Normalize IP + Masking + TLS

src/config/load.rs

@@ -194,6 +194,10 @@ impl ProxyConfig {
 
         validate_network_cfg(&mut config.network)?;
 
+        if config.general.use_middle_proxy && config.network.ipv6 == Some(true) {
+            warn!("IPv6 with Middle Proxy is experimental and may cause KDF address mismatch; consider disabling IPv6 or ME");
+        }
+
         // Random fake_cert_len only when default is in use.
         if !config.censorship.tls_emulation && config.censorship.fake_cert_len == default_fake_cert_len() {
             config.censorship.fake_cert_len = rand::rng().gen_range(1024..4096);

src/main.rs

@@ -3,6 +3,7 @@
 use std::net::SocketAddr;
 use std::sync::Arc;
 use std::time::Duration;
+use rand::Rng;
 use tokio::net::TcpListener;
 use tokio::signal;
 use tokio::sync::Semaphore;
@@ -275,11 +276,9 @@ async fn main() -> std::result::Result<(), Box<dyn std::error::Error>> {
             &config.censorship.tls_front_dir,
         ));
 
-        let cache_clone = cache.clone();
-        let domains = tls_domains.clone();
         let port = config.censorship.mask_port;
-        tokio::spawn(async move {
+        // Initial synchronous fetch to warm cache before serving clients.
-            for domain in domains {
+        for domain in tls_domains.clone() {
             match crate::tls_front::fetcher::fetch_real_tls(
                 &domain,
                 port,
@@ -288,10 +287,33 @@ async fn main() -> std::result::Result<(), Box<dyn std::error::Error>> {
             )
             .await
             {
-                    Ok(res) => cache_clone.update_from_fetch(&domain, res).await,
+                Ok(res) => cache.update_from_fetch(&domain, res).await,
                 Err(e) => warn!(domain = %domain, error = %e, "TLS emulation fetch failed"),
             }
         }
+
+        // Periodic refresh with jitter.
+        let cache_clone = cache.clone();
+        let domains = tls_domains.clone();
+        tokio::spawn(async move {
+            loop {
+                let base_secs = rand::rng().random_range(4 * 3600..=6 * 3600);
+                let jitter_secs = rand::rng().random_range(0..=7200);
+                tokio::time::sleep(Duration::from_secs(base_secs + jitter_secs)).await;
+                for domain in &domains {
+                    match crate::tls_front::fetcher::fetch_real_tls(
+                        domain,
+                        port,
+                        domain,
+                        Duration::from_secs(5),
+                    )
+                    .await
+                    {
+                        Ok(res) => cache_clone.update_from_fetch(domain, res).await,
+                        Err(e) => warn!(domain = %domain, error = %e, "TLS emulation refresh failed"),
+                    }
+                }
+            }
         });
 
         Some(cache)

src/protocol/tls.rs

@@ -351,6 +351,9 @@ pub fn build_server_hello(
     fake_cert_len: usize,
     rng: &SecureRandom,
 ) -> Vec<u8> {
+    const MIN_APP_DATA: usize = 64;
+    const MAX_APP_DATA: usize = 16640; // RFC 8446 §5.2 upper bound
+    let fake_cert_len = fake_cert_len.max(MIN_APP_DATA).min(MAX_APP_DATA);
     let x25519_key = gen_fake_x25519_key(rng);
     
     // Build ServerHello
@@ -373,7 +376,13 @@ pub fn build_server_hello(
     app_data_record.push(TLS_RECORD_APPLICATION);
     app_data_record.extend_from_slice(&TLS_VERSION);
     app_data_record.extend_from_slice(&(fake_cert_len as u16).to_be_bytes());
+    if fake_cert_len > 17 {
+        app_data_record.extend_from_slice(&fake_cert[..fake_cert_len - 17]);
+        app_data_record.push(0x16); // inner content type marker
+        app_data_record.extend_from_slice(&rng.bytes(16)); // AEAD-like tag mimic
+    } else {
         app_data_record.extend_from_slice(&fake_cert);
+    }
     
