waf-platform/EdgeHttpDNS/sdk/ios/CLAUDE.md

CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

Build & Test Commands

# Install dependencies
pod install

# Build SDK (Release configuration)
xcodebuild -workspace AlicloudHttpDNS.xcworkspace -scheme AlicloudHttpDNS -configuration Release build

# Run all unit tests
xcodebuild test -workspace AlicloudHttpDNS.xcworkspace -scheme AlicloudHttpDNSTests -destination 'platform=iOS Simulator,name=iPhone 15'

# Build distributable XCFramework
sh build_xc_framework.sh

Note: After creating new Xcode files, wait for the user to add them to the appropriate target before running builds or tests.

Architecture Overview

This is an iOS HTTPDNS SDK with a multi-layered architecture designed for secure, cached, and resilient DNS resolution over HTTP/HTTPS.

Core Architecture Layers

1. Public API Layer (HttpdnsService)

• Singleton facade providing three resolution modes:
  • resolveHostSync: - Blocking with timeout
  • resolveHostAsync: - Non-blocking with callbacks
  • resolveHostSyncNonBlocking: - Returns cache immediately, refreshes async
• Manages multi-account instances (one per account ID)
• Configuration entry point for all SDK features

2. Request Management Layer (HttpdnsRequestManager)

• Orchestrates cache lookups before triggering network requests
• Manages two-tier caching:
  • Memory cache (HttpdnsHostObjectInMemoryCache)
  • Persistent SQLite cache (HttpdnsDB)
• Handles TTL validation and expired IP reuse policy
• Coordinates retry logic and degradation to local DNS

3. Network Transport Layer (HttpdnsNWHTTPClient)

• Low-level HTTP/HTTPS transport using Apple's Network framework
• Singleton with persistent connection pooling (max 4 idle connections per host:port:scheme)
• Manages reusable connections (HttpdnsNWReusableConnection) with automatic idle timeout (30s)
• Thread-safe concurrent request handling via serial pool queue
• Custom HTTP header parser supporting chunked transfer encoding
• TLS certificate validation with configurable trust evaluation
• Exposed by HttpdnsRemoteResolver for DNS resolution requests

4. DNS Resolution Layer

• HttpdnsRemoteResolver: HTTPS/HTTP requests to Alicloud servers
  • Builds authenticated requests with HMAC-SHA256 signatures
  • Optional AES-CBC encryption for sensitive parameters
  • Parses JSON responses into HttpdnsHostObject (IPv4/IPv6)
  • Uses HttpdnsNWHTTPClient for actual HTTP transport
• HttpdnsLocalResolver: Fallback to system DNS when remote fails

5. Scheduling & Service Discovery (HttpdnsScheduleCenter)

• Maintains regional service endpoint pools (CN, HK, SG, US, DE)
• Rotates between endpoints on failure for load balancing
• Separates IPv4 and IPv6 endpoint lists
• Per-account endpoint isolation

6. Data Flow (Synchronous Resolution)

User Request
  → Validate & wrap in HttpdnsRequest
  → Check memory cache (valid? return)
  → Load from SQLite DB (valid? return)
  → HttpdnsRemoteResolver
      - Build URL with auth (HMAC-SHA256)
      - Encrypt params if enabled (AES-CBC)
      - Send to service endpoint
      - Parse JSON response
      - Decrypt if needed
  → Cache in memory + DB
  → Return HttpdnsResult

On Failure:
  → Retry with different endpoint (max 1 retry)
  → Return expired IP (if setReuseExpiredIPEnabled:YES)
  → Fall back to local DNS (if setDegradeToLocalDNSEnabled:YES)
  → Return nil

Authentication & Encryption

Request Signing:

• All sensitive params signed with HMAC-SHA256
• Signature includes: account ID, expiration timestamp, domain, query type
• Params sorted alphabetically before signing
• Expiration: current_time + 10 minutes

Request Encryption (Optional):

