pdns-auth-proxy/utils.go

package main

import (
	"encoding/json"
	"fmt"
	"math/big"
	"net"
	"sort"
	"strconv"
	"strings"

	"github.com/pyke369/golang-support/rcache"
)

func stringInSlice(a string, list []string) bool {
	for _, b := range list {
		if b == a {
			return true
		}
	}
	return false
}

// inArray checks if there is a member of "search" in "list". sort list to be more
// efficiant. adapt with sorting "search" too
func inArray(search, list []string) bool {
	sort.Strings(list)
	for _, g := range search {
		i := sort.Search(len(list), func(i int) bool { return list[i] >= g })
		if i < len(list) && list[i] == g {
			return true
		}
	}
	return false
}

// printJSON pretty print d
func printJSON(d interface{}) []byte {
	ret, _ := json.MarshalIndent(d, "  ", "  ")
	return ret
}

// reverse the part order on every member of the array
func reverse(s string) string {
	part := strings.Split(s, ".")
	for i, j := 0, len(part)-1; i < j; i, j = i+1, j-1 {
		part[i], part[j] = part[j], part[i]
	}
	return strings.Join(part, ".")
}

// domainSort sort string by first reversing them
func domainSort(s []string) {
	for i := range s {
		s[i] = reverse(s[i])
	}
	sort.Strings(s)
	for i := range s {
		s[i] = reverse(s[i])
	}
}

func ptrToIP(s string) string {
	s = reverse(s)
	count := 0
	ip := ""
	version := 4
	for _, elt := range strings.Split(s, ".") {
		switch elt {
		case "":
		case "ip6":
			version = 6
		case "in-addr":
		case "arpa":
		default:
			count++
			ip += elt
			if version == 4 && count != 4 {
				ip += "."
			}
			if version == 6 && count%4 == 0 && count != 32 {
				ip += ":"
			}
		}
	}
	return ip
}

func ipToInt(ip string) *big.Int {
	return big.NewInt(0).SetBytes([]byte(net.ParseIP(ip)))
}

// iPtoReverse calculate the reverse name associated with an IPv4 or v6
func iPtoReverse(ip net.IP) (arpa string) {
	const hexDigit = "0123456789abcdef"
	// code copied and adapted from the net library
	// ip can be 4 or 16 bytes long
	if ip.To4() != nil {
		if len(ip) == 16 {
			return uitoa(uint(ip[15])) + "." + uitoa(uint(ip[14])) + "." + uitoa(uint(ip[13])) + "." + uitoa(uint(ip[12])) + ".in-addr.arpa."
		}
		return uitoa(uint(ip[3])) + "." + uitoa(uint(ip[2])) + "." + uitoa(uint(ip[1])) + "." + uitoa(uint(ip[0])) + ".in-addr.arpa."
	}
	// Must be IPv6
	buf := make([]byte, 0, len(ip)*4+len("ip6.arpa."))

	// Add it, in reverse, to the buffer
	for i := len(ip) - 1; i >= 0; i-- {
		v := ip[i]
		buf = append(buf, hexDigit[v&0xF])
		buf = append(buf, '.')
		buf = append(buf, hexDigit[v>>4])
		buf = append(buf, '.')
	}
	// Append "ip6.arpa." and return (buf already has the final .)
	buf = append(buf, "ip6.arpa."...)
	return string(buf)
}

// Convert unsigned integer to decimal string.
// code copied from the net library
func uitoa(val uint) string {
	if val == 0 { // avoid string allocation
		return "0"
	}
	var buf [20]byte // big enough for 64bit value base 10
	i := len(buf) - 1
	for val >= 10 {
		q := val / 10
		buf[i] = byte('0' + val - q*10)
		i--
		val = q
	}
	// val < 10
	buf[i] = byte('0' + val)
	return string(buf[i:])
}

func trimPoint(s string) string {
	return strings.TrimRight(s, ".")
}

func addPoint(s string) string {
	s = trimPoint(s)
	if !strings.HasSuffix(s, ".") && !strings.HasSuffix(s, "*") {
		s = s + "."
	}
	return s
}

// add double quotes at the begining and the end of the string.
func addQuotes(s string) string {
	const q = "\""
	s = strings.Trim(s, q)
	s = strings.Replace(s, q, "\\\"", -1)
	return q + s + q
}

func validSRVName(s string) bool {
	return rcache.Get("^_[a-z0-9]+\\._(tcp|udp|tls)[^ ]+$").MatchString(s)
}

func validSRV(s string) string {
	//	_service._proto.name. TTL class SRV priority weight port target.
	match := rcache.Get("^([0-9]+) +([0-9]+) +([0-9]+) +(.+)$").FindStringSubmatch(s)
	if len(match) > 0 && validName(match[4], false) {
		return match[4]
	}
	return ""
}

func validName(s string, wildcard bool) bool {
	if !wildcard {
		return rcache.Get(
			"^(([a-z0-9]|[a-z0-9_][a-z0-9_\\-]*[a-z0-9])\\.)*([a-z0-9]|[a-z0-9][a-z0-9\\-]*[a-z0-9])\\.$").MatchString(s)
	}
	return rcache.Get(
		"^(\\*\\.)?(([a-z0-9]|[a-z0-9_][a-z0-9_\\-]*[a-z0-9])\\.)*([a-z0-9]|[a-z0-9][a-z0-9\\-]*[a-z0-9])\\.$").MatchString(s)
}

func validMX(s string) string {
	match := rcache.Get("^([0-9]+) +(.+)$").FindStringSubmatch(s)
	if len(match) > 0 && validName(match[2], false) {
		return match[2]
	}
	return ""
}

func validCAA(s string) string {
	match := rcache.Get("^([0-9]+) +(issue|issuewild|iodef) +(.+)$").FindStringSubmatch(s)
	if len(match) == 0 {
		return ""
	}
	i, _ := strconv.Atoi(match[1])
	if i < 0 || i > 255 {
		return ""
	}
	return fmt.Sprintf("%s %s %s", match[1], match[2], addQuotes(match[3]))
}