     // Combine all records
     let mut response = Vec::with_capacity(

src/proxy/client.rs

@@ -31,6 +31,7 @@ use crate::stats::{ReplayChecker, Stats};
 use crate::stream::{BufferPool, CryptoReader, CryptoWriter};
 use crate::transport::middle_proxy::MePool;
 use crate::transport::{UpstreamManager, configure_client_socket, parse_proxy_protocol};
+use crate::transport::socket::normalize_ip;
 use crate::tls_front::TlsFrontCache;
 
 use crate::proxy::direct_relay::handle_via_direct;
@@ -55,7 +56,7 @@ where
     S: AsyncRead + AsyncWrite + Unpin + Send + 'static,
 {
     stats.increment_connects_all();
-    let mut real_peer = peer;
+    let mut real_peer = normalize_ip(peer);
 
     if config.server.proxy_protocol {
         match parse_proxy_protocol(&mut stream, peer).await {
@@ -66,7 +67,7 @@ where
                     version = info.version,
                     "PROXY protocol header parsed"
                 );
-                real_peer = info.src_addr;
+                real_peer = normalize_ip(info.src_addr);
             }
             Err(e) => {
                 stats.increment_connects_bad();
@@ -264,6 +265,7 @@ impl RunningClientHandler {
     pub async fn run(mut self) -> Result<()> {
         self.stats.increment_connects_all();
 
+        self.peer = normalize_ip(self.peer);
         let peer = self.peer;
         let ip_tracker = self.ip_tracker.clone();
         debug!(peer = %peer, "New connection");
@@ -310,7 +312,7 @@ impl RunningClientHandler {
                         version = info.version,
                         "PROXY protocol header parsed"
                     );
-                    self.peer = info.src_addr;
+                    self.peer = normalize_ip(info.src_addr);
                 }
                 Err(e) => {
                     self.stats.increment_connects_bad();

src/proxy/masking.rs

@@ -1,7 +1,7 @@
 //! Masking - forward unrecognized traffic to mask host
 
-use std::time::Duration;
 use std::str;
+use std::time::Duration;
 use tokio::net::TcpStream;
 #[cfg(unix)]
 use tokio::net::UnixStream;
@@ -11,9 +11,9 @@ use tracing::debug;
 use crate::config::ProxyConfig;
 
 const MASK_TIMEOUT: Duration = Duration::from_secs(5);
-    /// Maximum duration for the entire masking relay.
+/// Maximum duration for the entire masking relay.
-    /// Limits resource consumption from slow-loris attacks and port scanners.
+/// Limits resource consumption from slow-loris attacks and port scanners.
-    const MASK_RELAY_TIMEOUT: Duration = Duration::from_secs(60);
+const MASK_RELAY_TIMEOUT: Duration = Duration::from_secs(60);
 const MASK_BUFFER_SIZE: usize = 8192;
 
 /// Detect client type based on initial data
@@ -78,7 +78,9 @@ where
         match connect_result {
             Ok(Ok(stream)) => {
                 let (mask_read, mask_write) = stream.into_split();
-                relay_to_mask(reader, writer, mask_read, mask_write, initial_data).await;
+                if timeout(MASK_RELAY_TIMEOUT, relay_to_mask(reader, writer, mask_read, mask_write, initial_data)).await.is_err() {
+                    debug!("Mask relay timed out (unix socket)");
+                }
             }
             Ok(Err(e)) => {
                 debug!(error = %e, "Failed to connect to mask unix socket");
@@ -110,7 +112,9 @@ where
     match connect_result {
         Ok(Ok(stream)) => {
             let (mask_read, mask_write) = stream.into_split();
-            relay_to_mask(reader, writer, mask_read, mask_write, initial_data).await;
+            if timeout(MASK_RELAY_TIMEOUT, relay_to_mask(reader, writer, mask_read, mask_write, initial_data)).await.is_err() {
+                debug!("Mask relay timed out");
+            }
         }
         Ok(Err(e)) => {
             debug!(error = %e, "Failed to connect to mask host");

src/tls_front/emulator.rs

@@ -5,6 +5,28 @@ use crate::protocol::constants::{
 use crate::protocol::tls::{TLS_DIGEST_LEN, TLS_DIGEST_POS, gen_fake_x25519_key};
 use crate::tls_front::types::CachedTlsData;
 
