无法从java连接到仅IPv6主机

Question

我有一些仅限IPv6的主机.我可以通过curl成功执行curl请求

$ curl -I my.ip.v6.only.host
HTTP/1.1 200 OK

但是当我试图从java获取它时我有一个错误:

HttpGet httpget = new HttpGet("http://my.ip.v6.only.host");
CloseableHttpResponse response = httpclient.execute(httpget);    

堆栈跟踪:

INFO: I/O exception (java.net.NoRouteToHostException) caught when processing request to {}->http://my.ip.v6.only.host: No route to host
Mar 17, 2015 7:42:23 PM org.apache.http.impl.execchain.RetryExec execute
INFO: Retrying request to {}->http://my.ip.v6.only.host
java.net.NoRouteToHostException: No route to host
    at java.net.PlainSocketImpl.socketConnect(Native Method)
    at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:339)
    at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:200)
    at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:182)
    at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
    at java.net.Socket.connect(Socket.java:579)
    at org.apache.http.conn.socket.PlainConnectionSocketFactory.connectSocket(PlainConnectionSocketFactory.java:72)
    at org.apache.http.impl.conn.HttpClientConnectionOperator.connect(HttpClientConnectionOperator.java:123)
    at org.apache.http.impl.conn.PoolingHttpClientConnectionManager.connect(PoolingHttpClientConnectionManager.java:318)
    at org.apache.http.impl.execchain.MainClientExec.establishRoute(MainClientExec.java:363)
    at org.apache.http.impl.execchain.MainClientExec.execute(MainClientExec.java:219)
    at org.apache.http.impl.execchain.ProtocolExec.execute(ProtocolExec.java:195)
    at org.apache.http.impl.execchain.RetryExec.execute(RetryExec.java:86)
    at org.apache.http.impl.execchain.RedirectExec.execute(RedirectExec.java:108)
    at org.apache.http.impl.client.InternalHttpClient.doExecute(InternalHttpClient.java:184)
    at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:82)
    at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:106)
    at MainTest.main(MainTest.java:25)

java v1.7.0_65和v1.8.0_40,MacOS 10.10.2上出现了问题.在以前的版本MacOS 10.9.5上,它运行良好.

这是怎么回事？如何可以通过curljava 访问主机并且无法访问主机.

此外,我试图玩-Djava.net.preferIPv6Addresses=true,-Djava.net.preferIPv4Stack=false并且它无能为力.

UPD在OpenJDK,JDK-8015415中发现了一个相关的错误

UPD 2,当我尝试使用有线连接而不是wifi时,它帮助了我.奇怪的.

Answer 1

这可能是AirDrop + Java合作中的问题.

简短回答 - 尝试:

$ sudo ifconfig awdl0 down

调查下面的问题(感谢Sergey Shinderuk):

我们在java中有这样的代码来重现:

import java.net.Socket;

public class Test {
    public static void main(String[] args) throws Exception {
        new Socket("2a02:6b8::3", 80); // ya.ru
    }
}

当我们使用WiFi时,获得异常: java.net.NoRouteToHostException: No route to host

虽然使用telnet都可以:

$ telnet 2a02:6b8::3 80
Trying 2a02:6b8::3...
Connected to www.yandex.ru.
Escape character is '^]'.
^C

当我们关闭wifi,并使用有线连接 - 一切都好.但是,如果我们使用有线连接,但打开了wifi - 这个java代码将无法正常工作.这很奇怪.

我们需要比较connect(2)java和telnet之间的参数.

$ sudo dtrace -qn 'syscall::connect:entry { print(*(struct sockaddr_in6 *)copyin(arg1, arg2)) }' -c './telnet 2a02:6b8::3 80'

struct sockaddr_in6 {
    __uint8_t sin6_len = 0x1c
    sa_family_t sin6_family = 0x1e
    in_port_t sin6_port = 0x5000
    __uint32_t sin6_flowinfo = 0
    struct in6_addr sin6_addr = {
        union __u6_addr = {
            __uint8_t [16] __u6_addr8 = [ 0x2a, 0x2, 0x6, 0xb8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x3 ]
            __uint16_t [8] __u6_addr16 = [ 0x22a, 0xb806, 0, 0, 0, 0, 0, 0x300 ]
            __uint32_t [4] __u6_addr32 = [ 0xb806022a, 0, 0, 0x3000000 ]
        }
    }
    __uint32_t sin6_scope_id = 0
}

你可以看到我们已经打印了第二个connect(2)as struct 参数sockaddr_in6.您还可以看到所有预期的信息:AF_INET6,端口80和ipv6-address.

请注意:我们已启动./telnet,而不是telnet- dtrace无法使用Apple签署的系统二进制文件.所以我们应该复制它.

