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|
package portallocator
import (
"errors"
"net"
"sync"
)
type (
portMap map[int]bool
protocolMap map[string]portMap
ipMapping map[string]protocolMap
)
const (
BeginPortRange = 49153
EndPortRange = 65535
)
var (
ErrAllPortsAllocated = errors.New("all ports are allocated")
ErrPortAlreadyAllocated = errors.New("port has already been allocated")
ErrUnknownProtocol = errors.New("unknown protocol")
)
var (
mutex sync.Mutex
defaultIP = net.ParseIP("0.0.0.0")
globalMap = ipMapping{}
)
func RequestPort(ip net.IP, proto string, port int) (int, error) {
mutex.Lock()
defer mutex.Unlock()
if err := validateProto(proto); err != nil {
return 0, err
}
ip = getDefault(ip)
mapping := getOrCreate(ip)
if port > 0 {
if !mapping[proto][port] {
mapping[proto][port] = true
return port, nil
} else {
return 0, ErrPortAlreadyAllocated
}
} else {
port, err := findPort(ip, proto)
if err != nil {
return 0, err
}
return port, nil
}
}
func ReleasePort(ip net.IP, proto string, port int) error {
mutex.Lock()
defer mutex.Unlock()
ip = getDefault(ip)
mapping := getOrCreate(ip)
delete(mapping[proto], port)
return nil
}
func ReleaseAll() error {
mutex.Lock()
defer mutex.Unlock()
globalMap = ipMapping{}
return nil
}
func getOrCreate(ip net.IP) protocolMap {
ipstr := ip.String()
if _, ok := globalMap[ipstr]; !ok {
globalMap[ipstr] = protocolMap{
"tcp": portMap{},
"udp": portMap{},
}
}
return globalMap[ipstr]
}
func findPort(ip net.IP, proto string) (int, error) {
port := BeginPortRange
mapping := getOrCreate(ip)
for mapping[proto][port] {
port++
if port > EndPortRange {
return 0, ErrAllPortsAllocated
}
}
mapping[proto][port] = true
return port, nil
}
func getDefault(ip net.IP) net.IP {
if ip == nil {
return defaultIP
}
return ip
}
func validateProto(proto string) error {
if proto != "tcp" && proto != "udp" {
return ErrUnknownProtocol
}
return nil
}
|
