[zeromq-dev] getpeername() couldn't resolve the peer address with underlying fd achieved from zmq_socket_monitor ZMQ_EVENT_ACCEPTED event?

Simon.Giesecke at btc-ag.com Simon.Giesecke at btc-ag.com
Wed Oct 24 12:13:27 CEST 2018


Hi,

I don't know if this solves the problem, but you must initialize peer_len with sizeof(peer_addr) before calling getpeername.

Also, it is possible that the peer address is not an IPv4 address. You should better use sockaddr_storage instead of sockaddr_in and check peer_addr.ss_family.

Best regards
Simon

-----Ursprüngliche Nachricht-----
Von: zeromq-dev <zeromq-dev-bounces at lists.zeromq.org> Im Auftrag von Yan, Liming (NSB - CN/Hangzhou)
Gesendet: Mittwoch, 24. Oktober 2018 04:25
An: zeromq-dev at lists.zeromq.org
Betreff: Re: [zeromq-dev] getpeername() couldn't resolve the peer address with underlying fd achieved from zmq_socket_monitor ZMQ_EVENT_ACCEPTED event?

HI,
   Could anybody respond to this issue?  

BR
Yan Limin


_____________________________________________
From: Yan, Liming (NSB - CN/Hangzhou) 
Sent: Tuesday, October 16, 2018 4:49 PM
To: 'zeromq-dev at lists.zeromq.org' <zeromq-dev at lists.zeromq.org>
Subject: getpeername() couldn't resolve the peer address with underlying fd achieved from zmq_socket_monitor ZMQ_EVENT_ACCEPTED event?


Hi,
   I created a monitor on a router socket and monitor the ZMQ_EVENT_ACCEPTED event. Each time when a new client accepted, I can get the event and underlying fd. The code is just as the example in page https://emea01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fapi.zeromq.org%2F4-1%3Azmq-socket-monitor&data=02%7C01%7Csimon.giesecke%40btc-ag.com%7Ccb41745a80fc4815d0d808d63957f56e%7Cc064efb078954eebb406a40bc377bc7d%7C0%7C0%7C636759447274350077&sdata=a0%2BSyH05OinbAGsIx5whElJ9d%2FlMqDA4LEaiq4AA8jE%3D&reserved=0 . Then I need to use getpeername to know who is the peer ip address.  But this seems not work. I can only get 0.0.0.0.  Does this underlying fd provided by monitor support getpeername()? Or anything wrong with me?  Thanks.

{
        char ip[128];
        struct sockaddr_in peer_addr;
        unsigned int peer_len;
        int ret, fd = (int)monitor_event->value;

        ret = getpeername(fd, (struct sockaddr *)&peer_addr, &peer_len);
        if (ret == -1) {
            printf("Get peer name failed. fd=%d. err=%d:%s.\n", fd, errno, strerror(errno));
        }
        else {
            inet_ntop(AF_INET, &peer_addr.sin_addr, ip, sizeof(ip));
            printf("New client accepted: %s:%d. Local socket:%s. fd=%d.\n", ip, ntohs(peer_addr.sin_port),
                         monitor_event->socket_addr, fd);
        }
}
   New client accepted: 0.0.0.0:29186. Local socket:tcp://169.254.0.10:48000. fd=34.

ZMQ_EVENT_ACCEPTED
The socket has accepted a connection from a remote peer. The event value is the FD of the underlying network socket. Warning: there is no guarantee that the FD is still valid by the time your code receives this event.



BR
Yan Limin


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