Re: [Qemu-devel] [PATCH] starting qemu vnc session on a pre-allocated port

[Anthony Liguori]

Shahar Livne wrote:
> Hi,
>
> I am working on a project that runs many concurrent qemu sessions with 
> vnc.
> Handling the vnc ports for the different sessions is an issue that 
> also project like qemudo tries to solve.
> The solution chosen there was to handle a pool of ports and manage 
> them internally.
> Such a solution ignores the fact that these ports may be occupied by 
> other processes on the same OS, and it actually duplicates an OS task.
> A solution that uses external port handling facility (like a native OS 
> free ports selection), by using a pre-allocated port is suggested.
>
> Currently there is the following vnc option:
> -vnc display    [start a VNC server on display]
>
> Adding the following option:
> -vnc-socket sd  [force VNC server on an already opened Socket Descriptor]

Just redirect each port to a unique unix domain socket and then you can 
forward traffic to TCP sockets to your heart's content.

Regards,

Anthony Liguori

> overrides the new socket opening for the vnc on 5900+display port, and 
> uses the given sd socket descriptor instead.
>
> In this way, one can create a socket, bind it to any specific port 
> (e.g. arbitrary free port given by the OS), and only then start the 
> qemu with the socket descriptor. Doing this, all the ports accounting 
> is done by the OS.
>
> The patch is against cvs 2007-06-21, but I think nothing relevant has 
> changed since.
>
> Comments are welcome,
> Shahar
> ------------------------------------------------------------------------
>
> Index: vnc.c
> ===================================================================
> --- vnc.c       (revision 6)
> +++ vnc.c       (revision 8)
> @@ -59,6 +59,7 @@
>      QEMUTimer *timer;
>      int lsock;
>      int csock;
> +    int fsock;
>      DisplayState *ds;
>      int need_update;
>      int width;
> @@ -99,9 +100,14 @@
>      if (vnc_state == NULL)
>         term_printf("VNC server disabled\n");
>      else {
> -       term_printf("VNC server active on: ");
> -       term_print_filename(vnc_state->display);
> -       term_printf("\n");
> +       if (vnc_state->fsock == -1) {
> +           term_printf("VNC server active on: ");
> +           term_print_filename(vnc_state->display);
> +           term_printf("\n");
> +       } else {
> +           term_printf("VNC server active on socket descriptor: %d", 
> vnc_state->fsock);
> +           term_printf("\n");
> +       }
>  
>  	if (vnc_state->csock == -1)
>             term_printf("No client connected\n");
> @@ -1169,7 +1175,7 @@
>  
>  extern int parse_host_port(struct sockaddr_in *saddr, const char *str);
>  
> -void vnc_display_init(DisplayState *ds, const char *arg)
> +void vnc_display_init(DisplayState *ds, const char *arg, int forced_vnc_socket)
>  {
>      struct sockaddr *addr;
>      struct sockaddr_in iaddr;
> @@ -1191,6 +1197,7 @@
>  
>      vs->lsock = -1;
>      vs->csock = -1;
> +    vs->fsock = forced_vnc_socket;
>      vs->depth = 4;
>      vs->last_x = -1;
>      vs->last_y = -1;
> @@ -1213,60 +1220,67 @@
>  
>      vnc_dpy_resize(vs->ds, 640, 400);
>  
> -#ifndef _WIN32
> -    if (strstart(arg, "unix:", &p)) {
> -       addr = (struct sockaddr *)&uaddr;
> -       addrlen = sizeof(uaddr);
> -
> -       vs->lsock = socket(PF_UNIX, SOCK_STREAM, 0);
> -       if (vs->lsock == -1) {
> -           fprintf(stderr, "Could not create socket\n");
> -           exit(1);
> -       }
> -
> -       uaddr.sun_family = AF_UNIX;
> -       memset(uaddr.sun_path, 0, 108);
> -       snprintf(uaddr.sun_path, 108, "%s", p);
>  
> -	unlink(uaddr.sun_path);
> -    } else
> +    if (vs->fsock == -1) {
> +#ifndef _WIN32
> +        if (strstart(arg, "unix:", &p)) {
> +            addr = (struct sockaddr *)&uaddr;
> +            addrlen = sizeof(uaddr);
> +     
> +            vs->lsock = socket(PF_UNIX, SOCK_STREAM, 0);
> +            if (vs->lsock == -1) {
> +                fprintf(stderr, "Could not create socket\n");
> +                exit(1);
> +            }
> +     
> +            uaddr.sun_family = AF_UNIX;
> +            memset(uaddr.sun_path, 0, 108);
> +            snprintf(uaddr.sun_path, 108, "%s", p);
> +     
> +            unlink(uaddr.sun_path);
> +        } else
>  #endif
> -    {
> -       addr = (struct sockaddr *)&iaddr;
> -       addrlen = sizeof(iaddr);
> -
> -       vs->lsock = socket(PF_INET, SOCK_STREAM, 0);
> -       if (vs->lsock == -1) {
> -           fprintf(stderr, "Could not create socket\n");
> -           exit(1);
> -       }
> -
> -       if (parse_host_port(&iaddr, arg) < 0) {
> -           fprintf(stderr, "Could not parse VNC address\n");
> -           exit(1);
> -       }
> -	    
> -	iaddr.sin_port = htons(ntohs(iaddr.sin_port) + 5900);
