Perm structs and config

internal/perm/perm.go

@@ -0,0 +1,90 @@
+package perm
+
+import (
+	"net"
+	"strconv"
+	"sync"
+)
+
+// Perm matches address:port strings to Actions
+// loaded from a Config.
+//
+// It's thread safe.
+type Perm struct {
+	lock sync.RWMutex
+
+	perm map[string]Action
+	def  Action
+}
+
+// New creates a new Perm struct from a Config.
+//
+// You can also &perm.Perm{} and then call Load on it.
+func New(c *Config) (p *Perm) {
+	p = &Perm{}
+	p.Load(c)
+	return
+}
+
+// Load loads/reloads the Perm struct.
+func (p *Perm) Load(c *Config) {
+	p.lock.Lock()
+	defer p.lock.Unlock()
+
+	if p.perm == nil {
+		p.perm = make(map[string]Action)
+	} else {
+		clear(p.perm)
+	}
+
+	p.def = c.DefaultAction
+
+	// insert helper to use the most severe action existing
+	insert := func(addrport string, action Action) {
+		existing_action, ok := p.perm[addrport]
+		if ok {
+			p.perm[addrport] = MostSevere(existing_action, action)
+		} else {
+			p.perm[addrport] = action
+		}
+	}
+
+	// loop around the Match map
+	for addrport, act := range c.Match {
+		addr, port := splitHostPort(addrport)
+		if port != "" {
+			insert(net.JoinHostPort(addr, port), act)
+		} else {
+			// so this is why def_port shouldn't be that big
+			// TODO change this to sth faster
+			for def_port := range c.DefaultPort {
+				insert(net.JoinHostPort(addr, strconv.Itoa(def_port)), act)
+			}
+		}
+	}
+
+	return
+}
+
+// Match matches an address to an action.
+// addr must be in net.JoinHostPort format.
+func (p *Perm) Match(addr string) Action {
+	// sanity check
+	if p == nil {
+		return ActionDeny
+	}
+
+	p.lock.RLock()
+	defer p.lock.RUnlock()
+
+	// sanity check no.2
+	if p.perm == nil {
+		return p.def
+	}
+
+	action, ok := p.perm[addr]
+	if !ok {
+		return p.def
+	}
+	return action
+}