package headscale
import (
"encoding/binary"
"encoding/json"
"errors"
"fmt"
"io"
"log"
"net/http"
"time"
"github.com/gin-gonic/gin"
"github.com/klauspost/compress/zstd"
"gorm.io/datatypes"
"gorm.io/gorm"
"inet.af/netaddr"
"tailscale.com/tailcfg"
"tailscale.com/types/wgkey"
)
// KeyHandler provides the Headscale pub key
// Listens in /key
func (h *Headscale) KeyHandler(c *gin.Context) {
c.Data(200, "text/plain; charset=utf-8", []byte(h.publicKey.HexString()))
}
// RegisterWebAPI shows a simple message in the browser to point to the CLI
// Listens in /register
func (h *Headscale) RegisterWebAPI(c *gin.Context) {
mKeyStr := c.Query("key")
if mKeyStr == "" {
c.String(http.StatusBadRequest, "Wrong params")
return
}
// spew.Dump(c.Params)
c.Data(http.StatusOK, "text/html; charset=utf-8", []byte(fmt.Sprintf(`
headscale
Run the command below in the headscale server to add this machine to your network:
headscale -n NAMESPACE node register %s
`, mKeyStr)))
}
// RegistrationHandler handles the actual registration process of a machine
// Endpoint /machine/:id
func (h *Headscale) RegistrationHandler(c *gin.Context) {
body, _ := io.ReadAll(c.Request.Body)
mKeyStr := c.Param("id")
mKey, err := wgkey.ParseHex(mKeyStr)
if err != nil {
log.Printf("Cannot parse machine key: %s", err)
c.String(http.StatusInternalServerError, "Sad!")
return
}
req := tailcfg.RegisterRequest{}
err = decode(body, &req, &mKey, h.privateKey)
if err != nil {
log.Printf("Cannot decode message: %s", err)
c.String(http.StatusInternalServerError, "Very sad!")
return
}
db, err := h.db()
if err != nil {
log.Printf("Cannot open DB: %s", err)
c.String(http.StatusInternalServerError, ":(")
return
}
var m Machine
if result := db.First(&m, "machine_key = ?", mKey.HexString()); errors.Is(result.Error, gorm.ErrRecordNotFound) {
log.Println("New Machine!")
m = Machine{
Expiry: &req.Expiry,
MachineKey: mKey.HexString(),
Name: req.Hostinfo.Hostname,
NodeKey: wgkey.Key(req.NodeKey).HexString(),
}
if err := db.Create(&m).Error; err != nil {
log.Printf("Could not create row: %s", err)
return
}
}
if !m.Registered && req.Auth.AuthKey != "" {
h.handleAuthKey(c, db, mKey, req, m)
return
}
resp := tailcfg.RegisterResponse{}
// We have the updated key!
if m.NodeKey == wgkey.Key(req.NodeKey).HexString() {
if m.Registered {
log.Printf("[%s] Client is registered and we have the current NodeKey. All clear to /map", m.Name)
resp.AuthURL = ""
resp.MachineAuthorized = true
resp.User = *m.Namespace.toUser()
respBody, err := encode(resp, &mKey, h.privateKey)
if err != nil {
log.Printf("Cannot encode message: %s", err)
c.String(http.StatusInternalServerError, "")
return
}
c.Data(200, "application/json; charset=utf-8", respBody)
return
}
log.Printf("[%s] Not registered and not NodeKey rotation. Sending a authurl to register", m.Name)
resp.AuthURL = fmt.Sprintf("%s/register?key=%s",
h.cfg.ServerURL, mKey.HexString())
respBody, err := encode(resp, &mKey, h.privateKey)
if err != nil {
log.Printf("Cannot encode message: %s", err)
c.String(http.StatusInternalServerError, "")
return
}
c.Data(200, "application/json; charset=utf-8", respBody)
return
}
// The NodeKey we have matches OldNodeKey, which means this is a refresh after an key expiration
if m.NodeKey == wgkey.Key(req.OldNodeKey).HexString() {
log.Printf("[%s] We have the OldNodeKey in the database. This is a key refresh", m.Name)
m.NodeKey = wgkey.Key(req.NodeKey).HexString()
db.Save(&m)
resp.AuthURL = ""
resp.User = *m.Namespace.toUser()
respBody, err := encode(resp, &mKey, h.privateKey)
if err != nil {
log.Printf("Cannot encode message: %s", err)
c.String(http.StatusInternalServerError, "Extremely sad!")
return
}
c.Data(200, "application/json; charset=utf-8", respBody)
return
}
// We arrive here after a client is restarted without finalizing the authentication flow or
// when headscale is stopped in the middle of the auth process.
if m.Registered {
log.Printf("[%s] The node is sending us a new NodeKey, but machine is registered. All clear for /map", m.Name)
resp.AuthURL = ""
resp.MachineAuthorized = true
resp.User = *m.Namespace.toUser()
respBody, err := encode(resp, &mKey, h.privateKey)
if err != nil {
log.Printf("Cannot encode message: %s", err)
c.String(http.StatusInternalServerError, "")
return
}
c.Data(200, "application/json; charset=utf-8", respBody)
return
}
log.Printf("[%s] The node is sending us a new NodeKey, sending auth url", m.Name)
resp.AuthURL = fmt.Sprintf("%s/register?key=%s",
h.cfg.ServerURL, mKey.HexString())
respBody, err := encode(resp, &mKey, h.privateKey)
if err != nil {
log.Printf("Cannot encode message: %s", err)
c.String(http.StatusInternalServerError, "")
return
}
c.Data(200, "application/json; charset=utf-8", respBody)
}
// PollNetMapHandler takes care of /machine/:id/map
//
// This is the busiest endpoint, as it keeps the HTTP long poll that updates
// the clients when something in the network changes.