> -
> -       reuse_addr = 1;
> -       ret = setsockopt(vs->lsock, SOL_SOCKET, SO_REUSEADDR,
> -                        (const char *)&reuse_addr, sizeof(reuse_addr));
> -       if (ret == -1) {
> -           fprintf(stderr, "setsockopt() failed\n");
> -           exit(1);
> -       }
> -    }
> -
> -    if (bind(vs->lsock, addr, addrlen) == -1) {
> -       fprintf(stderr, "bind() failed\n");
> -       exit(1);
> -    }
> +        {
> +            addr = (struct sockaddr *)&iaddr;
> +            addrlen = sizeof(iaddr);
> +     
> +            vs->lsock = socket(PF_INET, SOCK_STREAM, 0);
> +            if (vs->lsock == -1) {
> +                fprintf(stderr, "Could not create socket\n");
> +                exit(1);
> +            }
> +     
> +            if (parse_host_port(&iaddr, arg) < 0) {
> +                fprintf(stderr, "Could not parse VNC address\n");
> +                exit(1);
> +            }
> +                
> +            iaddr.sin_port = htons(ntohs(iaddr.sin_port) + 5900);
> +     
> +            reuse_addr = 1;
> +            ret = setsockopt(vs->lsock, SOL_SOCKET, SO_REUSEADDR,
> +                        (const char *)&reuse_addr, sizeof(reuse_addr));
> +            if (ret == -1) {
> +                fprintf(stderr, "setsockopt() failed\n");
> +                exit(1);
> +            }
> +        }
> +     
> +        if (bind(vs->lsock, addr, addrlen) == -1) {
> +            fprintf(stderr, "bind() failed\n");
> +            exit(1);
> +        }
> +     
> +        if (listen(vs->lsock, 1) == -1) {
> +            fprintf(stderr, "listen() failed\n");
> +            exit(1);
> +        }
>  
> -    if (listen(vs->lsock, 1) == -1) {
> -       fprintf(stderr, "listen() failed\n");
> -       exit(1);
> +    } else {
> +        vs->lsock = vs->fsock;
> +       fprintf(stdout, "using forced socket %d\n",vs->fsock);
>      }
> -
> +    
>      ret = qemu_set_fd_handler2(vs->lsock, vnc_listen_poll, vnc_listen_read, NULL, vs);
>      if (ret == -1) {
>         exit(1);
> Index: vl.c
> ===================================================================
> --- vl.c        (revision 6)
> +++ vl.c        (revision 8)
> @@ -178,6 +178,7 @@
>  static VLANState *first_vlan;
>  int smp_cpus = 1;
>  const char *vnc_display;
> +int vnc_socket = -1;
>  #if defined(TARGET_SPARC)
>  #define MAX_CPUS 16
>  #elif defined(TARGET_I386)
> @@ -6651,6 +6652,7 @@
>             "-no-reboot      exit instead of rebooting\n"
>             "-loadvm file    start right away with a saved state (loadvm in 
> monitor)\n"
>            "-vnc display    start a VNC server on display\n"
> +          "-vnc-socket sd  force VNC server on an already opened Socket 
> Descriptor\n"
>  #ifndef _WIN32
>            "-daemonize      daemonize QEMU after initializing\n"
>  #endif
> @@ -6745,6 +6747,7 @@
>      QEMU_OPTION_usbdevice,
>      QEMU_OPTION_smp,
>      QEMU_OPTION_vnc,
> +    QEMU_OPTION_vnc_socket,
>      QEMU_OPTION_no_acpi,
>      QEMU_OPTION_no_reboot,
>      QEMU_OPTION_show_cursor,
> @@ -6836,6 +6839,7 @@
>      { "usbdevice", HAS_ARG, QEMU_OPTION_usbdevice },
>      { "smp", HAS_ARG, QEMU_OPTION_smp },
>      { "vnc", HAS_ARG, QEMU_OPTION_vnc },
> +    { "vnc-socket", HAS_ARG, QEMU_OPTION_vnc_socket },
>  
>      /* temporary options */
>      { "usb", 0, QEMU_OPTION_usb },
> @@ -7588,6 +7592,18 @@
>             case QEMU_OPTION_vnc:
>                 vnc_display = optarg;
>                 break;
> +           case QEMU_OPTION_vnc_socket:
> +                {
> +                   int sd;
> +                    sd = atoi(optarg);
> +                   if (sd < 0) {
> +                       fprintf(stderr, "Bad argument to vnc socket 
> descriptor\n");
> +                       exit(1);
> +                   } else {
> +                       vnc_socket = sd;
> +                   }
> +                    break;
> +                }
>              case QEMU_OPTION_no_acpi:
>                  acpi_enabled = 0;
>                  break;
> @@ -7879,7 +7895,7 @@
>      if (nographic) {
>          /* nothing to do */
>      } else if (vnc_display != NULL) {
> -        vnc_display_init(ds, vnc_display);
> +        vnc_display_init(ds, vnc_display, vnc_socket);
>      } else {
>  #if defined(CONFIG_SDL)
>          sdl_display_init(ds, full_screen, no_frame);
> Index: vl.h
> ===================================================================
> --- vl.h        (revision 6)
> +++ vl.h        (revision 8)
> @@ -965,7 +965,7 @@
>  void cocoa_display_init(DisplayState *ds, int full_screen);
>  
>  /* vnc.c */
> -void vnc_display_init(DisplayState *ds, const char *display);
> +void vnc_display_init(DisplayState *ds, const char *display, int 
> forced_vnc_socket);
>  void do_info_vnc(void);
>  
>  /* x_keymap.c */
>