u32

src/config.rs

@@ -11,8 +11,8 @@ pub struct Config {
 }
 #[derive(Deserialize, Clone)]
 pub struct ConfigRouter {
-    pub local_id: u8,
-    pub remote_id: u8,
+    pub local_id: u32,
+    pub remote_id: u32,
     #[serde(default)]
     pub schema: Schema,
     #[serde(default)]

src/main.rs

@@ -42,7 +42,7 @@ fn main() -> Result<()> {
         .into_iter()
         .sorted_by_key(|r| r.remote_id)
         .map(|c| Router::new(c).map(|router| (router.config.remote_id, router)))
-        .collect::<Result<BTreeMap<u8, Router>, _>>()?;
+        .collect::<Result<BTreeMap<u32, Router>, _>>()?;
 
     for (_, group) in &routers
         .values()
@@ -99,8 +99,7 @@ fn main() -> Result<()> {
                         let mut meta_bytes = [MaybeUninit::uninit(); META_SIZE];
                         Router::recv_exact_tcp(&connection, &mut meta_bytes).unwrap();
                         let meta: &Meta = Meta::from_bytes(&meta_bytes);
-                        if meta.reversed == 0
-                            && let Some(router) = routers.get(&meta.src_id)
+                        if let Some(router) = routers.get(&meta.src_id)
                             && meta.dst_id == router.config.local_id
                         {
                             // let connection = Arc::new(connection);

src/router.rs

@@ -15,7 +15,7 @@ use tun::Device;
 use crate::config::{ConfigRouter, Schema};
 use crossbeam::epoch::{pin, Atomic};
 use libc::{
-    setsockopt, sock_filter, sock_fprog, socklen_t, BPF_ABS, BPF_B, BPF_IND, BPF_JEQ, BPF_JMP, BPF_K, BPF_LD, BPF_LDX, BPF_MSH, BPF_RET, BPF_W,
+    setsockopt, sock_filter, sock_fprog, socklen_t, BPF_ABS, BPF_B, BPF_IND, BPF_JEQ, BPF_JMP, BPF_K, BPF_LD, BPF_LDX, BPF_MEM, BPF_MSH, BPF_RET, BPF_ST, BPF_W,
     MSG_FASTOPEN, SOL_SOCKET, SO_ATTACH_REUSEPORT_CBPF,
 };
 
@@ -25,9 +25,8 @@ pub const META_SIZE: usize = size_of::<Meta>();
 #[repr(C)]
 #[derive(Debug, Clone, Copy, Default)]
 pub struct Meta {
-    pub src_id: u8,
-    pub dst_id: u8,
-    pub reversed: u16,
+    pub src_id: u32,
+    pub dst_id: u32,
 }
 impl Meta {
     pub fn as_bytes(&self) -> &[u8; META_SIZE] {
@@ -119,7 +118,6 @@ impl Router {
         let meta = Meta {
             src_id: self.config.local_id,
             dst_id: self.config.remote_id,
-            reversed: 0,
         };
         let guard = pin();
         let endpoint_ref = self.endpoint.load(Ordering::Relaxed, &guard);
@@ -130,44 +128,54 @@ impl Router {
     }
 
     fn attach_filter_ip(config: &ConfigRouter, socket: &Socket) -> Result<()> {
-        // 由于多个对端可能会使用相同的 ipprpto 号，这里确保每个 socket 上只会收到自己对应的对端发来的消息
-        let meta = Meta {
-            src_id: config.remote_id,
-            dst_id: config.local_id,
-            reversed: 0,
-        };
-        let value = u32::from_be_bytes(*meta.as_bytes());
-
-        // 如果你的协议是 UDP，这里必须是 8 (跳过 UDP 头: SrcPort(2)+DstPort(2)+Len(2)+Sum(2))
-        // 如果是纯自定义 IP 协议，这里是 0
-        let payload_offset = 0;
+        // 由于多个对端可能会使用相同的 ipproto 号，这里确保每个 socket 上只会收到自己对应的对端发来的消息
+        
+        // 构造 Meta 来计算正确的字节序比较值
+        let meta_bytes = [
+            config.remote_id.to_le_bytes(),
+            config.local_id.to_le_bytes(),
+        ];
+        
+        // BPF 按网络字节序（大端序）比较，所以需要把小端序字节当作大端序来构造比较值
+        let expected_src_id = u32::from_be_bytes(meta_bytes[0]);
+        let expected_dst_id = u32::from_be_bytes(meta_bytes[1]);
 
         // IP filter 工作原理：
         // 每个对端起一个 raw socket
         // 根据报文内容判断是给谁的。拒绝掉不是给自己的报文
         // IPv4 raw socket 带 IP 头，IPv6 不带
+        // Meta 结构：src_id(u32) + dst_id(u32) = 8 字节
 
