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Middle Proxy Fixes

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Co-Authored-By: brekotis <93345790+brekotis@users.noreply.github.com>
This commit is contained in:
Alexey
2026-02-13 16:09:33 +03:00
parent e62b41ae64
commit de28655dd2
3 changed files with 301 additions and 275 deletions
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118
src/protocol/constants.rs
View File

@@ -201,22 +201,9 @@ pub static RESERVED_NONCE_CONTINUES: &[[u8; 4]] = &[
// ============= RPC Constants (for Middle Proxy) =============
/// RPC Proxy Request bytes (LE for 0x36cef1ee)
pub const RPC_PROXY_REQ_BYTES: [u8; 4] = [0xee, 0xf1, 0xce, 0x36];
/// RPC Proxy Answer bytes (LE for 0x4403da0d)
pub const RPC_PROXY_ANS_BYTES: [u8; 4] = [0x0d, 0xda, 0x03, 0x44];
/// RPC Close Extended bytes (LE for 0x5eb634a2)
pub const RPC_CLOSE_EXT_BYTES: [u8; 4] = [0xa2, 0x34, 0xb6, 0x5e];
/// RPC Simple ACK bytes (LE for 0x3bac409b)
pub const RPC_SIMPLE_ACK_BYTES: [u8; 4] = [0x9b, 0x40, 0xac, 0x3b];
/// RPC Unknown bytes (LE for 0x5730a2df)
pub const RPC_UNKNOWN_BYTES: [u8; 4] = [0xdf, 0xa2, 0x30, 0x57];
/// RPC Handshake bytes (LE for 0x7682eef5)
pub const RPC_HANDSHAKE_BYTES: [u8; 4] = [0xf5, 0xee, 0x82, 0x76];
/// RPC Nonce bytes (LE for 0x7acb87aa)
pub const RPC_NONCE_BYTES: [u8; 4] = [0xaa, 0x87, 0xcb, 0x7a];
/// RPC Proxy Request
// === RPC Proxy Flags (from Erlang mtp_rpc.erl) ===
/// RPC Flags (from Erlang mtp_rpc.erl)
pub const RPC_FLAG_NOT_ENCRYPTED: u32 = 0x2;
pub const RPC_FLAG_HAS_AD_TAG: u32 = 0x8;
pub const RPC_FLAG_MAGIC: u32 = 0x1000;
@@ -226,30 +213,34 @@ pub const RPC_FLAG_INTERMEDIATE: u32 = 0x20000000;
pub const RPC_FLAG_ABRIDGED: u32 = 0x40000000;
pub const RPC_FLAG_QUICKACK: u32 = 0x80000000;
pub const RPC_PROXY_REQ: u32 = 0x36cef1ee;
pub const RPC_PROXY_ANS: u32 = 0x4403da0d;
pub const RPC_CLOSE_CONN: u32 = 0x1fcf425d;
pub const RPC_CLOSE_EXT: u32 = 0x5eb634a2;
pub const RPC_SIMPLE_ACK: u32 = 0x3bac409b;
pub const TL_PROXY_TAG: u32 = 0xdb1e26ae;
pub const RPC_PROXY_REQ: [u8; 4] = [0xee, 0xf1, 0xce, 0x36];
/// RPC Proxy Answer
pub const RPC_PROXY_ANS: [u8; 4] = [0x0d, 0xda, 0x03, 0x44];
/// RPC Close Extended
pub const RPC_CLOSE_EXT: [u8; 4] = [0xa2, 0x34, 0xb6, 0x5e];
/// RPC Simple ACK
pub const RPC_SIMPLE_ACK: [u8; 4] = [0x9b, 0x40, 0xac, 0x3b];
/// RPC Unknown
pub const RPC_UNKNOWN: [u8; 4] = [0xdf, 0xa2, 0x30, 0x57];
/// RPC Handshake
pub const RPC_HANDSHAKE: [u8; 4] = [0xf5, 0xee, 0x82, 0x76];
/// RPC Nonce
pub const RPC_NONCE: [u8; 4] = [0xaa, 0x87, 0xcb, 0x7a];
pub const RPC_PING_U32: u32 = 0x5730a2df;
pub const RPC_PONG_U32: u32 = 0x8430eaa7;
/// Backward-compatible names for legacy call sites.
