/
main.go
318 lines (277 loc) · 8.17 KB
/
main.go
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package main
import (
"bytes"
"encoding/json"
"fmt"
"io"
"log"
"net/http"
"net/url"
"os"
"regexp"
"strings"
"sync"
"golang.org/x/net/context"
"golang.org/x/oauth2/google"
)
// ref: https://accounts.google.com/.well-known/openid-configuration
const (
oauthURL = "https://accounts.google.com/o/oauth2/auth?redirect_uri=%s&response_type=code&client_id=%s&scope=openid+email+profile&approval_prompt=force&access_type=offline"
tokenURL = "https://oauth2.googleapis.com/token"
userInfoURL = "https://www.googleapis.com/oauth2/v3/userinfo"
adminUserURL = "https://www.googleapis.com/admin/directory/v1/users"
sshKeyPostBody = `{"customSchemas":{"keys":{"ssh":"%s"}}}`
form = `<!DOCTYPE html>
<html>
<body>
<form action="/submit">
*public* ed25519 ssh key (500 chars or less)<br>
<input type="text" name="key"><br>
<input type="hidden" name="token" value="%s">
<input type="submit" value="Submit">
</form>
</body>
</html>
`
// http://emailregex.com/
emailRegexStr = "^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\\.[a-zA-Z0-9-.]+$"
)
var (
googleClientID = os.Getenv("SKM_CLIENT_ID")
googleClientSecret = os.Getenv("SKM_CLIENT_SECRET")
googleCallbackURL = os.Getenv("SKM_CALLBACK_URL")
googleAdminEmail = os.Getenv("SKM_ADMIN_EMAIL")
awsBucket = os.Getenv("SKM_AWS_BUCKET")
saKeyLoc = os.Getenv("SKM_SA_KEY_LOC")
groups = os.Getenv("SKM_GROUPS")
scopes = []string{"https://www.googleapis.com/auth/admin.directory.user", "https://www.googleapis.com/auth/admin.directory.group.member.readonly"}
syncMutex = &sync.RWMutex{}
emailRegex = regexp.MustCompile(emailRegexStr)
)
type userInfo struct {
Email string `json:"email"`
}
type tokenResponse struct {
AccessToken string `json:"access_token"`
RefreshToken string `json:"refresh_token"`
IDToken string `json:"id_token"`
}
// Validate arguments
func validate() {
var err error
// Client ID
clientIDRegex := regexp.MustCompile("^.*apps\\.googleusercontent\\.com$")
if !clientIDRegex.MatchString(googleClientID) {
log.Fatalln(googleClientID + " is not a valid client ID")
}
// Client secret
if googleClientSecret == "" {
log.Fatalln("client secret must not be empty")
}
// Callback URL
u, err := url.ParseRequestURI(googleCallbackURL)
if err != nil || (u.Host == "" || u.Scheme == "") {
log.Fatalln(googleCallbackURL + " is not a valid URI")
}
// Admin email string
if len(googleAdminEmail) > 254 || !emailRegex.MatchString(googleAdminEmail) {
log.Fatalln(googleAdminEmail + " is not a valid email address")
}
// AWS S3 bucket
if awsBucket == "" {
log.Fatalln("SKM_AWS_BUCKET must not be empty")
}
// SA key location
_, err = os.Stat(saKeyLoc)
if os.IsNotExist(err) {
log.Fatalln(saKeyLoc + " does not exist")
} else if err != nil {
log.Fatalln("can't stat " + saKeyLoc)
}
}
func fmtGroups() []string {
groups := strings.Split(groups, " ")
if len(groups) == 0 {
log.Fatalln("SKM_GROUPS can't be empty")
}
for i, _ := range groups {
groups[i] = strings.TrimSpace(groups[i])
if !emailRegex.MatchString(groups[i]) {
log.Fatalf("Group is not a valid email: group=%s\n", groups[i])
}
}
return groups
}
// Get the id_token and refresh_token from google
func getTokens(clientID, clientSecret, code string) (*tokenResponse, error) {
val := url.Values{}
val.Add("grant_type", "authorization_code")
val.Add("redirect_uri", googleCallbackURL)
val.Add("client_id", clientID)
val.Add("client_secret", clientSecret)
val.Add("code", code)
resp, err := http.PostForm(tokenURL, val)
if err != nil {
return nil, err
}
defer func() {
io.Copy(io.Discard, resp.Body)
resp.Body.Close()
}()
if resp.StatusCode != 200 {
return nil, fmt.Errorf("google - unexpected response: %d calling %s", resp.StatusCode, tokenURL)
}
if err != nil {
return nil, err
}
tr := &tokenResponse{}
err = json.NewDecoder(resp.Body).Decode(tr)
if err != nil {
return nil, err
}
return tr, nil
}
func getUserEmail(accessToken string) (string, error) {
uri, _ := url.Parse(userInfoURL)
q := uri.Query()
q.Set("alt", "json")
q.Set("access_token", accessToken)
uri.RawQuery = q.Encode()
resp, err := http.Get(uri.String())
if err != nil {
return "", err
}
defer func() {
io.Copy(io.Discard, resp.Body)
resp.Body.Close()
}()
if resp.StatusCode != 200 {
return "", fmt.Errorf("google - unexpected response: %d calling %s", resp.StatusCode, uri.String())
}
ui := &userInfo{}
err = json.NewDecoder(resp.Body).Decode(ui)
if err != nil {
return "", err
}
return ui.Email, nil
}
func authenticatedClient() (client *http.Client) {
data, err := os.ReadFile(saKeyLoc)
if err != nil {
log.Fatal(err)
}
conf, err := google.JWTConfigFromJSON(data, scopes...)
