1 files changed, 173 insertions, 0 deletions
diff --git a/src/platform/linux/iptables.rs b/src/platform/linux/iptables.rs
new file mode 100644
index 0000000..91fa1da
--- /dev/null
+++ b/src/platform/linux/iptables.rs
@@ -0,0 +1,173 @@
+// SPDX-FileCopyrightText: 2026 Dilluti0n <[email protected]>
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+use anyhow::{Result, Error};
+
+use std::sync::{
+    atomic::{AtomicBool, Ordering}
+};
+
+use crate::{log::LogLevel, log_println, opt};
+use super::{exec_process, INJECT_MARK, IS_U32_SUPPORTED};
+
+static IS_XT_U32_LOADED_BY_US: AtomicBool = AtomicBool::new(false);
+
+const DPIBREAK_CHAIN: &str = "DPIBREAK";
+
+pub struct IPTables {
+    cmd: &'static str,
+}
+
+impl IPTables {
+    pub fn new(is_ipv6: bool) -> Result<Self> {
+        Ok(Self {
+            cmd: if is_ipv6 { "ip6tables" } else { "iptables" },
+        })
+    }
+
+    fn run(&self, args: &[&str]) -> Result<()> {
+        let mut full_args = Vec::with_capacity(args.len() + 1);
+
+        full_args.push(self.cmd);
+        full_args.extend_from_slice(args);
+
+        exec_process(&full_args, None)
+    }
+
+    pub fn new_chain(&self, table: &str, chain: &str) -> Result<()> {
+        self.run(&["-t", table, "-N", chain])
+    }
+
+    pub fn flush_chain(&self, table: &str, chain: &str) -> Result<()> {
+        self.run(&["-t", table, "-F", chain])
+    }
+
+    pub fn delete_chain(&self, table: &str, chain: &str) -> Result<()> {
+        self.run(&["-t", table, "-X", chain])
+    }
+
+    pub fn insert(&self, table: &str, chain: &str, rule: &[&str], pos: i32) -> Result<()> {
+        let pos_str = pos.to_string();
+        let mut args = vec!["-t", table, "-I", chain, &pos_str];
+        args.extend_from_slice(rule);
+        self.run(&args)
+    }
+
+    pub fn append(&self, table: &str, chain: &str, rule: &[&str]) -> Result<()> {
+        let mut args = vec!["-t", table, "-A", chain];
+        args.extend_from_slice(rule);
+        self.run(&args)
+    }
+
+    pub fn delete(&self, table: &str, chain: &str, rule: &[&str]) -> Result<()> {
+        let mut args = vec!["-t", table, "-D", chain];
+        args.extend_from_slice(rule);
+        self.run(&args)
+    }
+}
+
+fn is_xt_u32_loaded() -> bool {
+    std::fs::read_to_string("/proc/modules")
+        .map(|s| s.lines().any(|l| l.starts_with("xt_u32 ")))
+        .unwrap_or(false)
+}
+
+fn ensure_xt_u32() -> Result<()> {
+    let before = is_xt_u32_loaded();
+    _ = exec_process(&["modprobe", "-q", "xt_u32"], None);
+    let after = is_xt_u32_loaded();
+
+    if !before && after {
+        IS_XT_U32_LOADED_BY_US.store(true, Ordering::Relaxed);
+    }
+    Ok(())
+}
+
+fn is_u32_supported(ipt: &IPTables) -> bool {
+    if IS_U32_SUPPORTED.load(Ordering::Relaxed) {
+        return true;
+    }
+
+    if ensure_xt_u32().is_err() {
+        log_println!(LogLevel::Warning, "xt_u32 not supported");
+        return false;
+    }
+
+    log_println!(LogLevel::Info, "xt_u32 loaded");
+
+    let rule = ["-m", "u32", "--u32", "0x0=0x0", "-j", "RETURN"];
+
+    match ipt.insert("raw", "PREROUTING", &rule, 1) {
+        Ok(_) => {
+            _ = ipt.delete("raw", "PREROUTING", &rule);
+            IS_U32_SUPPORTED.store(true, Ordering::Relaxed);
+            true
+        }
+
+        Err(_) => false
+    }
+}
+
+pub fn iptables_err(e: impl ToString) -> Error {
+    Error::msg(format!("iptables: {}", e.to_string()))
+}
+
+pub fn install_iptables_rules(ipt: &IPTables) -> Result<()> {
+    let q_num = crate::opt::queue_num().to_string();
+    // prevent inf loop
+    let mark = format!("{:#x}", INJECT_MARK);
+
+    let mut rule = vec![
+        "-p", "tcp", "--dport", "443",
+        "-j", "NFQUEUE", "--queue-num", &q_num, "--queue-bypass"
+    ];
+
+    if is_u32_supported(ipt) {
+        const U32: &str = "0>>22&0x3C @ 12>>26&0x3C @ 0>>24&0xFF=0x16 && \
+                           0>>22&0x3C @ 12>>26&0x3C @ 2>>24&0xFF=0x01";
+
+        rule.extend_from_slice(&["-m", "u32", "--u32", U32]);
+    }
+
+    ipt.new_chain("mangle", DPIBREAK_CHAIN).map_err(iptables_err)?;
+
+    ipt.insert(
+        "mangle",
+        DPIBREAK_CHAIN,
+        &["-m", "mark", "--mark", &mark, "-j", "RETURN"],
+        1
+    ).map_err(iptables_err)?;
+
+    ipt.append("mangle", DPIBREAK_CHAIN, &rule).map_err(iptables_err)?;
+    log_println!(LogLevel::Info, "{}: new chain {} on table mangle", ipt.cmd, DPIBREAK_CHAIN);
+
+    ipt.insert("mangle", "POSTROUTING", &["-j", DPIBREAK_CHAIN], 1).map_err(iptables_err)?;
+    log_println!(LogLevel::Info, "{}: add jump to {} chain on POSTROUTING", ipt.cmd, DPIBREAK_CHAIN);
+
+    Ok(())
+}
+
+pub fn cleanup_iptables_rules(ipt: &IPTables) -> Result<()> {
+    if ipt.delete("mangle", "POSTROUTING", &["-j", DPIBREAK_CHAIN]).is_ok() {
+        log_println!(LogLevel::Info, "{}: delete jump to {} from mangle/POSTROUTING", ipt.cmd, DPIBREAK_CHAIN);
+    }
+
+    if ipt.flush_chain("mangle", DPIBREAK_CHAIN).is_ok() {
+        log_println!(LogLevel::Info, "{}: flush chain {}", ipt.cmd, DPIBREAK_CHAIN);
+    }
+
+    if ipt.delete_chain("mangle", DPIBREAK_CHAIN).is_ok() {
+        log_println!(LogLevel::Info, "{}: delete chain {}", ipt.cmd, DPIBREAK_CHAIN);
+    }
+
+    Ok(())
+}
+
+pub fn cleanup_xt_u32() -> Result<()> {
+    if IS_XT_U32_LOADED_BY_US.load(Ordering::Relaxed) {
+        exec_process(&["modprobe", "-q", "-r", "xt_u32"], None)?;
+        log_println!(LogLevel::Info, "cleanup: unload xt_u32");
+    }
+
+    Ok(())
+}