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//! NAT traversal functionality for ZK Protocol
//!
//! Provides hole punching, UPnP, NAT-PMP, and other NAT traversal techniques.
use std::net::{IpAddr, SocketAddr};
use std::time::Duration;
use tokio::time::timeout;
use tracing::{debug, info, warn};
use crate::{WireError, Result};
/// Represents different types of NAT configurations
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum NatType {
/// No NAT, directly accessible
None,
/// Full cone NAT
FullCone,
/// Restricted cone NAT
RestrictedCone,
/// Port restricted cone NAT
PortRestrictedCone,
/// Symmetric NAT (hardest to traverse)
Symmetric,
/// Unknown NAT type
Unknown,
}
/// NAT traversal handler
pub struct NatTraversal {
/// Local address
local_addr: SocketAddr,
/// Discovered NAT type
nat_type: NatType,
/// UPnP enabled
upnp_enabled: bool,
/// NAT-PMP enabled
nat_pmp_enabled: bool,
}
impl NatTraversal {
/// Create a new NAT traversal handler
pub fn new() -> Self {
Self {
local_addr: "0.0.0.0:0".parse().unwrap(),
nat_type: NatType::Unknown,
upnp_enabled: false,
nat_pmp_enabled: false,
}
}
/// Set the local address for NAT traversal
pub fn with_local_addr(mut self, addr: SocketAddr) -> Self {
self.local_addr = addr;
self
}
/// Discover the NAT type by testing connectivity with multiple STUN servers
pub async fn discover_nat_type(&mut self) -> Result<NatType> {
info!("Discovering NAT type for {}", self.local_addr);
// Test 1: Basic connectivity with first STUN server
let addr1 = self.test_stun_server("stun.l.google.com:19302").await?;
// Test 2: Different server to check for consistent mapping
let addr2 = self.test_stun_server("stun1.l.google.com:19302").await?;
// Test 3: Different port on same server to check port mapping behavior
let addr3 = self.test_stun_server("stun.l.google.com:3478").await?;
self.nat_type = if addr1.ip() != addr2.ip() {
NatType::Symmetric // Different IPs = symmetric NAT
} else if addr1.port() != addr3.port() {
NatType::PortRestrictedCone // Different ports = port restricted
} else {
NatType::FullCone // Same IP and port = full cone
};
debug!("Detected NAT type: {:?}", self.nat_type);
Ok(self.nat_type)
}
/// Test connectivity with a STUN server and return the discovered address
async fn test_stun_server(&self, server_addr: &str) -> Result<SocketAddr> {
use crate::stun::StunClient;
let mut client = StunClient::new(server_addr).await;
client.discover().await
}
/// Enable UPnP port mapping
pub async fn enable_upnp(&mut self) -> Result<()> {
info!("Attempting to enable UPnP");
// Simplified UPnP implementation
// In reality, this would involve SSDP discovery and SOAP requests
match self.discover_upnp_gateway().await {
Ok(gateway) => {
info!("Found UPnP gateway: {}", gateway);
self.upnp_enabled = true;
Ok(())
}
Err(e) => {
warn!("UPnP not available: {}", e);
self.upnp_enabled = false;
Err(WireError::nat("UPnP gateway not found"))
}
}
}
/// Enable NAT-PMP port mapping
pub async fn enable_nat_pmp(&mut self) -> Result<()> {
info!("Attempting to enable NAT-PMP");
// Simplified NAT-PMP implementation
// Would involve UDP communication with gateway on port 5351
match self.discover_nat_pmp_gateway().await {
Ok(gateway) => {
info!("Found NAT-PMP gateway: {}", gateway);
self.nat_pmp_enabled = true;
Ok(())
}
Err(e) => {
warn!("NAT-PMP not available: {}", e);
self.nat_pmp_enabled = false;
Err(WireError::nat("NAT-PMP gateway not found"))
}
}
}
/// Attempt hole punching to a remote peer
pub async fn hole_punch(&self, remote_addr: SocketAddr) -> Result<SocketAddr> {
info!("Attempting hole punch to {}", remote_addr);
if self.nat_type == NatType::Symmetric {
warn!("Hole punching unlikely to succeed with symmetric NAT");
}
// Simplified hole punching
// Would involve coordinated punching with the remote peer
let result = timeout(Duration::from_secs(5), self.attempt_punch(remote_addr)).await;
match result {
Ok(Ok(punched_addr)) => {
info!("Hole punch successful: {}", punched_addr);
Ok(punched_addr)
}
Ok(Err(e)) => {
warn!("Hole punch failed: {}", e);
Err(e)
}
Err(_) => {
warn!("Hole punch timed out");
Err(WireError::Timeout)
}
}
}
/// Get the current NAT type
pub fn nat_type(&self) -> NatType {
self.nat_type
}
/// Check if UPnP is enabled
pub fn upnp_enabled(&self) -> bool {
self.upnp_enabled
}
/// Check if NAT-PMP is enabled
pub fn nat_pmp_enabled(&self) -> bool {
self.nat_pmp_enabled
}
/// Check if any automatic port mapping is available
pub fn has_port_mapping(&self) -> bool {
self.upnp_enabled || self.nat_pmp_enabled
}
// Private helper methods
async fn discover_upnp_gateway(&self) -> Result<IpAddr> {
// Simulate UPnP gateway discovery
// In reality, this would use SSDP multicast
tokio::time::sleep(Duration::from_millis(100)).await;
// Return a dummy gateway address for now
Ok("192.168.1.1".parse().unwrap())
}
async fn discover_nat_pmp_gateway(&self) -> Result<IpAddr> {
// Simulate NAT-PMP gateway discovery
// Would try default gateway addresses
tokio::time::sleep(Duration::from_millis(100)).await;
// Return a dummy gateway address for now
Ok("192.168.1.1".parse().unwrap())
}
async fn attempt_punch(&self, remote_addr: SocketAddr) -> Result<SocketAddr> {
// Simulate hole punching attempt
// Would send UDP packets to coordinate with remote peer
tokio::time::sleep(Duration::from_millis(200)).await;
// For simulation, just return the remote address
// In reality, this would return the punched-through address
Ok(remote_addr)
}
}
impl Default for NatTraversal {
fn default() -> Self {
Self::new()
}
}
#[cfg(test)]
mod tests {
use super::*;
#[tokio::test]
async fn test_nat_traversal_creation() {
let nat = NatTraversal::new();
assert_eq!(nat.nat_type(), NatType::Unknown);
assert!(!nat.has_port_mapping());
}
#[tokio::test]
async fn test_nat_type_discovery() {
let mut nat = NatTraversal::new();
// This may fail in test environment if STUN servers are unreachable
// We just want to ensure the method doesn't panic
match nat.discover_nat_type().await {
Ok(nat_type) => assert_ne!(nat_type, NatType::Unknown),
Err(_) => {
// Expected in test environments without internet access
// The important thing is that the method executed without panicking
}
}
}
#[tokio::test]
async fn test_upnp_enablement() {
let mut nat = NatTraversal::new();
// This may fail in test environment, which is expected
let _ = nat.enable_upnp().await;
// Just test that it doesn't panic
}
#[tokio::test]
async fn test_hole_punch() {
let nat = NatTraversal::new();
let remote_addr = "203.0.113.1:8080".parse().unwrap();
// This may fail in test environment, which is expected
let _ = nat.hole_punch(remote_addr).await;
// Just test that it doesn't panic
}
}