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|
package portallocator
import (
"errors"
"fmt"
"net"
"sync"
)
type portMap struct {
p map[int]struct{}
last int
}
type (
protocolMap map[string]*portMap
ipMapping map[string]protocolMap
)
const (
BeginPortRange = 49153
EndPortRange = 65535
)
var (
ErrAllPortsAllocated = errors.New("all ports are allocated")
ErrUnknownProtocol = errors.New("unknown protocol")
)
var (
mutex sync.Mutex
defaultIP = net.ParseIP("0.0.0.0")
globalMap = ipMapping{}
)
type ErrPortAlreadyAllocated struct {
ip string
port int
}
func NewErrPortAlreadyAllocated(ip string, port int) ErrPortAlreadyAllocated {
return ErrPortAlreadyAllocated{
ip: ip,
port: port,
}
}
func (e ErrPortAlreadyAllocated) IP() string {
return e.ip
}
func (e ErrPortAlreadyAllocated) Port() int {
return e.port
}
func (e ErrPortAlreadyAllocated) IPPort() string {
return fmt.Sprintf("%s:%d", e.ip, e.port)
}
func (e ErrPortAlreadyAllocated) Error() string {
return fmt.Sprintf("Bind for %s:%d failed: port is already allocated", e.ip, e.port)
}
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 _, ok := mapping[proto].p[port]; !ok {
mapping[proto].p[port] = struct{}{}
return port, nil
} else {
return 0, NewErrPortAlreadyAllocated(ip.String(), port)
}
} 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)[proto]
delete(mapping.p, 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{p: map[int]struct{}{}, last: 0},
"udp": &portMap{p: map[int]struct{}{}, last: 0},
}
}
return globalMap[ipstr]
}
func findPort(ip net.IP, proto string) (int, error) {
mapping := getOrCreate(ip)[proto]
if mapping.last == 0 {
mapping.p[BeginPortRange] = struct{}{}
mapping.last = BeginPortRange
return BeginPortRange, nil
}
for port := mapping.last + 1; port != mapping.last; port++ {
if port > EndPortRange {
port = BeginPortRange
}
if _, ok := mapping.p[port]; !ok {
mapping.p[port] = struct{}{}
mapping.last = port
return port, nil
}
}
return 0, ErrAllPortsAllocated
}
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
}
|
