A fast and simple blog backend.
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mediocre-blog/src/http/auth.go

94 lines
2.0 KiB

package http
import (
"context"
"net/http"
"time"
"github.com/mediocregopher/blog.mediocregopher.com/srv/http/apiutil"
"golang.org/x/crypto/bcrypt"
)
// NewPasswordHash returns the hash of the given plaintext password, for use
// with Auther.
func NewPasswordHash(plaintext string) string {
hashedPassword, err := bcrypt.GenerateFromPassword([]byte(plaintext), 13)
if err != nil {
panic(err)
}
return string(hashedPassword)
}
// Auther determines who can do what.
type Auther interface {
Allowed(ctx context.Context, username, password string) bool
Close() error
}
type auther struct {
users map[string]string
ticker *time.Ticker
}
// NewAuther initializes and returns an Auther will which allow the given
// username and password hash combinations. Password hashes must have been
// created using NewPasswordHash.
func NewAuther(users map[string]string, ratelimit time.Duration) Auther {
return &auther{
users: users,
ticker: time.NewTicker(ratelimit),
}
}
func (a *auther) Close() error {
a.ticker.Stop()
return nil
}
func (a *auther) Allowed(ctx context.Context, username, password string) bool {
select {
case <-ctx.Done():
return false
case <-a.ticker.C:
}
hashedPassword, ok := a.users[username]
if !ok {
return false
}
err := bcrypt.CompareHashAndPassword(
[]byte(hashedPassword), []byte(password),
)
return err == nil
}
func authMiddleware(auther Auther) middleware {
respondUnauthorized := func(rw http.ResponseWriter, r *http.Request) {
rw.Header().Set("WWW-Authenticate", `Basic realm="NOPE"`)
rw.WriteHeader(http.StatusUnauthorized)
apiutil.GetRequestLogger(r).WarnString(r.Context(), "unauthorized")
}
return func(h http.Handler) http.Handler {
return http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
username, password, ok := r.BasicAuth()
if !ok {
respondUnauthorized(rw, r)
return
}
if !auther.Allowed(r.Context(), username, password) {
respondUnauthorized(rw, r)
return
}
h.ServeHTTP(rw, r)
})
}
}