390 lines
9.7 KiB
Go
390 lines
9.7 KiB
Go
package headscale
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import (
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"bytes"
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"context"
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"crypto/rand"
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"encoding/hex"
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"errors"
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"fmt"
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"html/template"
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"net/http"
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"regexp"
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"strings"
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"time"
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"github.com/coreos/go-oidc/v3/oidc"
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"github.com/gin-gonic/gin"
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"github.com/patrickmn/go-cache"
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"github.com/rs/zerolog/log"
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"golang.org/x/oauth2"
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"gorm.io/gorm"
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"tailscale.com/types/key"
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)
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const (
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oidcStateCacheExpiration = time.Minute * 5
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oidcStateCacheCleanupInterval = time.Minute * 10
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randomByteSize = 16
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)
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type IDTokenClaims struct {
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Name string `json:"name,omitempty"`
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Groups []string `json:"groups,omitempty"`
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Email string `json:"email"`
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Username string `json:"preferred_username,omitempty"`
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}
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func (h *Headscale) initOIDC() error {
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var err error
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// grab oidc config if it hasn't been already
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if h.oauth2Config == nil {
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h.oidcProvider, err = oidc.NewProvider(context.Background(), h.cfg.OIDC.Issuer)
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if err != nil {
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log.Error().
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Err(err).
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Caller().
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Msgf("Could not retrieve OIDC Config: %s", err.Error())
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return err
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}
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h.oauth2Config = &oauth2.Config{
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ClientID: h.cfg.OIDC.ClientID,
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ClientSecret: h.cfg.OIDC.ClientSecret,
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Endpoint: h.oidcProvider.Endpoint(),
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RedirectURL: fmt.Sprintf(
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"%s/oidc/callback",
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strings.TrimSuffix(h.cfg.ServerURL, "/"),
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),
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Scopes: []string{oidc.ScopeOpenID, "profile", "email"},
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}
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}
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// init the state cache if it hasn't been already
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if h.oidcStateCache == nil {
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h.oidcStateCache = cache.New(
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oidcStateCacheExpiration,
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oidcStateCacheCleanupInterval,
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)
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}
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return nil
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}
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// RegisterOIDC redirects to the OIDC provider for authentication
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// Puts machine key in cache so the callback can retrieve it using the oidc state param
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// Listens in /oidc/register/:mKey.
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func (h *Headscale) RegisterOIDC(ctx *gin.Context) {
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machineKeyStr := ctx.Param("mkey")
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if machineKeyStr == "" {
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ctx.String(http.StatusBadRequest, "Wrong params")
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return
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}
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log.Trace().
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Caller().
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Str("machine_key", machineKeyStr).
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Msg("Received oidc register call")
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randomBlob := make([]byte, randomByteSize)
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if _, err := rand.Read(randomBlob); err != nil {
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log.Error().
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Caller().
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Msg("could not read 16 bytes from rand")
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ctx.String(http.StatusInternalServerError, "could not read 16 bytes from rand")
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return
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}
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stateStr := hex.EncodeToString(randomBlob)[:32]
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// place the machine key into the state cache, so it can be retrieved later
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h.oidcStateCache.Set(stateStr, machineKeyStr, oidcStateCacheExpiration)
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authURL := h.oauth2Config.AuthCodeURL(stateStr)
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log.Debug().Msgf("Redirecting to %s for authentication", authURL)
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ctx.Redirect(http.StatusFound, authURL)
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}
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type oidcCallbackTemplateConfig struct {
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User string
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Verb string
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}
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var oidcCallbackTemplate = template.Must(
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template.New("oidccallback").Parse(`<html>
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<body>
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<h1>headscale</h1>
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<p>
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{{.Verb}} as {{.User}}, you can now close this window.
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</p>
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</body>
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</html>`),
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)
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// OIDCCallback handles the callback from the OIDC endpoint
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// Retrieves the mkey from the state cache and adds the machine to the users email namespace
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// TODO: A confirmation page for new machines should be added to avoid phishing vulnerabilities
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// TODO: Add groups information from OIDC tokens into machine HostInfo
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// Listens in /oidc/callback.
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func (h *Headscale) OIDCCallback(ctx *gin.Context) {
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code := ctx.Query("code")
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state := ctx.Query("state")
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if code == "" || state == "" {
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ctx.String(http.StatusBadRequest, "Wrong params")
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return
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}
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oauth2Token, err := h.oauth2Config.Exchange(context.Background(), code)
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if err != nil {
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ctx.String(http.StatusBadRequest, "Could not exchange code for token")
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return
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}
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log.Trace().
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Caller().
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Str("code", code).
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Str("state", state).
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Msg("Got oidc callback")
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rawIDToken, rawIDTokenOK := oauth2Token.Extra("id_token").(string)
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if !rawIDTokenOK {
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ctx.String(http.StatusBadRequest, "Could not extract ID Token")
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return
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}
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verifier := h.oidcProvider.Verifier(&oidc.Config{ClientID: h.cfg.OIDC.ClientID})
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idToken, err := verifier.Verify(context.Background(), rawIDToken)
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if err != nil {
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log.Error().
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Err(err).
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Caller().
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Msg("failed to verify id token")
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ctx.String(http.StatusBadRequest, "Failed to verify id token")
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return
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}
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// TODO: we can use userinfo at some point to grab additional information about the user (groups membership, etc)
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// userInfo, err := oidcProvider.UserInfo(context.Background(), oauth2.StaticTokenSource(oauth2Token))
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// if err != nil {
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// c.String(http.StatusBadRequest, fmt.Sprintf("Failed to retrieve userinfo"))
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// return
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// }
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// Extract custom claims
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var claims IDTokenClaims
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if err = idToken.Claims(&claims); err != nil {
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log.Error().
