find ipv6 addresses

find_ipv6.go

package main

import (
	"bufio"
	"flag"
	"fmt"
	"go/scanner"
	"io"
	"io/fs"
	"os"
	"path/filepath"
	"regexp"
	"strings"
)

var (
	exitCode   = 0
	ipv6_regex = regexp.MustCompile(`(([0-9a-fA-F]{1,4}:){7,7}[0-9a-fA-F]{1,4}|([0-9a-fA-F]{1,4}:){1,7}:|([0-9a-fA-F]{1,4}:){1,6}:[0-9a-fA-F]{1,4}|([0-9a-fA-F]{1,4}:){1,5}(:[0-9a-fA-F]{1,4}){1,2}|([0-9a-fA-F]{1,4}:){1,4}(:[0-9a-fA-F]{1,4}){1,3}|([0-9a-fA-F]{1,4}:){1,3}(:[0-9a-fA-F]{1,4}){1,4}|([0-9a-fA-F]{1,4}:){1,2}(:[0-9a-fA-F]{1,4}){1,5}|[0-9a-fA-F]{1,4}:((:[0-9a-fA-F]{1,4}){1,6})|:((:[0-9a-fA-F]{1,4}){1,7}|:)|fe80:(:[0-9a-fA-F]{0,4}){0,4}%[0-9a-zA-Z]{1,}|::(ffff(:0{1,4}){0,1}:){0,1}((25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])\.){3,3}(25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])|([0-9a-fA-F]{1,4}:){1,4}:((25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])\.){3,3}(25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9]))`)
)

func usage() {
	fmt.Fprintf(os.Stderr, "usage: find-ips [path ...]\n")
	flag.PrintDefaults()
	os.Exit(2)
}

func main() {
	flag.Usage = usage
	flag.Parse()

	if flag.NArg() == 0 {
		if err := processFile("standard input", true); err != nil {
			report(err)
		}
		os.Exit(exitCode)
	}

	for i := 0; i < flag.NArg(); i++ {
		path := flag.Arg(i)
		switch dir, err := os.Stat(path); {
		case err != nil:
			report(err)
		case dir.IsDir():
			if err := walkDir(path); err != nil {
				report(err)
			}
		default:
			if err := processFile(path, false); err != nil {
				report(err)
			}
		}
	}

	os.Exit(exitCode)
}

func processFile(filename string, useStdin bool) error {
	var f *os.File
	var err error

	if useStdin {
		f = os.Stdin
	} else {
		f, err = os.Open(filename)
		if err != nil {
			return err
		}
		defer f.Close()
	}

	counter := 0
	r := bufio.NewReader(f)
	for {
		line, err := r.ReadString('\n')
		if err != nil {
			if err == io.EOF {
				break
			}
			return err
		}
		counter++
		match := ipv6_regex.FindAllString(line, -1)
		if len(match) > 0 {
			fmt.Printf("%s:%d %v\n", filename, counter, match)
		}
	}
	return nil

}

func report(err error) {
	scanner.PrintError(os.Stderr, err)
	exitCode = 2
	if err != nil {
		panic(err)
	}
}

func walkDir(path string) error {
	return filepath.WalkDir(path, visitFile)
}

func visitFile(path string, f fs.DirEntry, err error) error {
	if err == nil && isGoFile(f) {
		err = processFile(path, false)
	}
	if err != nil {
		report(err)
	}
	return nil
}

func isGoFile(f fs.DirEntry) bool {
	// ignore non-Go files
	name := f.Name()
	return !f.IsDir() && !strings.HasPrefix(name, ".") && !strings.HasSuffix(name, "test.go") && (strings.HasSuffix(name, ".md") || strings.HasSuffix(name, ".go"))
}

 go run main.go  staging/
filename:  staging/src/k8s.io/api/extensions/v1beta1/types.go
[2001:db9:: 2001:db9:: 2001:db9::]
filename:  staging/src/k8s.io/api/extensions/v1beta1/types_swagger_doc_generated.go
[2001:db9:: 2001:db9:: 2001:db9::]
filename:  staging/src/k8s.io/api/networking/v1/types.go
[2001:db9:: 2001:db9:: 2001:db9::]
filename:  staging/src/k8s.io/api/networking/v1/types_swagger_doc_generated.go
[2001:db9:: 2001:db9:: 2001:db9::]