+const MIN_APP_DATA: usize = 64;
+const MAX_APP_DATA: usize = 16640; // RFC 8446 §5.2 allows up to 2^14 + 256
+
+fn jitter_and_clamp_sizes(sizes: &[usize], rng: &SecureRandom) -> Vec<usize> {
+    sizes
+        .iter()
+        .map(|&size| {
+            let base = size.max(MIN_APP_DATA).min(MAX_APP_DATA);
+            let jitter_range = ((base as f64) * 0.03).round() as i64;
+            if jitter_range == 0 {
+                return base;
+            }
+            let mut rand_bytes = [0u8; 2];
+            rand_bytes.copy_from_slice(&rng.bytes(2));
+            let span = 2 * jitter_range + 1;
+            let delta = (u16::from_le_bytes(rand_bytes) as i64 % span) - jitter_range;
+            let adjusted = (base as i64 + delta).clamp(MIN_APP_DATA as i64, MAX_APP_DATA as i64);
+            adjusted as usize
+        })
+        .collect()
+}
+
 /// Build a ServerHello + CCS + ApplicationData sequence using cached TLS metadata.
 pub fn build_emulated_server_hello(
     secret: &[u8],
@@ -76,6 +98,7 @@ pub fn build_emulated_server_hello(
     if sizes.is_empty() {
         sizes.push(cached.total_app_data_len.max(1024));
     }
+    let sizes = jitter_and_clamp_sizes(&sizes, rng);
 
     let mut app_data = Vec::new();
     for size in sizes {
@@ -83,7 +106,14 @@ pub fn build_emulated_server_hello(
         rec.push(TLS_RECORD_APPLICATION);
         rec.extend_from_slice(&TLS_VERSION);
         rec.extend_from_slice(&(size as u16).to_be_bytes());
+        if size > 17 {
+            let body_len = size - 17;
+            rec.extend_from_slice(&rng.bytes(body_len));
+            rec.push(0x16); // inner content type marker (handshake)
+            rec.extend_from_slice(&rng.bytes(16)); // AEAD-like tag
+        } else {
             rec.extend_from_slice(&rng.bytes(size));
+        }
         app_data.extend_from_slice(&rec);
     }
 

src/tls_front/fetcher.rs

@@ -15,7 +15,7 @@ use rustls::pki_types::{CertificateDer, ServerName, UnixTime};
 use rustls::{DigitallySignedStruct, Error as RustlsError};
 
 use crate::crypto::SecureRandom;
-use crate::protocol::constants::{TLS_RECORD_APPLICATION, TLS_RECORD_HANDSHAKE, TLS_VERSION};
+use crate::protocol::constants::{TLS_RECORD_APPLICATION, TLS_RECORD_HANDSHAKE};
 use crate::tls_front::types::{ParsedServerHello, TlsExtension, TlsFetchResult};
 
 /// No-op verifier: accept any certificate (we only need lengths and metadata).
@@ -163,13 +163,16 @@ fn build_client_hello(sni: &str, rng: &SecureRandom) -> Vec<u8> {
     exts.extend_from_slice(alpn_proto);
 
     // padding to reduce recognizability and keep length ~500 bytes
-    if exts.len() < 180 {
+    const TARGET_EXT_LEN: usize = 180;
-        let pad_len = 180 - exts.len();
+    if exts.len() < TARGET_EXT_LEN {
+        let remaining = TARGET_EXT_LEN - exts.len();
+        if remaining > 4 {
+            let pad_len = remaining - 4; // minus type+len
             exts.extend_from_slice(&0x0015u16.to_be_bytes()); // padding extension
-        exts.extend_from_slice(&(pad_len as u16 + 2).to_be_bytes());
             exts.extend_from_slice(&(pad_len as u16).to_be_bytes());
             exts.resize(exts.len() + pad_len, 0);
         }
+    }
 
     // Extensions length prefix
     body.extend_from_slice(&(exts.len() as u16).to_be_bytes());