//
// The clients POST stuff like HostInfo and their Endpoints here, but
// only after their first request (marked with the ReadOnly field).
//
// At this moment the updates are sent in a quite horrendous way, but they kinda work.
func (h *Headscale) PollNetMapHandler(c *gin.Context) {
body, _ := io.ReadAll(c.Request.Body)
mKeyStr := c.Param("id")
mKey, err := wgkey.ParseHex(mKeyStr)
if err != nil {
log.Printf("Cannot parse client key: %s", err)
return
}
req := tailcfg.MapRequest{}
err = decode(body, &req, &mKey, h.privateKey)
if err != nil {
log.Printf("Cannot decode message: %s", err)
return
}
db, err := h.db()
if err != nil {
log.Printf("Cannot open DB: %s", err)
return
}
var m Machine
if result := db.First(&m, "machine_key = ?", mKey.HexString()); errors.Is(result.Error, gorm.ErrRecordNotFound) {
log.Printf("Ignoring request, cannot find machine with key %s", mKey.HexString())
return
}
hostinfo, _ := json.Marshal(req.Hostinfo)
m.Name = req.Hostinfo.Hostname
m.HostInfo = datatypes.JSON(hostinfo)
m.DiscoKey = wgkey.Key(req.DiscoKey).HexString()
now := time.Now().UTC()
// From Tailscale client:
//
// ReadOnly is whether the client just wants to fetch the MapResponse,
// without updating their Endpoints. The Endpoints field will be ignored and
// LastSeen will not be updated and peers will not be notified of changes.
//
// The intended use is for clients to discover the DERP map at start-up
// before their first real endpoint update.
if !req.ReadOnly {
endpoints, _ := json.Marshal(req.Endpoints)
m.Endpoints = datatypes.JSON(endpoints)
m.LastSeen = &now
}
db.Save(&m)
pollData := make(chan []byte, 1)
update := make(chan []byte, 1)
cancelKeepAlive := make(chan []byte, 1)
defer close(pollData)
defer close(cancelKeepAlive)
h.pollMu.Lock()
h.clientsPolling[m.ID] = update
h.pollMu.Unlock()
data, err := h.getMapResponse(mKey, req, m)
if err != nil {
c.String(http.StatusInternalServerError, ":(")
return
}
// We update our peers if the client is not sending ReadOnly in the MapRequest
// so we don't distribute its initial request (it comes with
// empty endpoints to peers)
// Details on the protocol can be found in https://github.com/tailscale/tailscale/blob/main/tailcfg/tailcfg.go#L696
log.Printf("[%s] ReadOnly=%t OmitPeers=%t Stream=%t", m.Name, req.ReadOnly, req.OmitPeers, req.Stream)
if req.ReadOnly {
log.Printf("[%s] Client is starting up. Asking for DERP map", m.Name)
c.Data(200, "application/json; charset=utf-8", *data)
return
}
if req.OmitPeers && !req.Stream {
log.Printf("[%s] Client sent endpoint update and is ok with a response without peer list", m.Name)
c.Data(200, "application/json; charset=utf-8", *data)
return
} else if req.OmitPeers && req.Stream {
log.Printf("[%s] Warning, ignoring request, don't know how to handle it", m.Name)
c.String(http.StatusBadRequest, "")
return
}
log.Printf("[%s] Client is ready to access the tailnet", m.Name)
log.Printf("[%s] Sending initial map", m.Name)
pollData <- *data
log.Printf("[%s] Notifying peers", m.Name)
peers, _ := h.getPeers(m)
h.pollMu.Lock()
for _, p := range *peers {
pUp, ok := h.clientsPolling[uint64(p.ID)]
if ok {
log.Printf("[%s] Notifying peer %s (%s)", m.Name, p.Name, p.Addresses[0])
pUp <- []byte{}
} else {
log.Printf("[%s] Peer %s does not appear to be polling", m.Name, p.Name)
}
}
h.pollMu.Unlock()
go h.keepAlive(cancelKeepAlive, pollData, mKey, req, m)
c.Stream(func(w io.Writer) bool {
select {
case data := <-pollData:
log.Printf("[%s] Sending data (%d bytes)", m.Name, len(data))
_, err := w.Write(data)
if err != nil {
log.Printf("[%s] 🤮 Cannot write data: %s", m.Name, err)
}
now := time.Now().UTC()
m.LastSeen = &now
db.Save(&m)
return true
case <-update:
log.Printf("[%s] Received a request for update", m.Name)
data, err := h.getMapResponse(mKey, req, m)
if err != nil {
log.Printf("[%s] Could not get the map update: %s", m.Name, err)
