From 332a3a1cd09f47458d4cc465b1afe9a430660d64 Mon Sep 17 00:00:00 2001
From: ginuerzh <ginuerzh@gmail.com>
Date: Fri, 26 Apr 2024 20:56:56 +0800
Subject: [PATCH] add p2p option for tun handler

---
 handler/tun/handler.go  | 18 ------------------
 handler/tun/metadata.go | 17 ++++++-----------
 handler/tun/server.go   | 36 ++++++++++++++++++++++++++++++++----
 3 files changed, 38 insertions(+), 33 deletions(-)

diff --git a/handler/tun/handler.go b/handler/tun/handler.go
index 445190e..2f87ffb 100644
--- a/handler/tun/handler.go
+++ b/handler/tun/handler.go
@@ -12,7 +12,6 @@ import (
 	"github.com/go-gost/core/handler"
 	"github.com/go-gost/core/hop"
 	md "github.com/go-gost/core/metadata"
-	"github.com/go-gost/core/router"
 	tun_util "github.com/go-gost/x/internal/util/tun"
 	"github.com/go-gost/x/registry"
 	"github.com/songgao/water/waterutil"
@@ -109,23 +108,6 @@ func (h *tunHandler) Handle(ctx context.Context, conn net.Conn, opts ...handler.
 	return h.handleServer(ctx, conn, config, log)
 }
 
-func (h *tunHandler) findRouteFor(ctx context.Context, dst net.IP, router router.Router) net.Addr {
-	if v, ok := h.routes.Load(ipToTunRouteKey(dst)); ok {
-		return v.(net.Addr)
-	}
-
-	if router == nil {
-		return nil
-	}
-
-	if route := router.GetRoute(ctx, dst); route != nil && route.Gateway != nil {
-		if v, ok := h.routes.Load(ipToTunRouteKey(route.Gateway)); ok {
-			return v.(net.Addr)
-		}
-	}
-	return nil
-}
-
 var mIPProts = map[waterutil.IPProtocol]string{
 	waterutil.HOPOPT:     "HOPOPT",
 	waterutil.ICMP:       "ICMP",
diff --git a/handler/tun/metadata.go b/handler/tun/metadata.go
index 5abb881..0c173eb 100644
--- a/handler/tun/metadata.go
+++ b/handler/tun/metadata.go
@@ -16,28 +16,23 @@ type metadata struct {
 	bufferSize      int
 	keepAlivePeriod time.Duration
 	passphrase      string
+	p2p             bool
 }
 
 func (h *tunHandler) parseMetadata(md mdata.Metadata) (err error) {
-	const (
-		bufferSize      = "bufferSize"
-		keepAlive       = "keepAlive"
-		keepAlivePeriod = "ttl"
-		passphrase      = "passphrase"
-	)
-
-	h.md.bufferSize = mdutil.GetInt(md, bufferSize)
+	h.md.bufferSize = mdutil.GetInt(md, "tun.bufsize", "bufsize", "buffersize")
 	if h.md.bufferSize <= 0 {
 		h.md.bufferSize = defaultBufferSize
 	}
 
-	if mdutil.GetBool(md, keepAlive) {
-		h.md.keepAlivePeriod = mdutil.GetDuration(md, keepAlivePeriod)
+	if mdutil.GetBool(md, "tun.keepalive", "keepalive") {
+		h.md.keepAlivePeriod = mdutil.GetDuration(md, "tun.ttl", "ttl")
 		if h.md.keepAlivePeriod <= 0 {
 			h.md.keepAlivePeriod = defaultKeepAlivePeriod
 		}
 	}
 
-	h.md.passphrase = mdutil.GetString(md, passphrase)
+	h.md.passphrase = mdutil.GetString(md, "tun.token", "token", "passphrase")
+	h.md.p2p = mdutil.GetBool(md, "tun.p2p", "p2p")
 	return
 }
diff --git a/handler/tun/server.go b/handler/tun/server.go
index 64c9b8e..ad22d20 100644
--- a/handler/tun/server.go
+++ b/handler/tun/server.go
@@ -10,6 +10,7 @@ import (
 
 	"github.com/go-gost/core/common/bufpool"
 	"github.com/go-gost/core/logger"
+	"github.com/go-gost/core/router"
 	tun_util "github.com/go-gost/x/internal/util/tun"
 	"github.com/songgao/water/waterutil"
 	"golang.org/x/net/ipv4"
@@ -203,11 +204,13 @@ func (h *tunHandler) transportServer(ctx context.Context, tun io.ReadWriter, con
 					return nil
 				}
 
-				if addr := h.findRouteFor(ctx, dst, config.Router); addr != nil {
-					log.Debugf("find route: %s -> %s", dst, addr)
+				if !h.md.p2p {
+					if addr := h.findRouteFor(ctx, dst, config.Router); addr != nil {
+						log.Debugf("find route: %s -> %s", dst, addr)
 
-					_, err := conn.WriteTo(b[:n], addr)
-					return err
+						_, err := conn.WriteTo(b[:n], addr)
+						return err
+					}
 				}
 
 				if _, err := tun.Write(b[:n]); err != nil {
@@ -231,6 +234,9 @@ func (h *tunHandler) transportServer(ctx context.Context, tun io.ReadWriter, con
 }
 
 func (h *tunHandler) updateRoute(ip net.IP, addr net.Addr, log logger.Logger) {
+	if h.md.p2p {
+		ip = net.IPv6zero
+	}
 	rkey := ipToTunRouteKey(ip)
 	if actual, loaded := h.routes.LoadOrStore(rkey, addr); loaded {
 		if actual.(net.Addr).String() != addr.String() {
@@ -242,3 +248,25 @@ func (h *tunHandler) updateRoute(ip net.IP, addr net.Addr, log logger.Logger) {
 		log.Debugf("new route: %s -> %s", ip, addr)
 	}
 }
+
+func (h *tunHandler) findRouteFor(ctx context.Context, dst net.IP, router router.Router) net.Addr {
+	if h.md.p2p {
+		dst = net.IPv6zero
+		router = nil
+	}
+
+	if v, ok := h.routes.Load(ipToTunRouteKey(dst)); ok {
+		return v.(net.Addr)
+	}
+
+	if router == nil {
+		return nil
+	}
+
+	if route := router.GetRoute(ctx, dst); route != nil && route.Gateway != nil {
+		if v, ok := h.routes.Load(ipToTunRouteKey(route.Gateway)); ok {
+			return v.(net.Addr)
+		}
+	}
+	return nil
+}