SourZap

Rootless Deep Packet Inspection (DPI) Circumvention, DNS-over-HTTPS & Network Monitor for Android, built with Material 3 Expressive.

SourZap is an advanced Android utility engineered to bypass Deep Packet Inspection (DPI) censorship, streaming throttling, and network filtering on mobile (LTE/5G) and Wi-Fi networks. It brings packet desynchronization techniques inspired by Zapret and ByeDPI directly to non-rooted Android devices through a local VpnService interface.

Many telecom providers and middleboxes inspect initial TLS ClientHello packets to identify destination Server Name Indications (SNI) or HTTP Host headers, throttling video streams (YouTube 4K/1080p, Twitch, Instagram Reels) or blocking services like Discord voice RTC gateways. SourZap intercepts and fragments these initial handshake frames in user-space, preventing middlebox detection while allowing remote servers to reassemble the stream normally.

How It Works [ App Traffic ] ──> [ Local TUN Interface (10.0.0.2 / fd00::1) ] ──> [ SourZap Core Engine ] │ ┌───────────────────────────────────────────────────────────────────────────┴───────────────────────────────────────────────────────────────────────────┐ │ │ │ ▼ ▼ ▼ [ 0ms LRU DNS Cache + Multi-DoH ] [ Automated Handshake Desync ] [ Steady-State Data Pump ] Thread-safe LRU Cache + Singleflight Applies TLS Split2, HTTP Host Casing, Zero-allocation 4-tier buffer pool Coalesced lookup across Cloudflare / Google / Quad9 TCP FIN/RST state synthesis, and ICMP QUIC reject 8x UDP relay sockets for BitTorrent swarms Local VPN Tunnel: Directs device traffic through an internal virtual network interface (10.0.0.2/24). No external VPN server is required—all processing occurs locally on the device with zero latency overhead. Universal Automated DPI Evasion: Zero-configuration engine tuned automatically: TLS Record Header Split2: Splits the ClientHello into two TCP segments right at the SNI boundary (TCP_NODELAY), evading shallow DPI inspection. HTTP Host Desynchronization: Modifies HTTP Host header casing (hOst: ) to fool legacy HTTP filters. Instant QUIC ICMP Rejection: Synthesizes immediate ICMP Port Unreachable packets for UDP 443 QUIC attempts, accelerating fallback to unthrottled TCP in 0ms. IPv6 ICMPv6 Leak Prevention: Synthesizes RFC 4443 ICMPv6 Destination Unreachable packets, triggering instant Happy Eyeballs fallback to IPv4 with zero DNS leaks. High-Throughput Layer-3 P2P BitTorrent Engine: Zero-allocation direct packet slicing in TunTcpRelay and TunUdpRelay. 8-socket protected DatagramSocket pool with 2MB kernel buffers for simultaneous DHT peers and multi-tracker announces (udp://...:1337, 6969). Native BitTorrent handshake detection (\x13BitTorrent protocol) with raw passthrough. Dynamic Network Handover: Seamless Wi-Fi ↔ 5G roaming via ConnectivityManager.NetworkCallback with setUnderlyingNetworks to prevent connection drops. Features Rootless & Standalone: Operates entirely in user-space without root, Magisk, or Termux. Material You Expressive UI: Organic sinusoidal wavy progress lines, dynamic Monet palette extraction, edge-to-edge window insets, and 100% SVG vector iconography (zero emojis). Comprehensive Speed Test: Multi-stream broadband diagnostic benchmark measuring Ping, Jitter, Download Speed, Upload Speed, and Connection Stability with a dynamic Monet gradient speedometer gauge. Enhanced Traffic Inspector: Real-time throughput meters, animated protocol filter tabs (All Flows, HTTPS/TLS, DNS, BitTorrent, UDP), search/filtering, and diagnostic export. 0ms DNS-over-HTTPS (DoH): Thread-safe in-memory LRU DNS cache with 5-minute TTL, singleflight deduplication, and multi-bootstrap failover (Cloudflare, Google, Quad9, AdGuard). In-App Direct Updater: Automatic GitHub release updater with static CDN IP fallback to prevent ISP DNS blocking during updates.