对于java也是如此:

$ sudo dtrace -qn 'syscall::connect:entry { print(*(struct sockaddr_in6 *)copyin(arg1, arg2)) }' -c '/Library/Java/JavaVirtualMachines/jdk1.8.0_65.jdk/Contents/Home/bin/java Test'
[...]
struct sockaddr_in6 {
    __uint8_t sin6_len = 0
    sa_family_t sin6_family = 0x1e
    in_port_t sin6_port = 0x5000
    __uint32_t sin6_flowinfo = 0
    struct in6_addr sin6_addr = {
        union __u6_addr = {
            __uint8_t [16] __u6_addr8 = [ 0x2a, 0x2, 0x6, 0xb8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x3 ]
            __uint16_t [8] __u6_addr16 = [ 0x22a, 0xb806, 0, 0, 0, 0, 0, 0x300 ]
            __uint32_t [4] __u6_addr32 = [ 0xb806022a, 0, 0, 0x3000000 ]
        }
    }
    __uint32_t sin6_scope_id = 0x8
}

我们可以看到,主要区别在于telnet发送sin6_len == 0但是java - sin6_scope_id = 0x8.确切的主要问题sin6_scope_id.telnet和curl发送scope_id == 0,但java - 0x8.当我们使用有线连接时,java发送scope_id == 0xb.

为了清楚起见,我们尝试scope_id用telnet 重现问题.使用WiFi做:

$ telnet 2a02:6b8::3%0 80
Trying 2a02:6b8::3...
Connected to www.yandex.ru.

$ telnet 2a02:6b8::3%8 80
Trying 2a02:6b8::3...
telnet: connect to address 2a02:6b8::3: No route to host
telnet: Unable to connect to remote host

$ telnet 2a02:6b8::3%b 80
Trying 2a02:6b8::3...
Connected to www.yandex.ru.

所以telnet可以连接0xb,但不能与0x8.

似乎java的这个代码的正确位置是:http: //hg.openjdk.java.net/jdk8u/jdk8u/jdk/file/8fe85977d5a6/src/solaris/native/java/net/net_util_md.c#l105

我们已经看到scope_id了私有字段java.net.NetworkInterface.defaultIndex的值,它包含一些默认接口的索引.

我们可以用代码打印所有索引:

import java.lang.reflect.Field;
import java.net.NetworkInterface;
import java.util.Collections;
import java.util.List;

public class Test {
    public static void main(String[] args) throws Exception {
        List<NetworkInterface> netins = Collections.list(NetworkInterface.getNetworkInterfaces());
        for (NetworkInterface netin : netins) {
            System.out.println(netin + " " + netin.getIndex());
        }

        Field f = NetworkInterface.class.getDeclaredField("defaultIndex");
        f.setAccessible(true);
        System.out.println("defaultIndex = " + f.get(NetworkInterface.class));
    }
}

在wifi上:

$ java Netif
name:awdl0 (awdl0) 8
name:en0 (en0) 4
name:lo0 (lo0) 1
defaultIndex = 8

有线

$ java Netif
name:en4 (en4) 11
name:lo0 (lo0) 1
defaultIndex = 11

在有线+无线上

$ java Netif
name:awdl0 (awdl0) 8
name:en4 (en4) 11
name:en0 (en0) 4
name:lo0 (lo0) 1
defaultIndex = 8

当wifi连接时defaultIndex == 8,默认接口是awdl0.

所以我们只是

$ sudo ifconfig awdl0 down

和java代码的工作原理.

也:

• WiFriedX可以提供帮助.

• 另一个问题:https://bugs.openjdk.java.net/browse/JDK-8132520

• 什么是awd:什么是AWDL(Apple Wireless Direct Link)以及它是如何工作的？

Answer 2

这个补丁的作者是https://github.com/snaury.

说明:

你需要用otool打开libnet.dylib并找到_setDefaultScopeID符号:

otool -tv -p _setDefaultScopeID libnet.dylib

在这里你可以找到与0和条件跳转的比较:

000000000000b882    cmpb    $0x1e, 0x1(%r14)
000000000000b887    jne 0xb8aa
000000000000b889    cmpl    $0x0, 0x18(%r14)
000000000000b88e    jne 0xb8aa

您需要使用任何十六进制编辑器将条件跳转替换为无条件跳转:

000000000000b882    cmpb    $0x1e, 0x1(%r14)
000000000000b887    jne 0xb8aa
000000000000b889    cmpl    $0x0, 0x18(%r14)
000000000000b88e    jmp 0xb8aa

JNE == 75 1a
JMP == eb 1a

或者使用这一行命令:

otool -tv -p _setDefaultScopeID libnet.dylib | awk '/cmpl.*\$0x0/ {print $1}' | python -c 'exec """\nwith open("libnet.dylib", "r+b") as fd:\n    fd.seek(int(raw_input(), 16) + 5)\n    fd.write(chr(235))\n"""'