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