CMQ消费者报错，无法获取本机ip地址问题排查

 public static InetAddress getLocalHost() throws UnknownHostException {

        SecurityManager security = System.getSecurityManager();
        try {
            // 1.获取hotname，这是个native方法，hotspot中实现非常简单，
            直接系统调用gethostname，如果调用失败，那么获取硬编码值‘localhost’
            String local = impl.getLocalHostName();

            if (security != null) {
                security.checkConnect(local, -1);
            }

            if (local.equals("localhost")) {
                return impl.loopbackAddress();
            }

            InetAddress ret = null;
            synchronized (cacheLock) {
                long now = System.currentTimeMillis();
                // 2. 如果命中cachedLocalHost，直接用缓存值
                if (cachedLocalHost != null) {
                    if ((now - cacheTime) < maxCacheTime) // Less than 5s old?
                        ret = cachedLocalHost;
                    else
                        cachedLocalHost = null;
                }

                // we are calling getAddressesFromNameService directly
                // to avoid getting localHost from cache
                if (ret == null) {
                    InetAddress[] localAddrs;
                    try {
                        // 3. 下面的逻辑是去缓存或者系统调用获取地址
                        localAddrs =
                                InetAddress.getAddressesFromNameService(local, null);
                    } catch (UnknownHostException uhe) {
                        // Rethrow with a more informative error message.
                        UnknownHostException uhe2 =
                                new UnknownHostException(local + ": " +
                                        uhe.getMessage());
                        uhe2.initCause(uhe);
                        throw uhe2;
                    }
                    cachedLocalHost = localAddrs[0];
                    cacheTime = now;
                    ret = localAddrs[0];
                }
            }
            return ret;
        } catch (java.lang.SecurityException e) {
            return impl.loopbackAddress();
        }
    }

/*
 * Find an internet address for a given hostname.  Note that this
 * code only works for addresses of type INET. The translation
 * of %d.%d.%d.%d to an address (int) occurs in java now, so the
 * String "host" shouldn't *ever* be a %d.%d.%d.%d string
 *
 * Class:     java_net_Inet4AddressImpl
 * Method:    lookupAllHostAddr
 * Signature: (Ljava/lang/String;)[[B
 */

JNIEXPORT jobjectArray JNICALL
Java_java_net_Inet4AddressImpl_lookupAllHostAddr(JNIEnv *env, jobject this,
                                                jstring host) {
    ...
    ...
    // 系统调用
    error = getaddrinfo(hostname, NULL, &hints, &res);

    if (error) {
        /* report error */
        ThrowUnknownHostExceptionWithGaiError(env, hostname, error);
        JNU_ReleaseStringPlatformChars(env, host, hostname);
        return NULL;
    } else {
        ....
    }
    ...
}

#include <stdlib.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <string.h>
#include <stdio.h>
#include <arpa/inet.h>

int main(int argc, char **argv)
{
    int ret = -1;
    struct addrinfo *res;
    struct addrinfo hint;
    struct addrinfo *curr;
    char ipstr[16];   

    if (argc != 2) {
        printf("parameter error\n");
        return -1;
    }

    bzero(&hint, sizeof(hint));
    hint.ai_family = AF_INET;
    hint.ai_socktype = SOCK_STREAM;

    ret = getaddrinfo(argv[1], NULL, &hint, &res);
     printf("getaddrinfo finish\n");
    if (ret != 0) 
    {
        printf("getaddrinfo error\n");
        return -1;
    }

    for (curr = res; curr != NULL; curr = curr->ai_next) 
    {
        inet_ntop(AF_INET,&(((struct sockaddr_in *)(curr->ai_addr))->sin_addr), ipstr, 16);
        printf("%s\n", ipstr);
    }

    freeaddrinfo(res);

