/
main.go
284 lines (255 loc) · 8.21 KB
/
main.go
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package main
import (
"context"
"encoding/base64"
"errors"
"fmt"
"io/ioutil"
"net"
"os"
"os/exec"
"strconv"
"time"
"github.com/digitalocean/godo"
"github.com/vishvananda/netlink"
"go.uber.org/zap"
"go.uber.org/zap/zapcore"
"golang.org/x/crypto/ssh"
"golang.org/x/crypto/ssh/agent"
"golang.zx2c4.com/wireguard/wgctrl/wgtypes"
"github.com/alvaroaleman/vpnctrl/pkg/ini"
"github.com/alvaroaleman/vpnctrl/types"
)
const listenAddr = 51820
type options struct {
interfaceName string
}
func main() {
logCfg := zap.NewProductionConfig()
logCfg.EncoderConfig.EncodeTime = zapcore.RFC3339TimeEncoder
log, err := logCfg.Build()
if err != nil {
fmt.Printf("failed to construct logger: %v\n", err)
os.Exit(1)
}
defer log.Sync()
hostname, err := os.Hostname()
if err != nil {
log.Fatal("failed to get hostname", zap.Error(err))
}
if uid := os.Geteuid(); uid != 0 {
log.Fatal("Must run as root, but ran with other UID", zap.Int("uid", uid))
}
doToken := os.Getenv("DO_TOKEN")
if doToken == "" {
log.Fatal("DO_TOKEN env var must be set and contain a valid DigitalOcean token")
}
doClient := godo.NewFromToken(doToken)
localCfg, serverPrivKey, err := generateLocalConfig()
if err != nil {
log.Fatal("failed to generate wireguard config", zap.Error(err))
}
serverAddr, err := createServer(context.Background(), log, doClient, serverPrivKey, localCfg.Interface.PrivateKey.PublicKey(), hostname)
if err != nil {
log.Fatal("failed to create server", zap.Error(err))
}
log = log.With(zap.String("server_addr", serverAddr))
log.Info("Created server and got its address")
if err := waitForServer(log, serverAddr); err != nil {
log.Fatal("Failed to wait for server to become reachable", zap.Error(err))
}
localCfg.Peer.Endpoint = serverAddr + ":" + strconv.Itoa(listenAddr)
localCfgSerialized, err := ini.Marshal(localCfg)
if err != nil {
log.Fatal("failed to marshal local wireguard config", zap.Error(err))
}
if err := ioutil.WriteFile("/etc/wireguard/"+hostname+".conf", localCfgSerialized, 0600); err != nil {
log.Fatal("failed to write local wireguard config", zap.Error(err), zap.String("path", "/etc/wireguard/"+hostname+".conf"), zap.String("config", string(localCfgSerialized)))
}
if out, err := exec.Command("wg-quick", "up", hostname).CombinedOutput(); err != nil {
log.Fatal("failed to enable wireguard interface", zap.Error(err), zap.String("output", string(out)))
}
if err := setupRoutes(log, serverAddr); err != nil {
log.Fatal("failed to set up the routes", zap.Error(err))
}
log.Info("Successfully set up everything")
}
func generateLocalConfig() (cfg *types.WireguardConfig, serverPriv *wgtypes.Key, err error) {
serverPrivKey, err := wgtypes.GeneratePrivateKey()
if err != nil {
return nil, nil, fmt.Errorf("failed to generate the private key for the server: %w", err)
}
clientPrivKey, err := wgtypes.GeneratePrivateKey()
if err != nil {
return nil, nil, fmt.Errorf("failed to generate the private key for the client: %w", err)
}
return &types.WireguardConfig{
Interface: types.WireguardInterface{
PrivateKey: clientPrivKey,
Address: "172.18.6.2/24",
Table: "off",
},
Peer: types.WireguardPeer{
PublicKey: serverPrivKey.PublicKey(),
AllowedIPs: "0.0.0.0/0",
PersistentKeepAlive: 15,
},
}, &serverPrivKey, nil
}
func createServer(ctx context.Context,
log *zap.Logger,
client *godo.Client,
privKey *wgtypes.Key,
clientKey wgtypes.Key,
name string,
) (address string, err error) {
wgCfg := types.WireguardConfig{
Interface: types.WireguardInterface{
Address: "172.18.6.1/24",
PrivateKey: *privKey,
ListenPort: listenAddr,
PostUp: "echo 1 > /proc/sys/net/ipv4/ip_forward; iptables -A FORWARD -i wg0 -j ACCEPT; iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE",
PostDown: "iptables -D FORWARD -i wg0 -j ACCEPT; iptables -t nat -D POSTROUTING -o eth0 -j MASQUERADE",
Table: "off",
},
Peer: types.WireguardPeer{
PublicKey: clientKey,
AllowedIPs: "0.0.0.0/0",
},
}
configBytes, err := ini.Marshal(&wgCfg)
