Outbound: Fix sendthrough srcip precheck (#4750)

Co-authored-by: RPRX <[email protected]>

app/proxyman/outbound/handler.go

@@ -279,11 +279,9 @@ func (h *Handler) Dial(ctx context.Context, dest net.Destination) (stat.Connecti
 
 			outbounds := session.OutboundsFromContext(ctx)
 			ob := outbounds[len(outbounds)-1]
-			addr := h.senderSettings.Via.AsAddress()
 			var domain string
-			if addr.Family().IsDomain() {
-				domain = addr.Domain()
-			}
+			addr := h.senderSettings.Via.AsAddress()
+			domain = h.senderSettings.Via.GetDomain()
 			switch {
 			case h.senderSettings.ViaCidr != "":
 				ob.Gateway = ParseRandomIP(addr, h.senderSettings.ViaCidr)
@@ -291,18 +289,24 @@ func (h *Handler) Dial(ctx context.Context, dest net.Destination) (stat.Connecti
 			case domain == "origin":
 
 				if inbound := session.InboundFromContext(ctx); inbound != nil {
-					origin, _, err := net.SplitHostPort(inbound.Conn.LocalAddr().String())
-					if err == nil {
-						ob.Gateway = net.ParseAddress(origin)
+					if inbound.Conn != nil {
+						origin, _, err := net.SplitHostPort(inbound.Conn.LocalAddr().String())
+						if err == nil {
+							ob.Gateway = net.ParseAddress(origin)
+							errors.LogDebug(ctx, "use receive package ip as snedthrough: ", origin)
+						}
 					}
-
 				}
 			case domain == "srcip":
 				if inbound := session.InboundFromContext(ctx); inbound != nil {
-					srcip, _, err := net.SplitHostPort(inbound.Conn.RemoteAddr().String())
-					if err == nil {
-						ob.Gateway = net.ParseAddress(srcip)
+					if inbound.Conn != nil {
+						clientaddr, _, err := net.SplitHostPort(inbound.Conn.RemoteAddr().String())
+						if err == nil {
+							ob.Gateway = net.ParseAddress(clientaddr)
+							errors.LogDebug(ctx, "use client src ip as snedthrough: ", clientaddr)
+						}
 					}
+
 				}
 			//case addr.Family().IsDomain():
 			default:

infra/conf/xray.go

@@ -292,7 +292,8 @@ func (c *OutboundDetourConfig) Build() (*core.OutboundHandlerConfig, error) {
 			senderSettings.ViaCidr = strings.Split(*c.SendThrough, "/")[1]
 		} else {
 			if address.Family().IsDomain() {
-				if address.Address.Domain() != "origin" {
+				domain := address.Address.Domain()
+				if domain != "origin" && domain != "srcip" {
 					return nil, errors.New("unable to send through: " + address.String())
 				}
 			}