    return 0;
}

...
...
open("/lib64/libresolv.so.2", O_RDONLY|O_CLOEXEC) = 3
open("/etc/host.conf", O_RDONLY|O_CLOEXEC) = 3
open("/etc/resolv.conf", O_RDONLY|O_CLOEXEC) = 3
open("/etc/nsswitch.conf", O_RDONLY|O_CLOEXEC) = 3
open("/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
open("/lib64/libnss_files.so.2", O_RDONLY|O_CLOEXEC) = 3
open("/etc/hosts", O_RDONLY|O_CLOEXEC)  = 3
open("/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
...
open("/lib64/libnss_dns.so.2", O_RDONLY|O_CLOEXEC) = 3
...
uname({sysname="Linux", nodename="efg", ...}) = 0
socket(AF_NETLINK, SOCK_RAW|SOCK_CLOEXEC|SOCK_NONBLOCK, NETLINK_ROUTE) = 3
setsockopt(3, SOL_SOCKET, SO_PASSCRED, [1], 4) = 0
setsockopt(3, SOL_NETLINK, 3, [1], 4)   = 0
bind(3, {sa_family=AF_NETLINK, pid=0, groups=00000000}, 16) = 0
getsockname(3, {sa_family=AF_NETLINK, pid=8933, groups=00000000}, [12]) = 0
sendto(3, "\x18\x00\x00\x00\x16\x00\x05\x03\x01\x00\x00\x00\x00\x00\x00\x00\x02\x20\x00\x00\x00\x00\x00\x00", 24, 0, {sa_family=AF_NETLINK, pid=0, groups=00000000}, 16) = 24
clock_gettime(CLOCK_MONOTONIC, {63428, 128822240}) = 0
recvmsg(3, {msg_name(0)=NULL, msg_iov(1)=[{NULL, 0}], msg_controllen=56, [{cmsg_len=20, cmsg_level=SOL_NETLINK, cmsg_type=3}, {cmsg_len=28, cmsg_level=SOL_SOCKET, cmsg_type=SCM_CREDENTIALS, {pid=0, uid=0, gid=0}}], msg_flags=MSG_TRUNC}, MSG_PEEK|MSG_TRUNC) = 164
recvmsg(3, {msg_name(0)=NULL, msg_iov(1)=[{"\x4c\x00\x00\x00\x14\x00\x02\x00\x01\x00\x00\x00\xe5\x22\x00\x00\x02\x08\x80\xfe\x01\x00\x00\x00\x08\x00\x01\x00\x7f\x00\x00\x01"..., 328}], msg_controllen=56, [{cmsg_len=20, cmsg_level=SOL_NETLINK, cmsg_type=3}, {cmsg_len=28, cmsg_level=SOL_SOCKET, cmsg_type=SCM_CREDENTIALS, {pid=0, uid=0, gid=0}}], msg_flags=0}, MSG_TRUNC) = 164
clock_gettime(CLOCK_MONOTONIC, {63428, 128967588}) = 0
...

public static InetAddress getLocalHostExactAddress() {
    try {
        InetAddress candidateAddress = null;

        Enumeration<NetworkInterface> networkInterfaces = NetworkInterface.getNetworkInterfaces();
        while (networkInterfaces.hasMoreElements()) {
            NetworkInterface iface = networkInterfaces.nextElement();
            // 该网卡接口下的ip会有多个，也需要一个个的遍历，找到自己所需要的
            for (Enumeration<InetAddress> inetAddrs = iface.getInetAddresses(); inetAddrs.hasMoreElements(); ) {
                InetAddress inetAddr = inetAddrs.nextElement();
                // 排除loopback回环类型地址（不管是IPv4还是IPv6 只要是回环地址都会返回true）
                if (!inetAddr.isLoopbackAddress()) {
                    if (inetAddr.isSiteLocalAddress()) {
                        // 如果是site-local地址，就是它了 就是我们要找的
                        // ~~~~~~~~~~~~~绝大部分情况下都会在此处返回你的ip地址值~~~~~~~~~~~~~
                        return inetAddr;
                    }

                    // 若不是site-local地址 那就记录下该地址当作候选
                    if (candidateAddress == null) {
                        candidateAddress = inetAddr;
                    }

                }
            }
        }

        // 如果出去loopback回环地之外无其它地址了，那就回退到原始方案吧
        return candidateAddress == null ? InetAddress.getLocalHost() : candidateAddress;
    } catch (Exception e) {
        e.printStackTrace();
    }
    return null;
}