AdGuardHome/internal/home/authratelimiter.go
Eugene Burkov f603c21b55 Pull request: 2826 auth block
Merge in DNS/adguard-home from 2826-auth-block to master

Updates #2826.

Squashed commit of the following:

commit ae87360379270012869ad2bc4e528e07eb9af91e
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Tue Apr 27 15:35:49 2021 +0300

    home: fix mistake

commit dfa2ab05e9a8e70ac1bec36c4eb8ef3b02283b92
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Tue Apr 27 15:31:53 2021 +0300

    home: imp code

commit ff4220d3c3d92ae604e92a0c5c274d9527350d99
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Tue Apr 27 15:14:20 2021 +0300

    home: imp authratelimiter

commit c73a407d8652d64957e35046dbae7168aa45202f
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Tue Apr 27 14:20:17 2021 +0300

    home: fix authratelimiter

commit 724db4380928b055f9995006cf421cbe9c5363e7
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Fri Apr 23 12:15:48 2021 +0300

    home: introduce auth blocker
2021-04-27 18:56:32 +03:00

110 lines
2.6 KiB
Go

package home
import (
"sync"
"time"
)
// failedAuthTTL is the period of time for which the failed attempt will stay in
// cache.
const failedAuthTTL = 1 * time.Minute
// failedAuth is an entry of authRateLimiter's cache.
type failedAuth struct {
until time.Time
num uint
}
// authRateLimiter used to cache failed authentication attempts.
type authRateLimiter struct {
failedAuths map[string]failedAuth
// failedAuthsLock protects failedAuths.
failedAuthsLock sync.Mutex
blockDur time.Duration
maxAttempts uint
}
// newAuthRateLimiter returns properly initialized *authRateLimiter.
func newAuthRateLimiter(blockDur time.Duration, maxAttempts uint) (ab *authRateLimiter) {
return &authRateLimiter{
failedAuths: make(map[string]failedAuth),
blockDur: blockDur,
maxAttempts: maxAttempts,
}
}
// cleanupLocked checks each blocked users removing ones with expired TTL. For
// internal use only.
func (ab *authRateLimiter) cleanupLocked(now time.Time) {
for k, v := range ab.failedAuths {
if now.After(v.until) {
delete(ab.failedAuths, k)
}
}
}
// checkLocked checks the attempter for it's state. For internal use only.
func (ab *authRateLimiter) checkLocked(usrID string, now time.Time) (left time.Duration) {
a, ok := ab.failedAuths[usrID]
if !ok {
return 0
}
if a.num < ab.maxAttempts {
return 0
}
return a.until.Sub(now)
}
// check returns the time left until unblocking. The nonpositive result should
// be interpreted as not blocked attempter.
func (ab *authRateLimiter) check(usrID string) (left time.Duration) {
now := time.Now()
ab.failedAuthsLock.Lock()
defer ab.failedAuthsLock.Unlock()
ab.cleanupLocked(now)
return ab.checkLocked(usrID, now)
}
// incLocked increments the number of unsuccessful attempts for attempter with
// ip and updates it's blocking moment if needed. For internal use only.
func (ab *authRateLimiter) incLocked(usrID string, now time.Time) {
var until time.Time = now.Add(failedAuthTTL)
var attNum uint = 1
a, ok := ab.failedAuths[usrID]
if ok {
until = a.until
attNum = a.num + 1
}
if attNum >= ab.maxAttempts {
until = now.Add(ab.blockDur)
}
ab.failedAuths[usrID] = failedAuth{
num: attNum,
until: until,
}
}
// inc updates the failed attempt in cache.
func (ab *authRateLimiter) inc(usrID string) {
now := time.Now()
ab.failedAuthsLock.Lock()
defer ab.failedAuthsLock.Unlock()
ab.incLocked(usrID, now)
}
// remove stops any tracking and any blocking of the user.
func (ab *authRateLimiter) remove(usrID string) {
ab.failedAuthsLock.Lock()
defer ab.failedAuthsLock.Unlock()
delete(ab.failedAuths, usrID)
}