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tunnel.go
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tunnel.go
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package wg
import (
"bufio"
"bytes"
"context"
"fmt"
"math/rand"
"net"
"net/netip"
"github.com/miekg/dns"
"golang.zx2c4.com/wireguard/conn"
"golang.zx2c4.com/wireguard/device"
"golang.zx2c4.com/wireguard/tun"
"golang.zx2c4.com/wireguard/tun/netstack"
)
type Tunnel struct {
dev *device.Device
tun tun.Device
net *netstack.Net
dnsIP net.IP
State *WireGuardState
Config *Config
wscancel func()
resolv *net.Resolver
}
func Connect(ctx context.Context, state *WireGuardState) (*Tunnel, error) {
return doConnect(ctx, state, false)
}
func doConnect(ctx context.Context, state *WireGuardState, wswg bool) (*Tunnel, error) {
cfg := state.TunnelConfig()
fmt.Println("wg connect", cfg.DNS, cfg.Endpoint, cfg.LocalNetwork.IP, cfg.RemoteNetwork.IP)
addr, ok := netip.AddrFromSlice(cfg.LocalNetwork.IP)
if !ok {
return nil, fmt.Errorf("could not generate local network addr from IP %s: ", cfg.LocalNetwork.IP)
}
localIPs := []netip.Addr{addr}
dnsIP, ok := netip.AddrFromSlice(cfg.DNS)
if !ok {
return nil, fmt.Errorf("could not generate DNS addr from IP %s: ", cfg.DNS)
}
mtu := cfg.MTU
if mtu == 0 {
mtu = device.DefaultMTU
}
tunDev, gNet, err := netstack.CreateNetTUN(localIPs, []netip.Addr{dnsIP}, mtu)
if err != nil {
return nil, err
}
endpointHost, endpointPort, err := net.SplitHostPort(cfg.Endpoint)
if err != nil {
return nil, err
}
endpointIPs, err := net.LookupIP(endpointHost)
if err != nil {
return nil, err
}
endpointIP := endpointIPs[rand.Intn(len(endpointIPs))]
endpointAddr := net.JoinHostPort(endpointIP.String(), endpointPort)
if wswg {
port, err := websocketConnect(ctx, endpointHost)
if err != nil {
return nil, err
}
endpointAddr = fmt.Sprintf("127.0.0.1:%d", port)
}
wgDev := device.NewDevice(tunDev, conn.NewDefaultBind(), device.NewLogger(cfg.LogLevel, "(fly-ssh) "))
wgConf := bytes.NewBuffer(nil)
fmt.Fprintf(wgConf, "private_key=%s\n", cfg.LocalPrivateKey.ToHex())
fmt.Fprintf(wgConf, "public_key=%s\n", cfg.RemotePublicKey.ToHex())
fmt.Fprintf(wgConf, "endpoint=%s\n", endpointAddr)
fmt.Fprintf(wgConf, "allowed_ip=%s\n", cfg.RemoteNetwork)
fmt.Fprintf(wgConf, "persistent_keepalive_interval=%d\n", cfg.KeepAlive)
if err := wgDev.IpcSetOperation(bufio.NewReader(wgConf)); err != nil {
return nil, err
}
wgDev.Up()
return &Tunnel{
dev: wgDev,
tun: tunDev,
net: gNet,
dnsIP: cfg.DNS,
Config: cfg,
State: state,
resolv: &net.Resolver{
PreferGo: true,
Dial: func(ctx context.Context, network, address string) (net.Conn, error) {
fmt.Println("resolver.Dial", network, address)
return gNet.DialContext(ctx, "tcp", net.JoinHostPort(dnsIP.String(), "53"))
},
},
}, nil
}
func (t *Tunnel) Close() error {
if t.wscancel != nil {
t.wscancel()
t.wscancel = nil
}
if t.dev != nil {
t.dev.Close()
}
t.dev, t.net, t.tun = nil, nil, nil
return nil
}
func (t *Tunnel) DialContext(ctx context.Context, network, addr string) (net.Conn, error) {
return t.net.DialContext(ctx, network, addr)
}
func (t *Tunnel) Resolver() *net.Resolver {
return t.resolv
}
func (t *Tunnel) LookupTXT(ctx context.Context, name string) ([]string, error) {
var m dns.Msg
_ = m.SetQuestion(dns.Fqdn(name), dns.TypeTXT)
r, err := t.queryDNS(ctx, &m)
if err != nil {
return nil, err
}
results := make([]string, 0, len(r.Answer))
for _, a := range r.Answer {
txt := a.(*dns.TXT)
results = append(results, txt.Txt...)
}
return results, nil
}
func (t *Tunnel) ListenPing() (*netstack.PingConn, error) {
laddr, ok := netip.AddrFromSlice(t.Config.LocalNetwork.IP)
if !ok {
return nil, fmt.Errorf("could not generate local network addr from IP %s: ", t.Config.LocalNetwork.IP)
}
raddr := netip.IPv6Unspecified()
conn, err := t.net.DialPingAddr(laddr, raddr)
if err != nil {
return nil, fmt.Errorf("ping listener: %w", err)
}
return conn, nil
}
func (t *Tunnel) LookupAAAA(ctx context.Context, name string) ([]net.IP, error) {
var m dns.Msg
_ = m.SetQuestion(dns.Fqdn(name), dns.TypeAAAA)
r, err := t.queryDNS(ctx, &m)
if err != nil {
return nil, err
}
results := make([]net.IP, 0, len(r.Answer))
for _, a := range r.Answer {
ip := a.(*dns.AAAA).AAAA
results = append(results, ip)
}
return results, nil
}
func (t *Tunnel) queryDNS(ctx context.Context, msg *dns.Msg) (*dns.Msg, error) {
client := dns.Client{
Net: "tcp",
Dialer: &net.Dialer{
Resolver: t.resolv,
},
}
c, err := t.DialContext(ctx, "tcp", net.JoinHostPort(t.dnsIP.String(), "53"))
if err != nil {
return nil, err
}
defer c.Close()
conn := &dns.Conn{Conn: c}
defer conn.Close()
r, _, err := client.ExchangeWithConn(msg, conn)
return r, err
}