mediocre-go-lib/cmd/totp-proxy/main.go

111 lines
3.4 KiB
Go

package main
/*
totp-proxy is a reverse proxy which implements basic time-based one-time
password (totp) authentication for any website.
It takes in a JSON object which maps usernames to totp secrets (generated at
a site like https://freeotp.github.io/qrcode.html), as well as a url to
proxy requests to. Users are prompted with a basic-auth prompt, and if they
succeed their totp challenge a cookie is set and requests are proxied to the
destination.
*/
import (
"net/http"
"net/url"
"time"
"github.com/mediocregopher/mediocre-go-lib/m"
"github.com/mediocregopher/mediocre-go-lib/mcfg"
"github.com/mediocregopher/mediocre-go-lib/mcrypto"
"github.com/mediocregopher/mediocre-go-lib/mctx"
"github.com/mediocregopher/mediocre-go-lib/mhttp"
"github.com/mediocregopher/mediocre-go-lib/mlog"
"github.com/mediocregopher/mediocre-go-lib/mrand"
"github.com/mediocregopher/mediocre-go-lib/mrun"
"github.com/mediocregopher/mediocre-go-lib/mtime"
"github.com/pquerna/otp/totp"
)
func main() {
ctx := mctx.New()
logger := mlog.From(ctx)
cookieName := mcfg.String(ctx, "cookie-name", "_totp_proxy", "String to use as the name for cookies")
cookieTimeout := mcfg.Duration(ctx, "cookie-timeout", mtime.Duration{1 * time.Hour}, "Timeout for cookies")
var userSecrets map[string]string
mcfg.RequiredJSON(ctx, "users", &userSecrets, "JSON object which maps usernames to their TOTP secret strings")
var secret mcrypto.Secret
secretStr := mcfg.String(ctx, "secret", "", "String used to sign authentication tokens. If one isn't given a new one will be generated on each startup, invalidating all previous tokens.")
mrun.OnStart(ctx, func(mctx.Context) error {
if *secretStr == "" {
*secretStr = mrand.Hex(32)
}
logger.Info("generating secret")
secret = mcrypto.NewSecret([]byte(*secretStr))
return nil
})
proxyHandler := new(struct{ http.Handler })
proxyURL := mcfg.RequiredString(ctx, "dst-url", "URL to proxy requests to. Only the scheme and host should be set.")
mrun.OnStart(ctx, func(mctx.Context) error {
u, err := url.Parse(*proxyURL)
if err != nil {
return err
}
proxyHandler.Handler = mhttp.ReverseProxy(u)
return nil
})
authHandler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
authLogger := logger.WithKV(mlog.CtxKV(r.Context()))
unauthorized := func() {
w.Header().Add("WWW-Authenticate", "Basic")
w.WriteHeader(http.StatusUnauthorized)
}
authorized := func() {
sig := mcrypto.SignString(secret, "")
http.SetCookie(w, &http.Cookie{
Name: *cookieName,
Value: sig.String(),
MaxAge: int((*cookieTimeout).Seconds()),
})
proxyHandler.ServeHTTP(w, r)
}
if cookie, _ := r.Cookie(*cookieName); cookie != nil {
authLogger.Debug("authenticating with cookie", mlog.KV{"cookie": cookie.String()})
var sig mcrypto.Signature
if err := sig.UnmarshalText([]byte(cookie.Value)); err == nil {
err := mcrypto.VerifyString(secret, sig, "")
if err == nil && time.Since(sig.Time()) < (*cookieTimeout).Duration {
authorized()
return
}
}
}
if user, pass, ok := r.BasicAuth(); ok && pass != "" {
logger.Debug("authenticating with user/pass", mlog.KV{
"user": user,
"pass": pass,
})
if userSecret, ok := userSecrets[user]; ok {
if totp.Validate(pass, userSecret) {
authorized()
return
}
}
}
unauthorized()
})
mhttp.MListenAndServe(ctx, authHandler)
m.Run(ctx)
}