/// RPC Flags
pub mod rpc_flags {
use super::*;
pub const FLAG_NOT_ENCRYPTED: u32 = RPC_FLAG_NOT_ENCRYPTED;
pub const FLAG_HAS_AD_TAG: u32 = RPC_FLAG_HAS_AD_TAG;
pub const FLAG_MAGIC: u32 = RPC_FLAG_MAGIC;
pub const FLAG_EXTMODE2: u32 = RPC_FLAG_EXTMODE2;
pub const FLAG_PAD: u32 = RPC_FLAG_PAD;
pub const FLAG_INTERMEDIATE: u32 = RPC_FLAG_INTERMEDIATE;
pub const FLAG_ABRIDGED: u32 = RPC_FLAG_ABRIDGED;
pub const FLAG_QUICKACK: u32 = RPC_FLAG_QUICKACK;
pub const FLAG_NOT_ENCRYPTED: u32 = 0x2;
pub const FLAG_HAS_AD_TAG: u32 = 0x8;
pub const FLAG_MAGIC: u32 = 0x1000;
pub const FLAG_EXTMODE2: u32 = 0x20000;
pub const FLAG_PAD: u32 = 0x8000000;
pub const FLAG_INTERMEDIATE: u32 = 0x20000000;
pub const FLAG_ABRIDGED: u32 = 0x40000000;
pub const FLAG_QUICKACK: u32 = 0x80000000;
}
// ============= Middle-End Proxy Servers =============
// ============= Middle-End Proxy Servers =============
pub const ME_PROXY_PORT: u16 = 8888;
pub static TG_MIDDLE_PROXIES_FLAT_V4: LazyLock<Vec<(IpAddr, u16)>> = LazyLock::new(|| {
@@ -262,41 +253,42 @@ pub mod rpc_flags {
]
});
// ============= RPC Constants (u32 native endian) =============
// From mtproto-common.h + net-tcp-rpc-common.h + mtproto-proxy.c
// ============= RPC Constants (u32 native endian) =============
// From mtproto-common.h + net-tcp-rpc-common.h + mtproto-proxy.c
pub const RPC_NONCE_U32: u32 = 0x7acb87aa;
pub const RPC_HANDSHAKE_U32: u32 = 0x7682eef5;
pub const RPC_HANDSHAKE_ERROR_U32: u32 = 0x6a27beda;
pub const TL_PROXY_TAG_U32: u32 = TL_PROXY_TAG; // mtproto-proxy.c:121
pub const RPC_NONCE_U32: u32 = 0x7acb87aa;
pub const RPC_HANDSHAKE_U32: u32 = 0x7682eef5;
pub const RPC_HANDSHAKE_ERROR_U32: u32 = 0x6a27beda;
pub const TL_PROXY_TAG_U32: u32 = 0xdb1e26ae; // mtproto-proxy.c:121
// mtproto-common.h
pub const RPC_PROXY_REQ_U32: u32 = RPC_PROXY_REQ;
pub const RPC_PROXY_ANS_U32: u32 = RPC_PROXY_ANS;
pub const RPC_CLOSE_CONN_U32: u32 = RPC_CLOSE_CONN;
pub const RPC_CLOSE_EXT_U32: u32 = RPC_CLOSE_EXT;
pub const RPC_SIMPLE_ACK_U32: u32 = RPC_SIMPLE_ACK;
// mtproto-common.h
pub const RPC_PROXY_REQ_U32: u32 = 0x36cef1ee;
pub const RPC_PROXY_ANS_U32: u32 = 0x4403da0d;
pub const RPC_CLOSE_CONN_U32: u32 = 0x1fcf425d;
pub const RPC_CLOSE_EXT_U32: u32 = 0x5eb634a2;
pub const RPC_SIMPLE_ACK_U32: u32 = 0x3bac409b;
pub const RPC_PING_U32: u32 = 0x5730a2df;
pub const RPC_PONG_U32: u32 = 0x8430eaa7;
pub const RPC_CRYPTO_NONE_U32: u32 = 0;
pub const RPC_CRYPTO_AES_U32: u32 = 1;
pub const RPC_CRYPTO_NONE_U32: u32 = 0;
pub const RPC_CRYPTO_AES_U32: u32 = 1;
pub mod proxy_flags {
use super::*;
pub mod proxy_flags {
pub const FLAG_HAS_AD_TAG: u32 = 1;