conf.Subject = googleAdminEmail
if err != nil {
log.Fatal(err)
}
return conf.Client(context.TODO())
}
func googleRedirect() http.Handler {
redirectURL := fmt.Sprintf(oauthURL, googleCallbackURL, googleClientID)
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
http.Redirect(w, r, redirectURL, http.StatusFound)
})
}
func googleCallback() http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
code := r.URL.Query().Get("code")
tokResponse, err := getTokens(googleClientID, googleClientSecret, code)
if err != nil {
log.Printf("Error getting tokens: %s", err)
w.WriteHeader(http.StatusInternalServerError)
return
}
_, err = fmt.Fprintf(w, form, tokResponse.AccessToken)
if err != nil {
log.Println("failed to write about response")
w.WriteHeader(http.StatusInternalServerError)
return
}
})
}
func validateKey(key string) error {
if !strings.HasPrefix(key, "ssh-ed25519") {
return fmt.Errorf("The key must be of type ssh-ed25519")
}
if len(key) > 500 {
return fmt.Errorf("The key string must be less then 500 chars")
}
return nil
}
func submit(adminClient *http.Client) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
key := r.FormValue("key")
err := validateKey(key)
if err != nil {
w.WriteHeader(http.StatusBadRequest)
fmt.Fprintf(w, err.Error())
return
}
token := r.FormValue("token")
email, err := getUserEmail(token)
if err != nil {
log.Printf("Error getting user email: %s", err)
w.WriteHeader(http.StatusInternalServerError)
return
}
// strip the comment and replace with email
keyParts := strings.Split(key, " ")
key = keyParts[0] + " " + keyParts[1] + " " + email
userKeysURI := fmt.Sprintf("%s/%s", adminUserURL, email)
req, _ := http.NewRequest(http.MethodPut, userKeysURI, strings.NewReader(fmt.Sprintf(sshKeyPostBody, key)))
req.Header.Set("content-type", "application/json")
resp, err := adminClient.Do(req)
if err != nil {
log.Printf("Failed to make a PUT request to update user: %s", err)
w.WriteHeader(http.StatusInternalServerError)
return
}
defer func() {
io.Copy(io.Discard, resp.Body)
resp.Body.Close()
}()
buf := new(bytes.Buffer)
buf.ReadFrom(resp.Body)
body := buf.Bytes()
if resp.StatusCode != 200 {
log.Printf("Got: %d calling: %s body: %s", resp.StatusCode, userKeysURI, body)
w.WriteHeader(http.StatusInternalServerError)
return
}
if !bytes.Contains(body, []byte(key)) {
log.Printf("PUT happened, but didn't return the new value for the ssh key: %s body: %s", key, body)
w.WriteHeader(http.StatusInternalServerError)
return
}
_, err = fmt.Fprintf(w, "Successfully set ssh public key: %s", key)
if err != nil {
log.Println("failed to write sucessful user key update response")
w.WriteHeader(http.StatusInternalServerError)
return
}
})
}
func authMapPage(am *authMap) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
syncMutex.RLock()
defer syncMutex.RUnlock()
enc := json.NewEncoder(w)
enc.Encode(am)
})
}
func main() {
validate()
groups := fmtGroups()
adminClient := authenticatedClient()
am := &authMap{client: adminClient, inputGroups: groups}
go am.sync()
m := http.NewServeMux()
m.Handle("/", googleRedirect())
m.Handle("/callback", googleCallback())
m.Handle("/submit", submit(adminClient))
m.Handle("/authmap", authMapPage(am))
http.Handle("/", m)
log.Println("Listening on :8080")
http.ListenAndServe(":8080", nil)
}