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Err(err).
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Caller().
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Msg("Failed to decode id token claims")
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ctx.String(
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http.StatusBadRequest,
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"Failed to decode id token claims",
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)
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return
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}
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// retrieve machinekey from state cache
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machineKeyIf, machineKeyFound := h.oidcStateCache.Get(state)
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if !machineKeyFound {
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log.Error().
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Msg("requested machine state key expired before authorisation completed")
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ctx.String(http.StatusBadRequest, "state has expired")
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return
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}
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machineKeyStr, machineKeyOK := machineKeyIf.(string)
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var machineKey key.MachinePublic
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err = machineKey.UnmarshalText([]byte(MachinePublicKeyEnsurePrefix(machineKeyStr)))
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if err != nil {
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log.Error().
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Msg("could not parse machine public key")
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ctx.String(http.StatusBadRequest, "could not parse public key")
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return
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}
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if !machineKeyOK {
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log.Error().Msg("could not get machine key from cache")
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ctx.String(
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http.StatusInternalServerError,
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"could not get machine key from cache",
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)
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return
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}
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// TODO(kradalby): Currently, if it fails to find a requested expiry, non will be set
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requestedTime := time.Time{}
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if requestedTimeIf, found := h.requestedExpiryCache.Get(machineKey.String()); found {
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if reqTime, ok := requestedTimeIf.(time.Time); ok {
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requestedTime = reqTime
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}
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}
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// retrieve machine information
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machine, err := h.GetMachineByMachineKey(machineKey)
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if err != nil {
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log.Error().Msg("machine key not found in database")
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ctx.String(
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http.StatusInternalServerError,
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"could not get machine info from database",
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)
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return
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}
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if machine.isRegistered() {
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log.Trace().
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Caller().
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Str("machine", machine.Name).
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Msg("machine already registered, reauthenticating")
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h.RefreshMachine(machine, requestedTime)
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var content bytes.Buffer
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if err := oidcCallbackTemplate.Execute(&content, oidcCallbackTemplateConfig{
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User: claims.Email,
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Verb: "Reauthenticated",
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}); err != nil {
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log.Error().
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Str("func", "OIDCCallback").
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Str("type", "reauthenticate").
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Err(err).
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Msg("Could not render OIDC callback template")
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ctx.Data(
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http.StatusInternalServerError,
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"text/html; charset=utf-8",
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[]byte("Could not render OIDC callback template"),
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)
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}
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ctx.Data(http.StatusOK, "text/html; charset=utf-8", content.Bytes())
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return
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}
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now := time.Now().UTC()
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if namespaceName, ok := h.getNamespaceFromEmail(claims.Email); ok {
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// register the machine if it's new
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if !machine.Registered {
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log.Debug().Msg("Registering new machine after successful callback")
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namespace, err := h.GetNamespace(namespaceName)
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if errors.Is(err, gorm.ErrRecordNotFound) {
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namespace, err = h.CreateNamespace(namespaceName)
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if err != nil {
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log.Error().
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Err(err).
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Caller().
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Msgf("could not create new namespace '%s'", namespaceName)
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ctx.String(
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http.StatusInternalServerError,
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"could not create new namespace",
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)
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return
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}
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} else if err != nil {
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log.Error().
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Caller().
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Err(err).
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Str("namespace", namespaceName).
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Msg("could not find or create namespace")
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ctx.String(
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http.StatusInternalServerError,
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"could not find or create namespace",
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)
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return
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}
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ip, err := h.getAvailableIP()
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if err != nil {
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log.Error().
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Caller().
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Err(err).
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Msg("could not get an IP from the pool")
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ctx.String(
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http.StatusInternalServerError,
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"could not get an IP from the pool",
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)
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return
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}
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machine.IPAddress = ip.String()
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machine.NamespaceID = namespace.ID
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machine.Registered = true
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machine.RegisterMethod = RegisterMethodOIDC
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machine.LastSuccessfulUpdate = &now
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machine.Expiry = &requestedTime
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h.db.Save(&machine)
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}
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var content bytes.Buffer
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if err := oidcCallbackTemplate.Execute(&content, oidcCallbackTemplateConfig{
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User: claims.Email,
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Verb: "Authenticated",
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}); err != nil {
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log.Error().
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Str("func", "OIDCCallback").
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Str("type", "authenticate").
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Err(err).
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Msg("Could not render OIDC callback template")
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ctx.Data(
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http.StatusInternalServerError,
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"text/html; charset=utf-8",
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[]byte("Could not render OIDC callback template"),
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)
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}
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ctx.Data(http.StatusOK, "text/html; charset=utf-8", content.Bytes())
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return
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}
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log.Error().
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Caller().
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Str("email", claims.Email).
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Str("username", claims.Username).
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Str("machine", machine.Name).
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Msg("Email could not be mapped to a namespace")
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ctx.String(
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http.StatusBadRequest,
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"email from claim could not be mapped to a namespace",
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)
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}
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// getNamespaceFromEmail passes the users email through a list of "matchers"
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// and iterates through them until it matches and returns a namespace.
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// If no match is found, an empty string will be returned.
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// TODO(kradalby): golang Maps key order is not stable, so this list is _not_ deterministic. Find a way to make the list of keys stable, preferably in the order presented in a users configuration.
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func (h *Headscale) getNamespaceFromEmail(email string) (string, bool) {
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for match, namespace := range h.cfg.OIDC.MatchMap {
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regex := regexp.MustCompile(match)
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if regex.MatchString(email) {
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return namespace, true
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}
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}
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return "", false
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}
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