Remove hardcoded port 8080 and replace with configurable port (#7)

This PR is:

* replacing the hardcoded port 8080 used by DHCP client backend with a configurable port, which defaults to 8967 (much less common than 8080 to make port conflicts less likely)
* improving hostname and MAC address validations on the addon configuration using regex

config.yaml

@@ -3,9 +3,9 @@
 # as reported by the Github Action workflow 'publish.yaml', so that you can force HomeAssistant
 # to use the docker image of that feature branch instead of the docker image of 'main', by pointing
 # HomeAssistant to that feature branch
-version: 1.1.0
-slug: dnsmasq-dhcp
-name: Dnsmasq-DHCP
+version: beta
+slug: dnsmasq-dhcp-beta
+name: Dnsmasq-DHCP BETA
 description: A DHCP server based on dnsmasq
 url: https://github.com/f18m/ha-addon-dnsmasq-dhcp-server/tree/main
 advanced: true
@@ -51,13 +51,17 @@ options:
     end_ip: 192.168.1.250
   ip_address_reservations: 
     - mac: aa:bb:cc:dd:ee:ff
-      name: "An important host with a static IP address assigned"
+      name: "An-important-host-with-reserved-IP"
       ip: 192.168.1.15
   dhcp_clients_friendly_names:
     - mac: dd:ee:aa:dd:bb:ee
       name: "This is a friendly name to label this host, even if it gets a dynamic IP"
   log_dhcp: true
   log_web_ui: false
+  # this addon uses "host_network: true" so the internal HTTP server will bind on the interface
+  # provided as network.interface and will occupy a port there; the following parameter makes
+  # that port configurable to avoid conflicts with other services
+  web_ui_port: 8976
 schema:
   default_lease: str
   address_reservation_lease: str
@@ -75,13 +79,16 @@ schema:
     end_ip: str
   ip_address_reservations:
     - ip: str
-      mac: str
-      name: str
+      mac: match(^([0-9A-Fa-f]{2}[:-]){5}([0-9A-Fa-f]{2})$)
+      # the name in this case must be a valid hostname as per RFC 1123 since it is passed to dnsmasq
+      # that will refuse to start if an invalid hostname format is used
+      name: match(^[a-zA-Z0-9\-.]*$)
   dhcp_clients_friendly_names:
-    - mac: str
+    - mac: match(^([0-9A-Fa-f]{2}[:-]){5}([0-9A-Fa-f]{2})$)
       name: str
   log_dhcp: bool
   log_web_ui: bool
+  web_ui_port: int
 startup: system
 privileged:
   - NET_ADMIN

dhcp-clients-webapp-backend/pkg/uibackend/uibackend.go

@@ -21,7 +21,6 @@ import (
 	"github.com/netdata/go.d.plugin/pkg/iprange"
 )
 
-var bindAddress = ":8080"
 var defaultDnsmasqLeasesFile = "/data/dnsmasq.leases"
 var defaultHomeAssistantConfigFile = "/data/options.json"
 var dnsmasqMarkerForMissingHostname = "*"
@@ -114,8 +113,9 @@ type UIBackend struct {
 	dhcpEndIP   net.IP
 
 	// the actual HTTP server
-	server   http.Server
-	upgrader websocket.Upgrader
+	serverPort int
+	server     http.Server
+	upgrader   websocket.Upgrader
 
 	// map of connected websockets
 	clients     map[*websocket.Conn]bool
@@ -125,10 +125,10 @@ type UIBackend struct {
 	dhcpClientData     []DhcpClientData
 	dhcpClientDataLock sync.Mutex
 
-	// ch used to broadcast tabular data from backend->frontend
+	// channel used to broadcast tabular data from backend->frontend
 	broadcastCh chan []DhcpClientData
 
-	// ch used to link a goroutine watching for DHCP lease file changes and the lease file processor
+	// channel used to link a goroutine watching for DHCP lease file changes and the lease file processor
 	leasesCh chan []*dnsmasq.Lease
 }
 
@@ -145,7 +145,7 @@ func NewUIBackend() UIBackend {
 			},
 		},
 		server: http.Server{
-			Addr:    bindAddress,
+			Addr:    "",
 			Handler: nil,
 		},
 	}
@@ -374,6 +374,8 @@ type AddonConfig struct {
 