}
_, err = w.Write(*data)
if err != nil {
log.Printf("[%s] Could not write the map response: %s", m.Name, err)
}
return true
case <-c.Request.Context().Done():
log.Printf("[%s] The client has closed the connection", m.Name)
now := time.Now().UTC()
m.LastSeen = &now
db.Save(&m)
h.pollMu.Lock()
cancelKeepAlive <- []byte{}
delete(h.clientsPolling, m.ID)
close(update)
h.pollMu.Unlock()
return false
}
})
}
func (h *Headscale) keepAlive(cancel chan []byte, pollData chan []byte, mKey wgkey.Key, req tailcfg.MapRequest, m Machine) {
for {
select {
case <-cancel:
return
default:
h.pollMu.Lock()
data, err := h.getMapKeepAliveResponse(mKey, req, m)
if err != nil {
log.Printf("Error generating the keep alive msg: %s", err)
return
}
log.Printf("[%s] Sending keepalive", m.Name)
pollData <- *data
h.pollMu.Unlock()
time.Sleep(60 * time.Second)
}
}
}
func (h *Headscale) getMapResponse(mKey wgkey.Key, req tailcfg.MapRequest, m Machine) (*[]byte, error) {
node, err := m.toNode()
if err != nil {
log.Printf("Cannot convert to node: %s", err)
return nil, err
}
peers, err := h.getPeers(m)
if err != nil {
log.Printf("Cannot fetch peers: %s", err)
return nil, err
}
resp := tailcfg.MapResponse{
KeepAlive: false,
Node: node,
Peers: *peers,
DNS: []netaddr.IP{},
SearchPaths: []string{},
Domain: "foobar@example.com",
PacketFilter: *h.aclRules,
DERPMap: h.cfg.DerpMap,
UserProfiles: []tailcfg.UserProfile{},
}
var respBody []byte
if req.Compress == "zstd" {
src, _ := json.Marshal(resp)
encoder, _ := zstd.NewWriter(nil)
srcCompressed := encoder.EncodeAll(src, nil)
respBody, err = encodeMsg(srcCompressed, &mKey, h.privateKey)
if err != nil {
return nil, err
}
} else {
respBody, err = encode(resp, &mKey, h.privateKey)
if err != nil {
return nil, err
}
}
// spew.Dump(resp)
// declare the incoming size on the first 4 bytes
data := make([]byte, 4)
binary.LittleEndian.PutUint32(data, uint32(len(respBody)))
data = append(data, respBody...)
return &data, nil
}
func (h *Headscale) getMapKeepAliveResponse(mKey wgkey.Key, req tailcfg.MapRequest, m Machine) (*[]byte, error) {
resp := tailcfg.MapResponse{
KeepAlive: true,
}
var respBody []byte
var err error
if req.Compress == "zstd" {
src, _ := json.Marshal(resp)
encoder, _ := zstd.NewWriter(nil)
srcCompressed := encoder.EncodeAll(src, nil)
respBody, err = encodeMsg(srcCompressed, &mKey, h.privateKey)
if err != nil {
return nil, err
}
} else {
respBody, err = encode(resp, &mKey, h.privateKey)
if err != nil {
return nil, err
}
}
data := make([]byte, 4)
binary.LittleEndian.PutUint32(data, uint32(len(respBody)))
data = append(data, respBody...)
return &data, nil
}
func (h *Headscale) handleAuthKey(c *gin.Context, db *gorm.DB, idKey wgkey.Key, req tailcfg.RegisterRequest, m Machine) {
resp := tailcfg.RegisterResponse{}
pak, err := h.checkKeyValidity(req.Auth.AuthKey)
if err != nil {
resp.MachineAuthorized = false
respBody, err := encode(resp, &idKey, h.privateKey)
if err != nil {
log.Printf("Cannot encode message: %s", err)
c.String(http.StatusInternalServerError, "")
return
}
c.Data(200, "application/json; charset=utf-8", respBody)
log.Printf("[%s] Failed authentication via AuthKey", m.Name)
return
}
ip, err := h.getAvailableIP()
if err != nil {
log.Println(err)
return
}
m.AuthKeyID = uint(pak.ID)
m.IPAddress = ip.String()
m.NamespaceID = pak.NamespaceID
m.NodeKey = wgkey.Key(req.NodeKey).HexString() // we update it just in case
m.Registered = true
m.RegisterMethod = "authKey"
db.Save(&m)
resp.MachineAuthorized = true
resp.User = *pak.Namespace.toUser()
respBody, err := encode(resp, &idKey, h.privateKey)
if err != nil {
log.Printf("Cannot encode message: %s", err)
c.String(http.StatusInternalServerError, "Extremely sad!")
return
}
c.Data(200, "application/json; charset=utf-8", respBody)
log.Printf("[%s] Successfully authenticated via AuthKey", m.Name)
}