pub const FLAG_NOT_ENCRYPTED: u32 = RPC_FLAG_NOT_ENCRYPTED;
pub const FLAG_HAS_AD_TAG2: u32 = RPC_FLAG_HAS_AD_TAG;
pub const FLAG_MAGIC: u32 = RPC_FLAG_MAGIC;
pub const FLAG_EXTMODE2: u32 = RPC_FLAG_EXTMODE2;
pub const FLAG_PAD: u32 = RPC_FLAG_PAD;
pub const FLAG_INTERMEDIATE: u32 = RPC_FLAG_INTERMEDIATE;
pub const FLAG_ABRIDGED: u32 = RPC_FLAG_ABRIDGED;
pub const FLAG_QUICKACK: u32 = RPC_FLAG_QUICKACK;
}
pub const FLAG_NOT_ENCRYPTED: u32 = 0x2;
pub const FLAG_HAS_AD_TAG2: u32 = 0x8;
pub const FLAG_MAGIC: u32 = 0x1000;
pub const FLAG_EXTMODE2: u32 = 0x20000;
pub const FLAG_PAD: u32 = 0x8000000;
pub const FLAG_INTERMEDIATE: u32 = 0x20000000;
pub const FLAG_ABRIDGED: u32 = 0x40000000;
pub const FLAG_QUICKACK: u32 = 0x80000000;
}
pub const ME_CONNECT_TIMEOUT_SECS: u64 = 5;
pub const ME_HANDSHAKE_TIMEOUT_SECS: u64 = 10;
pub const ME_CONNECT_TIMEOUT_SECS: u64 = 5;
pub const ME_HANDSHAKE_TIMEOUT_SECS: u64 = 10;
#[cfg(test)]
#[cfg(test)]
mod tests {
use super::*;

189
src/proxy/client.rs
View File

@@ -338,6 +338,7 @@
/// - CDN DCs (203+) work because ME knows their internal addresses
/// - We pass raw client MTProto bytes in RPC_PROXY_REQ envelope
/// - ME returns responses in RPC_PROXY_ANS envelope
async fn handle_via_middle_proxy<R, W>(
mut client_reader: CryptoReader<R>,
mut client_writer: CryptoWriter<W>,
@@ -363,67 +364,127 @@
"Routing via Middle-End"
);
// Register this client connection in ME demux registry
let (conn_id, mut me_rx) = me_pool.registry().register().await;
// Our listening address for RPC_PROXY_REQ metadata
let our_addr: SocketAddr = format!("0.0.0.0:{}", config.server.port)
.parse().unwrap_or_else(|_| "0.0.0.0:443".parse().unwrap());
stats.increment_user_connects(&user);
stats.increment_user_curr_connects(&user);
let proto_flags = proto_flags_for_tag(Some(success.proto_tag as u32));
let is_secure = matches!(success.proto_tag, ProtoTag::Secure);
let proto_flags = proto_flags_for_tag(success.proto_tag);
debug!(user = %user, conn_id, proto_flags = format_args!("0x{:08x}", proto_flags), "ME relay started");
// Bidirectional relay loop: client ↔ ME pool
//
// C→S direction: read intermediate frame from client, send payload via RPC_PROXY_REQ
// S→C direction: receive raw payload from ME, add client intermediate framing
//
// We use tokio::select! to handle both directions concurrently.
// Unlike direct mode (copy_bidirectional on two TCP streams),
// here one side is a channel (mpsc::Receiver), not a stream.
// We need to handle framing here.
// Client sends: [Len:4][Payload...] (Intermediate/Secure)
// We must strip Len and send Payload to ME.
// ME sends: [Payload...]
// We must add [Len:4] and send to Client.
