create separate irc/connection_limiting package

irc/connection_throttling.go

@@ -1,167 +0,0 @@
-// Copyright (c) 2016-2017 Daniel Oaks <daniel@danieloaks.net>
-// released under the MIT license
-
-package irc
-
-import (
-	"fmt"
-	"net"
-	"sync"
-	"time"
-)
-
-// ThrottleDetails holds the connection-throttling details for a subnet/IP.
-type ThrottleDetails struct {
-	Start       time.Time
-	ClientCount int
-}
-
-// ConnectionThrottle manages automated client connection throttling.
-type ConnectionThrottle struct {
-	sync.RWMutex
-
-	enabled     bool
-	ipv4Mask    net.IPMask
-	ipv6Mask    net.IPMask
-	subnetLimit int
-	duration    time.Duration
-	population  map[string]ThrottleDetails
-
-	// used by the server to ban clients that go over this limit
-	banDuration time.Duration
-	banMessage  string
-
-	// exemptedIPs holds IPs that are exempt from limits
-	exemptedIPs map[string]bool
-	// exemptedNets holds networks that are exempt from limits
-	exemptedNets []net.IPNet
-}
-
-// maskAddr masks the given IPv4/6 address with our cidr limit masks.
-func (ct *ConnectionThrottle) maskAddr(addr net.IP) net.IP {
-	if addr.To4() == nil {
-		// IPv6 addr
-		addr = addr.Mask(ct.ipv6Mask)
-	} else {
-		// IPv4 addr
-		addr = addr.Mask(ct.ipv4Mask)
-	}
-
-	return addr
-}
-
-// ResetFor removes any existing count for the given address.
-func (ct *ConnectionThrottle) ResetFor(addr net.IP) {
-	ct.Lock()
-	defer ct.Unlock()
-
-	if !ct.enabled {
-		return
-	}
-
-	// remove
-	ct.maskAddr(addr)
-	addrString := addr.String()
-	delete(ct.population, addrString)
-}
-
-// AddClient introduces a new client connection if possible. If we can't, throws an error instead.
-func (ct *ConnectionThrottle) AddClient(addr net.IP) error {
-	ct.Lock()
-	defer ct.Unlock()
-
-	if !ct.enabled {
-		return nil
-	}
-
-	// check exempted lists
-	if ct.exemptedIPs[addr.String()] {
-		return nil
-	}
-	for _, ex := range ct.exemptedNets {
-		if ex.Contains(addr) {
-			return nil
-		}
-	}
-
-	// check throttle
-	ct.maskAddr(addr)
-	addrString := addr.String()
-
-	details, exists := ct.population[addrString]
-	if !exists || details.Start.Add(ct.duration).Before(time.Now()) {
-		details = ThrottleDetails{
-			Start: time.Now(),
-		}
-	}
-
-	if details.ClientCount+1 > ct.subnetLimit {
-		return errTooManyClients
-	}
-
-	details.ClientCount++
-	ct.population[addrString] = details
-
-	return nil
-}
-
-func (ct *ConnectionThrottle) BanDuration() time.Duration {
-	ct.RLock()
-	defer ct.RUnlock()
-
-	return ct.banDuration
-}
-
-func (ct *ConnectionThrottle) BanMessage() string {
-	ct.RLock()
-	defer ct.RUnlock()
-
-	return ct.banMessage
-}
-
-// NewConnectionThrottle returns a new client connection throttler.
-// The throttler is functional, but disabled; it can be enabled via `ApplyConfig`.
-func NewConnectionThrottle() *ConnectionThrottle {
-	var ct ConnectionThrottle
-
-	// initialize empty population; all other state is configurable
-	ct.population = make(map[string]ThrottleDetails)
-
-	return &ct
-}
-
-// ApplyConfig atomically applies a config update to a throttler
-func (ct *ConnectionThrottle) ApplyConfig(config ConnectionThrottleConfig) error {
-	// assemble exempted nets
-	exemptedIPs := make(map[string]bool)
-	var exemptedNets []net.IPNet
-	for _, cidr := range config.Exempted {
-		ipaddr := net.ParseIP(cidr)
-		_, netaddr, err := net.ParseCIDR(cidr)
-
-		if ipaddr == nil && err != nil {
-			return fmt.Errorf("Could not parse exempted IP/network [%s]", cidr)
-		}
-
-		if ipaddr != nil {
-			exemptedIPs[ipaddr.String()] = true
-		} else {
-			exemptedNets = append(exemptedNets, *netaddr)
-		}
-	}
-
-	ct.Lock()
-	defer ct.Unlock()
-
-	ct.enabled = config.Enabled
-	ct.ipv4Mask = net.CIDRMask(config.CidrLenIPv4, 32)
-	ct.ipv6Mask = net.CIDRMask(config.CidrLenIPv6, 128)
-	ct.subnetLimit = config.ConnectionsPerCidr
-	ct.duration = config.Duration
-	ct.banDuration = config.BanDuration
-	ct.banMessage = config.BanMessage
-	ct.exemptedIPs = exemptedIPs
-	ct.exemptedNets = exemptedNets
-
-	return nil
-}