Run ss-server on the C++ TCP relay engine

The request header, outbound ACL, target resolution through the relay's
resolver, the anti-probing stop stage and the manager traffic counters
are engine code now; the connmark-to-TOS tracker becomes a pair of relay
hooks. server.cpp keeps option parsing, nftables and the stats timer.

scripts/no_heap_baseline.txt

@@ -15,7 +15,7 @@ src/plugin.cpp 3
 src/process.cpp 26
 src/redir.cpp 15
 src/rule.cpp 2
-src/server.cpp 17
+src/server.cpp 4
 src/ss_event.cpp 5
 src/ssurl.cpp 3
 src/stream.cpp 3

src/relay/tcp.cpp

@@ -374,6 +374,10 @@ bool Connection::client_kind() const noexcept
 
 void Connection::begin_close(CloseCompletion done) noexcept
 {
+    if (hook_state_ != nullptr && relay_->config_.release != nullptr) {
+        relay_->config_.release(hook_state_);
+        hook_state_ = nullptr;
+    }
     done_ = done;
     closer_.arm(CloseCompletion(
         [](void *self, std::uint32_t) {
@@ -1100,6 +1104,9 @@ Flow Connection::pump_to_client() noexcept
             }
         }
         Pull p = pull(upstream_.fd(), decode, to_client_, relay_->config_.rx);
+        if (p == Pull::data && relay_->config_.downstream != nullptr) {
+            relay_->config_.downstream(&hook_state_, client_.fd(), upstream_.fd());
+        }
         switch (p) {
         case Pull::data:
             if (!replied_) {

src/relay/tcp.hpp

@@ -68,6 +68,10 @@ struct TcpConfig {
     void (*on_traffic)() = nullptr;
     // ss-server: a client failed the handshake (logging, nftables).
     void (*report_failure)(ss_socket_t client, const char *reason) = nullptr;
+    // ss-server --connmark-to-TOS: runs before each write to the client
+    // with per-connection state the hook owns, released when it closes.
+    void (*downstream)(void **state, ss_socket_t client, ss_socket_t upstream) = nullptr;
+    void (*release)(void *state) = nullptr;
 };
 
 class TcpRelay;
@@ -154,6 +158,7 @@ private:
     bool dns_done_     = false;
     bool dns_ok_       = false;
     bool replied_      = false; // first upstream bytes reached the client
+    void *hook_state_  = nullptr;
     sockaddr_storage dns_answer_{};
 };
 

src/server.h

@@ -1,125 +0,0 @@
-/*
- * server.h - Define shadowsocks server's buffers and callbacks
- *
- * Copyright (C) 2013 - 2019, Max Lv <max.c.lv@gmail.com>
- *
- * This file is part of the shadowsocks-libev.
- *
- * shadowsocks-libev is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 3 of the License, or
- * (at your option) any later version.
- *
- * shadowsocks-libev is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with shadowsocks-libev; see the file COPYING. If not, see
- * <http://www.gnu.org/licenses/>.
- */
-
-#ifndef _SERVER_H
-#define _SERVER_H
-
-#include <time.h>
-#include "core.h"
-
-#include "ss_event.h"
-
-#ifdef __MINGW32__
-#include "ss_windows.h"
-#endif
-
-#include "crypto.h"
-#include "jconf.h"
-#include "netutils.h"
-
-#include "common.h"
-
-#ifdef __cplusplus
-extern "C" {
-#endif
-
-typedef struct listen_ctx {
-    ss_io io;
-    int fd;
-    int timeout;
-    char *iface;
-    struct ss_loop *loop;
-} listen_ctx_t;
-
-typedef struct server_ctx {
-    ss_io io;
-    ss_timer watcher;
-    int connected;
-    struct server *server;
-} server_ctx_t;
-
-#ifdef USE_NFCONNTRACK_TOS
-
-#include <libnetfilter_conntrack/libnetfilter_conntrack.h>
-#include <libnetfilter_conntrack/libnetfilter_conntrack_tcp.h>
-
-struct dscptracker {
-    struct nf_conntrack *ct;
-    long unsigned int mark;
-    unsigned int dscp;
-    unsigned int packet_count;
-};
-
-#endif
-
-struct query;
-
-typedef struct server {
-    int fd;
-    int stage;
-    int frag;
-
-    buffer_t *buf;
-
-    cipher_ctx_t *e_ctx;
-    cipher_ctx_t *d_ctx;
-    struct server_ctx *recv_ctx;
-    struct server_ctx *send_ctx;
-    struct listen_ctx *listen_ctx;
-    struct remote *remote;
-
-    struct query *query;
-
-    struct ss_list_item entries;
-#ifdef USE_NFCONNTRACK_TOS
-    struct dscptracker *tracker;
-#endif
-} server_t;
-
-typedef struct query {
-    server_t *server;
-    char hostname[MAX_HOSTNAME_LEN];
-} query_t;
-
-typedef struct remote_ctx {
-    ss_io io;
-    int connected;
-    struct remote *remote;
-} remote_ctx_t;
-
-typedef struct remote {
-    int fd;
-#ifdef TCP_FASTOPEN_WINSOCK
-    OVERLAPPED olap;
-    int connect_ex_done;
-#endif
-    buffer_t *buf;
-    struct remote_ctx *recv_ctx;
-    struct remote_ctx *send_ctx;
-    struct server *server;
-} remote_t;
-
-#ifdef __cplusplus
-}
-#endif
-
-#endif // _SERVER_H