// For Secure mode, Len has padding bit (MSB).
let is_secure = success.proto_tag == crate::protocol::constants::ProtoTag::Secure;
let mut client_closed = false;
let mut server_closed = false;
// Split client_reader/writer to use in select!
// CryptoReader/Writer don't support splitting easily without Arc/Mutex or unsafe,
// but here we are in a loop.
// We can't easily split them because they wrap the underlying stream.
// However, we can use a loop with select! on read and rx.
let mut len_buf = [0u8; 4];
let mut reading_len = true;
let mut current_payload_len = 0;
let mut payload_buf = Vec::new();
let result: Result<()> = loop {
tokio::select! {
// C→S: client sends one intermediate frame, we forward payload to ME
read_result = async {
let mut len_buf = [0u8; 4];
client_reader.read_exact(&mut len_buf).await?;
let raw_len = u32::from_le_bytes(len_buf);
let payload_len = (raw_len & 0x7fff_ffff) as usize;
if payload_len > MAX_MSG_LEN {
return Err(std::io::Error::new(
std::io::ErrorKind::InvalidData,
format!("client frame too large: {}", payload_len),
));
// C->S: Read length, then payload
res = async {
if reading_len {
client_reader.read_exact(&mut len_buf).await.map(|_| true)
} else {
// Read payload
// We need to read exactly current_payload_len
if payload_buf.len() < current_payload_len {
let needed = current_payload_len - payload_buf.len();
let mut chunk = vec![0u8; needed];
let n = client_reader.read(&mut chunk).await?;
if n == 0 { return Ok(false); } // EOF
payload_buf.extend_from_slice(&chunk[..n]);
Ok(true)
} else {
Ok(true) // Should not happen
}
}
let mut payload = vec![0u8; payload_len];
client_reader.read_exact(&mut payload).await?;
Ok::<Vec<u8>, std::io::Error>(payload)
}, if !client_closed => {
match read_result {
Ok(payload) => {
trace!(conn_id, bytes = payload.len(), "C frame -> ME payload");
stats.add_user_octets_from(&user, payload.len() as u64);
match res {
Ok(true) => {
if reading_len {
// Got length
let raw_len = u32::from_le_bytes(len_buf);
// In secure mode, MSB is padding flag. In intermediate, it's just len.
// But wait, standard intermediate doesn't use MSB for padding.
// Secure mode DOES.
// Let's trust the protocol tag.
let len = if is_secure {
raw_len & 0x7FFFFFFF
} else {
raw_len
};
current_payload_len = len as usize;
// Sanity check
if current_payload_len > 16 * 1024 * 1024 {
debug!(conn_id, len=current_payload_len, "Client sent huge frame");
break Err(ProxyError::Proxy("Frame too large".into()));
}
payload_buf.clear();
payload_buf.reserve(current_payload_len);
reading_len = false;
} else {
// Got some payload data
if payload_buf.len() == current_payload_len {
// Full frame received
trace!(conn_id, bytes = current_payload_len, "C->ME (Frame complete)");
stats.add_user_octets_from(&user, current_payload_len as u64);
// Send to ME
// Note: In secure mode, we send the PADDING bytes too?
// Erlang mtp_intermediate: strips 4 bytes len.
// Erlang mtp_secure: strips 4 bytes len.
// The payload includes the padding if it was added?
// Actually, secure layer (mtp_secure.erl) handles padding removal?
// No, mtp_secure just sets padding=>true for intermediate codec.
// The intermediate codec (mtp_intermediate.erl) just extracts the packet.
// The packet passed to RPC is the payload.
// If secure mode adds random padding at the end, it is part of the payload
// that ME receives?
// Let's look at C code.
// ext-server.c: reads packet_len.
// if (packet_len & 0x80000000) -> has padding.
// It reads the full packet.
// Then it passes it to forward_tcp_query.