 	LogDHCP  bool `json:"log_dhcp"`
 	LogWebUI bool `json:"log_web_ui"`
+
+	WebUIPort int `json:"web_ui_port"`
 }
 
 func (b *UIBackend) readAddonConfig() error {
@@ -401,6 +403,17 @@ func (b *UIBackend) readAddonConfig() error {
 	// convert DHCP IP strings to net.IP
 	b.dhcpStartIP = net.ParseIP(cfg.DhcpRange.StartIP)
 	b.dhcpEndIP = net.ParseIP(cfg.DhcpRange.EndIP)
+	if b.dhcpStartIP == nil || b.dhcpEndIP == nil {
+		log.Default().Fatalf("Invalid DHCP range found in addon config file")
+		return os.ErrInvalid // I'm lazy, recycle a similar error type
+	}
+
+	// ensure we have a valid port for web UI
+	if cfg.WebUIPort <= 0 || cfg.WebUIPort > 32768 {
+		log.Default().Fatalf("Invalid Web UI port in addon config file")
+		return os.ErrInvalid // I'm lazy, recycle a similar error type
+	}
+	b.serverPort = cfg.WebUIPort
 
 	// convert to a slice of DhcpClientFriendlyName instances
 	for _, client := range cfg.DhcpClientsFriendlyNames {
@@ -464,7 +477,8 @@ func (b *UIBackend) ListenAndServe() error {
 	go b.broadcastUpdatesToClients()
 
 	// Start server
-	log.Default().Printf("Starting server to listen on %s\n", bindAddress)
+	log.Default().Printf("Starting server to listen on port %d\n", b.serverPort)
+	b.server.Addr = fmt.Sprintf(":%d", b.serverPort)
 	b.server.Handler = mux
 	return b.server.ListenAndServe()
 }

rootfs/etc/cont-init.d/32-nginx_ingress.sh

@@ -10,10 +10,12 @@ bashio::log.info "Configuring nginx ingress..."
 declare ingress_interface
 declare ingress_port
 declare ingress_entry
+declare web_ui_port
 
 ingress_port=$(bashio::addon.ingress_port)
 ingress_interface=$(bashio::addon.ip_address)
 ingress_entry=$(bashio::addon.ingress_entry)
+web_ui_port=$(bashio::config 'web_ui_port')
 
 if [ -z "$ingress_port" ]; then
     ingress_port=8100
@@ -26,3 +28,6 @@ sed -i "s/%%port%%/${ingress_port}/g" /etc/nginx/servers/ingress.conf
 sed -i "s/%%interface%%/${ingress_interface}/g" /etc/nginx/servers/ingress.conf
 sed -i "s|%%ingress_entry%%|${ingress_entry}|g" /etc/nginx/servers/ingress.conf
 sed -i "s|%%ingress_entry%%|${ingress_entry}|g" /etc/nginx/servers/ssl.conf
+
+sed -i "s|%%web_ui_port%%|${web_ui_port}|g" /etc/nginx/servers/ingress.conf
+sed -i "s|%%web_ui_port%%|${web_ui_port}|g" /etc/nginx/servers/ssl.conf

rootfs/etc/nginx/servers/ingress.conf

@@ -11,7 +11,7 @@ server {
 
     location / {
        # Proxy
-       proxy_pass http://127.0.0.1:8080/;
+       proxy_pass http://127.0.0.1:%%web_ui_port%%/;
 
        proxy_read_timeout       30000;
        proxy_redirect           off;

rootfs/etc/nginx/servers/ssl.conf

@@ -10,7 +10,7 @@ server {
     }
 
     location %%ingress_entry%%/ {
-        set $upstream_port 8080;
+        set $upstream_port %%web_ui_port%%;
         proxy_pass http://127.0.0.1:$upstream_port;
     }
 }

translations/en.yaml

@@ -41,14 +41,17 @@ configuration:
   #     description: The last IP address of the DHCP range that defines the DHCP address pool.
   ip_address_reservations:
     name: IP Address Reservations
-    description: List of MAC addresses / IP addresses pairs that are reserved.
+    description: List of MAC addresses / IP addresses pairs that are reserved. Strict regex validation is performed on MAC addresses and hostnames (use alphanumeric chars plus dot or hyphens only).
   dhcp_clients_friendly_names:
     name: DHCP Clients Friendly Names
-    description: List of MAC addresses / friendly-name pairs to help identify the DHCP clients in the Web UI.
+    description: List of MAC addresses / friendly-name pairs to help identify the DHCP clients in the Web UI. Strict regex validation is performed on MAC addresses.
 
   log_dhcp:
     name: Log DHCP
     description: Log all details about DHCP requests served by the server
   log_web_ui:
     name: Log Web UI
     description: Log all HTTP requests served by the add-on UI
+  web_ui_port:
+    name: Web UI Port
+    description: Port used by the internal HTTP server. Change only if you get a conflict on the default port.