• Domain name, query type, and SDNS params encrypted with AES-CBC
• Encrypted blob included as enc parameter
• Only encrypted when aesSecretKey provided at init

Key Internal Components

• HttpdnsHostObject: Internal model with separate IPv4/IPv6 arrays, TTLs, timestamps
• HttpdnsResult: Public-facing result model (simplified view)
• HttpdnsHostRecord: Serializable model for SQLite persistence
• HttpdnsNWHTTPClient: Singleton HTTP transport layer with connection pooling
• HttpdnsNWReusableConnection: Wrapper for Network framework connections with idle timeout tracking
• HttpdnsIpStackDetector: Detects network stack type (IPv4/IPv6 capability)
• HttpdnsReachability: Monitors network changes, triggers pre-resolution
• HttpdnsUtil: Crypto utilities (HMAC, AES), IP validation, encoding

Concurrency Model

• Concurrent queues for async user requests and DNS resolution
• Serial pool queue in HttpdnsNWHTTPClient for connection pool management
• dispatch_semaphore_t for blocking synchronous calls
• HttpDnsLocker prevents duplicate concurrent resolution of same domain
• Network framework handles underlying I/O asynchronously

Coding Conventions

Style:

• 4-space indentation, no trailing whitespace
• Braces on same line as control statements; body starts on next line
• Always use braces for control statement bodies, even single statements
• Comments in Chinese, only for complex logic explaining WHY

Naming:

• Types/files: UpperCamelCase (e.g., AlicloudHttpDNSClient.h)
• Methods/variables: lowerCamelCase
• Constants: kAC... prefix
• Internal headers: +Internal.h suffix

Commit Messages:

• Use conventional prefixes: feat:, fix:, docs:, refactor:, chore:, config:
• Write in Chinese
• After git add, run: /Users/xuyecan/.macconfig/script/strip-trailing-ws-in-diff --staged

Testing Notes

• Test target: AlicloudHttpDNSTests
• OCMock-based tests may have memory issues when run in batch - run individually if needed
• Non-mock tests use predefined credentials:
  • Account ID: 1000000
  • Test domains: *.onlyforhttpdnstest.run.place (renewed annually)
• Never commit real production Account IDs or Secret Keys
• Test file naming mirrors class under test (e.g., AlicloudHttpDNSClientTests.m)
• Network layer integration tests organized into 5 focused modules:
  • HttpdnsNWHTTPClient_BasicIntegrationTests.m: Basic HTTP/HTTPS requests
  • HttpdnsNWHTTPClient_ConcurrencyTests.m: Thread safety and concurrent access
  • HttpdnsNWHTTPClient_PoolManagementTests.m: Connection pooling and reuse
  • HttpdnsNWHTTPClient_EdgeCasesAndTimeoutTests.m: Timeout and error handling
  • HttpdnsNWHTTPClient_StateMachineTests.m: Connection lifecycle state transitions

SDK-Specific Notes

Multi-Account Support:

• Each account ID gets isolated singleton instance
• Separate endpoint pools, caches, and configurations per account

Public vs Internal Headers:

• Public headers listed in AlicloudHTTPDNS.podspec under public_header_files
• Internal headers use +Internal.h suffix and are not exposed
• Umbrella header: AlicloudHttpDNS.h imports all public APIs

Required System Frameworks:

• CoreTelephony, SystemConfiguration, Network (for HTTP transport)
• Libraries: sqlite3.0, resolv, z
• Linker flags: -ObjC -lz
• Minimum deployment target: iOS 12.0+ (required for Network framework)

Pre-Resolution Strategy:

• Call setPreResolveHosts:byIPType: at app startup for hot domains
• Automatically re-triggered on network changes (WiFi ↔ cellular)
• Batch requests combine multiple hosts in single HTTP call

Persistence & Cache:

• SQLite DB per account in isolated directory
• Enable with setPersistentCacheIPEnabled:YES
• Automatic expiration cleanup
• Speeds up cold starts with pre-cached DNS results