No longer set SIOCGIFFLAGS, update README.md

Kioubit · Jan 7, 2022 · a7eb52c · a7eb52c
1 parent ede44e8
commit a7eb52c
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Showing 3 changed files with 36 additions and 24 deletions.
diff --git a/README.md b/README.md
@@ -10,7 +10,7 @@
 
 ## Installing & Updating
 
-1) Download the latest release from the releases page and move the binary to the ``/usr/local/bin/`` directory under the filename ``pndpd``.
+1) Download the latest release from the [releases page](https://github.com/Kioubit/pndpd/releases) and move the binary to the ``/usr/local/bin/`` directory under the filename ``pndpd``.
 2) Allow executing the file by running ``chmod +x /usr/local/bin/pndpd``
 3) **For systemd users:** Install the service unit file
 ```` 

diff --git a/pndp/interface.go b/pndp/interface.go
@@ -38,34 +38,46 @@ type iflags struct {
 	flags uint16
 }
 
-func setPromisc(fd int, iface string, enable bool) {
+func setPromisc(fd int, iface string, enable bool, withInterfaceFlags bool) {
 	//TODO re-test ALLMULTI
-	var ifl iflags
-	copy(ifl.name[:], []byte(iface))
-	_, _, ep := syscall.Syscall(syscall.SYS_IOCTL, uintptr(fd), syscall.SIOCGIFFLAGS, uintptr(unsafe.Pointer(&ifl)))
-	if ep != 0 {
-		panic(ep)
-	}
 
-	if enable {
-		ifl.flags |= uint16(syscall.IFF_PROMISC)
-	} else {
-		ifl.flags &^= uint16(syscall.IFF_PROMISC)
-	}
+	// -------------------------- Interface flags --------------------------
+	if withInterfaceFlags {
+		tFD, err := syscall.Socket(syscall.AF_INET6, syscall.SOCK_DGRAM, 0)
+		if err != nil {
+			panic(err)
+		}
 
-	_, _, ep = syscall.Syscall(syscall.SYS_IOCTL, uintptr(fd), syscall.SIOCSIFFLAGS, uintptr(unsafe.Pointer(&ifl)))
-	if ep != 0 {
-		panic(ep)
+		var ifl iflags
+		copy(ifl.name[:], []byte(iface))
+		_, _, ep := syscall.Syscall(syscall.SYS_IOCTL, uintptr(tFD), syscall.SIOCGIFFLAGS, uintptr(unsafe.Pointer(&ifl)))
+		if ep != 0 {
+			panic(ep)
+		}
+
+		if enable {
+			ifl.flags |= uint16(syscall.IFF_PROMISC)
+		} else {
+			ifl.flags &^= uint16(syscall.IFF_PROMISC)
+		}
+
+		_, _, ep = syscall.Syscall(syscall.SYS_IOCTL, uintptr(tFD), syscall.SIOCSIFFLAGS, uintptr(unsafe.Pointer(&ifl)))
+		if ep != 0 {
+			panic(ep)
+		}
+
+		_ = syscall.Close(tFD)
 	}
+	// ---------------------------------------------------------------------
 
-	// Also set Sockopt to promisc
-	intf, err := net.InterfaceByName(iface)
+	// -------------------------- Socket Options ---------------------------
+	iFace, err := net.InterfaceByName(iface)
 	if err != nil {
 		panic(err.Error())
 	}
 
-	mreq := unix.PacketMreq{
-		Ifindex: int32(intf.Index),
+	mReq := unix.PacketMreq{
+		Ifindex: int32(iFace.Index),
 		Type:    unix.PACKET_MR_PROMISC,
 	}
 
@@ -76,9 +88,9 @@ func setPromisc(fd int, iface string, enable bool) {
 		opt = unix.PACKET_DROP_MEMBERSHIP
 	}
 
-	err = unix.SetsockoptPacketMreq(fd, unix.SOL_PACKET, opt, &mreq)
+	err = unix.SetsockoptPacketMreq(fd, unix.SOL_PACKET, opt, &mReq)
 	if err != nil {
 		panic(err)
 	}
-
+	// ---------------------------------------------------------------------
 }
diff --git a/pndp/listener.go b/pndp/listener.go
@@ -34,7 +34,7 @@ func listen(iface string, responder chan *ndpRequest, requestType ndpType, stopW
 	}
 	go func() {
 		<-stopChan
-		setPromisc(fd, iface, false)
+		setPromisc(fd, iface, false, false)
 		_ = syscall.Close(fd)
 		stopWG.Done() // syscall.read does not release when the file descriptor is closed
 	}()
@@ -51,7 +51,7 @@ func listen(iface string, responder chan *ndpRequest, requestType ndpType, stopW
 		panic(err.Error())
 	}
 
-	setPromisc(fd, iface, true)
+	setPromisc(fd, iface, true, false)
 
 	var protocolNo uint32
 	if requestType == ndp_SOL {