Implement dynamic port allocation to avoid conflicts

Fixes anthropics#147

Implement dynamic port allocation to avoid conflicts with reserved ports.

* **computer-use-demo/image/x11vnc_startup.sh**
  - Add functions to check port availability and find an available port.
  - Dynamically assign the VNC server port instead of hardcoding port 5900.
  - Update the `netstat` command to use the dynamically assigned port.

* **computer-use-demo/image/novnc_startup.sh**
  - Add functions to check port availability and find an available port.
  - Dynamically assign the VNC server port instead of hardcoding port 5900.
  - Modify the `--vnc` option to use the dynamic port.

* **computer-use-demo/image/port_check.sh**
  - Create a script to check port availability.
  - Use `lsof` to check if a port is in use.
  - Return an available port if the specified one is in use.

* **computer-use-demo/.ports**
  - Maintain a list of reserved ports.
  - Include common ports used by macOS and other systems.

---

For more details, open the [Copilot Workspace session](https://copilot-workspace.githubnext.com/anthropics/anthropic-quickstarts/issues/147?shareId=XXXX-XXXX-XXXX-XXXX).

computer-use-demo/.ports

@@ -0,0 +1,9 @@
+# Reserved Ports List
+# This file contains a list of ports that are reserved and should not be used by the application.
+
+# Common ports used by macOS and other systems
+5900  # VNC
+22    # SSH
+80    # HTTP
+443   # HTTPS
+3389  # RDP

computer-use-demo/image/novnc_startup.sh

@@ -1,9 +1,31 @@
 #!/bin/bash
 echo "starting noVNC"
 
+# Function to check port availability
+check_port() {
+    local port=$1
+    if lsof -i :$port >/dev/null 2>&1; then
+        return 1  # Port is in use
+    else
+        return 0  # Port is available
+    fi
+}
+
+# Find an available port starting from 5900
+find_available_port() {
+    local port=5900
+    while ! check_port $port; do
+        ((port++))
+    done
+    echo $port
+}
+
+# Dynamically assign the VNC server port
+VNC_PORT=$(find_available_port)
+
 # Start noVNC with explicit websocket settings
 /opt/noVNC/utils/novnc_proxy \
-    --vnc localhost:5900 \
+    --vnc localhost:$VNC_PORT \
     --listen 6080 \
     --web /opt/noVNC \
     > /tmp/novnc.log 2>&1 &

computer-use-demo/image/port_check.sh

@@ -0,0 +1,31 @@
+#!/bin/bash
+
+# Function to check if a port is in use
+check_port() {
+    local port=$1
+    if lsof -i :$port >/dev/null 2>&1; then
+        return 1  # Port is in use
+    else
+        return 0  # Port is available
+    fi
+}
+
+# Function to find an available port starting from a given port
+find_available_port() {
+    local start_port=$1
+    local port=$start_port
+    while ! check_port $port; do
+        ((port++))
+    done
+    echo $port
+}
+
+# Main script
+if [ $# -ne 1 ]; then
+    echo "Usage: $0 <start_port>"
+    exit 1
+fi
+
+start_port=$1
+available_port=$(find_available_port $start_port)
+echo $available_port

computer-use-demo/image/x11vnc_startup.sh

@@ -1,11 +1,33 @@
 #!/bin/bash
 echo "starting vnc"
 
+# Function to check port availability
+check_port() {
+    local port=$1
+    if lsof -i :$port >/dev/null 2>&1; then
+        return 1  # Port is in use
+    else
+        return 0  # Port is available
+    fi
+}
+
+# Find an available port starting from 5900
+find_available_port() {
+    local port=5900
+    while ! check_port $port; do
+        ((port++))
+    done
+    echo $port
+}
+
+# Dynamically assign the VNC server port
+VNC_PORT=$(find_available_port)
+
 (x11vnc -display $DISPLAY \
     -forever \
     -shared \
     -wait 50 \
-    -rfbport 5900 \
+    -rfbport $VNC_PORT \
     -nopw \
     2>/tmp/x11vnc_stderr.log) &
 
@@ -14,7 +36,7 @@ x11vnc_pid=$!
 # Wait for x11vnc to start
 timeout=10
 while [ $timeout -gt 0 ]; do
-    if netstat -tuln | grep -q ":5900 "; then
+    if netstat -tuln | grep -q ":$VNC_PORT "; then
         break
     fi
     sleep 1