cmd: implement chromecast scanner

cmd/scan.go

@@ -0,0 +1,84 @@
+// Copyright © 2024 Martin Holst Swende
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package cmd
+
+import (
+	"fmt"
+	"net"
+	"sync"
+	"time"
+
+	"github.com/seancfoley/ipaddress-go/ipaddr"
+	"github.com/spf13/cobra"
+)
+
+// scanCmd triggers a scan
+var scanCmd = &cobra.Command{
+	Use:   "scan",
+	Short: "Scan for chromecast devices",
+	Run: func(cmd *cobra.Command, args []string) {
+		var (
+			cidrAddr, _  = cmd.Flags().GetString("cidr")
+			port, _      = cmd.Flags().GetInt("port")
+			wg           sync.WaitGroup
+			uriCh        = make(chan string)
+			logged       = time.Unix(0, 0)
+			start        = time.Now()
+			count        int
+			ipRange, err = ipaddr.NewIPAddressString(cidrAddr).ToSequentialRange()
+		)
+		if err != nil {
+			exit("could not parse cidr address expression: %v", err)
+		}
+		// Use one goroutine to send URIs over a channel
+		go func() {
+			it := ipRange.Iterator()
+			for it.HasNext() {
+				uri := fmt.Sprintf("%s:%d", it.Next(), port)
+				if time.Since(logged) > 8*time.Second {
+					outputInfo("Scanning...  scanned %d, current %v\n", count, uri)
+					logged = time.Now()
+				}
+				uriCh <- uri
+				count++
+			}
+			close(uriCh)
+		}()
+		// Use a bunch of goroutines to do connect-attempts.
+		for i := 0; i < 64; i++ {
+			wg.Add(1)
+			go func() {
+				defer wg.Done()
+				dialer := &net.Dialer{
+					Timeout: 400 * time.Millisecond,
+				}
+				for uri := range uriCh {
+					if conn, err := dialer.Dial("tcp", uri); err == nil {
+						conn.Close()
+						outputInfo("Found (potential) chromecast at %v\n", uri)
+					}
+				}
+			}()
+		}
+		wg.Wait()
+		outputInfo("Scanned %d uris in %v\n", count, time.Since(start))
+	},
+}
+
+func init() {
+	scanCmd.Flags().String("cidr", "192.168.50.0/24", "cidr expression of subnet to scan")
+	scanCmd.Flags().Int("port", 8009, "port to scan for")
+	rootCmd.AddCommand(scanCmd)
+}

go.mod

@@ -21,6 +21,7 @@ require (
 	google.golang.org/genproto v0.0.0-20230410155749-daa745c078e1
 )
 
+require github.com/seancfoley/ipaddress-go v1.5.5
 require gopkg.in/ini.v1 v1.67.0
 
 require (
@@ -42,6 +43,7 @@ require (
 	github.com/pkg/diff v0.0.0-20210226163009-20ebb0f2a09e // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/rivo/uniseg v0.2.0 // indirect
+	github.com/seancfoley/bintree v1.2.3 // indirect
 	github.com/spf13/pflag v1.0.5 // indirect
 	github.com/stretchr/objx v0.5.0 // indirect
 	go.opencensus.io v0.24.0 // indirect

go.sum

@@ -96,6 +96,10 @@ github.com/rivo/uniseg v0.2.0/go.mod h1:J6wj4VEh+S6ZtnVlnTBMWIodfgj8LQOQFoIToxlJ
 github.com/rogpeppe/go-internal v1.8.1 h1:geMPLpDpQOgVyCg5z5GoRwLHepNdb71NXb67XFkP+Eg=
 github.com/rogpeppe/go-internal v1.8.1/go.mod h1:JeRgkft04UBgHMgCIwADu4Pn6Mtm5d4nPKWu0nJ5d+o=
 github.com/russross/blackfriday/v2 v2.1.0/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
+github.com/seancfoley/bintree v1.2.3 h1:6SPPax/9Dilcs3mDTj3CarRCWPZJV30KyP3cjcEwF70=
+github.com/seancfoley/bintree v1.2.3/go.mod h1:hIUabL8OFYyFVTQ6azeajbopogQc2l5C/hiXMcemWNU=
+github.com/seancfoley/ipaddress-go v1.5.5 h1:Q2isCacDQ3A46hxSbM9Q2+Gs4IopCVz1oH88L5eEgP4=
+github.com/seancfoley/ipaddress-go v1.5.5/go.mod h1:C+VHKCmxTfYODkkItOj9lMemZLMigwo28E+ARlPqpk0=
 github.com/sirupsen/logrus v1.8.1 h1:dJKuHgqk1NNQlqoA6BTlM1Wf9DOH3NBjQyu0h9+AZZE=
 github.com/sirupsen/logrus v1.8.1/go.mod h1:yWOB1SBYBC5VeMP7gHvWumXLIWorT60ONWic61uBYv0=
 github.com/spf13/cobra v1.4.0 h1:y+wJpx64xcgO1V+RcnwW0LEHxTKRi2ZDPSBjWnrg88Q=