if err != nil {
return "", fmt.Errorf("failed to marshal wireguard config: %w", err)
}
configBase64 := base64.StdEncoding.EncodeToString(configBytes)
server, _, err := client.Droplets.Create(ctx, &godo.DropletCreateRequest{
Name: name,
Region: "fra1",
Size: "s-1vcpu-1gb",
Image: godo.DropletCreateImage{Slug: "ubuntu-20-04-x64"},
SSHKeys: []godo.DropletCreateSSHKey{{Fingerprint: "23:2b:a6:6f:06:db:4e:04:fd:41:ca:99:98:f9:41:30"}},
UserData: fmt.Sprintf(`#cloud-config
write_files:
- path: /etc/systemd/system/setup.service
content: |
[Unit]
Description=Setup
After=network-online.target
Requires=network-online.target
[Service]
Type=oneshot
RemainAfterExit=true
ExecStart=/bin/bash -c 'set -euo pipefail; apt update && apt install -y wireguard wireguard-tools && wg-quick up wg0'
[Install]
RequiredBy=multi-user.target
- path: /etc/wireguard/wg0.conf
encoding: b64
content: %s
runcmd:
- systemctl enable --now setup.service
`, configBase64),
})
if err != nil {
return "", fmt.Errorf("failed to create server: %w", err)
}
log.Info("Successfully created server, waiting for IP to be assigned")
timeAfterChan := time.After(30 * time.Second)
id := server.ID
for {
select {
case <-timeAfterChan:
return "", errors.New("timed out waiting for server to be ready")
default:
server, _, err = client.Droplets.Get(ctx, id)
if err != nil {
return "", fmt.Errorf("failed to get droplet: %w", err)
}
if publicAddr := publicAddr(server); publicAddr != "" {
return publicAddr, nil
}
}
}
}
func publicAddr(server *godo.Droplet) string {
for _, network := range server.Networks.V4 {
if network.Type == "public" {
return network.IPAddress
}
}
return ""
}
func waitForServer(log *zap.Logger, addr string) error {
cfg := &ssh.ClientConfig{
User: "root",
Timeout: 10 * time.Second,
HostKeyCallback: ssh.InsecureIgnoreHostKey(),
}
if sshAgent, err := net.Dial("unix", os.Getenv("SSH_AUTH_SOCK")); err == nil {
cfg.Auth = append(cfg.Auth, ssh.PublicKeysCallback(agent.NewClient(sshAgent).Signers))
}
log.Info("Waiting for wireguard server to become reachable")
timeout := time.After(5 * time.Minute)
for {
select {
case <-timeout:
return fmt.Errorf("timeout waiting for %s to become reachable", addr)
default:
connection, err := ssh.Dial("tcp", addr+":22", cfg)
if err != nil {
log.Info("Error establishing ssh connection, retrying...", zap.Error(err))
continue
}
session, err := connection.NewSession()
if err != nil {
return fmt.Errorf("failed to open ssh session: %w", err)
}
if err := session.Run("wg show wg0"); err != nil {
log.Info("Wireguard server not yet up, retrying...")
continue
}
log.Info("Wireguard server became reachable")
return nil
}
}
}
func setupRoutes(log *zap.Logger, ip string) error {
_, endpointNet, err := net.ParseCIDR(ip + "/32")
if err != nil {
return fmt.Errorf("failed to parse %s/32 as ip: %w", ip, err)
}
wgInternalIP := net.IPv4(172, 18, 6, 1)
currentRoutes, err := netlink.RouteList(nil, 4)
if err != nil {
return fmt.Errorf("failed to list routes: %w", err)
}
var hasWGServerRoute bool
var hasDefaultRouteThroughWg bool
var defaultGW net.IP
for _, route := range currentRoutes {
if route.Dst == nil {
if route.Gw.String() == wgInternalIP.String() {
hasDefaultRouteThroughWg = true
} else {
// We assume there is only one default route or two if the WG one was already set up
defaultGW = route.Gw[:]
}
continue
}
if route.Dst.String() == endpointNet.String() {
hasWGServerRoute = true
}
}
if !hasWGServerRoute {
if err := netlink.RouteAdd(&netlink.Route{Dst: endpointNet, Gw: defaultGW}); err != nil {
return fmt.Errorf("failed to add route: %w", err)
}
log.Info("Added route for wireguard endpoint", zap.String("dst", endpointNet.String()), zap.String("gw", defaultGW.String()))
}
if !hasDefaultRouteThroughWg {
if err := netlink.RouteAdd(&netlink.Route{Gw: wgInternalIP}); err != nil {
return fmt.Errorf("failed to add default route through Wireguard: %w", err)
}
log.Info("Added default route through wireguard", zap.String("gw", wgInternalIP.String()))
}
return nil
}