         let filters: &[SockFilter] = match socket.domain()? {
             Domain::IPV4 => &[
                 // [IPv4] 计算 IPv4 头长度: X = 4 * (IP[0] & 0xf)
                 bpf_stmt(BPF_LDX | BPF_B | BPF_MSH, 0),
-                // A = Packet[X + payload_offset]
-                bpf_stmt(BPF_LD | BPF_W | BPF_IND, payload_offset),
-                // if (A == target_val) goto Accept; else goto Reject;
-                bpf_jump(BPF_JMP | BPF_JEQ | BPF_K, value, 0, 1),
-                // 【接受 (True 路径)】
+                // A = Packet[X + 0:4] = src_id
+                bpf_stmt(BPF_LD | BPF_W | BPF_IND, 0),
+                // if A != expected_src_id, goto reject
+                bpf_jump(BPF_JMP | BPF_JEQ | BPF_K, expected_src_id, 0, 3),
+                // A = Packet[X + 4:8] = dst_id
+                bpf_stmt(BPF_LD | BPF_W | BPF_IND, 4),
+                // if A != expected_dst_id, goto reject
+                bpf_jump(BPF_JMP | BPF_JEQ | BPF_K, expected_dst_id, 0, 1),
+                // 【接受】
                 bpf_stmt(BPF_RET | BPF_K, u32::MAX),
-                // 【拒绝 (False 路径)】
+                // 【拒绝】
                 bpf_stmt(BPF_RET | BPF_K, 0),
             ],
             Domain::IPV6 => &[
-                // raw socket IPv6 没有 header，加载第 0 字节到累加器 A
+                // raw socket IPv6 没有 header
+                // A = Packet[0:4] = src_id
                 bpf_stmt(BPF_LD | BPF_W | BPF_ABS, 0),
-                // if (A == target_val) goto Accept; else goto Reject;
-                bpf_jump(BPF_JMP | BPF_JEQ | BPF_K, value, 0, 1),
-                // 【接受 (True 路径)】
+                // if A != expected_src_id, goto reject
+                bpf_jump(BPF_JMP | BPF_JEQ | BPF_K, expected_src_id, 0, 3),
+                // A = Packet[4:8] = dst_id
+                bpf_stmt(BPF_LD | BPF_W | BPF_ABS, 4),
+                // if A != expected_dst_id, goto reject
+                bpf_jump(BPF_JMP | BPF_JEQ | BPF_K, expected_dst_id, 0, 1),
+                // 【接受】
                 bpf_stmt(BPF_RET | BPF_K, u32::MAX),
-                // 【拒绝 (False 路径)】
+                // 【拒绝】
                 bpf_stmt(BPF_RET | BPF_K, 0),
             ],
             _ => bail!("unsupported family"),
@@ -178,33 +186,44 @@ impl Router {
     }
 
     pub fn attach_filter_udp(group: Vec<&Router>) -> Result<()> {
-        let values: Vec<u32> = group
-            .iter()
-            .map(|&f| {
-                let meta = Meta {
-                    src_id: f.config.remote_id,
-                    dst_id: f.config.local_id,
-                    reversed: 0,
-                };
-                u32::from_be_bytes(*meta.as_bytes())
-            })
-            .collect();
-
-        let mut filters: Vec<SockFilter> = Vec::with_capacity(1 + values.len() * 2 + 1);
+        // 预留空间：4 条前置指令 + 每个 router 5 条 + 1 条默认返回
+        let mut filters: Vec<SockFilter> = Vec::with_capacity(4 + group.len() * 5 + 1);
 
         // udp filter 工作原理：
         // 每个对端起一个 udp socket
         // 根据报文内容判断是给谁的，调度给对应的端口复用组序号
-
-        // Load the first 4 bytes of the packet into the accumulator (A)
-        filters.push(bpf_stmt(BPF_LD | BPF_W | BPF_ABS, 0));
-        for (i, &val) in values.iter().enumerate() {
-            // 如果匹配，继续下一句(返回)，如果不匹配，跳过下一句。
-            filters.push(bpf_jump(BPF_JMP | BPF_JEQ | BPF_K, val, 0, 1));
-            // If match, return the index (i + 1, since 0 means drop)
+        // Meta 结构：src_id(u32) + dst_id(u32) = 8 字节
+
+        // 加载 src_id 并存储到 M[0]
+        filters.push(bpf_stmt(BPF_LD | BPF_W | BPF_ABS, 0));  // A = packet[0:4] = src_id
+        filters.push(bpf_stmt(BPF_ST, 0));                    // M[0] = A
+
+        // 加载 dst_id 并存储到 M[1]
+        filters.push(bpf_stmt(BPF_LD | BPF_W | BPF_ABS, 4));  // A = packet[4:8] = dst_id
+        filters.push(bpf_stmt(BPF_ST, 1));                    // M[1] = A
+
+        for (i, router) in group.iter().enumerate() {
+            // 字节序转换：将小端序ID转换为BPF期望的大端序比较值
+            let src_bytes = router.config.remote_id.to_le_bytes();
+            let dst_bytes = router.config.local_id.to_le_bytes();
+            let expected_src_id = u32::from_be_bytes(src_bytes);
+            let expected_dst_id = u32::from_be_bytes(dst_bytes);
+
+            // 每个 router 5 条指令：
+            // 0: LD M[0]                      ; A = src_id
+            // 1: JEQ expected_src_id, +0, +3  ; 匹配继续，不匹配跳过当前 router
+            // 2: LD M[1]                      ; A = dst_id
+            // 3: JEQ expected_dst_id, +0, +1  ; 匹配继续，不匹配跳过当前 router
+            // 4: RET i                        ; 返回索引
+
+            filters.push(bpf_stmt(BPF_LD | BPF_MEM, 0));
+            filters.push(bpf_jump(BPF_JMP | BPF_JEQ | BPF_K, expected_src_id, 0, 3));
+            filters.push(bpf_stmt(BPF_LD | BPF_MEM, 1));
+            filters.push(bpf_jump(BPF_JMP | BPF_JEQ | BPF_K, expected_dst_id, 0, 1));
             filters.push(bpf_stmt(BPF_RET | BPF_K, i as u32));
         }
-        // If no match found after all comparisons, drop the packet
+
+        // 默认返回（不匹配任何 router）
         filters.push(bpf_stmt(BPF_RET | BPF_K, u32::MAX));
 
         let prog = sock_fprog {
@@ -232,7 +251,6 @@ impl Router {
         let meta = Meta {
             src_id: self.config.local_id,
             dst_id: self.config.remote_id,
-            reversed: 0,
         };
         buffer[..META_SIZE].copy_from_slice(meta.as_bytes());