[libvirt-users] Retrieving datas sent by host within the Guest

[Jean-Pierre Ribeauville]

Hi,

The guest is waiting a connect from the host and then tries to read what has been sent by the host.

Both Guest and Host codes look like that :

main()
{
     int sock, msgsock, rval;
     struct sockaddr_un server;
     char buf[1024];


    sock = socket(AF_UNIX, SOCK_STREAM, 0);
    if (sock < 0) {
        perror("opening stream socket");
        exit(1);
     }
     server.sun_family = AF_UNIX;
     strcpy(server.sun_path, NAME);
     if (bind(sock, (struct sockaddr *) &server, sizeof(struct sockaddr_un))) {
         perror("binding stream socket");
         exit(1);
     }
     printf("Socket has name %s\n", server.sun_path);
     listen(sock, 5);
     for (;;) {
         msgsock = accept(sock, 0, 0);
         if (msgsock == -1)
             perror("accept");
         else do {
             bzero(buf, sizeof(buf));
             if ((rval = read(msgsock, buf, 1024)) < 0)


on the host side :

main(argc, argv)
     ....

     sock = socket(AF_UNIX, SOCK_STREAM | SOCK_NONBLOCK, 0);
     if (sock < 0) {
         perror("opening stream socket");
         return(1);
     }
     server.sun_family = AF_UNIX;
     strcpy(server.sun_path, argv[1]);

     

     if (connect(sock, (struct sockaddr *) &server, sizeof(struct sockaddr_un)) < 0) {
         close(sock);
         perror("connecting stream socket");
         return(1);
     }
     if (write(sock, buffer, strlen(buffer)) < 0)
         perror("writing on stream socket");

Even if the host is not opening or sending anything I got this "already in use" error message.


Regards,

J.P.

-----Message d'origine-----
De : Martin Kletzander [mailto:mkletzan at redhat.com] 
Envoyé : mercredi 4 novembre 2015 16:21
À : Jean-Pierre Ribeauville
Cc : libvirt-users at redhat.com
Objet : Re: [libvirt-users] Retrieving datas sent by host within the Guest

On Wed, Nov 04, 2015 at 02:38:43PM +0000, Jean-Pierre Ribeauville wrote:
>Hi,
>
>I' trying to read datas sent by my KVM host within the Guest.
>Host send these datas trough a channel UNIX type , by using AF_UNIX socket stuff.
>
>If i try to retrive the datas by using such type of thing in the Guest :
>
>
>#define NAME "/dev/virtio-ports/agent"
>
>sock = socket(AF_UNIX, SOCK_STREAM, 0);
>12     if (sock < 0) {
>13         perror("opening stream socket");
>14         exit(1);
>15     }
>16     server.sun_family = AF_UNIX;
>17     strcpy(server.sun_path, NAME);
>18     if (bind(sock, (struct sockaddr *) &server, sizeof(struct sockaddr_un))) {
>19         perror("binding stream socket");
>20         exit(1);
>21     }
>
>
>I got  ""binding stream socket Address already in use"   when trying to bind the socket .
>

shouldn't you conect() instead of bind() ?  Of course, open() should write as well.

>
>But If I use such kind of thing :
>
>    fd = open("/dev/virtio-ports/agent", O_RDWR | O_NONBLOCK);
>    ssize_t size = read(fd, &rcv_buffer, 100);
>    if(size >0) printf("Read length(%d)  %s\n", size, rcv_buffer);
>
>It works fine.
>
>Is there any chance to be able to use socket stuff on Guest side or is there anything  I misunderstand?
>
>Thanks for help.
>
>
>J.P.
>
>
>J.P. Ribeauville
>
>
>P: +33.(0).1.47.17.20.49
>.
>Puteaux 3 Etage 5  Bureau 4
>
>jpribeauville at axway.com<mailto:jpribeauville at axway.com>
>http://www.axway.com<http://www.axway.com/>
>
>
>
>P Pensez à l'environnement avant d'imprimer.
>
>
>

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