Configure MTU on per-user basis

[govpn.git] / src / govpn / tap.go

diff --git a/src/govpn/tap.go b/src/govpn/tap.go
index c5e3bf835cfee5f993f4eeff946c035bd005617e..6e545b4decfeae9262a73f82e00348e60c89c609 100644 (file)
--- a/src/govpn/tap.go
+++ b/src/govpn/tap.go
@@ -1,6 +1,6 @@
 /*
 GoVPN -- simple secure free software virtual private network daemon
-Copyright (C) 2014-2015 Sergey Matveev <stargrave@stargrave.org>
+Copyright (C) 2014-2016 Sergey Matveev <stargrave@stargrave.org>
 
 This program is free software: you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
@@ -20,53 +20,49 @@ package govpn
 
 import (
        "io"
-
-       "golang.org/x/crypto/poly1305"
-)
-
-const (
-       EtherSize = 14
 )
 
 type TAP struct {
-       Name   string
-       dev    io.ReadWriter
-       buf    []byte
-       sink   chan []byte
-       ready  chan struct{}
-       synced bool
+       Name string
+       Sink chan []byte
+       dev  io.ReadWriter
+       buf0 []byte
+       buf1 []byte
+       bufZ bool
 }
 
-// Return maximal acceptable TAP interface MTU. This is daemon's MTU
-// minus nonce, MAC, packet size mark and Ethernet header sizes.
-func TAPMaxMTU() int {
-       return MTU - poly1305.TagSize - NonceSize - PktSizeSize - EtherSize
-}
+var (
+       taps = make(map[string]*TAP)
+)
 
-func NewTAP(ifaceName string) (*TAP, error) {
-       maxIfacePktSize := TAPMaxMTU() + EtherSize
+func NewTAP(ifaceName string, mtu int) (*TAP, error) {
        tapRaw, err := newTAPer(ifaceName)
        if err != nil {
                return nil, err
        }
        tap := TAP{
-               Name:   ifaceName,
-               dev:    tapRaw,
-               buf:    make([]byte, maxIfacePktSize),
-               sink:   make(chan []byte),
-               ready:  make(chan struct{}),
-               synced: false,
+               Name: ifaceName,
+               dev:  tapRaw,
+               buf0: make([]byte, mtu),
+               buf1: make([]byte, mtu),
+               Sink: make(chan []byte),
        }
        go func() {
                var n int
                var err error
+               var buf []byte
                for {
-                       <-tap.ready
-                       n, err = tap.dev.Read(tap.buf)
+                       if tap.bufZ {
+                               buf = tap.buf0
+                       } else {
+                               buf = tap.buf1
+                       }
+                       tap.bufZ = !tap.bufZ
+                       n, err = tap.dev.Read(buf)
                        if err != nil {
                                panic("Reading TAP:" + err.Error())
                        }
-                       tap.sink <- tap.buf[:n]
+                       tap.Sink <- buf[:n]
                }
        }()
        return &tap, nil
@@ -75,3 +71,16 @@ func NewTAP(ifaceName string) (*TAP, error) {
 func (t *TAP) Write(data []byte) (n int, err error) {
        return t.dev.Write(data)
 }
+
+func TAPListen(ifaceName string, mtu int) (*TAP, error) {
+       tap, exists := taps[ifaceName]
+       if exists {
+               return tap, nil
+       }
+       tap, err := NewTAP(ifaceName, mtu)
+       if err != nil {
+               return nil, err
+       }
+       taps[ifaceName] = tap
+       return tap, nil
+}