1 files changed, 103 insertions, 0 deletions
diff --git a/ntcp/map.go b/ntcp/map.go
new file mode 100644
index 0000000..6127149
--- /dev/null
+++ b/ntcp/map.go
@@ -0,0 +1,103 @@
+// Copyright 2021 SNIX LLC sina@snix.ir
+//
+// This program is free software; you can redistribute it and/or
+// modify it under the terms of the GNU General Public License
+// version 2 as published by the Free Software Foundation.
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+package ntcp
+
+import (
+	"errors"
+	"goshkan/opts"
+	"goshkan/rgxp"
+	"regexp"
+	"sync"
+	"time"
+)
+
+type memoryTTL struct {
+	ticker *time.Ticker // age-out trigger
+	stopfc func() error // delete by user trigger
+}
+
+var inMemMap sync.Map // safe map
+var cleanint time.Duration
+
+func setupCache() {
+	switch opts.Settings.Clearc {
+	case 0: // zero map ttl, disable map cache
+		opts.SYSLOG(disabledMAP)
+		allowedOrNot = func(domain string) bool { return rgxp.RegexpCompiled().MatchString(domain) }
+		storeToMap = func(domain string) {}
+		RemoveFromMap = func(ptrn *string) error { return nil }
+
+		return
+	}
+
+	cleanint = time.Duration(opts.Settings.Clearc) * time.Second
+}
+
+var storeToMap = func(domain string) {
+	if ttl, ok := inMemMap.Load(domain); ok {
+		ttl.(memoryTTL).ticker.Reset(cleanint) // renew domain age.
+		return
+	}
+
+	tk := time.NewTicker(cleanint) // new ticker
+	ch := make(chan struct{})
+	fn := func() error {
+		var err error
+		select {
+		case ch <- struct{}{}:
+			return err
+		default:
+			return errors.New(errorChanNk)
+		}
+	}
+
+	inMemMap.Store(domain, memoryTTL{ticker: tk, stopfc: fn}) // add data to map
+	go cleanerMap(tk, domain, ch)                             // run cleaner
+}
+
+func cleanerMap(tk *time.Ticker, dm string, chtr <-chan struct{}) {
+	select {
+	case <-tk.C: // age out, remove form map
+	case <-chtr: // signal by user, remove from map
+	}
+	tk.Stop() // release ticker, its time to die.
+	inMemMap.Delete(dm)
+
+}
+
+var RemoveFromMap = func(ptrn *string) error {
+	re, err := regexp.Compile(*ptrn)
+	if err != nil {
+		return err // somthing is wrong!
+	}
+
+	rgtask := func(key interface{}, value interface{}) bool {
+		if re.MatchString(key.(string)) {
+			if err := value.(memoryTTL).stopfc(); err != nil {
+				opts.SYSLOG(err)
+			} // remove domain from map
+		}
+		return true
+	}
+
+	inMemMap.Range(rgtask)
+	return err
+}
+
+var allowedOrNot = func(domain string) bool {
+	// check memory cache first -> O(1)
+	if _, ok := inMemMap.Load(domain); ok {
+		return ok
+	}
+
+	// this take time, but we can do nothing about it :/
+	return rgxp.RegexpCompiled().MatchString(domain)
+}