github.com/fcwu/docker@v1.4.2-0.20150115145920-2a69ca89f0df/daemon/networkdriver/portallocator/portallocator.go (about)

     1  package portallocator
     2  
     3  import (
     4  	"errors"
     5  	"fmt"
     6  	"net"
     7  	"sync"
     8  )
     9  
    10  type portMap struct {
    11  	p    map[int]struct{}
    12  	last int
    13  }
    14  
    15  func newPortMap() *portMap {
    16  	return &portMap{
    17  		p:    map[int]struct{}{},
    18  		last: EndPortRange,
    19  	}
    20  }
    21  
    22  type protoMap map[string]*portMap
    23  
    24  func newProtoMap() protoMap {
    25  	return protoMap{
    26  		"tcp": newPortMap(),
    27  		"udp": newPortMap(),
    28  	}
    29  }
    30  
    31  type ipMapping map[string]protoMap
    32  
    33  const (
    34  	BeginPortRange = 49153
    35  	EndPortRange   = 65535
    36  )
    37  
    38  var (
    39  	ErrAllPortsAllocated = errors.New("all ports are allocated")
    40  	ErrUnknownProtocol   = errors.New("unknown protocol")
    41  )
    42  
    43  var (
    44  	mutex sync.Mutex
    45  
    46  	defaultIP = net.ParseIP("0.0.0.0")
    47  	globalMap = ipMapping{}
    48  )
    49  
    50  type ErrPortAlreadyAllocated struct {
    51  	ip   string
    52  	port int
    53  }
    54  
    55  func NewErrPortAlreadyAllocated(ip string, port int) ErrPortAlreadyAllocated {
    56  	return ErrPortAlreadyAllocated{
    57  		ip:   ip,
    58  		port: port,
    59  	}
    60  }
    61  
    62  func (e ErrPortAlreadyAllocated) IP() string {
    63  	return e.ip
    64  }
    65  
    66  func (e ErrPortAlreadyAllocated) Port() int {
    67  	return e.port
    68  }
    69  
    70  func (e ErrPortAlreadyAllocated) IPPort() string {
    71  	return fmt.Sprintf("%s:%d", e.ip, e.port)
    72  }
    73  
    74  func (e ErrPortAlreadyAllocated) Error() string {
    75  	return fmt.Sprintf("Bind for %s:%d failed: port is already allocated", e.ip, e.port)
    76  }
    77  
    78  // RequestPort requests new port from global ports pool for specified ip and proto.
    79  // If port is 0 it returns first free port. Otherwise it cheks port availability
    80  // in pool and return that port or error if port is already busy.
    81  func RequestPort(ip net.IP, proto string, port int) (int, error) {
    82  	mutex.Lock()
    83  	defer mutex.Unlock()
    84  
    85  	if proto != "tcp" && proto != "udp" {
    86  		return 0, ErrUnknownProtocol
    87  	}
    88  
    89  	if ip == nil {
    90  		ip = defaultIP
    91  	}
    92  	ipstr := ip.String()
    93  	protomap, ok := globalMap[ipstr]
    94  	if !ok {
    95  		protomap = newProtoMap()
    96  		globalMap[ipstr] = protomap
    97  	}
    98  	mapping := protomap[proto]
    99  	if port > 0 {
   100  		if _, ok := mapping.p[port]; !ok {
   101  			mapping.p[port] = struct{}{}
   102  			return port, nil
   103  		}
   104  		return 0, NewErrPortAlreadyAllocated(ipstr, port)
   105  	}
   106  
   107  	port, err := mapping.findPort()
   108  	if err != nil {
   109  		return 0, err
   110  	}
   111  	return port, nil
   112  }
   113  
   114  // ReleasePort releases port from global ports pool for specified ip and proto.
   115  func ReleasePort(ip net.IP, proto string, port int) error {
   116  	mutex.Lock()
   117  	defer mutex.Unlock()
   118  
   119  	if ip == nil {
   120  		ip = defaultIP
   121  	}
   122  	protomap, ok := globalMap[ip.String()]
   123  	if !ok {
   124  		return nil
   125  	}
   126  	delete(protomap[proto].p, port)
   127  	return nil
   128  }
   129  
   130  // ReleaseAll releases all ports for all ips.
   131  func ReleaseAll() error {
   132  	mutex.Lock()
   133  	globalMap = ipMapping{}
   134  	mutex.Unlock()
   135  	return nil
   136  }
   137  
   138  func (pm *portMap) findPort() (int, error) {
   139  	port := pm.last
   140  	for i := 0; i <= EndPortRange-BeginPortRange; i++ {
   141  		port++
   142  		if port > EndPortRange {
   143  			port = BeginPortRange
   144  		}
   145  
   146  		if _, ok := pm.p[port]; !ok {
   147  			pm.p[port] = struct{}{}
   148  			pm.last = port
   149  			return port, nil
   150  		}
   151  	}
   152  	return 0, ErrAllPortsAllocated
   153  }