[Qemu-devel] [Patch] vnc: support vnc port auto-allocation

[Qemu-devel] [Patch] vnc: support vnc port auto-allocation

[Gerd Hoffmann]

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  Hi folks,

This patch makes qemu (optionally) find a free vnc display, using the
-vnc $host:$start,to=$end syntax as discussed on the list a few weeks ago.

cheers,
  Gerd

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>From 5c30379b58500c59d430d3257db65b33326adddf Mon Sep 17 00:00:00 2001
From: Gerd Hoffmann <kraxel@redhat.com>
Date: Fri, 24 Oct 2008 10:36:20 +0200
Subject: [PATCH] vnc: support vnc port auto-allocation.

This patch adds support for automatically allocating an unused vnc
display port.  It adds a to= option for vnc, specifying the upper
limit for the display number to try.  Scanning is started at the display
number given in the display specification, i.e. this command line:

    -vnc localhost:7,to=11

will try displays 7 to 11 (inclusive).

The display actually allocated can be queried using the "info vnc"
monitor command.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 vnc.c |   55 +++++++++++++++++++++++++++++++++++++++++++------------
 1 files changed, 43 insertions(+), 12 deletions(-)

diff --git a/vnc.c b/vnc.c
index 266460f..9d3c4a3 100644
--- a/vnc.c
+++ b/vnc.c
@@ -2303,16 +2303,16 @@ int vnc_display_open(DisplayState *ds, const char *display)
     const char *options;
     int password = 0;
     int reverse = 0;
+    int to_port = 0;
 #ifdef CONFIG_VNC_TLS
     int tls = 0, x509 = 0;
 #endif
 
     vnc_display_close(ds);
-    if (strcmp(display, "none") == 0)
-	return 0;
-
     if (!(vs->display = strdup(display)))
 	return -1;
+    if (strcmp(display, "none") == 0)
+	return 0;
 
     options = display;
     while ((options = strchr(options, ','))) {
@@ -2321,6 +2321,8 @@ int vnc_display_open(DisplayState *ds, const char *display)
 	    password = 1; /* Require password auth */
 	} else if (strncmp(options, "reverse", 7) == 0) {
 	    reverse = 1;
+	} else if (strncmp(options, "to=", 3) == 0) {
+            to_port = atoi(options+3) + 5900;
 #ifdef CONFIG_VNC_TLS
 	} else if (strncmp(options, "tls", 3) == 0) {
 	    tls = 1; /* Require TLS */
@@ -2416,6 +2418,14 @@ int vnc_display_open(DisplayState *ds, const char *display)
 
 	if (!reverse) {
 	    unlink(uaddr.sun_path);
+            if (bind(vs->lsock, addr, addrlen) == -1) {
+                fprintf(stderr, "bind() failed\n");
+                close(vs->lsock);
+                vs->lsock = -1;
+                free(vs->display);
+                vs->display = NULL;
+                return -1;
+            }
 	}
     } else
 #endif
@@ -2451,6 +2461,36 @@ int vnc_display_open(DisplayState *ds, const char *display)
 	    vs->display = NULL;
 	    return -1;
 	}
+
+        if (!reverse) {
+            if (to_port < 5900)
+                to_port = ntohs(iaddr.sin_port);
+            while (ntohs(iaddr.sin_port) <= to_port) {
+                if (bind(vs->lsock, addr, addrlen) == 0)
+                    break;
+                iaddr.sin_port = htons(ntohs(iaddr.sin_port) + 1);
+            }
+            if (ntohs(iaddr.sin_port) <= to_port) {
+                /* success: set vs->display so "info vnc" displays the actual port */
+                char *dpy, *opts, *h;
+                opts = strchr(vs->display,',');
+                h = strchr(vs->display, ':');
+                if (h)
+                    *h = 0;
+                dpy = qemu_malloc(256);
+                snprintf(dpy, 256, "%s:%d%s", h ? vs->display : "",
+                         ntohs(iaddr.sin_port) - 5900, opts);
+                qemu_free(vs->display);
+                vs->display = dpy;
+            } else {
+                fprintf(stderr, "didn't find free vnc display port\n");
+                close(vs->lsock);
+                vs->lsock = -1;
+                free(vs->display);
+                vs->display = NULL;
+                return -1;
+            }
+        }
     }
 
     if (reverse) {
@@ -2469,15 +2509,6 @@ int vnc_display_open(DisplayState *ds, const char *display)
         }
     }
 
-    if (bind(vs->lsock, addr, addrlen) == -1) {
-	fprintf(stderr, "bind() failed\n");
-	close(vs->lsock);
-	vs->lsock = -1;
-	free(vs->display);
-	vs->display = NULL;
-	return -1;
-    }
-
     if (listen(vs->lsock, 1) == -1) {
 	fprintf(stderr, "listen() failed\n");
 	close(vs->lsock);
-- 
1.5.5.1

[Qemu-devel] Re: [Patch] vnc: support vnc port auto-allocation

[Gerd Hoffmann]

  Hi,

> This patch makes qemu (optionally) find a free vnc display, using the
> -vnc $host:$start,to=$end syntax as discussed on the list a few weeks ago.

While being at it:  I'm consider doing something simliar for
serial/parallel device tcp redirections.  Needs the "info chardev"
monitor command patch sent earlier this week to be useful.  Probably
makes sense to factor out the free tcp port scan then.  And when being
busy hacking the networking code I'd might just make those bits ipv6
ready along the way.

Comments?

cheers,
  Gerd