApp', version: '1.0.0', build: 321 },
+    })
+  })
+
+  it('should parse new Android app user agent', () => {
+    // Arrange
+    const userAgentString = 'IslandIsApp (2.1.0) Build/123 (android/11.0.0)'
+
+    // Act
+    const result = parseUserAgent(userAgentString)
+
+    // Assert
+    expect(result).toEqual({
+      ua: userAgentString,
+      os: { name: 'Android', version: '11.0.0' },
+      app: { name: 'IslandIsApp', version: '2.1.0', build: 123 },
+    })
+  })
+
+  it('should parse old iOS app user agent', () => {
+    // Arrange
+    const userAgentString = 'IslandApp/144 CFNetwork/1498.700.2 Darwin/23.6.0'
+
+    // Act
+    const result = parseUserAgent(userAgentString)
+
+    // Assert
+    expect(result).toEqual({
+      ua: userAgentString,
+      os: { name: 'iOS' },
+      app: { name: 'IslandIsApp' },
+    })
+  })
+
+  it('should parse old Android app user agent', () => {
+    // Arrange
+    const userAgentString = 'okhttp/4.9.2'
+
+    // Act
+    const result = parseUserAgent(userAgentString)
+
+    // Assert
+    expect(result).toEqual({
+      ua: userAgentString,
+      os: { name: 'Android' },
+      app: { name: 'IslandIsApp' },
+    })
+  })
+
+  it('should return empty app and os for unknown user agent', () => {
+    // Arrange
+    const userAgentString = 'UnknownUserAgent/1.0'
+
+    // Act
+    const result = parseUserAgent(userAgentString)
+
+    // Assert
+    expect(result).toEqual({
+      ua: userAgentString,
+      os: {},
+      app: {},
+    })
+  })
+})

libs/nest/core/src/lib/decorators/ParsedUserAgent.decorator.ts

@@ -0,0 +1,92 @@
+import { getRequest } from '@island.is/auth-nest-tools'
+import { createParamDecorator, ExecutionContext } from '@nestjs/common'
+
+// Old iOS app user agents:
+// - IslandApp/144 CFNetwork/1498.700.2 Darwin/23.6.0
+
+// Old Android app user agents. We associate it with IslandIsApp, assuming
+// there are no other React Native android apps calling our API.
+// - okhttp/4.9.2
+
+// New app user agents
+// - IslandIsApp (1.0.0}) Build/321 (ios/9.0.0)
+// - IslandIsApp (1.0.0}) Build/321 (android/9.0.0)
+
+export interface UserAgent {
+  ua: string
+  os: {
+    name?: 'iOS' | 'Android'
+    version?: string
+  }
+  app: {
+    name?: 'IslandIsApp'
+    version?: string
+    build?: number
+  }
+}
+
+/**
+ * Parses the user agent string and returns an object with the user agent, os and app information.
+ *
+ * Only supports parsing IslandIsApp user agents to start with but the interface is
+ * future compatible if we want to parse more user agents with ua-parser-js.
+ */
+export const parseUserAgent = (userAgentString: string): UserAgent => {
+  const userAgent: UserAgent = {
+    ua: userAgentString,
+    os: {},
+    app: {},
+  }
+
+  // Match new app user agents
+  const newAppRegex =
+    /IslandIsApp \(([^)]+)\) Build\/(\d+) \((ios|android)\/([^)]+)\)/
+  const newAppMatch = userAgentString.match(newAppRegex)
+
+  if (newAppMatch) {
+    userAgent.app.name = 'IslandIsApp'
+    userAgent.app.version = newAppMatch[1]
+    userAgent.app.build = parseInt(newAppMatch[2], 10)
+    userAgent.os.name = newAppMatch[3] === 'ios' ? 'iOS' : 'Android'
+    userAgent.os.version = newAppMatch[4]
+    return userAgent
+  }
+
+  // Match old iOS app user agents
+  const oldIosRegex = /IslandApp\/\d+ CFNetwork\/[^\s]+ Darwin\/[^\s]+/
+  const oldIosMatch = userAgentString.match(oldIosRegex)
+
+  if (oldIosMatch) {
+    userAgent.app.name = 'IslandIsApp'
+    userAgent.os.name = 'iOS'
+    return userAgent
+  }
+
+  // Match old Android app user agents
+  const oldAndroidRegex = /okhttp\/[^\s]+/
+  const oldAndroidMatch = userAgentString.match(oldAndroidRegex)
+
+  if (oldAndroidMatch) {
+    userAgent.app.name = 'IslandIsApp'
+    userAgent.os.name = 'Android'
+    return userAgent
+  }
+
+  // Default return, if no patterns matched
+  return userAgent
+}
+
+/**
+ * Decorator that parses the user agent string from the request headers and returns an object with the user agent, os
+ * and app information.
+ *
+ * Only supports parsing IslandIsApp user agents for now.
+ */
+export const ParsedUserAgent = createParamDecorator(
+  (_: unknown, context: ExecutionContext): UserAgent => {
+    const request = getRequest(context)
+    const userAgentString = request.headers['user-agent'] || ''
+
+    return parseUserAgent(userAgentString)
+  },
+)