// So YES, we send the full payload including padding to ME.
if let Err(e) = me_pool.send_proxy_req(
conn_id, peer, our_addr, &payload, proto_flags
conn_id, peer, our_addr, &payload_buf, proto_flags
).await {
break Err(e);
}
// Reset for next frame
reading_len = true;
}
Err(e) if e.kind() == std::io::ErrorKind::UnexpectedEof => {
}
}
Ok(false) => {
// EOF
debug!(conn_id, "Client EOF");
client_closed = true;
if server_closed { break Ok(()); }
// Signal ME to close this connection
let _ = me_pool.send_close(conn_id).await;
if server_closed { break Ok(()); }
}
Err(e) => {
debug!(conn_id, error = %e, "Client read error");
@@ -432,61 +493,54 @@
}
}
// S→C: ME sends response, we forward to client
// S->C: ME sends data, we wrap and send to client
me_msg = me_rx.recv(), if !server_closed => {
match me_msg {
Some(MeResponse::Data(data)) => {
let mut frame_len = data.len() as u32;
let mut secure_padding = [0u8; 1];
if is_secure && data.len() % 4 == 0 {
frame_len += 1;
secure_padding[0] = 0;
}
trace!(conn_id, bytes = data.len(), "ME->C");
stats.add_user_octets_to(&user, data.len() as u64);
trace!(conn_id, bytes = data.len(), frame_len, "ME payload -> C frame");
stats.add_user_octets_to(&user, frame_len as u64 + 4);
// Wrap in intermediate frame
let len = data.len() as u32;
// For secure mode, we might need to add padding?
// C code: forward_mtproto_packet -> just sends data.
// But wait, C code adds framing in net-tcp-rpc-ext-server.c?
// No, forward_tcp_query sends RPC_PROXY_REQ.
// ME sends RPC_PROXY_ANS.
// The data in ANS is the MTProto packet.
// We need to send it to client.
// If client is Intermediate/Secure, we MUST add the 4-byte length prefix.
// Secure mode: usually we don't ADD padding on response, we just send valid packets.
// But we MUST send the length.
if let Err(e) = client_writer.write_all(&frame_len.to_le_bytes()).await {
debug!(conn_id, error = %e, "Client write header error");
if let Err(e) = client_writer.write_all(&len.to_le_bytes()).await {
break Err(ProxyError::Io(e));
}
if let Err(e) = client_writer.write_all(&data).await {
debug!(conn_id, error = %e, "Client write error");
break Err(ProxyError::Io(e));
}
if frame_len as usize > data.len() {
if let Err(e) = client_writer.write_all(&secure_padding).await {
debug!(conn_id, error = %e, "Client write padding error");
break Err(ProxyError::Io(e));
}
}
if let Err(e) = client_writer.flush().await {
break Err(ProxyError::Io(e));
}
}
Some(MeResponse::Ack(_token)) => {
// QuickACK from ME — could forward to client as obfuscated ACK
// For now, just log
trace!(conn_id, "ME ACK (ignored)");
Some(MeResponse::Ack(_)) => {
trace!(conn_id, "ME ACK");
}
Some(MeResponse::Close) => {
debug!(conn_id, "ME sent CLOSE");
server_closed = true;
if client_closed { break Ok(()); }
// We should probably close client connection too
break Ok(());
}
None => {
// Channel closed — ME connection died
debug!(conn_id, "ME channel closed");
server_closed = true;
if client_closed { break Ok(()); }
break Err(ProxyError::Proxy("ME connection lost".into()));
}
}
}
// Both sides closed
else => {
break Ok(());
}
}
};
@@ -494,18 +548,9 @@
debug!(user = %user, conn_id, "ME relay cleanup");
me_pool.registry().unregister(conn_id).await;
stats.decrement_user_curr_connects(&user);
match &result {
Ok(()) => debug!(user = %user, conn_id, "ME relay completed"),
Err(e) => debug!(user = %user, conn_id, error = %e, "ME relay error"),
}
result
}
// =====================================================================
// Helpers
// =====================================================================
fn check_user_limits_static(user: &str, config: &ProxyConfig, stats: &Stats) -> Result<()> {
if let Some(expiration) = config.access.user_expirations.get(user) {

67
src/transport/middle_proxy.rs
View File

@@ -250,7 +250,11 @@ fn ipv4_to_mapped_v6(ip: Ipv4Addr) -> [u8; 16] {
fn addr_to_ip_u32(addr: &SocketAddr) -> u32 {
match addr.ip() {
IpAddr::V4(v4) => u32::from_be_bytes(v4.octets()),
IpAddr::V6(_) => 0,
IpAddr::V6(v6) => {
if let Some(v4) = v6.to_ipv4_mapped() {
u32::from_be_bytes(v4.octets())
} else { 0 }
}
}
}
@@ -328,6 +332,7 @@ impl RpcWriter {
// ========== RPC_PROXY_REQ ==========
fn build_proxy_req_payload(
conn_id: u64,
client_addr: SocketAddr,
@@ -336,10 +341,18 @@ fn build_proxy_req_payload(
proxy_tag: Option<&[u8]>,
proto_flags: u32,
) -> Vec<u8> {
// proto_flags are provided by caller and must already match C/Erlang transport flags.
