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// Package wireguard implements a few helpers for the WireGuard protocol
package wireguard
import (
"errors"
"fmt"
"net"
"github.com/eduvpn/eduvpn-common/internal/wireguard/ini"
"golang.zx2c4.com/wireguard/wgctrl/wgtypes"
)
func availableTCPPort() (int, error) {
tcpaddr, err := net.ResolveTCPAddr("tcp", "127.0.0.1:0")
if err != nil {
return -1, err
}
ltcp, err := net.ListenTCP("tcp", tcpaddr)
if err != nil {
return -1, err
}
defer ltcp.Close()
return ltcp.Addr().(*net.TCPAddr).Port, nil
}
func availableUDPPort() (int, error) {
udpaddr, err := net.ResolveUDPAddr("udp", "127.0.0.1:0")
if err != nil {
return -1, err
}
ludp, err := net.ListenUDP("udp", udpaddr)
if err != nil {
return -1, err
}
defer ludp.Close()
return ludp.LocalAddr().(*net.UDPAddr).Port, nil
}
type Proxy struct {
SourcePort int
Listen string
Peer string
}
func Config(cfg string, key *wgtypes.Key, tcp bool) (string, *Proxy, error) {
// the key is nil if the client does not accept WireGuard
if key == nil {
return "", nil, errors.New("the server sent us a WireGuard profile but the client does not accept WireGuard")
}
var tcpp int
var proxy string
var err error
if tcp {
tcpp, err = availableTCPPort()
if err != nil {
return "", nil, err
}
udpp, err := availableUDPPort()
if err != nil {
return "", nil, err
}
proxy = fmt.Sprintf("127.0.0.1:%d", udpp)
}
rcfg, peer, err := configReplace(cfg, *key, proxy)
if err != nil {
return "", nil, err
}
var retP *Proxy
if tcp {
retP = &Proxy{
SourcePort: tcpp,
Listen: proxy,
Peer: peer,
}
}
return rcfg, retP, nil
}
// ConfigReplace replaces the wireguard config with our private key and proxy in case of TCP
func configReplace(cfg string, key wgtypes.Key, proxy string) (string, string, error) {
// first parse the config
secs := ini.Parse(cfg)
if secs.Empty() {
return "", "", errors.New("parsed ini is empty")
}
// find the interface section
// and set the private key
is, err := secs.Section("Interface")
if err != nil {
return "", "", err
}
is.AddOrReplaceKeyValue("PrivateKey", key.String())
peer := ""
if proxy != "" {
ps, err := secs.Section("Peer")
if err != nil {
return "", "", err
}
peer, err = ps.RemoveKey("TCPEndpoint")
if err != nil {
return "", "", err
}
ps.AddOrReplaceKeyValue("Endpoint", proxy)
}
return secs.String(), peer, nil
}
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