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

[Gerd Hoffmann <kraxel@redhat.com>]

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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