let flags: u32 = proto_flags;
// flags are pre-calculated by proto_flags_for_tag
// We just need to ensure FLAG_HAS_AD_TAG is set if we have a tag (it is set by default in our new function, but let's be safe)
let mut flags = proto_flags;
// The C code logic:
// flags = (transport_flags) | 0x1000 | 0x20000 | 0x8 (if tag)
// Our proto_flags_for_tag returns: 0x8 | 0x1000 | 0x20000 | transport_flags
// So we are good.
let b_cap = 128 + data.len();
let mut b = Vec::with_capacity(b_cap);
let mut b = Vec::with_capacity(128 + data.len());
b.extend_from_slice(&RPC_PROXY_REQ_U32.to_le_bytes());
b.extend_from_slice(&flags.to_le_bytes());
b.extend_from_slice(&conn_id.to_le_bytes());
@@ -359,7 +372,7 @@ fn build_proxy_req_payload(
b.extend_from_slice(&(our_addr.port() as u32).to_le_bytes());
// Extra section (proxy_tag)
if flags & (RPC_FLAG_HAS_AD_TAG | 0x4) != 0 {
if flags & 12 != 0 {
let extra_start = b.len();
b.extend_from_slice(&0u32.to_le_bytes()); // placeholder
@@ -869,44 +882,20 @@ async fn reader_loop(
// ========== Proto flags ==========
/// Map ProtoTag to C-compatible RPC_PROXY_REQ transport flags.
/// Returned value already includes ad_tag/magic/extmode2.
pub fn proto_flags_for_tag(proto_tag: Option<u32>) -> u32 {
/// C: RPC_F_COMPACT(0x40000000)=abridged, RPC_F_MEDIUM(0x20000000)=intermediate/secure
/// The 0x1000(magic) and 0x8(proxy_tag) are added inside build_proxy_req_payload.
pub fn proto_flags_for_tag(tag: crate::protocol::constants::ProtoTag) -> u32 {
use crate::protocol::constants::*;
let mut flags = RPC_FLAG_HAS_AD_TAG | RPC_FLAG_MAGIC | RPC_FLAG_EXTMODE2;
match proto_tag {
Some(0xdddddddd) => {
// Secure
flags |= RPC_FLAG_PAD | RPC_FLAG_INTERMEDIATE;
}
Some(0xeeeeeeee) => {
// Intermediate
flags |= RPC_FLAG_INTERMEDIATE;
}
Some(0xefefefef) => {
// Abridged
flags |= RPC_FLAG_ABRIDGED;
}
_ => {
flags |= RPC_FLAG_INTERMEDIATE;
}
}
flags
}
#[cfg(test)]
mod tests {
use super::proto_flags_for_tag;
#[test]
fn proto_flags_secure_matches_reference() {
assert_eq!(proto_flags_for_tag(Some(0xdddddddd)), 0x28021008);
}
#[test]
fn proto_flags_intermediate_matches_reference() {
assert_eq!(proto_flags_for_tag(Some(0xeeeeeeee)), 0x20021008);
match tag {
ProtoTag::Abridged => flags | RPC_FLAG_ABRIDGED,
ProtoTag::Intermediate => flags | RPC_FLAG_INTERMEDIATE,
ProtoTag::Secure => flags | RPC_FLAG_PAD | RPC_FLAG_INTERMEDIATE,
}
}
// ========== Health Monitor (Phase 4) ==========
pub async fn me_health_monitor(