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// Copyright 2020 The Prometheus Authors
// This code is partly borrowed from Caddy:
// Copyright 2015 Matthew Holt and The Caddy Authors
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package web
import (
"encoding/hex"
"net/http"
"sync"
"github.com/go-kit/kit/log"
"golang.org/x/crypto/bcrypt"
)
func validateUsers(configPath string) error {
c, err := getConfig(configPath)
if err != nil {
return err
}
for _, p := range c.Users {
_, err = bcrypt.Cost([]byte(p))
if err != nil {
return err
}
}
return nil
}
type userAuthRoundtrip struct {
tlsConfigPath string
handler http.Handler
logger log.Logger
cache *cache
// bcryptMtx is there to ensure that bcrypt.CompareHashAndPassword is run
// only once in parallel as this is CPU intensive.
bcryptMtx sync.Mutex
}
func (u *userAuthRoundtrip) ServeHTTP(w http.ResponseWriter, r *http.Request) {
c, err := getConfig(u.tlsConfigPath)
if err != nil {
u.logger.Log("msg", "Unable to parse configuration", "err", err)
http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
return
}
if len(c.Users) == 0 {
u.handler.ServeHTTP(w, r)
return
}
user, pass, auth := r.BasicAuth()
if auth {
hashedPassword, validUser := c.Users[user]
if !validUser {
// The user is not found. Use a fixed password hash to
// prevent user enumeration by timing requests.
// This is a bcrypt-hashed version of "fakepassword".
hashedPassword = "$2y$10$QOauhQNbBCuQDKes6eFzPeMqBSjb7Mr5DUmpZ/VcEd00UAV/LDeSi"
}
cacheKey := hex.EncodeToString(append(append([]byte(user), []byte(hashedPassword)...), []byte(pass)...))
authOk, ok := u.cache.get(cacheKey)
if !ok {
// This user, hashedPassword, password is not cached.
u.bcryptMtx.Lock()
err := bcrypt.CompareHashAndPassword([]byte(hashedPassword), []byte(pass))
u.bcryptMtx.Unlock()
authOk = err == nil
u.cache.set(cacheKey, authOk)
}
if authOk && validUser {
u.handler.ServeHTTP(w, r)
return
}
}
w.Header().Set("WWW-Authenticate", "Basic")
http.Error(w, http.StatusText(http.StatusUnauthorized), http.StatusUnauthorized)
}
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