From df9cadd9389b87632f53129123ab269d939118a1 Mon Sep 17 00:00:00 2001 From: Neil Alexander Date: Thu, 19 Jul 2018 10:01:12 +0100 Subject: [PATCH 1/2] Cap MTU on Linux in TAP mode --- src/yggdrasil/tun_linux.go | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/src/yggdrasil/tun_linux.go b/src/yggdrasil/tun_linux.go index 24c5aa92..14c2f0a3 100644 --- a/src/yggdrasil/tun_linux.go +++ b/src/yggdrasil/tun_linux.go @@ -29,6 +29,14 @@ func (tun *tunDevice) setup(ifname string, iftapmode bool, addr string, mtu int) } tun.iface = iface tun.mtu = getSupportedMTU(mtu) + // The following check is specific to Linux, as the TAP driver only supports + // an MTU of 65535-14 to make room for the ethernet headers. This makes sure + // that the MTU gets rounded down to 65521 instead of causing a panic. + if iftapmode { + if tun.mtu > 65535-tun_ETHER_HEADER_LENGTH { + tun.mtu = 65535-tun_ETHER_HEADER_LENGTH + } + } return tun.setupAddress(addr) } From 55b56e8686473b7070fd0b72782fbf908e755407 Mon Sep 17 00:00:00 2001 From: Neil Alexander Date: Thu, 19 Jul 2018 10:15:26 +0100 Subject: [PATCH 2/2] Normalise startup output for TUN/TAP on Linux and Windows --- src/yggdrasil/tun_linux.go | 4 ++++ src/yggdrasil/tun_windows.go | 4 ++++ 2 files changed, 8 insertions(+) diff --git a/src/yggdrasil/tun_linux.go b/src/yggdrasil/tun_linux.go index 14c2f0a3..a1f8abdf 100644 --- a/src/yggdrasil/tun_linux.go +++ b/src/yggdrasil/tun_linux.go @@ -37,6 +37,10 @@ func (tun *tunDevice) setup(ifname string, iftapmode bool, addr string, mtu int) tun.mtu = 65535-tun_ETHER_HEADER_LENGTH } } + // Friendly output + tun.core.log.Printf("Interface name: %s", tun.iface.Name()) + tun.core.log.Printf("Interface IPv6: %s", addr) + tun.core.log.Printf("Interface MTU: %d", tun.mtu) return tun.setupAddress(addr) } diff --git a/src/yggdrasil/tun_windows.go b/src/yggdrasil/tun_windows.go index c6e57705..d3420df8 100644 --- a/src/yggdrasil/tun_windows.go +++ b/src/yggdrasil/tun_windows.go @@ -57,6 +57,10 @@ func (tun *tunDevice) setup(ifname string, iftapmode bool, addr string, mtu int) if err != nil { panic(err) } + // Friendly output + tun.core.log.Printf("Interface name: %s", tun.iface.Name()) + tun.core.log.Printf("Interface IPv6: %s", addr) + tun.core.log.Printf("Interface MTU: %d", tun.mtu) return tun.setupAddress(addr) }