Smack Jingle java.net.BindException: Cannot assign requested address: Cannot bind

运行Smack Jingle demo时(http://fisheye.igniterealtime.org/browse/~raw,r=11613/smack/trunk/jingle/extension/source/org/jivesoftware/smackx/jingle/mediaimpl/demo/Demo.java)总会遇到下面的异常:

Java代码

1. java.net.BindException:Cannotassignrequestedaddress:Cannotbind
2. atjava.net.PlainDatagramSocketImpl.bind0(NativeMethod)
3. atjava.net.PlainDatagramSocketImpl.bind(UnknownSource)
4. atjava.net.DatagramSocket.bind(UnknownSource)
5. atjava.net.DatagramSocket.<init>(UnknownSource)
6. atjava.net.DatagramSocket.<init>(UnknownSource)
7. atde.javawi.jstun.test.demo.ice.Candidate.<init>(Candidate.java:44)
8. atde.javawi.jstun.test.demo.ice.ICENegociator.gatherCandidateAddresses(ICENegociator.java:87)
9. atorg.jivesoftware.smackx.jingle.nat.ICEResolver.initialize(ICEResolver.java:81)
10. atorg.jivesoftware.smackx.jingle.nat.TransportResolver.initializeAndWait(TransportResolver.java:387)
11. atorg.jivesoftware.smackx.jingle.nat.ICETransportManager.<init>(ICETransportManager.java:36)
12. atcom.haojie.smack.demo.Demo.initialize(Demo.java:84)
13. atcom.haojie.smack.demo.Demo.<init>(Demo.java:76)
14. atcom.haojie.smack.demo.Demo.main(Demo.java:170)

可以发现是所使用的JSTUN库出了问题. JSTUN位于http://jstun.javawi.de/. 于是下载了jstun-0.7.3.src.tar.gz, 运行其中的de.javawi.jstun.test.demo.ice.ICENegociator, 还是有同样的问题:

Java代码

1. java.net.BindException:Cannotassignrequestedaddress:Cannotbind
2. atjava.net.PlainDatagramSocketImpl.bind0(NativeMethod)
3. atjava.net.PlainDatagramSocketImpl.bind(UnknownSource)
4. atjava.net.DatagramSocket.bind(UnknownSource)
5. atjava.net.DatagramSocket.<init>(UnknownSource)
6. atjava.net.DatagramSocket.<init>(UnknownSource)
7. atde.javawi.jstun.test.demo.ice.Candidate.<init>(Candidate.java:44)
8. atde.javawi.jstun.test.demo.ice.ICENegociator.gatherCandidateAddresses(ICENegociator.java:89)
9. atde.javawi.jstun.test.demo.ice.ICENegociator.main(ICENegociator.java:176)

经过调试,发现了原因.
ICENegociator类的gatherCandidateAddresses()方法是用来收集candidates地址的, 它首先获取local地址,作为host candidate,然后从这个地址向指定的STUN服务器发送STUN请求,获取server reflexive candidate address. 对于这些地址都会创建一个Candidate对象. 在Candidate类的构造函数里问题出现了, 先看Candidate构造函数:

Java代码

1. publicCandidate(Addressaddress,shortcomponentId)throwsSocketException,UnknownHostException,UtilityException{
2. this.socket=newDatagramSocket(0,address.getInetAddress());
3. this.type=CandidateType.Local;
4. this.componentId=componentId;
5. this.priority=0;
6. this.base=this;
7. this.isInUse=false;
8. }
10. publicCandidate(Addressaddress,CandidateTypetype,shortcomponentId,Candidatebase)throwsSocketException,UnknownHostException,UtilityException{
11. this.socket=newDatagramSocket(0,address.getInetAddress());
12. this.type=type;
13. setComponentId(componentId);
14. this.priority=0;
15. this.base=base;
16. this.isInUse=false;
17. }

在Candidate类的构造函数里,会创建一个DatagramSocket, DatagramSocket构造函数的第二参数是socket要绑定的local address. 对于host candidate, DatagramSocket的创建没有问题,因为host candidate就是local address; 但对于server reflexive candidate address, 问题出现了, 因为这个地址是NAT转换后的地址, socket无法绑定上去的.

所以改动如下, 判断CandidateType, 如果是ServerReflexive, 则不创建socket.主要的代码为:

Java代码

1. publicclassDiscoveryInfo{
2. .......
3. privateintpublicPort;//用于保存NAT转换后的端口
4. publicintgetPublicPort(){
5. returnpublicPort;
6. }
7. publicvoidsetPublicPort(intpublicPort){
8. this.publicPort=publicPort;
9. }
10. ......
11. }
13. publicclassICENegociator{
14. .......
15. publicvoidgatherCandidateAddresses(){
16. ......
17. DiscoveryTesttest=newDiscoveryTest(iaddress,stunServer,stunPort);
18. DiscoveryInfodi=test.test();
19. if(di.getPublicIP()!=null){
20. Candidatecand=newCandidate(newAddress(di.getPublicIP().getAddress()),CandidateType.ServerReflexive,componentId,local);
21. cand.setPort(di.getPublicPort());
22. ......
23. }
24. }
25. ......
26. }
28. publicclassDiscoveryTest{
29. privatebooleantest1()throwsUtilityException,SocketException,UnknownHostException,IOException,MessageAttributeParsingException,MessageHeaderParsingException{
30. ......
31. di.setPublicIP(ma.getAddress().getInetAddress());
32. di.setPublicPort(ma.getPort());
33. ......
34. }
35. }
37. publicclassCandidateimplementsComparable{
38. ......
39. privateintport;
41. publicCandidate(Addressaddress,CandidateTypetype,shortcomponentId,Candidatebase)throwsSocketException,UnknownHostException,UtilityException{
42. if(type==CandidateType.Local){
43. this.socket=newDatagramSocket(0,address.getInetAddress());
44. this.address=null;
45. }else{
46. this.address=address;
47. this.socket=null;
48. }
50. this.type=type;
51. setComponentId(componentId);
52. this.priority=0;
53. this.base=base;
54. this.isInUse=false;
55. }
57. publicAddressgetAddress()throwsUtilityException{
58. if(type==CandidateType.Local){
59. returnnewAddress(socket.getLocalAddress().getAddress());
60. }else{
61. returnthis.address;
62. }
63. }
65. publicintgetPort(){
66. if(type==CandidateType.Local){
67. returnsocket.getLocalPort();
68. }else{
69. returnthis.port;
70. }
71. }
73. publicvoidsetPort(intport){
74. this.port=port;
75. }
76. }

转自：http://mysuperbaby.iteye.com/blog/901370