mirror of
https://github.com/ergochat/ergo.git
synced 2024-11-29 23:49:25 +01:00
125 lines
3.3 KiB
Go
125 lines
3.3 KiB
Go
// Copyright (c) 2016-2017 Daniel Oaks <daniel@danieloaks.net>
|
|
// released under the MIT license
|
|
|
|
package connection_limits
|
|
|
|
import (
|
|
"errors"
|
|
"fmt"
|
|
"net"
|
|
"sync"
|
|
|
|
"github.com/oragono/oragono/irc/utils"
|
|
)
|
|
|
|
// LimiterConfig controls the automated connection limits.
|
|
type LimiterConfig struct {
|
|
Enabled bool
|
|
CidrLenIPv4 int `yaml:"cidr-len-ipv4"`
|
|
CidrLenIPv6 int `yaml:"cidr-len-ipv6"`
|
|
ConnsPerSubnet int `yaml:"connections-per-subnet"`
|
|
IPsPerSubnet int `yaml:"ips-per-subnet"` // legacy name for ConnsPerSubnet
|
|
Exempted []string
|
|
}
|
|
|
|
var (
|
|
errTooManyClients = errors.New("Too many clients in subnet")
|
|
)
|
|
|
|
// Limiter manages the automated client connection limits.
|
|
type Limiter struct {
|
|
sync.Mutex
|
|
|
|
enabled bool
|
|
ipv4Mask net.IPMask
|
|
ipv6Mask net.IPMask
|
|
// subnetLimit is the maximum number of clients per subnet
|
|
subnetLimit int
|
|
// population holds IP -> count of clients connected from there
|
|
population map[string]int
|
|
|
|
// exemptedNets holds networks that are exempt from limits
|
|
exemptedNets []net.IPNet
|
|
}
|
|
|
|
// addrToKey canonicalizes `addr` to a string key.
|
|
func addrToKey(addr net.IP, v4Mask net.IPMask, v6Mask net.IPMask) string {
|
|
if addr.To4() != nil {
|
|
addr = addr.Mask(v4Mask) // IP.Mask() handles the 4-in-6 mapping for us
|
|
} else {
|
|
addr = addr.Mask(v6Mask)
|
|
}
|
|
return addr.String()
|
|
}
|
|
|
|
// AddClient adds a client to our population if possible. If we can't, throws an error instead.
|
|
// 'force' is used to add already-existing clients (i.e. ones that are already on the network).
|
|
func (cl *Limiter) AddClient(addr net.IP, force bool) error {
|
|
cl.Lock()
|
|
defer cl.Unlock()
|
|
|
|
// we don't track populations for exempted addresses or nets - this is by design
|
|
if !cl.enabled || utils.IPInNets(addr, cl.exemptedNets) {
|
|
return nil
|
|
}
|
|
|
|
// check population
|
|
addrString := addrToKey(addr, cl.ipv4Mask, cl.ipv6Mask)
|
|
|
|
if cl.population[addrString]+1 > cl.subnetLimit && !force {
|
|
return errTooManyClients
|
|
}
|
|
|
|
cl.population[addrString] = cl.population[addrString] + 1
|
|
|
|
return nil
|
|
}
|
|
|
|
// RemoveClient removes the given address from our population
|
|
func (cl *Limiter) RemoveClient(addr net.IP) {
|
|
cl.Lock()
|
|
defer cl.Unlock()
|
|
|
|
if !cl.enabled || utils.IPInNets(addr, cl.exemptedNets) {
|
|
return
|
|
}
|
|
|
|
addrString := addrToKey(addr, cl.ipv4Mask, cl.ipv6Mask)
|
|
cl.population[addrString] = cl.population[addrString] - 1
|
|
|
|
// safety limiter
|
|
if cl.population[addrString] < 0 {
|
|
cl.population[addrString] = 0
|
|
}
|
|
}
|
|
|
|
// ApplyConfig atomically applies a config update to a connection limit handler
|
|
func (cl *Limiter) ApplyConfig(config LimiterConfig) error {
|
|
// assemble exempted nets
|
|
exemptedNets, err := utils.ParseNetList(config.Exempted)
|
|
if err != nil {
|
|
return fmt.Errorf("Could not parse limiter exemption list: %v", err.Error())
|
|
}
|
|
|
|
cl.Lock()
|
|
defer cl.Unlock()
|
|
|
|
if cl.population == nil {
|
|
cl.population = make(map[string]int)
|
|
}
|
|
|
|
cl.enabled = config.Enabled
|
|
cl.ipv4Mask = net.CIDRMask(config.CidrLenIPv4, 32)
|
|
cl.ipv6Mask = net.CIDRMask(config.CidrLenIPv6, 128)
|
|
// subnetLimit is explicitly NOT capped at a minimum of one.
|
|
// this is so that CL config can be used to allow ONLY clients from exempted IPs/nets
|
|
cl.subnetLimit = config.ConnsPerSubnet
|
|
// but: check if the current key was left unset, but the legacy was set:
|
|
if cl.subnetLimit == 0 && config.IPsPerSubnet != 0 {
|
|
cl.subnetLimit = config.IPsPerSubnet
|
|
}
|
|
cl.exemptedNets = exemptedNets
|
|
|
|
return nil
|
|
}
|