2 GoVPN -- simple secure free software virtual private network daemon
3 Copyright (C) 2014-2015 Sergey Matveev <stargrave@stargrave.org>
5 This program is free software: you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation, either version 3 of the License, or
8 (at your option) any later version.
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
15 You should have received a copy of the GNU General Public License
16 along with this program. If not, see <http://www.gnu.org/licenses/>.
24 "golang.org/x/crypto/poly1305"
40 // Return maximal acceptable TAP interface MTU. This is daemon's MTU
41 // minus nonce, MAC, packet size mark and Ethernet header sizes.
42 func TAPMaxMTU() int {
43 return MTU - poly1305.TagSize - NonceSize - PktSizeSize - EtherSize
46 func NewTAP(ifaceName string) (*TAP, error) {
47 maxIfacePktSize := TAPMaxMTU() + EtherSize
48 tapRaw, err := newTAPer(ifaceName)
55 buf: make([]byte, maxIfacePktSize),
56 sink: make(chan []byte),
57 ready: make(chan struct{}),
65 n, err = tap.dev.Read(tap.buf)
69 tap.sink <- tap.buf[:n]
75 func (t *TAP) Write(data []byte) (n int, err error) {
76 return t.dev.Write(data)