yggdrasil-go/src/yggdrasil/tun_linux.go

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// +build !mobile
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package yggdrasil
// The linux platform specific tun parts
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import (
"errors"
"fmt"
"net"
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"github.com/docker/libcontainer/netlink"
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water "github.com/yggdrasil-network/water"
)
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// Configures the TAP adapter with the correct IPv6 address and MTU.
func (tun *tunAdapter) setup(ifname string, iftapmode bool, addr string, mtu int) error {
var config water.Config
if iftapmode {
config = water.Config{DeviceType: water.TAP}
} else {
config = water.Config{DeviceType: water.TUN}
}
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if ifname != "" && ifname != "auto" {
config.Name = ifname
}
iface, err := water.New(config)
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if err != nil {
panic(err)
}
tun.iface = iface
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tun.mtu = getSupportedMTU(mtu)
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// 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 {
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tun.mtu = 65535 - tun_ETHER_HEADER_LENGTH
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}
}
// 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)
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return tun.setupAddress(addr)
}
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// Configures the TAP adapter with the correct IPv6 address and MTU. Netlink
// is used to do this, so there is not a hard requirement on "ip" or "ifconfig"
// to exist on the system, but this will fail if Netlink is not present in the
// kernel (it nearly always is).
func (tun *tunAdapter) setupAddress(addr string) error {
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// Set address
var netIF *net.Interface
ifces, err := net.Interfaces()
if err != nil {
return err
}
for _, ifce := range ifces {
if ifce.Name == tun.iface.Name() {
var newIF = ifce
netIF = &newIF // Don't point inside ifces, it's apparently unsafe?...
}
}
if netIF == nil {
return errors.New(fmt.Sprintf("Failed to find interface: %s", tun.iface.Name()))
}
ip, ipNet, err := net.ParseCIDR(addr)
if err != nil {
return err
}
err = netlink.NetworkLinkAddIp(netIF, ip, ipNet)
if err != nil {
return err
}
err = netlink.NetworkSetMTU(netIF, tun.mtu)
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if err != nil {
return err
}
netlink.NetworkLinkUp(netIF)
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if err != nil {
return err
}
return nil
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}